FR2342079A1 - Automatic intramuscular syringe - with preloaded springs for needle entry injection and retraction - Google Patents

Abstract

An automatic intramuscular syringe assembly comprises a piston type hypodermic syringe having a piston-advancing 'injection' spring which is loaded progressively as the piston is retracted to fill the syringe. The spring can be temporarily locked in this loaded position. The syringe body is engaged coaxially with tubular sleeve within which it is longitudinally movable to extend telescopically from the sleeve at one end so that the syringe needle is fully retracted within the sleeve at the other end. In this position an 'introduction' spring is fully loaded and temporarily locked, unlocking relieves the spring by allowing the syringe body to move further into the sleeve so that the needle projects from the far end of the sleeve. With the needle fully projected, the forward end of the syringe body rests on a thrust ring inside the casing. The thrust ring is locked in a spring-loaded condition which when released allows a 'retraction' spring to pull back the body so that the needle is inside the sleeve. Used for admin. of intramuscular injections. The action is fully automatic once the syringe has been charged and the three springs temporarily locked in loaded positions. Needle pressure and depth of entry are predetermined.