Machine for preparing beverages and method for controlling the delivery of beverages in the machine

Abstract

The present invention relates to a machine for preparing beverages, comprising a pressurized water source; a boiler for heating water; an infusion unit comprising an infusion chamber; a hydraulic circuit connecting the pressurized water source with the boiler and the infusion unit fluid; a control unit suitable for controlling the delivery of beverages from the infusion chamber, characterized in that it also includes: a variable flow valve and a valve drive device for driving the variable flow valve, the variable flow valve being arranged on the hydraulic circuit upstream of the infusion chamber, the valve drive device comprising a manually operable device, wherein the manually operable device is combined with a display suitable for displaying the position of the manually operable device relative to a path and sending a signal indicating the detected position to the control unit, wherein the manually operable device is an image visible on the display, and the variable flow valve is operated by changing the position of the image on the display.

Description

[0001] This invention patent application is a divisional application of the invention patent application with international application number PCT / IB2018 / 058139, international application date October 19, 2018, application number 201880067453.2 entering the Chinese national phase, and name “Machine and method for preparing beverages”. Field of the Invention

[0002] The present invention relates to a machine and a method for preparing a beverage, in particular coffee, by infusion. In particular, the present invention relates to a machine for preparing coffee for professional use, such as for restaurants, bars, hotels, etc.

[0003] In the present application, the term "infusion" refers to a machine that allows the production of a beverage, in particular coffee, by means of water, preferably hot water and pressurized water, through at least one powdered raw material, in particular coffee, contained in an infusion unit. The infusion unit comprises an infusion chamber in which the powdered coffee or other raw material is arranged, an inlet duct for the hot water, an outlet duct for the beverage and a filter for confining the raw material in the infusion chamber.

[0004] These machines also comprise a hydraulic circuit connecting a water source, usually originating from a water supply network, at least one pump, at least one boiler for heating the water and producing steam, and means for controlling the water supply to the infusion chamber. In particular, according to the invention, the machine is of the type comprising a control unit which, together with sensors and valves, forms part of a system suitable for regulating, in particular for setting, the water flow rate through the raw material in the infusion chamber.

[0005] Known prior art

[0006] In the known art, there are infusion machines for preparing and delivering beverages by controlling the water flow through an infusion chamber. Generally, the known machines attempt to solve the problem of water flow control during the infusion step by means of a solution that fully manages the flow in an automatic way through a control unit of the machine. Essentially, this control is obtained by measuring the values ​​of the flow rate and / or pressure of the water entering the infusion chamber and by varying these values ​​so that its curve follows a predetermined curve stored in the control unit.

[0007] An example of such a system is described in EP2314182 of Gruppo Cimbali, which describes a coffee machine comprising a water pressure regulation system having a pressure sensor arranged on a hydraulic circuit and placing a pump in communication with an infusion assembly. The sensor is arranged between the heating chamber and the delivery duct of the infusion chamber. The hydraulic pump is operated electronically by a control unit so as to regulate the outflow of water as a function of the measured delivery pressure value. EP2314183, also of Gruppo Cimbali, relates to a flow control based on circuit pressure measurement; the regulation is carried out by acting on a hydraulic variable flow valve which is controlled to vary the flow at the outlet of the valve itself. In both cases, the control is automatic and performed by the machine.

[0008] EP2490580 of La Marzocco describes a machine comprising one or more operating units, characterised in that there is a system for controlling and regulating the parameters of the soaking. Each operating unit also has a variable speed pump and manual variation means, in particular a rheostat controlled by a manually operable lever, to vary the water pressure during the soaking. The rheostat controls the operation of the variable speed pump.

[0009] The same teachings are described in an online publication published on the website Home-barista.com on October 13, 2009 and obtained from http: / / www.home-barista.com / espresso-machines / pressure-profiling-with-fluid-o-tech-tmfr-pump-or-wholesale-copying-greg-scaces-ideas-t12179.html.

[0010] Document US Pat. No. 4,858,522 to Simac-Castelli describes a rheostat connected to a user-operable handle which allows controlling the amount of coffee to be dispensed by controlling the duration of delivery.

[0011] US9364117 and US9433318 for Seattle Espresso Machine describe a system, method and apparatus for producing coffee by water flow regulation. The method provides a pre-infusion step, in which coffee powder is slowly moistened by a first volume of hot and pressurized water delivered at a first flow rate value. This is followed by a coffee extraction step, the flow rate value of which is greater than the flow rate value of the pre-infusion step. Different valves and paths through which water flows are provided to regulate the flow rate. Thus, the barista can regulate the pressure, capacity and water flow by acting on at least one valve. In particular, the machine is provided with a brewing handle that can be used to operate at least three different delivery modes: an "off" setting (flow rate equal to zero), a first flow rate value for the pre-infusion step and a second flow rate value for the extraction step. In these patents, the flow rate is varied by using a variable number of conduits for supplying water to the infusion chamber.

[0012] As mentioned above, the water supplied to the infusion chamber is associated with predetermined pressure and flow rate curves and values ​​in known control systems. The main drawback of similar controls is that they are typical of a "Dumb Artificial Intelligence" form of control, in which the machine is associated to an immutable program that follows a pressure curve, regardless of the consequences that this action has on the delivery of the beverage. For example, by following a predetermined pressure curve, the desired flow rate curve may not be obtained under certain conditions, and vice versa. This fact is often associated with a failure to correct problems encountered during the delivery of the beverage.

[0013] Another problem of the known machine is related to the complexity of the control system, which translates into rigidity of the system and high machine costs.

[0014] The object of the present invention is to solve the above-mentioned problems and to provide a machine and a method for delivering beverages that are easy to implement and maintain. Another object of the present invention is to obtain a machine and a method that allow flexible and intelligent control of the infusion step during the delivery of the beverage and in particular to adapt the flow rate, if necessary, to the specific delivery conditions. SUMMARY OF THE INVENTION

[0015] These and other objects are achieved by the machine and method of the present invention. Further features / aspects of the present invention are described below. In addition, it should be noted that, according to the present invention, what is described and / or claimed herein with reference to the machine can be applied to the method, and vice versa.

[0016] According to the invention, a machine for preparing a beverage, in particular coffee, by percolation comprises: a source of pressurized water; a water heating boiler; an infusion unit comprising an infusion chamber; a hydraulic circuit fluidically connecting the source of pressurized water to the boiler and the infusion unit; a control unit adapted to control the delivery of the beverage from the infusion chamber. The machine is characterized in that it also comprises a variable flow valve and means for actuating the valve, the valve being arranged on the hydraulic circuit upstream of the infusion chamber; the valve actuation means comprising a manually operable device.

[0017] The term "variable flow valve" is intended to define any hydraulic valve with a variable flow rate control, i.e. a valve capable of varying the flow rate of water through the valve within a range of values ​​between a closed valve (0% flow) and a fully open valve (100% flow). Preferably, the valve is an electric valve. A suitable valve is, for example, a proportional electric valve, by means of which the flow rate of the fluid through the valve can be adjusted between 0% and 100% of the maximum nominal flow rate by varying the electrical signal. Different types and / or shapes of valves, in particular cut-offs suitable for causing a change in the water channel section, can be used. For example, a needle valve can be used. The valve can also be operated by known means, for example, according to a possible embodiment, a stepper motor can be used.

[0018] The variable flow valve is arranged upstream of the infusion chamber. In one embodiment, the valve is a proportional electric valve positioned between the pump and the boiler. In another embodiment, the valve is arranged between the boiler and the infusion chamber.

[0019] The term "manually operable device" refers to any device that can be directly operated by a barista or other user. In other words, the term means that the control of the valve to adjust the water flow rate is performed manually rather than automatically as in the prior art. In other words, according to one aspect of the invention, the valve is controlled by the device, which is manually operated by the user rather than operated by control logic, in particular by feedback control. In a preferred embodiment of the invention, a lever is used, which is mounted on a support and is movable to rotate in a direction for opening the valve and in an opposite direction for closing the valve. According to the invention, other devices such as throttles, joysticks and similar rotatable or linearly movable devices can be manually operated and used. Manually operable devices also include images visible on touch devices such as touch screens or touch pads, and similar devices suitable for displaying variable flow valve opening indicators; whether manually or not, the visualized image can be translated or changed by the operator on the display so as to occupy different "positions" on the screen. In other words, the valve opening can be changed by sliding a finger on the surface of the touch pad, such as sliding the image across the screen. Touch devices that can be used for this purpose are known in the known art.

[0020] The infusion chamber is generally formed by a part of the infusion unit which delivers the water and is arranged on the machine in conjunction with a filter holder which, in use, contains coffee or other raw material and is mounted on the water delivery part. In one embodiment, the infusion chamber comprises a capsule. In one embodiment, the infusion chamber comprises a cylinder inside which at least one piston is movable; this embodiment can be used in so-called vending machines or HoReCa machines.

[0021] According to one aspect of the invention, the machine further comprises at least one flow rate sensor and / or at least one pressure sensor, which are adapted to detect and thereby measure at least one flow rate and / or pressure value. According to one aspect of the invention, the at least one flow rate sensor and / or at least one pressure sensor are therefore adapted to generate a flow rate and / or pressure measurement signal indicative of the detected flow rate and / or pressure value. In other words, according to one aspect of the invention, the at least one flow rate sensor and / or at least one pressure sensor detects a flow rate and / or pressure value within the hydraulic circuit of the machine, thereby generating a flow rate and / or pressure measurement signal. Preferably, the sensor is mounted on a conduit of the hydraulic circuit, and more preferably positioned between the water source and the boiler. The one or more sensors are connected to a control unit.

[0022] According to one embodiment of the invention, the one or more measurement signals generated during beverage delivery may be visible on a screen or display, preferably in the form of a graph or curve of the flow rate and / or pressure of beverage delivery. It should be noted that the signal related to the pressure value may be used to generate any alarm signal if the pressure value exceeds a safety threshold.

[0023] According to one embodiment of the invention, said manually operated means of the flow regulating valve are combined with a device suitable for detecting the position occupied by said means relative to a plurality of possible positions along the path and for sending a signal indicating the detected position to the above-mentioned control unit. The control unit is connected to the variable flow valve and operates said valve as a function of the position detected for the manually operated means.

[0024] Preferably, the position detection device is a potentiometer or a rheostat connected to the control unit. In a preferred embodiment, the manually operated means comprises a rotatable lever in combination with a potentiometer, for example a circular potentiometer, but other embodiments of the potentiometer are not excluded. As mentioned above, circular or linear potentiometers or rheostats can be used, as well as soft potentiometers and potentiometers of the touch type, by means of which pressure can be applied by the finger of the user (i.e. the barista).

[0025] According to an aspect of the invention, the machine comprises a storage unit to store flow rate and / or pressure profiles detected by the aforementioned sensor during beverage delivery.Preferably, the aforementioned control unit is adapted to process a plurality of profiles to display an average delivery profile.

[0026] According to a further aspect of the invention, the machine comprises a memory unit in which the position of the manual device detected by the potentiometer during beverage delivery is stored. Preferably, the aforementioned control unit is adapted to process a plurality of curves related to the position of the lever during various deliveries to display an average position curve which can be used, for example, as a potential reference during delivery.

[0027] According to one aspect of the invention, the control unit is adapted to store the voltage values ​​supplied to the valve, preferably a servo-valve or an electric valve, as a function of the position occupied by the lever during beverage delivery. Thus, the control unit can process a plurality of curves relating to the position of the valve during a single delivery to display an average position curve which can be used, for example, as a possible reference during delivery.

[0028] The present invention also relates to a method for delivering a beverage from a machine having at least some of the above-mentioned characteristics, the method comprising the following steps: supplying water to an infusion component, the infusion component comprising an infusion chamber containing at least one raw material for producing the beverage; delivering the beverage from the infusion chamber; the method comprising: controlling the flow of water supplied to the infusion chamber by means of a variable flow valve, for example, characterized in that the opening of the variable flow valve is controlled by at least one manually operable device to change the flow rate of the beverage during the delivery step.

[0029] According to one aspect of the invention, the position of the manual device corresponds directly or indirectly to the water flow rate through the variable flow valve; when the position of the manual device changes, the flow rate through the valve also changes. Preferably, the relationship between the position of the manual device and the flow rate is indirect. In one embodiment, the machine provides information about the water flow rate through a display; in another embodiment, or in addition to the previous embodiment, the flow information can be visually obtained by observing the delivered beverage.

[0030] According to one aspect of the invention, the manual device is a lever combined with a potentiometer or a rheostat. The method is arranged such that the position of the lever is detected by means of the potentiometer or the rheostat and said position is transmitted to a control unit; the control unit is connected to a variable flow valve and operates said valve as a function of the detected position of the lever. The lever is usually moved in a continuous manner in one direction or in opposite directions; the opening of the variable flow valve corresponds to each position occupied by the lever: the control unit detects the position of the lever and varies the opening of the valve accordingly.

[0031] In another aspect of the invention, the manually operable device is a digital or "virtual" device. In particular, the device is an icon or image indicating the opening of the valve: the image is visible on a device comprising a touch screen; in this embodiment, the method is configured to manually change the position of the image / indicator with at least one finger or a capacitive stylus, and to operate the valve according to the position of the indicator on the display.

[0032] According to one aspect of the invention, the method comprises the steps of detecting (and thereby measuring) flow rate and / or pressure values ​​in the hydraulic circuit during delivery, and visualizing these values ​​on a display during delivery, preferably in the form of a pressure and / or flow rate curve generated during delivery. It should be noted that this aspect of the method of the invention differs from the above-mentioned prior art, which teaches to construct a pressure or flow rate curve before delivering the beverage, and to automatically change the detected pressure or flow during delivery to follow a predetermined curve.

[0033] According to one aspect of the invention, the display displays both an image (i.e., an indicator) of the manually operable device and at least one of the aforementioned flow rate or pressure values. This can facilitate the control of the variable flow valve by the barista.

[0034] The invention has many advantages. In particular, the machine and method allow the delivery of beverages without being restricted to fixed parameters that machines of known art must follow. In this way, the delivered beverages can be customized and improved. Furthermore, the machine is reliable and easy to manage for the user, the barista. Brief introduction of the attached figure

[0035] These and other advantages of the invention will become more apparent from the following description and the accompanying drawings, provided by way of example and not limitation, in which:

[0036] Figure 1 A possible embodiment of the machine according to the invention is schematically shown;

[0037] Figure 2 Schematically shows another possible and alternative embodiment of a machine for preparing beverages according to the invention, in which a bypass duct is present;

[0038] Figure 3 Another possible and alternative embodiment of a machine for preparing beverages according to the invention is schematically shown, wherein there is a pump supplying water to the delivery assemblies of the machine, wherein each delivery assembly is provided with its own valve for controlling the flow rate.

[0039] Mode for carrying out the invention

[0040] refer to Figure 1, shows a machine comprising three beverage delivery assemblies 2, 2a, 2b. In the embodiment shown, each beverage delivery assembly 2-2b is provided with its own pump 5; it should be noted that there may also be a single pump supplying pressurized water to the three delivery assemblies, such as Figure 3 The following description will refer to one of the three delivery components, but the description is also applicable to similar components present in the machine.

[0041] The machine 1 of the invention comprises a water source 3 connected to a pump 5 for supplying pressurized water to Figure 1 and 3 The hydraulic circuits 20a-20c and Figure 2 20a-20e in the hydraulic circuit 20a-20e. The machine further comprises at least one boiler 4 for heating water, at least one infusion unit 6, the infusion unit 6 comprising an infusion chamber 7. The hydraulic circuit fluidically connects a pump 5 to the boiler 4 and the infusion unit 6. The machine further comprises a control unit 8 adapted to control the delivery of the beverage from the infusion chamber. The control is at least partly performed by a variable flow valve 9 arranged on the hydraulic circuit upstream of the infusion chamber 7; the valve 9 is driven directly or preferably indirectly by means comprising a manually operable device indicated in the figures with the reference numeral 10.

[0042] The variable flow valve 9 is preferably a proportional electric valve connected to the control unit 8. The machine preferably also comprises at least one of a flow rate sensor 11 or a pressure sensor 12, preferably arranged between the pump 5 and the boiler 4. A check valve 13 may also be present in this section of the circuit.

[0043] The manually operable device 10 for actuating the proportional valve 9 is combined with a further device 14 adapted to detect the position of the manually operable device relative to the path and to send to the above-mentioned control unit a signal indicative of the detected position of the device 10. In dependence on the signal indicative of the position of the device 10, the valve 9 is actuated to vary the flow rate of water therethrough.

[0044] exist Figure 1 In the possible embodiment shown in , the manually operable device 10 comprises a lever rotatable between a plurality of positions, preferably in a continuous manner; in this embodiment, the further device 14 for detecting the position of the lever comprises a potentiometer or a rheostat associated with the lever and connected to the control unit 8. In this embodiment, the lever moves and changes a value detected by the potentiometer, which value is associated with one of a plurality of positions of the lever, schematically indicated with reference numerals 10a and 10b, and which is read by the control unit 8. The valve 9 is actuated by the control unit 8 to vary the flow rate of the water passing therethrough, depending on the value read by the potentiometer, i.e. on the position 10a-10b assumed by the lever according to the selection made by the barista acting on the lever.

[0045] The machine according to the invention is preferably provided with a display 16 connected to the control unit 8. As mentioned above, the flow sensor and the pressure sensor (if the latter is present) are connected to the control unit 8 and are adapted to generate flow rate and pressure measurement signals, respectively, which are read by the control unit 8. The signals generated and read represent the flow rate and pressure during the beverage delivery. These values ​​can be visualized on the display 16 in the form of a graph or curve 21. It should be noted that according to one aspect of the invention, the control unit 8 does not use the flow rate and / or pressure values ​​to perform feedback control, because, as mentioned above, the valve 9 is controlled according to the position of a manually operable device (e.g. a lever manually operated by a user).

[0046] Instead of or in addition to the use of a physical device such as the aforementioned lever, the invention offers the possibility of using a manual operating device of digital or virtual type to actuate the valve 9 . Figure 1 and Figure 2 An embodiment is shown which comprises a physical manual device (lever in combination with a rheostat) and a digital manually operable device indicated by reference numeral 17 on a display 16. In this embodiment, the manually operable device is an image or icon which serves as a valve actuation indicator and which can be visualized on a touch device, such as a touch screen. The valve 9 is operated by changing the position of the indicator along a path 18 on the touch device. Figure 1 In the embodiment, the entire display 16 is a touch device, but the display can also be separated from the touch screen.

[0047] In one embodiment, the machine comprises a storage unit 19 for storing at least one data selected from the following: the position of said manually operable device 10 or 17, the pressure value in the hydraulic circuit, the flow rate value in the hydraulic circuit. If desired, the control unit is programmable to generate and store at least one curve of said position of the manually operable device 10 or 17; the generated curve can be visualized on the display 16 before, during and after the delivery of the beverage. It is also possible to generate, store and finally display pressure and / or flow rate curves on the display 16.

[0048] Figure 2 Shows Figure 1 A variation of the embodiment in which the difference lies in that the valve 9 is positioned on a bypass duct 20e which leaves from a portion 20b of the hydraulic circuit downstream of the pump 5 (with respect to the direction of water flow) and joins a portion 20a of the hydraulic circuit upstream of the pump 5.

[0049] Figure 3A further possible embodiment of the invention is shown, in which the machine is provided with a single pump 5 feeding a hydraulic circuit which brings water to the respective infusion chamber. A valve 9 is provided downstream of the pump 5 and arranged in a row on each hydraulic circuit which brings water from the single pump 5 to each infusion chamber. Also in this embodiment, the position of the device 10 allows each valve 9 to be actuated by varying the water flow rate through each valve 9. For example, the position value of the device 10 is appropriately converted into a signal which is sent, for example, by the control unit 8 to the valve 9, thereby varying the water flow rate through this valve 9.

[0050] The operation of the above-mentioned machine for controlling the delivery of beverages according to the method of the present invention is arranged to control and thereby set the water flow rate supplied to the infusion chamber by means of a variable flow valve 9, and to control the opening of the variable flow valve 9 by means of at least one device 10 or 17, which can be manually operated by a barista or a general user to change the flow rate of the beverage, for example, during the beverage delivery step, i.e., the flow rate can be changed during the delivery of the beverage.

[0051] During delivery, at least one position of a device manually operable by the barista is detected and a control unit connected to the variable flow valve 9 adjusts the degree of opening or closing of the valve according to the detected position of the manual device. In this way, the barista controls the flow rate of water during the production of a beverage, such as coffee, and can change the infusion conditions and therefore the type and quality of the beverage by manually, in some cases continuously, moving a lever or image or equivalent device.

[0052] As can be seen above, the method may comprise the steps of detecting a plurality of positions occupied by a device (lever, image on a touch screen or other) operated by the barista during the delivery of a beverage, storing these positions and optionally generating one or more position profiles. This allows the barista to identify the best position, i.e. the best profile, based on a quality assessment of the beverage delivered from time to time. Thus, the barista can learn from experience and from the deliveries already performed to improve the next delivery. Naturally, the data acquired from the control unit can be called up and processed.

[0053] Furthermore, the method provides the possibility to detect pressure and / or flow rate values ​​in the hydraulic circuit during delivery and to generate a plurality of pressure and / or flow rate curves indicating the respective values ​​during delivery. In other words, during the delivery itself, the flow rate and / or pressure performance of the delivery can be visualized on a display practically in real time. As mentioned, the detected curves or values ​​are preferably not used by the control unit to control the water flow through the valve 9.

[0054] In one possible embodiment, the display is touch-sensitive or includes a touch screen component, the valve is a proportional valve, the device manually operated by the barista is a lever combined with a rheostat, and the display shows the water flow rate and / or pressure value.

[0055] Another object of the present invention is a storage device suitable for being read by a computer and / or a control unit, said device comprising instructions which, once read by the control unit of the machine of the present invention, cause the machine to execute the steps of the method of the present invention.

Claims

1. A machine (1) for preparing a beverage, comprising: A pressurized water source; A boiler (4) for heating water; an infusion unit (6), the infusion unit comprising an infusion chamber (7); a hydraulic circuit (20a-20e), the hydraulic circuit fluidically connecting the pressurized water source with the boiler and the infusion unit; a control unit (8), the control unit being adapted to control the delivery of a beverage from the infusion chamber, characterised in that it also comprises: a variable flow valve (9) and a valve drive device for driving the variable flow valve, the variable flow valve being arranged on the hydraulic circuit upstream of the infusion chamber (7), the valve drive device comprising a manually operable device (17), wherein the manually operable device (17) is combined with a display (16) adapted to display the position of the manually operable device relative to a path (18) and to send a signal indicative of the detected position to the control unit (8), wherein the manually operable device is an image visible on the display (16) and the variable flow valve (9) is operated by changing the position of the image on the display (16).

2. The machine according to claim 1, characterized in that The position of the variable flow valve (9) is selected between the boiler (4) and the infusion chamber (7) or between the pump (5) and the boiler (4).

3. The machine according to claim 1, characterized in that The variable flow valve (9) is a proportional electric valve.

4. The machine according to claim 1, characterized in that It also comprises at least one flow rate sensor (11) adapted to detect the flow rate and / or at least one pressure sensor (12) adapted to detect the pressure value.

5. Machine according to any one of the preceding claims, characterised in that A storage unit (19) is included for storing at least one set of data selected from the following: the position of the manually operable device (17), the pressure value in the hydraulic circuit, the flow rate value in the hydraulic circuit, or a combination thereof.

6. The machine according to claim 5, characterized in that The control unit (8) is programmable to generate at least one curve (21) of the positions, and the display (16) is adapted to display the curve.

7. A method for controlling the delivery of a beverage in a machine (1) according to any one of claims 1 to 6, the machine comprising a pressurized water source, a boiler (4) for heating water, an infusion unit (6) comprising an infusion chamber (7), a hydraulic circuit (20a-20e) fluidically connecting the pressurized water source, the boiler and the infusion unit, a control unit (8) adapted to control the delivery of the beverage from the infusion chamber (7), a variable flow valve (9) and valve drive means for driving the variable flow valve, the variable flow valve being arranged on the hydraulic circuit upstream of the infusion chamber (7), the valve drive means comprising a manually operable device (17), the method comprising: The water supply to the infusion chamber (7) is controlled by the variable flow valve (9), characterised in that the opening of the variable flow valve (9) is controlled by the manually operable device (17) to vary the flow rate of the beverage during the delivery step.

8. The method according to claim 7, characterized in that The following steps are involved: The position of the manually operable device (17) is detected, and wherein the control unit (8) is connected to the variable flow valve (9) and operates the variable flow valve in dependence on the detected position of the manually operable device (17).

9. The method according to claim 7, characterized in that: The following steps are involved: The pressure and / or flow rate values ​​in the hydraulic circuit are detected, and a plurality of curves (21) of the pressure and / or flow rate are generated.

10. The method according to claim 9, characterized in that At least one of the curves (21) is displayed in a display (16).

11. The method according to any one of claims 7 to 9, characterized in that: The manually operable device is an image visible on a device comprising the display (16), and the variable flow valve (9) is operated by changing the position of the image.

12. The method according to claim 11, characterized in that The image is displayed on the display (16).

13. A storage device suitable for being read by a computer and / or a control unit, the storage device comprising instructions which, once read by a control unit of a machine according to any one of claims 1 to 6, cause the machine to execute a method according to any one of claims 7 to 12.

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