GB971767A - - Google Patents

Abstract

971,767. Coffee-making machines. INVENTION & RESEARCH S.A. Nov. 13, 1961 [Nov. 14, 1960], No. 40561/61. Heading A4D. In a coffee making machine of the type in which hot water is displaced from a cylinder by a piston so as to force the water through coffee contained in a filter, the piston is moved downwardly against the action of a return spring by a compressed fluid, e.g. air, but before the piston moves the cylinder and the filter are moved axially relatively to one another so that the bottom of the cylinder enters the filter to compress the coffee. Such axial movement may also be by means of compressed fluid, or it may be by a cam action, in which case either the cylinder may be moved down into the filter or the filter may be moved up against the cylinder end. The Figures show an example worked wholly by compressed air, Fig. 1 showing the inoperative and Fig. 2 the operative coffee-making position. Fixed to the water-boiler 18 are top and bottom flanged members 3, 4, spaced by tie rods 6, in which slides a cylinder 7 by means of a fixed cap 4 at its upper end and a projection 9<SP>1</SP> of reduced diameter at its lower end, the cylinder being urged upwards to the inoperative position by compression spring 27. The cylindrical projection 9<SP>1</SP> can enter the detachable filter 21 containing ground coffee. Within the cylinder is a piston 14 urged upwardly by compression spring 15 and fixed to its crown is a cylindrical member 23 having a closed axial bore 24 communicating with upper and lower transverse bores 25, 26. In use the container 18 contains hot water which also fills the inside the cylinder 7. Compressed air is introduced at inlet 28 into space 4 above the cylinder cap 8. This forces down the cylinder assembly until its lower end 9<SP>1</SP> compresses the ground coffee in filter 21 and the parts are as in Fig. 12. Compressed air can then pass through passage 25, 24, 26 into the cylinder above the piston 14 whereupon the piston is pressed down to force water through check valve 11, orifice 12, through the ground coffee and discharge nozzles. When the compressed air is vented to atmosphere the parts return to the position shown in Fig. 1 and as the piston rises it draws in water through check valve 13 to refill the cylinder. The machine accepts fine or coarse ground coffee without affecting its timecycle. Thus if the coffee is very finely ground and packs down under pressure, so offering undue resistance to the passage therethrough of the hot water, the build up in pressure immediately above filter disc 29 causes the lower end 9<SP>1</SP> of the cylinder to lift and so allow the ground coffee to expand.