| abstract |
Handheld drug injection device ( 10 ) for setting and dispensing of a dose of a medicament, having a housing ( 20 ) extending in an axial direction ( 1, 2 ) and a dose setting and drive mechanism ( 3 ) comprising: —a rotatable dose setting member ( 50 ) in a sidewall of the housing and engaging two dose indicating wheels ( 54,56 ), —a drive member ( 70 ) axially displaceable relative to a drive spindle ( 80 ) and the housing against the action of a spring element ( 78 ) during dose setting and having a sleeve-shaped part ( 72 ) being threadedly engaged with the drive spindle ( 80 ) to form a spindle gear, and having a rack portion ( 71 ) engaged with a gear wheel ( 58 ) of the dose setting member, —the drive spindle ( 80 ) being linked on its proximal end to a ratchet mechanism ( 140,150 ) which is releasable via an axially shiftable trigger button ( 40 ) for dose dispensing, and on its distal end via a pinion ( 86 ) to a —drive sleeve ( 90 ), the latter being axially shiftable to form a clutch for engagement with —a threaded piston rod ( 120 ), which engages a piston ( 14 ) of a cartridge ( 12 ) to displace the piston ( 14 ) in a distal axial direction ( 1 ), the trigger button ( 40 ) releasing the ratchet holding the drive spindle ( 80 ) to free it for rotation, and closing the clutch between drive sleeve ( 90 ) and piston rod ( 120 ), such that the drive spring ( 78 ) can push the drive member ( 70 ) forward, thereby rotating the spindle ( 80 ), which in turn rotates the drive sleeve ( 90 ), which in turn produces spiral forward movement of the piston rod ( 120 ). A dose limiter element ( 130 ) is also included between piston rod and coaxial drive sleeve. |