Improvements relating to automatic injection devices

摘要

An injection device comprises a syringe 1 extendible against the bias of spring 9 from a retracted position, Fig 1, in a housing 2 to a projecting injecting position, Fig 3. A spring 8 biased plunger 7 has collapsible elbows 10 which, when the plunger is released, initially engage the end of the syringe to drive it to the projecting position, whereupon arresting of the syringe movement causes the elbows to collapse inside the syringe body 3 to allow the plunger 7 to engage and drive the bung 4 to compress liquid within the syringe and cause expulsion of the liquid through the needle 5 of the syringe.