US 4,869,720 AGranted

Hypodermic syringe assembly

AssigneeE-Z-EM, Inc.

InventorMilton P. Chernack

Life of this patent

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Abstract

A hypodermic syringe assembly includes an elongated container and a cup shape molded piston longitudinal movable in the container. The container has a sidewall, a needle receiving end, and a piston receiving end which terminates in a rim. The piston has an open rear end with at least three equally spaced integral hinged tabs therearound. The piston has a first position partially inserted at the container rear where the tabs extend radially outward from the container adjacent its rear end. The piston in this position can receive a disc shaped plunger head. The piston has a second position fully inserted in the container where the tabs are rotated about their hinges and extend radially inward within the container. In this position the piston tabs hold a disc shaped plunger head within the piston. The piston has a third position partially extended out of the rim of the dispensing container. In this position the tabs are rotated about the hinges and extend radially outward sufficient to permit the plunger head to withdraw from the piston. The sidewall of the dispensing container holds the tabs in a radially inward position in all fully inserted longitudinal positions of the piston.

A hypodermic syringe assembly comprising:

an elongate dispensing container having a central elongate axis and a sidewall radially outward of said axis,
said container having a needle receiving forward end and a piston receiving rearward end terminating in a rim,
a cup shaped molded plastic piston mounted for longitudinal motion in said container, said piston having an open rear end adapted to receive a disc shaped plunger head, and a closed front end,
said piston having a sidewall in sealing relationship with the sidewall of said dispensing container,
said piston having at least three integral hinged holding tabs substantially equally spaced around the perimeter of the rear end of said sidewall of said piston,
said piston having a first position partially inserted in said container at the rear of said dispensing container wherein each of said tabs extends radially outward from said container adjacent to the back end of said container,
said piston in said first position capable of receiving a plunger head,
said piston having a second position fully inserted in said container wherein said tabs are rotated about said hinges and extend radially inward within said container,
said tabs of said piston in said second position capable of holding a plunger head within said piston,
said piston having a third position partially extended out of said rim of said dispensing container wherein each of said tabs are rotated about said hinges to extend radially outward sufficiently to permit a plunger head to withdraw from said piston,
said sidewall of said dispensing container holding said tabs in said radially inward position in all fully inserted longitudinal positions of said piston,
whereby a plunger head forced longitudinally forward against said piston in said first position will seat within said piston and push said piston forward causing said hinged tabs to pivot about the rear end of said container sidewall and rotate on their integral hinges to hold the plunger head and permit full insertion of the piston.

9 more elements

Facts

Application

07/190,646Filed 5 May 1988

Granted

26 Sep 1989

Term ends

Not estimatedThe source records don’t support an estimate.

Classification4 codes

A61M 5/31511
Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing…:…
A61M 5/31513
Piston or piston-rod constructions, e.g. connection of piston with piston-rod: piston constructions to improve sealing or sliding
A61M 5/31515
Piston or piston-rod constructions, e.g. connection of piston with piston-rod: connection of piston with piston rod
A61M
Devices for delivering substances into the body

Abstract

Claims14