Injection device with a spring for a needle protecting sleeve

Abstract

An injection device including a housing, a needle guard sleeve displaceable relative to the housing, and a spring coupled to the guard sleeve such that the guard sleeve can be moved by the spring distally from a proximal position to an end position, the spring also being coupled to a forward drive element displaceable relative to the housing in a drive direction wherein the spring is tensioned upon a movement of the forward drive element in the forward drive direction.

What is claimed is: 
     
         1 . An injection device comprising:
 a) a housing configured to enclose a product container;   b) a needle protecting sleeve comprising a locking cam, wherein movement of the locking cam in a distal direction beyond a locking tongue of the delivery device causes the locking tongue to spring radially to block the needle protecting sleeve in an end position against moving in a proximal direction;   c) a piston rod configured to shift a piston in the distal direction;   d) a delivery spring acting on the piston rod, wherein the piston rod is at least partially hollow and sleeve-shaped and encloses the delivery spring in a biased state of the delivery spring;   e) a restoring spring for shifting the needle protecting sleeve in the distal direction from a proximal position to the end position; and   f) a releasing member with a protrusion mounted on a distally oriented elastic arm and directed radially inward to engage an outer surface of the piston rod in an engagement to prevent the piston rod from moving in the distal direction, wherein the releasing member is prevented from disengaging from the engagement with the piston rod by a radially inward directed surface of a supporting element preventing the releasing member from moving radially outward.