Retractable syringe

摘要

A syringe including a barrel, a needle subassembly holder positioned in the barrel, and a needle subassembly positioned in the holder. The needle subassembly includes a needle hub releasably connected to the holder and a needle connected to the hub. Further, the syringe includes a piston slidably received by the barrel. The piston includes a piston body and a piston head having a releasable portion temporarily covering a hatchway. The piston also includes a valve positioned proximal of the hatchway and movable between blocking and passing positions. A user may push the piston distally beyond an injected position in which the piston head contacts the holder causing the holder to move distally and the hub to contact the barrel, causing the barrel to bow, thereby storing potential energy. When the potential energy reaches a threshold amount sufficient to overcome forces holding the hub in the holder, the barrel rebounds toward its un-bowed shape thereby propelling the needle hub and needle proximally past the releasable portion and the valve and into the piston body. The valve then automatically returns to the blocking position thereby ensuring that the needle subassembly does not move proximally out of the piston body.

主权项

1. A retractable-needle syringe assembly capable of a needle retraction operation, said assembly comprising:
a hollow barrel extending from an open proximal end to a distal end, said distal end defining a needle opening therein, said barrel further having an inner surface including a proximally-facing contact portion, a flexible portion of said distal end of the barrel being capable of bowing under force and storing potential energy for later use in said needle retraction operation; a needle subassembly holder positioned at least partially in said barrel adjacent said inner surface of said barrel; a needle subassembly including:
a needle hub releasably connected to said needle subassembly holder by holding forces, said needle hub having a maximum width and a distal end configured to engage said proximally-facing contact portion of the barrel; anda needle connected to said needle hub and extending through said needle opening during the pre-retraction use of the syringe; and a piston subassembly slidably disposable within said barrel through the open proximal end of the barrel, said piston subassembly including:
a piston body extending from a proximal end to a distal end and defining an inner region for receiving said needle subassembly during a retraction operation of said syringe assembly; anda piston head positioned at or adjacent said distal end of said piston body, said head extending from a periphery to an edge of an inner hatchway and said head also having a releasable portion temporarily covering an entirety of said hatchway and releasably connected to said edge of said hatchway, said hatchway having a width greater than said maximum width of said needle hub and said periphery of the head being configured to form a seal with said inner surface of the barrel when said piston subassembly is positioned within said barrel; wherein said flexible portion is configured to bend from an initial shape and thereby store potential energy as the needle hub is pressed against the proximally-facing contact portion of the barrel of the syringe assembly; and wherein said retractable-needle syringe assembly is configured to develop and release a level of potential energy during said needle retraction operation of the syringe assembly, during which said flexible portion is configured to bend until the potential energy stored in said barrel and any other parts of said needle syringe assembly combine to reach said developed amount of potential energy, and forces on said needle hub reach a threshold value sufficient to release said needle hub from said holder and such that said level of potential energy developed during said needle retraction operation of said syringe assembly is sufficient upon its release to propel said needle subassembly in a proximal direction through said hatchway and into said piston body, thus completing said needle retraction operation.