Gearing mechanism for a dose delivery device

Abstract

The invention relates to a gearing mechanism for a dose delivery device wherein the dose can be set by rotating a dose setting member ( 2, 102 ), and by which the dose setting member ( 2, 102 ) and a push-button ( 4 ) elevates from one end of the device proportional to the set dose from a position fixed relative to a housing ( 1, 101 ), and by which an injection of the set dose can be clone by pressing the push-button back to its not elevated position, moving a piston rod ( 10, 110 ) cooperating with the piston in an cartridge ( 12, 112 ) and expelling a medicament out of the through a needle. The gearing mechanism is arranged in the device in such a way, that the loss of energy is very low.

1 . A gearing mechanism for a dose delivery device comprising
 a first gearing member ( 6 ,  106 ) with a first thread,   a driver ( 8 ,  108 ) with a second thread,   a second gearing member ( 7 , 107 ) with two threads engaging the first and the second thread respectively,   a housing ( 1 ,  101 ) for interfacing a user and wherein the gearing mechanism is coaxially arranged and   a dose setting member ( 2 ,  102 ) rotationally connected to the gearing mechanism during dose setting ( 2 ,  102 ),   wherein the first and the second threads are headed in opposite directions and   wherein the first gearing member ( 6 ,  106 ) and the driver ( 8 ,  108 ) are rotational connected via a track allowing axial movement,   characterised by   that the gearing mechanism rotates relative to the housing ( 1 ,  101 ) when a dose is set by rotating the dose setting member ( 2 ,  102 ).   
     
     
         2 . A device according to  claim 1  characterized by that the track between the first gearing member ( 6 ,  106 ) and the driver ( 8 ,  108 ) does not allow rotational movement between the parts. 
     
     
         3 . A device according to  claim 1  characterized by that the rotational connection between the first gearing member ( 6 ,  106 ) and the driver ( 8 ,  108 ) is a helical track. 
     
     
         4 . A device according to  claim 1  characterized by that a dial ( 5 ,  105 ) which is threadedly engaged with the housing ( 1 ,  101 ) is rotated together with a dose setting member ( 2 ,  102 ) when a dose is set, and not rotating together with the dose setting member ( 2 ,  102 ), when the dose is injected. 
     
     
         5 . A device according to  claim 4  characterized by that the dial ( 5 ,  105 ) is connected to the dose setting member ( 2 ,  102 ) via a one-way ratchet. 
     
     
         6 . A device according to  claim 4  characterized by that the dial ( 5 ,  105 ) is connected to the first gearing member ( 6 , 106 ) via a one-way ratchet. 
     
     
         7 . A device according to  claim 1  characterized by that the lead screw ( 10 , 110 ) is rotationally locked to the housing ( 1 ,  101 ). 
     
     
         8 . A device according to  claim 1  characterized by that the lead screw ( 10 ,  110 ) is engaged with the housing ( 1 ,  101 ) via a helical track.