Patent ID: 7241278

Claim:
A drug delivery device comprising: a piston rod having at least one threaded portion ( 4 ); a dose dial sleeve ( 17 ) threadedly engaged with a portion of the device and having a scale indicative of dose sizes and wherein the dose dial sleeve is rotatable during a dose setting operation so that it can be rotated to a position where a predetermined dose is indicated on the scale; a drive sleeve ( 20 ) for driving the piston rod; and a clutch ( 21 ), which is comprised of one or more components ( 33 , 32 ), that releasably couples the dose dial sleeve ( 17 ) and the drive sleeve ( 20 ); and wherein: (i) during the dose setting operation the dose dial sleeve ( 17 ) and the drive sleeve ( 20 ) are coupled by the clutch so that they rotate together; and (ii) during injecting of medication from the device, the dose dial sleeve ( 17 ) is decoupled from the drive sleeve ( 20 ) and so that it rotates back to an original pre-dose setting position upon completion of the injection but the drive sleeve ( 20 ) does not rotate during injecting of medication but instead moves in a longitudinal direction toward an injecting end of the device.