Spring powered needle-free injection system

A needle-free injection device, comprising:

• a housing;
• an elongate shaft;
• a first spring stop member;
• a second spring stop member, where one of the first and second spring stop members is threadably engaged with a threaded portion of the shaft;
• a spring disposed between the first and second spring stop members;
• and
• a plunger secured to the second spring stop member and slidably disposed within a fluid chamber, the plunger being operable to be retracted to draw injectable fluid into the fluid chamber through an injection orifice, and advanced within the fluid chamber to cause the injectable fluid to be forcibly ejected out through the injection orifice,
• where the injection device is configured so that, when the injection device is in an unarmed condition, and upon rotation of the shaft in a first direction, the first and second spring stop members are brought closer together to compress the spring,
• where the injection device includes a latching mechanism configured to latch the first and second spring stop members together upon full compression of the spring, so as to maintain the spring in a fully compressed state between the first and second spring stop members,
• where the latching mechanism includes a latch member that is pivotally connected to one of the first and second spring stop member and configured to move through the housing when the one of the first and second spring stop member moves through the housing, and
• where, when the first and second spring stop members are latched together, the first and second spring stop members are configured for movement through the housing while maintaining the spring in a fully compressed state.