Resettable separation nut with a low level of induced shock

#The technical field of the invention is that of devices for connecting and separating objects such as microsatellites with respect to a structure. More generally, the items concerned are devices for the placement of satellites from a rocket, the purpose of which is to unlock the satellite from its support and move it rapidly away therefrom by ejection.

#In this patent application, the concepts of “separation nut”, “unlocking” and “unlocking device” are equivalent.

#More specifically, the invention relates to a separation nut intended to release a screw which holds two subassemblies of a structure together, this release taking place through the movement of a release ring by virtue of the gases produced by a gas generator.

#A detailed description of one preferred embodiment of the invention is given hereinafter with reference to FIGS. 1 and 2.

#FIG. 1 is a view in longitudinal axial section of an unlocking device according to the invention which has not yet operated.

#FIG. 2 is a view in longitudinal axial section of the device of FIG. 1 in the operating phase. Unlike what is shown in the figure, the spring never reaches its extreme stressed configuration, that is to say the configuration in which it is coil bound.

#With reference to FIG. 1, an unlocking device 1 according to the invention comprises a hollow body 2, a gas generator 3, a gas expansion chamber 4, a release ring 5, an ejector 6, a segmented nut 7, a connecting screw 8 and a shutter 9. The body 2 is an approximately cylindrical component with two free ends, one of which has a widened base 10 comprising, on a peripheral annulus, two diametrically opposed bores 11 each intended to take a screw so as to secure the said unlocking device 1 to the second subassembly. At its two ends, the said body 2 has two flared portions manifested by two hollow cylindrical parts whose inside diameter is greater than that of the central part of the said body 2. The first flared portion corresponds to the upstream part of the unlocking device 1 and partially constitutes the gas expansion chamber 4, the second flared portion corresponding to the downstream part of the said device 1, that is to say the one in which the widened base 10 of the body 2 is located, and being intended to accommodate a component known as a shutter 9. The shutter 9 is in the form of a flat disc comprising a central bore and extended by a peripheral flange which is threaded on its external lateral surface, the said shutter 9 being intended to be screwed into the said downstream flared portion. The release ring 5 is a hollow cylindrical component with two free ends, one of which has a widened base 12 with a flat circular outer face equipped with a central bore. The said ring 5 has, passing through it, a central duct of variable cross section which, overall, has an upstream part of small diameter passing through the widened base 12, and a downstream part of larger diameter which, on its internal lateral wall, has two annular projections 13 similar to two mutually parallel annuli, each projection 13 having an approximately trapezoidal cross section, the top of which is flat, thus defining a flat annular upper face. One of the two projections is located at the free end of the downstream part of the central duct of the ring 5. The said ring 5 grips a segmented nut 7 and a hollow cylindrical component known as a separator 14, these two components 7 and 14 being in contact and in continuity one with the other. The nut 7, which has a roughly cylindrical shape, is split into four identical segments on four mutually perpendicular radial planes and, when the four segments touch, the said nut 7 has a threaded central duct into which is screwed a connecting screw 8 that connects the two subassemblies. The external lateral surface of the said nut 7 has two annular projections 15 similar to two mutually parallel annuli, each projection 15 having a roughly trapezoidal cross section the top of which is flat, thus defining a flat annular upper face. One of the two ends of the nut 7 ends in one of the two projections 15 and in relief is slightly convex. The two projections 15 of the nut 7 have the same separation as the two annular projections 13 located on the interior wall of the ring 5. The separator 14 consists of a hollow cylindrical body with, at one of its ends, a slightly concave widened head 21 with a central bore, the other end opening into the expansion chamber 4. The separator 14 contains an ejector 6 of roughly the same length which is a component consisting of a cylindrical body 16, one end of which ends in a slightly conical widened head 17 with a diameter roughly equal to the internal diameter of the separator 14. The various components described hereinabove are arranged with respect to each other as follows:

#The separator 14 has the same axis of revolution as the nut 7 and is in contact with said nut 7 via its slightly concave widened head 21 which butts against the slightly convex end of the nut 7.

#The ejector 6 is housed in the separator 14 in such a way that its cylindrical body 16 passes through the widened head 21 of the said separator 14 so as to rest against the connecting screw 8 located in the segmented nut 7 and in such a way that its widened head 17 lies flush with the end of the separator 14 emerging into the gas expansion chamber 4.