EP3292005A1

EP3292005A1 - Tread including a block having a plurality of cut-outs

Info

Publication number: EP3292005A1
Application number: EP16723442.6A
Authority: EP
Inventors: Benoit DURAND-GASSELIN; Kenji Fukuda; Kazunori INABA
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2015-05-07
Filing date: 2016-05-04
Publication date: 2018-03-14
Also published as: US20180134089A1; WO2016177977A1; CN107531100A; FR3035823A1; BR112017023887A2; JP2018514453A

Abstract

The invention relates to a tyre made of rubber material comprising a tread (1), said tread having a width C measured between two edges (3) of the tread, the tread comprising a tread surface (5) intended for engaging with the ground. The tread surface (5) comprises two shoulder areas (7a, 7b) surrounding a central area (9), at least one of the two shoulder areas (7a, 7b) includes a plurality of cut-outs (11a, 11b) in sequence in a circumferential direction (X). All or part of the cut-outs (11a, 11b) of the plurality of cut-outs extend in an oblique manner, each cut-out having two ends (13a, 13b) and when one cut-out (11a) reaches one of the ends (13b) thereof, another cut-out (11b) starts at the same circumferential level (N) in the shoulder area (7a).

Description

ROLLING STRIP COMPRISING A BLOCK PRESENTING A PLURALITY OF CUTTINGS

FIELD OF THE INVENTION

[01] The present invention relates to a tread of a tire for a motor vehicle provided with means for substantially reducing the rolling noise.

STATE OF THE ART

[02] In the usual way, tires for passenger vehicles are provided with a carcass reinforcement which today is radial for the most part; in this configuration, the reinforcements of the carcass reinforcement are arranged to make an angle greater than or equal to 80 degrees and less than 100 degrees with a circumferential direction.

[03] In addition, the tires are provided with a crown reinforcement comprising a plurality of reinforcements embedded in a material based on elastomers. This crown reinforcement is covered radially on the outside by a tread made of rubber material, this strip having a surface, called a tread surface, intended to be in contact with the road while driving.

[04] In order to ensure an essential level of safety in particular in rainy weather, it is known to provide the tread with a plurality of longitudinal grooves of generally circumferential orientation.

[05] A disadvantage of the presence of longitudinal grooves is the generation of vibrations of the air flowing in these grooves, especially in the area of contact with the road. These vibrations are the source of resonances generating a rolling noise.

[06] EP0324605 discloses a tread having a plurality of blocks aligned in a circumferential direction. In this document, the blocks are inclined at a certain angle on the running surface in order to reduce the generation of noise while taxiing.

[07] There is known a tread comprising a tread surface, the tread surface having two shoulders areas surrounding a central area. The shoulder areas comprise a plurality of transverse incisions succeeding one another in a circumferential direction. These transverse incisions are intended in particular to improve the adhesion on wet ground. However, the inventors have observed that these transverse incisions generate noises of significant intensity when they penetrate into the area of contact with the ground during travel.

[08] There is a need to limit the generation of tread noise, including noises generated at shoulder areas of this tread.

DEFINITIONS [09] "Pneumatic" means all types of elastic bandages subjected to internal pressure or not.

[10] "Tread" of a tire means a quantity of rubber material delimited by side surfaces and by two major surfaces, one of which is intended to come into contact with a roadway when the tire is rolling.

[11] "Tread surface" means all the points of the tread which are in contact with the roadway when the tire, inflated to its reference pressure, is rolling on that roadway. The reference inflation pressure is defined in the conditions of use of the tire as defined in particular by the standard E.T.R.T.O. ("European Tire and Rim Technical Organization").

[12] By "block" on a tread means a relief element delimited by grooves and comprising side walls and a contact face, the latter being intended to come into contact with the ground during a period of time. rolling. [13] "Extended block" means a block having a width and a length on the circumference of the tire, this length being much greater than the width.

[14] "Rib" means an elongated block which extends over the entire circumference of the tire.

[15] By "groove" is meant a cut in the tread delimiting material walls, the width of this cutout is such that the walls associated with this cutout can not come into contact one against the other under normal driving conditions. The width for a groove is greater than 2 millimeters.

[16] "Incision" means a cut in the tread delimiting material walls, the width of this cutout is appropriate to allow the contact, at least partially, the walls of the incision during the passage in the contact area between the tire and the ground. The width for an incision is less than or equal to 2 millimeters.

[17] The term "transverse direction" or "axial direction" means a direction parallel to the axis of rotation of the tire.

[18] "Circumferential direction" means a direction that is tangent to any circle centered on the axis of rotation. This direction is perpendicular to the axial direction.

[19] By "oblique direction" is meant a direction which has an axial component and a non-zero circumferential component.

[20] By "circumferential level" is meant a set of points forming a line, this line being perpendicular to the circumferential direction. [21] By "circumferential level" is meant a set of points forming a straight line, this straight line being perpendicular to the circumferential direction.

[22] "Midplane" means a plane perpendicular to the axis of rotation of the tire and passing through the middle of the tread. SUMMARY OF THE INVENTION

[23] The invention relates to a rubber tire comprising a tread. The tread has a width W measured between two edges of the tread, the tread comprising a tread surface intended to come into contact with a ground, the tread surface comprising two shoulder zones surrounding a central zone. At least one of the two shoulder zones comprises a plurality of cutouts succeeding one another in a circumferential direction. All or part of the cutouts of the plurality of cuts extends obliquely, each cutout having two ends, and in that when a cut reaches one of its ends, another cutout starts at the same circumferential level in the shoulder zone. .

[24] The invention thus proposes to ensure continuity in the organization of the cutouts in the shoulder zone. Indeed, when a cut reaches one of its ends, another cut starts at the same circumferential level. In this way, the variation of the notching rate of the shoulder zone is limited in the circumferential direction and the acoustic performance of the tire is then improved.

[25] In an alternative embodiment, the oblique cutouts are at an angle with a transverse direction. The angle a is between 5 degrees and 60 degrees. Preferably, the angle is between 15 degrees and 45 degrees.

[26] The adhesion performance of the tire on wet surfaces is improved, particularly in turns, when the shoulder areas of the tread are the most stressed.

[27] In another alternative embodiment, the oblique cutouts are extended by generally transverse cutout extensions. These extensions cutting edges extend from the oblique cut-outs to an edge of the tread, and in that the length of the cut-out extensions is less than 10% of the width W of the tread.

[28] The transverse cutout extensions limit the noise generated when taking turns, ie when there is a load transfer from the center of the tread to one of the shoulder areas.

[29] In another alternative embodiment, the oblique cutouts open into a circumferential groove belonging to the central area of the running surface.

[30] It thus facilitates the flattening of the tread on the ground and generally improves the adhesion of the tire on wet ground.

[31] In another embodiment, each shoulder zone comprises a series of oblique cuts and in that the cutouts of the two shoulder areas are symmetrical with respect to a median plane.

[32] The cutouts are then particularly suitable for use in directional sculptures.

[33] In another embodiment, each shoulder zone comprises a series of oblique cuts and in that the cutouts of the two shoulder areas are unsymmetrical with respect to a median plane.

[34] The cutouts are then particularly suitable for use in non-directional sculptures.

[35] In another alternative embodiment, the two series of oblique cuts are offset from one another in the circumferential direction. [36] Noise coupling between the two series of cutouts is avoided. This prevents the cutouts of the two series of cuts simultaneously in contact with the ground and thus improves the overall acoustic performance of the tire.

[37] In an alternative embodiment, the cutouts are incisions.

[38] This improves the adhesion of the tread on a wet road while maintaining a certain overall stiffness of the shoulder areas.

[39] In an alternative embodiment, the cutouts are grooves.

[40] This improves the flow of water out of the tread when the tire is rolling on wet ground.

[41] In an alternative embodiment, the central region of the tread comprises at least one elongate block in the circumferential direction. The elongate block has a contact surface for contacting a floor and a first side wall and a second side wall defining the contact surface. The elongate block has a plurality of cutouts opening on the contact surface of the block. Each cutout extends in an oblique direction, opening onto the first side wall and the second side wall. The cutouts of the block are oriented in the same direction and the cutouts are distributed over the contact surface of the elongated block so that when a cutout reaches the second side wall another cut starts from the first side wall, at the same level. circumferential on the elongated block.

[42] This ensures a continuity in the organization of the cuts in the elongated block and limits the noise generated by this elongated block. [43] In another alternative embodiment, the central zone comprises at least one elongate block in the circumferential direction (X) of width W and length L with L »W, the elongate block comprising a contact surface intended to come into contact with a floor and a first side wall and a second side wall defining the contact surface. The elongate block has a plurality of oblique cutouts opening alternately on the first side wall or on the second side wall and extending to ends of cuts that do not open on said side walls. The cutouts of the plurality of cutouts are distributed over the contact surface of the block so that when a cutout reaches its cutout end another cutout starts from a sidewall at the same circumferential level on the elongated block.

[44] In another alternative embodiment, the central zone comprises at least one elongated block in the circumferential direction of width W and length L with L »W, the elongated block comprising a contact surface intended to come into contact with a floor and a first side wall and a second side wall defining the contact surface. The elongated block has a plurality of cutouts opening on the contact surface of the elongate block. The cutouts extend obliquely from the first sidewall toward the second sidewall to cutout ends. For at least one cutout, its end does not open on the second sidewall and when this cutout reaches its cutout end another cutout starts from the first sidewall at the same circumferential level on the elongated block.

BRIEF DESCRIPTION OF THE DRAWINGS

[45] Other features and advantages of the invention will emerge from the following description, given by way of example, without limitation, with reference to the accompanying drawings, in which: FIG. 1 schematically represents a partial view of a tread comprising incisions, according to a first embodiment of the invention; Figure 2 schematically shows a second embodiment of the invention with incisions; Figure 3 schematically shows a third embodiment of the invention with incisions; Figure 4 schematically shows a fourth embodiment of the invention with incisions; Figure 5 shows schematically a fifth embodiment of the invention with incisions; Figure 6 shows schematically a sixth embodiment of the invention with incisions; Figure 7 shows schematically a seventh embodiment of the invention with incisions; Figure 8 shows schematically an eighth embodiment of the invention with incisions; Figure 9 shows schematically a ninth embodiment of the invention with incisions; Figure 10 shows schematically a partial view of a tread having grooves, according to a tenth embodiment of the invention; Figure 11 shows schematically an eleventh embodiment of the invention with grooves; Figure 12 shows schematically a twelfth embodiment of the invention with grooves; Figure 13 shows schematically a thirteenth embodiment of the invention with grooves; Figure 14 shows schematically a fourteenth embodiment of the invention with grooves; Figure 15 shows schematically a fifteenth embodiment of the invention with grooves; Figure 16 shows schematically a sixteenth embodiment of the invention with grooves; Figure 17 shows schematically a seventeenth embodiment of the invention with grooves; Figure 18 shows schematically an eighteenth embodiment of the invention with grooves.

[46] In the following description, substantially identical or similar elements will be designated by identical references.

[47] Figure 1 and Figure 10 respectively show a partial view of a tread 1 of a tire according to a first embodiment of the invention.

[48] The tread 1 comprises a tread surface 5 intended to come into contact with a ground. This running surface has a width C, width measured between two edges 3 of the tread. This width C of the surface of the tread is defined in particular by the ETRTO standard such that C = (1.075-0.005 ar) * S ^{1 001} with ar the nominal aspect ratio and s the size of the theoretical strand on a rim measurement.

[49] More particularly, the running surface comprises two shoulder zones 7a, 7b surrounding a central zone 9. By shoulder zones, it is meant the areas of the running surface which are located near the edges 3 of this tread. The shoulder areas 7a, 7b are here constituted by two elongated blocks in a circumferential direction X. At least one of the shoulder areas comprises a plurality of cutouts 11a, 11b. In the case of Figure 1 and Figure 10, the cutouts 11a, 11b are incisions. In the case of Figure 10, the cutouts 11a, 11b are grooves. These cuts follow one another in the circumferential direction X. Each cut-out extends between two ends 13a, 13a at an angle α, which is not zero, with a transverse direction Y. The angle a is here between 5 degrees and 60 degrees. degrees and preferably between 15 degrees and 45 degrees. The cutouts 11a, 1b are remarkable in that when the cutout 11a reaches one of its ends 13b, another cutout 11b starts at the same circumferential level N in the shoulder zone 7a. In the case where the cuts are grooves, the notion of neutral fiber is used for determining the same circumferential level between two adjacent grooves. The neutral fiber of a groove divides this groove into two grooves having substantially the same volume.

[50] The cut-outs 11a, 11b here have a simple rectilinear shape. In a variant, these cutouts 11a, 11b may form curved traces on the surface of the tread, or more complex traces may comprise different segments having different inclinations or may comprise different curves having different curvatures. In these particular cases, the angle a is determined between the straight line passing through the two ends 13a, 13b and corresponding to an average trace of the cutout, and the transverse direction Y.

[51] Note also that the end 13a of the cutout l ia does not open here on the edge 3 tread. More particularly, the distance between this end 13a and this edge is greater than 0 and less than 10% of the width C of the tread. In this way, even if the conditions of use of the tire vary (load, inflation pressure), one keeps a coincidence of the cuts at the same circumferential level N in the tread.

[52] In the example of FIG. 2 and FIG. 11, the oblique cut-out 11a is extended at its end 13a by a generally transverse cutout extension extending to the edge 3 of the web. rolling. By "generally transverse" is meant that the cutout extension is at an angle less than 5 degrees with the transverse direction Y. The length L of the cutout extension is greater than 0 and less than 10% of the width C of the band of rolling. In a preferred embodiment, the cutout extensions extend beyond the edge 3 of the tread.

[53] FIG. 3 and FIG. 12 describe a particular embodiment in which the cutouts 11a, 11b open into a circumferential groove 4 belonging to the central zone 9 of the rolling surface 5.

[54] Figures 4 to 6 and Figures 13 to 15 describe embodiments in which each shoulder zone 7a, 7b comprises a series of cutouts 17, 19. In the embodiment of Figure 4 and Figure 13 , the series of cuts 17, 19 are symmetrical with respect to a median plane 18. Conversely in the embodiment of Figure 5 and Figure 14, the cutouts 17, 19 of the two shoulder areas are not symmetrical relative to this median plane 18. In Figure 6 and Figure 15, the series of cuts 17, 19 are offset from each other in the circumferential direction. This offset 20 is, for example, between 5 and 10 mm. Such an offset can take place in the case where the series of cutouts 17, 19 are symmetrical (FIG. 4, FIG. 6, FIG. 13 and FIG. 15) but also in the case where the series of cutouts 17, 19 are not symmetrical ( Figure 5, Figure 14). [55] Figures 7 to 9 and Figures 16 to 18 describe embodiments in which the central area 9 of the tread comprises at least one elongate block 21. This elongate block is provided with a plurality of cutouts 29a. , 29b. In FIG. 7 and FIG. 16, the cutouts 29a, 29b are distributed over the contact surface of the elongated block so that when a cutout 29a reaches a second side wall 27 of the elongated block, another cutout 29b starts from a first side wall 25 of this elongated block, at the same circumferential level M on the elongated block. In Figures 8 and 9 and Figures 17 and 18, the cutouts 29a and 29b are interrupted and extend respectively to the ends of cuts. Each cutout end is aligned with the intersection of another cutout and a sidewall of the elongate block. In FIG. 8 and in FIG. 17, the cutouts open alternately on the first side wall 25 or on the second wall In FIG. 9 and in FIG. 18, the cutouts open on one and the same first lateral wall 25.

[56] In a preferred embodiment, the series of cutouts present in the shoulder areas are circumferentially offset from the cutouts present in the elongate block.

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

[58] Thus combinations of cutouts with different inclinations, and / or different shapes and / or lengths are possible. The remarkable emergence of the noise spectrum of the tread is reduced, the interference of the sound signal emitted by the sculpture of the tire is then improved. [59] In another embodiment, it is possible to provide for the cutouts to be chamfered on the contact surface of the elongate block.

Claims

A tire made of a rubber material comprising a tread (1), said tread having a width C measured between two edges

(3) of the tread, the tread comprising a tread surface (5) intended to come into contact with a ground, the tread surface (5) comprising two shoulder zones (7a, 7b) surrounding a central zone (9), at least one of the two shoulder areas (7a, 7b) comprises a plurality of cutouts (11a, 11b) succeeding one another in a circumferential direction (X), characterized in that all or part of the cutouts (11a, 11b) of the plurality of cuts extends obliquely, each cutout having two ends (13a, 13b), and in that when a cutout (11a) reaches one of its ends (13b), another cutout ( 11b) starts at the same circumferential level (N) in the shoulder zone (7a) and in that the cuts (11a, 1b) are incisions.

2. A rubber tire comprising a tread (1), said tread having a width C measured between two edges (3) of the tread, the tread comprising a tread surface (5) for contacting a ground, the tread surface (5) comprising two shoulder zones (7a, 7b) surrounding a central zone (9), at least one of the two shoulder zones (7a, 7b) comprises a plurality of cutouts (1). 11a, 11b) succeeding one another in a circumferential direction (X), characterized in that all or part of the cutouts (11a, 11b) of the plurality of cutouts extend obliquely, each cutout having two ends (13a, 13b ), and in that when a cutout (11a) reaches one of its ends (13b), another cutout (11b) starts at the same circumferential level (N) in the shoulder zone (7a) and in that the cutouts (lia, 1 lb) are grooves.

3. A tire according to claim 1 or claim 2, characterized in that the oblique cutouts (11a, 11b) make an angle α with a transverse direction. (Y), said angle a being between 30 degrees and 60 degrees.

4. A tire according to one of claims 1 to 3, characterized in that the oblique cutouts (11a) are extended by generally transverse cutoff extensions (15), said cutoff extensions (15) extending from ends (13a) of oblique cutouts proximal to an edge (3) of the tread, and in that the length (L) of the cutout extensions is less than 10% of the width C of the tread.

5. A tire according to one of claims 1 to 4, characterized in that the oblique cutouts (11a) open into a circumferential groove (4) belonging to the central zone (9) of the running surface (5).

6. A tire according to one of claims 1 to 5, characterized in that each shoulder zone (7a, 7b) comprises a series of oblique cuts (17, 19) and in that the series of cuts (17, 19) of two shoulder areas are symmetrical with respect to a median plane (18).

7. A tire according to one of claims 1 to 6, characterized in that each shoulder zone (7a, 7b) comprising a series of oblique cutouts (17, 19) and in that the series of cutouts (17, 19) of two shoulder areas are not symmetrical with respect to a median plane (18).

8. A tire according to one of claims 6 to 7, characterized in that the two series (17, 19) of oblique cuts are offset from each other in the circumferential direction (X).

9. A tire according to one of claims 1 to 8, characterized in that the central zone (9) of the tread (1) comprises at least one elongated block (21) in the circumferential direction (X), the block elongate having a contact surface (23) for engaging a floor and a first side wall (25) and a second side wall (27) defining said contact surface, the elongate block having a plurality of cutouts (29a, 29b) opening on the block contacting surface, each cutout (29a, 29b) extending in an oblique direction opening onto the first sidewall (25) and the second sidewall ( 27), the cutouts of the block being oriented in the same direction and in that the cuts (29a, 29b) are distributed over the contact surface of the elongate block so that when a cutout (29a) reaches the second side wall ( 27) another cutout (29b) starts from the first sidewall (25) at the same circumferential level (M) on the elongated block (21).

10. A tire according to one of claims 1 to 9, characterized in that the central zone (9) comprises at least one elongated block (21) in the circumferential direction (X) of width W and length L with L »W the elongated block (21) having a contact surface (23) for contacting a floor and a first side wall (25) and a second side wall (27) defining said contact surface (23), the block elongated member (21) having a plurality of oblique cutouts (29a, 29b) alternately opening on the first side wall (25) or the second side wall (27) and extending to cut ends (31a, 31b) which do not open on said sidewalls (25, 27), characterized in that the cutouts of the plurality of cutouts (29a, 2b) succeed one another longitudinally on the contact surface (23) of the block so that when a cutout ( 29a), opening on the first side wall e (25) reaches its cutout end (31a), another cutout (29b) starts from the second sidewall (27) at the same circumferential level (M) on the elongated block (21).

11. A tire according to one of claims 1 to 10, characterized in that the central zone (9) comprises at least one elongate block (21) in the circumferential direction (X) of width W and length L with L »W the elongated block (21) having a contact surface (23) for contacting a floor and a first side wall (25) and a second side wall (27) defining said contact surface (23), the block elongate member (21) having a plurality of longitudinally successive cut-outs (29a, 29b) opening onto the contact surface (23) of the elongated block, the cutouts (29a, 29b) extending in an oblique direction from the first side wall (25) towards the second side wall (27) to cut ends (31a, 31b) characterized in that for at least one cutout (29a) opening onto the first side wall (25), its end (31a) does not open on the second side wall (27) and in that when this cutout (29a) reaches its cutout end (31a) another cutout (29b) starts from the first side wall (25a). ), at the same circumferential level (M) on the elongated block (21).

12. A tire according to one of claims 9 to 11, characterized in that the elongated block (3) is a rib.