Drive assembly suitable for use in a drug delivery device and drug delivery device

1. A drive assembly for use in a drug delivery device, the drive assembly comprising:

a housing having a proximal end and a distal end;

an axis extending between the proximal end and the distal end;

at least one drive member;

a piston rod adapted to be driven along the axis by the drive member; and

an indicator adapted to provide positional information about a position of the piston rod relative to the proximal end,

wherein

the indicator and the piston rod are configured to convert movement of the piston rod with respect to the housing into a rotational movement of the indicator, and the indicator comprises a rotation member configured to convert movement of the piston rod into the rotational movement of the indicator with the indicator being coupleable to the piston rod via the rotation member and wherein at least a part of the rotation member is arranged within the piston rod, characterized in that the rotation member runs from outside of the piston rod to inside of the piston rod through an opening of the piston rod, the opening being provided on that side of the piston rod that faces the proximal end.

2. The drive assembly according to claim 1 ,

wherein the drive assembly is configured to move the piston rod unidirectionally along the axis.

3. The drive assembly according to claim 1 ,

wherein the indicator has an indication surface that is provided with a plurality of index elements, the drive assembly being configured for at least one of the index elements to be visible from outside of the drive assembly.

4. The drive assembly according to claim 1 ,

wherein the drive member is movable along the axis with respect to the housing and the indicator is coupled to the drive member with the indicator following an axial movement of the drive member.

5. The drive assembly according to claim 1 ,

wherein the drive assembly is configured to restrict or prevent distal movement of the indicator along the axis with respect to the housing or with respect to the drive member.

6. The drive assembly according to claim 1 ,

wherein one of the rotation member and the piston rod has a protrusion that is configured to mechanically interact with the other one of the rotation member and the piston rod for converting the movement of the piston rod into rotational movement of the rotation member.

7. The drive assembly according to claim 6 ,

wherein the respective protrusion comprises one of a male thread, a knob, a rib, a lug or a pin.

8. The drive assembly according to claim 6 ,

wherein both of the rotation member and the piston rod have a protrusion with the protrusions being configured to mechanically interact.

9. The drive assembly according to claim 6 ,

wherein the protrusion engages the indentation.

10. The drive assembly according to claim 1 ,

wherein at least one of the rotation member and the piston rod has an indentation that is configured to mechanically interact with the other one of the rotation member and the piston rod for converting the movement of the piston rod into rotational movement of the rotation member.

11. The drive assembly according to claim 10 ,

wherein the indentation comprises one of a slit and a female thread.

12. The drive assembly according to claim 1 ,

wherein the rotation member has a section which is configured to threadedly engage the piston rod.

13. The drive assembly according to claim 1 ,

wherein the drive assembly is configured to move the piston rod distally along the axis and to rotate the piston rod.

14. The drive assembly according to claim 1 ,

wherein the indicator is coupleable to the piston rod with a coupling being configured to convert rotational movement of the piston rod into rotational movement of the indicator of equal rotation angles.

15. The drive assembly according to claim 1 ,

wherein the indicator is coupleable to the piston rod with a coupling being configured to convert rotational movement of the piston rod into rotational movement of the indicator of different rotation angles.

16. The drive assembly according to claim 1 ,

wherein the drive assembly is configured to restrict or prevent rotational movement of the piston rod.

17. The drive assembly according to claim 1 ,

wherein the drive assembly is configured to convert a distal movement of the piston rod along the axis into rotational movement of the indicator.

18. A drug delivery device according to claim 1 comprising a plurality of doses of a drug.

19. The drug delivery device according to claim 18 ,

wherein the drive assembly is configured for the indicator to rotate when a dose is dispensed from the drug delivery device.