Drug delivery device

1 . A drug delivery device comprising a housing, a delivery unit, a drive unit and a pumping system, the delivery unit comprising a subcutaneous delivery system and a needle actuator system, the subcutaneous delivery system comprising a slidable needle support and an injection needle mounted to the slidable needle support, the needle support movable with respect to the housing from a retracted position where the needle is mounted within the housing, to an extended position where the needle projects through a skin contact wall of the housing for subcutaneous delivery, the needle actuator system comprising an actuation disc rotatably mounted to a housing wall portion within the housing configured to displace the slidable needle support from the retracted position to the extended position by rotation of the actuation disc, the drug delivery device further comprising a rotary drive shaft or stub comprising a coupling interface, the actuation disc comprising a coupling interface engageable with the coupling interface of the rotary drive shaft or stub, the drug delivery device further comprising a motor coupled to the rotary drive shaft or stub, wherein the needle actuator system further comprises a drive decoupling mechanism comprising a cam arrangement between the actuation disc and the housing wall portion and a spring, the spring and cam arrangement configured to effect an axial displacement of the actuation disc during rotation of the actuation disc causing displacement of the slidable needle support from the retracted to the extended position, the axial displacement causing a decoupling of the rotor drive shaft or stub coupling interface from the coupling interface of the actuation disc.

2 . The drug delivery device according to claim 1 , wherein the drive decoupling mechanism comprises a spring engagement flange or shoulder connected to the actuation disc via a connection portion extending through an orifice in the housing wall portion, the spring positioned in a prestressed manner between the spring engagement flange and a side of the housing wall portion opposite a side where the actuation disc is positioned.

3 . The drug delivery device according to claim 1 , wherein the spring is mounted on a rear side of the housing wall portion and the actuation disc is mounted on a front side of the housing wall portion.

4 . The drug delivery device according to claim 1 , wherein the cam arrangement is positioned between a rear side of the actuation disc and a front side of the housing wall portion, the drive coupling interface on the actuation disc being mounted on a front side of the actuation disc.

5 . The drug delivery device according to claim 1 , wherein the cam arrangement comprises a cam track on one of the actuation disc and front side of the housing wall portion and a cam pin on the other of the actuation disc and front side of the housing wall portion.

6 . The drug delivery device according to claim 1 , wherein the cam arrangement comprises a cam track having a slope at an inclination angle slope angle β relative to a plane orthogonal to the direction of displacement of the actuation disc that is greater than the coefficient of friction of the cam arrangement such that the axial biasing of the spring causes the actuation disc to rotate to the fully extended position.

7 . The drug delivery device according to claim 1 , wherein the needle actuator mechanism comprises a pivoting actuation lever having a pivot portion mounted pivotally to the housing wall portion and a lever arm portion extending from the pivot portion engageable with the actuation disc, the lever arm portion comprising a needle support coupling engaging a complementary coupling of the needle support for displacing the needle support from the retracted to the extended position.

8 . The drug delivery device according to claim 7 , wherein the actuation disc comprises a lever engagement member in the form of an indent configured to engage a tip ( 28 ) of the lever arm portion.

9 . The drug delivery device according to claim 1 , wherein the drive decoupling mechanism comprises a spring engagement member in the form of a button comprising the spring engagement flange or shoulder assembled to the actuation disc through an orifice in the housing wall portion.

10 . The drug delivery device according to claim 1 , wherein the motor coupled to the rotary drive shaft or stub is also coupled to a pumping system of the drug delivery device for pumping of the liquid drug from a drug container to the needle.

11 . The drug delivery device according to claim 1 , wherein the rotary drive shaft or stub comprises gear teeth for coupling to a rotor of the motor or pumping system.

12 . The drug delivery device according to claim 1 , wherein the coupling interface between the rotary drive shaft or stub and the actuation disc comprises a key and slot arrangement.

13 . The drug delivery device according to claim 1 , wherein the delivery unit and drive unit are formed as separate parts that may be assembled together, the delivery unit being a disposable single use part and the drive unit a reusable part.

14 . The drug delivery device according to claim 1 , wherein the pumping system comprises a pneumatic pumping system applying pressure on a drug container mounted in the drug delivery device.

15 . The drug delivery device according to claim 14 , wherein the drug container is in the form of a cartridge with a plunger.