Cylinder-piston unit of a disposable injector having increased operational safety

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).