Needleless hypodermic injection device

A jet injector comprising:

• an injector housing;
• a initiator valve within an initiator valve housing in the injector housing;
• a supply duct leading from a compressed gas source to the initiator valve housing;
• a reservoir connectable to the initiator valve through a regulation port;
• a poppet valve having a dart engageable towards and away from the regulation port, and a poppet body sealably engageable against a poppet seat;
• a drive piston slidably positioned in a drive chamber connectable to the reservoir through the poppet valve;
• a clamp piston slidable within a clamp piston chamber in the drive piston, the clamp piston chamber connected to the reservoir;
• an ampule releasably attached to the injector housing;
• a plunger slidably extending from the ampule at least partially into the drive piston;
• and
• clamp means adjacent the clamp piston engageable onto the plunger.

A needleless injection device comprising:

• a housing;
• a driver piston slidably contained within the housing;
• an ampule releasably attached to the housing;
• a plunger slidably extending from the ampule at least partially into the housing;
• an initiator valve for releasing compressed gas into a reservoir within the housing;
• a poppet valve for controlling flow of compressed gas from the reservoir to the driver piston;
• a clamp piston within the housing and having ramp surfaces;
• a pair of opposing clamp jaws slidable on the ramp surfaces;
• and
• clamp jaw biasing means for biasing the clamp jaws apart.

A needleless injection device comprising:

• a housing;
• a driver piston slidably contained within the housing;
• an ampule releasably attached to the housing;
• a plunger slidably extending from the ampule at least partially into the housing:,
• a clamp piston within the housing and having ramp surfaces;
• a pair of opposing clamp jaws slidable on the ramp surfaces;
• clamp jaw biasing means for biasing the clamp jaws apart;
• and
• a regulation valve attached to the poppet valve for regulating flow into a reservoir within the housing.

A needleless injection device comprising:

• a housing;
• a driver piston slidably contained within the housing;
• an ampule releasably attached to the housing;
• a plunger slidably extending from the ampule at least partially into the housing;
• a clamp piston within the housing and having ramp surfaces;
• a pair of opposing clamp jaws slidable on the ramp surfaces;
• clamp jaw biasing means for biasing the clamp jaws apart;
• a poppet valve for controlling flow of compressed gas from a reservoir within the housing to the driver piston, the poppet valve including:
• a poppet body having a sealing rim, a conical poppet seat and a spring for biasing the sealing rim of the poppet body against the poppet seat, with the poppet seat and poppet body forming at least in part, a poppet annulus.

A method of needleless injection comprising the steps of

• installing an ampule and plunger containing an injectant into an injector;
• releasing compressed gas into a reservoir and using it to mechanically engage a driver piston onto the plunger;
• releasing compressed gas from the reservoir when the gas pressure reaches a cracking pressure to act on the driver piston;
• and
• driving the plunger into the ampule substantially using compressed gas released from the reservoir.