Tread Layer For A Tire Comprising Channels

Abstract

A tire comprising a tread. This tread comprises at least one elongate block delimited by at least one lateral wall (5) and a contact face (7). The lateral wall (5) makes a non-zero angle with a transverse direction and the contact face contacts a road surface. The tire comprises at least one channel (19) extending through the elongate block and leading onto the lateral wall (5) of this elongate block. The tire also comprises a sipe extending from the channel towards the contact face, this sipe leading onto the lateral wall of the elongate block in a lateral wall outlet region. The lateral wall of the elongate block is inclined with respect to a radial direction (Z), at least in the lateral wall outlet region of the sipe, at an angle of between 20 degrees and 60 degrees with respect to this radial direction (Z).

Claims

1. A tire comprising a tread, said tread comprising at least one elongate block, the elongate block being delimited by at least one lateral wall and a contact face, said lateral wall making a non-zero angle with a transverse direction, said contact face being adapted to come into contact with a road surface, the tire comprising at least one channel that extends through the elongate block and leads onto the lateral wall of this elongate block, the tire comprising a sipe towards the contact face, said sipe leading onto the lateral wall of the elongate block in a lateral wall outlet region, wherein the lateral wall of the elongate block is inclined with respect to a radial direction, at least in the lateral wall outlet region of the sipe, at an angle of between 20 degrees and 60 degrees with respect to said radial direction.

2. The tire according to claim 1, the tread comprising a centre and an edge, wherein the elongate block is part of a set of blocks, said set of blocks extending from the edge of the tread towards the centre, generally along a curvature C, said set of blocks being repeated around the entire circumference of the tire such that the tire is directional, at least in part, and wherein the elongate block is separated from another block of the set of blocks by a groove, said groove delimiting the inclined lateral wall of the elongate block into which the sipe and the channel lead.

3. The tire according to claim 1, wherein, with the sipe leading onto the contact face in a contact face outlet region of the sipe, said contact face outlet region of the sipe comprises a texture that contrasts with the rest of the contact face, said texture being produced integrally with the elongate block.

4. The tire according to claim 3, wherein the texture comprises a plurality of strands distributed through the texture at a density at least equal to one strand per square millimetre (mm.sup.2), each strand having a mean cross section of between 0.003 mm.sup.2 and 1 mm.sup.2.

5. The tire according to claim 3, wherein the texture comprises a plurality of lamellae having a spacing of less than 0.3 mm and a mean width of between 0.03 mm and 0.25 mm.

6. The tire according to claim 5, wherein, with the sipe forming a line on the contact face of the elongate block, the lamellae of the texture extend generally parallel to said line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features and advantages of the invention will become apparent from the following description, given by way of non-limiting example, with reference to the attached drawings in which:

[0029] FIG. 1 shows a partial view of a tread of a tire according to the invention;

[0030] FIG. 2 schematically shows a view in cross section of an elongate block of the tread from FIG. 1;

[0031] FIG. 3 is an enlarged view of an elongate block of the tread from FIG. 1;

[0032] FIG. 4 shows an enlarged view of an elongate block of the tread from FIG. 1, comprising a texture;

[0033] FIG. 5 describes a texture present on the elongate block from FIG. 3, according to a first embodiment;

[0034] FIG. 6 describes a texture present on the elongate block from FIG. 3, according to a second embodiment.

[0035] In the following description, elements which are substantially identical or similar will be denoted by identical references.

[0036] FIG. 1 shows a partial view of a tread of a tire. This tread comprises at least one elongate block 3 extending in a main direction U. This main direction U makes a non-zero angle with a transverse direction Y. In a preferred embodiment, the main direction of the elongate block is between 45 degrees and 80 degrees with respect to the transverse direction Y. The elongate block 3 comprises a sipe 11 that leads onto a contact face 7 of the elongate block, forming a line which is rectilinear in this case. The elongate block 3 also comprises a channel 9 disposed at a depth in the block, the sipe 11 connecting the channel 9 to the contact face 7 of the block. The channel 9 and the sipe 11 lead onto a lateral wall 5 of the elongate block 3.

[0037] As can be seen in FIG. 2, the lateral wall 5 of the elongate block 3 is inclined with respect to a radial direction Z by an angle of between 20 degrees and 60 degrees with respect to this radial direction Z. In other words, with the angle , the groove 19 bordering the lateral wall 5 widens from the bottom of the groove 19 towards the surface of the tread. The inclination of the lateral wall 5 makes it easier to evacuate stones that act on this lateral wall, notably during a transverse movement of these stones with respect to the elongate block 3. In this way, the stresses generated by the stones on this lateral wall 5 are limited, notably in the rubber part present above the outlet of the channel 9 on the lateral wall 5 close to the sipe 11 (hatched part 12 in FIG. 3).

[0038] It will be noted that, in FIGS. 1 to 3, it is the entire lateral wall 5 of the elongate block 3 that is shown as being inclined. Alternatively, only a region of the lateral wall 5 is inclined, this region being centred on the sipe 11 and the width of this region being at least twice the width of the sipe 11.

[0039] It will also be noted that the channel 9 and the sipe 11 lead onto a lateral wall which extends generally in a manner perpendicular to the main direction of extension U of the elongate block 3. Alternatively, the channel and the sipe can lead onto a lateral wall parallel to this main direction of extension U.

[0040] Finally, it will be noted that, in FIG. 1, the elongate block 3 is part of a set of blocks 17 comprising in this case three blocks. The set of blocks 17 extends from one edge 15 of the tread towards a centre 13 of this tread, generally along a curvature C. The blocks of the set of blocks 17 widen from the centre 13 towards the edge 15. The set of blocks is in this case repeated on each side of the centre 13 of the tread and around the entire circumference of the tire, such that the tread is directional. A directional tread means a tread that has a preferred rolling sense such that, when the tire is rotated in this preferred sense, the latter affords properties of grip on the ground that are better than those afforded when the tire is rotated in the other sense.

[0041] In FIG. 1, the elongate block 3 is separated from another block 4 of the set of blocks 17 by the groove 19. As has already been specified, the groove 19 delimits the inclined lateral wall 5 of the elongate block 3 into which the sipe 11 and the channel 9 lead.

[0042] FIG. 4 shows an enlarged view of the elongate block 3 of the tread. This block 3 comprises a contact face 7 onto which the sipe 11 leads. The block 3 also comprises a texture 21 produced integrally with the contact face 7 and contrasting with the rest of the contact face 7. This texture surrounds the outlet of the sipe 11 on the contact face 7 in a region that is centred on the sipe and has a width at least twice the width of the sipe. A texture means an organized arrangement of a plurality of elements, all or some of the elements in the arrangement being the repetition of one and the same basic element, for example a strand or a lamella.

[0043] A strand means a filiform element, the height of which is at least equal to twice the diameter of a disc having the same surface area as the mean cross section of the strand. The texture involving strands 23 is illustrated in FIG. 5.

[0044] Lamellae means elongate strands which have a length at least equal to twice their height. The texture involving lamellae 25 is illustrated in FIG. 6.

[0045] The effect of these strands or lamellae is to trap a large quantity of the incident light rays that strike the texture 21, such that this texture 21 appears to be blacker than the rest of the contact face 7.

[0046] In FIG. 5, the strands 23 are distributed in the texture 21 at a density at least equal to one strand per square millimetre (mm.sup.2), each strand having a mean cross section S of between 0.003 mm.sup.2 and 1 mm.sup.2. It will be noted that the mean cross section of each strand corresponds to the mean of the cross sections S measured at regular intervals from the base of the strand. The strands 6 have a conical overall shape with a cross section that decreases over the height Hb of these strands.

[0047] In FIG. 6, the lamellae 25 are substantially parallel to one another. The spacing P of the lamellae in the texture is between 0.1 mm and 0.5 mm Each lamella has a mean width of between 0.03 mm and 0.25 mm. The mean width corresponds in this case to the mean of the widths 1 measured at regular intervals over the height Hl of the lamella, the height of each lamella being between 0.05 mm and 0.5 mm. In a preferred embodiment, the lamellae 25 of the texture 21 extend parallel to the line formed by the sipe 11 on the contact face of the elongate block.

[0048] The invention is not limited to the examples described and shown and various modifications can be made thereto without departing from its scope.

[0049] Thus, it is possible for the lines formed by the sipe 11 on the contact face 7 of the block or on the inclined lateral wall 5 not to be rectilinear. These lines may, for example, be curved, zigzag-shaped or the like.

[0050] Moreover, it is possible for the sipe 11 and the channel 9 not to be aligned but to form a non-zero angle between their respective directions of extension.