Injection Device

Abstract

An injection device with a travelling clutch which can be shifted between two different positions by the activation of an injection button. In the first position, the injection button and the driver is allowed to rotate relatively to the piston rod, which is blocked from rotation by the clicker element. In the second position, the drive sleeve and the injection button is axially movable while the piston rod is allowed to rotate.

1 . A drug delivery device comprising:
 a housing,   a piston rod having one or more threads,   a nut member disposed within the housing, that cooperates with the piston rod so that the piston rod is screwed in a distal direction when rotated relatively to the member,   a drive sleeve that rotates the piston rod during dose administration,   a releasable coupling operational between a first position and a second position to secure the piston rod against rotation during dose setting, but during dose administration allows the piston rod to rotate.   
     
     
         2 . A drug delivery device according to  claim 1  wherein the coupling comprises a slider slidably connected to the housing. 
     
     
         3 . A drug delivery device according to  claim 2  wherein the coupling comprises a clicker element coupled to the slider. 
     
     
         4 . A drug delivery device according to  claim 3  wherein the clicker element is both axially and rotational locked to the slider in the first position. 
     
     
         5 . A drug delivery device according to  claim 3  wherein the clicker element is rotational released from the slider in the second position. 
     
     
         6 . A drug delivery device according to  claim 5  wherein the clicker element is shifted between its locked and its released position by axial movement of an injection button. 
     
     
         7 . A drug delivery device according to  claim 6  wherein the injection button is connected to the drive sleeve in a way making the injection button axially displaceable relatively to the drive sleeve. 
     
     
         8 . A drug delivery device according to  claim 1 , wherein the releaseable coupling further locks the drive sleeve to prevent rotation during dose administration. 
     
     
         9 . A drug delivery device according to  claim 8 , wherein the coupling comprises a slider that is slidably connected to the housing. 
     
     
         10 . A drug delivery device according to  claim 9 , wherein the coupling comprises a clicker element. 
     
     
         11 . A drug delivery device according to  claim 8 , wherein the clicker element is shifted between its locked and its released position by axial movement of an injection button ( 30 ) which is located at an end of the device. 
     
     
         12 . A drug delivery device according to  claim 1 , further comprising an injection button located at an end of the device wherein the injection button is moveable in an axial direction to shift the releasable coupling from one position to another position. 
     
     
         13 . A drug delivery device according to  claim 12 , wherein the injection button rotates during dose setting along with a dose dial sleeve  40 .