Patent ID: 6474219
Filing Date: 2002-11-05
Classification: A61M,B05C

Abstract:
A flexible piston rod for an injection device, having the form of a helical spring made up from a number of narrowly adjacent turns of windings providing an external thread for moving a piston forward inside a cartridge containing a liquid, said flexible piston rod transmitting a movement from a piston rod drive to a longitudinal displacement of said piston, said flexible piston rod having a distal end abutting said piston inside said cartridge and a proximal end being deflected away from the axis of said cartridge, said piston rod drive including a nut element having an internal thread engaging said external thread of said flexible piston rod and which nut element is locked against longitudinal displacement and forcedly rotated, characterized in that said flexible piston rod has means locking said flexible piston rod against rotation.