Drive mechanism for a drug delivery device and drug delivery device

摘要

The drive mechanism comprises a drive member inside a housing, a rotation member and a dose member. The drive member is rotatable with respect to the housing. The rotation member is also rotatable and unidirectionally rotationally engaged with the drive member. The dose member is able to move along a set/deliver path between a first axial position and a second axial position in either direction or to move along a cancel path from the second axial position to the first axial position. An engagement of the dose member with the rotation member causes the rotation member to rotate when the dose member is moved along the set/deliver path. The drive member is not rotated when the dose member is moved along the cancel path. A button in/out spline can be provided for the set/deliver path and a cancel spline for the cancel path.

主权项

1. A drive mechanism for a drug delivery device, comprising:
a housing, a piston rod arranged inside the housing, a drive member arranged inside the housing, the drive member being rotatable with respect to the housing, a rotation member rotatable with respect to the housing, a dose member, which is movable between a first axial position with respect to the housing and a second axial position that is axially spaced from the first axial position, an engagement of the dose member with the housing, the engagement allowing the dose member to move according to a set/deliver path between the first axial position and the second axial position in either direction or to move according to a cancel path from the second axial position to the first axial position, and an engagement of the dose member with the rotation member and a unidirectional rotational engagement of the rotation member with the drive member by a clutch in such a manner that the rotation member is rotated when the dose member is moved according to the set/deliver path and the drive member is not rotated when the dose member is moved according to the cancel path, wherein the piston rod comprises a thread engaged with the housing such that a rotational movement of the piston rod is converted into a movement of the piston rod with respect to the housing in a distal direction, wherein the piston rod comprises a track engaged with the drive member such that an axial movement of the piston rod relative to the drive member is allowed and a rotational movement of the drive member with respect to the housing is converted into a rotational movement of the piston rod with respect to the housing, and wherein the dose member is threadedly engaged with the rotation member.