Patent ID: 6017325
Filing Date: 2000-01-25
Classification: A61M

Abstract:
A disposable syringe with an automatically retractable hypodermic needle, comprising:an outer tube having an internal diameter and a forward housing defining an inner front wall face and a coupling end, a piston in the outer tube and having a hollow tube shank, at least a posterior section of the shank having a diameter less than the internal diameter of the outer tube, and an annular working face movable toward the inner front wall face of the outer tube,a needle holder connected to the coupling end of the outer tube, the needle holder having a distal guide conduit,a hypodermic needle in the distal guide conduit of the needle holder and having a coupling nipple wedged in a posterior axial portion of the needle holder,an annular elastomer washer housed between the inner face of the front wall of the outer tube and the working face of the piston;a plug in the annular working face of the piston, the plug having a perimetral projection caught posterially by small internal projections in the hollow tube shank and having a forward capturing tip of frustoconical shape matching the coupling nipple of the needle, the hollow tube shank having at least one orifice providing fluid communication between the plug and the hollow shank exterior, andelastic means linking the plug and the piston and placed in tension in a position of maximum compression of the annular elastomer washer.