Patent ID: 8167850

Claim:
A cylinder/piston unit including a cylinder ( 10 ) and a piston ( 50 ) guided within the cylinder ( 10 ) and sealed off in a sterile manner by a rubber seal, the cylinder ( 10 ) and the piston ( 50 ) enclosing a chamber ( 30 ) that can be filled at least temporarily with active substance, and the cylinder ( 10 ) having at least one discharge element ( 36 ) at its front end ( 11 ), characterized in that; the piston ( 50 ) having a resting rear position ( 99 ) sealed off relative to the cylinder ( 10 ) in a sterile manner by a static front sealing element ( 65 , 105 ) and by a static rear sealing element ( 85 ), both the front sealing element ( 65 , 105 ) and the rear sealing element ( 85 ) having respectively a sealing position ( 67 , 87 ) where the front sealing element ( 65 , 105 ) and the rear sealing element ( 85 ) each respectively bear on a wall ( 31 , 47 ) of the cylinder ( 10 ) and the front sealing element ( 65 , 105 ) and the rear sealing element ( 85 ) each respectively bear on a wall ( 64 , 72 ) of the piston ( 50 ), arranged spatially behind the front static sealing element ( 65 , 105 ) and the rear static sealing element ( 85 ), the piston ( 50 ) having a parking area ( 68 , 88 ) for receiving upon movement of the piston ( 50 ) the respective front sealing element ( 65 , 105 ) and the rear sealing element ( 85 ), the parking area ( 68 , 88 ) being unoccupied prior to the movement of the piston ( 50 ), the piston ( 50 ) having an actuated state or position with the individual static front sealing element ( 65 , 105 ) and the static rear sealing element ( 85 ) transferred from their respective sealing position ( 67 , 87 ) into a parked position ( 69 , 89 ) located in the parking area ( 68 , 88 ), and each of the front sealing element ( 65 , 105 ) and the rear sealing element ( 85 ) in the respective parked position ( 69 , 89 ) touches only the cylinder wall ( 47 , 48 ) or only the piston wall ( 64 , 84 ), at least one dynamic sealing element ( 52 ) is arranged on the piston side between the static sealing front sealing element ( 65 , 105 ) and the static rear sealing element ( 85 ) and the at least one dynamic sealing element ( 52 ) bears on the inner wall ( 31 ) of the cylinder ( 10 ) at least when the piston ( 50 ) is actuated.