Abstract: A machine for preparing coffee, including a brewing chamber; a water supply for supplying a flow of water to the brewing chamber; and an adaptive flow control device for the flow of water, positioned in series with the water supply and the brewing chamber.

Abstract: The device comprises a body (2-4) having an inlet passage (7) and an outlet passage (18) for the liquid, and wherein there is defined an internal cavity (8) which by means of a movable intermediate member (9, 12) is divided into a first and second chamber (10, 11) which are sealingly separated from one another, preferably by means of a diaphragm member (9). The first chamber (10) is adapted to be put into communication with the inlet passage (7); a resilient member (15) is provided in the second chamber (11) and tends to urge the movable member (9, 12) towards the first chamber (10). The movable member (9, 12) has an associated valve member (16) interacting with an associated valve seat (17) in such a way as to form a valve device (16-18) defining a first orifice with a variable passage cross section between the inlet passage (7) and the outlet passage (18).