Automatic applicator for liquid pharmaceutical preparations, particularly for insulin

Abstract

An injection device includes a housing with an inspection window and at least two springs. One of the at least two springs is a driving helical spring. A spring block is connected to the housing and secured against rotation relative to the housing. A coupling tube extends above the spring block and above the housing. The injection device includes a plunger at least partially surrounded by the coupling tube. The driving helical spring is connected to the spring block. The coupling tube is at least partially surrounded by the driving helical spring. At least a portion of the proximal end of the plunger is narrower than a first internal diameter of the coupling tube and wider than a second internal diameter of the coupling tube. The rotatable dose knob, the spring block, the coupling tube, the plunger, and the driving helical spring are arranged coaxially.

1 . An injection device comprising:
 a housing comprising an inspection window,   at least two springs, one of the at least two springs being a driving helical spring,   a spring block connected to the housing and secured against rotation relative to the housing,   a coupling tube extending above the spring block and above the housing   a plunger at least partially surrounded by the coupling tube,   wherein the driving helical spring is connected to the spring block,   wherein the coupling tube is at least partially surrounded by the driving helical spring,   wherein the coupling tube comprises a first internal diameter and a second internal diameter,   wherein the plunger comprises a proximal end and a distal end,   wherein at least a portion of the proximal end of the plunger is narrower than the first internal diameter of the coupling tube and wider than the second internal diameter of the coupling tube,   wherein the coupling tube comprises at least a first protrusion and a second protrusion,   wherein at least a portion of the first protrusion of the coupling tube is above the driving helical spring and above the spring block,   wherein at least a portion of the second protrusion of the coupling tube is below the inspection window of the housing,   wherein the spring block comprises an outer wall, an internal wall and a protrusion,   wherein at least a portion of the protrusion of the spring block is curved,   wherein the curved portion of the protrusion of the spring block at least partially extends beyond an outer diameter of the outer wall of the spring block,   wherein the spring block comprises a first hole and a second hole,   wherein the first hole of the spring block is separated from the second hole of the spring block by the internal wall of the spring block,   wherein the coupling tube extends through the first hole of the spring block and is arranged non-coaxially with the second hole of the spring block,   wherein the coupling tube is at least partially surrounded by a substantially cylindrical wall of a rotatable dose knob,   wherein the substantially cylindrical wall of the rotatable dose knob at least partially covers the housing, the curved protrusion of the spring block, the outer wall of the spring block, the driving helical spring, and the internal wall of the spring block, and   wherein the rotatable dose knob, the spring block, the coupling tube extending through the first hole, the plunger, and the driving helical spring are arranged coaxially.   
     
     
         2 . The injection device according to  claim 1 , wherein the curved protrusion of the spring block at least partially covers a curved portion of a wall of the housing. 
     
     
         3 . The injection device according to  claim 1 , wherein a distal end of the housing comprises an external diameter and a proximal end of the housing comprises an external diameter, the external diameter of the proximal end of the housing being smaller than the external diameter of the distal end of the housing. 
     
     
         4 . The injection device according to  claim 1 , wherein the coupling tube comprises an outer diameter that is smaller than the internal diameter of the first hole of the spring block and is larger than the internal diameter of the second hole of the spring block. 
     
     
         5 . The injection device according to  claim 1 , wherein the plunger comprises a thread and at least one longitudinal groove. 
     
     
         6 . The injection device according to  claim 1 , wherein the plunger comprises at least two longitudinal grooves. 
     
     
         7 . The injection device according to  claim 1 , wherein the spring block comprises a flange. 
     
     
         8 . The injection device according to  claim 1 , wherein the at least two springs comprise a second spring which is a helical spring. 
     
     
         9 . The injection device according  claim 1 , wherein the rotatable dose knob is coupled to the coupling tube such that when a dose is to be increased, the coupling tube rotates clockwise relative to the housing. 
     
     
         10 . The injection device according  claim 1 , wherein when the coupling tube is rotated by turning the rotatable dose knob for increasing a dose, a resilient arm of a pawl is displaced radially. 
     
     
         11 . The injection device according  claim 5 , wherein the longitudinal groove of the plunger is adapted to receive a key. 
     
     
         12 . The injection device according to  claim 11 , wherein the key is rotationally blocked in relation to the plunger. 
     
     
         13 . The injection device according to  claim 12 , wherein the key is a portion of a plunger guide, the plunger guide being located within an interior of the housing. 
     
     
         14 . The injection device according  claim 13 , wherein the plunger guide is axially movable relative to the housing. 
     
     
         15 . The injection device according  claim 1 , wherein the driving helical spring is a twisted spring. 
     
     
         16 . The injection device according  claim 1 , wherein a clutch element of the coupling tube is coupled with a resilient arm of a pawl. 
     
     
         17 . The injection device according  claim 1 , wherein when the coupling tube is rotated in a clockwise direction, a resilient arm of a pawl is displaced on slide edges, from one blocking edge to a neighboring edge. 
     
     
         18 . The injection device according to  claim 1 , wherein
 the at least two springs comprise a second spring, and   the second spring is at least partially outside the housing.   
     
     
         19 . The injection device according to  claim 1 , wherein the at least two springs comprise a second spring that comprises at least one coil. 
     
     
         20 . The injection device according to  claim 1 , wherein the plunger comprises a proximal non-threaded end and a distal threaded end. 
     
     
         21 . The injection device according to  claim 20 , wherein at least a portion of the proximal non-threaded end of the plunger is wider than the distal threaded end of the plunger. 
     
     
         22 . The injection device according to  claim 1 , wherein the first hole of the spring block comprises an internal diameter larger than an internal diameter of the second hole of the spring block. 
     
     
         23 . The injection device according to  claim 1 , wherein the rotatable dose knob is substantially axially immovable.