PEN-TYPE DRUG INJECTION DEVICE WITH DOSE SETTING AND RE-SETTING MECHANISM

摘要

The present invention relates to a pen type drug injection device (1; 101) comprising a housing (4, 5; 104, 105), a dose dial member (6; 106), a torsion spring (12; 112) fixed between the housing and the dial member such that energy is accumulated in the torsion spring upon rotation of the dial member relative to the housing, a drive member (8; 108) engaging a lead screw (9; 109), a first clutch (18; 118) rotationally coupling the drive member (8; 108) and the housing in a coupled state and allowing relative rotation between the drive member and the housing in a de-coupled state, and a second clutch (19; 119) rotationally coupling the drive member and the dial member in a coupled state and allowing relative clockwise and anti-clockwise rotation between the drive member and the dial member in a de-coupled state. The second clutch comprises a ratchet clicker with teeth (19a, 19b; 119a, 119b) having in the clockwise and the anti-clockwise direction different ramped tooth angles such that the teeth are allowed to override each other in the de-coupled state of the second clutch with a different resistance in the clockwise and the anti-clockwise direction, such that a dose can be set and also corrected by the user thereby tensioning respectively relaxing the torsion spring.