Shock-proof pyro mechanism for use in space applications, e.g. strap cutter used in launcher or satellite, includes low melting point metal that produces shock absorbing function when melted

摘要

The mechanism includes a low melting point material (300) such as paraffin or a eutectic alloy, at least one electric or highly exothermal pyrotechnical composition heater (400), and a device suitable for throttling the low melting point material (300) in the liquid state, after the heater is actuated, thus performing a shock-absorbing function. The device further includes at least two concentric surfaces (154, 216; 152, 218) defining, a set of clearances between them and provided respectively on ring and piston parts (150, 200) that are capable of moving in order to throttle the low melting point material (300) through the set of clearances defined between the concentric surfaces. - Before an electrical initiator (180) is used to initiate the pyrotechnical composition, the soldered connection constituted by the low melting point metal at the interfaces between a cylindrical part 156 and the middle diameter piston segment (216) and between the another cylindrical part 152 and the largest diameter piston segment (218), and also the solid phase of this metal situated inside the a chamber (310), provides reliable and effective blocking of the structure ensuring that two assemblies (100 and 200) are prevented from moving relative to each other, with a ring (150) being prevented from moving relative to a body (110) and to a plug (130). In this position, the small section (214) of the piston (200) can emerge at least in part to the outside of the assembly (100). When the electrical initiator (180) is powered, the pyrotechnical composition is triggered to rapidly raises the temperature of the metal to melt it, thereby releasing the piston relative to the assembly (100). The gas coming from the chemical reaction of the pyrotechnical composition causes the chamber (220) to expand and thus moves the piston away from the plug in translation along the axis O-O. This displacement of the piston reduces the volume of the chamber (310) and thus transfers the low melting point metal by throttling it between the adjacent surfaces of the ring (150) and of the piston, thus performing a damping function on the movement. The low melting point metal then re-solidifies to reconstitute the solder connection and finally block the device in a new state in which the piston extends further from the second end of the body (100) than it did in the initial state.