Title of Invention	A TYRE HAVING A RADIAL CARCASS REINFORCEMENT
Abstract	A TYRE HAVING A RADIAL CARCASS REINFORCEMENT

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [See Section 10; rule 13] "A TYRE HAVING A RADIAL CARCASS REINFORCEMENT" SOCIETE DE TECHNOLOGIE MICHELIN, a French company of 23, rue Breschet, FR-6300 Clermont-Ferrand, France, and MICHELIN RECHERCHE ET TECHNIQUE S.A., a Swiss company, of Route Louis Braille, 10 et 12, CH-1763, Granges-Paccot, Switzerland, The following specification particularly describes the invention and the manner in which it is to be performed: 21 JUL 2005 The present invention relates to a tyre having a radial carcass reinforcement. The present invention relates to a tyre with radial carcass reinforcement, and more particularly to a "heavy-vehicle"-type tyre, intended to be fitted on a vehicle such as a lorry, road tractor, bus, trailer and others. More specifically, it relates to a novel bead structure. Generally, a tyre of the type in question comprises a carcass reinforcement formed of at least one ply of metal cables, which is anchored in each bead to at least one bead wire, forming an upturn. The carcass reinforcement is radially surmounted by a crown reinforcement, composed of at least two plies of metal cables, crossed from one ply to the next and forming angles of between 10° and 45° with the circumferential direction. The carcass reinforcement upturns are generally reinforced by at least one ply of metal cables oriented at a small angle relative to the circumferential direction. In the case of the tyre in question, the reinforcement ply of the bead may be wound around the bead wire, so as to have an axially outer strand and an axially inner strand, the radially upper end of the axially inner strand being generally located beneath the radially upper end of the axially outer strand. The known solution aims to avoid deradialisation of the cables of the upturn of the carcass reinforcement, and to minimise the radial and circumferential deformations to which the end of said upturn, and the outer layer of rubber covering the bead and effecting the connection to the rim are subjected. 2 French Application FR 98/09451 of 23rd July 1998, in order to improve the endurance of a tyre having beads intended to be mounted on rim seats which are flat or are inclined at 5°, uses a bead reinforcement armature having radial elements. The tyre described in said application has each bead provided with a first reinforcement armature formed of at least one ply of radial reinforcement elements which is wound around the anchoring bead wire of the carcass reinforcement and on the inside of said carcass reinforcement to form two strands such that the axially inner strand, between its radially upper edge parallel to the meridian profile of the carcass reinforcement and its point of tangency to the anchoring bead wire, follows a rectilinear trace referred to as "shortest-path" and that the radially upper end of said axially inner strand is radially located at a distance HL, from the base of the bead of between 80% and 160% of the distance HRNC, the radial distance between the end of the carcass reinforcement upturn and the base of the bead, the second armature of elements inclined relative to the radial direction not being wound around said anchoring bead wire and arranged axially to the outside of the carcass reinforcement upturn. The radial reinforcement elements of the ply or plies of the bead reinforcement armature are preferably inextensible metallic elements, made of steel and in the form of cables. The French application referred to above furthermore proposes, in order to improve the resistance of the carcass reinforcement to rupture of reinforcement elements occurring in its portions which form an integral part of the beads, to impart to said portions the same profile as that of the bead reinforcement plies having radial elements, that is to say, a rectilinear profile. The Applicant" s research has shown that such a bead reinforcement structure with, in particular, a rectilinear meridian profile of the main part of the carcass reinforcement which is at a tangent to the anchoring bead wire could be substantially improved by a judicious selection of the vulcanised rubber mixes forming the bead of the tyre. The tyre according to the invention, having a radial carcass reinforcement, anchored in each bead to an anchoring bead wire to form an upturn, the anchoring bead wire being surmounted radially by a first profiled member of vulcanised rubber mix and of a substantially triangular shape when viewed in meridian section, the upper edge of the upturn being separated from the main part of said reinforcement by a second profiled member of vulcanised rubber mix, is characterised in that the secant modulus of elasticity in tension of the first profiled member, measured for a relative elongation of 10%, is between 8 and 10 MPa, whereas the secant modulus of elasticity in tension of the second profiled member, measured under the same conditions, is between 3 and 5 MPa, a third profiled member of vulcanised rubber mix being arranged axially to the outside of the carcass reinforcement upturn and the secant modulus of elasticity in tension of which, measured under the same conditions, is between 35 and 50 MPa, whereas a fourth profiled member radially surmounting the third profiled member has a secant modulus of elasticity in tension, measured under the same conditions, of between 3 and 5 MPa, the radially lower end of said fourth profiled member being located radially at a distance less than the distance between the end of the upturn of the carcass reinforcement and 4 the base D of the beads, the third profiled member having a thickness which decreases radially towards the outside, such that the radial distance separating from the straight line D the point of the straight line parallel to the axis of rotation for which said thickness is equal to 10% of the maximum thickness is less than the radial distance between the end of the carcass reinforcement upturn and said straight line D, and said main part of the carcass reinforcement having a substantially rectilinear meridian profile between its point of tangency T to the anchoring bead wire and a point A located at a distance Hfl from the base D of between 35% and 65% of the radial distance HE between the points of maximum axial width of said carcass reinforcement and said base D. The presence of a third profiled member of very high modulus of elasticity and included. axially between the carcass reinforcement upturn and the layer of rubber mix which effects the contact with the rim flange and the secant modulus of elasticity in tension of which is between 10 and 15 MPa, avoids virtually any rotational movement of the anchoring bead wire of the carcass _ reinforcement, whatever the structure of said bead wire, the effect obtained however being significantly greater for a bead wire of the "braided" type. It is particularly advantageous for the third profiled member to be extended, radially to the inside, so as to be able to be turned up about the bead wire assembly and thus to cover at least half a circumference of the above assembly. "Bead wire assembly" is to be understood to mean an assembly formed mainly of the bead wire, the carcass reinforcement and possibly one or more additional reinforcement armatures. 5 The anchoring bead wire of the carcass reinforcement is generally surrounded by a layer of vulcanised mix: the secant modulus of elasticity in tension of said layer which surrounds the anchoring bead wire will be substantially equal to the secant modulus of elasticity in tension of the third profiled member. The life of the bead comprising such profiled members will be improved by the addition, between the main part of the carcass reinforcement and the carcass reinforce¬ment upturn, of a reinforcement armature formed of a ply of radial reinforcement elements which is wound around the anchoring bead wire to form two strands, the radially upper end of the axially inner strand being radially located at a distance HLI from the base of the bead of between 80% and 160% of the distance HRNC, the radial distance between the end of the carcass reinforcement upturn and the base of the bead, located axially to the inside of the upturn of the carcass reinforcement, preferably having its radially upper end radially less far from the axis of rotation than the end of the carcass reinforcement upturn, the distance HLE between said end and the base of the bead being between 0.2 and 0.8 times the height HRNC of the carcass reinforcement upturn. The characteristics of the invention will be better understood with reference to the following description which refers to the drawing, which illustrates in non-limitative manner examples of embodiment, in which drawing: * Figure 1 is a diagram, viewed in meridian section, of a first bead variant according to the invention, * Figure 2 is a diagram of a second variant, and 6 Figure 3 is a diagram of a third variant. The bead B shown in Figure 1 is that of a 305/70 R 22.5 tyre, intended to be mounted on a rim comprising rim seats inclined at 15°. Around said bead wire (2) there is anchored a carcass reinforcement (1) composed of a single ply of practically inextensible metal cables, which is anchored in each bead to a bead wire (2) coated in a vulcanised layer of rubber (20) to form an upturn (10) . Between a point A, located at a distance Hfl from the base D of the beads [said base being by convention represented by the straight line parallel to the axis of rotation passing through the point of the bead wire (2) closest to said axis of rotation, equal to 50% of the radial distance HE between the points of maximum axial width of said carcass reinforcement and said base D, and its point of tangency T to the bead wire (2) provided with the coating layer (20), the carcass reinforcement (1) has in its main part a substantially rectilinear meridian profile. "Substantially rectilinear" is understood to mean, firstly, a rectilinear profile and, secondly, a slightly concave or convex profile, the deflection of which in its centre is at most equal to 1% of HE- The radial distance HRNC between the radially upper end of said upturn (10) and the base D of the bead being less than the distance Hfl in the example in question. Between the carcass reinforcement (1) and its upturn (10), radially above the bead wire (2), there is arranged a first profiled member or first bead filler (3) of vulcanised rubber mix, the secant modulus of elasticity in tension M10 of which is equal to 10 MPa. The modulus M10 represents, for a given rubber mix, the ratio between the tensile stress a10 for a relative elongation 5L/L of 10% and said elongation, L being the initial length of the test piece and 7 of the test piece. Said modulus M10 is determined in accordance with the standard AFNOR-NFT-46-002 of September 1988, under normal conditions of temperature and humidity in accordance with the standard AFNOR-NF-T40-1Q1 of December 1979. Said filler (3) is extended radially by a second profiled member or second bead filler (4) of vulcanised rubber mix of a secant modulus M10, measured under the same conditions as the previous one, of 4 MPa. Axially to the outside of the carcass reinforcement upturn (10) there is placed a third profiled member (5) of vulcanised rubber mix of substantially lozenge-shaped form, the secant modulus of elasticity in tension M10 of which is equal to 4 5 MPa. Said profiled member (5) is extended radially to the inside by a layer (5") of the same mix of substantially constant thickness and surrounding the assembly formed by the bead wire (2) and its coating (20). It is radially surmounted by a fourth profiled member (6) of vulcanised rubber mix of a secant modulus of elasticity in tension M10 of 4 MPa, and therefore equal to the modulus M10 of the second bead filler (4) . The radially upper end (3A) of the first filler (3) is located at a radial distance from the bead base D which is greater than the distance HRNC, whereas the radially lower end (4A) of the profiled member (4) is located radially, as known per se, below the end of the carcass reinforcement upturn. As for the radially upper end of the profiled member (4), it is substantially located at the level of the maximum axial width of the tyre. Whereas the radially upper end of the profiled member (6) (not shown) is substantially located, like the upper end of the profiled member (4), at the level of the maximum axial width of the tyre, while being 8 radially above said end of the profiled member (4), its junction with the third profiled member (5) is such that its radially lower end (6A) is spaced apart radially from the straight line D by a distance less than the distance HRMC between the end of the upturn (10) of the carcass reinforcement and said base D„ As for the radially upper end (5A) of the third profiled member (5), it may be located at a radial distance from the straight line D which may be less or more than the distance HRNC, but the thickness e of the profiled member (5), measured on a straight line parallel to the axis of rotation, radially decreasing towards the outside, the point C of the straight line parallel to the axis of rotation for which said thickness is egual to 10% of the maximum thickness eH being distant from the straight line D by a quantity which in all cases is less than the value HRNC. The layer (8) of vulcanised rubber mix which forms the outside of the bead B and effects the contact with the mounting rim has a secant modulus of elasticity in tension, in the example described, of 11 MPa. The bead B is finished off by a sidewall layer (9) and an inner layer (11), formed respectively of rubber mixes suitable for their functions. The second example, described and illustrated in Figure 2, differs from the example illustrated in Figure 1 by the presence between the carcass reinforcement (1) and its upturn (10) of an additional reinforcement armature (7) of the bead B. Axially to the outside of the non-upturned part of the carcass ply (1) and, after turning up around the bead wire (2), axially to the inside of the upturn (10) of the ply (1), there is arranged a bead reinforcement armature (7) composed, in the example described, of a single ply (70), so as to form two strands, an axially inner strand (701) and an 9 axially outer strand (702). The radially upper ends respectively of the two strands (701) and (702) are located relative to the base of the bead at heights HL] and HLE, the distances HLE and Hu being respectively equal to 40% and 150% of the distance HHNC. The ply (70) of said reinforcement is formed of radial metal cords or cables, in the example described oriented at 90° to the circumferential direction (reinforcement elements forming an angle within the range (-85°, +85") with the circumferential direction will be considered to be radial). Axially to the outside of the axially outer strand (702) of the reinforcement ply (70) and of the upturn (10) of the carcass reinforcement (1), there is located the filler (5) of very high modulus of elasticity, since it is equal in this case to 40 MPa, said filler (5), as in the preceding cases, being radially surmounted by a profiled member (6) having the same properties as the profiled members (6) referred to in the examples of Figures 1 and 2. The edge of the axially inner strand (701) and the axially outer edge (702) of said ply (70) are axially substantially parallel respectively to the non-upturned part and to the upturn (10) of the carcass ply (1), while being decoupled from said part and said upturn by a layer of rubber mix (40). The third variant, shown in Figure 3, differs from the variant of Figure 1 in that the upturn (10) of the carcass reinforcement (1) axially forms a tangent to the main part of the carcass reinforcement in the region around the point A previously defined and in which the carcass reinforcement (1) has a substantially rectilinear meridian profile. "Region around the point A" is to be understood to mean a radial distance of at most 20% of the radial distance HE between the points of maximum axial width of said carcass reinforcement and the base D of the bead. In the case specifically 10 described, the point of tangency T" between the main part of the carcass reinforcement (1) and its upturn (10) is at a radial distance HT, from the base D equal to 35% of the height H£, whereas the point A is at the distance Hfl equal to 50% of HE. Axially below said point of tangency T" , the carcass reinforcement (1) and upturn (10) are axially separated by a first bead filler (3), the secant modulus of extension of which is equal to 10 MPa. Radially above the point T" there is located a decoupling layer (4* ), between the upper edge of the upturn (10) ("edge of a reinforcement ply" is to be understood to mean a part of said ply having, starting from its end, a length of at least 15 mm), and in particular the end of said upturn (10), and the main part of the carcass reinforcement (1) , said layer possibly having a constant thickness, generally between two and three times the thickness of the carcass reinforcement and the rubber mix constituting said layer (4" ) having the same composition and properties as the mix of the profiled member (4) used in the preceding two examples. Axially to the outside of the upturn (10) there are arranged two profiled members (5) and (6) formed respectively of the same mixes as those of the profiled members (5) and (6) of the first example described, the radially lower end (6A) of the profiled member (6) being located radially slightly above the point of tangency T" . The profiled member (5) has the special feature of being extended by a layer (5") formed of the same mix as the mix of the profiled member (5), but of variable thickness so as to have a virtually triangular shape in the region of the toe of the bead. WE CLAIM: 1. A tyre having a radial carcass reinforcement (1), anchored in each bead B to an anchoring bead wire (2) to form an upturn (10), the anchoring bead wire (2) being surmounted radially by a first profiled member (3) of vulcanised rubber mix and of a substantially triangular shape when viewed in meridian section, the upper edge of the upturn (10) being separated from the main part of said carcass reinforcement (1) by a second profiled member (4) of vulcanised rubber mix, characterised in that the secant modulus of elasticity in tension Mio of the first profited member (3) is between 8 and 10 MPa, whereas the secant modulus of elasticity in tension Mio of the second profiled member (4) is between 3 and 5 MPa, a third profiled member (5) of vulcanised rubber mix being arranged axially to the outside of the carcass reinforcement upturn (10) and the secant modulus of elasticity in tension Mio of which is between 35 and 50 MPa, whereas a fourth profiled member (6) radially surmounting the third profiled member (5) has a secant modulus of elasticity in tension Mio of between 3 and 5 MPa, the radially lower end (6A) of said fourth profiled member (6) being located radially at a distance less than the distance HRNC between the end of the upturn (10) of the carcass reinforcement (1) and the base D of the beads, the third profiled member (5) having a thickness e which decreases radially towards the outside, such that the radial distance separating from the straight line D the point C of the straight line parallel to the axis of rotation for which said thickness e is equal to 10% of the maximum thickness em, is less than the distance HRNC, and said main part of the carcass reinforcement having a substantially rectilinear meridian profile between its point of tangency T to the anchoring bead wire (2) and a point A located at a distance HA from the base D of between 35% and 65% of the radial distance HE between the points of maximum axial width of said carcass reinforcement (1) and said base D, said tyre has a layer of rubber mix which effects contact with the rirri flange. 12 2. A tyre as claimed in claim 1, wherein the secant modulus of elasticity in tension of said layer of rubber mix is between 10 and 15 MPa. 3. A tyre as claimed in claim 1, wherein the anchoring bead wires (2) are bead wires of the "braided" type. 4. A tyre as claimed in claim 1 wherein the secant modulus of elasticity in tension Mio of the layer of vulcanised mix (20) which surrounds the anchoring bead wire (2) of the carcass reinforcement (1) equal to the secant modulus of elasticity in tension Mio of the third profiled member (5). 5. A tyre as claimed in one of claims 1 to 4, wherein the third profiled member (5) is extended radially to the inside by a layer {5) of the same mix and of substantially constant thickness, so as to be able to be turned up around the bead wire assembly (2), and thus to cover at least half the circumference of said assembly. 6. A tyre as claimed in one of claims 1 to 5, wherein an additional reinforcement armature formed of a ply (70) of radial reinforcement elements which is wound around the anchoring bead wire (2) to form two strands (701) and (702) respectively axially to the outside of the main part of the carcass reinforcement (1) and axially to the inside of the upturn (10), the radially upper end of the axially inner strand (701) being radially located at a distance HLI from the base of the bead of between 80% and 160% of the distance HRNC, the radial distance between the end of the upturn (10) of the carcass reinforcement (1) and the base D of the bead, and the axially outer strand (702) , having its radially upper end radially less far from the axis of rotation than the end of the carcass reinforcement upturn (10), the distance HLE 13 between said end and the base D of the bead being between 0.2 and 0.8 times the height HRNC of the carcass reinforcement upturn (10). A tyre as claimed in one of claims 1 to 5, wherein the upturn (10) of the carcass reinforcement (1) which forms a tangent at T" to the main part of said reinforcement (1), the point T" being located radially in the region extending over a radial distance of at most 20% of the radial distance HE, around the point A., the carcass reinforcement (1) and its upturn (10) , radially below said point of tangency T, being axially separated by a second profiled member (3) the secant modulus of extension of which is between 8 MPa and 10 MPa, and the upper edge of the upturn (10), in particular the end of said upturn (10), radially above the point T , being axially separated from the main part of the carcass reinforcement (1) by a decoupling layer (4" ) of vulcanised rubber mix of a secant modulus of elasticity M10 of between 3 and 5 MPa. Dated this 15th day of June, 2001. (RITUSHKA NEGI) OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS 14

Documents:

IN-PCT-2001-00714-MUM-CORRESPONDENCE(21-9-2012).pdf

IN-PCT-2001-00714-MUM-FORM 16(6-8-2012).pdf

in-pct-2001-714-mum-abstract(21-7-2005).doc

in-pct-2001-714-mum-abstract(21-7-2005).pdf

in-pct-2001-714-mum-cancelled pages(15-6-2001).pdf

in-pct-2001-714-mum-claims(granted)-(21-7-2005).doc

in-pct-2001-714-mum-claims(granted)-(21-7-2005).pdf

in-pct-2001-714-mum-correspondence(22-3-2006).pdf

in-pct-2001-714-mum-correspondence(ipo)-(26-7-2004).pdf

in-pct-2001-714-mum-drawings(21-7-2005).pdf

in-pct-2001-714-mum-form 1(15-6-2001).pdf

in-pct-2001-714-mum-form 19(27-4-2004).pdf

in-pct-2001-714-mum-form 1a(21-7-2005).pdf

in-pct-2001-714-mum-form 2(granted)-(21-7-2005).doc

in-pct-2001-714-mum-form 2(granted)-(21-7-2005).pdf

in-pct-2001-714-mum-form 3(15-6-2001).pdf

in-pct-2001-714-mum-form 3(21-7-2005).pdf

in-pct-2001-714-mum-form 3(25-5-2004).pdf

in-pct-2001-714-mum-form 5(15-6-2001).pdf

in-pct-2001-714-mum-form-pct-ipea-409(15-6-2001).pdf

in-pct-2001-714-mum-petition under rule 137(22-7-2005).pdf

in-pct-2001-714-mum-petition under rule 138(22-7-2005).pdf

in-pct-2001-714-mum-power of authority(15-6-2001).pdf

in-pct-2001-714-mum-power of authority(21-7-2005).pdf