Patent ID: 8939945
Filing Date: 2015-01-27
Classification: A61M

Abstract:
1. A drive mechanism for a drug delivery device, comprising: a body having a distal end and a proximal end, which are spaced apart in the direction of an axis, a lead screw arranged within the body along the axis, the lead screw being movable relatively to the body, a lead screw nut, the lead screw comprising a screw thread and the lead screw nut comprising a drive feature coupling the lead screw and the lead screw nut, so that the lead screw is helically rotatable in the lead screw nut, the lead screw comprising a stop features interfering with a rotation of the lead screw and the lead screw nut relative to one another when a force is applied to the lead screw in the proximal direction, the body comprising a guide that restricts a movement of the lead screw nut, the lead screw nut comprising a surface area facing the guide, the surface area comprising a slope varying around the axis, and the screw thread, the slope, and the guide interacting in such a manner that the lead screw nut rotates in a first direction when a force is applied to the lead screw in the proximal direction.