Self-supporting radial pneumatic tire for motor vehicle has rubber coated metal alloy cords with memory retention for lower elastic modulus at temperatures below a phase reversal temperature than above this temperature

摘要

Inserts(9,10,12) for supporting the tire when deflated due to puncture consist of radially aligned cords embedded in rubber. The cords are made from a memory-retaining alloy or include such material. At tire operating temperatures of not 50[deg]C the cords have a lower modulus of elasticity than at temperatures above 60[deg]C after exceeding the phase reversal temperature. A single insert may lie inside or outside the carcass layer(4) and covers a large proportion of the sidewall(8) length, typically extending from the side of the bead wire(6) to the side of the breaker layer(2). The single insert lies outside the turned up free end of the carcass and extends as far as the top of the bead wire. Two inserts(9,10) may be included in each sidewall and overlap each other in the central area of the sidewall. In the latter case one insert is on the inside of the carcass and the other on the outside, the inner insert preferably extending underneath the edge of the breaker layer. An additional layer(11) lies between the inner layer(5) and carcass(4). The latter layer has cords of memory retaining alloy, is positioned centrally relative to the breaker layer and extends over 30-50% of the breadth of the broadest reinforcing layer in the breaker layer. Cords in the additional layer are at a right angle to the tire circumference. Cords in all inserts can be either of monofilaments or multi-filaments, typically at least one filament can be of a memory-retaining alloy and at least one other of another metal or a textile. The round cross-section cords have a diameter of 0.1-2mm, preferably 0.6-1mm. Each insert(9,10,11,12) may comprise one or more layers of parallel cords. 4--500 cords are arranged across a 10cm breadth. Cord modulus of elasticity at not 50[deg]C is 20-40GPa and above 60[deg]C is 70-80GPa.