AUTOMATIC DEVICE FOR INJECTIONS Russian patent published in 2015 - IPC A61M5/20 

FIELD: medicine.

SUBSTANCE: invention relates to medical equipment, namely to automatic injectors. Automatic injector contains case, made with possibility of receiving syringe, installed with possibility of sliding travel between retracted position and projected, working position, in which needle projects from case, and drive mechanism, released from state with accumulated energy for moving syringe forward, to working position for forcing out dose. Drive mechanism contains plunger, made with possibility of bringing in motion piston, intermediate drive component, first drive compression spring, installed between intermediate drive component and case or component connected with it and pressing intermediate drive component forward, and second compression spring, installed between intermediate drive component and plunger and pressing plunger forward. Intermediate drive component contains, in fact, cylindrical case, providing presence of internal cylindrical support surface to restrict second spring from outside and external cylindrical support surface to restrict first spring from inside, and has internal cylindrical cavity for introduction into it of posterior end of second compression spring; immediately after release of drive mechanism second spring after expansion turns up on at least main part of its length, surrounded by said cylindrical cavity and internal channel of syringe case or at least one of said volumes, and second spring is selected such that springing effort, which it applies, being in fact in completely compressed state, is smaller than effort, required for overcoming static friction between piston and syringe case, but larger than effort, required for supporting piston movement after static friction is overcome by residual effort, created by first spring, when syringe is in its working position.

EFFECT: application of invention makes it possible for intermediate drive component and plunger to perform relative movement immediately after release of drive mechanism on condition of compact size of automatic injector.

13 cl, 15 dwg