Patent ID: 8632507
Filing Date: 2014-01-21
Classification: A61M

Abstract:
1. An auto-injection device having a front end and a rear end and comprising: a rear housing and a container housing releasably connected to each other; a medicament container disposed within the container housing, wherein the container has a front opening with or for a delivery member for delivering a medicament therethrough and at least one movable stopper; a dose setting mechanism configured for setting and resetting a dose of the medicament; a drive nut releasably connected to the dose setting mechanism; a hollow plunger rod rotatably connected to the drive nut and arranged to have a front end of the hollow plunger rod in contact with the at least one movable stopper; an energy accumulating member having a first end connected to the dose setting mechanism and a second end connected to a fix point of the rear housing such that when the dose setting mechanism is operated to set the dose, the energy accumulating member accumulates energy in terms of at least one predetermined step; an activating mechanism releasably connected to the drive nut and configured for locking the drive nut against rotation when the dose is being set and for releasing the drive nut when the activating mechanism is manually activated such that the hollow plunger rod is linearly displaced toward the front end of the device by rotation of the drive nut due to the energy accumulated in the energy accumulating member and transferred through the dose setting mechanism; and a positioning mechanism operably connected to the hollow plunger rod and configured for locking the hollow plunger rod from being resiliently and axially displaced by rotation, wherein the positioning mechanism comprises a first locking nut rotationally locked but axially slidable surrounding the hollow plunger rod and arranged to co-operate with a flexible locking device arranged on the rear housing for locking the first locking nut from rotation, and a resilient member arranged inside the hollow plunger rod configured for allowing the hollow plunger rod to be resiliently and axially displaced when the first locking nut is unlocked.