BREECH LOADED SYRINGE WITH DEFORMABLE PISTON

• US 3,834,387 A
• Filed: 08/10/1972
• Issued: 09/10/1974
• Est. Priority Date: 08/10/1972
• Status: Expired due to Term

• Current Assignee: Sherwood Medical Company (Medtronic Plc)
• Original Assignee: Alexander M. Brown
• Inventors: Brown, Alexander M.
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): McGowan, J. C.
• Application Number:
  US05/279,614
• Time in Patent Office: 761 Days
• Field of Search: 128/218P,218PA,219,215,216,220,234,218R 141/27
• US Class Current: 604/125
• CPC Class Codes: A61M 2005/3123 having air entrapping or venting means, e.g. purging channels in pistons
• CPC Class Codes: A61M 5/1782 Devices aiding filling of syringes in situ combination of a vial and a syringe for transferring or mixing their contents A61J1/2096, filling of medical containers in general B65B3/003
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding

Abstract

A plunger assembly for a syringe adapted to be filled through the breech end of the syringe barrel including a piston rod having a piston on the distal end thereof for insertion into the breech end of the barrel, and a piston control member slidable in an opening in the piston rod and engageable with the interior of the piston to stretch the piston and provide a vent passage around the piston during movement of the piston and piston rod in the barrel. Medicament is introduced into the syringe barrel to the desired level and the plunger rod and control member are moved relative to each other to stretch and deform the piston. The deformed piston is then moved in the syringe barrel to a desired position and released by the control member into sealing engagement with the barrel.

Claims

1. A syringe comprising a barrel defining a fluid chamber having an opening at the rearward end thereof for receiving a medicament, a plunger assembly axially movable in said chamber and including a hollow resilient piston disposed in said chamber and having an opening at the rearward end thereof, a forward end wall, and an annular side wall portion with peripheral sealing means thereon for sealing and sliding engagement with said chamber, and a piston rod extending into said hollow piston and connected to said rearward end to manipulate said piston in said chamber during operational use of the syringe, said piston rod extending into said piston through said opening and having an axial bore extending therethrough from the forward end to the rearward end, and piston control means extending through said bore and having a forward end engageable with the interior of said forward end wall of said piston, said control means including a control rod portion disposed in and axially slideable in said bore along a straight line to a forward position in response to applied forces thereon to move said forward end wall of said piston forwardly relative to the rearward end of said piston to stretch said piston and reduce the diameter of said annular side wall portion to thereby move at least a portion of said peripheral sealing means radially inwardly from said chamber to provide a fluid bypass passage between the forward and rearward ends of said piston for venting a portion of said chamber forward of said piston during movement of said piston in said chamber, said control rod portion being axially slideable in a rearward direction relative to said forward end wall to remove said control means from said piston rod and to release said stretched piston and allow the resiliency thereof to return said forward end wall rearwardly and said peripheral sealing portion radially outwardly into sealing engagement with said chamber, said piston being movable thereafter in said chamber in response to applied forces on said piston rod during operational use of the syringe.

2. The syringe of claim 1 wherein the length of said control means is greater than the length of said piston rod and has a rearward end rearwardly of said piston rod for receiving said applied forces thereon.

3. The syringe of claim 2 wherein said barrel, said piston rod, and said control means each have laterally extending flange means thereon at the rearward ends thereof for facilitating manual actuation thereof.

4. The syringe of claim 3 wherein said piston rod has a head portion at its forward end disposed within said piston and has an annular groove adjacent the rearward end of said head portion for receiving the rearward end portion of said pistOn to secure said piston to said piston rod, said annular walls being stretched in an axial direction relative to said head to provide said fluid bypass passage.