Patent ID: 8708973

Claim:
A medical delivery device, comprising: a housing; a medicament container arranged to be placed in the housing; a stopper movable within the container; a medicament dispensing device attachable to the housing and the container through which medicament can be expelled, wherein the medicament dispensing device is an injection needle; a power unit, comprising a cover, a single volute spring arranged within the cover, and a pressure member having a pressure pad in contact with the stopper, a guide rod extending into the volute spring and an annular ledge in contact with the edges of the volute spring; an activation mechanism mechanically connected to the cover and to the housing; and a spring locking mechanism mechanically connected to the activation mechanism, wherein the spring locking mechanism comprises a deformable ring-shaped member having an inner diameter larger than the annular ledge, such that the ring-shaped member presents an oval shape when it is in contact with the annular ledge for locking the volute spring in a tensioned state.