Medicament delivery device with rotator retaining the plunger rod

1. A medicament delivery device which extends along a longitudinal axis and comprises:

a generally tubular elongated housing having a proximal end and a distal end, wherein said generally tubular elongated housing is arranged to accommodate a medicament container;

a drive unit comprising a drive element and a plunger rod operably arranged to act on said medicament container; and

a tubular element rotatably arranged in relation to said generally tubular elongated housing and operably arranged to said plunger rod, wherein the plunger rod comprises at least one holding member and the tubular element comprises at least one arm extending generally transversal to the longitudinal axis of the medicament delivery device, wherein the at least one arm is arranged to engage the at least one holding member on said plunger rod to releasably hold said drive unit in an energy accumulated state, and wherein the at least one holding member of said plunger rod is at least one recess or at least one through hole or at least one slot comprising a side wall that is inclined in a radial direction to facilitate positioning the at least one arm in engagement with the at least one holding member, wherein said generally tubular elongated housing further comprises a proximally-directed protrusion at said distal end, wherein said plunger rod further comprises a slot on a distally directed end surface of said plunger rod, wherein said slot is sized to cooperate with said proximally-directed protrusion to rotationally lock said plunger rod to said generally tubular elongated housing when said drive unit is in said energy accumulated state, and wherein said proximally-directed protrusion at said distal end of the generally tubular elongated housing is sized to disengage from said slot when said drive unit is released from said energy accumulated state.

2. The medicament delivery device according to claim 1 , wherein the at least one arm is a rigid arm.

3. The medicament delivery device according to claim 2 , wherein the at least one arm is axially rigid but radially flexible.

4. The medicament delivery device according to claim 1 , wherein the at least one arm is arranged on an inner circumferential surface or on a rim of the tubular element.

5. The medicament delivery device according to claim 1 , wherein said tubular element is arranged coaxially outside said plunger rod.

6. The medicament delivery device according to claim 1 , wherein said generally tubular elongated housing comprises a proximal housing part and a distal housing part and wherein the plunger rod is rotationally locked to the distal housing part when the drive unit is the energy accumulated state.

7. The medicament delivery device according to claim 1 , wherein the medicament delivery device further comprises an activator displaceably arranged in relation to said generally tubular elongated housing and operably arranged to said tubular element such that the displacement of said activator causes said tubular element to be rotated such that the at least one arm disengages from the at least one holding member on said plunger rod whereby the drive unit is released from the energy accumulated state.

8. The medicament delivery device according to claim 7 , wherein said activator is slidably arranged along the longitudinal axis of the medicament delivery device between the generally tubular elongated housing and the tubular element.

9. The medicament delivery device according to claim 8 , wherein the activator comprises a medicament delivery member guard which is tubular shaped and configured to protrude a certain distance from the proximal end of the generally tubular elongated housing.

10. The medicament delivery device according to claim 9 , wherein said tubular element comprises at least one interaction member on an outer circumferential surface of said tubular element, wherein said at least one interaction member is arranged to cooperate with at least one activator element arranged on said activator.

11. The medicament delivery device according to claim 10 , wherein said at least one interaction member is arranged inclined in relation to the longitudinal axis of the medicament delivery device.

12. The medicament delivery device according to claim 11 , wherein said at least one interaction member comprises an inclined ledge and wherein said at least one activator element comprises a protrusion, wherein the protrusion acts on said inclined ledge to rotate said tubular element when said activator is linearly displaced in relation to said generally tubular elongated housing when the medicament delivery member guard is pressed against a dose delivery site.

13. The medicament delivery device according to claim 12 , wherein said activator is arranged with a resilient force member designed to return said activator when said medicament delivery device is removed from the dose delivery site.

14. The medicament delivery device according to claim 13 , wherein said tubular element comprises a locking member arranged to interact with said at least one activator element on said activator for locking said activator when returned from moving towards a distal end of the medicament delivery device.

15. The medicament delivery device according to claim 14 , wherein said locking member is a flexibly tongue having a stop ledge.

16. The medicament delivery device according to claim 1 , wherein the medicament container is arranged with a medicament delivery member though which medicament may be expelled.

17. The medicament delivery device according to claim 1 , wherein said medicament delivery device is an injection device.