Locking and blocking system for discardable or disposable syringe

摘要

Single use discardable and auto-locking syringe comprising a barrel, a plunger and a locking means to prevent a subsequent aspiration. The locking means comprising radially expanding elastic claws connected to the plunger and being compressed together by a retaining ring in order to avoid their contact with the inner wall of the barrel. During injection stroke the friction between the retaining ring and the inner side wall of the barrel is higher than the one between the retainer ring and the claws. Consequently the retaining ring remains stationary at the proximal end of the barrel the claws disengage from the retaining ring and spread radially due to their elasticity to engage the inner side wall of the barrel and inhibit retracting plunger rod so as to prevent reloading of the syringe. Moreover, if forced retraction of the plunger is attempted in order to reload the syringe the claws will perforate the syringe barrel due to their sharpened ends. The production costs of the locking means are very low.