Injection device with flexible dose selection

Abstract

An injection device incorporating a dose setting mechanism is presented where the dose setting mechanism contains a dose selector having one or more dose stops corresponding to a finite set of predetermined fixed doses, where the set of finite predetermined fixed doses includes a lowest fixed dose and one or more higher fixed doses, and where at least one of the one or more higher fixed doses is equal to the lowest fixed dose plus a fractional amount of the lowest fixed dose. The dose setting mechanism can further include a floating spline that is rotationally engaged with a snap element such that the snap element can rotate relative to the floating spline during both dose setting and dose delivery.

What is claimed: 
     
         1 . A dose setting mechanism comprising;
 a dose knob;   a dose selector;   a radial projecting rib positioned circumferentially on an inside surface of the dose selector; and   a snap element comprising a first protrusion and a second protrusion;   wherein engagement of the second protrusion with the radial projecting rib prevents distal axial movement of the dose selector.   
     
     
         2 . The dose setting mechanism of  claim 1  where the radial projecting rib further comprises a cut-out that is positioned in alignment with a dose stop that corresponds to one of a finite set of predetermined fix dose settings. 
     
     
         3 . The dose setting mechanism of  claim 1  where the first protrusion is in axial alignment with the second protrusion. 
     
     
         4 . The dose setting mechanism of  claim 2  where the radially projecting rib engages the second protrusion to prevent proximal axial movement of the dose selector when the first protrusion is not engaged with the dose stop 
     
     
         5 . The dose setting mechanism of  claim 1  where the dose selector only moves in a proximal direction to start a dose delivery when the second protrusion is aligned with a cut-out in the radially projecting rib. 
     
     
         6 . The dose setting mechanism of  claim 1  where the radially projecting rib comprises a plurality of cut-outs that are axially aligned to a plurality of dose stops positioned on an inside surface of the dose selector, where each dose stop corresponds to one of a finite set of predetermined fix dose settings. 
     
     
         7 . The dose setting mechanism of  claim 1 , where the dose selector can only move in a distal direction during dose delivery when the second protrusion is aligned with the cut-out of the radially projecting rib. 
     
     
         8 . The dose setting mechanism of  claim 6  where the dose knob can only move axially relative to the snap element, when the first protrusion is engaged with one of the dose stops of the dose selector. 
     
     
         9 . The dose setting mechanism of  claim 1  where the second protrusion will abut a proximal side of the radially projecting rib if the dose knob is released during dose delivery. 
     
     
         10 . The dose setting mechanism of  claim 1  where the dose selector further comprises a maximum dose hard stop. 
     
     
         11 . The dose setting mechanism of  claim 1  where the dose selector further comprises a zero dose hard stop. 
     
     
         12 . A dose setting mechanism comprising;
 a dose knob;   a dose selector comprising a dose stop;   a radial projecting rib positioned circumferentially on an inside surface of the dose selector and comprising a cut-out that is positioned in alignment with the dose stop that corresponds to one of a finite set of predetermined fix dose settings; and   a snap element comprising a first protrusion and a second protrusion;   wherein engagement of the second protrusion with the radial projecting rib prevents distal axial movement of the dose selector, and   wherein the dose selector only moves in a proximal direction to start a dose delivery when the second protrusion is aligned with a cut-out in the radially projecting rib.   
     
     
         13 . A dose setting mechanism comprising;
 a dose knob;   a dose selector comprising a plurality of dose stops positioned on an inside surface of the dose selector;   a radial projecting rib positioned circumferentially on an inside surface of the dose selector; and   a snap element comprising a first protrusion and a second protrusion;   wherein engagement of the second protrusion with the radial projecting rib prevents distal axial movement of the dose selector and where the second protrusion will abut a proximal side of the radially projecting rib if the dose knob is released during dose delivery, and   wherein the dose selector can only move in a distal direction during dose delivery when the second protrusion is aligned with the cut-out of the radially projecting rib.   
     
     
         14 . The dose setting mechanism of  claim 13  where the dose knob can only move axially relative to the snap element when the first protrusion is engaged with one of the dose stops of the dose selector. 
     
     
         15 . The dose setting mechanism of  claim 13  where the radially projecting rib comprises a plurality of cut-outs that are axially aligned to a plurality of dose stops positioned on an inside surface of the dose selector, where each dose stop corresponds to one of a finite set of predetermined fix dose settings.