| 主权项 |
1. A torsion spring based automatic injection device for expelling settable doses of a liquid drug comprising:
a housing assembly and a dose setting assembly being rotatable relatively to the housing assembly, a torsion spring encompassed between the housing assembly and the dose setting assembly such that the torsion spring is strained when rotating the dose setting assembly relatively to the housing assembly, and wherein the torsion spring is helically coiled having a longitudinal direction and a number of consecutive windings wherein a distal winding has a distal end and a proximal winding has a proximal end, the distal end and/or the proximal end being abruptly cut to form a flat end surface, each winding further having an outwardly pointing surface, and wherein at least one of the housing assembly or the dose setting assembly is at least partly made from a polymeric material and comprises a spring receiving arrangement comprising a first surface substantially parallel with the longitudinal direction of the helical torsion spring for abutting the distal end surface or the proximal end surface of the helical torsion spring and which spring receiving arrangement further comprises a second surface substantially parallel with the longitudinal direction of the helical torsion spring for supporting the outwardly pointing surface of the at least distal winding or the at least proximal winding, and wherein when the dose setting assembly are rotated relatively to the housing assembly to strain the torsion spring, the first surface of the spring receiving arrangement is pressed against the abruptly cut end surface of the torsion spring to strain the torsion spring thereby making the outwardly pointing surface of the at least distal winding and/or the at least proximal winding press against the second surface. |
