Title of Invention

A TYRE WITH RADIAL CARCASS REIN FOR CEMENT

Abstract

A tyre P, which is intended to be mounted on a rim, the seats of which form an angle with the axis of rotation of between 0° and 6°, and comprises a radial carcass reinforcement (1) anchored within each bead B to a bead wire (2) so forming an upturn (10), said bead wire (2) being radially surmounted, axially between the main portion of the reinforcement (1) and its upturn (10), by at least one rubber mix profile (3) substantially triangular in form and of an elevated Shore A hardness at least equal to 85 points, characterized in that the meridian profile of the axially outer surface of each bead B, composed of a first curved portion NA intended to enter into and remain in permanent contact with the bead flange and exhibiting with a second curved portion AR an abrupt discontinuity of curvature, is combined with the presence of a rubber mix profile (3) of the height HL, in such a way that said profile is axially in contact over its entire height with the upturn (10) of the carcass reinforcement (1) and separated from the main portion of said reinforcement (1) by a rubber mix profile (4) of a low hardness at most equal to 60 points, a third low Shore A hardness rubber mix profile (5) being disposed axially to the outside of the upturn (1) of the carcass reinforcement (1) between the protector (6) which covers the bead B axially to the outside and said upturn (10).

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10 ; rule 13] SOCIETE DE TECHNOLOGIE MICHELIN, a French company, of 23 rue Breschet, F-63040 Clermont-Ferrand, France and MICHELIN RECHERCHE ET TECHNIQUE S.A., a Swiss company, of Route Louis Braille, lOet 12, CH-1763 Granges Paccot, Switzerland. The following specification particularly describes the nature of the invention and the manner in which it is to be performed :- The present invention relates to a tyre with radial carcass reinforcement, more particularly intended to be mounted on a rim of the "heavy-vehicle" type, the seats of which are inclined relative to the axis of rotation at an angle a, which is such that 0° Said rims exhibit the peculiarity of having relatively high rim flanges according to the standards in force (TRA, ETRTO, JATMA), and the tyres which use such rims are generally tyres mounted with an inner tube accompanied by a flap disposed between the inner walls of the two tyre beads. Said beads each comprise in known manner a bead wire, generally of the "braided" type, around which there is anchored by winding a carcass reinforcement of metal reinforcement elements, forming an upturn whose height measured relative to the base of the bead is greater than the height of the rim flange. Said upturn is reinforced axially to the outside by an additional reinforcement of metal elements oriented relative to the circumferential direction at a slight angle, which may be between 5° and 30°. Said reinforcement is wound around the anchoring bead wire and forms two strands: an axially outer strand, the end of which is situated radially slightly above the end of the carcass reinforcement upturn, and an axially inner strand, the end of which is generally situated below a straight line parallel to the axis of rotation and passing through the crown of the rim flange. The main purpose of said additional reinforcement is to minimise the movement in the three dimensions on the one hand of the carcass reinforcement upturn end and on the other hand of the protective layer of rubber mix, also known as a protector, which surrounds the surface of the bead which has to be in contact with the operating rim. Any reinforcement armature formed of metal elements or other elements is costly, and much research has been carried out with a view to dispensing with the bead reinforcement armature without thereby affecting the fundamental properties of the tyre bead, i.e. ensuring that said tyre remains on its operating rim whatever the driving conditions and for the longest possible period, which requires that any solution exhibit excellent properties with regard to endurance and resistance to rim wear. The problem of resistance to rim flange wear, resulting from repeated flexure of the tyre and movement between beads and rim flanges, seemed to have been solved by the adoption, for the outer surface of the bead, of a suitable meridian profile, said profile consisting of a first curved portion which has to come into and remain in permanent contact with the surface of the rim flange, said first portion having at its junction with a second curved portion an abrupt discontinuity of curvature, the meridian profile of which second portion is such that it cannot in any case come into contact with the surface of the rim flange. The discontinuity between two curves may be defined geometrically as being the acute angle, viewed in meridian section, formed by the tangents to the two curves respectively at the junction point. The discontinuity is abrupt if said angle is at least equal to 35°. Such a solution is disclosed and described in patent FR 2 406 530. This has proven insufficient to compensate for the lack of wear resistance exhibited by the bead, which lack is caused by the absence of an additional bead reinforcement armature. In order to compensate for said lack of wear resistance, the tyre, which is intended to be mounted on a rim, the seats of which form an angle with the axis of rotation of between 0° and 6°, and comprises a radial carcass reinforcement anchored within each bead to a bead wire so forming an upturn, said bead wire being radially surmounted, axially between the main portion of the reinforcement and its upturn, by at least one rubber mix profile substantially triangular in form and of an elevated Shore A hardness, is characterised in that the meridian profile of the axially outer surface of each bead, composed of a first curved portion intended to enter into and remain in permanent contact with the bead flange and exhibiting with a second curved portion an abrupt discontinuity of curvature, is combined with the presence of a rubber mix profile of the height HL, radially above the bead wire and axially between the main portion of the carcass reinforcement and its upturn, in such a way that said profile is axially in contact over its entire height with the carcass reinforcement upturn and separated from the main portion of said reinforcement by a low hardness rubber mix profile, a third low hardness rubber mix profile being disposed axially to the outside of the carcass reinforcement upturn between the protector which covers the bead B axially to the outside and said upturn. A rubber mix of elevated Shore A hardness is understood to mean a mix whose hardness is at least equal to 85 points. A rubber mix of low Shore A hardness is understood to mean a mix whose hardness is at most equal to 60 points. In known manner, the rubber profile radially above the bead wire is generally such that its upper end is attached to the main portion of the carcass reinforcement, in such a way that said profile is virtually not in contact with the upturn of said reinforcement. The invention inverts this positioning, the upper end of the profile being attached to the upturn, and this inverted positioning of the profile of high hardness rubber mix, in combination with the meridian profile of the outer surface of the bead, allows the conventional additional reinforcement armature to be omitted and thus the cost price to be reduced without the tyre losing bead endurance and wear resistance. The wear resistance of the bead protector and the endurance of the bead may advantageously be improved by the presence of a third profile of a mix of low Shore A hardness, lower than the hardnesses of the same type of the profiles between carcass reinforcement and upturn, and at most equal to 55 points. The features of the invention will be better understood with the aid of the description which follows and which makes reference to the drawings, which illustrate examples of embodiment in non-limiting manner and of which the single Figure 1 is a schematic representation of a tyre structure according to the invention. The tyre P, of size 12 00. R. 24, is intended to be mounted on an 8.50-24 rim, the seats of which are inclined relative to the axis of rotation of said rim by an angle of 5°. Said tyre comprises a tread (not shown) connected to two beads B by means of two sidewalls 7, and is reinforced on the one hand by a crown reinforcement (not shown) and on the other hand by a carcass reinforcement which, in the case described, is formed of a single ply 1 of metal cables made of steel. Said ply 1 is anchored within each bead B by winding around a bead wire 2, so forming an upturn 10, the end of which is situated at a radial distance from the base of the bead which is substantially equal to 30% of the height of the tyre P (the base of the bead is understood to mean, viewed in meridian section, the straight line parallel to the axis of rotation passing through the point of intersection of the generatrix of the bead seat and the straight line of the bead flange, said straight line being perpendicular to the axis of rotation). Radially above the bead wire 2 and axially between the non-upturned portion of the carcass ply 1 and its upturn 10 there is disposed a first profile 3 of a rubber mix of a Shore A hardness of 97. With a substantially triangular shape and a height HL, measured relative to the base of the bead and markedly greater than the height HR of the rim flange, said profile has its radially upper end C attached to the upturn 10 and is thus in contact with said upturn over the entire extent of its height, while the end C is separated from the non-upturned carcass ply portion by a second profile 4 of rubber mix of a lower Shore A hardness of 56. The shape of said profile 4 is such that its radially lower end D is situated at a radial distance H2 from the base of the bead of less than the height HR in such a way that the axially inner face of the profile 3 is in contact, over a very shallow depth, with the non-upturned portion of the carcass ply 1. The radially upper end of the profile 4 is situated radially above the end of the carcass ply upturn 10. The bead B is covered externally with a protective layer 6 or protector, of a very hard rubber mix, which protector ensures contact with the seats and flange of the operating rim. Said protector 6 is in contact with the upturn 10 of the carcass ply 1 over the height H1 so as then to be separated from said upturn by a third profile 5 of a rubber mix of low Shore A hardness, at most equal to 55 and in the case described equal to 47. Of lenticular shape, said profile 5 extends radially over a height such it covers the end of the upturn 10. The meridian profile of the axially outer surface of the bead B and of the sidewall 7 consists of a straight segment MN perpendicular to the axis of rotation extended radially to the outside by a concave arc of a circle NA, the portion MA having to be in permanent contact with the rim flange. The point A is the point of abrupt discontinuity with the concave arc of a circle AR, which extends radially to the outside the arc NA, said arc AR never coming into contact with the rim flange. The arc AR forms a tangent radially to the outside with the convex arc of a circle of sidewall 7. At the point A, the tangents respectively to the arcs of circles NA and AR form between them an acute angle β equal to 40°. WE CLAIM: 1 A tyre P, which is intended to be mounted on a rim, the seats of which form an angle with the axis of rotation of between 0° and 6°, and comprises a radial carcass reinforcement (1) anchored within each bead B to a bead wire (2) so forming an upturn (10), said bead wire (2) being radially surmounted, axially between the main portion of the reinforcement (1) and its upturn (10), by at least one rubber mix profile (3) substantially triangular in form and of an elevated Shore A hardness at least equal to 85 points, characterized in that the meridian profile of the axially outer surface of each bead B, composed of a first curved portion NA intended to enter into and remain in permanent contact with the bead flange and exhibiting with a second curved portion AR an abrupt discontinuity of curvature, is combined with the presence of a rubber mix profile (3) of the height HL, in such a way that said profile is axially in contact over its entire height with the upturn (10) of the carcass reinforcement (1) and separated from the main portion of said reinforcement (1) by a rubber mix profile (4) of a low hardness at most equal to 60 points, a third low Shore A hardness rubber mix profile (5) being disposed axially to the outside of the upturn (1) of the carcass reinforcement (1) between the protector (6) which covers the bead B axially to the outside and said upturn (10). 2 A tyre as claimed in claim 1, wherein the third rubber mix profile (5) has a Shore A hardness lower than the hardnesses of the same type of the profiles (3,4) between carcass reinforcement (1) and upturn (10), and at most equal to 55 points. Dated this 22nd day of October, 2002. (RANJNA MEHTA-DUTT) of Remfry & Sagar Attorney for the Applicants

Documents:

abstract1.jpg

in-pct-2002-01459-mum-cancelled pages(22-09-2005).pdf

in-pct-2002-01459-mum-claims(granted)-(22-09-2005).doc

in-pct-2002-01459-mum-claims(granted)-(22-09-2005).pdf

in-pct-2002-01459-mum-correspondence 1(26-10-2005).pdf

in-pct-2002-01459-mum-correspondence 2(23-03-2007).pdf

IN-PCT-2002-01459-MUM-CORRESPONDENCE(26-3-2010).pdf

in-pct-2002-01459-mum-correspondence(ipo)-(14-03-2007).pdf

in-pct-2002-01459-mum-drawing(22-09-2005).pdf

in-pct-2002-01459-mum-form 18(24-03-2005).pdf

in-pct-2002-01459-mum-form 1a(21-10-2002).pdf

in-pct-2002-01459-mum-form 2(granted)-22-09-2005).doc

in-pct-2002-01459-mum-form 2(granted)-22-09-2005).pdf

IN-PCT-2002-01459-MUM-FORM 26(26-3-2010).pdf

in-pct-2002-01459-mum-form 3(14-03-2005).pdf

in-pct-2002-01459-mum-form 3(22-09-2005).pdf

in-pct-2002-01459-mum-form 3(22-10-2002).pdf

in-pct-2002-01459-mum-form 5(11-12-2001).pdf

in-pct-2002-01459-mum-form-pct-isa-210(22-09-2005).pdf

in-pct-2002-01459-mum-petition under rule 137(22-09-2005).pdf

in-pct-2002-01459-mum-power of authority(19-10-2002).pdf