EP3328471A1 — A torsion spring driven injection device

USPTO Abstract

The invention relates to a torsion spring driven injection device for apportioning individually set doses of a liquid drug. The injection device has a needle cannula (35) for multiple uses and a cleaning chamber (56) for cleaning the tip of the needle cannula between subsequent injections. The cleaning chamber is filled with preservative containing liquid drug directly from the cartridge (30) in a filling sequence which is executed when the user initiates first use of the injection device. The sequence comprises the step of securing the piston rod guide in an inrotatable position and thereafter moving the cartridge in a proximal direction. Such axial movement of the cartridge without a similar movement of the plunger automatically pumps liquid drug from the cartridge and into the cleaning chamber via the lumen of the needle cannula.