US Patent 9925344 Auto-injector

An auto-injector for administering a dose of a liquid medicament (M) is present having a tubular chassis telescopable in a tubular case, a carrier subassembly comprising a tubular carrier slidably arranged relative to the chassis inside the case, where the carrier is adapted to contain a syringe with a hollow injection needle. The injector also has a drive spring and a plunger for forwarding load of the drive spring to a stopper of the syringe, wherein the syringe is lockable for joint axial translation with the carrier. A control spring is arranged around the carrier for translating the carrier in a proximal direction (P) for insertion of the needle through the chassis into an injection site.