Medicament delivery devices

摘要

A medicament delivery device comprises a housing, a telescopic piston rod assembly for driving a bung of a medicament container, and a drive mechanism for the telescopic piston rod assembly. The telescopic piston rod assembly comprises a plunger for driving a bung, a key for allowing predominantly axial movement between the plunger and the housing and an input drive telescopically coupled to the plunger and supported for rotational and axial movement relative the housing. The drive mechanism additionally comprises a transfer drive that operates to rotate the input drive. As the input drive rotates, it moves axially relative to the housing, expanding telescopically relative to the plunger.

主权项

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.