Sub-assembly of a medicament delivery device and a medicament delivery device

1. A sub-assembly of a medicament delivery device, the sub-assembly comprising:

a plunger rod comprising an outer surface, where the plunger rod is biased;

a main body extending longitudinally to partially surround the outer surface of the plunger rod, where the main body comprises a flexible arm that is directly and releasably connected to the outer surface of the biased plunger rod; and

a coupling member axially fixed, partially surrounding, and rotatable relative to an outside surface of the main body such that the outside surface of the main body is between the outer surface of the plunger rod and an inner surface of the coupling member when the coupling member rotates from a first position to a second position, where the inner surface of the coupling member confines the flexible arm in a locking engagement with the outer surface of the plunger rod to prevent axial movement of the plunger rod when the coupling member is in the first position,

wherein the main body comprises a first locking element and the coupling member comprises a second locking element having a protrusion extending radially inward from an inner surface of the coupling member,

wherein rotation of the coupling member from the first position causes the first locking element and the second locking element to be releasably engaged with each other such that the coupling member is prevented from rotating to an axial release position relative to the main body, and

wherein movement of the coupling member to the second position allows the flexible arm to disengage from and unlock the plunger rod,

wherein the first locking element extends in an axial direction from the main body, then extends radially outwards in an arch, and then extends radially inwards so that a free end of the first locking element is engaged with the second locking element to prevent the coupling member from rotating relative to the main body.

2. The sub-assembly of the medicament delivery device according to claim 1 , wherein a distance between the arch and a central axis of the main body is larger than a distance between the central axis and other portions of the first locking element, and also larger than an outer radius of the coupling member.

3. The sub-assembly of the medicament delivery device according to claim 2 , wherein the coupling member includes a bore at a distal end thereof and where the protrusion delimits the second locking element.

4. The sub-assembly of the medicament delivery device according to claim 3 , wherein the protrusion has a ramp-shaped first surface which extends inwards from an inner surface of the bore for bending the first locking element and a wall-shaped second surface which extends orthogonally from the inner surface of the bore, for fixing the first locking element relative to the coupling member.

5. The sub-assembly of the medicament delivery device according to claim 4 , wherein the main body further includes a biasing member guide which is fixed to the coupling member and a distal cap in relation to which the coupling member is rotatable.

6. The sub-assembly of the medicament delivery device according to the claim 5 , wherein the first locking element extends from the distal cap, the distal cap comprises a latch at a distal half thereof, the coupling member comprises a ledge, and the latch is engaged with the ledge to prevent the coupling member from releasing out of the distal cap in the axial direction.

7. The sub-assembly of the medicament delivery device according to claim 3 , wherein the first locking element is a radially flexible tab and the second locking element is a recess.

8. The sub-assembly of the medicament delivery device according to the claim 3 wherein the sub-assembly further comprises a biasing member which biases the plunger rod.

9. The sub-assembly of the medicament delivery device according to claim 2 , wherein the main body includes a rib which divides the main body into a proximal section and a distal section, and wherein the coupling member is arranged on the proximal section, and a fixed end of the first locking element is arranged on the distal section.

10. The sub-assembly of the medicament delivery device according to claim 2 , wherein the coupling member comprises a closed loop at an outer proximal end thereof, and the protrusion situated in the closed loop, and wherein the protrusion and a profile of the closed loop delimit the second locking element for preventing the coupling member from rotating relative to the main body.

11. The sub-assembly of the medicament delivery device according to claim 1 , wherein the first locking element radially extends at a free end of the main body, the second locking element is arranged on the inner surface of the coupling member, and the first locking element is engaged with the second locking element to prevent the coupling member from rotation and axial movement relative to the main body.

12. The sub-assembly of the medicament delivery device according to claim 11 , wherein the main body comprises a rib which divides the main body into a proximal section and a distal section, the coupling member is arranged on the proximal section.

13. The sub-assembly of the medicament delivery device according to the claim 11 , wherein the first locking element is a projection and the second locking element is a recess.

14. A sub-assembly of a medicament delivery device, the sub-assembly comprising:

a plunger rod which is biased;

a main body comprising a flexible arm that is directly and releasably connected to the biased plunger rod; and

a coupling member rotatable relative to the main body and the plunger rod from a first position to a second position and is axially fixed relative to the main body, where the coupling member confines the flexible arm in a locking engagement with the plunger rod to prevent axial movement of the plunger rod when the coupling member is in the first position,

wherein the main body comprises a first locking element and the coupling member comprises a second locking element having a protrusion extending radially inward from an inner surface of the coupling member,

wherein rotation of the coupling member from the first position causes the first locking element and the second locking element to be releasably engaged with each other such that the coupling member is prevented from rotating to an axial release position relative to the main body,

wherein movement of the coupling member to the second position allows the flexible arm to disengage from and unlock the plunger rod, and

wherein the first locking element extends in an axial direction from the main body, then extends radially outwards in an arch, and then extends radially inwards so that a free end of the first locking element is engaged with the second locking element to prevent the coupling member from rotating relative to the main body.