Needle-less injector and method of fluid delivery
A needle-less injector device for delivering a dose of fluid intradermally, subcutaneously or intramuscularly to an animal or human. The device includes an inner housing having opposed ends. A syringe is disposed in one end of the inner housing. The syringe includes a nozzle for delivering a dose of fluid held within the syringe. A plunger is movably disposed within the syringe. A spring powered hammer is movably disposed within the inner housing. The hammer cooperates with the plunger to drive the dose of medicament from the nozzle. An injection delivery spring for powering the hammer is positioned and compressed between the other end of the inner housing and the spring powered hammer. An outer housing slideably supports the inner housing. A skin tensioning spring is mounted between the inner housing and the outer housing, the skin tensioning spring biasing the nozzle of the syringe against the animal or human. A trigger mechanism is disposed in the outer housing, the trigger mechanism cooperating with the spring powered hammer to release the injection delivery spring, wherein the size of the injection delivery spring and the length of the hammer dictate the amount of dose delivered and whether the dose is delivered intradermally, subcutaneously or intramuscularly to an animal or human.
1. A needle-less injector device comprising:
an inner housing;
a trigger;
an outer housing supporting the inner housing and trigger such that the inner housing is axially movable within the outer housing between a safe position where actuation of the trigger will not cause an injection and a firing position where actuation of the trigger will cause an injection; and
a tensioning spring between the inner housing and the outer housing, the tensioning spring biasing the inner housing towards the safe position; wherein the tensioning spring comprises an adjustable tensioning spring.
2. The needle-less injector device of claim 1 , further comprising a threaded plug associated with the adjustable tensioning spring configured to screw against the adjustable tensioning spring to pre-tension the adjustable tensioning spring.
3. The needle-less injector device of claim 1 , wherein the tensioning spring is selected to comprise a predetermined tensioning force during assembly of the needle-less injector device.
4. The needle-less injector device of claim 3 , further comprising indicia associated with the outer housing to inform a user of the predetermined tensioning force.
5. The needle-less injector device of claim 4 , wherein the indicia on the outer housing comprises color coding to inform a user of the predetermined tensioning force.