Pneumatic Tire

Abstract

Pneumatic tire comprising a tread (1) provided with two edges (2), a center (3) and a plurality of tread bars (10) distributed in a circumferential direction, each tread bar (10) extending in an oblique direction from one of the edges (2) towards the center (3) of said tread (1), the plurality of tread bars (10) comprising at least two adjacent tread bars (11, 12); each of said adjacent tread bars (11, 12) has at least one incision (20, 21, 23) extending along the length of the tread bar, each adjacent tread bar has an overall incision length (LGI) corresponding to the sum of the lengths of the incisions that are part of said tread bar, the widths (LB11, LB12) of said adjacent tread bars (11, 12) are different, and the overall incision length (LGI) in said adjacent tread bars (11, 12) is different.

Claims

1. A fire having a tread, a centre and a plurality of blocks distributed in a circumferential direction, each block extending from one of the edges towards the centre of said tread in an oblique direction, the plurality of blocks comprising at least two adjacent blocks, each adjacent block of said adjacent blocks having at least one sipe extending along the length of the block, each adjacent block having an overall sipes length LGI corresponding to the sum of the lengths of the sipes belonging to said block, wherein the widths of said adjacent blocks are different and the overall sipes length LGI in said adjacent blocks is different.

2. The tire according to claim 1, wherein the sipes divide each block into two half-blocks, the separation being substantially in the longitudinal direction of the blocks.

3. The tire according to claim 1, wherein for each of said adjacent blocks, the number of sipes Nib and the width of the block are chosen such that: 3.5 mm<LB/(Nib+1)<7 mm.

4. The tire according to claim 1, wherein at least one block of said adjacent blocks comprises a first sipe and a second sipe, each sipe extending along the length of said block, and in that the first sipe has a depth H.sub.GE, said first sipe having a widened portion in said depth, and in that said second sipe has a depth H.sub.L, where 0.1 H.sub.GE<H.sub.L<0.9 H.sub.GE.

5. The tire according to claim 4, wherein said second sipe has a depth H.sub.L, where 0.4 H.sub.GE<H.sub.L<0.6 H.sub.GE.

6. The tire according to claim 4, wherein the depth H.sub.GE of the first sipe is between 6 mm and 8 mm.

7. The tire according to claim 4, wherein the first sipe divides the block into two half-blocks.

8. The tire according to claim 1, wherein at least one of said adjacent blocks extends substantially as far as one of the edges of said tread.

9. The tire according to claim 8, wherein said adjacent blocks extending as far as one of the edges of the tread comprise a groove separating at least one block into two axially spaced-apart parts.

10. The tire according to claim 9, wherein each part of said adjacent block comprises a different number of sipes.

11. The tire according to claim 1, wherein the tread is directional.

Description

DESCRIPTION OF THE FIGURES

[0026] All the embodiment details are given in the following description, supplemented by FIGS. 1 to 6, which are given only by way of non-limiting examples and in which:

[0027] FIG. 1 is a schematic cross-sectional depiction of an example of a tread pattern block;

[0028] FIG. 2 is a schematic depiction of a portion of a tread corresponding substantially to the contact patch for a first exemplary embodiment;

[0029] FIG. 3 is a schematic depiction of a portion of a tread corresponding substantially to the contact patch for a second exemplary embodiment;

[0030] FIG. 4 is a schematic depiction of a portion of a tread corresponding substantially to the contact patch for an embodiment variant of the example in FIG. 3;

[0031] FIG. 5 is a schematic depiction of a portion of a tread corresponding substantially to the contact patch for another embodiment variant of the example in FIG. 3;

[0032] FIG. 6 is a schematic depiction of a tread block comprising a plurality of sipes, the lengths of each of the sipes being depicted.

DETAILED DESCRIPTION OF THE INVENTION

[0033] FIG. 2 is a schematic depiction of a first implementation example illustrating a portion of a tread 1 of a tire. This tread has two edges 2, a central axis 3 and a plurality of blocks 10 distributed circumferentially over the tread. The blocks 10 are advantageously arranged with a certain inclination with respect to the axis 3, for example between 30° and 60°, and more preferably 45°. In the following text, this inclination is referred to as the oblique direction of the blocks.

[0034] In this embodiment, the blocks 10 start with a slight offset with respect to the edge 2 of the tread. They then continue towards the central axis 3. The plurality of blocks 10 comprises at least two adjacent blocks 11 and 12. The block 11 has a block width LB11 and the block 12 has a block width LB12. These blocks are each provided with at least one sipe 20, 21, 23 extending along the length of the block.

[0035] As can be seen in the example in FIG. 2, but also in the examples in FIGS. 3 to 5, the widths LB11 and LB12 of the two adjacent blocks 11 and 12 are different. In the examples illustrated, the width LB11 is greater than the width LB12.

[0036] These figures also make it possible to observe that the number of sipes Nib in these two adjacent blocks 11 and 12 is different. For each of the two adjacent blocks 11 and 12, the number of sipes Nib and the widths LB11 and LB12 of the blocks are chosen in accordance with the following dimensional relationship: 3.5 mm<LB/(Nib+1)<7 mm.

[0037] In the example in FIG. 2, there are three sipes extending along the blocks 11, dividing these blocks into four elongate and parallel parts. As can be seen in FIG. 1, which shows a cross section through an example of a block 10 comprising three sipes 20, the central sipe, referred to as the first sipe 21, has a depth H.sub.GE and has a widened portion 22 in the deepest portion. The first sipe 21 divides the block into two half-blocks.

[0038] The lateral sipes, referred to as second sipes 23, have a depth H.sub.L. The depths H.sub.L and H.sub.GE are advantageously provided depending on the following relationship: 0.1 H.sub.GE<H.sub.L<0.9 H.sub.GE. In a variant, the relationship is more restrictive, as follows: 0.4 H.sub.GE<H.sub.L<0.6 H.sub.GE.

[0039] The depth H.sub.GE of the first sipe 21 is between 6 mm and 8 mm.

[0040] FIG. 3 is a schematic depiction of a second embodiment of the tire, in which at least one of said two adjacent blocks 11 and 12 extends substantially as far as one of the edges 2 of said tread 1. In the example illustrated, all of the blocks 10 extend as far as one of the edges 2. The axially outer portion of the blocks is slightly curved, such that the axially outer end of the blocks is substantially perpendicular to the circumferential axis 3.

[0041] FIG. 4 is a schematic depiction of a third embodiment of the tire, constituting a variant of the embodiment in FIG. 3, in which a groove 5 separates the blocks into two axially spaced-apart parts. In this exemplary embodiment, the number of sipes is identical in both parts of the blocks. The widest blocks 11, of width LB11, comprise three sipes, with an arrangement as illustrated in the block in FIG. 1. The narrower blocks 12, of width LB12, have a single sipe, with or without a widened portion 22.

[0042] FIG. 5 illustrates another embodiment variant, in which each part of the adjacent blocks comprises a different number of sipes 20, 21, 23. The sipes may or may not have a widened portion 22. In this example, the widest central blocks comprise three sipes and the widest lateral blocks 11 comprise two sipes. The narrower central blocks have a single sipe, and the narrower lateral blocks 12 have two sipes.

[0043] The overall sipes length LGI of a block corresponds to the sum of the lengths each of the sipes of this block, taking the projection of the added length onto a transverse axis (perpendicular to the axis 3 of the tire) into account. FIG. 6 is a schematic depiction of a tread block 11 having a central sipe 21 and two lateral sipes 23. The lengths of each of the sipes are represented as follows: Li a for the length of the bottom sipe 23 in the figure, Li b for the length of the central sipe 21 of the block and Li c for the length of the top sipe 23 in the figure. The overall sipes length LGI of the block 11 in FIG. 6 is therefore the sum of the lengths Li a+Li b+Li c.

[0044] For a block 12 having a single sipe 20, the overall sipes length LGI of the block corresponds to the length of this single sipe, taking the projection of the added length onto a transverse axis (perpendicular to the axis 3 of the tire) into account. FIG. 2 illustrates an example of length LGI of a block 12.

[0045] In the different examples illustrated, the tread 1 is advantageously directional.

REFERENCE NUMERALS EMPLOYED IN THE FIGURES

[0046]

TABLE-US-00001 1 Tread 2 Tread edge 3 Tread central axis 4 Oblique groove 10 Blocks 11, 12 Adjacent blocks 20 Sipes 21 Sipe with widened portion 22 Widened portion 23 Sipe without widened portion