Patent ID: 9072836
Filing Date: 2015-07-07
Classification: A61M,F16H,Y10T

Abstract:
1. A drive mechanism for a drug delivery device, comprising: a lead screw, a lead screw nut and a drive member, aligned with an axis defining an axial direction and an opposite axial direction, a coupling between the lead screw and the lead screw nut allowing a helical movement of the lead screw with respect to the lead screw nut at least in the axial direction, the lead screw being coupled with the drive member, the coupling of the lead screw with the drive member generating a helical movement of the lead screw with respect to the drive member when the drive member is moved in the axial direction with respect to the lead screw, and the coupling of the lead screw with the drive member being overridden to prevent a helical movement of the lead screw with respect to the drive member when the drive member is moved in the opposite axial direction with respect to the lead screw, a dispense stop feature of the lead screw nut, and a dispense stop feature of the drive member, the dispense stop features interacting and thereby preventing the generation of the helical movement of the lead screw when the drive member approaches a specified end position of dispense, wherein the dispense stop features guide the drive member with respect to the lead screw nut in a helical movement having the same pitch as the helical movement of the lead screw with respect to the drive member.