Patent GB-788980-A (GB)
Title: Hydraulic coffee machine with automatic control
IPC: A47J31/24
Filed: 1956-03-26
Abstract: 788,980. Beverage making machines. WURTTEMBERGISCHE METALLWARENFABRIK. March 26, 1956 [March 25, 1955], No. 9409/56. Class 129. [Also in Group XXIX] Hot water is drawn into the scalding chamber 7 of a coffee or like machine by a piston 2, biased to its filling position, which is operated hydraulically to force the water out through the coffee grounds or the like, the flow of pressure medium into the pressure chamber 8 of the hydraulic system from a pipe 39 and out through a pipe 34 being regulated by a control member 28 adjustable by a control piston 26 having a constant force operating on one side and on the other the pressure in chamber 25 which is connected permanently by an adjustable throttle member 38 to pipe 39 but may be connected by a hand-operated valve 31 to pipe 34. As shown, working piston 2, which operates in cylinder 1, is connected by a rod 5 to power piston 4 which operates in cylinder 3 coaxial with cylinder 1. Scalding chamber 7 is closed by a distributing sieve 9 under which a coffee sieve holder is releasably fixed, e.g. by a bayonet joint. Piston 4 is biased by a spring 11 which bears against a disc 12 arranged in a sleeve 13 surrounding rod 5 and fixed to an annular cylinder head 14. Piston 2 is hollow so that, as it rises, it accommodates the lower end of sleeve 13. The lower end of chamber 7 is connected via port 16, chamber 17, spring- biased valve 19 and port 18 with the water boiler. The stem 20 of valve 19 is engaged by the end of a pivoted lever 22 whose other end projects through a slot 23 in the wall of cylinder 1 so that it is rocked to open valve 19 as piston 2 rises and opens port 16 allowing water from the boiler to enter the scalding chamber. Control piston 26 slides in a cylinder bore 25, 25<SP>1</SP> and is connected by a rod 29 with a piston 28 sliding in a small bore 27 coaxial with bore 25, 251. The end 25<SP>1</SP> is connected by pipe 39 with a supply of water under pressure and, when piston 28 in in its rearmost position, through bore 27 with cylinder 8, the end 25 is connected by pipe 37 with an adjustable throttle valve 38 to pipe 39 and by pipe 30 through manually-operated valve 31 to the water boiler. When piston 28 is in its forwardmost position, cylinder 8 is connected via pipe 34 with the boiler. In use, a sieve of coffee is attached and the pistons and valves are in the positions shown in Fig. 1. Button 35 is pressed to open valve 31 which connects end 25 with the boiler, thus allowing piston 26 to move under the influence of the water under pressure from pipe 39. This causes piston 28 to move to its forwardmost position connecting cylinder 8 with the boiler so that it rises under the influence of spring 11 drawing hot water into the scalding chamber 7 from the boiler when valve 19 is opened. Valve 38 governs the time taken for cylinder 25 to fill up again with water under pressure which moves pistons 26 and 28 back to their original positions when the hot water is expelled from the scalding chamber through the coffee. A practical constructional form of the apparatus is illustrated in Figs. 3 and 4 (not shown).