Tire Comprising a Block With a Tilted Side Wall

Abstract

Tire made of rubbery material comprising a tread (1) of width W that is delimited by at least one edge (3). The tread comprises a plurality of blocks (5), each block being delimited by at least one lateral wall (7) that extends mainly in an axial direction Y in the direction of the edge (3). The lateral wall (7) has a length L in this axial direction Y, where L is greater than 35% of the width W of the tread. The lateral wall also exhibits an inclination angle (a) with respect to a radial direction (Z), said inclination angle (a) evolving in the axial direction Y, this evolution being continuous.

Claims

1. A tire made of rubbery material, comprising a tread of width W that is delimited by at least one edge, the tread comprising a plurality of blocks, each said block being delimited by at least one lateral wall that extends mainly in an axial direction Y in the direction of the edge, the lateral wall having a length L in this axial direction, where L is greater than 35% of the width W of the tread, wherein the lateral wall exhibits an inclination angle () with respect to a radial direction, said inclination angle (a) evolving in the axial direction Y, said evolution being continuous.

2. The tire according to claim 1, wherein the evolution in the inclination angle (a) is in accordance with a Gaussian function.

3. The tire according to claim 1, wherein the evolution in the inclination angle (a) is in accordance with a polynomial function.

4. The tire according to claim 1, wherein the evolution in the inclination angle (a) is in accordance with an exponential function.

5. The tire according to claim 1, wherein, the tread having a centre, the block extends from the centre of said tread to the edge along a curve C.

6. The tire according to claim 1, wherein, each said block is divided into a plurality of block segments.

7. The tire according to claim 1, wherein, the lateral wall delimits a groove that extends towards the edge of the tread, the groove having a cross section, the cross section of said groove increases in the direction of this said edge.

8. The tire according to claim 1, wherein the values of the inclination angle (a) are between 10 and 30.

9. The tire according to claim 1, wherein, the inclination angle (a) being able to have a maximum value and a minimum value, the difference between this maximum value and this minimum value is at least 10.

10. The tire according to claim 9, wherein the maximum value of the inclination angle is 15 and its minimum value is 5.

11. The tire according to claim 1, wherein the block is delimited by another lateral wall, said other lateral wall exhibiting an inclination angle () that evolves continuously.

12. The tire according to claim 11, wherein, the tread being directional, the block has a leading edge belonging to the lateral wall of said block and the block has a trailing edge belonging to the other lateral wall of the block, the maximum value of the inclination angle (a) of the lateral wall that forms the trailing edge being greater than the maximum value of the inclination angle () of the lateral wall that forms the leading edge.

13. The tire according to claim 1, wherein the block is divided into a plurality of sub-blocks separated by secondary grooves that extend mainly in a circumferential direction.

14. The tire according to claim 1, the block has a chamfered part at its lateral wall.

15. The tire according to claim 1, wherein the lateral wall of the block has one or more discontinuities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Further 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:

[0043] FIG. 1 schematically shows a partial view of a tread of a tire according to the invention;

[0044] FIG. 2 shows a view in cross section on A-A of a block of the tread in FIG. 1;

[0045] FIG. 3 shows a schematic view of the evolution of an inclination angle of a lateral wall of the block in FIG. 2;

[0046] FIG. 4 shows a partial view of a tread of a tire according to a second embodiment of the invention;

[0047] FIG. 5 shows a partial view of a tread of a tire according to a third embodiment of the invention;

[0048] FIG. 6 shows a variant embodiment according to a fourth embodiment of the invention;

[0049] FIG. 7 shows a variant embodiment according to a fifth embodiment of the invention;

[0050] FIG. 8 shows a variant embodiment according to a sixth embodiment of the invention.

[0051] In the following description, elements which are substantially identical or similar will be denoted by identical references.

[0052] FIG. 1 schematically presents a partial view of a tread 1 of a tire according to the invention. The tread 1 is delimited by two edges 3 and a centre 9 separating the tread into two treads. This tread 1 has a width W measured between these two edges 3. This width W is determined to be equal to +/10% of a nominal width Wnom. This nominal width Wnom is determined with the aid of the following formula: Wnom=(1.0750.005*ar)*S.sup.1.001 where ar is the nominal aspect ratio expressed in base 100 and S is the theoretical section width on the measuring rim expressed in mm Thus, for a tire of size 205/55 16, Wnom is equal to (1.0750.005*55)*(205).sup.1.001=165 mm.

[0053] The tread 1 also comprises a plurality of raised rubber blocks 5. These rubber blocks 5 are organized in the tread so as to form a particular tread pattern design. In the embodiment in FIG. 1, the rubber blocks 5 extend from the centre 9 of the tread 1 to respective edges 3, specifically along a curve C. The tread pattern formed is referred to as directional in this case. Thus, each rubber block 5 has a leading edge 13 and a trailing edge 15. The leading edge 13 is that part of the block 5 that will come into contact with a road surface first during acceleration of the vehicle. The trailing edge 15 is that part of the block 5 that will come into contact first during braking. In a variant, the organization of the rubber blocks 5 could be different; for example, the tread pattern formed by these blocks 5 could be non-directional.

[0054] Each block is delimited by at least one lateral wall 7. This lateral wall 7 delimits a groove 8 which extends mainly in an axial direction Y in the direction of the edge region 3. It will be noted that the lateral wall 7 has a length L in this axial direction Y, where L is greater than 35% of the width W of the tread. It will also be noted that, in a preferred embodiment, the cross section of the groove 8 increases in the direction of the edge 3. In the example in FIG. 1, where the tread pattern is directional, the lateral wall 11 delimits the leading edge 13 and the lateral wall 7 on the opposite side from the lateral wall 11 in the block 5 delimits the trailing edge.

[0055] FIG. 2 presents a view in cross section on A-A of a block 5 of the tread 1. More particularly, the lateral wall 11 of the block 5 forms an inclination angle with respect to a radial direction Z. This inclination angle evolves in the axial direction Y in FIG. 1, this evolution being continuous in this axial direction. The lateral wall 7, on the opposite side from the lateral wall 11, for its part forms an inclination angle with respect to the radial direction Z. The evolution in the inclination angle may, for its part, also be continuous in the axial direction Y. The inclination angles and have values of between 10 and 30. It will be noted that when the value of the angle is negative, the width of the groove associated with the lateral wall increases with depth into this groove. Conversely, when the value of the angle is positive, the width of the associated groove decreases with depth into the groove.

[0056] In a preferred embodiment, the evolutions of the inclination angles , are in accordance with a Gaussian curve 10, as is shown in FIG. 3. In this FIG. 3, it can be seen that the values of the inclination angles and are at a maximum at L/2, i.e. half-way across the half-tread.

[0057] FIG. 4 presents an alternative embodiment in which the block 5 is divided into a plurality of sub-blocks 17a, 17b, 17c separated by secondary grooves 19. These secondary grooves extend mainly in a circumferential direction X. In this example, the grooves 19 do not extend all the way into the depth of the tread, such that the walls 7 and 11 extend continuously from the centre of the tread to the edge.

[0058] In a variant embodiment shown in FIG. 5, the grooves 19 extend all the way into the depth of the tread, such that the sub-blocks 17a, 17b, 17c are clearly separated. Thus, the walls 7 and 11 do not in this case extend continuously from the centre of the tread to the edge, since the grooves 19 create discontinuities. However, the evolution of the inclination angles of these walls 7, 11 is continuous, since these angles remain a function of a distance measured from the centre of the tread.

[0059] In an alternative embodiment, the block 5 has a chamfered part 23 at its lateral wall, as can be seen in FIG. 6.

[0060] In another embodiment, which can be seen in FIG. 7, the lateral wall 7 of the block 5 has one or more discontinuities 25. In the same way here, the evolution of the inclination angle of the wall 7 is continuous, since this angle remains a function of a distance measured from the centre of the tread.

[0061] In another embodiment, which can be seen in FIG. 8, each block 5 is divided into a plurality of block segments 27, 29, 30. More particularly, the block 5 comprises a central segment 27 that extends generally at an angle 1, such that 35165 to a transverse direction Y. The block 5 also comprises an edge segment 30 that extends generally at an angle 2 such that 0210 to the transverse direction Y. The block 5 finally comprises a joining segment 29 between the central segment 27 and the edge segment 30.

[0062] The invention is not limited to the examples described and shown and various modifications can be made thereto without departing from its scope.