Patent ID: 8162887

Claim:
An injection device, comprising: a housing; a syringe coupled to a needle at one end, the syringe slideably mounted within the housing for movement between a first position relative to the housing in which the needle is shrouded by the housing and a second position relative to the housing in which the needle projects from the housing; a bung slideably mounted in the syringe and moveable to expel a liquid through the needle; a plunger comprising: an upper solid portion, a lower solid portion having one end operable to move the bung and to transmit an expulsion force thereto, and a projecting region comprising one or more flexible elbows on either side of a central void provided between the upper and lower solid portions of the plunger, the plunger having a first length when the projecting region is in a projecting position in which the one or more elbows project outwardly from the central void, the plunger having a second length greater than the first length when the projecting region is in a collapsed position in which the one or more elbows are collapsed inwardly toward the central void; and an actuating bias member provided at one end of the housing and operable to move the plunger toward another end of the housing.