Disposable medical syringe with retractable needle. - has needle is attached to an elastic block which is adapted to engage the end of the piston at the end of its stroke, and is withdrawn inside the cylinder as the piston is retracted

摘要

A medical syringe (10) comprises: (a) a cylinder (11), a piston (20) and a needle-carrying block (30), wherein (b) said cylinder (11) is provided with annular grooves (12,13) at the bottom end, and two more such grooves (17,18) near the open end thereof. A hole (14) is centrally disposed in the bottom of the cylinder, and (c) said block (30) is made from an elastomeric material, is a close fit within the internal dia. of said cylinder (11), is provided with two annular ridges (25,26) adapted to engage grooves (12,13 and 17,18), and has an axial beak-shaped protruberance (35) to which a needle (40) is attached, said needle and protruberance being free to pass through hole (14). The block (30) also has a central discoid chamber (37) adapted to engage and retain (d) said piston (20), which has a first head (21) with a second smaller head (22) connected thereto by a shank (23), said second head being sized and shaped to fit into said discoid chamber (37). Holes (27) and channels (28) in said smaller head (22) permit the passage of liquid (36).