Administration mechanism for a medicament delivery device

1 . An administration mechanism for a medicament delivery device, where the administration mechanism comprises:

a movable sleeve comprising:

an outer surface, and

a follower located on the outer surface; and

a delivery member cover comprising:

a longitudinal axis;

a distal portion comprising at least one distally extending leg;

a guide surface located at a distal end of the at least one leg; and

at least one arm that proximally and circumferentially extends from an edge of the at least one leg at an obtuse angle relative the longitudinal axis, where the delivery member cover is configured to be axially displaceable relative to the movable sleeve between a first position, a second position and a third position; and

a first resilient member that biases the delivery member cover in a proximal direction,

wherein the guide surface comprises an end face that is slidably engaged with the follower when the delivery member cover moves from the first position to the second position,

wherein the movable sleeve further comprises a lock extending radially from the outer surface and configured to flex radially inward.

2 . The administration mechanism of claim 1 , wherein the at least one leg comprises two legs.

3 . The administration mechanism of claim 2 , wherein the at least one arm comprises four arms and each leg has two of the arms.

4 . The administration mechanism of claim 1 , wherein the at least one arm comprises four arms.

5 . The administration mechanism of claim 1 , wherein the distal portion of the delivery member cover engages and pushes the lock radially inward as the delivery member cover moves relative to the movable sleeve.

6 . The administration mechanism of claim 1 , wherein the guide surface is oblique with respect to the longitudinal axis of the delivery member cover.

7 . The administration mechanism of claim 6 , wherein the oblique guide surface defines an angle that is less than 90 degrees as measured relative to the longitudinal axis.

8 . The administration mechanism of claim 1 , wherein the follower comprises a radial projection.

9 . The administration mechanism of claim 1 , wherein the follower is a circumferentially extending rib projecting outward from the outer surface of the movable sleeve.

10 . The administration mechanism of claim 1 , wherein the movable sleeve rotates relative to the first resilient member when the delivery member cover moves from the first position to the second position.

11 . The administration mechanism of claim 1 , wherein an inside surface of the at least one leg covers a proximal part of the outer surface of the movable sleeve.

12 . The administration mechanism of claim 1 , wherein the at least one arm is located at a distance that is proximal to the guide surface.

13 . An administration mechanism for a medicament delivery device, where the administration mechanism comprises:

a movable sleeve comprising:

an outer surface,

a follower located on the outer surface, and

a lock positioned on a flexible tongue and extending radially from the outer surface;

a delivery member cover comprising:

a longitudinal axis;

a distal portion comprising at least one distally extending leg;

a guide surface located at a distal end of the at least one leg; and

at least one arm that proximally and circumferentially extends from an edge of the at least one leg at an obtuse angle relative the longitudinal axis, where the delivery member cover is configured to be axially displaceable relative to the movable sleeve between a first position, a second position and a third position; and

a first resilient member that exerts a proximally directed biasing force on the delivery member cover during movement of the delivery member cover from the first position to the second position and to the third position,

wherein an inside surface of the at least one leg engages and pushes the lock and the tongue radially inward as the delivery member cover moves relative to the movable sleeve, and

wherein the guide surface is oblique with respect to the longitudinal axis of the delivery member cover and comprises an end face that is slidably engaged with the follower when the delivery member cover moves from the first position to the second position.

14 . The administration mechanism of claim 13 , wherein the tongue flexes radially inward relative to the outer surface and then flexes radially back outward as the delivery member cover moves from the first position to the second position and then to the third position.

15 . The administration mechanism of claim 13 , wherein the lock prevents axial movement of the delivery member cover relative the movable sleeve when the delivery member cover is in the third position.

16 . The administration mechanism of claim 13 , wherein the lock engages the distal portion of the delivery member cover after the delivery member cover has moved to the third position.

17 . The administration mechanism of claim 13 further comprising a hollow plunger rod containing a proximal portion of a second resilient member that biases the plunger rod proximally.

18 . The administration mechanism of claim 13 , wherein the at least one distally extending leg comprises two distally extending legs and the at least one arm comprises four arms, wherein each leg comprises two of the arms proximally and circumferentially extend from an edge of each respective leg.

19 . The administration mechanism of claim 18 , wherein each arm is located at a distance that is proximal to the guide surface on each leg.