Automatic coffee-making apparatus

Claim 1

A coffee-making apparatus of the kind comprising a casing connected to a source of hot pressurized water, a rotor supported and driven for step-by-step rotation, said casing having a coffee inlet, a beverage percolation outlet and a spent coffee discharge outlet, said rotor having a peripheral wall, diametrically arranged and oppositely located equal cavities opening on said peripheral wall and oppositely located pistons each slidable in one of said cavities, the casing comprising a finely perforated diaphragm at said percolation outlet facing a cavity aligned with said outlet, said rotor being intermitently rotated for sequentially carrying each cavity to a first station facing said coffee inlet, to a second station facing said percolation outlet and diaphragm, to a third station facing said discharge outlet and then again at the first station for cycle repetition, while the opposite cavity is concurrently carried to face said discharge outlet, wherein the improvement comprises an intermediate passage interconnecting said cavities and having its cross-sectional area less than that of said cavities, an intermediate component interconnecting said pistons sealingly slidable under the action of pressurized water in said intermediate passage, each piston dividing the cavity wherein it sealingly slides into an outer space open at said peripheral wall and an inner annular space defined by said intermediate component, a stepped rear face of the piston, the adjacent face portion of said intermediate passage and the wall of said cavity, the said rotor comprising duct means having their outlet in said annular space whereby hot pressurized water is supplied in said space at said percolation station to bias the piston toward said peripheral wall and compact an amount of fresh ground coffee under a give pressure between said piston and said perforated diaphragm, in said outer space.