AUTOMATIC INJECTION DEVICES

摘要

An injection device comprises a syringe extendible against a spring bias from a retracted position in a housing to a projecting injecting position. A spring biased plunger has collapsible elbows 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 to allow the plunger to engage and drive the bung.

主权项

1. An injection device for causing a dose of liquid to be ejected from the needle at one end of a syringe (1) located within a housing (2) of the device, the syringe being movable by a plunger (7), upon release of an actuating bias member (8) at one end of the housing (2), to move the syringe (1), from a first position wherein the needle (5) is shrouded by the housing (2), to a second position wherein the needle projects from the other end of the housing, the plunger being in the form of a rod with a longitudinally centrally located flexible projecting portion which, prior to release of said actuating bias member, is situated beyond the other end (6) of the syringe (1), such that a primary movement of the plunger (7), under the bias of the actuating bias member (8), will cause the projecting portion (10) to bear against the other end (6) of the syringe such that the syringe is moved from said first to said second position, whereupon arresting of further movement of the syringe, results in the flexible portion (10) collapsing inwardly so that it enters the syringe, thus enabling the plunger (7) to move by a secondary movement, within the syringe, into contact with and to act upon a plug (4) to compress the liquid within the syringe and cause expression of the liquid through the syringe needle (5).