FR2638125A1 - High performance tyres with a radial carcass, inflated to a high internal pressure, with cuts in the shoulders - Google Patents

Abstract

The invention relates to high performance tyres with a radial carcass, inflated to a high internal pressure. In such a tyre including a carcass 1, a bracing ply 2 having several layers of crossed cords 4, 5, 6, a tread strip 3 and cuts 10 made in each shoulder of the tread strip at a given spacing in the circumferential direction of the tyre, at least one end part of these cuts 10, located close to one lateral edge of the outermost layer 4 of the bracing ply, extends in the same direction as that in which the cords of the layer 4 extend with respect to the equatorial plane of the tyre. Application particularly to tyres of vehicles, particularly for underground trains or electric trains.

Description

 The present invention relates to high-performance radial-ply tires inflated to a high internal pressure of 9 -102.105 Pa, and more particularly to a high-performance radial-ply tire inflated to a high internal pressure and capable of preventing very effectively the appearance of what is called a tear in the notches, in the case of the application of the tire to electric trains, metropolitan trains, monorail trains, new transport systems or other vehicles.

 In this type of tire, tires have hitherto been known as shown in FIG. 1 appended to the present application, the upper half of which represents a part of a tread structure and the lower half of which represents a part of '' a tire cut across its width.

 In the lower half of FIG. 1, the reference 51 designates a carcass comprising at least one ply and the reference 52 designates a belt superimposed around a top part or forming the crown of the carcass 51.

The belt 52 consists of three layers 53, 54 and 55 each containing cables, such as for example steel cables. The steel cords of each of the belt layers extend in a direction intersecting the equatorial plane XX of the tire, as shown in the upper half of FIG. 1,
In addition, the reference 56 designates a portion forming a tread. This tread portion 56 umgu * e five ribs 58 and 59 defined by four main circumferential grooves 57 extending in a zig-zag in the circumferential direction. In addition, each of the ribs 58 situated at the level of the portions forming the shoulders of the tire comprises several notches 60 arranged at substantially identical intervals in the circumferential direction of the tire.

 In this case, e2zlLE eraaLUe 60 is ql'cn called a blind notch, the two ends of which end in the rib located at the shoulder. In addition, the central part of the notch 60 in the direction of the width of the tire extends in the same direction as that of the cords 53a of the outermost layer 53 of the belt, relative to the equatorial plane XX of the tire.

 When the tire of this type is usually used under a high internal pressure of 9-12.105 Pa, the notch 60 tends to widen in the direction of the extent in width. In addition, the cords 53a of the outermost layer 53 of the belt are subjected to an intense tensile force in the state of acceleration, to a compression force in the state of contact with the ground and to a traction force at start-up during rotation of the laden tire. Consequently, when the central parts of the notch 60 are opposite the direction of the cable S3a to the outermost layer 53 of the belt relative to the layer la outermost 53 of the belt with respect to the equatorial plane XX of the tire, as shown in FIG. 1, an outer end part of the notch 60, in the direction of the width of the tire, which has the deformation the highest, deforms in particular in the direction of a greater increase in the width of the notch each time a tensile force is applied to the cable 53a, so that there is posed a problem consisting in that it s e produces a crack directed towards the surface of the rib situated at the level of the shoulder, due to a concentration of stresses or to what is called a tear at the level of the notch, and this starting from the zone of outer end of the notch 60, in the direction of the width of the tire.

 In addition, if the notch 60 opens towards the lateral end face of the tread portion 56, there is a problem that there appears another type of tearing at ltentaille, this tearing extending from the bottom of the notch 60 at the open end of the latter in the direction of the side wall.

 Furthermore, in order to sufficiently increase the rigidity of the tread portion 56 in order to improve the wear resistance and the traction performance in the conventional tire, the belt 52 is made up of three layers of cords in steel 53, 54 and 55, each of which is coated continuously from one side end to the other in the direction of width across the tire. Consequently, when driving the vehicle equipped with such tires by the action of a pilot wheel in contact with a side wall of a track, a guide plate or the like, an unnecessary intense force when cornering is created in the tire rotating under load, which causes the transmission of '' an intense force from the road surface to the surface of the tire in contact with the ground, which has the effect that the surface of the tire in contact with the ground may be subjected to uneven wear at the level of the part d 'ex lateral end of the tread, due to the pulling resistance effect.There may therefore be a problem that non-uniform wear progresses prematurely towards the center of the tread portion of rolling, in the direction of the breadth in width.

 In addition, in such conventional tires, the thickness of the rubber situated between the adjacent layers 53 and 54 of the belt, the cords of which extend in directions corresponding to opposite angles relative to the equatorial plane of the tire, is generally chosen. relatively thin and uniform across the full width of the belt layer. When the tire is deformed during its rotation under load, the rubber located in the lateral end parts of the layers 53, 54 of the belt and in the vicinity of these end parts is subjected to a strong shear deformation on the basis of the difference between the deformation behaviors of the adjacent layers 53 and 54 of the belt, and can be damaged as a result of its perforation by the ends of the cords of the lateral end parts of the belt. As a result, there may be a high risk of cracks appearing in damaged rubber and therefore separation between the belt layers and other serious problems, in a relatively premature manner.

 Therefore, an object of the present invention is to solve the above-mentioned problems of conventional tires and to provide a tire with a high-performance radial carcass, inflated to a high internal pressure and capable of effectively preventing the appearance of a tearing at the notches.

 Another object of the present invention is to provide a tire with a high-performance radial carcass inflated to a high internal pressure and in which advantageously the appearance of non-uniform wear can be limited by means of a sufficient reduction in force. when cornering and which makes it possible to effectively prevent the appearance of a tearing at the level of the notches and the growth of marginal wear at the level of the side end portion of the tread, disposed inwards, in the extension in width of the tire, which was not completely avoided in conventional tires.

 Another object of the present invention is to provide a high performance radial tire inflated to a high internal pressure, which can further delay the appearance of cracks in the rubber at the side end portions of the protective layer. the belt in the vicinity of its parts.

 In accordance with the present invention, a tire with a high-performance radial carcass is provided, inflated to a high internal pressure and comprising a carcass constituted by at least one ply, a belt constituted by a plurality of layers, the cords of which extend in a direction intersecting the equatorial plane of the tire, a portion forming a road strip and a cut notch disposed in each shoulder of the portion forming a tread, at given intervals, in the circumferential direction of the tire, characterized in that that at least one end portion of each of said cuts located in the vicinity of an edge the outermost layer of the belt extends in the same direction as that in which the cables of said most layer extend outside of the belt, relative to the equatorial plane of the tire.

 In a preferred embodiment, the belt consists of three layers of steel cords, that the innermost layer of steel cords of said belt has a subdivided structure such that a central part of this layer of steel cords is deleted in the width of the tire, that the middle layer of steel cords has a width greater than the innermost and outer layers of steel cords, that the width of said middle layer of steel cords is equal to 80- 110% of the width of the tread and that the width of each of said innermost and outermost layers of steel cords is in a range of 80-98% of the width of said middle strip of steel cords, while that the width of the removed portion of said innermost layer of steel cord lies in a range of 15- 50 8 of the width of said middle layer of c steel wheats.

 In another preferred embodiment of the invention, when the belt is formed by three layers of steel cords as mentioned above, a fine groove is further formed in said tread portion in a direction ciroor.rerentlel- ie so as to extend externally from a lateral edge of said outermost layer of steel cable, at a distance not greater than 15 mm in the erection of the width across the tire.

 In the other preferred embodiment of the invention, the thickness of the rubber between the adjacent layers of the belt, the cords of which cross while being inclined relative to the equatorial plane of the tire, is chosen to be 2 to 5 times greater in an end part of the belt layer than in a central part of this layer, in the direction of the width across the tire.

Other characteristics and advantages of the present invention will emerge from the description given below taken with reference to the appended drawings, in which:
- Figure 1 shows a schematic view of the tire with a conventional radial carcass;
- Figure 2 shows a schematic view of a first embodiment of the radial carcass tire according to the invention;
- Figure 3 shows a schematic view of a second embodiment of the radial carcass tire according to the invention;
- Figure 4 shows a schematic view of a third embodiment of the tire with radial breakage car according to the invention;
- Figure 5 shows a schematic view of a fourth embodiment of the radial carcass tire according to the invention; and
- Figure 6 shows a schematic sectional view of a fifth embodiment of the radial carcass tire according to the invention.

 In the tire with a high-performance radial carcass inflated to a high internal pressure, according to the invention, several notches are made in each of the ribs forming the shoulders, at given intervals, in the circumferential direction of the tire, at least a portion end of each of the notches located in the shoulder in the vicinity of the lateral end of the outermost layer of the belt extending in the same direction as that of the cords of the outermost layer of the belt, by relative to the equatorial plane of the tire, therefore, given that the direction in which the end portion of the notch extends, is identical to the direction of the outermost layer of the belt relative to the equatorial plane , when a force acting in the direction of a traction is applied to the cords of the belt, the end part of the notch is subjected deformation in one direction which reduces the width of the notch which has the effect that the stress concentration at the end of the notch can be sufficiently reduced, and makes it possible to sufficiently prevent the appearance of '' a tear at the level of the notch from the end of the latter.This is true, that the end of the notch ends in the rib of the shoulder or opens into the lateral end face of the tread portion.

 In addition, the expression "direction in which the end portion of the notch extends" is intended to include both a direction corresponding to a zero angle relative to the equatorial plane of the tire and a direction corresponding to a zero angle with respect to a meridian plane of the tire. In fact, even if the end portion of the notch makes a zero angle with respect to the equatorial plane or a meridian plane, the occurrence of a tear in the notch can be effectively prevented compared to the conventional technique, in which the direction, in which the end portion of the cut extends, is opposite to the direction of the cords of the outermost layer of the belt, with respect to the equatorial plane.

 When the belt is made up of three layers of steel cable, the innermost layer of steel cable, which acts to regulate the extension of the tire in the radial direction, has a subdivided structure, so that the role of the belt itself can be sufficiently developed and the turning force can be advantageously reduced without this reducing the rigidity at the side end portion of the tread t or the durability of the belt, which effectively prevents the occurrence of non-uniform wear due to the application of an intense force by the road surface to the part of the tire which is in contact with the ground. If the belt layer, other than the innermost layer of steel cords, has a subdivided structure, it is impossible to obtain a uniform shape for the crown or crown of the tire during inflation of the tire to an internal pressure. given.

 The reason why the width of the middle layer of steel cords is chosen to be greater than that of the other layers of steel cords and is in a range of 80-110% of the width of the tread, is bmee sur the fact that the re ennnn BE ~; 'å the lateral end of the tread spoke is sufficiently reinforced to advantageously improve the wear resistance of the lateral end part and that also the increase from the end portion of the middle layer of steel cords in a radial direction is effectively removed. In addition, the reason why the width of each of the innermost and outer layers of steel cords lies in a range of 80-98% of the width of the middle layer of steel cords is that, when this width is less than 80%, the stiffness of the side end portion of the tread and the durability of the belt ure cannot be increased sufficiently, while, when this value exceeds 98%, there occurs an early appearance of cracks in the rubber from the end of the belt layer and that the growth of cracks develops quickly.

 In beams, the reason why the width of the part removed from the innermost layer of steel cords lies in a range of 15-50% of the width of the layer mMirs ae cables en ant is because, when this width is less than 15%, an effective reduction in the cornering force cannot be obtained, while when this value exceeds 50%, the rigidity at the two lateral end portions of the tread in the width direction becomes too small.

 In addition, when the fine groove, which extends in the circumferential direction of the tire, is disposed in each lateral end portion of the tread, the progression of the marginal wear, which occurs at the portion lateral end of the tread, inwardly, across the width of the tire, can be effectively prevented, for example, when the thin groove is arranged in each of the ribs of the shoulders , defined by main circumferential grooves, part of the rib of the shoulder, situated outside the fine groove in the direction of the width of the tire, is opposed to the action of a lateral force does not cause wear of the edge, while a part of the rib of the shoulder situated inwards from the fine groove in the direction of the width of the tire only slightly supports the action of 'a lateral force and that the progression of the edge wear mentioned above is prevented by the presence of the fine groove, so that it appears uniform wear, without the appearance of edge wear.

 On the other hand, the reason why the position of the fine groove disposed in the tread portion is located 15 mm from the lateral edge of the outermost layer, which is the direction of the direction of the widthwise spread. pneumatic and de-al S @; t we, irsNe the fine is located externally at more than 15 mm in the direction of spread in width of the tire, the application of the lateral force at the edge of the part forming rib, located towards inside with respect to the thin groove in the direction of the width of the tire increases, while, when the thin groove is located more than 15 mm inwards in the direction of the width of the tire , the width of the edge wear at the level of the part of the rib situated outside the fine groove in the direction of the width of the tire is greater.

 In addition, in order to prevent the appearance of cracks from the bottom of the thin groove towards the lateral edge of the belt layer, it is appropriate to arrange the fine groove internally with respect to the lateral edge of the layer of the belt, in the direction of the width of the tire.

 Preferably, when the width of the fine groove is greater than 2 mm in the inflated state under the effect of the application of internal pressure, the opposite walls of the fine groove are in reciprocal contact when the tire is rolling under load, which prevents the appearance of a crack-like wear from the two marginal parts of the fine groove. In addition, when the depth of the fine groove is in a range of 50-110% of the depth of the main circumferential groove and is for example in a range of 530 mm, the progression of wear from the edge towards the The interior in the direction of the tire width extension is sufficiently prevented and also the appearance of cracks from the bottom of the fine groove is sufficiently prevented.

 In addition, when the thickness of the rubber between the cords of the adjacent layers of the belt, which intersect with respect to the equatorial plane, is given a value 2 to 5 times greater in the outer end part of the belt layer in the widthwise direction of the latter, than in the central part of the belt layer in the widthwise direction of this layer, the degree of deformation of the rubber appearing at the outer part of the belt layer or in its vicinity and producing the maximum deformation in this layer of the belt by shearing, can be considerably reduced compared to breaking the conventional technique when the tire is inflated and turns snx oER. , the quantity of rubber perforated by the ends of the cables at the lateral edge of the belt layer is sufficiently reduced and the instant of appearance ition of a crack in the rubber can be largely delayed.

 The reason why the thickness of the rubber between the adjacent layers of the belt is chosen 2 to 5 times greater at the level of the outer end part of the belt layer than at the central part of this layer in the direction of spread in width of the tire is due to the fact that, when aLS epusnr er is less than å2 SEs the thickness located at the level of the central part of the layer of the belt, the appearance of cracks in the rubber at the level of the end part of the belt and in its vicinity cannot be delayed, while, when this coefficient exceeds 5, the appearance of cracks cannot be effectively delayed and, on the contrary, a thermal rupture of the rubber is caused by the heat accumulated therein.

 According to the invention, it is preferable that the tensile modulus at 100% of the rubber located inside the layer of the belt and between the layers of the latter is equal to 5-9.106 Pa. In this case, the shear deformation of the rubber between adjacent layers of the belt can be further reduced, which delays the appearance of cracks in the rubber, and also the increase in the circumferential length of the tire can be advantageously reduced during inflation of the tire. pneumatic.

When the tensile modulus at 100% is less than 5,100 Pa, the shear deformation becomes too great whereas, when this value exceeds 9,106 Pa, the stiffness of the rubber becomes too high, which leads to a reduction in the resistance of the rubber to cracks.

 In addition, it is advantageous that the angle of the cords in the layers of the belt, which extend in mutually opposite directions r is included in a range of 10030 relative to the equatorial plane of the tire. Consequently, the increase in the circumferential length of the tire can be sufficiently safe during inflation of the tire and during rotation under load.

 When the angle of the cords with respect to the equatorial plane of the tire is less than 10, the shear deformation at the end portion of the cord, in the width direction, of the layers of the belt, which cross in opposite directions, increases by prematurely showing a crack in the rubber in the end part, in the width direction, of the belt layer, while when this angle exceeds 30 ", the extension of the belt layer in the radial direction becomes important during inflation with high internal pressure and also the shear deformation in the end part1 in the width direction, crossed layers of the belt increases causing the appearance premature cracks in the rubber in the end portion, crosswise, of the belt layer.

 FIG. 2 shows a first embodiment of a tire with a high-performance radial carcass according to the invention, in which the reference l designates a carcass, the reference 2 a belt superimposed around a part forming crown of the carcass 1, and the reference 3 a part forming a tread and constituting the part of the tire, which comes into contact with the ground.

 The carcass 1 is constituted by at least one ply containing cords arranged substantially in the radial direction of the tire, while the belt 2 is constituted by a plurality of layers, the cords of which cross with respect to the equatorial plane X-X of the tire. In this embodiment, the belt 2 is formed by three layers 4,5 and 6.

 In the tread portion 3, five ribs 8 and 9 extending in the circumferential direction of the tire are defined by four main circumferential grooves 7. At least some of these ribs 8 located at the shoulders (only the ribs corresponding to the shoulders in this embodiment) comprise several notches or slots 10 substantiallyiisis, drs the circumferential diccdcn W paI = t $ pe.

 As seen in the upper half of Figure 2, each of these notches 10 is a blind notch, the ends of which terminate in the rib of the shoulder. In addition, each notch 10 extends in the same direction as that in which the cables II of the outermost layer 4 of the belt extend, relative to the equatorial plane XX of the tire, over the entire length of the notch. Consequently, the outer end part of the notch 10 in the direction of the width of the tire has the maximum degree of deformation, or else the end part situated in the vicinity of the lateral edge of the outermost layer 4 of the belt, in the direction of the width of the tire, is also rientée in the same direction as that in which the cord II of the outermost layer 4 extends.

 The characteristic, according to which the direction of the notch 10 is the same as that in which the cables extend from the outermost layer 4 of the belt relative to the equatorial plane XX, means that the notch 10 extends in the same quadrant as the cables II when orthogonal coordinates are defined by a straight line parallel to the equatorial plane XX and to the southern plane of the tire, in a correct position in the notch and in a correct position on the cable. In this case, the direction in which the notch 10 extends, may coincide with the uncoordinated axis.

 In the embodiment shown, one end of the notch 10 can open so as to open either in the wall of the circumferential main groove 7, or in the lateral end face of the tread portion 3, or both in the wall of the groove and in the lateral end face of the tread portion.

 In accordance with the tire of the embodiment shown, even when an intense tensile force is applied ax dFk 11 of the outermost layer 4 of the belt, during acceleration or starting states, during rotation s1s, this has the effect that the deformation, which reduces the width of the notch 10 at the outer end portion of this notch in the direction of the width across the tire has its maximum intensity, which prevents effectively the appearance of cracks from the outer end of the notches towards the surface of the rib of the shoulder. This is particularly effective when the direction, in which the notch 10 extends, coincides with the direction, in which the cables 11 are drawn, in the orthogonal coordinates mentioned above.

 Similarly, such deformation behavior at the outer end portion of the notch manifests when an end of 11 notch 10 opens into the side end face of the tread portion 3. C that is to say that the tensile force acting on the cable does not increase the width of the notch 10, but causes a deformation reducing the width of the notch, which effectively prevents the appearance of cracks in direction of the lateral end face of the tread portion.

 Therefore, according to the tire shown, the tear in the notch produced from the end of this notch 10 which is subjected to the highest degree of deformation can be effectively prevented.

 FIG. 3 shows a second embodiment of the tire with a high-performance radial carcass according to the invention, which is a modified embodiment of FIG. 2. That is to say that only the part of curved outer end of each of the notches 10, located in the rib 8 of the shoulder which is located in the vicinity of the lateral end of the outermost layer 4 of the belt, extends in the same direction as that in which the cables 11 of the outermost layer 4 of the belt extend, with respect to the equatorial plane XX, as shown by the orthogonal coordinates in FIG. 3.

In the embodiment of FIG. 3, the part of the notch 10 in which the degree of deformation is greatest, or else the part, in which a tear is likely to appear at the level of
The notch is directed in the same direction as that in which the cables 11 extend, so that such a notch end part is deformed in the direction of reducing the width of the notch as in the case of Figure 2, and therefore this prevents caceration the appearance of a tear from the end of the notch. In addition, the same applies when the end of the notch opens into ls. lateral end face of the tread portion.

 When the notch is bent with a wide bend as shown in Figure 3, it is advantageous that the radius of curvature of the bent part of the notch is chosen as large as possible in order to prevent the appearance of a tear from the elbow of the cut.

 even in the embodiment of Figure 3, the occurrence of a tear from the notch can be sufficiently prevented.

 FIG. 4 shows a third embodiment of the tire with a high-performance radial carcass, in accordance with the invention, which is an alternative embodiment of FIG. 2.

 Darus this famé ce la n,> belt 2 is omstiti pr t = s alp 4,5 and 6 of steel cables, which cross by being inclined compared to the equatorial plane X-X. Among these layers of steel cords, the innermost layer of steel cords 6 has a subdivided structure such that the central part of the layer is eliminated in the direction of the widthwise spread of the tire, which reduces the force in bend of the tire. The width W1 of the middle layer of steel cords 5 is chosen to be greater than the widths of the other layers of steel cords 4.6 and is in a range equal to 80-110% of the width W of the strip. of rolling, which sufficiently increases the rigidity at the lateral end portion of the tread 3 and sufficiently prevents the detachment at the end portion of the layer of steel cords 5, relative The width W2 of both the innermost layer of steel cord 6 and the outermost layer of steel cord 4 is in a range equal to 80-98% of the width W1 of the layer. e median of steel cords 5, which sufficiently increases the rigidity at the lateral end portion of the tread and the durability of the belt and also makes it possible to delay the instant of appearance of cracks from the end of the belt layer, which slows the growth rate of cracks.

 In addition, the width W3 of the central part removed from the innermost layer of steel cords 6 corresponds to a range of 15-50% of the width W1 of the middle layer of steel cords 5, which prevents reduction extreme rigidity in the central part of the tread 3 in the direction of the width of the tire, and also results in an effective reduction of the force when cornering.

 In the belt 2 of FIG. 3, the angle of the cables of each of the layers of steel cables 4,5 and 5 with respect to the equatorial plane XX is equal to 45'-80 'upwards and to the right in the innermost layer, at l0 -30 up and to the right in the middle layer and 10 "-30" up and to the left in the outermost layer. Ehvari, the directions of the cables in the layer the innermost and middle layer may extend upward and to the left and the direction of the outermost layer cords may extend upward and to the right.

 In the embodiment shown, several notches 10 are formed with the same pitch in each of the five ribs 8, 9 defined by the four main circumferential grooves 7, which have a depth of 5-30 mm. In addition, these notches can be arranged with unequal steps or can be formed only in the ribs of the shoulders.

 In the tire shown, these notches 10, which have a width of not more than 1 mm and a depth corresponding to 10-110% of the depth of the main groove, are formed by being distributed with an identical pitch equal for example to 5- 40 mm in the circumferential direction of the tire. As shown in FIG. 4, the notch 10 is an open notch, the two ends of which open into lateral faces of the ribs 8, 9. In addition, the notch 10 can be a notch at least one end of which ends in the rib.

 The whole of the notch 10 extends in the same direction as that in which the cables 11 of the outermost layer of steel cables 4 extend relative to the equatorial plane XX, as in FIGS. 2 and 3 The angle of inclination of the notch 10 relative to the equatorial plane XX is preferably within a range of 40 "-90 '. That is to say that the notch, which has an angle of tilting of 904, contributes in a very effective way to improve the resistance to wear, while, when the tilting angle is less than 40D, the opposite side walls of the notch come into constant mutual contact during the rotation of the tire sxs drç, and the function of the notch itself cannot substantially develop. The appearance of a tear in the notch can be effectively prevented due to the presence of such notches, in the same way as in the embodiments previously mentioned.

 In accordance with the tire of FIG. 4, the cornering force not necessary for this type of tire can be effectively reduced without being at the expense of the rigidity at the level of the lateral end portion of the tread, or at the expense of the durability of the belt 2, which makes it possible to increase to a large extent the wear resistance and in particular the resistance to non-uniform wear of the tire.

 FIG. 5 shows a fourth embodiment of the tire with a high-performance radial carcass according to the invention. This tire is a modified embodiment of FIG. 4, in which the tread portion 3 is subdivided by two main circumferential grooves 7 having a depth of 5-30 mm into three ribs 8.9, and a fine groove 12 , which extends directly in the circumferential direction of the tire, is formed in each of the ribs 8 of the shoulders, in a position located less than 15 mm from the lateral end of the outermost layer of steel cords 4, years the turkey of the width in width of the pnelmatique.In addition, the thin groove 12 can extend in a zig-zag in the circumferential direction. given internal pressure, a depth corresponding to 5070% of the depth of the main circumferential groove.

 In this embodiment, the progression of the edge wear produced at the lateral end portion of the tread, inwardly in the direction of the width across the tire, can be prevented d '' a substantially total way thanks to the effect produced by the fine groove 12. In addition, since the width of the fine groove 12 is not more than 2 mm for a given internal pressure, the appearance of a lateral wear from the two edge portions of the thin groove can be prevented. In addition, the reason why the depth of the thin groove is limited to 50-110% of the depth of the main circumferential groove is due to the fact that , mspe cedt depth is not less than 50%, this does not allow the application of the same force when cornering, as in the case of the absence of a fine groove, to the part of the rib located internally by in relation to the throat, in the direction of stretched width of the tire, while when the depth is greater than 110% of the depth of the main circumferential groove, the occurrence of cracks at the bottom of the groove is prevented.

 FIG. 6 shows a fifth embodiment of the tire with a high-performance radial carcass according to the invention, which is a modified embodiment of FIG. 2. In this case, the belt 2 consists of two layers 4,5, the cords of which cross with respect to the equatorial plane XX. In addition, the belt can be formed by several layers. The angle of inclination of the cables in these layers 4.5 of the belt with respect to the equatorial plane XX is equal to lG4-30 upwards and to the left in the outer layer 4 and to lO -30 upwards and to the right in the inner layer 5.

 In addition, the rubber coating for these layers of the belt and the rubber arranged between these layers preferably have a tensile modulus at 100% equal to 5-9.106 Pa, which makes it possible to obtain a sufficient reduction in deformation by rubber shear between the layers of the belt. On the other hand, the tread portion 3 can advantageously be made of a rubber containing not less than 15% natural rubber, which makes it possible to prevent the reduction of the notching resistance and of the resistance to chip formation. Such rubbers are naturally applicable to all the embodiments mentioned above.

 In the embodiment of Figure 6, when the width of the layer 4 of the belt is less than that of the layer 5 of the belt, as shown in Figure 6, the thickness between the cross cords of the adjacent layers 4 and 5 of the belt - relative to the equatorial plane XX is chosen 2 to 5 times greater at a position E of the lateral edge of the layer 4 of the belt, which has a reduced width, than the thickness T has in a central part C of the belt layer, in the direction of the width of the tire. In addition, the expression "thickness of the rubber between the layers of the belt", used here, denotes a distance between the inner edge of the cord of the outer layer 4 of the belt in the radial direction of the tire and the outer edge of the cord of the inner layer 5 of the belt, in the radial direction of the tire.

In addition, the tread portion 3 is subdivided by two main circumferential grooves 7 into three ribs 8, 9, in the same manner as in the case of FIG. 5. Each of these ribs, in particular the ribs 8 of the shoulders, comprises several notches 10 (not shown) and may comprise, if necessary, a plurality of lateral grooves
In accordance with the tire of FIG. 6, the effect of the ribbon located in the vicinity of each of the layers 4.5 of the belt by the other layer of this belt is made sufficiently weak, in the deformation of the tire during the rotation of the latter. under load, which has the effect that the shear deformation of the rubber located at the lateral end portions of the layers 4.5 of the belt and in the vicinity of the latter can be greatly reduced compared to the conventional technique. Consequently, the perforation of the rubber by the ends of cords at the lateral edges of the layers 4.5 of the belt can be reduced enough to effectively delay the moment of appearance of cracks in the rubber.

 Apart from the embodiments mentioned above, the invention is applicable to smooth tires. In addition, a block structure, a bridge structure, or a combination of two or more types of structures can be used as the tread structure, in addition to the rib structure.

 The examples given below are given by way of illustration of the invention and are not intended to constitute limitations thereof.

Example 1
The state of appearance of a tear at the level of a notch was studied, in conjunction with the following three test tires having the dimensions TBR Ex3.50 / 85 R16.

 The first dressai tire was a tire having a tread structure shown in Figure 2 (the direction in which the outer end portion of the cut extends extends at an angle of 70 "from the equatorial plane ) and the second test tire was a tire having a tread structure shown in FIG. 3 (the direction, in which the outer end part of the notch extends, makes an angle of 50 relative to in the equatorial plane) and the third test tire was a tire having a tread structure shown in FIG. 1 (the direction, in which the outer end part of the notch extends, makes an angle of 1300 compared to the equatorial plane).

Each of these test tires had the following dimensions:
Outermost layer of the belt: width 190 mm,
cable angle 70 "up and to the right
in relation to the equatorial plane,
Belt middle layer: width 210 mm, angle of
wired 20 up and to the right relative
at the equatorial plane,
Outermost layer of the belt: width 185 mm,
wired angle 20 up and to the left
in relation to the equatorial plane,
Tread width: 216 mmt
Main circumferential groove: Depth 8 mm, maximum width 18 mm, minimum, width 12 mm.

Distance between the bottom of the main circumferential groove and the belt: 5 mm
Inner pressure: ll, 7.5 05 Pa.

 Each of these test tires was mounted on a driving wheel of a metropolitan vehicle and actually covered a distance of more than 100,000 km. Then, vElem = t was examined for the appearance of a tearing at the notches and the results indicated in Table 1 below were obtained.

Table 1
Pneumatic Pneumatic Pneumatic
of fig. 2 of fig. 3 of fig. 1
Appearance state
numerous appearance
of a de- no appa no torn appa
rition rure rure
size level of
notches 5 mm in ni
calf
sizes
As can be seen from Table 1, the tires according to the invention make it possible to considerably reduce the appearance of the tear in the notches, compared with the case of the conventional tire.

Example 2
The resistance to wear was measured, the resistance to wear n: n'znimrnaet the state of appearance of a tear in the notches, in relation to the following two test tires, having dimensions
E13.50 / 85 R16.

Tire according to the invention
It was a tire with a structure
tread shown in FIG. 4,
in which the angle of the most layer cables
inner belt relative to the equato plane
rial was 65 "up and to the right,
the angle of the cables of the middle layer of the belt
was 200 up and to the right,
the angle of the cables of the outermost layer of
the belt was 200 up and down
left, the width of the part removed from the layer
the innermost part of the belt corresponded to 30%
the width of the middle layer of the belt, and
the notch was tilted at an angle of 70 "to the
up and to the left in relation to the equatorial plane
and had a width of not more than 1 mm and a
8.2 mm depth, the interval between the notches
was equal to 15 mm in the circumferential direction
tire, and throat depth
main circumference was 9.7 mm.

Classic pneumatics
It was a tire with a structure
tread shown in FIG. 1,
in which the angle of each end part of
the notch relative to the equatorial plane was equal to
70, and the other structures were the same as
in the tire according to the invention.

 Each of these test tires was mounted on a rim 9, q0 V x 16 on the driving axle of the metropolitan vehicle and was rolled, with an internal inflation pressure at 9.8.105 Pa, over a distance 100,000 km on one track. Then, the state of appearance of a tear at the notches was visually examined and the resistance to wear was evaluated by measuring the degree of wear from the remaining amount of the main circumferential groove, and resistance to non-uniform wear was evaluated by measuring the difference in the degrees of wear between the central rib and the rib of a shoulder.

 The measured results are reproduced in Table 2 according to n, in addition, the resistance to wear and the resistance to non-uniform wear is represented by an indexz whose value 100 corresponds to conventional tires. The higher the value of the index, the better the characteristic.

Table 2
Performances of the Pneumatics
classic tire me to the invention
Resistance to
wear 100 130
Resistance to
wear not
uniform 100 300
State of appearance - Name appearance
tion of a tear none
tear from a length of Apparition
hack shot - 5 mm from
the cuts
As can be seen in table 2, all the performances of the tire according to the invention are excellent compared to the conventional tire.

Example 3
The state of appearance of non-uniform wear was measured in connection with the following three test tires having the dimensions E315 / 75 R22.5.

Tire according to the invention
It was a tire with a structure
tread shown in FIG. 5,
in which the angle of the most layer cables
inner belt relative to the equato plane
rial was 65 "up and to the right,
the angle of the cables of the middle layer of the belt
was 20 up and to the right,
the angle of the cables of the outermost layer of
the belt was 20 up and down
left, the width of the part removed from the layer
the innermost of the belt was 30%
the width of the middle layer of the belt and
the thin groove was formed in the part of the band
bearing, in a position located externally
2 mm from the lateral edge of the outermost layer
from the belt, in the direction of the extension in lar
tire, and had a throat of a lar
gor of 1 mm for a given internal pressure and, a
depth corresponding to 90% of the depth of the
main circumferential throat.

Comparative pneumatics I
It had the same construction as the tire
according to the invention, except that it did not include
the throat.

Comparative pneumatics Il
It had the same construction as the tire
in accordance with the invention, except that the most
inner belt did not have a struc
ture subdivided.

 Each of these test tires was mounted on a 9.00 x 29.5 rim on the driving axle of the metropolitan vehicle and traveled a distance of more than 100,000 km while being inflated with an internal pressure of 9 x 105 Pa. Next, the state of appearance of non-uniform wear was visually examined and the results shown in Table 3 below were obtained.

Table 3
Pneumatic Pneumatic Pneumatic
next Comparative Comparative
invention I II
Appearance condition The wear of the edge The wear of The wear of the
rition of one appeared in edge of edge is ap
wear not part of the rib appeared at the ni
uniform killed outside the shoulder- calf of the
laughter is gone if-
no throat in appeared killed outside
the direction of on all laughingly
the extent in width with respect
width of this at the fine
pneumatic, grooved rib in
while- management
no wear of the extent
edge is not in width
appeared in one of the pneumati
part located that and has
internally progressed
compared to up to one
the throat, part if
so killed inté
the tire laughing
was worn uni- compared
formally in fine
his outfit. throat.

 As can be seen from table 3, in accordance with the tire according to the invention, the innermost layer of the belt has a subdivided structure and the fine groove, which extends in the circumferential direction, is located in the region data of the shoulder part so that the progression of the wear of the edge, produced in the end-lateral part of the tread, internally in the direction of the width spread of the tire, can be prevented d 'a very effective way.

Example 4
The appearance of cracks in the rubber was measured from the end portions of the adjacent layers of the belt, the cords of which cross with respect to the equatorial plane of the tire, using the following three test tires having dimensions El3.50 / 85 Ri6.

Tire according to the invention
It was a tire with the structure
shown in Figure 6, in which the angle of
wired from each of the adjacent layers of the belt
ture in relation to the equatorial plane of the tire
was 20, and the rubber in each layer
of the belt and between these layers had a mo
dule in tension at 100% equal to 7.106 Pa and
the thickness of the rubber between the adjacent layers
of the belt in the lateral end part of
the latter was 3 times greater than that (1 mm)
of the central part.

Comparative pneumatics
It had the same structure as the tire
according to the invention, except that the thickness of the
rubber in the end side part was
5.5 times greater than that (l mm) of the cen part
trale.

Classic pneumatics
The thickness of the rubber in the end part
lateral was 1.5 times that (l mm) of
the central part
Each of these tires was mounted on a 9.00 V x 16 rim and was rolled over a distance of more than 100,000 km on a drum test machine, with inflation at an internal pressure of 11, 7.105 Pa. Next, the state of appearance of cracks in the rubber was examined from the end portion of the belt layer and the results indicated in Table 4-following were obtained.

Table 4
Pneumatic Pneumatic Pneumatic com
comparative comparative comparative conform
to the invention
State of ap- Cracks Cracks- The appearance of
appearance of an ion- ers of a cracks was
of non-length cracker observed in
lower res not inf- parts of neck
at 10 mm are higher than adjacent
appeared at 10 mm from the waist,
from appeared to but their lon
parties from gueur was
very weak end parts.

end layers
adjacent neck tee
from the belts adja
ture centes of
the belt, while
that the
rubber
situated in
the part
end
cracked
presented
a shape
a break
thermal
As previously mentioned, in accordance with the invention, the part of the notch, in which the degree of deformation is highest, extends in particular in the same direction as that in which the cables of the outermost layer of the belt with respect to the equatorial plane of the tire, so that the appearance of a tear from the notches can be greatly reduced.In addition, the wear resistance and the resistance to non-wear uniformity can be greatly improved when using the subdivided structure for the innermost layer of the belt from among the plurality of belt layers. Furthermore, the progression of wear at the edge, which is produced on the lateral end portion of the tread, internally in the circumferential direction of the tire, can be sufficiently hindered to prolong the life of the tire. thanks to the arrangement of the fine groove in the rib of the shoulder, in a given position. In addition1 the thickness of the rubber present between the layers of the belt is given a higher value in the lateral end portion of the belt layer than in its central portion1 which makes it possible to remove in a way effective the appearance of cracks in the rubber from the outer lateral end of the belt layer and significantly improves the durability of the tire.

Claims (6)

 1. Tire with radial carcass of high performance, inflated to a high internal pressure and comprising a carcass (1) constituted by at least one ply, a belt (2) constituted by a plurality of layers (4,5,6), the cords of which extend in a direction intersecting the equatorial plane of the tire, a tread portion (3r and a plurality of notches (10) disposed in each shoulder of the tread portion, at given intervals, in the circumferential direction of the tire, characterized in that at least one end portion of each of said notches (10) located in the vicinity of an edge the outermost layer (4) of the belt extends in the same direction, than that in which the cords extend from said outermost layer (4) of the belt, relative to the equatorial plane of the tire.  2. High performance radial carcass tire according to claim 1, characterized in that said belt (2) consists of three layers of steel cords (4,5,6), than the innermost layer of steel cords (6) of said belt (2) has a subdivided structure such that a central part of this layer of steel cords is removed across the width of the tire, that the middle layer of steel cords (5) has a width greater than the most inner and outer layers of steel cords (4,6), that the width of said middle layer of steel cords (5) is equal to 80-110% of the width of the tread (3 ) and that the width of each of said innermost and outermost layers of steel cords (4,6) is in a range of 80-98% of the width of said median strip of steel cords (5), while the width of the part removed from said most layer inner of steel cords (6) is in a range of 15-50% of the width of said middle layer of steel cords (5).  3. High performance radial carcass tire according to one of claims 1 or 2, characterized in that a fine groove (12) is further formed in said tread portion (3) in the circumferential direction so as to extending outwardly from a lateral edge of said outermost layer of steel cords (4), at a distance of not more than 15 mm in the direction of the width of the tire.  4. High performance radial carcass tire according to any one of claims 1 to 3, characterized in that the thickness of the rubber between the adjacent layers (4,5,6) of the belt (2), including the cords intersect by being inclined relative to the equatorial plane of the tire, is chosen 2 to 5 times greater in an outer end part of the belt layer than in a central part of this layer, in the direction of the width across the tire.  5. A high-performance radial carcass tire according to claim 1, in which the rubber located in said layer of the belt and between adjacent layers (4,5,6) of the latter has a tensile modulus at 100% equal to 5-9.106 Pa.  6. High performance radial carcass tire according to claim 3, characterized in that said fine groove (12) has a width of not more than 2 mm, with inflation by internal pressure, a depth corresponding to 50-110% of the depth of a circumferential main groove (7) extending in the circumferential direction of the tire.