Drive Mechanism for a Drug Delivery Device

Abstract

A drive mechanism for a drug delivery device having a rotationally fixed plunger rod driven by a lead screw. The lead screw engages a free lock which is coupled to a release knob. A dose setting dial cooperates with an inner cylinder using a clutch to establish the axial movement of the plunger rod during dose setting and dispensing.

1 - 14 . (canceled) 
     
     
         15 . A drive mechanism for use in a drug delivery device, the drive mechanism comprising:
 a housing having a proximal end, a distal end, and an internal thread;   a dose setting dial threadedly engaged with the internal thread and configured to simultaneously rotate and traverse axially towards the proximal end during dose setting and to simultaneously rotate and traverse axially towards the distal end during dose dispensing;   a plunger rod rotatably fixed relative to the housing during both dose setting and dose dispensing, the plunger rod having a hollow portion and a distal end configured to abut and move a cartridge piston during dose dispensing;   a lead screw threadedly engaged with the threaded hollow portion of the plunger rod such that the lead screw can rotate relative to the plunger rod;   an inner cylinder engaged with and positioned within the dose setting dial such that axial movement of the dose setting dial causes simultaneous axial movement of the inner cylinder, where the inner cylinder is rotatably fixed relative to the lead screw;   a clutch which releasably connects the dose setting dial and the inner cylinder; and   a plunger rod holder rotatably fixed relative to the housing and keyed coupled to the plunger rod to prevent the plunger rod from moving towards the proximal end during dose setting, wherein the plunger rod holder allows the plunger rod to move axially towards the distal end during dose dispensing.   
     
     
         16 . The drive mechanism according to  claim 15 , further comprising a cylindrical rotating knob rotatably fixed relative to the dose setting dial. 
     
     
         17 . The drive mechanism according to  claim 15 , further comprising a release knob configured to move axially and distally during dose dispensing to cause the dose setting dial and the inner cylinder to simultaneously move distally. 
     
     
         18 . The drive mechanism according to  claim 15 , wherein the hollow portion of the plunger rod is cylindrical. 
     
     
         19 . The drive mechanism according to  claim 15 , wherein the housing comprises a display window. 
     
     
         20 . The drive mechanism according to  claim 19 , wherein an outer surface of the dose setting dial comprises numerical values that are visible through the display window to indicate a set dose. 
     
     
         21 . The drive mechanism according to  claim 20 , wherein the display window is an aperture defined by the housing. 
     
     
         22 . A drug delivery device comprising:
 a cartridge holder;   a housing having a proximal end, a distal end, and an internal thread;   a dose setting dial threadedly engaged with the internal thread and configured to simultaneously rotate and traverse axially towards the proximal end during dose setting and to simultaneously rotate and traverse axially towards the distal end during dose dispensing;   a plunger rod rotatably fixed relative to the housing during both dose setting and dose dispensing, the plunger rod having a hollow portion and a distal end configured to abut and move a cartridge piston of a cartridge disposed in the cartridge holder during dose dispensing;   a lead screw threadedly engaged with the threaded hollow portion of the plunger rod such that the lead screw can rotate relative to the plunger rod;   an inner cylinder engaged with and positioned within the dose setting dial such that axial movement of the dose setting dial causes simultaneous axial movement of the inner cylinder, where the inner cylinder is rotatably fixed relative to the lead screw;   a clutch which releasably connects the dose setting dial and the inner cylinder; and   a plunger rod holder rotatably fixed relative to the housing and coupled to the plunger rod to prevent the plunger rod from moving towards the proximal end during dose setting, wherein the plunger rod holder allows the plunger rod to move axially towards the distal end during dose dispensing.   
     
     
         23 . The drug delivery device according to  claim 22 , further comprising a cylindrical rotating knob rotatably fixed relative to the dose setting dial. 
     
     
         24 . The drug delivery device according to  claim 22 , further comprising a release knob configured to move axially and distally during dose dispensing to cause the dose setting dial and the inner cylinder to simultaneously move distally. 
     
     
         25 . The drug delivery device according to  claim 22 , further comprising the cartridge disposed in the cartridge holder. 
     
     
         26 . The drug delivery device according to  claim 25 , wherein the cartridge contains a medicament. 
     
     
         27 . The drug delivery device according to  claim 26 , wherein the medicament comprises insulin, heparin, or a derivative or analogue thereof. 
     
     
         28 . The drug delivery device according to  claim 22 , wherein the hollow portion of the plunger rod is cylindrical. 
     
     
         29 . The drug delivery device according to  claim 22 , wherein the housing comprises a display window. 
     
     
         30 . The drug delivery device according to  claim 29 , wherein an outer surface of the dose setting dial comprises numerical values that are visible through the display window to indicate a set dose. 
     
     
         31 . The drug delivery device according to  claim 30 , wherein the display window is an aperture defined by the housing.