Patent attributes
The invention refers to an auto-injector and to a method for operating it, the auto-injector comprising of a tubular chassis; a carrier subassembly comprising a tubular carrier slidably arranged in the chassis, the carrier containing a syringe with a hollow injection needle, a drive spring and a plunger for forwarding load of the drive spring to a stopper of the syringe; a wrap-over trigger sleeve arranged over the distal end (D) of the auto-injector; the trigger sleeve extending at least almost over the whole length of the auto-injector; a control spring arranged around the carrier; first interlock means for coupling a proximal end of the control spring to either the carrier for advancing it for needle insertion or to the chassis for needle retraction; second interlock means arranged for releasing the drive spring for injection; third interlock means arranged for coupling the chassis to the carrier for joint axial translation relative to the trigger sleeve; and fourth interlock means arranged for coupling a distal end of the control spring to either the carrier for needle retraction or to the trigger sleeve otherwise.
