Automatic coffee-making machine with direct-current motor drive and worm screws

Abstract: An automatic coffee-making machine comprising in combined form a drive unit consisting of a direct-current motor (14) to the shaft (14a) of which is made integral a worm screw (14b) capable of actuating, in an axial direction, the sealed rod (16a) of a valve body (16) and of engaging with means (13,12) for transmission of movement with a slider (4), capable of moving at right angles to the axis of rotation of motor shaft (14a), there being made integral with such slider (4), by means of appropriate couplings (5,5a,9a,10a) a shaped member (9) integral with the free end of the rod of piston (8), there being also provided means (15,20) for the ejection and removal of the spent powdered coffee, as well as means (114) for monitoring and controlling the power input to motor (14), this making it possible to determine in an automatic manner the instants of start and end of the strokes of piston (8) during the phases of downward movement, insertion in the filter-holder, compression of the powdered coffee, upward movement and lateral rotation for discharge.

Description: The object of this invention is an automatic machine for making, in the home or in public premises, a beverage based on water and coffee extract (hereinafter known simply as "coffee") either of the so-called espresso type or of the so-called American type. To prepare coffee, in particular espresso coffee, that is to say an infusion obtained with hot water under pressure and powdered coffee, use is made of different kinds of appliances, which provide in each case for water to be passed at high temperature, under sufficient pressure, through a layer of ground coffee of suitable particle size, the infusion so obtained then being drawn off. To obtain coffee of high quality it is desirable that the infusion water be at a temperature lower than boiling point, in order to avoid extracting from the coffee not only the aromatic constituents which impart flavour to the beverage, but also undesirable and often harmful constituents which only at temperatures approaching the boiling point of water are released from the powdered coffee. Widespread use is therefore made both in public premises and in private dwellings of appliances which, by supplying water through the powder without raising it to boiling point, make it possible to obtain such high-quality beverages. The automatic coffee-making machines provide for the powdered coffee to be placed in a filter-holder equipped with a filter to retain the powdered coffee and allow the infusion obtained to flow out, for the powder to be pressed with a piston to a suitable extent and for the supply via such piston of hot water under pressure to bring about infusion. Provision therefore needs to be made for a drive unit governing the insertion of the piston into the filter-holder and maintaining it in position while hot water is supplied under pressure. For this purpose use may be made of drives consisting of motor-reduction units of non-reversible type, but such motor-reduction units are expensive and do not prove suitable for a machine intended for domestic use. Example of prior art is disclosed into EP-A-0270141 in the name of the same applicant. Like problems arise with further devices responsible for operation, metering of water, control of cycle and so on, in attempting to obtain a compact machine for domestic use which will prove reliable and produce, in an automatic manner, coffee of equivalent quality to that of coffee made with the larger machines used in public premises and the like, while still keeping down the overall dimensions and costs. There is therefore posed the technical problem of developing a machine for making coffee either of the so-called "espresso" type or of the so-called "American" type, capable of carrying out in an automatic but controlled manner the entire sequence of operations involved and consisting of a limited number of parts, so as to be compact and take up little space. Such results are obtained with this invention according to the characterizing part of the main claim, which provides an automatic coffee-making machine comprising a cylinder, having at the bottom a moving filter for filtering the coffee infusion, into which can be inserted in a sealed manner a piston provided with means for supplying hot water under pressure obtained from a metering unit, in which provision is made for a drive unit formed by a direct-current motor to the shaft of which is made integral a worm screw capable of driving, in the axial direction, the sealed rod of a valve body, and of engaging, with means of transmission of movement, a slider moving at right angles to the axis of rotation of the motor shaft, there being made integral with such slider by means of appropriate couplings a shaped member integral with the free end of the piston rod, means also being provided for ejecting and removing the spent powdered coffee, as well as means for monitoring and controlling the power input to the motor so as to establish automatically the moments of commencement and end of the piston strokes during the phases of downward movement, insertion into the filter-holder, compression of the powdered coffee, upward movement and lateral rotation for removal. According to this invention provision is made for such means of transmission of movement of the direct-current motor shaft to consist preferably of a gearwheel of vertical axis in which is provided coaxially an internal screw designed to actuate a threaded shaft, to the upper end of which is made integral a slider and to the lower end of which, unthreaded and of smaller diameter, is made integral a circular member equipped in turn with an outward-projecting arm. More particularly, such means for controlling the machine cycle are substantially comprised of means for monitoring the overloads of the power input to the motor in relation to the positions of the upper end of stroke, determined by stoppage of the pin at the top of the helix of the circular member, and of the lower end of stroke, determined by the thickness of the measure of coffee or, in the event of lack of supply, by the striking of the arm against the lower end of the cavity. Furthermore in the automatic coffee-making machine according to the invention provision is made for means to supply water to the cylinder independently of the valve body, the machine cycle thus bringing about infusion by simple compression by the piston to produce so-called "American" coffee. Further details may be obtained from the following description with reference to the attached drawings, which show: In figure 1 : a partial sectional view of the machine according to the invention, drawn according to plotting plane I-I of fig. 2; In figure 2 : a sectional view according to plotting plane II-II of fig. 1; In figure 3 : a sectional view according to plotting plane III-III of fig. 1; In figs. 4a,4b,4c : partial sectional schematic views of the machine illustrating the various conditions during the cycle start-up phase; In figs. 5a,5b,5c : corresponding figures illustrating the phase of infusion of the coffee; In figure 6 : the machine in figure 5b during the initial part of the discharge phase; In figs. 7a,7b,7c : corresponding figures illustrating the final part of the discharge phase and commencement of disposal of the spent powder. As shown in figure 1, coffee machine 1 according to this invention consists of a supporting member 2 of substantially inverted "T" section on which are provided a circular seat 2a to accommodate reservoir 3 for the water, which is heated by means of element 3a; an open cavity 2b extending vertically throughout the length of the leg of the "T" and capable of guiding a slider 4, to which is made integral an upper arm 5 extending at right angles thereto and having free ends presenting an annular outlet 5a near to the relevant tip, which is itself shaped according to a truncated cone 5b. Such arm 5 can slide vertically and in a guided manner in a slot 1c provided in wall 1 of the machine. On the arm of the "T" opposite that supporting water reservoir 3 is provided a second seat 2d of forked shape for the quick attachment and accommodation of cylinder 6 into which is fed the powdered coffee (6a) which settles at the bottom on a flat filter 7, capable of being operated in a vertical sense by a rod 7a against the reaction exerted by a spring 7b coaxial with such rod, against an end piece 7c of rod 7a and against the lower surface of the bottom wall of cylinder 7. The predetermined measures of powdered coffee 6a, supplied in a known manner and therefore not described in detail, are compressed within cylinder 6 by a piston 8, provided with means 8a for annular sealing, rod 8b of which is integral at its upper end with a member 9 shaped in such a way as to present a first cavity 9a, coaxial with rod 8b of piston 8 and capable of accommodating a spring 10 exerting thrust in a radial sense on a sphere 10a of diameter such as to enable it to be retained by outlet 5a of arm 5, to bring about the rotary coupling of shaped member 9 and therefore of piston assembly 8 to arm 5, the free end 5a of which is housed in a further cavity 9b located at right angles to the former. Shaped member 9 also has an appendage 9c projecting transversally towards the vertical leg of the "T" and capable of being inserted into a cavity 11a of a plate 11, which in turn is hinged to pin 11b (fig. 4a) around which it can rotate, such cavity 11a having an upper end shaped according to an eyelet 11c. To plate 11 is also made integral a blade 20 the upper end of which is pushed downward by a spring 20a housed in a corresponding seat 20b, such blade being arranged to slide on the upper free surface of cylinder 8 in order to effect the removal of the powder at the end of the cycle, the variations in length due to rotation of plate 11 being compensated by corresponding variations in the extension of spring 20a. The operation of slider 4 with its arm 5 and piston 8 according to the machine cycle is achieved by means of a threaded shaft 12 having its upper end integral with slider 4, which is actuated by an internal screw 13a of a gearwheel 13 the outer teeth 13b of which are meshed with a worm screw 14b located at right angles to the axis of rotation of shaft 12 and moved by a shaft 14a of a direct-current motor 14 coaxial thereto, provided with appropriate electronic or like means for controlling the power input and for programming the phases of the machine cycle, which are known in themselves and are therefore only illustrated diagrammatically by outline 114. Such gear 13 is located in a seat 21 integral with support 2 and forming a vertical shell 21a performing a dual role as a guide for shaft 12 and as a mechanical limit switch for a circular member 15, inserted at the lower end 12b of shaft 12. Such lower end of shaft 12 is not threaded and has a smaller diameter than that of the threaded part, so that circular member 15 may be made to strike the end part of such threaded portion by the thrust exerted by a spring 15b located coaxially with shaft 12 and respectively striking the lower surface of circular member 15 and a disc 12a integral with shaft 12 of the other. Circular member 15 is provided externally with a projecting arm 15b capable of coming into contact, during a phase of the machine cycle, with the lower end of rod 7a in relation to which it is normally kept in line by the return action of a spring 30; inside such circular member 15 is furthermore provided a spiral 15c coaxial with shaft 12, on which can be caused to react a pin 12c made transversally integral with shaft 12, as will be more clearly described hereinafter with reference to the operation of the machine. The machine operating mechanism is completed by a valve body 16 having two chambers, the first 16a of which is provided with two openings, a one for the sampling of water according to arrow P and another for supplying cylinder 6 according to arrow A, the second chamber 16b being provided with an opening to discharge the liquid according to arrow S; such chambers are placed in communication with one another by a duct 16c which can be opened and closed by means of a sealed rod 16d operated transversally by a pin 14c integral with shaft 14a of motor 14, acting against the force exerted by a spring 16e. The operation of the machine is as follows : at the commencement of the cycle (figs. 4a,4b,4c) slider 4 is at the top and therefore piston 8 is raised, plate 11 is rolled outward, filter 7 is at the bottom of cylinder 6 and circular member 15 is striking against shell 21a with pin 12c inserted, at the end of the stroke, in spiral 12c, so that arm 15b is rolled into a position out of line in relation to rod 7a of filter 7; sealed rod 16d of valve 16 is drawn outward. When the cycle is started by coin operation or pushbutton control the predetermined measure of coffee 6a is supplied to cylinder 6, powered by motor 14 which begins to drive its shaft 14a, gearwheel 13 being operated in a direction such as to cause the rotation of shaft 12 so as to bring about the downward movement of slider 4, and therefore of piston 8 and circular member 15, with the corresponding downward movement of pin 12c which, on disengaging spiral 15c, allows spring 30 to return arm 15b which ends up in a lower position relative to rod 7a. At the same time motor shaft 14a pushes sealed rod 16d to the bottom of its stroke, thus sealing off passage 16c and placing duct P, which samples the liquid in boiler 3, in contact with duct A supplying the liquid to cylinder 6 in which it flows under pressure through coffee measure 6a to produce the infusion, which is delivered via outlet duct C. Following delivery, a new command to motor 14 brings about the reversal of rotation of the latter so as initially to return rod 16d of valve 16 and open communication duct 16c, which allows return R of the residual pressure remaining in the cylinder for rapid discharge via port S; there is then reversed the rotation of shaft 12 (fig. 6) which starts to rise carrying with it circular member 15, arm 15b of which lifts up rod 7a of filter 7 which, on rising, conveys to the free rim of cylinder 6 the spent measure of coffee. During such movement (figs. 7a,7b,7c) member 15 strikes shell 21a against which it stops, while shaft 12 continues to rise until arm 5 of slider 4 reaches the upper end of cavity 11a against the shaped top of which it begins to exert pressure, forcing plate 11 to rotate around pin 11b carrying with it blade 20 which, under the thrust exerted by spring 20a, is maintained in contact with the edge of cylinder 6, thus bringing about the removal of the spent measure of coffee. Simultaneously with shaft 12 there also rises pin 12c which, together with spiral 15c, engages the latter, raising it up to the top end of stroke and causing the rotation of arm 15b with the consequent disengagement of the latter from the lower end of rod 7 which, under the return movement of spring 7b, recovers its initial setting and conveys filter 7 to the bottom of the cylinder; the machine thus resumes its initial configuration (figs. 4a,4b,4c) and is ready for a new cycle. In particular, it is possible with such configuration to achieve a so-called "American" coffee infusion, which is done by simple compression without overpressure; in this case there is supplied a predetermined measure of coffee, smaller than the normal quantity used for espresso coffee, the remaining space in cylinder 6 being filled with water; at this point the normal machine cycle commences, but without the supply of further water under pressure, so that the coffee infusion is obtained solely by the pressure exerted by the downward movement of piston 8 in cylinder 6. It should also be noted that with a machine configuration according to this invention it has been possible to eliminate all the electromechanical limit switches necessary to establish the beginning and end of the various phases of the machine cycle; thus, by using means of control connected to the direct-current motor it is possible to establish, by monitoring the overload of power input to the said motor, the two moments of end of stroke brought about during downward movement by the resistance exerted by the measure of coffee to the thrust action of the piston, such resistance being proportional to the thickness of the said measure, and during upward movement by the resistance obtained by the locking of pin 12c which has raised spiral 15c to the end of the stroke. It is also possible, by calibrating such power input to motor 14, to predetermine the pressing of coffee measure 6a, or conversely to bring about any change in the thickness thereof due to malfunction of the supply system. Many alternatives may be introduced without thereby departing from the scope of the invention in regard to its general features.

Claims: An automatic coffee-making machine of the type comprising one cylinder (6), having at the bottom a moving filter (7) for filtering the coffee infusion (6a), in which can be inserted in a sealed manner a piston (8) provided with means for supplying hot water under pressure, obtained from a metering unit, a drive unit consisting of a motor (14) and means (15, 20) for the ejection and removal of the spent powdered coffee characterized in that said motor is a direct-current motor (14) to the shaft (14a) of which is made integral a worm screw (14b) capable of actuating, in an axial direction, the sealed rod (16a) of a valve body (16) and of engaging with means (13,12) for transmission of movement with a slider (4), capable of moving at right angles to the axis of rotation of motor shaft (14a), there being made integral with such slider (4), by means of appropriate couplings (5,5a,9a,10a) a shaped member (9) integral with the free end of the rod of piston (8), as well as means (114) for monitoring and controlling the power input to motor (14), thus making it possible to determine in an automatic manner the moments of commencement and end of the strokes of piston (8) during the phases of downward movement, insertion in the filter-holder, compression of the powdered coffee, upward movement and lateral rotation for discharge. An automatic coffee-making machine according to claim 1 characterized in that such means of transmission of the movement of shaft (14a) of direct-current motor (14) are preferably comprised of a gearwheel (13) of vertical axis in which is provided coaxially an internal screw capable of actuating a threaded shaft (12) to the upper end of which is made integral a slider (4) and to the lower end of which, unthreaded and of smaller diameter, is made integral a circular member (15). An automatic coffee-making machine according to claim 1 characterized in that the means of transmission are housed in a seat (21) provided with an extension forming a vertical shell (21a) guiding shaft (12) and marking the end of stroke for circular member (15). An automatic coffee-making machine according to claim 1 characterized in that such circular member (15) has an arm (15b) projecting outward and capable of actuating transversally the supporting rod of filter (7) against the action of spring (7b), and an internal spiral (15c) located coaxially with shaft (12) and capable of reacting in conjunction with a pin (12c) made transversally integral with shaft (12) in position within such circular member (15) in order to bring about the rotation of the circular member against the return action of springs (30) made integral therewith. An automatic coffee-making machine according to claim 1 characterized in that such shaped body (9) has a pair of cavities (9b,9a) located at right angles to one another and respectively capable of accommodating the free end of an arm (5), integral at right angles with slider (4), and a spherical member (10a) actuated by the thrust action of springs (9a) capable of achieving locking of arm (5) inside such cavity (9b), such shaped body (9) being furthermore provided with an arm (9c) projecting into the machine and capable of sliding in the corresponding cavity of a plate (11) which can be caused to rotate around a pin (11b). An automatic coffee-making machine according to claim 1 characterized in that such valve body (16) has a pair of chambers (16a,16b) interconnected with one another via a port (16c) which can be opened and closed by the alternating stroke of sealed rod (16), a first chamber (16a) enabling sampling (P) of the water and supply (A) thereof to piston (8), and a second chamber enabling, when in contact with the former, rapid discharge (S) of the residual pressure (R) within cylinder (6). An automatic coffee-making machine according to claim 1 characterized in that such means of control of the machine cycle are substantially comprised of means for monitoring the overload of the power input to the motor in relation to positions of the upper end of stroke, determined by the stoppage of pin (12c) at the top of helix (15c) and of the lower end of stroke, determined by the thickness of coffee measure (6a) or, in the event of lack of supply, by the striking of arm (9c) against the lower end of such cavity (11a). An automatic coffee-making machine according to claim 1 characterized in that means are provided to supply water to cylinder (6) independently of valve body (16), the machine cycle thus bringing about infusion by simple compression by piston (8) to produce so-called "American" coffee. An automatic coffee-making machine according to claim 1 characterized in that such means for disposing of the spent coffee dose are substantially comprised of a blade (20) integral with rotary plate (11) with which it rotates to the end of the cycle sliding on the upper free edge of cylinder (6), the variations in length due to rotation being compensated by matching variations in the extension of spring (20a) integral with plate (11) and acting on the upper part of blade (20).

Inventors: GROSSI LUCIO, GROSSI, LUCIO
Applicants: GROSSI LUCIO, GROSSI, LUCIO
Application year: 1992
Main classification: A47J31
IPC codes: A47J31