Patent ID: 8668670

Claim:
An injection device, comprising: a housing; a syringe slideably mounted within the housing for movement between a shrouded retracted position relative to the housing and an extended injecting position relative to the housing; a movable bung slideably mounted in the syringe and moveable to expel a liquid dose through a needle couplable at a distal end of the syringe; a plunger having a distal end operable to move the bung and to transmit an expulsion force thereto, the plunger being in the form of a rod including: an upper solid portion having a circular cross-sectional profile, a lower solid portion having a distal end operable to move the bung and to transmit an expulsion force thereto, the lower solid portion having a first circular circumference, and a projecting portion comprising two flexible elbows on either side of a central void extending along a central axis of the plunger between the upper and lower solid portions, wherein the flexible elbows project outwardly from the central void when the projecting portion is in a first projecting position, wherein the flexible elbows are inwardly collapsible toward the central void when the projecting portion is in a second collapsed position; and an actuating bias spring operable to drive the plunger to move the syringe from the shrouded retracted position relative to the housing to the extended injecting position relative to the housing, and to move the plunger forwardly within the syringe to act upon the bung to transmit the expulsion force thereto in order to expel the liquid dose from the syringe through the needle.