Title of Invention

TYRE BREAKER PLY REINFORCEMENT

Abstract

The invention concerns a tyre with radial casing (1), a breaker ply reinforcement (3) comprising at least two working breaker plies (32, 34) made of inextensible elements crisscrossed from one ply to the other, while forming with the circumferential direction angles ranging between 10° and 45°, and an axially continuous additional ply (33) made of inextensible and substantially radial continuous metal steel reinforcing elements, said ply being radially placed between the working plies (32, 34), and having an axial width L33 not less than 1.1 times the axial width L32, L34 of the wider working breaker ply (32, 34).

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] COMPAGNIE GENERALE DES ESTABLISSEMENTS MICHELIN-MICHELIN 8s CIE, a French company., 12, Cours Sablon, F-6304"0 Clermond-Ferrand, Cedex 09, France The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- 15-6-2004 CROWN REINFORCEMENT FOR A TYRE The invention relates to a tyre with radial carcass reinforcement anchored in each bead to at least one bead wire, and comprising a crown reinforcement formed 5 by at least two so-called working plies, superposed and made of wires or cables which are parallel to each other in each ply and are crossed from one ply to the other, forming angles of at most 45° in absolute value with the circumferential direction of the tyre. 10 French Application FR 2 728 510 relates to a tyre as described above, and more particularly to a "heavy vehicle"-type tyre, the ratio of the height above rim H to the maximum axial width S of which is at most 0.60. Said application, in order to improve the life of the 15 crown reinforcement of such a tyre, and also the regularity of wear of the tread thereof, advocates an architecture of the crown reinforcement characterised by the combined presence in said reinforcement of an axially continuous ply of inextensible cables forming 20 an angle of at least 60° with the circumferential direction of the tyre, and a ply of metallic elements oriented substantially parallel to the circumferential direction, arranged radially between the two working crown plies. 25 The object of such an architecture is to reduce the operating temperatures at the edges of the working plies, the width of the additional ply of circumferential cables being less than the widths of the working plies. 30 Some current tyres, called "highway" tyres, are intended to travel at high speed and on longer and longer journeys, owing to the improvement in the road network and the growth of the motorway network ^—™— 2 throughout the world. All the conditions under which such a tyre is required to travel without doubt make it possible to increase the number of kilometres travelled, the wear of the tyre being less, but on the 5 other hand the endurance of the latter and in particular of the crown reinforcement is adversely affected. The lack of endurance relates both to the fatigue resistance of the crown plies, and in particular the resistance to separation between ends of 10 plies, and to the fatigue resistance of the cables of the portion of carcass reinforcement located beneath the crown reinforcement, the first deficiency being greatly influenced by the operating temperature at the edges of the working plies, whether travelling in a 15 straight line or under drift. The problems referred to above have been satisfactorily solved by specifying the methods of application of the principle of architecture described above. Thus French application FR 2 744 955 claims and describes a tyre 20 with radial carcass reinforcement, of an H/S form ratio of at least 0.60, and having a crown reinforcement comprising at least two working crown plies of inextensible cables, crossed from one ply to the other, forming angles of between 10° and 45° with the 25 circumferential direction, and, in the absence of any ply formed of inextensible cables forming an angle greater than 45° with the circumferential direction, an additional, axially continuous, ply formed of metallic elements oriented substantially parallel to the 30 circumferential direction, placed radially between the working plies, and the axial width of which is at least 1.05 times the axial width of the widest working crown ply, and preferably at least 1.1 times the width of said widest working crown ply. 3 Although the problems relating to the separation between working plies and the fatigue resistance of the carcass reinforcement cables would appear to be solved, if the operating temperatures are greatly reduced, 5 whatever the form ratio of the tyre, on the other hand prolonged travel under drift of the tyres thus constructed and having a form ratio of at most 0.60 causes fatigue failure of the cables of the additional ply, and more particularly of the edges of said ply to 10 occur, whether or not the so-called triangulation ply is present. The object of the invention is to obtain, for the tyre in question, the best possible compromise between the different qualities which the reinforcements of such a 15 tyre must possess, namely the fatigue resistance of all the reinforcement elements of the reinforcement plies, the resistance to separation between plies, as low as possible an operating temperature, and not forgetting the lowest possible weight of the tyre and industrial 20 cost price. The tyre according to the invention, having a radial carcass reinforcement, a crown reinforcement comprising at least two working crown plies of inextensible reinforcement elements, crossed from one ply to the 25 other ply, forming angles of between 10° and 45° with the circumferential direction, and an additional, axially continuous, ply formed of metallic reinforcement elements which is placed radially between the working plies, and the axial width of which is at 30 least 1.1 times the axial width of the widest working crown ply, is characterised in that the reinforcement elements of the additional ply are continuous, inextensible, substantially radial metallic elements. 4 The additional ply advantageously has a substantially zero meridian curvature, and is separated from the first and second working plies by the necessary profiled members, of substantially triangular shape. 5 "Substantially zero meridian curvature" of said ply is to be understood to mean a curvature, the radius of which is at least 2.00 times the equatorial radius of curvature of said ply. "Inextensible cable" is to be understood to mean a 10 cable, for instance a steel cable, which has a relative elongation of less than 0.5%, measured at 10% of its breaking load. Substantially radial metallic elements are elements which form angles within the range of +85°, -85° around 15 0° with the circumferential direction. The crown reinforcement according to the invention will advantageously be finished off by a so-called protective crown ply, formed of elastic metal cables made of steel, oriented relative to the circumferential 20 direction at an angle substantially equal to the angle formed by the cables of the radially outermost working crown ply, and the axial width of which is at least equal to the axial width of the radially outermost working ply. 25 Whatever the solution described above, the crown reinforcement may also be finished off, radially to the inside between the carcass reinforcement and the radially inner working ply closest to said carcass reinforcement, by a so-called triangulation ply of 30 inextensible reinforcement elements, forming with the circumferential direction an angle greater than 60° and of the same direction as that of the angle formed by the reinforcement elements of the ply radially closest 5 to the carcass reinforcement. Said triangulation ply may have an axial width less than said widest working ply, which, in the crown reinforcement in question, is radially closest to the carcass reinforcement. Said 5 triangulation ply may also advantageously have an axial width greater than the width of the widest working ply. The characteristics and advantages of the invention will be better understood with reference to the following description, which refers to the drawing, 10 illustrating in non-limitative manner an example of embodiment, and in which: - Figure 1 shows a diagram, viewed in meridian section, of a crown reinforcement according to the invention, 15 - Figure 2 shows a diagram of a second variant of a crown reinforcement according to the invention. The tyre P, of dimension 385/55.R.22.5 X, has an H/S form ratio of 0.55, H being the height of the tyre P on its mounting rim and S its maximum axial width. Said 20 tyre P comprises a radial carcass reinforcement (1) anchored in each bead to at least one bead wire, forming an upturn, and formed by a single ply of metal cables. This carcass reinforcement (1) is hooped by a crown reinforcement (3), formed radially from the 25 inside to the outside by a first working crown ply (32) formed of inextensible metal cables made of steel, oriented by an angle a, equal in the case illustrated to 18°, 30 - surmounting the first working crown ply (32), by an additional ply (33) formed of inextensible metallic elements made of steel, said elements being oriented at an angle of 90° relative to the circumferential direction, and the axially outer edges of the first working crown ply being 5 separated from the additional ply (33) of radial elements by profiled members (4) of substantially triangular cross-section, the thickness e2 of rubber between the ply (32) and the ply (33), measured at the axially outer end of the ply (32), 10 being substantially equal to 2 mm, then by a second working crown ply (34) formed of metal cables identical to those of the first ply (32) , and forming an angle /3, opposed to the angle a and, in the case illustrated, equal to said 15 angle a of 18° (but possibly being different from said angle a), with the circumferential direction, and finally by a final ply (35) of so-called elastic metal cables made of steel, oriented relative to the circumferential direction by an 20 angle y of the same direction as the angle /? and equal to said angle /3 (but possibly being different therefrom), this last ply being a so-called protective ply, and so-called elastic cables being cables having a relative elongation 25 of at least 4% upon rupture. The axial width l32 of the first working ply (32) is equal to 0.75 times the maximum axial width SQ of the centre section of the carcass reinforcement (1), namely 290 mm, which, for a tyre of conventional shape, is 30 very much less than the width of the tread, which is equal in the case in question to 325 mm. The axial width L34 of the second working ply (34) is substantially equal to the width l32 since it is 286 mm. The axial width L33 of the additional ply (33) 7 is equal to 320 mm, which represents 0.827 SQ. In actual fact, the width L33 of the additional ply (33) is very much greater than the width L32 (L34) of the widest working ply. The final crown ply (35), referred to as 5 a protective ply, has a width which is very slightly greater than the width L34 of the working crown ply (34), namely 300 mm. The secant modulus of extension of the working ply (32) or of the working ply (34), which are identical in the 10 present case, since they are formed of the same non-hooped 14.28 metal cables made of steel which are inextensible and continuous over the entire width of the ply, said cables being arranged with the same pitch, that is to say with the same space between 15 cables (measured perpendicular to said cables), is preferably greater than 5000 daN/mm2 at 0.4% relative elongation, and in the case in question equal to 5500 daN/mm2. As for the additional ply (33) , its secant modulus of compression for a relative 20 contraction of 0.4% is preferably between 0.33 and 0.66 times its modulus of extension for a relative elongation of the same size. In the case in question, the ply (33) is formed of hooped 27.23 metal cables made of steel. 25 The tyre illustrated in Figure 2 differs from the tyre of Figure 1 by the addition of a so-called triangulation ply (31), arranged radially to the inside between the carcass reinforcement (1) and the radially inner working ply (32) closest to said carcass 30 reinforcement (1). Said triangulation ply (31) is formed of inextensible metal cables made of steel, forming with the circumferential direction an angle S of 65° of the same direction as that of the angle a formed by the reinforcement elements of the working ply 35 (32) radially closest to the carcass reinforcement (1). WE CLAIM: 1. A tyre having a radial carcass reinforcement (1), a crown reinforcement (3) comprising: at least two working crown plies (32, 34) of inextensible reinforcement elements, crossed from one ply to the other ply, forming angles of between 10° and 45° with the circumferential direction, and an additional, axially continuous, ply (33) formed of metallic reinforcement elements which is placed radially between the working plies (32, 34), and the axial width L33 of which is at least 1.1 times the axial width L32, L34 of the widest working crown ply (32, 34), characterised in that the reinforcement elements of the additional ply (33) are continuous, inextensible, substantially radial metallic elements made of steel. 2. A tyre as claimed in Claim 1, wherein the additional ply (33) has a substantially zero meridian curvature. 3. A tyre as claimed in one of Claims 1 or 2, wherein the ply (33) is formed of hooped metal cables, its secant modulus of compression for a relative contraction of 0.4% being between 0.33 and 0.66 times its secant modulus of extension for a relative elongation of the same size. 4. A tyre as claimed in one of Claims 1 to 3, wherein the crown reinforcement (3) furthermore comprises a continuous so-called protective ply (35) radially located above the last working ply (34), formed of elastic metal cables, and the axial width L35 of which is at least equal to the axial width L34 of the radially outermost working ply. 5. A tyre as claimed in one of Claims 1 to 4, wherein the crown reinforcement (3) is finished off, radially to the inside between the carcass reinforcement (1) and the radially inner working ply (32) closest to said carcass reinforcement (1), by a so-called triangulation ply (31) of inextensible reinforcement elements, forming with the circumferential direction an angle greater than 60° and of the same direction as that of the angle formed by the reinforcement elements of said working ply (32). 6. A tyre as claimed in Claim 5, wherein in that the triangulation ply (31) has an axial width L31 greater than the width L32, L34 of the widest working ply (32, 34). Dated 1st day of November , 2000 (RITUSHKA NEGI) OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Documents:

abstract1.jpg

IN-PCT-2000-00579-MUM-CORRESPONDENCE(26-3-2010).pdf

IN-PCT-2000-00579-MUM-FORM 26(26-3-2010).pdf

in-pct-2000-579-mum-cancelled page(15-6-2004).pdf

in-pct-2000-579-mum-claims(granted)-(15-6-2004).doc

in-pct-2000-579-mum-claims(granted)-(15-6-2004).pdf

in-pct-2000-579-mum-correspondence(15-6-2004).pdf

in-pct-2000-579-mum-correspondence(ipo)-(19-7-2007).pdf

in-pct-2000-579-mum-drawing(15-6-2004).pdf

in-pct-2000-579-mum-form 1(1-11-2000).pdf

in-pct-2000-579-mum-form 1a(15-6-2004).pdf

in-pct-2000-579-mum-form 2(granted)-(15-6-2004).doc

in-pct-2000-579-mum-form 2(granted)-(15-6-2004).pdf

in-pct-2000-579-mum-form 3(1-11-2000).pdf

in-pct-2000-579-mum-form 3(15-6-2004).pdf

in-pct-2000-579-mum-form 4(11-3-2004).pdf

in-pct-2000-579-mum-form 5(1-11-2000).pdf

in-pct-2000-579-mum-form 6(15-6-2004).pdf

in-pct-2000-579-mum-form-pct-ipea-409(1-11-2000).pdf

in-pct-2000-579-mum-form-pct-isa-210(1-11-2000).pdf

in-pct-2000-579-mum-petition under rule 137(15-6-2004).pdf

in-pct-2000-579-mum-petition under rule 138(15-6-2004).pdf

in-pct-2000-579-mum-power of authority(1-11-2000).pdf

in-pct-2000-579-mum-power of authority(15-6-2004).pdf