COMPACT AUTOMATIC COFFEE-MAKING MACHINE MORE PARTICULARLY FOR DOMESTIC USE

Abstract: The automatic coffee-making machine according to the invention comprises a filter carrier (3) having on its base a movable filter (6) for filtering the coffee infusion, there being introducible into the carrier in sealing-tight manner a piston (14) having means for delivering pressurized hot water supplied by a metering unit, the piston being operated for its movements of descent, introduction into the filter carrier element, compression of the coffee powder, raising and lateral rotation by a rod (17) having resilient piston-pulling means (21) and connected to a rotating disc (19) actuated by a geared motor (20), means (10-13) being provided to support and guide the piston in its movement, the latter means providing an irreversible transmission of the movement from the motor to the piston, automatic means (25, 30 32, 33) being provided to expel the spent coffee powder and to supply fresh powder to the filter carrier.

Description: This invention relates to an automatic coffee-making machine, more particularly for domestic use. Various kinds of apparatus are used for preparing coffee, more particularly espresso coffee - i.e., an infusion produced with hot water and coffee powder - and in all of them water at a high temperature and an appropriate pressure through a layer of coffee powder, the resulting infusion then being collected. To produce a high-quality coffee the infusion water must be at a temperature below boiling point in order to obviate removing from the coffee powder not only the aromatic ingredients which give the beverage its taste but also undesirable and in some cases harmful ingredients which are evolved from the coffee powder only at temperature above the boiling point of water. Consequently, apparatuses in which water passes through the coffee powder at a temperature below boiling point and which therefore yield a high-quality product are very widely used both commercially and privately. More particularly, for domestic use a compact and low-cost coffee-making machine is required. In automatic coffee-making machines the coffee powder is disposed in a filter carrier having a filter for retaining the coffee powder and discharging the infusion produced, a piston compresses the powder to an appropriate extent and hot water is supplied by way of the piston to produce the infusion. A driving element is therefore necessary to introduce the piston into the filter carrier and to retain the piston thus positioned while hot pressurized water is supplied. In particular, in order to make a good coffee, it is necessary to compress for a correct amount the coffee powder and then maintain the compression during the water delivery. The known machines, such as EP-A-O 117 583 (GASPARELLA) and FR-A-2 562 782 (NUOVA BIANCHI), have an actuating device for the piston which has a fixed stroke, so that the piston reaches always the same position in the filter carrier during the delivery of the water under pressure: this involves that in order to obtain a constant value of the compression of the coffee powder a perfect metering of the amount of coffee powder must be done, to get a constant level in the filter carrier. Therefore the problem arises to get a constant force of compression of the coffee powder, independently from the precision of its metering, and to keep such compression force constant during the whole cycle of delivering of the hot water for the infusion, keeping constant the position of the piston in the filter carrier. Operating units using irreversible geared motors can be used for this purpose but such devices are expensive and are unsuitable for a domestic machine. Similar problems arise in connection with the other operating steps required, such as metering of the water, control of the cycle and so on, to produce a compact domestic machine which is reliable and which automatically produces a coffee of the same quality as the coffee produced by the larger machines used commercially but which is still compact and cheap. These results are provided by this invention; the same provides an automatic coffee-making machine comprising a filter carrier in which a piston is introducible in sealing-tight manner, said piston having means for delivering pressurized hot water and being operatively connected, for its movements of descent, introduction into the filter carrier element, compression of the coffee powder, raising and lateral rotation, to a rotating element actuated by a geared motor by means of a rod, means being provided to support and guide the piston in its movements, characterized in that the rod connecting the piston to the rotating element has resilient pulling means, said rotating element being a disc, the support and guide means providing an irreversible transmission of the movement from the motor to the piston, the resilient pulling means consisting in a rod connected at one end to a pin of the disc and formed at the opposite end with a slot whose axis is aligned with the pin and in which a bar, carrying the piston, is introduced, the slot bottom edge acting on the bar for the rising movement of the piston, a resilient means further connecting the bar to the disc pin, said resilient means causing the descent of the piston, with the bar sliding in the slot, with a force substantially independent of variations in the thickness and resistance of the powder to be compressed, a plate being further provided, rockingly mounted on a casing laterally of the direction of bar movement, having a slot in which the piston carrying bar is slidably inserted, the top of the slot being at a level below the maximum lift of the piston, the plate rotating around its own support pin during the rising movement of the piston when the bar contacts the slots apex, means being provided rotatingly connecting the piston-carrying bar and the plate, so causing a lateral inclination of the piston at the top of its raising movement. The means for supporting and guiding the piston in its movement take the form of a vertical upright disposed on the machine casing, a sleeve being slidable on the upright and carrying transversely a horizontal rod to whose end the piston is attached, the distance between the place at which the piston is attached to the horizontal rod and the sleeve being greater than the length thereof so that a vertical force exerted on the piston causes the sleeve to be clamped fast to the upright. The rod and the resilient piston-pulling means are connected to the horizontal rod supporting the piston at a short distance from the sleeve so that the forces exerted on the rod by the last-mentioned means do not clamp the sleeve to the upright. A spatula for removing spent coffee powder and a guide chute for introducing fresh powder into the filter-carrying element are secured to the rocking plate, the spatula and chute rocking with the plate at the top of the rising movement of the piston. The moving filter in the filter carrier can be raised, by way of mechanical transmission elements associated with the piston-carrying rod, as far as the top edge of the filter carrier, the filter carrying the spent filter powder above it in such movement into a position in which the powder can be removed by the spatula. The unit metering the infusion water comprises a water-collecting reservoir connected by way of an automatic shut-off valve to a bellows tank whose volume can be varied to suit the dose for a coffee or of a number of coffees in the case of a multiple machine, the bellows tank being connected to a pump supplying the water to a heating unit and therefrom to the piston. The line from the pump to the heating unit also comprises an automatic valve for placing the piston on discharge; the automatic shutoff valves of the line feeding the bellows tank and for placing the piston on discharge are activated by transmission means associated with a lever operated by a camming profile on the disc rotated by the geared motor. Conveniently, the bellows tank has a float associated with an electric sensor adapted to stop the pump upon the bellows tank emptying. The rotating disc driven by the geared motor and producing the piston movements also has a number of cams associated with electrical switches initiating the consecutive operating phases of the machine during one complete revolution of the disc. Conveniently, the water flow passages in the piston and filter can be in the form of annular flow passages bound by elements performing a relative movement in every cycle in order to remove any deposits in the passages. The machine according to the invention has provision for metering the coffee powder supplied to the filter carrier at every cycle; such provision for metering the coffee powder can be associated with a coffee grinder. Further details can be gathered from the following description, reference being made to the accompanying drawings, wherein: Fig. 1 is a longitudinal section through the machine according to the invention on the line I-I of Fig. 2; Fig. 2 is a front view of the machine of Fig. 1; Fig. 3 shows the water circuit of the machine; Fig. 4 is a diagrammatic section on the line IV-IV of Fig. 1; Fig. 5 is a section on the line V-V of Fig. 1; Fig. 6 is a front view of the machine of Fig. 1 in the open phase, and Fig. 7 is a front view of the machine of Fig. 1 in the phase of expelling the spent charge of coffee and of loading fresh coffee powder. The machine according to the invention mainly comprises an outer casing 1; secured thereto is a support 2 which receives a filter carrier 3 formed with an internal recess 4 adapted to receive coffee powder 5, the recess 4 being bounded at the bottom by a blind filter 6 having a pin 7 slidable in the filter carrier 3 and retained in the lowered position by a spring 8. The casing 1 has an inner wall 9 carrying an upright 10 on which a sleeve 11 can slide. The sleeve 11 has a cross-tube 12 receiving a rod 13; secured to the end thereof is a piston 14 introducible in sealing-tight manner into the filter carrier recess 4; the rod 3 is freely rotatable in the tube 12 and is secured axially internally by a pin 15. The tube 12 is engaged in a slot-like aperture 16 in a rod 17 whose bottom end is engaged on a pin 18 of a cam disc 19 rigidly secured to the output shaft of a geared motor 20; the tube 12 is also secured to the pin 18 by way of a spring 21 and respective brackets 22, 23. As is also shown in Fig. 2, the rod 13 is slidingly engaged in a shaped slot 24 in a plate 25 rotatable around a pin 26; a bent member 27 is also disposed in the slot 24 and provides a connection in rotation between the rod 13, the piston 14 attached thereto and the plate 25. The plate is also formed with a recess 28 in which a blade 29 engages, the blade 29 being carried by an arm 30 rotatable around a pin 31; by way of a link 32 the plate 25 is connected to a chute 33 rockingly mounted on a pin 34 carried by a lateral part (not shown) of the structure. As can be gathered from Fig. 4, a slider 35 is also engaged on the rod 13; it is formed with a slot 36 through which the rod 13 extends and has at its bottom end a projecting pin 37, the same projecting outside the casing I through a shaped aperture 38, the contour of which is indicated in Fig. 2 in solid line and in Fig. 4 in chain-dotted line. A plate 39 also engaged on the rod 13 bears on the slider 35 and is connected thereto by way of a spring 40 attached at one end to a pin 41 projecting from plate 39 and at its opposite end to a bent strip 42 of the slider 35, the spring 40 extending through the plate 39 by way of slot 43 therein and thus ensuring that the plate 39 and slider 35 are always in a position of alignment. The support 2 receives internally electrical resistances 43 which extend at least to some extent around the filter carrier 3 and a heating chamber 14 is placed in contact with the support 2, the chamber 44 having an internal cavity 45 having an inlet duct 46 and an outlet duct 47. The outlet duct 47 extends to the piston 14 where it is connected to an internal duct 48 which, by way of a calibrated aperture having a moving internal element 49, extends to a blind filter 50 having a sliding closure member 51. Internal ducts 52 supply pressurized water rearwardly of a ring gasket 53 to thrust the same radially on to the inner wall of the cavity 4 and thus make the piston 14 sealing-tight. The water supply circuit of the machine according to the invention is shown diagrammatically in Fig. 3 and comprises a water-collecting reservoir or tank 54 whence a flexible line 55 extends, by way of a valve 56 adapted to deform the line 55 until completely closing it through the agency of a spring 57, to a bellows tank 58 having a float level detector 59; a line 60 extends from the tank 58 to a pump 61 whose discharge line 62 is connected to a discharge valve 63 and therefrom to the line 46 feeding the heating chamber 44. The cam disc 19 has two profiles 64, 65; the front profile 64 has a projection 66 adapted to engage with a cam 67 rotatable around the pin 68 and maintained in contact with the profile 64 of a spring 69 stronger than the spring 57; the cam 67 is connected to the valve 56 by way of a transmission rod 70. The discharge valve 63 has a sliding lid 71 introducible in the gasket 72 to close the passage towards discharge line 73; a spring 74 maintains the lid 71 in contact with the cam 67. The reservoir 58 has a capillary duct 75 which extends to the level of the tank 54; by means of a knob 76 connected to a rotating cam profile 77, the volume of the bellows tank 58 can be varied by compressing the same to various extents. Cam profile 65 is associated with a lever 78 acting on a switch 79; the further cam profile 80 rigidly secured to the shaft of the geared motor 20 is in turn associated with a lever 81 acting on an associated switch; such switches initiate the consecutive operating phases for preparing coffee during one complete revolution of the geared motor. At the start of the working cycle of the machine, the cam disc 19 is disposed with the pin 18 in its top position; correspondingly, the valves 56, 63 are open and the piston 14 is in the raised position shown in Fig. 6 with the spent coffee charge 5 raised on the filter 6 outside the cavity 4. When the machine starts the piston 14 rises further until reaching a position in which the rod 13 strikes the top end of the slot 24 to rotate the plate 25 around the pin 26; through the agency of the bent member 27 the piston 14 is rotated and opens the mouthpiece of the cavity 4, the spent coffee charge 5 simultaneously being removed by means of spatula 29, as shown in chain-dotted line in Fig. 7. At the highest point of the rising movement of the rod 13, together with the rotation of the plate 25 and of the arm 30 carrying the blade 29, lateral ridge 82 of plate 39 which slides relatively to the slider 35, the same having been locked upon the complete rising of the rod 7, strikes a stationary abutment 83 and the plate 39 and slider 35 rotate through a reduced angle causing the pin 37 to disengage from the rod 7 so that the filter 6 can return to its lowered position through the agency of the spring 8 while the pin 37 can then rotate into its bottom position during the descent of the rod 13 by sliding in the slot 38 laterally of the rod 7. A metering and grinding facility associated with the machine but not shown and possibly of known kind supplies coffee powder by way of the chute 33 to the cavity 4. Subsequent rotation of the motor rotates the cam disc 19 in the direction indicated by an arrow F in Fig. 3 and so the pin 18 descends and acts by way of the spring 21 to lower the rod 13; the same slides in the slot 24 in the plate 25 rotates the same so that the piston 14 takes up a vertical position and the spatula 29 retracts. Continuing its downwards movement under the influence of the spring 21 the piston 14 engages in the recess or cavity 4 and compresses the coffee powder therein at a pressure which depends upon the stiffness of the particular spring 21 used and which is very little influenced by the quantity of powder metered, the percentage elongation variation of the spring arising in compression of different powder dosages being slight. Independent movement of the rod 13 and rod 17 is ensured by the sliding of the rod 17 in the slot 16. By way of the valve 56 which stays open the bellows tank 58 is kept full from the tank 54, water rising through the capillary duct 75 to the level of the exposed surface in the tank 54; consequently, water dosage is relatively accurate and is affected only by the variation of the level reached in the capillary 75 and by the very reduced volume thereof due to the level variations in the tank 54; also, water dosage can readily be altered by varying the volume of the bellows 58 by means of the cam disc 77. Upon completion of rotation of the cam disc 19, corresponding to complete compression of the coffee powder 5 in the filter carrier 3, the disc 19 is stopped by switch 79 in the position shown in Fig. 3, lever 78 of switch 79 engaging in notch 78a in cam profile 65. The pin 18 has therefore been rotated through a few degrees, in the direction indicated by the arrow F, to before the bottom dead centre position; in this position the spring 21, which is extended to compress the coffee powder and which is operative upwardly, tends to rotate the cam disc 19 against the direction indicated by the arrow F; this rotation is opposed by the lever 78 which is engaged in the notch 78a in the member 65 so as to maintain the position of the disc 19 without transmitting forces to the geared motor 20. With the disc 19 in its blocked position the valve 56 is closed because of the rotation of the cam 67 caused by the projecting 66, the discharge valve 63 also closes and the machine is ready to supply the coffee. The switches associated with the movement of the cam disc 19 control the starting of the pump 61; the same is, conveniently, of the vibratory kind and supplies the water in the bellows 58 to the heater 44 and therefrom through duct 47 to the inside of the piston 14. The pressure of the hot water supplied therefore reduces the efflux through the calibrated aperture 49 and moves the central mobile element thereof axially, the sliding movement of the mobile element preventing the formation of deposits of scale on the seat, and water is supplied to the pressed coffee powder through the blind filter 50, the same being formed with an annular slow aperture in which a lid 51 is slidable with a clearance determining the actual size of the passage. The piston is therefore retained in position by the supply pressure of the water without any need for the geared motor 20 to be oversized for this reason since the thrust produced by the pressure is exerted on the rod 13 with a leverage considerably greater, for example, three times as great, as the guide length of the sleeve 11 on the upright 10. The sleeve 11 is then blocked because of the thrust exerted on the end of the rod 13 and so the piston position is retained without the geared motor having to perform this function; consequently, the geared motor 20 can be dimensioned without having to withstand stressing due to retaining the position and so costs considerably less. The pressure in the cavity 4 always produces a slight yielding of the piston 14 due to the take-up of clearances and to the resilient deformation under load of the rod 13; the resulting rearward movement of the piston 14 leads to a gap arising between the surface of the filter 50 and the coffee powder, such gap conveniently being at most 1 mm. The gap is advantageous since it helps to provide complete and uniform distribution of the pressurized water on the coffee with optimum effects over the entire surface. This therefore leads advantageously to an effective use of "blind filters" formed with a single flow aperture in which a mobile element is engaged slidingly, as described in detail in the Applicant's earlier patent No. 24 844 A/81 as regards both the bottom filter, through which the coffee produced passes, and as regards the top filter disposed on the piston and serving to distribute the waste over the surface of the coffee powder, thus leading to the flow passage always being kept free of scale or coffee residues while ensuring that the flow of water engages all the powder and does not leave dead unirrigated zones. Conventional perforate filters can be used instead of filters according to the patent application No. 24 844 A/81 referred to. The coffee then goes through the filter 6 and is collected inside the filter carrier 3 from which it issues through a spout 84; a sensor 85 associated with the float 59 stops the pump 61 when the bellows tank 58 empties. The cam disc 19 therefore completes its rotation, produced by the geared motor 20, raising the rod 13 and the piston 14; this raising, with the sleeve 11 sliding on the upright 10, can occur in this case with a reduced force since the distance between the point at which the rod 17 acts on the cross-tube 12 from the upright 10 is less than the guide length of the sleeve 11 on the upright 10 or is in any case such as not to cause any blocking. The piston 14 is then withdrawn from the cavity 4 and raised until it is near the position in which the rod 13 abuts the top end of the slot 24, the piston 14 then being locked in such position. As the rod 13 rises it draws with it the slider 35 and plate 39 and, through the agency of the pin 37 in engagement with the rod 7, raises the blind filter 6 and expels the spent charge of coffee powder 5 from the cavity 4. When the cam disc 19 has rotated past the position in which the part 66 abuts the lever 67, the same, as previously stated, is rotated by the spring 69; this movement allows the lid 71 of the valve 63 to move, such lid moving rearwardly and placing the piston 14 and the line 62 on discharge before raising the piston 14, thus enabling the sleeve 11 to disengage from its clamped position produced by the forces rising because of the pressure, so that the sleeve 11 can then slide readily along the upright 10. The machine according to the invention therefore provides reliable operation in a very simple and low-cost construction, more particularly with the possibility of the piston being pressed against the coffee powder and the hot pressurized water being supplied in the correct position without the need for any powerful actuating elements. The machine also ensures that the compression of the coffee powder is substantially constant and independent of the actual powder dosage, the compression being determined by the resilient restoring force of the spring 21 which is affected little by minor percentage variations of the extension of the spring 21 and which is unaffected by a fixed travel of the compressing piston. Another advantage is the provision of a very simple and efficient water-metering circuit using a reduced number of cheap components. This combination of features together with the reduced dimensions and the high reliability makes the machine particularly suitable for family use. Those parts of the machine which relate to cycle control, coffee supply and distribution and so on can be of known kind and have therefore not been described in detail.

Claims: An automatic coffee-making machine, comprising a filter carrier (3) in which a piston (14) is introducible in sealing-tight manner, said piston having means for delivering pressurized hot water supplied by a metering unit and being operatively connected, for its movements of descent, introduction into the filter carrier element, compression of the coffee powder, raising and lateral rotation, to a rotating element actuated by a geared motor (20) by means of a rod (17), means being provided to support and guide the piston in its movements, characterized in that the rod connecting the piston to the rotating element has resilient pulling means, said rotating element being a disc (19), the support and guide means providing an irreversible transmission of the movement from the motor to the piston, the resilient pulling means consisting in a rod connected at one end to a pin (18) the disc (19) and formed at the opposite end with a slot (16) whose axis is aligned with the pin and in which a bar (13), carrying the piston (14), is introduced, the slot bottom edge acting on the bar (13) for the rising movement of the piston, a resilient means (21) further connecting the bar (13) to the disc pin (18), said resilient means causing the descent of the piston, with the bar sliding in the slot, with a force substantially independent of variations in the thickness and resistance of the powder to be compressed, a plate (25) being further provided, rockingly mounted on a casing (1) laterally of the direction of bar movement, having a slot (24) in which the piston carrying bar (13) is slidably inserted, the top of the slot being at a level below the maximum lift of the piston, the plate (25) rotating around its own support pin (6) during the rising movement of the piston (14) when the bar (13) contacts the slots apex, means (27) being provided rotatingly connecting the piston-carrying bar (13) and the plate (25) , so causing a lateral inclination of the piston at the top of its raising movement. A machine according to claim 1, characterised in that the means for supporting and guiding the piston in its movement take the form of a vertical upright (10) disposed on the machine casing (1), a sleeve (11) being slidable on the upright and carrying transversely a horizontal bar (13) to whose end the piston (14) is attached, the distance between the place at which the piston is attached to the horizontal bar and the sleeve being greater than the lenght thereof so that a vertical force exerted on the piston causes the sleeve to be clamped fast to the upright. A machine according to claims 1 and 2, characterised in that the rod (17) and the resilient piston-pulling means (21) are connected to the horizontal bar (13) supporting the piston (14) at a short distance from the sleeve (11) so that the forces exerted on the horizontal rod (13) by the last-mentioned means (17, 21) do not clamp the sleeve (11) to the upright (10). A machine according to claim 3, characterised in that a spatula (29) for removing spent coffee powder and a guide chute (33) for introducing fresh powder into the filter-carrying element (3) are secured to the rocking plate (25), the spatula and chute rocking with the plate at the top of the rising movement of the piston. A machine according to claims 1 and 4, characterised in that the moving filter (6) in the filter carrier (3) can be raised, by way of mechanical transmission elements (35, 37) associated with the piston-carrying bar (13), as far as the top edge of the filter carrier, the filter carrying the spent filter powder above it in such movement into a position in which the powder can be removed by the spatula (29). A machine according to claim 1, characterised in that the unit metering the infusion water comprises a water-collecting reservoir (54) connected by way of an automatic shut-off valve (56) to a bellows tank (58) whose volume can be varied to suit the dose for a coffee or of a number of coffees in the case of a multiple machine, the bellows tank being connected to a pump (61) supplying the water to a heating unit (44) and therefrom to the piston (14). A machine according to claim 6, characterised in that the line from the pump to the heating unit (44) comprises an automatic valve (63) for placing the piston on discharge. A machine according to claims 1, 6 and 7, characterised in that the automatic shutoff valves of the line feeding the bellows tank (58) and for placing the piston on discharge (56, 63) are activated by transmission means (70, 71) associated with a lever (67) operated by a camming profile (66) on the disc (19) rotated by the geared motor (20). A machine according to claim 6, characterised in that the bellows tank (58) has a float (85) associated with an electric sensor (59) adapted to stop the pump (61) upon the bellows tank emptying. A machine according to claim 1, characterised in that the rotating disc (19) has a number of cams (65, 80) associated with electrical switches (79) initiating the consecutive operating phases of the machine during one complete revolution of the disc. A machine according to claim 1, characterised in that the water flow passages in the piston and filter are in the form of annular flow passages bound by elements (6, 51) performing a relative movement in every circle in order to remove any deposits in the passages. A machine according to claim 1, characterised in that it has provision for metering the coffee powder supplied to the filter carrier at every cycle. A machine according to claim 12, characterised in that the provision for metering the coffee powder is associated with the coffee grinder.

Inventors: GROSSI, LUCIO
Applicants: GROSSI, LUCIO
Application year: 1987
Main classification: A47J31
IPC codes: A47J31