Drive mechanism for an injection device

摘要

A drive mechanism for an injection device is disclosed in wich piston means 306 are selectively driven to expel medicament from within a medicament cartridge 40. A drive mechanism for controlling the movement of the piston means is described comprising a housing 302, a shuttle 300 located for movement within the housing 302 along a longitudinal axis between a first position and a second position, and drive means to move the shuttle 300 within the housing 302. A gear component 304 is located within the housing 302 for rotation about the longitudinal axis and associated with the piston means 306, movement of the shuttle 300 between each of the first and the second positions causing movement of the piston means 306.