Patent ID: 9572927
Date: 2017-02-21
CPC Classifications: A61M

Claim:
1. A medicament delivery device comprising: a housing; a telescopic piston rod assembly for driving a bung of a medicament container, the telescopic piston rod assembly comprising a plunger for driving the bung, a cylindrical input drive, and an elongate key member positioned within the plunger, wherein the plunger comprises an external screw thread, wherein the cylindrical input drive comprises a distal end and a proximal end, and wherein the proximal end of the cylindrical input drive comprises a drive gear; and a drive mechanism for the telescopic piston rod assembly, the drive mechanism comprising a rotatable transfer drive configured to be operatively coupled to the cylindrical input drive for rotating the cylindrical input drive, wherein an outer surface of the rotatable transfer drive comprises an axially extending gear, wherein the cylindrical input drive is configured to move axially along the outer surface of the rotatable transfer drive as the cylindrical input drive moves telescopically relative to the plunger, wherein the external screw thread of the plunger engages with an internal screw thread of the cylindrical input drive at the distal end of the cylindrical input drive, so that rotation of the cylindrical input drive telescopically retracts or expands the plunger relative to the cylindrical input drive, and wherein the drive gear meshes with the axially extending gear of the rotatable transfer drive, so that as the cylindrical input drive is rotated by the rotatable transfer drive, the drive gear slides along the axially extending gear relative to the housing.