Patent ID: 7935088
Filing Date: 2011-05-03
Classification: A61M

Abstract:
1. A drive mechanism for a drug delivery device comprising: an internal housing having a helical thread surrounded by a main housing; a dose dial sleeve having a helical thread engaged with the helical thread of the internal housing, the dose dial sleeve positioned between the internal housing and the main housing; a piston rod, a drive sleeve releasably connected to the dose dial sleeve via a clutch mechanism that is located between the dose dial sleeve and the drive sleeve, wherein: when the dose dial sleeve and the drive sleeve are coupled via the clutch mechanism, both are allowed to rotate with respect to the internal housing and with respect to the piston rod, and when the dose dial sleeve and the drive sleeve are decoupled, rotation of the dose dial sleeve with respect to the internal housing is allowed, rotation of the drive sleeve with respect to the internal housing is not allowed, and axial movement of the drive sleeve with respect to the internal housing is allowed so that a force is transferred in a longitudinal direction to drive the piston rod of the drug delivery device.