Coffee Machine And Method For Preparing A Cup Of Coffee

A method for preparing a cup of coffee characterized in that it comprises the following steps:

• supplying a closing piston (8);
• supplying a movable infusion unit (3) beneath the closing piston (8), said infusion unit (3) comprising an infusion chamber (4) having an open access mouth (4c) facing said closing piston (8) and having an ejection piston (9) slidably supported in the infusion chamber (4).
• introducing a load of loose coffee grounds (32) into the open infusion chamber (4).
• subjecting said infusion unit (3) to a first course of translational movement towards said closing piston (8), said first course being of such an extent that the closing piston (8) closes the infusion chamber (4) as it penetrates therein;
• in the position of the infusion unit (3) thus achieved, sending a flow of water at a temperature ranging between 85° C. and 100° C. and a pressure level ranging between the atmospheric pressure and 2×105 Pa, into the closed infusion chamber (4) for execution of the infusion process;
• at the end of the infusion process, subjecting said infusion chamber (4) and said ejection piston (9), or only said ejection piston (9) to a second course of translational movement in the same direction as the first course of translational movement, said second course of translational movement being of such an extent that the closing piston (8) compresses the load of spent coffee grounds (33) for drainage of the liquid contained therein, as it penetrates further into the infusion chamber (4);
• at the end of the drainage process, opening infusion chamber (4) and extracting the dried load of spent coffee grounds (33).