Dose setting mechanism

Abstract

An injection device comprises a housing having a longitudinal axis, an axially-depressible dose button (), a dose indicator (), a dose setting mechanism operatively coupled to said dose indicator and capable of setting a dose to be ejected from the injection device and spring capable of storing energy necessary for ejecting the dose from the injection device. The spring () is coupled to the dose setting mechanism such that a charging force can be transferred from the dose setting mechanism to the spring to increase the energy stored by the spring. The dose setting mechanism comprises an assembly of three components, including: •a ratchet ring () rotationally and axially locked with respect to said housing, the ratchet ring including a ratchet component; •a drive plate () including a first set of splines forming a ratchet arrangement with said ratchet component; and•a dose selector () capable of being rotated about said longitudinal axis with respect to said housing to set the dose and including splines for disengaging said ratchet arrangement. The ratchet component is capable of interacting with both the splines on the dose selector and the splines on the drive plate.