Patent GB-1373359-A (GB)
Title: Pneumatic tyres
IPC: B60C9/07
Filed: 1971-10-19
Abstract: 1373359 Pneumatic tyres MICHELIN & CIE 19 Oct 1971 [19 Oct 1970 30 July 1971] 48619/71 Heading B7C A pneumatic tyre comprises a carcass reinforced with cord plies, e.g. 10, 11, each of which is continuous from one bead wire 6 of the tyre to the other and in each of which the cord orientation relative to the radial planes containing the axis of rotation of the tyre varies progressively and without sudden change as the cords pass from one bead wire to the other, each cord making an oblique angle with the radial planes in the region beneath the tyre tread 2 and in the regions between the midheight 7 of each sidewall 4 and the associated bead wire 6, and following an S-shaped path in the regions between each mid-height and the associated tyre shoulder 8, a pair of radial planes, Y Y<SP>1</SP> and Z Z<SP>1</SP>, being tangential at respective points, 14, 15, to the S-shaped path. As shown in Fig. 1, the carcass may consist of two cord plies 10, 11 of which one is cross-laid with respect to the other, and each carcass ply may be turned up around the bead wires 6. The distance between the points 14, 15 may be from 1/6-1/3 of the radial height of the associated sidewall 4, and the angle between the planes Y Y<SP>1</SP> and Z Z<SP>1</SP> may be from 1-5 times the angle between the plane Y Y<SP>1</SP> and the plane tangential to the corresponding point of the S-shaped path of an adjacent cord within the same ply. The tyre may be provided with a breaker assembly, (Fig. 6, not shown), comprising at least two plies of cords (e.g. of steel), cross-laid with respect to one another (e.g. at angles of 69 degrees to the radial planes), and superposed on a layer of rubber (e.g. having a modulus of elasticity of 115 kg/cm<SP>2</SP> at 100% elongation). Specific examples given of the angle made by the carcass cords with the radial planes are 40-45 degrees in the regions between each bead wire 6 and the associated mid-height 7, and 74À5 and 51 degrees beneath the tread 2 in the Fig. 1, and (Fig. 6) embodiments respectively. The carcass cords may each comprise 3 strands of 1100 denier polyester, and are calendered in rubber whose modulus of elasticity at 100% elongation is 39 kg/mm<SP>2</SP>. in the case of the Fig. 1, embodiment and 115 kg/mm<SP>2</SP>. in the case of the (Fig. 6) embodiment. The tyre carcass is made from elongate cord plies each of the form shown in Fig. 4, having a central portion and two lateral portions in which the cords are inclined to the longitudinal direction of the ply in the same direction and two intermediate portions 23 joining the central and lateral portions in which the cords are oppositely inclined to the longitudinal direction of the ply. The cord angle in the portions 23 may either be equal to, or not differ by more than 15 degrees from the cord angle in the remaining portions of the ply. The tyre carcass is initially made in cylindrical form and during the subsequent shaping and vulcanization stages in the manufacture of the tyre the path followed by the carcass cords is caused to change from that shown in Fig. 4, to that shown in Fig. 1. A formula is given in the Specification which relates the spacing of the cords in each carcass ply to other parameters of the tyre. Specification 1,252,939, is referred to.