Injection device comprising an improved delivery element

Abstract

An injection device having a delivery element with an inner thread may be driven by rotation and includes a cylindrical outer wall region, which is substantially smooth. Such features provide a delivery element configured such that it is less intimidating to patients than known threaded rods, and may facilitate easy cleaning. The delivery element may be non-rotatably guided and axially spring-loaded, and may be inserted axially into the housing when the reservoir is replaced. The driving thread element for the delivery element may be mounted in the vicinity of the distal end of the housing.

1 . An injection pen for the administering of a fluid product, the pen comprising:
 a housing extending between a proximal end and a distal end, the distal end defining a passage opening;   a receptacle holder detachably coupled to the distal end of the housing, the receptacle holder for receiving a reservoir containing the fluid product for injection;   a delivery element for delivering the fluid product from a reservoir, the delivery element comprising a thrust sleeve with a thrust axis, a substantially smooth outer wall region and an internal thread engaged for axial displacement of the thrust sleeve, wherein the delivery element is distally movable relative to the housing along the thrust axis such that the substantially smooth outer region extends through and beyond the passage opening, and   a first, ring-shaped, sealing element comprising a sealing lip at the substantially smooth outer wall of the thrust sleeve of the delivery element for providing a sealing effect at the outer wall region of the thrust sleeve.   
     
     
         2 . The injection pen of  claim 1 , wherein the first sealing element lies in a sealing manner between a carrier element fastening the receptacle holder to the housing and the substantially smooth outer wall region of the delivery element. 
     
     
         3 . The injection pen of  claim 1 , wherein the delivery element is movable between a proximal-most position and a distal-most position, and wherein a length of the substantially smooth outer wall region corresponds at least to the distance between the proximal-most and distal-most positions. 
     
     
         4 . The injection pen of  claim 1  wherein the first sealing element is flexible and acts as a stripper at the outer wall region of the delivery element. 
     
     
         5 . The injection pen of  claim 2  wherein the substantially smooth outer wall region is provided with fine structures such as a micro- or nanostructuring with structures in the range below 10 micrometers for maintaining a seal between the thrust sleeve and the first sealing element. 
     
     
         6 . The injection pen of  claim 1  wherein the first sealing element and the thrust sleeve are arranged with a gap distance from each other and surfaces-at the gap are configured to have a hydrophobic coating forming a virtual seal at the gap. 
     
     
         7 . The injection pen of  claim 6  wherein the hydrophobic coating is selected from the group consisting of PTFE, PVDF or other hydrophobic coatings that may be formed as a thin coating. 
     
     
         8 . The injection pen of  claim 7  wherein the thin hydrophobic coating is in the range of a few micrometers. 
     
     
         9 . The injection pen of  claim 6  wherein the gap distance between parts to be sealed is below 0.5 mm, preferably below 0.25 mm. 
     
     
         10 . The injection pen of  claim 1  wherein the delivery element or the first sealing element is composed of a hydrophobic material. 
     
     
         11 . The injection pen of  claim 1  wherein the sealing lip has a contact angle with the outer wall region that is less than 90 degrees. 
     
     
         12 . The injection pen of  claim 1  wherein the thrust sleeve internal thread is a short internal thread at its proximal end. 
     
     
         13 . The injection pen of  claim 12  wherein an external threaded rod is guided in the short internal thread at the proximal end of the thrust sleeve for thrust sleeve motion. 
     
     
         14 . The injection pen of  claim 1  wherein the thrust sleeve has a plurality of guide cams on its exterior at its proximal end outside the smooth outer wall region for locking the thrust sleeve against relative rotation with respect to the housing. 
     
     
         15 . The injection pen of  claim 1  wherein the thrust sleeve is slidable to return from an extended position to an initial proximal position upon pressing a new carpule against a thrust flange of the thrust sleeve. 
     
     
         16 . The injection pen according to  claim 1  further comprising a second sealing element present between the carrier element and the housing. 
     
     
         17 . The injection pen according to  claim 16  where the carrier element is a bayonet sleeve and the second sealing element lies between the bayonet sleeve and a mechanism holder that is mounted to the housing. 
     
     
         18 . The injection pen according to  claim 16  where the second sealing element is in the form of a sealing ring. 
     
     
         19 . The injection pen according to  claim 16  further comprising a third sealing element present between a dosing sleeve and a stop sleeve located on the housing distally of the first sealing element. 
     
     
         20 . The injection pen according to  claim 19  further comprising a fourth sealing element present between a dosing sleeve and a push button located at the distal end of housing for initiating an injection. 
     
     
         21 . The injection pen of  claim 1  wherein the delivery element has a circular cylindrical outer wall region without structures such as threads or grooves.