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Needleless hypodermic jet injector

  • US 5,704,911 A
  • Filed: 12/08/1995
  • Issued: 01/06/1998
  • Est. Priority Date: 09/28/1992
  • Status: Expired due to Term
First Claim
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1. A spring actuated needleless hypodermic jet injection system comprising:

  • an ampule assembly comprising;

    a shell having a chamber for holding liquid medication between first and second ends of the shell;

    an orifice in the first end of the shell and communicating with the chamber through which liquid medication is drawn into and ejected out from the chamber; and

    a plunger assembly movable within the chamber for converting an applied force to a corresponding pressure applied to the liquid, the plunger assembly for drawing liquid medication into the chamber and for ejecting liquid medication out from the chamber;

    an injector for receiving and mounting the ampule assembly and for providing said applied force to move the plunger assembly, the injector comprising;

    a cylindrical housing having a front end, a back end, and defining a longitudinal channel therebetween, wherein the front end of the housing is open and configured to receive the second end of the ampule assembly;

    a piston mounted for sliding movement in the longitudinal channel, the piston for applying said force to the plunger assembly;

    a spring disposed within the channel and communicating with the piston, the spring for accumulating and storing a sufficient amount of energy when compressed to produce sufficient pressure to cause the liquid to leave the chamber via the orifice at such a velocity that it can be hypodermically injected at an injection site, wherein the energy is converted to said force by the piston when the spring is released;

    a trigger assembly coupled to the spring for manually releasing the stored energy;

    coupling means disposed in the open end of the injector housing for coupling the ampule assembly to the housing; and

    a safety interlock assembly, coupled between the trigger assembly and the coupling means, the safety interlock operatively responsive to the ampule assembly as being coupled to the injector housing, the safety interlock assembly preventing release of the stored energy by the trigger assembly unless an ampule assembly is coupled to the injector.

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