Patent ID: 8123718
Filing Date: 2012-02-28
Classification: A61M

Abstract:
1. A needle-free injection device for delivering a medicament under pressure from a dosing reservoir through an outlet orifice for administration to an animal or human, of the type comprising a plunger slidably received in said dosing reservoir and movable in a forward direction for expelling said medicament through said orifice, said injection device comprising an actuating device and said actuating device comprising: (a) a gas tight chamber; (b) a piston and rod assembly slidably received in said chamber and movable between a forward position and a rearward position; (c) a gas charge in said chamber for urging said piston and rod assembly to said forward position; (d) a charging mechanism for moving said piston and rod assembly against said gas charge into said rearward position, said charging mechanism comprising a threaded shaft threadingly engaged with nut member that is operatively associated with said piston and rod assembly and moveable along a length of the threaded shaft when said threaded shaft is rotated; and (e) a trigger for releasably retaining said piston and rod assembly in said rearward position, whereby activating said trigger causes said piston and rod assembly to be released for movement by said gas charge to said forward position so as to impact said plunger directly or indirectly with a force sufficient to cause said plunger to move in said forward direction to expel said medicament through said outlet and whereby said gas tight chamber is adapted to minimize or prevent the escape of said gas charge so as to maintain said gas charge is a pressurized state.