WO2016050665A1

WO2016050665A1 - Tyre comprising a tread including a projecting element in a transverse groove

Info

Publication number: WO2016050665A1
Application number: PCT/EP2015/072204
Authority: WO
Inventors: Bruno Guimard; Jean-Claude-John Faure; Mathieu Vandaele
Original assignee: Compagnie Generale Des Etablissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2014-09-30
Filing date: 2015-09-28
Publication date: 2016-04-07
Also published as: FR3026347B1; FR3026347A1

Abstract

The invention relates to a tyre (1) including a tread (2) and a shoulder area (3), the tread being intended for coming into contact with a road surface in order to form a contact area (A), said tread (2) comprising a plurality of substantially transverse grooves (23) connected to the shoulder area (3) of the tyre (1). The invention is characterised in that the tread (2) comprises, in at least one of the transverse grooves (23), an element (26) that projects from a bottom (230) of said transverse groove (23) and in that, when the contact area (A) is defined by an edge (Ab), the projecting element (26) is located adjacent to said edge (Ab).

Description

TIRE COMPRISING A TREAD COMPRISING A PROTUBERANCE ELEMENT IN A TRANSVERSE GROOVE

FIELD OF THE INVENTION

[01] The present invention relates to a tire for a motor vehicle having a tread and a shoulder zone, the tread being intended to come into contact with a roadway to form a contact area, said tread comprising a plurality of substantially transverse grooves opening into the shoulder area of the tire.

STATE OF THE ART [02] A tire comprises, in a known manner, an internal carcass, a tread, a shoulder zone, a sidewall and a fastening bead on a rim. The inner carcass is composed of at least one carcass ply of rubber-coated threads. During a tire manufacturing step, this carcass ply is cut and assembled on a drum. Furthermore, the carcass ply is surmounted by a plurality of vertex plies superimposed and crossed between them. The crown plies serve to stiffen the crown of the tire. The tread is laid over the top tablecloths. For each crown ply, there is a certain distance between the end of a crown ply and the edge of the flank. Due to the superposition of the crown plies between them, there is therefore a gap between the ends of the different crown plies at the border between the shoulder zone and the tread. At this boundary, the tread has a longitudinal groove which allows water to be removed from the tread. [03] A disadvantage of this state of the art lies in the fact that the border between the shoulder area and the tread has a certain fragility. Thus, if a pebble enters the transverse groove that is at the border, it can create a crack that can propagate in the tire.

DEFINITIONS

[04] "Pneumatic" means all types of elastic bandages subjected to internal pressure or not. [05] "Rubber material" means a diene elastomer, that is to say in known manner an elastomer derived from at least in part (ie homopolymer or copolymer) of monomers dienes (monomers carrying two carbon-carbon double bonds, conjugated or not).

[06] "Tread" of a tire means a quantity of rubber material delimited by lateral surfaces and by two main surfaces, one of which, called a tread surface, is intended to come into contact with a road surface. when the tire is rolling.

[07] By "sidewall" of a tire means a side surface of the tire disposed between the tread of the tire and a bead of the tire.

[08] By contact area means all the points of the tread which come into contact with the roadway at a given moment when the tire, inflated to its reference pressure rolls on this road. The reference inflation pressure is defined in the conditions of use of the tire as defined in particular by the European Tire and Rim Technical Organization (ETRTO) standard. SUMMARY OF THE INVENTION

[09] The invention relates to a rubber tire comprising a tread and a shoulder zone, said tread being intended to come into contact with a roadway to form an area of contact, said tread comprising a plurality of substantially transverse grooves opening into the shoulder area of the tire. The tread has in at least one of the transverse grooves a protruding element with respect to a bottom of said transverse groove and the contact area being delimited by an edge, the protruding element is located near this edge. The tread comprises a longitudinal groove and the protruding member is located at an intersection between said longitudinal groove and said transverse groove.

[10] The protruding element protects the bottom of the transverse groove so as to reduce the risk of cracks appearing at this level. The presence of this protruding element at the intersection avoids the retention of pebbles specifically at this location.

[11] In a non-limiting embodiment, the transverse groove comprises at least one chamfer.

[12] This makes it possible to further reduce the retention of pebbles since they will not be retained by sharp edges of the edge of said transverse groove.

[13] In a nonlimiting embodiment, the tread comprising at least one wear indicator of height H, the protruding element has a mean height less than the height of the wear indicator and greater than 0, 5 mm. [14] With such a height, the protruding element can be used as a wear indicator for an observer of the tire. The latter can thus check the state of wear of the tire at the shoulder area. Indeed, as a wear indicator, the protruding element is more visible than the regulatory wear indicators which are located in the center of the tread. The protruding element as a wear indicator is thus complementary to the prescribed wear indicators in order to improve the overall verification of the state of the tire by the observer. The height of the wear indicator is less than the height of the statutory wear indicators (at least 1, 6 mm) to take into account the uses observed and possibly the degression of the depth of sculpture to nine of the tire. In fact, at the contact edge, the height of the rubber is generally lower than the height of the rubber in the center of the tread.

[15] In a non-limiting embodiment, the average height of the protruding element is between 0.6 and 1mm.

[16] This improves wear reading by the user via the protruding element.

[17] In a non-limiting embodiment, the protruding element has a streamlined shape.

[18] This makes it easier to evacuate the water in said transverse groove.

[19] In a nonlimiting embodiment, the tread comprises a plurality of protuberance elements regularly distributed over the circumference of the tire.

[20] This allows an observer of the tire to easily check the tire as a whole if the tire begins to wear.

[21] In a non-limiting embodiment, the transverse groove flares towards the shoulder zone of the tire.

[22] This allows better evacuation of water around the protruding element.

[23] In a non-limiting embodiment, the transverse groove comprises a bridging at the intersection between said transverse groove and the groove longitudinal, said bridging having an inclined face extending from said intersection towards the shoulder zone of the tire.

[24] This allows better evacuation of water.

[25] In a non-limiting embodiment, the bridging comprises an incision on the inclined face.

[26] This provides a less rigid transverse groove. Flattening said tire is thus facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

[27] Other features and advantages of the invention will become apparent from the following description, given by way of example, without limitation, with reference to the accompanying drawings, in which: FIG. 1 schematically represents a section of a tire comprising a tread and a shoulder zone according to the invention according to a non-limiting embodiment; Figure 2 schematically shows a top view of the tire of Figure 1; Figure 3 shows a perspective view of a transverse groove of the tire of Figure 1 according to a first non-limiting embodiment; FIG. 4 represents a perspective view of a transverse groove of the tire of FIG. 1 according to a second nonlimiting embodiment; - Figure 5 shows a perspective view of a transverse groove of the tire of Figure 1 according to a third non-limiting embodiment; FIG. 6 represents a sectional view A - A 'of a portion of the tire of FIG. 2 according to a first nonlimiting embodiment; FIG. 7 represents a sectional view A - A 'of a portion of the tire of FIG. 2 according to a second nonlimiting embodiment; Figure 8 shows the transverse groove of Figure 3 with an additional incision; Fig. 9 shows the transverse groove of Fig. 4, with an additional incision; Figure 10 shows the transverse groove of Figure 5, with an additional incision.

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

[29] Figure 1 shows a sectional view of a tire 1 comprising a tread 2, a shoulder zone 3 and a sidewall 4. The shoulder zone 3 is a transition zone between the sidewall 3 and the tread 2. The shoulder zone 3 is not intended to come into contact with a roadway. The tread 2 is intended to come into contact with a roadway to form a contact area A.

[30] In FIG. 1 are also illustrated the attachment bead 10 with a rim, a carcass ply 11 and two crown plies 12 and 13. [31] The tread 2 has a plurality of longitudinal grooves 21, 22 (FIG. also called circumferential grooves or sculptures). The longitudinal grooves referenced 22 are the grooves which are on the edges Ab of the contact area A, namely at the boundary between the tread 2 and the shoulder zone 3.

[32] As illustrated in the top view of Figure 2, the tread 2 also has a plurality of substantially transverse grooves 23 opening into the shoulder zone 3 of the tire. By substantially transverse means that a groove 23 is disposed at plus or minus 20% relative to a direction parallel to the axis of rotation of the tire 1. The tread 2 further comprises at least one wear indicator 25. In the non-limiting example illustrated, it includes two witnesses 25 These wear indicators 25 are located at the bottom of longitudinal grooves 21 and have a height H of 1.6 mm. They are in the center of the tread 2 at the contact area A.

[33] The contact area A is illustrated in FIG. 2. It comprises a maximum width C defined by the ETRTO standard which is equal to C = (1.075-0.005 ar) * S ^{1 001} with ar the nominal ratio of appearance and s the size of the theoretical rod on the measuring rim.

[34] Moreover, the tread 2 comprises in at least one of the transverse grooves a protruding element 26 with respect to a bottom 230 of said transverse groove 23. The contact area A being delimited by an edge Ab, protruding element 26 is located near this edge Ab. By proximity means that the center 260 of the protruding element 26 is located within plus or minus 5% of this edge Ab. In FIG. non-limiting example shown, the center 260 is located exactly on one of the edges Ab. [35] This protruding element 26 serves as an indicator of tire wear. Thus, an observer of the tire 1 can easily check whether the tire 1 begins to wear while observing the tire at the shoulder zone 3.

[36] So that the observer does not waste time looking for the protruding element 26, in a non-limiting embodiment, the tread 2 has a plurality of protuberance elements 26 regularly distributed on the circumference of the pneumatic 1 and in particular in different transverse grooves 23.

[37] The protruding element 26 has an average height h1 less than the height H of the wear indicator 25 and greater than 0.5 mm. This protruding element which is thus at the boundary between the shoulder zone 3 and the tread 2 is thus more easily visible than the wear indicators 25 which are in the center of the tread 2.

[38] In a non-limiting embodiment, the average height hl of the protruding element 26 is between 0.6 and 1mm. This value range is sufficient to allow an observer of the tire to observe the wear of the tire.

[39] As can be seen in Figure 2 or Figure 3, in a non-limiting embodiment, the protruding element 26 has a streamlined shape. The protruding element is thus hydrodynamic since it allows the water to flow easily, unlike a rectangular or square shape, for example. This shape is hydrodynamic in the flow direction from the transverse groove. In another non-limiting embodiment, the protruding element 26 may have a triangle shape with a vertex of the triangle oriented towards the center of the tread 2 and the base of the triangle facing the shoulder zone. This orientation facilitates the flow of water towards the outside of the contact area.

[40] Similarly, in order to allow a better evacuation of the water especially around the protruding element 26, in a non-limiting embodiment, the transverse groove 23 flares towards the shoulder zone 3 of the tire 1 as illustrated in Figure 2.

[41] When the tire 1 rolls on the roadway, pebbles can be inserted in the various longitudinal grooves 21,22 and the transverse grooves 23 of the tire 1 and in particular pebbles can become jammed more easily in an intersection between a groove longitudinal 21,22 and a transverse groove 23, especially at the beginning of life of the tire. The retention of pebbles in these intersections can lead to cracking in the grooves.

[42] In order to avoid as much as possible the retention of pebbles, several means are used and are described below.

[43] In a non-limiting embodiment illustrated in Figure 2 and Figure 4, the protruding member 26 is located at an intersection between the longitudinal groove 22 and the transverse groove 23 in which the protuberance element 26 is willing. Element 26 thus prevents pebbles from getting stuck at the intersection where it is located.

[44] In a non-limiting embodiment, the transverse groove 23 comprises at least one chamfer 231. As illustrated in FIG. 5, the transverse groove 23 comprises two chamfers 231. This further reduces the retention of pebbles. The chamfer 231 which is located at the intersection also eliminates sharp edges at the intersection, sharp edges which are mechanically fragile. This chamfer can have a complex geometry: variable height, with or without additional curvature.

[45] Fig. 5 illustrates an embodiment in which the transverse groove 23 comprises the bevel 231 and wherein the protrusion member 26 is located at an intersection between said longitudinal groove 22 and said transverse groove 23.

[46] In order to reinforce the mechanical strength of the transverse groove 23, in a non-limiting embodiment, the transverse groove 23 comprises a bridging 232 at the intersection between said transverse groove 23 and the longitudinal groove 22, said bridging 232 having an inclined face 233 extending from said intersection towards the shoulder zone 3 of the tire 1. The bridging thus has a profile in the form of a slide. The bridging 232 is illustrated in the sectional view A-A 'of FIG. 6. [47] The bridging 232 is an attached rubber element which makes it possible to bind the two faces facing each other 234 and 235 of the groove 23. The inclined face 233 of the bridge 232 makes it possible to evacuate the water easily.

[48] In a first non-limiting embodiment illustrated in Figure 6, the inclined face 233 of the bridge 232 is straight. [49] In a second non-limiting embodiment illustrated in Figure 7, the inclined face 233 of the bridge 232 is curved.

[50] In order to obtain a less rigid transverse groove 23 so as to facilitate the flattening of the tire 1, in a non-limiting embodiment, the bridging 232 comprises an incision 24 on the inclined face 233 as illustrated on FIG. FIGS. 8 to 10. As shown, the incision 24 is disposed at the center of the bypass 232 and stops in front of the protrusion element 26. It will be noted that the depth of the incision 24 is less than the depth h2 of the transverse groove 23.

[51] FIG. 8 illustrates the embodiment of the transverse groove 23 of FIG. 3 with the additional incision 24, an embodiment in which the element protuberance 26 is not located at an intersection between the transverse groove 23 in which it is located and a longitudinal groove 22.

[52] FIG. 9 illustrates the embodiment of the transverse groove 23 of FIG. 4 with the additional incision 24, an embodiment in which the protruding element 26 is located at an intersection between the transverse groove 23 in which it is located and a longitudinal groove 22.

[53] FIG. 10 illustrates the embodiment of the transverse groove 23 of FIG. 5 with the additional incision 24, an embodiment in which said transverse groove 23 comprises a chamfer 231. [54] The invention is not not limited to the examples described and represented and various modifications can be made without departing from its scope.

Thus, in a non-limiting embodiment, the bridging has a completely domed shape.

Thus, in a non-limiting embodiment, the transverse groove that supports the protruding element may comprise a chamfer without the protruding element being located at an intersection between said transverse groove and a longitudinal groove.

Thus, in a non-limiting embodiment, the transverse groove that supports the protruding element may comprise a chamfer and a bridge with an incision without the protruding element being located at an intersection between said transverse groove and a groove. longitudinal.

[55] Thus, the invention described has the following advantages in particular: it provides an additional means for an observer of the tire to monitor the wear on the tire; it provides a wear indicator that is easier to access than the prescribed wear indicators. In fact, if an observer uses only the wear indicators, he may have to move his vehicle to observe these witnesses. of wear, which is not the case with the wear indicator since it is in an area easily accessible to the eye; the addition of a protuberance element as an indicator of wear in a transverse groove does not prevent the flow of water in said transverse groove; the addition of a protruding element as an indicator of wear in a transverse groove limits the retention of pebbles in said transverse groove, and thus prevents the appearance of cracks which could propagate in the tire. The robustness of the tire is thus improved, and the safety of a user of the vehicle is also improved.

Claims

1. A tire (1) made of rubber material comprising a tread (2) and a shoulder zone (3), the tread being intended to come into contact with a road surface to form a contact area (A), said tread tread (2) comprising a plurality of substantially transverse grooves (23) opening into the shoulder zone (3) of the tire, characterized in that the tread (2) comprises in at least one of the transverse grooves an element (26) protruding with respect to a bottom (230) of said transverse groove (23) and in that the contact area (A) is delimited by an edge (Ab), the protruding element (26) is located in the vicinity of this edge (Ab) and in that, the tread comprising a longitudinal groove (22), the protruding element (26) is located at an intersection between said longitudinal groove (22) and said transverse groove (23). .

2. A tire according to claim 1, characterized in that the transverse groove (23) comprises at least one chamfer (231).

3. Tire (1) according to one of claims 1 or 2, characterized in that, the tread (2) comprising at least one wear indicator (25) of height H, the protruding element (26 ) has a mean height (hl) less than the height H of the wear indicator (25) and greater than 0.5 mm.

4. A tire (1) according to any one of claims 1 to 3, characterized in that the average height (hl) of the protruding element (26) is between 0.6 and 1mm.

5. Pneumatic tire (1) according to any one of claims 1 to 4, characterized in that the protruding element (26) has a streamlined shape.

6. Tire (1) according to any one of claims 1 to 5, characterized in that the tread (2) comprises a plurality of protruding elements (26) regularly distributed over the circumference of the tire (1).

7. A tire (1) according to any one of claims 1 to 6, characterized in that the transverse groove (23) flares towards the shoulder area (3) of the tire (1).

8. A tire (1) according to any one of claims 1 to 7, characterized in that the transverse groove (23) comprises a bridge (232) at the intersection between said transverse groove (23) and the longitudinal groove (22), said bridge (232) having an inclined face (233) extending from said intersection towards the shoulder area (3) of the tire (1).

9. Tire (1) according to any one of claims 1 to 8, characterized in that the bridging (232) comprises an incision (24) on the inclined face.