Patent ID: 8708974

Claim:
A cylinder-piston unit ( 10 ) of a needle-free disposable injector, comprising: a cylinder ( 20 ) and an end face ( 12 ) including at least one nozzle-like discharge element ( 26 ) each having a mouth ( 29 ), the cylinder ( 20 ) having a cylinder interior ( 31 ) having at least one passage ( 25 ), each of said passage ( 25 ) connecting the cylinder interior ( 31 ) to one of said at least one mouth ( 29 ), the first end face ( 12 ) of the cylinder-piston unit ( 10 ) has at least one skin press-in area ( 60 ), each engaging around one of said at least one mouth ( 29 ), and a skin press-on area ( 80 ), surrounding the at least one skin press-in area ( 60 ), the skin press-on area ( 80 ) having a first surface ( 81 ), each of the at least one skin press-in area ( 60 ) comprises an inner circumferential web ( 62 ), delimiting one of said at least one nozzle-like discharge element ( 26 ) having the mouth ( 29 ) protruding beyond the first surface ( 81 ) of the skin press-on area ( 80 ), and an outer circumferential web ( 63 ) in surrounding relationship with the inner circumferential web ( 62 ), each of the webs ( 62 , 63 ) for pressing into skin ( 6 ) in an operative position of the injector, the inner circumferential web ( 62 ) in the operative position of the injector is configured for stretching the skin ( 6 ) in an area ( 91 ) surrounded by said inner circumferential web ( 62 ), the inner circumferential web ( 62 ) and the surrounding outer circumferential web ( 63 ) each protrude beyond the first surface ( 81 ) of the skin press-on area ( 80 ) and delimit a first recess ( 71 ) between the inner circumferential web ( 62 ) and the surrounding outer circumferential web ( 63 ) for receiving and forming an O-ring shaped skin ( 6 ) area ( 92 ) for sealing off and preventing wet shots of one of said at least one nozzle-like discharge element ( 26 ), the O-ring shaped skin ( 6 ) area ( 92 ) surrounds the inner circumferential web ( 62 ) and of which a depth of the O-ring shaped skin area ( 92 ) measured parallel to a center axis ( 15 ) of the cylinder-piston unit ( 10 ) is at least a quarter of its width in a plane oriented normal thereto, the skin press-on area ( 80 ), at least during an injection, is offset counter to an injection direction ( 2 ) relative to an end face segment ( 61 ) of one of the at least one press-in skin area ( 60 ), the first surface ( 81 ) of the press-on skin area ( 80 ) projected into a plane normal to the center axis ( 15 ) is at least as large as a second surface of the end face segment ( 61 ) of the at least one press-in skin area ( 60 ) projected into the same plane, an adhesive ( 72 ) is operatively positioned on the first recess ( 71 ), and, the press-on skin area ( 80 ) has a second recess ( 83 ) for receiving skin ( 6 ) for forming a second seal and preventing wet shots of said at least one nozzle-like discharge element ( 26 ).