MX2008006474A - Device for producing coffee - Google Patents

Abstract

The device comprises an infusion chamber defined by at least two parts (1, 3) movable in relation to each other to close and open the infusion chamber;a duct (7) to supply pressurized hot water to the infusion chamber;at least one pump (13) to supply pressurized hot water to the infusion chamber;a dispensing unit (16) to dispense coffee from the infusion chamber. The dispensing unit has at least a first configuration and a second configuration, according to the type of coffee to be dispensed;the two parts (1, 3) defining the infusion chamber have at least a first reciprocal position to define a larger infusion volume and a second reciprocal position to define a smaller infusion volume and are functionally connected to said dispensing unit, so that the dispensing unit is switched to one or other of said at least two configurations according to the reciprocal position taken by said parts defining the infusion chamber.

Description

APPARATUS TO PRODUCE COFFEE DESCRIPTION TECHNICAL FIELD The present invention relates to improvements to apparatuses or machines for producing coffee, both for domestic use and for professional and commercial use, for example in vending machines.

BACKGROUND OF THE ART The machines are currently available to produce espresso coffee, which comprises an infusion chamber into which is placed a load of ground coffee or a single-service sachet, in the form of a capsule, cartridge, capsule or similar, which contains coffee powder is placed and, through which pressurized water is subsequently flowed at a temperature high enough to extract the flavors of the coffee powder, whereby the drink is prepared. The characteristics of the drink that can be obtained with these machines can also vary based on the adjustments provided by the user, for example, these machines can produce espresso coffee at high pressure, forming the typical foam that distinguishes this drink or a more diluted coffee such as a filter or the so-called fresh percolated coffee, which is produced using lower pressures and larger amounts of water. The right solutions to select the coffee quality obtained currently used both in machines for private or domestic use and in machines for commercial or professional use or in vending machines in which the supply of coffee is subject to payment (using coins or prepaid cards) of the cost of the drink. EP-A-1,133,944 discloses a machine for producing coffee in which an infusion chamber is provided with a supplying apparatus designed to be capable of producing, at the user's choice, different amounts or types of coffee, for example more or less concentrated. More specifically, EP-A-1,133,944 discloses an apparatus for producing coffee which comprises a supply line for hot water supplied from a pump, a coffee supply apparatus, an infusion chamber in which the Hot water supply line flows and exits from which the coffee spout driver, which is part of the spout apparatus flows. The infusion chamber is delimited by reciprocally movable parts; one of which is in the form of a piston which slides with respect to a cylinder. To allow different qualities of coffee to be supplied a valve is placed on the dispensing apparatus and is provided with a stopper member associated with a preloading spring and the medium to allow modification of the cross section of the coffee outlet flow conduit to provide a first conduit with a smaller cross section operating at a higher pressure and with a lower flow rate, and a second conduit with a larger cross section operating at a higher flow rate and a lower pressure. In particular, one of the modalities described in EP-A-1133944 is provided with a valve for regulating the flow rate and a manually controllable reduction device or also by means of an actuator, established by the user of the machine, for Increase or decrease the cross section of the duct for coffee. By modifying the section of the duct, a greater or lesser pressure can be generated inside the infusion chamber and in this way the flow of coffee supplied and the water supplied to the infusion chamber are also modified, obtaining different qualities of coffee which can be select by the user. For similar functions and objectives, the subsequent publication EP-A-1,267,685 describes a machine for producing coffee in which the cross section of the The coffee duct is modified to change from a larger cross section to a smaller cross section or vice versa operating in operation of the pump supplying the pressurized water. More specifically, in EP-A-1,267,685 a coffee supply valve designed to automatically react to the water supply pressure is provided so that a larger supply pressure causes a reduction of the valve and therefore a slower flow out of coffee. By having the pump supply the water at a lower pressure and therefore, for example, by making the pump operate at a power below the rated power, the water supply pressure in the infusion chamber is below a value which causes the automatic reduction of the coffee outlet valve . The flow of water and therefore of the coffee supplied is greater than in the previous case and the production pressure is lower to obtain a more diluted coffee than the coffee obtained with the high pressure water supply. Therefore, the machine described in EP-A-1,367,685 requires control of the pump in order to operate. The operation of the pump at different pressures can generate a modification of the structure of the beverage supply valve and thus they can obtain coffees of different qualities.

OBJECTIVES AND BRIEF DESCRIPTION OF THE INVENTION The objective of the present invention is to produce an apparatus or machine for producing coffee which, in a simple and reliable way, allows coffee to be produced of different types or qualities. According to a particular embodiment, the objective of the present invention is to produce a machine which can produce high pressure coffee in a simple, reliable and easily controllable manner, typically espresso coffee and low pressure filter coffee, i.e. the so-called fresh percolated coffee. In substance, according to a first aspect, the invention relates to an apparatus or a machine for producing coffee comprising an infusion chamber defined by at least two parts movable one in relation to the other to close and open the infusion chamber; a conduit for supplying pressurized hot water to the infusion chamber; at least one pump for supplying pressurized hot water to the infusion chamber; a supply unit for supplying coffee from the infusion chamber to a delivery nozzle or the like. Characteristically, according to the invention: the supplying unit has at least a first configuration and a second configuration, in accordance with the type of coffee that is going to be supplied; the two parts defining the infusion chamber have at least a first reciprocal position for defining a larger infusion volume and a second reciprocal position for defining a smaller infusion volume; the two parts defining the infusion chamber are functionally connected to the supplying unit so that the supplying unit changes to one or the other of at least two configurations according to the reciprocal position taken by the parts defining the infusion chamber. In this way an apparatus is obtained which, with an extremely simple and reliable structure, can supply coffee with characteristics that vary greatly, for example from an espresso filled with foam to a diluted coffee known as American, percolated coffee or fresh filtered. The apparatus also allows the use of sacks or capsules of different dimensions in a single dispenser thanks to the possibility of obtaining closing positions in different positions of the infusion chamber with different switching in consequence of the dispensing unit. In principle, the change of the dispensing unit can be obtained, for example, with an electrical control operated directly by one or the other of the two reciprocally movable parts that form the infusion chamber.

For example, the electric control can act on a valve to partially limit the flow through the supply unit. This partial limitation may be obtained by completely closing one or more of a plurality of conduits or by reducing one or more conduits. For example, a movable part of the infusion chamber can act on one or more switches which control the change of the dispensing unit. However, in order to obtain a simpler and more reliable apparatus, of simpler construction and handling in a particularly advantageous embodiment of the invention at least one of the two defining parts of the infusion chamber is placed and designed to act mechanically on the dispensing unit to cause the change according to the reciprocal position taken by the two parts that define the infusion chamber. In this way, with a uniquely controlled actuator, the closing of the infusion chamber in one or other of two or more alternative closure positions can be controlled, defining different infusion volumes and in each of the positions the supply unit it is switched to the correct operating condition without the need for additional control, mechanisms or circuits and, if desired, without the need to act on the pump or hot water supply pumps. This returns to the device Extremely simple, resistant, reliable and cheap. For example, and typically, one of the parts defining the infusion chamber may be fixed and with respect to a load-bearing structure and the other may be moved, and designed and distributed to act mechanically on the dispensing unit and cause the change according to the position with respect to the fixed part. Advantageously, the supplying unit can be integral with the first of the two parts defining the infusion chamber, that is, with the fixed part with respect to the structure of the machine or apparatus. In a preferred embodiment of the invention, the supplying unit has a first conduit with a larger cross-section for supplying coffee at a lower first pressure (fresh percolation) and a second conduit with a smaller cross-section for supplying coffee at a further second pressure high (express) In addition, a closure member can advantageously be associated with the first conduit, positioned and controlled so that it is changed to a closed position of the first conduit when the two parts defining the infusion chamber are placed in the second reciprocal position. In this way, only the second conduit with a smaller cross-section suitable for causing coffee infusion at high pressure, for example to produce coffee, remains open. express. In an apparatus configured in this way the closure member, to close the first conduit, is mechanically controlled directly by one of the parts defining the infusion chamber. When the supplying unit is fixed with respect to the first of at least two parts mentioned before defining the infusion chamber, the second of the two parts, which can be moved with respect to the first, may have an edge that acts on the supply unit, for example directly on the closure member. This makes it possible to avoid any type of mechanical transmission or connection and at the same time does not exclude the possibility of the change being made mechanically according to the reciprocal position of the two parts defining the infusion chamber but interposed, for example, by a transmission member of a control movement instead of doing it directly. This can be carried out, for example, when the supplying unit is not built in one piece with the fixed part of the infusion chamber or is not placed in close proximity with the movable part, which controls the change thereof . The second conduit of the supplying unit can advantageously be provided with a back pressure valve. The back pressure valve is designed as a member which allows a pressure greater than the pressure which would be obtained if the valve was not present, which is maintained at the entrance of the duct or inside the infusion chamber. In this way, the pressure at which the flavors of the coffee powders are extracted can be increased even considerably. Typically, this pressure can be between 5 and 15 bar, however, values in which they can be considered as indicative and not limiting. At higher pressures, closer to the upper limit, stronger beverages are obtained with the typical foam characteristic of espresso coffee. To provide the apparatus with greater flexibility of use, according to a possible mode, the back pressure valve can be adjusted to increase or decrease the extraction pressure. This forms an additional variable parameter when establishing the infusion conditions and therefore the quality of the beverage that is obtained. Additionally or alternatively to the simple back-pressure valve, a valve for regulating the flow rate can be associated with the second conduit of the supply unit, as will be described with reference to a specific embodiment of the invention. In turn, this valve can be regulated by the user to obtain an additional degree of freedom when establishing the conditions of infusion. The regulation can be carried out directly, for example by actuating a screw apparatus or, and preferably, by means of an electromechanical or hydraulic actuator which responds to an instruction transmitted by a control unit. In fact, the apparatus can be conveniently provided with a control unit which administers the various regulations and adjustments so that the type and characteristics of the beverage can be established by the user by means of a simple and impulsive interconnection, a programmable unit to establish the regulation of the various parts of the machine. Preferably and advantageously, the pump or pumps of the apparatus are vibration pumps with an actuator comprising an electromagnet, a piston and a power supply that is obtained by cutting through a diode of an alternating current in the form of sinusoidal wave. It is also possible to use other types of pumps. There can also be two or more pumps, identical or different from each other, for example regarding power, supply pressure, flow rate, etc. These pumps can be activated alternatively or in various combinations with each other, according to the conditions of supply and infusion.

However, in a preferred embodiment a pump (or a group of pumps) always controlled to supply the maximum pressure compatible with the characteristics of the hydraulic circuit connected to the supply side of the pump and any of the closed or open conditions of the first is provided. or second conduits of the supplying apparatus. In this case, therefore, the pump is designed and controlled to always operate on the same characteristic curve, regardless of the changing conditions of the supply unit. If the pump is controlled to operate in different operating conditions according to the desired characteristics of the coffee, it can be obstructed by supplying power intermittently or with an obstruction voltage. The blocking or controlled modification of the pump supply conditions is particularly advantageous when the supplying unit changes to supply the so-called fresh filtered or percolated coffee. Additional features and advantageous embodiments of the apparatus according to the invention are indicated in the appended claims and will be described with reference to some mode examples.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by the following description and appended drawings, which show non-limiting practical embodiments of the invention. More specifically, in the drawings: Figures 1 to 5 show a schematic longitudinal section of an apparatus according to the invention in a first embodiment and in various phases of operation; Figure 6 shows a diagram of the pressure-flow characteristic curve of the pump, for example a vibration pump usable in the apparatus according to the invention; Figure 7 shows a plan view of the infusion unit for an apparatus according to the invention in an improved embodiment of the apparatus; Figures 8 and 9 show sections according to lines VIII-VIII and IX-IX in Figure 7 in a first condition of operation for supplying espresso coffee; Figure 10 shows an enlarged detail in a section according to the line X-X in Figure 7 of the apparatus in the configuration of Figures 8 and 9; Figures 11 and 12 are figures equivalent to Figures 9 and 10 of the apparatus in a configuration for delivering fresh filtered or percolated coffee; Figure 13 shows an enlarged section of the supply conduit or passage with a larger section in a modified embodiment in a section analogous to that of Figure 10; Figure 14 shows a section of the detail of the duct with a smaller section in a modified embodiment and with a manual region of coffee quality; Figure 15 shows a perspective view of a coffee machine coupled with the infusion unit similar to one of Figures 7 to 12; and Figures 16 and 17 show a diagram of the waveform of the supply voltage of the pump in a configuration with a pump to which it can be subjected to obstruction.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES OF THE INVENTION Figures 1 to 5 show in principle on which the invention is based, with reference to a schematic configuration. The figures show exclusively the elements of a machine or apparatus for producing coffee which are required in order to understand the present invention while the elements which are part of the machine but are known per se and are not necessary for understand the machine They have been omitted. More specifically, the figures show the infusion chamber with the components of which it is constituted and, in a schematic manner, the opening and closing mechanisms of the infusion chamber and the supply of pressurized water. Two parts or portions that can be moved relative to each other, indicated generally with the numbers 1 and 3, define an infusion chamber into which the coffee powder is placed to produce the beverage. In the following, reference will be made to a system for preparing the beverage by means of coffee powder loaded directly into the infusion chamber and comprised therein to form a charge or a tablet of coffee powder. However, it is also possible to use single serve bags or coffee powder such as capsules or pierceable cartridges, capsules or the like which are inserted individually into the infusion chamber. In this case the chamber can be provided, if necessary, with suitable perforators to perforate the walls of the cartridge or capsule and allow the entry of pressurized water and the extraction of the beverage from the single service bag. In the schematic example shown, the lower portion of part 3 can be moved and acquires the structure of a cylinder with a cavity 3A which defines the internal volume of the infusion chamber, whose base is indicated by 3B, placed adjacent to which is an ejector 5 that is provided with a filter. As explained in the following, the purpose of the ejector 5 is to expel the spent coffee powder after the beverage has been supplied. An orifice 7 is provided to supply pressurized hot water that comes from a line 9 of water to the infusion chamber. The water is extracted from a reservoir indicated schematically with the number 11 by means of a pump 13, placed downstream of which is a heating element, for example an electrically activated instantaneous booster, indicated schematically with the number 15, which it heats the pressurized water by the pump 13 to the desired temperature. The part of the portion 1 is fixed and a coffee dispensing apparatus or unit is produced in one piece by which, in this example, it includes a first passage or conduit 17 with a larger cross section, with an inlet 17A facing the volume 3A internal to the infusion chamber and an outlet 17B which is connected to the one beverage supply line, indicated schematically with the number 19 and ending in a manner known per se with a spout 19A from the which coffee is supplied to be collected at a rate T or another container placed specifically below the spout 19A. The dispensing unit, indicated with the number 16, also includes a second passage 21 with a cross section substantially smaller than the passage 17 and having an inlet 21A, also facing the internal volume 3A of the infusion chamber and which is provided , at the opposite end to the inlet 21A with a reducing or reducing valve 23. Downstream of the reducing valve 23 the outlet of the second passage 21 is connected to the coffee supplying line 19 by means of a line 25. Associated with the first passage or conduit 17 with a larger cross section is a closure member 27, schematically represented by a slide which moves transversely with respect to the axis of the conduit or passage 17 and which is provided with a drive disc 27A which cooperates , as will be explained in the following with an annular edge 3C of the movable part 3 which forms - together with the fixed part 1 - the infusion chamber. The movable part 3 is provided with a movement according to the arrow f3 imparted by a kinematic mechanism represented schematically by a connecting rod-crankshaft system constituted by an eccentric 28 and a connecting rod 29. A kinematic mechanism, not shown, operates the ejector 5. In practice, the movements of both the ejector 5 and the part 3 of the infusion chamber can be imparted with a kinematic mechanism known per se and used, for example, in machines produced by Saeco International Group SpA known by the trade names Idea, SG500, FS400, Royal, SG200, Magic, Incanto, Vienna and others. This kinematic mechanism is also described in EP-A-0 154 206 which can be referred to for further details. Figure 1 also schematically indicates a motor 31 which controls the rotation of the eccentric 28. The control unit, indicated schematically with the number 33 is, for example, a microprocessor suitably interconnected with the user by means of an interconnection indicated schematically with the number 35 and connected to an engine 31 to control the movements of the eccentric 28. The operating cycle of the apparatus described in the foregoing with reference to Figure 1 is schematically represented in the sequence in Figures 2, 3 and 5 or 2, 4, and 5, in two different modes of use. In figure 2, the movable part 3 is in the lower position thereof which corresponds to the dead center bottom of the eccentric 28 and connecting the kinematic mechanism of the rod 29. In this position, by means of a loading apparatus 36, indicated schematically in figure 2 and known per se, the coffee powder is loaded inside the compartment 3A inside the movable part 3. Figure 3 shows the closing position of the infusion chamber, position which is reached by taking the movable part 3 with the edge 3C thereof at a higher height with respect to the lower side of the fixed part 1. Figure 3 represents one of at least two possible alternative operating positions that can be taken by the apparatus. In this position, the edge 3C of the movable part 3 is in proximity or in contact with the lower disk 27A of the closing member 27, but without the latter reaching the closed position. The internal volume of the infusion chamber defined by coupling of parts 1 and 3 is relatively large and the coffee powder contained within this chamber has been comparatively little compressed. The degree of compression of the coffee powder depends on the amount of coffee placed in the volume 3A and in the final position acquired by the movable part 3. At this point, the pump 13 is operated to supply the coffee. This can be designed and controlled advantageously to always operate in a unique characteristic curve corresponding to the maximum power.

Insofar as the closing member 27 has not closed the passage 17 with the largest cross section and as the coffee powder of the infusion chamber compresses only moderately, the loss of upper part along the path of the water and the beverage produced by the apparatus is reduced and consequently the pump 13 supplies a high flow rate of water at low pressure, for example typically 3 bar, the value is considered indicative and not limiting. At this pressure, reducer 23 can be completely closed so that the coffee flowing from the infusion chamber passes exclusively through the first passage or conduit 17 with larger cross-section. It is also possible for the reducer 23 to open slightly, in which case part of the supplied coffee will pass through the passage 21 and line 25 and will be reunified on line 19 with the main flow of coffee supplied through passage 17. The coffee produced in this way will have the characteristic of percolated coffee or fresh filtered. However, the same apparatus can be changed to an operating condition to produce espresso coffee or in any case a stronger and denser coffee, by operating at a higher pressure and with a lower flow rate of water supplied from the pump 13. In In this case, the parts of the apparatus described in the above will have the configuration shown in figure 4, in which the coffee powder is inserted into the infusion chamber and is compressed to a greater degree, followed by an increased upward displacement of the movable part 3 and consequent reduction of the volume 3A of the infusion chamber. The compaction of the coffee powder may be greater, with respect to the configuration in Figure 3, also due to possibly a greater amount of powder placed in the volume 3A of the infusion chamber. The increased upward displacement of the movable portion of the part 3 also causes consequent closure, through the closing member 27 of the passage 17 with larger section. As a consequence of this, along the path of the liquid from the pump to the supplying spout 19A there will be a pressure drop substantially greater than that which is obtained in the configuration in Figure 3. This is because the powder coffee in the infusion chamber has been compressed to a greater degree and above all because the passage 17 has been closed and consequently the coffee produced in the infusion chamber must pass through the narrower passage or conduit 21. This passage is closed by the reducer 23 which causes an increase in the pressure at the outlet of the pump until sufficient pressure is reached in the duct 21 for opening the reducer or reducing valve 23. This pressure can be established at the factory or during installation, by acting on an elastic member 23A acting on a closing element 23B (for example a needle or sphere). It is also possible to limit the pressure at which the reducer 23 opens to be adjustable by the user, for example by means of an adjusting member which modifies the degree of preload of the spring or other elastic element 23A. In any case, the pump 13 in this case will supply (with the passage 17 closed) a lower flow rate at a higher pressure than in the configuration of figure 3. If the pump is designed and controlled to operate always at maximum power, in the practice will have an operation point in the same characteristic curve as the operation point in the configuration of figure 3. Although in the case of figure 3 the water supplied from the pump may have a pressure of approximately 3 bar, in the case from Figure 4 the coffee supply pressure from the infusion chamber can be regulated, for example, at 7 bar or even higher values, for example typically up to 15 bar, by means of suitable calibration of the reducer 23 and the spring 23A compression of the same. However, these pressure values can be considered indicative and not limiting and they can vary, for example, according to the machine type (for example for domestic use, for professional use, a vending machine or similar). The diagram in figure 6 shows in an extremely schematic manner a curve C characteristic of the pump 13, the pressure values are indicated in the ordinates and the flow values in volume of water are indicated in the abscissa. Two points, A and B are indicated in characteristic curve C, which correspond to the operation of the pump in the case of an open passage 17 (figure 3) and in the case of a closed passage 17 (figure 4). Flows under both conditions are indicated as HA and HB while the respective pressures are indicated as PA and PB. It is understood that the two operating points A and B of the pump are the direct consequence of the different pressure drop along the path of the liquid within the apparatus resulting from the closing of the passage 17 and, to a lesser degree of one degree Different compression of the coffee powder in the infusion chamber. Therefore, simply by controlling the movement of the movable part 3 of the infusion chamber and reaching one or the other of the two positions shown in Figures 3 and 4, substantially different coffee qualities can be obtained with the same delivery unit. no need for any operation to regulate the pump. Consequently, it can be designed to operate optimally (for example with maximum efficiency) in a single characteristic curve which will be used (curve C in Figure 6) in all operating conditions of the unit. However, it is also possible to add a pump control to the described configuration to modify the operating conditions of the pump. Figure 5 shows the step subsequent to one for supplying the coffee, in which the movable part 3 is returned down while the ejector 5 is operated to eject the used coffee powder from the infused powder and place the supplying unit for a cycle of new operation. Figures 7 to 12 show the practical application of the invention to a supplying unit of the type currently used in numerous coffee machines produced by Saeco International Group s.p.a. and described, for example, in EP-A-0,154,206. The parts equivalent to those illustrated in the schematic embodiment example of the previous figures are indicated by the same reference numerals. These figures show that parts 1 and 3 (fixed and movable, respectively) that define the infusion chamber, the internal volume of which is indicated by the number 3A.

The disc for extraction or expulsion of the coffee powder used is indicated with the number 5, which is controlled by a lever mechanism formed by a lever 6 that oscillates around a fixed axis and articulated in 10 to a rod 8 rigidly limited to the disc 5. A crankshaft indicating with the number 28, functionally equivalent to the eccentric 28 and connected to the connecting rod 29 to control the movement of the movable part 3 with respect to the fixed part 1. A fixed support structure is indicated by the number 30, which advantageously forms a single and separable body of the machine, which is shown by way of example in Figure 15. The configuration of the part 1 fixed with the passages or conduits 17 and 21 produced herein is shown, in particular, in the section of Figures 10 and 13. In this embodiment example, the single reducer 23 is replaced with a valve 31 for regulating the flow rate of the type indicated in detail in the EP document. -A-1,133,944 and its equivalent US-A-6, 682, 083, the contents of which form an integral part of the present description and to which reference can be made for additional details. The structure and operation of the valve 31 is briefly described in what follows. A valve body 33, in which a perforation 35 is produced, is inserted into the conduit or passage 21. Extending into the perforation 35 is a needle-shaped plug 37 with a surface 37A cooperating with the edge of the bore 35 calibrated to close it. The plug 37 has a rod 37B which extends coaxially through a cover 39 coupled with a bayonet coupling or in some other suitable manner in a housing produced in the valve body 33. The rod 37B of the plug 37 has a disc 41 against which a compression helical spring 43 acts which is held compressed between the disc 41 and the interior of the lid 39. In this way, the plug 37 is maintained with the surface 37A of closure thereof away from the edge of the perforation 35. Maintained between the disk 41 and an annular support surface 33A of the valve body 33 is a disc-shaped membrane 45, the perimeter edge 45A of which is clamped between the body of the valve 33 and the cover 39. The compression force of the spring 43 holds the membrane against the annular surface 33A. Defined between the perforation 35 and the surface of the membrane 45 facing the perforation is a volume 47 which can be produced to communicate with an outlet conduit 21X which substantially forms a continuation of the conduit 21, when the membrane 45 rises from the support surface 33A against the force of the compression spring 43. The conduit 21X is connected to a line 25 of coffee outlet. The valve 31 briefly described in the above behaves as a flow regulating valve. In fact, when the coffee flow in the passage 21 is high and tends to exceed a set value, defined by calibration of the spring 43, the membrane 45 (which is partially relieved from the housing 33A when there is an adequate coffee pressure supplied. along the conduit or passage 21) is further deformed against the force of the spring 43 causing reduction and finally closing of the perforation 35 by the needle plug 37. This reduces or completely interrupts the flow of coffee through the duct 21 in the volume 47 and therefore, as coffee is present in the latter, is supplied through the duct 21X, the membrane returns to the supporting surface 33A by the action of the compression spring 43. Consequently, the perforation 35 tends to open again. This results in effective flow regulation. By adjusting the spring recharge 43 this adjusts the flow rate, all as described in US-A-6, 382, 083 mentioned above. In the embodiment in Figures 7 to 12, the closure member 27 is designed as a slidable rod in a housing 51 produced in the fixed part 1 of the apparatus with an annular seal 53. The end of the rod (which forms the closure member 27) indicated with the number 27A cooperates with the movable part 3 of the infusion chamber while the opposite end, indicated with the number 27B has a seal 55 which can act as a seal (when the closure member 27 is in the closed position) on the housing 17C. A disc 27C is integral with the rod and forms the rod guide and stop against which the coil spring 54 reacts to tension the rod in the open configuration. The operation of the apparatus of figures 7 a 12 is the following. When the infusion chamber is closed in the configuration, in figures 8, 9 and 10, the volume 3A of the infusion chamber has a minimum dimension. The upper edge 3C of the movable part 3 pushes the rod forming the closing member 27 into the closed position, where the seal 55 presses against the annular housing 17C. In this way the duct or passage 17 closes perfectly. Once operated, the pump delivers pressurized water into volume 3A through the tablet of compressed coffee powder. The beverage, obtained by extracting the flavors and substances from the coffee powder by means of pressurized and heated water, through the passageway or conduit 21 and through the valve 31, reaches the conduit 21X and then the conduit 25 (which is connects to duct 17 downstream, towards a spigot, not shown and identical to spigot 19). Valve 31, properly calibrated, regulates the flow of water and therefore coffee. The time in which the hot water remains in contact with the coffee powder in this way is set to a desired value according to the strength of the coffee obtained from the machine. In this configuration, the appliance supplies espresso coffee. Although the example does not show members that can be used by the user to modify the flow rate, these can undoubtedly be produced, for example, as described in US-A-6, 382, 083. When the apparatus is used to supply fresh filtered or percolated coffee, has the configuration in figures 11 and 12. The closing member 27 is in the open condition and the volume 3A inside the infusion chamber is larger with respect to the configuration in figures 8 to 10. The coffee obtained by infusion in the volume 3A is supplied mainly through the conduit or passage 17 where it finds less obstruction. There is no flow or there is an imperceptible flow, which in any case is recovered through line or conduit 25, which passes through conduit 21. Figure 13 shows a variant of the modality of closure member 27, in which board 27B is replaced by a membrane 56. A spring, indicated with the number 100, stresses the member 27 in the open position. In this case, the spring is external with respect to the conduit for the passage of the coffee. Figure 14 shows a variant mode of the valve 31 for regulating the flow rate. With respect to the previously described embodiment, in this case, downstream of the membrane 45 a needle or reducing valve 61 is provided along the conduit 21X with a knob 63 which can be used to regulate the position of the reducer 61 with respect to a housing 65. This produces a reducing valve for regulating the back pressure and consequently the infusion pressure. This regulation can be carried out in the factory, during the installation or during the use by the user. In the latter case, an actuator controlled by a control unit interconnects the user through a control keyboard or the like and can advantageously be provided to act on the rod 61. As mentioned in the above, the pump or puwhich supply pressurized hot water to the infusion chamber can be controlled so that they always operate at maximum power. In this case, depending on the mode in which the supplying unit is placed (comprising the passages 17, 21, the closing member 27, the reducing valve 23 or flow control valve 31), the pump will operate at one or another operating point along the characteristic curve thereof. However, it is also possible to adjust the operating speed of the pump or pu for example through the same control unit that manages the remaining parts of the machine such as the movement of part 3 of the infusion chamber. If the pump used is a membrane pump, that is, a vibration pump controlled by an electromagnet, which can clog, by making it operate intermittently. This can be obtained by cyclically interrupting the power supply to the electromagnetic actuator of the pump. Alternatively, the duty cycle of the pump can be reduced to obtain interruption by acting on the waveform of the supply voltage. Figure 16 shows the waveform of the supply voltage V. This is obtained by canceling the negative half cycle of the network voltage using a diode. When the pump operates at full speed, the entire waveform of the voltage is used. On the other hand, when, for example, the flow rate of the pump is to be reduced, the supply voltage is varied as shown in the diagram in Fig. 17. In each positive half-cycle the power supply is interrupted when the voltage reaches (in the instant ti) the value VI. This regulation can be particularly useful when the apparatus operates with the switched supply unit as in figures 11 and 12 to produce fresh percolate coffee. In this case, the obstruction of the pump reduces the flow rate, which makes it possible to produce a more loaded coffee. Regardless of the configuration of the described apparatus, it can be produced as a detachable block of the coffee machine without the use of particular tools to facilitate in this way any maintenance, repair, cleaning or similar operation. It is understood that the drawings simply show a non-limiting practical embodiment of the invention which may vary in form and distribution without thereby reaching the scope of the invention as defined in the appended claims.

Claims (27)

1. CLAIMS 1. Apparatus for producing coffee, comprising an infusion chamber defined by at least two movable parts one in relation to the other to close and open the infusion chamber; a conduit for supplying pressurized hot water to the infusion chamber; at least one pump for supplying pressurized hot water to the infusion chamber; a supplying unit for supplying coffee from the infusion chamber; wherein the supplying unit has at least a first configuration and a second configuration, according to the type of coffee to be supplied; the two parts defining the infusion chamber have at least a first reciprocal position for defining a larger infusion volume and a second reciprocal position for defining a smaller infusion volume; the two parts defining the infusion chamber are functionally connected to the supplying unit so that the supplying unit changes to one or the other of at least two configurations according to the reciprocal position acquired by the parts defining the infusion chamber; characterized in that the supplying unit includes a first passage with a larger cross section to supply coffee at a first pressure and a second passage with a smaller cross section to supply coffee at a second pressure, the second pressure is greater than the first pressure; a closure member is associated with the first passage; and the closure member is distributed and controlled to change to the closing position of the first passage when the two parts defining the infusion chamber change to the second reciprocal position. Apparatus as described in claim 1, wherein the closure member is directly controlled by one of the parts defining the infusion chamber. Apparatus as described in claim 1 or 2, wherein at least one of the two parts defining the infusion chamber is distributed and designed to act mechanically on the supply unit to cause the change according to the reciprocal position of the two parts that define the infusion chamber. Apparatus as described in claim 1, 2 or 3, wherein one of the defining parts of the infusion chamber is fixed with respect to a support structure and the other of the two parts is movable, the movable part it is designed and distributed to act mechanically on the supplying unit and cause the change according to the precision with respect to the fixed part. 5. Apparatus as described in one or more of the previous claims, wherein the supplying unit is integral with the first of the two parts defining the infusion chamber. Apparatus as described in claim 5, wherein the supplying unit is integral with a first fixed part, the second part defines the infusion chamber which is movable. Apparatus as described in one or more of the preceding claims, wherein the supplying unit is integral with the first of the two parts defining the infusion chamber and the second of the two parts has an edge that acts on the member closing. Apparatus as described in one or more of the preceding claims, wherein the back pressure valve is associated with the second passage. 9. Apparatus as described in claim 8, wherein the back-pressure valve is adjustable with manual or electrical adjustment. Apparatus as described in one or more of the preceding claims, wherein the flow regulating valve is associated with at least the second passage of the supply unit. 11. Apparatus as described in claim 10, wherein the members to adjust the flow through the second passage are associated with the flow regulation valve. Apparatus as described in claim 11, wherein the adjustment is made by regulating the preload of a spring associated with a plug of the second passage or by regulating the useful cross section of flow of the second passage. Apparatus as described in one or more of the preceding claims wherein the closure member includes a rod elastically tensioned in an open position, with one end cooperating with one of at least two parts defining the infusion chamber. Apparatus as described in claim 13, wherein the rod comprises a second end for closing the first passage. 15. Apparatus as described in claim 13 or 14, wherein the rod cooperates with an elastic sealing member to close the first passage. Apparatus as described in one or more of the preceding claims, wherein at least one pump is a vibration pump. Apparatus as described in one or more of the preceding claims, wherein at least one pump is controlled to always supply maximum pressure in any open or closed condition of the first or second passage of the supplying device. 18. Apparatus as described in one or more of the preceding claims wherein at least one pump is designed and controlled to always operate on the same characteristic curve, regardless of the conditions at which the supplying unit changes. 19. Apparatus as described in one or more of the preceding claims wherein at least one pump is controlled to operate in different operating conditions in accordance with the desired coffee characteristics. 20. Apparatus as described in claim 19, comprising means for clogging the pump according to the characteristics of the desired coffee. Apparatus as described in claim 19 or 20, wherein at least one pump is controlled with a variable duty cycle. 22. Apparatus as described in one or more of claims 19 to 21, wherein at least one pump is controlled so that when the supplying unit changes to produce a smaller portion of coffee, at least one pump is regulated to provide a higher or lower flow or pressure according to the characteristics of the desired coffee. 23. Apparatus as described in one or more of the previous claims comprising at least two pumps. 24. Apparatus as described in claim 23, wherein the pumps have different characteristics from each other. 25. Apparatus as described in claim 23 or 24, wherein the two pumps are controlled to be activated alternatively or in combination according to the condition in which the supplying unit changes. 26. Apparatus as described in one or more of the preceding claims wherein the infusion chamber has a configuration for receiving bags of a single service of different dimensions, the size of the bag of a single service determines the closing position of the two parts that define the infusion chamber. 27. Apparatus as described in one or more of the preceding claims, characterized in that it can be separated without the use of tools.