Hypodermic syringe with selectively retractable needle

• Main Author: ROGER W HOECK
• Format: Patent
• Language: English
• Published: 07.03.2002
• Edition: 7
• Subjects: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROMTHE BODY; HUMAN NECESSITIES; HYGIENE; MEDICAL OR VETERINARY SCIENCE

A hypodermic syringe (10) with a selectively retractable needle (12) includes a barrel (14) having a proximal end (16) and a distal end (18) that defines a receiver (20) with a shoulder (22). The barrel has a hollow bore (24) therethrough and the receiver includes a plurality of inwardly projecting cams (26) distal to the shoulder. There is an elongate plunger (28) with a proximal end (30) and a distal end (32) sized to fit slidably within the bore of the barrel to define a chamber (34). There is a hub (36) with a flange (38) and a stem (40) that has a passageway (42) therethrough extending distally into the receiver. The stem has distal recesses (43) disposed to engage the projecting cams so that the hub is retained with the distal end of the stem in the receiver. The syringe includes a needle mounted in the passageway in the hub with the distal point (44) projecting distally and the fluid path communicates with the chamber. There is a clip (50) about the elongate plunger initially allowing movement of the plunger for drawing and expelling fluid. When sufficient distal force is applied to the plunger moving and rotating the hub, the clip engages the barrel permitting only proximal movement of the plunger. The syringe includes a spring (52) disposed about the stem compressed between the flange and the inward shoulder. When sufficient distal force is applied to the flange the hub is no longer retained. The spring urges a proximal movement into the barrel as the plunger is moved proximally.