GB801994A - Dual compartment tire - Google Patents

Abstract

801,994. Safety tyres. GOODYEAR TIRE & RUBBER CO. Oct. 5, 1956 [June 4, 1956], No. 30401/56. Class 144 (2). In a tubeless tyre 3 and wheel rim 1 assembly wherein a safety diaphragm 21 of substantially inextensible, or low stretch, material is sealed to the beads 4 of the tyre 3 to divide the air space into radially inner and outer chamber 13, 12, the diaphragm is sufficiently impervious to air to permit use of the tyre in the event of deflation of the outer chamber 12, Fig. 2, for a distance of at least 30 miles at a speed in the order of 30 m.p.h., means being provided for reducing friction between the opposed walls of the outer chamber when the latter is deflated. Inflation of the two chambers 13, 12 is effected through separate inflation valves 2, 10 fitted in the rim 1 and the tyre sidewall respectively. As shown the diaphragm is comprised of two superposed crossed rubberized plies 16, 17, Fig. 9, of parallel nylon cord of high stretch from which most of the stretch has been removed, the cords of the plies subtending an angle of 32 degrees with the circumferential centre line of the diaphragm and the edges 7 of the diaphragm being clamped, and possibly cemented, between the tyre beads 4 and the rim flange portions 5, 8 and terminating in beaded portions lying flush with the rim edges. The diaphragm encloses an inner chamber 13 of at least 60 per cent of the total air space of the tyre and may have a permissible stretch to increase this capacity, on deflation of the outer chamber, by 10 to 20 per cent, but insufficient to restore the normal height of the tyre. An inner lining 19 of butyl rubber renders the diaphragm substantially air-impervious, but if desired the diaphragm may be slightly porous so that topping-up inflation of the outer chamber may be effected via the valve 2 and diffusion through the diaphragm. Where substantially air-impervious, the inner chamber 13 may be inflated to a higher pressure than the separately inflated outer chamber. To reduce friction between the contacting surfaces of the diaphragm and tyre, Fig. 2, on deflation of chamber 12, either or both of the said surfaces are coated with a lubricant such as a silicone oil, silicone grease, paraffin, polyalkylene glycols or liquid polyesters prepared from dibasic carboxylic acids and glycols having an average molecular weight of approximately 1500. The valve 10, Figs. 4-6, comprises a rubber cylinder having an axial through slit 11, and domed end flanges 24, 23 which embrace the inner and outer surfaces respectively of the tyre wall after insertion, as by a rod 27 engaged in the initially blind slit 11, in an opening 9, in the tyre wall, which is approximately half the diameter of the valve body 22. The resultant compression of the valve body effectively closes the slit 11 but permits insertion of a hollow inflating needle 28 having a tapered end 29 and a lateral opening 30. In an alternative form the end 23 of the valve is frusto-conical to engage in a countersunk recess in the tyre wall.