CPC A61M 5/3155 (2013.01) [A61M 5/315 (2013.01); A61M 5/31528 (2013.01); A61M 5/31583 (2013.01); A61M 2005/2026 (2013.01); A61M 2005/314 (2013.01); A61M 2005/3152 (2013.01); A61M 5/31533 (2013.01)] | 21 Claims |
1. A drive mechanism of a drug delivery device, the drive mechanism comprising:
a housing;
a piston rod to operably engage with a piston of a cartridge to displace the piston of the cartridge in a distal direction to dispense a medicament during dose dispensing;
a rotatable member arranged in the housing, the rotatable member comprising at least one protrusion extending radially from a surface of the rotatable member, the rotatable member being rotatable in a dose incrementing direction relative to the housing during dose setting and rotatable in a dose decrementing direction relative to the housing to drive the piston rod in the distal direction during the dose dispensing, the dose decrementing direction being opposite to the dose incrementing direction; and
a clutch member arranged in the housing, the clutch member comprising at least one clutch element that at least partially extends radially toward the at least one protrusion,
wherein the at least one clutch element is configured to, as the rotatable member is rotated in the dose decrementing direction relative to the housing to drive the piston rod in the distal direction during the dose dispensing, engage with the at least one protrusion and to resiliently deform in response to the engaging with the at least one protrusion, thereby producing a variable holding force on the rotatable member during the dose dispensing, wherein the drive mechanism is configured such that the variable holding force on the rotatable member by the at least one clutch element is adjustable during the dose dispensing.
|