<p>The brewing unit has an axially adjustable piston which is moved in brewing position of filling opening (3). A closing plate (5) is provided in end of cylinder (2). A gear wheel (9) is rotatably mounted on closed chamber (8). The gear wheel and connecting rods (16) are eccentrically hinged with respect to articulation points (15). The ends of the closure flap are hinged at the articulation points (18). The articulation points (15,18) and axes of rotation (10) of gear wheel are set in straight line which is parallel to the longitudinal center axis of the cylinder.</p>
