Patent attributes
A drive mechanism suitable for use in drug delivery devices is disclosed. The drive mechanism may be used with injector-type drug delivery devices, such as those permitting a user to set the delivery dose. The drive mechanism may include a housing, a piston rod, and a unidirectional coupling between the housing and the piston rod. The drive mechanism may also include a dose dial sleeve and a drive sleeve, with a clutch mean located therebetween to prevent relative rotation between the dial sleeve and the drive sleeve when in a coupled state and to permit relative rotation between the dial sleeve and the drive sleeve when in a de-coupled state.