PROCESS FOR IMPROVING THE UNIFORMITY OF CONCENTRATION OF ESPRESSO COFFEE IN AN ESPRESSO COFFEE MACHINE AND ASSOCIATED ESPRESSO COFFEE MACHINE

Abstract

A machine for the preparation and dispensing of espresso coffee is described, said machine comprising: a coffee boiler, a filter holder with a filter for a pressed coffee powder puck, a pre-infusion chamber and a hydraulic circuit for transporting pressurized water from said coffee boiler to the pre-infusion chamber, wherein said machine further comprises a device for detecting a parameter indicative of the filling of said pre-infusion chamber and of said hydraulic circuit so that the step of dispensing of an espresso coffee can be started on the basis of said defected filling parameter.

Claims

1. A machine for the preparation and dispensing of espresso coffee comprising: a coffee boiler, a filter holder with a filter for a pressed coffee powder puck, a pre-infusion chamber and a hydraulic circuit for transporting pressurized water from said coffee boiler to the pre-infusion chamber, wherein said machine further comprises a device for detecting a variation in the value of a parameter indicative of the filling of said pre-infusion chamber and of said hydraulic circuit so that the step of dispensing an espresso coffee can be started on the basis of said detected variation in the value of said filling parameter.

2. The machine as claimed in claim 1, wherein said device for detecting a variation in the value of a parameter indicative of the filling of said pre-infusion chamber and of said hydraulic circuit comprises a flowmeter.

3. The machine as claimed in claim 1, wherein said flowmeter is configured to detect a slowing of the water flow, wherein said slowing of the water flow is indicative of the filling of said pre-infusion chamber and of said hydraulic circuit.

4. The machine as claimed in claim 1, wherein said device for detecting a variation in the value of a parameter indicative of the filling of said pre-infusion chamber and of said hydraulic circuit comprises a pressure transducer.

5. The machine as claimed in claim 4, wherein said pressure transducer is configured to detect a pressure difference of the water, wherein said pressure difference of the water is indicative of the filling of said pre-infusion chamber and of said hydraulic circuit.

6. The machine as claimed in claim 1, wherein said device for detecting a variation in the value of a parameter indicative of the filling of said pre-infusion chamber and of said hydraulic circuit comprises a weighing device.

7. The machine as claimed in claim 6, wherein said weighing device is configured to detect a weight or mass variation of a container for collecting the dispensed espresso coffee, wherein said weight or mass variation is indicative of the filling of said pre-infusion chamber and of said hydraulic circuit.

8. A process for preparing an espresso coffee with an espresso coffee machine, the machine comprising a coffee boiler, a filter holder with a filter for a pressed coffee powder puck, a pre-infusion chamber and a hydraulic circuit for transporting pressurized water from said coffee boiler to the pre-infusion chamber, the process comprising detecting a variation in the value of a parameter indicative of the filling of said pre-infusion chamber and of said hydraulic circuit and dispensing espresso coffee on the basis of said detected variation in the value of said detected filling parameter.

9. The process as claimed in claim 8, wherein said variation in value of the filling parameter comprises a variation of at least one of the following: a parameter indicative of the water flow, a parameter indicative of a water pressure and a parameter indicative of a weight or mass of the espresso coffee dispensed in a container.

10. The process as claimed in claim 9, wherein said variation in value of the filling parameter comprises a slowing of the water flow or a pressure difference or a mass or weight variation.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0023] There now follows a detailed description of the present invention, provided by way of a non-limiting example, to be read with reference to the accompanying figures, in which:

[0024] FIG. 1 is an axonometric view of an example of an espresso coffee machine in which the present invention may be incorporated;

[0025] FIG. 2 is a first embodiment of a hydraulic circuit diagram of an espresso coffee machine according to the present invention;

[0026] FIG. 3 is a second embodiment of a hydraulic circuit diagram of an espresso coffee machine according to the present invention;

[0027] FIG. 4 is a cross-section through the coffee boiler and a filter holder without water;

[0028] FIG. 5 shows the same components as in FIG. 4 with a first amount of water in the circuit leading to the coffee powder puck; and

[0029] FIG. 6 shows the same components as in FIG. 4 with the water which fills completely the circuit and all the space above the coffee puck;

[0030] FIGS. 7-9 are three different flow diagrams of three variants of the method according to the present invention; and

[0031] FIG. 10 show the connection between a detection device and a processing device.

DETAILED DESCRIPTION

[0032] FIG. 1 shows, purely by way of example, an espresso coffee machine denoted overall by the reference number 1000. The machine 1000 comprises a substantially closed machine body 1001 which houses the main components of the machine, some of which will be described below. At the top, preferably, the machine 1000 comprises a surface 1002 on which the cups can be placed. An electrical resistance (not shown) or other heating system for heating the cups on the surface 1002 may also be provided.

[0033] The machine 1000 comprises at least one dispensing group 1003 for dispensing espresso coffee. Preferably, the machine 1000 comprises several dispensing groups 1003, for example three groups, like the machine shown by way of example in FIG. 1. There could also be two, four or more dispensing groups. A drip tray 1004, which is preferably partially closed at the top by a grid 1005, is preferably present underneath the dispensing groups 1003. Typically the coffee cups are placed on the grid 1005 during dispensing of the espresso coffee.

[0034] A filter holder for supporting a filter for a coffee powder puck may be removably connected to each dispensing group 1003.

[0035] The machine 1000 may comprise one or more displays 1010 and pushbuttons, for example for switching on/off the machine and/or for starting/ending dispensing.

[0036] The machine 1000 shown in FIG. 1 also comprises, for each dispensing group 1003, a lever 1112 for starting/ending dispensing of the espresso coffee and/or for modifying the dispensing pressure during dispensing of the espresso coffee.

[0037] Before describing in detail the hydraulic diagram shown in FIGS. 2 and 3, the various reference numbers used, together with a short description of the single components, are indicated below.

[0038] 1 COFFEE BOILER

[0039] 10 PUMP

[0040] 11 EXPANSION VALVE

[0041] 12 CHECK VALVE

[0042] 13 PRE-HEATER MIXING VALVE

[0043] 14 STEAM BOILER

[0044] 15 DECOMPRESSION VALVE

[0045] 16 FLOWMETER (VOLUMETRIC METER)

[0046] 18 BALL TAP

[0047] 19 STEAM ELECTROVALVE

[0048] 20 STEAM WAND

[0049] 21 HOT WATER MIXING VALVE

[0050] 22 STEAM BOILER FILLING ELECTROVALVE

[0051] 23 HOT WATER WAND

[0052] 24 PRESSURE TRANSDUCER

[0053] 25 STEAM BOILER PRESSURE GAUGE

[0054] 26 DRAINAGE WELL

[0055] 27 GEAR PUMP

[0056] 28 SAFETY VALVE

[0057] 29 WEIGHING SYSTEM

[0058] In FIGS. 2 and 3 the following symbol system has been used: the cold water flow is indicated graphically by a long dash-single short dash-long dash line; the hot water flow is indicated graphically by a continuous line, the steam flow is indicated graphically by a broken line and, finally, the discharge water flow is indicated graphically by a long dash-short double dash-long dash line.

[0059] Briefly, in the exemplary diagram shown in FIG. 2, the cold water from the mains (or from any other source) is supplied to the pump 10. The pump 10 supplies the water to the steam boiler 14, preferably passing through the non-return valve 12 and the preheater mixing valve 13.

[0060] Preferably, the steam wand 20 is connected to the steam boiler 14 so as to dispense steam and, for example, foam the milk for making a cappuccino.

[0061] Preferably, the steam boiler 14 is in fluid communication with the hot water wand 23 in order to supply hot water for preparing infusions (tea or tisanes, for example).

[0062] As shown in FIG. 4, the water from the coffee boiler 1 is conveyed to the dispensing group 1003 by means of an infusion electrovalve 9 and an infusion water pipe 6. In particular, the water from the pipe 6 preferably reaches a shower screen 4 by means of which it is distributed substantially uniformly over a coffee powder puck contained inside a filter 7 supported by the filter holder 8. The coffee powder puck comprises ground coffee which has been pressed by the barman before the filter holder is engaged with the bottom part of the dispensing group 1003.

[0063] Preferably, the infusion electrovalve 9 is a three-way valve. The infusion electrovalve 9 comprises a first path for drawing infusion water from the coffee boiler 1, a second path connected to the infusion water supply pipe 6 and a third path for connecting the infusion zone to the discharge outlet.

[0064] The infusion water supply pipe 6 is preferably in fluid communication with a diffuser screw 3 and with the shower screen 4.

[0065] During use, when a user wishes to prepare an espresso coffee, he/she presses a button (or starts the extraction process in some other way). The infusion water is drawn via the take-off pipe of the infusion electrovalve 9 of the coffee boiler 1 and is directed towards the coffee puck via the infusion water supply pipe 6. The pressurized water starts to flow into the infusion water supply pipe 6 (FIG. 5) until it is completely filled. Then, the pressurized hot water flows into the empty space above the coffee puck.

[0066] The expression empty space above the coffee powder puck (or similar expressions) is understood as meaning in the present description and in the claims a space (or volume) which, before preparation of an espresso coffee starts, is not filled with water. This space or volume is bounded at the bottom by the coffee powder puck and at the top by the coffee boiler. Typically this empty space comprises a pre-infusion chamber, an infusion electrovalve and a pipe for supplying infusion water. The term pre-infusion chamber is understood as meaning a chamber bounded at the bottom by the upper surface of the coffee puck, laterally by the upper portion of the side wall of the filter which contains the coffee puck and, at the top, by the bottom surface of the dispensing group. Below, this empty space will be indicated by the letter V.

[0067] The espresso coffee machine according to the present invention is able to estimate, directly or indirectly, the volume of this empty space above the coffee puck and not intended for the infusion.

[0068] The main aim of the machine according to the present invention is that of ensuring repeatability and uniformity of the amount of water which passes through the coffee puck during preparation of the infusion. In order to be able to achieve this result it is necessary to define the amount of water which will be used to fill the empty space upstream of the coffee puck before starting the extraction step. The machine according to the present invention is configured to determine, for each coffee infusion, the amount of water which passes through the puck, assessing how much of the total water dispensed is used to fill the empty spaces.

[0069] According to a first embodiment, the machine comprises a volumetric meter (flowmeter) 16 connected to a control unit (CPU) 60 of the machine 1000 (FIG. 10a). Preferably, the flowmeter 16 is arranged immediately downstream of the infusion electrovalve 9. Alternatively, the flowmeter 16 could be arranged in another position, further downstream or upstream of the infusion electrovalve 9. The connection between the flowmeter 16 and the control and/or processing unit 60 may be performed by cable or wirelessly.

[0070] According to the present invention, a slowing of the flow detected by the flowmeter 16 is indicative of filling of the empty space V above the coffee puck. In other words, when a user starts dispensing a dose of espresso coffee, the pressurized water starts to flow freely inside the infusion water supply pipe 6 until the empty space V above the coffee puck is filled. Once this entire volume V has been filled, the pressurized water flow slows down because it encounters the resistance of the coffee puck. This resistance is detected by the flowmeter 16, typically owing to the fact that the flowmeter 16 suddenly reduces its speed of rotation.

[0071] By determining the instant when slowing down occurs it is possible to calculate the amount of water used to fill the empty space V above the coffee puck and start to calculate the real amount of water which will be used for the infusion and therefore determine the end of the pre-infusion step.

[0072] According to a second embodiment, the machine comprises a pressure transducer 24 connected to a control unit (CPU) 60 of the machine. Preferably, the pressure transducer 24 is arranged in the vicinity of the dispensing group, in fluid communication with the coffee boiler (FIGS. 3 and 10b). It could also be in the same position as the flowmeter 24. The connection between the pressure transducer 24 and the control and/or processing unit 60 may be by cable or wirelessly.

[0073] According to the present invention an increase in pressure detected by the pressure transducer 24 is indicative of filling of the empty space above the coffee puck and infusion water supply pipe 6. In other words, when a user starts dispensing a dose of espresso coffee, the pressurized hot water starts to flow freely inside the infusion water supply pipe 6 until the empty space V above the coffee puck is filled. Once this entire volume is filled, the pressure inside the empty space above the coffee puck increases up to a dispensing value. Then the pressurized water starts to pass through the coffee puck and the pressure detected by the pressure transducer 16 is the dispensing pressure generated by the pump 10. The dispensing pressure value could be set as a variable pressure profile during the said dispensing process.

[0074] By determining the instant when the increase in pressure occurs it is possible to calculate the amount of water used to fill the pipes above the coffee puck and start to calculate the amount of water used for the infusion and therefore determine the end of the pre-infusion step.

[0075] According to a third embodiment, the machine 1000 comprises means 29 (FIG. 3) for detecting the variation in weight or mass of the beverage inside the cup (or other container) situated underneath the dispensing group 1003 of the espresso coffee machine 1000. A variation in weight or mass of the beverage inside the cup is indicative of filling of the empty space above the coffee powder puck. In other words, when a user starts dispensing a dose of espresso coffee, the pressurized hot water starts to flow freely inside the infusion water supply pipe 6 until the empty space V above the coffee puck is filled. Once all this volume has been filled, the pressurized water starts to pass through the coffee powder puck and falls into the cup underneath the dispensing group. The instant when the variation in weight or mass occurs is the instant from which the machine is able to define the amount of water used for the infusion and therefore determine the end of the pre-infusion step.

[0076] Preferably, the weighing unit 29 is connected to the control and/or processing unit 60 by cable or wirelessly.

[0077] Obviously, two or more of the aforementioned embodiments could be combined to ensure better precision when determining filling of the empty space above the coffee puck and, consequently, the start the start of the flow of pressurized water for the actual extraction process.

[0078] For example, according to another embodiment, a pressure transducer associated with a flowmeter could be provided. If two or mare devices indicating filling are combined, the control unit of the machine is programmed to manage the two values (pressure and flow values in this case) and identify a single end-of-filling instant (end of pre-infusion and start of dispensing).

[0079] According to embodiments, the value of the parameter indicative of filling of the empty space above the coffee puck may be used for the dispensing operation in progress and/or for subsequent dispensing operations with a self-learning mechanism to improve the detection precision and/or speed.

[0080] FIGS. 7, 8 and 9 show three different flow diagrams relating to the method according to the three main embodiments.

[0081] The flow diagram in FIG. 7 relates to the first embodiment in which the parameter indicative of filling of the empty space above the coffee puck is a flow parameter.

[0082] The method envisages, after starting (100) dispensing of an espresso coffee (single, double, etc.), monitoring (101) a flow value, for example by means of a flowmeter 16 or the like. This is followed by detection (202) of slowing of the flow or a flow value below a predetermined threshold considered to be indicative of the fact that complete filling of the empty space above the coffee powder puck has occurred. From the moment complete filling of the empty space above the coffee powder puck is identified, pressurized water is dispensed (104) in a predetermined amount and/or for a predetermined time with the aim of obtaining a desired amount of espresso coffee in the cup. The pressure of the hot water dispensed before the instant indicative of filling of the empty space may be less than the pressure after this instant. The desired amount of espresso coffee in the cup may depend on the amount of powder used, so as to obtain a desired brew ratio (dilution ratio between water and coffee powder), or on other requirements, for example the weight and/or volume.

[0083] The flow diagram in FIG. 8 relates to the second embodiment in which the parameter indicative of filling of the empty space above the coffee puck is a pressure parameter.

[0084] The method envisages, after starting (200) dispensing of an espresso coffee (single, double, etc.), monitoring (201) a pressure value, for example by means of a pressure transducer 24 or the like. This is followed by detection (202) of a dispensing pressure value or in any case a value above a predetermined threshold considered to be indicative (203) of the fact that compete filling of the empty space above the coffee powder puck has occurred. From the moment complete filling of the empty space above the coffee powder puck is identified, pressurized water is dispensed (204) in a predetermined amount and/or for a predetermined time with the aim of obtaining a desired amount of espresso coffee in the cup. The pressure of the hot water dispensed before the instant indicative of filling of the empty space may be less than the pressure after this instant. The desired amount of espresso coffee in the cup may depend on the amount of powder used, so as to obtain a desired brew ratio (dilution ratio between water and coffee powder), or on other requirements, for example the weight and/or volume.

[0085] The flow diagram in FIG. 9 relates to the third embodiment in which the parameter indicative of filling of the empty space above the coffee puck is a weight or mass parameter.

[0086] The method envisages, after starting (300) dispensing of an espresso coffee (single, double, etc.), monitoring (301) a mass or weight value of a container inside which the beverage will be collected. For example it is possible to use a weighing device 29. A mass or weight value greater than that of the empty container (tare weight) is then detected (302). This value is considered to be indicative of the fact that complete filling of the empty space above the coffee powder puck has occurred and that a part of the beverage has started to collect inside the container (cup). From the moment complete filling of the empty space above the coffee powder puck is identified, pressurized water is dispensed (304) in a predetermined amount and/or for a predetermined time with the aim of obtaining a desired amount of espresso coffee in the cup. The pressure of the hot water dispensed before the instant indicative of filling of the empty space may be less than the pressure after this instant. The desired amount of espresso coffee in the cup may depend on the amount of powder used, so as to obtain a desired brew ratio (dilution ratio between water and coffee powder), or on other requirements, for example the weight and/or volume.