EP2723586A1

EP2723586A1 - Tyre provided with sound channels

Info

Publication number: EP2723586A1
Application number: EP12738518.5A
Authority: EP
Inventors: Antoine Paturle
Original assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Current assignee: Michelin Recherche et Technique SA Switzerland; Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Priority date: 2011-06-23
Filing date: 2012-06-22
Publication date: 2014-04-30
Also published as: BR112013031519A2; CN103619613A; JP2014516872A; FR2976852B1; WO2012175893A1; FR2976852A1; US20140130948A1

Abstract

The invention relates to a tyre including at most 30 channels (23A, 23B) distributed substantially evenly around the circumference of the tyre. Each channel (23A, 23B) is arranged so as to fulfil the following conditions beyond a predetermined wear threshold: A) the channel (23A, 23B) is leads into a design element of the tyre, and B) the channel (23A, 23B) includes an opening (36A) that radially opens to the outside of the tyre (10) and is defined by at least two ridges (34A) capable of engaging with the ground upon becoming part of the contact area between the tyre (10) and the ground, the circumferential distance (LcA) separating the ridges (34A) from one another being no less than 2 mm and preferably 4 mm, wherein below the predetermined threshold, the channel does not fulfil at least one of conditions A and B.

Description

Pneumatic with sound channels

[01] The present invention relates to a tire provided with sound wear indicators. It applies in particular, to be restricted to tires for vehicles of any type, tourism or trucks.

[02] As a tire rolls on a ground, its tread that is in contact with the ground wears by friction. For obvious safety reasons, it is important to replace a tire before the tread wear is too great and may impact its performance, particularly its grip on wet roads.

[03] Document FR 2 937 902 discloses a tire comprising equi-distributed sound wear indicators constituted by sound cavities. Each cavity is delimited in part by two bars arranged at the bottom of a groove of the tire. Each cavity is shaped so as to be closed by the ground in a substantially watertight manner so as to temporarily trap air as it passes through the contact area of the tire with the ground. Under the effect of the deformation of the tire in the contact area, this air trapped in the cavity compresses and then suddenly relaxes at the exit of the contact area and therefore the cavity opens. This expansion of the air causes a characteristic noise that appears only when the tire is worn beyond a certain threshold. Thus, even if the driver does not regularly oblige to visually inspect the surface condition of his tires, he is informed of the excessive wear of his tires when, while driving, the characteristic noise is detected.

[04] However, the sound cavities, because of the arrangement of the bars in the grooves, can degrade the performance of the tire with respect to a tire without such sound cavities, especially in terms of evacuation of water by the grooves and therefore adhesion, mainly because of the large number of bars used to delimit the different cavities. This degradation of the water evacuation performance is even greater than the wear of the tire is advanced.

[05] In addition, the design of the tire and its mold is complex, in particular because of the large number of bars used to delimit the different cavities. Indeed, in the case where a witness is located at the same position as an element of the sculpture such as an open cutout opening into the cavity defined by the two bars, the cavity does not emit the expected noise, because it is not closed so as to trap air, and therefore does not detect wear. On the other hand, if a strip is located at the same position as a particular area of the mold, such as the seal between two sectors, the mold member for molding the bar is weakened mechanically due to the many openings and closures of the mold. If, moreover, we want to respect the equi-distribution of the witnesses, it then becomes difficult, if not impossible, to conceive empirically a tire in which all the wear indicators satisfy these constraints of interaction with the elements of sculpture and mold.

[06] The invention aims in particular to provide a tire with sound wear indicators having little influence on the performance and design of the tire.

[07] For this purpose, the subject of the invention is a tire comprising at most

30 channels substantially equi-distributed circumferentially on the tire, each channel being arranged so that:

a) beyond a predetermined wear threshold, it satisfies the following conditions: A: the channel opens into a tire trimming element, preferably axially and / or in a circumferential groove, and

B: the channel comprises a mouth opening radially outwardly of the tire and delimited by at least two edges capable of coming into contact with the ground during their passage in the contact area of the tire with the ground, the circumferential distance separating the edges of each other being greater than or equal to a value D, this value D being greater than or equal to 2 mm and preferably 3 mm, and very preferably 4 mm

b) below this predetermined wear threshold (SA1, SB1), it does not satisfy at least one of the conditions A and B.

In other words, there is a wear threshold higher than the predetermined threshold such as between the predetermined threshold and this higher threshold, the tire satisfies the conditions A and B. In addition, there is a threshold of less wear than the predetermined threshold such as between this lower threshold and the predetermined threshold, the tire does not check at least one of the conditions A and B.

[08] Such channels generate, during their passage through the contact area of the tire with the ground, a characteristic noise during the rolling of the tire once the wear threshold of the tire reaches. The inventors put forward the hypothesis according to which this noise is generated by at least three distinct physical phenomena having a synergistic effect.

[09] On the one hand, once the wear threshold is reached, the noise is generated by the impact of each edge on the ground. Conversely, when the circumferential distance is less than a value D, for example equal to 2 mm, or 2.5 mm, or 3 mm, or even 4 mm depending on the type of tire, the edges come into contact with each other during their passage through the contact area of the tire with the ground due to the elasticity of the rubber. The mouth being then closed, generates a very low impact noise that is difficult to detect and exploitable.

[010] On the other hand, once the wear threshold is reached, the channel is covered by the ground during its passage in the contact area. Thus covered, the channel forms a pipe which resonates because of the vibrations induced by the aforementioned impact edges forming the edges of the pipe during the rolling of the tire on the ground. The resonance then causes a resonance noise characterized by a frequency range centered on a resonance frequency depending on the length of the channel (characteristic almost independent of the running speed) but whose amplitude changes as a function of the section of the pipe which it itself evolves according to the wear of the tire.

[01 1] Finally, the noise generated by the channel is amplified by acoustic coupling with the tire sculpture network because the channel opens into a sculpture element. By carving element, is meant a hollow element in the tread, for example a notch, a groove or a strip, as opposed to a raised element, for example a gum roll.

[012] By circumferential distance separating the two edges, the average distance between the two edges along the path along which the channel extends. Thus, in the case where the edges are substantially parallel to each other along the path along which the channel extends, the circumferential distance is the distance separating, in the circumferential direction of the tire, the two edges. In the case where the edges are not parallel to each other along the path along which the channel extends, the circumferential distance separating the two edges is the average, along the path along which the channel, distances separating, in the circumferential direction of the tire, the two edges.

[013] In the invention, each wear indicator consisting of a channel and not two projections forming a cavity closed to air during its passage in the contact area of the tire with the ground, it is significantly reduces the potential loss of performance generated by the witnesses, or even improves the performance of water evacuation by the tire.

[014] In addition, because of the reduced number of channels, the design of the tire and its mold is also made simpler because, each control does not form a closed cavity, it is not necessary to avoid interactions with the other sculpting elements or the mold of the tire.

[015] Even if the driver does not regularly undertake to inspect visually the surface condition of its tires, it will be informed of the crossing of the wear threshold when, rolling, the characteristic noise will be detected.

In addition, since the channels are equi-distributed circumferentially around the tread of the tire, the noise emitted beyond the wear threshold has remarkable frequency characteristics. Indeed, the spectral analysis of the noise emitted beyond the wear threshold shows, in the frequency domain, a Dirac comb that can easily be identified among all the parasitic noises such as tire rolling noise. , the wind, the noise of the engine or the sound of the kinematic chain associated therewith. It will be possible to use a method for detecting the wear of the tire according to the invention as described in application PCT / FR2010 / 052584. Alternatively, other methods may be used.

[017] Preferably, one or more detection microphones, connected to a processing unit able to detect the noise among the rolling noise, the wind, the noise of the engine or the noise of the kinematic chain which is associated therewith, are used. and inform the driver of tire wear.

By "circumferentially equi-distributed channels" is meant that each channel is situated substantially at the same angular distance from the two channels that are adjacent to it, whether they are circumferentially aligned or not. In other words, the equi-distributed channels present, two by two, the same angular difference.

[019] Preferably, the circumferential distance separating the edges is less than or equal to 30 mm.

[020] Beyond a certain circumferential distance, the tire has a rate of sculptures too large to ensure sufficient rigidity.

[021] Advantageously, in the case of a tire for tourism type vehicle, the circumferential distance separating the edges is between 12 and 16 mm included terminals. In the case of a tire for a truck-type vehicle, the circumferential distance separating the ridges is between 4 and 8 mm inclusive.

[022] Such a circumferential distance can generate a sufficiently strong noise while minimizing the influence of the channels on the performance of the tire.

[023] Preferably, each channel opens axially in a circumferential groove.

[024] Even more preferably, the tire comprising two circumferential grooves, each channel opens into the two grooves, preferably axially.

[025] As the channels open into the grooves, the noise generated is amplified relative to channels that would be disposed elsewhere in the tread. The noise generated is amplified by an acoustic coupling phenomenon between the resonance of the pipes formed by the channels and the resonance of the pipes formed by the grooves.

[026] Advantageously, each channel has two mouths opening axially into the grooves, the two mouths being substantially aligned axially.

[027] Preferably, each channel extends along a substantially rectilinear path and parallel to the axial direction of the tire.

[028] The sound intensity of the impact noise is even stronger than the stop is long and its orientation perpendicular to the circumferential direction. Thus, when each channel extends along a substantially rectilinear path and parallel to the axial direction of the tire, the entirety of each edge simultaneously strikes the ground during its passage in the contact area of the tire with the ground, which allows to increase the volume of the impact sound.

[029] According to an optional characteristic of the tire, beyond the threshold, each channel and the carving element delimit a space open to air during the passage of the channel in the contact area of the tire with the ground.

[030] The resonance noise of the pipe can thus propagate in the tire tread pattern.

[031] Optionally, the tire comprises between 2 and 12 included terminal channels, typically in the case of a truck-type vehicle tire and between 2 and 8 inclusive terminal channels, typically in the case of a tire. for tourism type vehicle.

[032] In one embodiment, each channel is radially closed to the outside of the tire by a mass of rubber of the tire when the tire is new.

[033] In another embodiment, each channel opens radially outwardly of the tire when the tire is new.

[034] Preferably, each channel comprises first and second radial portions arranged so that the second radial portion extends radially outwardly of the tire the first radial portion, and such that: - the first radial portion, considered as channel, satisfies condition B;

[035] - the second radial portion, considered as a channel, does not satisfy condition B. Preferably, the circumferential distance separating the edges of the other for the second radial portion is less than 0.8 D , and very preferably at 0.6 D. Typically, this distance is less than 2 mm, or 1, 8 mm, and preferably less than 1.5 mm.

[036] Preferably, the circumferential distance between any two points of the first radial portion, corresponding to the same level of wear and vis-à-vis circumferential, is greater than or equal to D, and preferably to 4 mm, In other words, this distance between edges advantageously concerns any local distance, and not only the average distance.

[037] Preferably, the circumferential distance between any two points of the second radial portion, corresponding to the same level of wear and vis-à-vis circumferential is less than D, and preferably 2 mm. In other words, this distance between edges advantageously concerns any local distance, and not only the average distance.

[038] Advantageously, each portion has in a radial plane a rectangular shape of substantially constant section along the axial direction.

[039] Advantageously, each channel is arranged so that, beyond a threshold of wear more advanced than the threshold, it satisfies at most only one of the conditions A and B.

[040] Thus, beyond the most advanced threshold, the channels no longer generate the characteristic noise and therefore no longer form audible wear indicators. It is thus possible to detect a wear range.

[041] In one embodiment, the tire comprises first and second sets of at most 30 channels, the channels of each first and second set being equi-distributed circumferentially on the tire, each channel of each first and second set being arranged so that, beyond respectively at least first and second predetermined wear thresholds, the second threshold being more advanced than the first threshold, it satisfies the conditions A and B.

[042] The channels of the first set form audible wear indicators indicating the wear of the tire beyond the first threshold. The channels of the second set form audible wear indicators indicating tire wear beyond the second threshold.

[043] By differentiating certain characteristics of the channels of the first and second sets, in particular the number of channels of each set, it is possible to differentiate the characteristics of the noise generated by the channels beyond each threshold. Thus, for a given speed, beyond a given threshold, the noise generated by the channels associated with this given threshold has certain characteristics whereas, beyond another threshold, the noise generated by the channels associated with this other threshold has other characteristics. [044] Preferably, each channel of each first and second set is arranged such that, beyond a third and fourth wear threshold respectively more advanced than each first and second threshold, it satisfies at most only one of conditions A and B.

[045] It is thus possible to detect two wear ranges. These ranges may be distinct, that is to say, have no value of common wear or overlap, that is to say, present wear values in common.

[046] The invention will be better understood on reading the description which follows, given solely by way of non-limiting example and with reference to the drawings in which:

Figure 1A illustrates a new tire according to a first embodiment;

FIGS. 1B and 1C illustrate the tire of FIG. 1A used respectively above first and second wear thresholds; Figure 2A is a sectional view of the tire of Figure 1A according to a median radial plane of the tire;

FIGS. 2B and 2C are views similar to the view of FIG. 2A respectively of the tires of FIGS. 1B and 1C;

FIG. 3A is a view from above of the tire of FIG. 1A;

FIGS. 3B and 3C are views similar to the view of FIG. 3A respectively of the tires of FIGS. 1B and 1C;

FIG. 4 schematically illustrates a developed tread of the tire of FIGS. 1A, 1B and 1C;

- Figure 5 schematically illustrates a developed tread of a tire according to a second embodiment;

FIGS. 6A, 6B and 6C are views similar respectively to the views of FIGS. 2A, 2B and 2C of a tire according to a third embodiment;

FIGS. 7A, 7B and 7C are views similar respectively to the views of FIGS. 2A, 2B and 2C of a tire according to a fourth embodiment;

FIGS. 8A, 8B and 8C are views similar respectively to the views of FIGS. 2A, 2B and 2C of a tire according to a fifth embodiment;

Figures 9 to 12 are views similar to those of Figures 2A, 6A, 7A and 8A according to sixth, seventh, eighth, and ninth modes of production;

Figures 13 to 15 are views similar to that of Figure 3C of tires respectively according to tenth, eleventh, and twelfth embodiments.

[047] There is shown in Figure 1A a tire in the new state according to a first embodiment of the invention, designated by the general reference 10. The tire 10 is intended for a passenger vehicle. The tire 10 is substantially of revolution about an axis.

[048] The tire 10 comprises a tread 12 of substantially toroidal shape and whose outer surface is provided with 14 carving elements. In order to minimize rolling noise, in particular the siren associated with the periodicity of the tire 10, the sculpture usually comprises several distinct circumferential portions. Each circumferential portion bears a pattern selected from a group of several distinct patterns, typically three or four patterns. The sculpture thus consists of a non-periodic arrangement of these patterns so as to avoid the sirenation of the tire 10.

[049] The elements 14 comprise grooves 16, notches 17 and slats 18. Because of their shallow depth, the slats 18 are visible only in Figure 1. The tire 10 comprises two grooves 16 circumferential and parallel, hollowed on the surface of the tire, of predetermined depth H when the tire 10 is new. The depth H of these grooves 16 is of the order of 8 mm and their width is of the order of 10 mm.

[050] The tire 10 comprises a mass of rubber 20 disposed between the two grooves 16. The mass of rubber 20 forms a belt 22 extending circumferentially around the tire 10.

[051] The tire 10 comprises two sets E1, E2 respectively comprising channels 23A, 23B. Each channel 23A, 23B opens axially into at least one circumferential groove 16, in this case in the two circumferential grooves 16.

[052] FIGS. 2A and 3A show two channels 23A, 23B formed in the tread 12, in this case in the belt 22. In this and following figures, the dimensions are arbitrarily modified for the clarity of the presentation.

[053] Each channel 23A, 23B respectively comprises first 24A, 24B and second 26A, 26B radial portions. Each portion 26A, 26B extends radially outwardly of the tire each portion 24A, 24B. Each portion 26A, 26B respectively comprises a mouth 28A, 28B opening radially outwardly of the tire 10. Each channel 23A, 23B extends radially from the top S of a carcass ply 28 of the tire 10 to the surface 29 of contact with the ground of the tread 12. The distance separating the vertex S and the surface 29 is substantially equal to the height H of the grooves 16. Each channel 23A, 23B opens radially towards the inside of the tire 10 on the apex S.

[054] Each portion 24A, 24B, 26A, 26B respectively comprises two mouths 30A, 30B, 32A, 32B opening axially in the two grooves 16. Each channel 23A, 23B extends axially between the two grooves 16. Each channel 23A, 23B extends along a substantially rectilinear path and parallel to the axial direction of the tire 10. The mouths 30A, 30B and 32A, 32B are respectively substantially axially aligned with each other.

[055] Each portion 24A, 24B and 26A, 26B has, in a radial sectional plane, a constant section along the axial direction and having a rectangular shape.

[056] Each mouth 28A, 28B is delimited respectively by two edges 34A, 34B. The dimension LeA, LeB of each portion 26A, 26B in the circumferential direction, that is to say the circumferential distance separating the two edges 34 from each other, also called width, is less than or equal to 1 mm .

[057] The hcA dimension of each portion 24A in the radial direction, also called height, is greater than the height hcB of each portion 24B. The height heA of each portion 26A is less than the height heB of each portion 26B.

[058] The dimension leA, leB of each portion 26A, 26B in the axial direction, also called length, is substantially equal to the length IcA, IcB of each portion 24A, 24B. In this embodiment, heA + hcA = heB + hcB = H

[059] FIGS. 1B, 2B and 3B show the tire 10 worn beyond a threshold SA1, that is to say after the disappearance by wear of a radial thickness U1> SA1 = heA of the tread 12.

[060] Beyond the threshold SA1, each portion 24A comprises a mouth

36A opening radially outwardly of the tire 10. Each portion 24A opens into the two grooves 16 via the mouths 30A.

[061] The wear of the tire 10 shown in Figures 1B, 2B and 3B is greater than the threshold SA1, that is to say at the distance between, when the tire 10 is new, the mouth 36A of the portion 24A and the surface 29. Thus, beyond the threshold SA1, each channel 23A has a height heA + hcA-U1 less than the height hcA. [062] Beyond the threshold SA1, each channel 23A and the grooves 16 define an open space to the air during the passage of the channel 23A in the contact area of the tire with the ground.

[063] Beyond the threshold SA1, each mouth 36A is delimited by two edges 38A able to come into contact with the ground during their passage through the contact area of the tire 10 with the ground. The width LcA of each channel 23A, that is to say the circumferential distance separating the two edges 38 from one another, is greater than or equal to 2 mm and preferably 4 mm. LcA is also less than or equal to 30 mm. In this case, LcA is between 12 and 16 mm inclusive and is 14 mm.

[064] There is shown in Figures 1C, 2C and 3C the tire 10 worn beyond a threshold SB1 more advanced than the threshold SA1, that is to say after the disappearance by wear of a thickness radial U2> SB1 = heB of the tread 12.

[065] Beyond the threshold SB1, each channel 23B comprises a mouth 36B opening radially outwardly of the tire 10. Each channel 23B opens axially into the two grooves 16 via the mouths 30B. Each channel 23A also opens radially towards the outside of the tire via the mouth 36A and axially in the two grooves 16 via the mouths 30A.

[066] The wear of the tire 10 shown in Figures 1C, 2C and 3C is greater than the threshold SB1, that is to say at the distance between, when the tire 10 is new, the mouth 36B of the portion 24B and the surface 29. Thus, beyond the threshold SB1, each channel 23A, 23B has a height heB + hcB-U2 less than the height hcB.

[067] Beyond the threshold SB1, each channel 23A, 23B and the grooves 16 define an open space in the air during the passage respectively of the channel 23A, 23B in the contact area of the tire with the ground.

[068] Beyond the threshold SB1, each mouth 36B is delimited by two edges 38B able to come into contact with the ground during their passage through the contact area of the tire 10 with the ground.

[069] Beyond threshold SB1, each width LcA, LcB of each channel 23A,

23B, that is to say the circumferential distance separating respectively the two edges 38A, 38B from one another, is greater than or equal to 2 mm and preferably 4 mm. Each width LcA, LcB is also less than or equal to 30 mm. In this case, each width LcA, LcB is between 12 and 16 mm inclusive and LcA = LcB = 14mm.

[070] Each channel 23A, 23B is arranged so that, beyond respectively a threshold SA2, SB2 more advanced respectively than each threshold SA1, SB1, it satisfies at most only one of the following conditions:

the channel 23A, 23B opens into at least one of the grooves 16 (condition A), and

the channel 23A, 23B comprises a mouth 36A, 36B opening radially outwardly of the tire 10 and delimited by at least two edges 38A, 38B able to come into contact with the ground during their passage through the contact area of the tire 10 with the ground, the circumferential distance LcA, LcB separating the edges 38A, 38B from each other being greater than or equal to 2 mm and preferably 4 mm (condition B).

[071] When the tire 10 has a wear greater than the thickness H of the tread 12 (not shown), the tire is worn beyond the wear threshold SA2, SB2. In this embodiment, SA2 = SB2. This wear corresponds to the disappearance of a radial thickness U3> H of the tread 12.

[072] Beyond the threshold SA2, SB2 and when the tire 10 has the wear U3, none of the channels 23A, 23B satisfies the condition A nor the condition B. Indeed, the channels 23A and 23B disappear.

[073] Note that whatever the wear of the tire 10, each portion 26A, 26B satisfies at most one of the conditions A and B, in this case the condition A.

[074] Figure 4 illustrates the circumferential distribution of the channels 23A, 23B. The tire 10 comprises at most 30 channels 23A, 23B, that is to say between 2 and 30 inclusive terminal channels. In this case, the tire 10 comprises between 2 and 8 inclusive terminal channels, here 6 channels. The set E1 comprises 3 channels 23A. The set E2 comprises 3 channels 23B. In a variant, the numbers of channels 23A, 23B of the sets E1, E2 are different from each other.

[075] The channels 23A are substantially equi-distributed circumferentially on the tire 10, as well as the channels 23B. Moreover, all the channels are evenly distributed circumferentially on the tire. All channels 23A are identical. All 23B channels are identical.

[076] There is shown schematically in Figure 5 a tread 12 of a tire according to a second embodiment. Elements similar to those shown in the preceding figures are designated by identical references.

[077] The tire 10 is for a vehicle type heavyweight. Unlike the tire according to the first embodiment, the tire 10 comprises between 2 and 12 enclosed terminal channels, here 10 channels. The E1 set includes 5 channels 23A. The set E2 comprises 5 channels 23B.

[078] In this embodiment, the circumferential distance LcA, LcB separating the edges 38A, 38B to each other is between 4 and 8 mm inclusive.

[079] There is shown in Figures 6A, 6B and 6C the channels 23A, 23B of a tire according to a third embodiment. Elements similar to those shown in the preceding figures are designated by identical references.

[080] In this embodiment, SB2 is more advanced than SA2.

[081] Unlike the tire according to the first embodiment, each channel 23A, 23B extends radially partially between the top S and the surface 29 of contact with the ground. In other words, heA + hcA <H and heB + hcB <H. Each channel 23A, 23B does not open on the top S.

[082] FIG. 6B shows the tire 10 worn beyond the threshold SA2, that is to say after the disappearance of a radial thickness U1> SA2 = heA + hcA of the tread 12. However, the wear U1 is below the threshold SB1 = heB.

[083] Above threshold SA2 and when the tire has wear U1, each channel 23A has disappeared and no channel 23A satisfies condition A or B.

[084] The threshold SB1 is more advanced than the threshold SA2, that is to say, heA + hcA <heB. Thus, when the tire 10 has the wear corresponding to the disappearance of a radial thickness U1 satisfying U1> SA1 = heA and U1 <SB1 = heB, no channel 23A, 23B satisfies the conditions A and B.

[085] FIG. 6C shows the tire 10 worn beyond the threshold SB1, that is to say after the disappearance of a radial thickness U2> SB1 = heB of the tread 12.

[086] Beyond threshold SB1 and when the tire has wear U2, each channel 23B satisfies both conditions A and B.

[087] When the tire is worn beyond the threshold SB2 (not shown), that is to say after the disappearance of a radial thickness U1> SB2 = heB + hcB of the tread 12, all 23B channels having disappeared, no 23B channel satisfies conditions A or B.

[088] There is shown in Figures 7A, 7B and 7C the channels 23A, 23B of a tire according to a fourth embodiment. Elements similar to those shown in the preceding figures are designated by identical references.

[089] Unlike the tire according to the third embodiment, each channel 23A and 23B respectively comprises three portions 24A, 26A, 27A and 24B, 26B, 27B. Each portion 24A, 24B is interposed radially respectively between the portions 26A, 27A and 26B, 27B. [090] Each portion 27A, 27B has a length leA ', leB' and a width LeA ', LeB' substantially equal to those portions 26A, 26B. Each portion 27A, 27B has a height heA, heB '. Whatever the wear of the tire 10, each portion 27A, 27B satisfies at most one of the conditions A and B, in this case the condition A.

[091] Unlike the tire according to the third embodiment, beyond the threshold SA2, the circumferential distance LeA 'separating the edges 34A' from each other is less than or equal to 4 mm and even 2 mm . None of the channels 23A then satisfies condition B.

[092] Similarly, beyond the threshold SB2 (not shown), the circumferential distance LeB 'separating the edges 34B' from each other is less than or equal to 4 mm and even 2 mm. None of the channels 23B then satisfies condition B.

[093] FIGS. 8A, 8B and 8C show the channels 23A, 23B of a tire according to a fifth embodiment. Elements similar to those shown in the preceding figures are designated by identical references.

[094] Unlike the tire according to the third embodiment, each channel 23A extends from the top S to the surface 29 of contact with the ground of the tread 12. In this embodiment, SA2 is therefore more advanced than SB2.

[095] Thus, for wear corresponding to the disappearance of a radial thickness U1 satisfying U 1> SA1 = heA and U1 <SB1 = heB (not shown), only each channel 23A satisfies the conditions A and B.

[096] FIG. 8B shows the tire 10 worn beyond the threshold SB1, that is to say after the disappearance of a radial thickness U2> SB1 = heB of the tread 12. the wear U2 is lower than the threshold SB2 = heB + hcB.

[097] Beyond threshold SB1 and when the tire has wear U2, each channel 23A, 23B satisfies conditions A and B.

[098] FIG. 8C shows the tire 10 worn beyond the threshold SB2, that is to say after the disappearance of a radial thickness U3> SB2 = heB + hcB of the tread 12.

[099] Beyond the threshold SB2 and when the tire 10 has the wear U3, only each channel 23A satisfies the conditions A and B. The 23B channels having disappeared, no channel satisfies the condition A or B.

Figures 9 to 12 show new tires according to different embodiments. Elements similar to those shown in the preceding figures are designated by identical references. The tire 10 according to the sixth embodiment of Figure 9 comprises channels 23 comprising a portion 24 having, in the radial sectional plane, a section having a teardrop shape.

The tire 10 according to the seventh embodiment of FIG. 10 comprises channels 23 radially closed towards the outside of the tire 10 by a mass of tire rubber 42 interposed radially between each channel 23 and the surface 29. Thus, when the tire has a wear below threshold SA1, each channel 23 does not satisfy condition B.

[0103]

The tire 10 according to the eighth embodiment of FIG.

1 1 comprises channels 23 comprising a portion 24 having, in the radial sectional plane, a section having a circular shape.

The tire 10 according to the ninth embodiment of FIG.

12 comprises channels 23 arranged so that beyond the threshold SA1 and before the threshold SA2, they satisfy the conditions A and B. The channels 23 are also arranged so that beyond a threshold SA3 more advanced that the threshold SA2, the channels 23 satisfy the conditions A and B and so that beyond a threshold SA4 more advanced than the threshold SA3, the channels 23 satisfy at most one of the conditions A and B.

In this case, the channel 23 comprises two radial portions 24 ^ 24 ₂ along which conditions A and B are satisfied and three radial portions 26 ₁ , 26 ₂ , 26 ₃ along which at most one of the conditions A and B is satisfied. The 26i portion corresponds to a lower wear SA1, the 24-i serving is at a wear between SA1 and SA2, the portion 26 ₂ corresponds to a wear between SA2 and SB1, the portion 24 ₂ corresponds to a wear between SB1 and SB2 and the portion 26 ₃ corresponds to a wear greater than SB2.

Figures 13 to 15 show channels 23A, 23B of tires according to different embodiments. Elements similar to those shown in the preceding figures are designated by identical references.

The tire 10 according to the tenth embodiment of FIG. 13 comprises channels 23A, 23B extending in a non-rectilinear path, in this case curved.

The tire 10 according to the eleventh embodiment of Figure 14 comprises channels 23A, 23B extending in a substantially rectilinear path in a direction forming a non-zero angle with the axial direction of the tire 10. The section of the channels 23A, 23B in a sectional plane perpendicular to the direction in which the channels 23A, 23B extend is substantially constant. The tire 10 according to the twelfth embodiment of FIG. 15 comprises channels 23A, 23B whose distance separating the edges 38A, 38B from one another is non-constant along the axial direction. Thus, the circumferential distance LcA is calculated by averaging, along the axial direction, the circumferential distances LcA ^ LcA ₂ , LcA ₃ , .... separating, for a given axial dimension, two circumferentially aligned points of the edges 38A. . The same is true for the circumferential distance LcB.

[01 1 1] The invention is not limited to the previously described embodiments.

[01 12] Indeed, we can mix the characteristics of the various embodiments described above as long as they are compatible with each other.

[01 13] Not all channels of the same set are necessarily identical. Indeed, it suffices that each channel satisfies the conditions A and B, whatever the other characteristics of the channel, in particular its general shape.

[01 14] Each channel may have a variable section along the axial direction.

The sculpture element may be a notch, preferably forming a network with other tire tread elements.

Claims

1. Pneumatic tire (10), characterized in that it comprises at most 30 channels (23A, 23B) substantially equi-distributed circumferentially on the tire, each channel (23A, 23B) being arranged so that:

a) beyond a predetermined wear threshold (SA1, SB1), it satisfies the following conditions:

A: the channel (23A, 23B) opens into a tire carving element (16), preferably axially and / or in a circumferential groove, and

B: the channel (23A, 23B) comprises a mouth (36A, 36B) opening radially outwardly of the tire (10) and delimited by at least two ridges (34A, 34B) able to come into contact with the ground when passing through the contact area of the tire (10) with the ground, the circumferential distance (LcA, LcB) separating the edges (34A, 34B) from each other being greater than or equal to a value D, this D value being greater than or equal to 2 mm and preferably 4 mm.

2. The tire of claim 1, wherein D = 2 mm.

3. A tire according to one of claims 1 or 2, comprising two circumferential grooves (16), each channel (23 A, 23 B) opening in these two circumferential grooves (16), preferably axially.

4. A tire (10) according to claim 3, wherein each channel (23A, 23B) has two mouths (30A, 30B) opening axially in the grooves (16), the two mouths (30A, 30B) being substantially axially aligned.

The tire (10) of claim 4 wherein each channel (23A, 23B) extends in a substantially straight path parallel to the axial direction of the tire (10).

Tire (10) according to any one of claims 1 to 5, wherein each channel (23A, 23B) comprises first and second radial portions (24A, 24B, 26A, 26B) arranged so that the second radial portion (26A, 26B) extends radially outwardly of the tire the first radial portion (24A, 24B), and such that:

the first radial portion (26A, 26B), considered as a channel, satisfies condition B; the second radial portion (26A, 26B), considered as a channel, does not satisfy condition B.

Pneumatic tire according to claim 6, wherein:

the circumferential distance between any two points of the first radial portion (24A, 24B), corresponding to the same level of wear and in circumferential vis-à-vis, is greater than or equal to D, and preferably to 4 mm,

the circumferential distance between any two points of the second radial portion (26A, 26B), corresponding to the same level of wear and vis-à-vis circumferential, is less than D, and preferably 2 mm.

8. A tire (10) according to claim 7, wherein each radial portion (24A, 24B, 26A, 26B) has in a radial plane a rectangular shape of substantially constant section along the axial direction.

9. A tire (10) according to any one of claims 1 to 5, wherein each of the channels (23) is radially closed towards the outside of the tire (10) by a mass of rubber (42) of the tire interposed radially between each channel (23) and the tire surface (29).

A tire (10) according to any one of the preceding claims, wherein the circumferential distance (LcA, LcB) separating the ridges (34A, 34B) is less than or equal to 30 mm.

1 1. The tire (10) of claim 10, wherein the circumferential distance (LcA, LcB) separating the ridges (34A, 34B) is between 12 and 16 mm inclusive.

12. A tire (10) according to claim 10, wherein the circumferential distance (LcA, LcB) separating the edges (34A, 34B) is between 4 and 8 mm inclusive.

Tire (10) according to any one of the preceding claims, wherein, beyond the threshold (SA1, SB1), each channel (23A,

23B) and the carving element (16) delimit an air gap when the channel (23A, 23B) passes through the contact area of the tire (10) with the ground.

Tire (10) according to any one of the preceding claims, comprising between 2 and 12 channels (23A, 23B) included terminals, and preferably between 2 and 8 channels (23A, 23B) included terminals.

15. A tire (10) according to any one of the preceding claims, wherein each channel (23A, 23B) is arranged such that, beyond a more advanced wear threshold (SA2, SB2) than the threshold (SA1, SB1), it satisfies only one of the conditions A and B.

Pneumatic tire (10) according to any one of the preceding claims, comprising first and second sets (E1, E2) of not more than 30 channels (23A, 23B), the channels (23A, 23B) of each first and second together (E1, E2) being equi-distributed circumferentially on the tire (10), each channel (23A, 23B) of each first and second set (E1, E2) being arranged so that, beyond respectively at least first and second predetermined wear thresholds (SA1, SB1), the second threshold (SB1) being more advanced than the first threshold (SA1), it satisfies the conditions A and B.

17. Tire (10) according to the preceding claim, wherein, each channel (23A, 23B) of each first and second set (E1, E2) is arranged so that, beyond a third and fourth threshold (SA2 , SB2) respectively more advanced than each first and second threshold (SA1, SB1), it meets at most one of the conditions A and B.