Milk module for preparing dairy drinks

Abstract

The milk module (1) for preparing beverages from liquid milk, either hot or cold, with or without foaming, comprises a milk flow path (3) extending from a milk container (4) to a milk injection nozzle (5) and an air flow path (9) extending from an air source and opening into the milk flow path (3). The milk flow path (3) comprises a milk pump (6) for drawing milk from the milk container (4), a flow restriction mechanism (7) arranged downstream of the milk pump (6) and a milk heater (8). The milk module (1) further comprises a proportional air solenoid valve (16) arranged along the air flow path (9), a pressure sensor (17) for measuring the pressure of the milk / air mixture in the milk flow path (3) downstream of the milk pump (6) and for providing an output indicative of said pressure, and an electronic control unit (18) in communication with the pressure sensor (17) to receive said output and in communication with the proportional air solenoid valve (16) to control its operation. In order to control the operation of the proportional air solenoid valve (16), the electronic control unit (18) is configured to store data representing at least one target pressure profile (P) which shows the time course of the target pressure of the mixture expected in the milk flow path (3) downstream of the milk pump (6) and to perform closed-loop control of the proportional air solenoid valve (16) based on the pressure of the mixture measured by the pressure sensor (17) and the target pressure profile (P).

Description

[Technical field]

[0001] This application claims priority to European Patent Application No. 21203004.3, filed October 15, 2021, and Italian Patent Application No. 102022000020949, filed October 11, 2022, the entire disclosures of which are incorporated by reference.

[0002] The present invention relates to a milk module for preparing beverages from liquid milk of animal or vegetable origin, whether hot or cold, foamed or not.

[0003] A milk module of this kind may be used as a stand-alone unit or, more generally, may be used in conjunction with or integrated with a machine for preparing coffee beverages to form a multi-product preparation unit. [Background technology]

[0004] A milk module of the kind identified above typically comprises a milk flow path extending from a container of liquid milk to a beverage ejection nozzle, and the following elements: A pump to suck milk out of the container an air inlet allowing the introduction of air into the milk flow passage on the suction side of the pump; A foaming device disposed downstream of the pump. A heating device, typically disposed between the frothing device and the beverage dispenser nozzle.

[0005] In use, a quantity of air is introduced into the flow of milk drawn from the container, and the resulting milk / air mixture is fed under pressure to the frothing device and is then heated, if required, by the heating device.

[0006] The frothing device typically comprises a flow restriction mechanism, for example formed by a fixed nozzle or a fixed or adjustable throttle valve. The heating device typically comprises a flow-through heater, which can be an electric heater or a heat exchanger. Alternatively, the milk / air mixture is heated by injecting a steam flow into the milk flow path.

[0007] As is well known to those skilled in the art, the amount of air introduced into the milk channel is a crucial parameter for the preparation of a frothed beverage in a cup in order to meet high demands, both in terms of taste and aesthetics, and therefore in recent years there has been a progression from older systems based on on-off air control, where the air inlet is opened or closed by a solenoid valve with a constant flow rate depending on whether frothing is being performed, to more advanced systems in which the introduction of air into the milk channel can be proportionally controlled so that the amount of air supplied can be varied depending on the beverage being prepared.

[0008] In one of the most commonly used systems for proportional control of the air volume, outside air is drawn in by the action of a milk pump and the air flow is electronically regulated by a proportional solenoid valve before being introduced into the milk channel. The solenoid valve is usually controlled by an electronic control unit of the milk module based on closed or open loop control algorithms well known in the art. The control is based on various parameters such as the type of milk, the temperature of the cold milk or milk-air mixture, the speed of the milk pump, etc.

[0009] Several systems using proportional solenoid valves to regulate air flow are illustratively disclosed in the following prior art documents:

[0010] In EP 3 181 921 A1 (Stener Weggis) the amount of air is regulated by a proportional solenoid valve in order to obtain a milk froth with a defined viscosity. The proportional solenoid valve is controlled by an electronic control unit on the basis of measurements of several operating parameters, such as the type of milk, the temperature of the milk in the milk container and the temperature of the heated milk / air mixture.

[0011] In EP 3039999 and EP 3040000 (Cimbali) the amount of air is regulated by a proportional solenoid valve which is controlled according to a predetermined program stored in an electronic control unit.

[0012] In EP 3426110 (Douwe Egberts) the amount of air is regulated by a proportional solenoid valve controlled by an electronic control unit based on temperature measured by a sensor placed at or near the milk inlet.

[0013] In WO 2017 / 155403 (Douwe Egberts) the amount of air is regulated by a proportional solenoid valve controlled by an electronic control unit based on the type of beverage being prepared. Summary of the Invention [Problem to be solved by the invention]

[0014] The object of the present invention is to provide a milk module for preparing beverages, in particular dairy beverages, with or without foam, in which the amount of air supplied to the milk channel can be adjusted more precisely than in conventional systems in order to enhance both the flavor and the aesthetics of the beverage. [Means for solving the problem]

[0015] According to the present invention there is provided a milk module for preparing beverages, in particular milk beverages, with or without foaming, as claimed in the accompanying claims. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a flow diagram of a milk module according to a preferred embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described in detail with reference to the accompanying drawings so as to enable those skilled in the art to understand and carry out the invention. Modifications to the described embodiments that are obvious to those skilled in the art, and application of the general principles to other embodiments, are possible without departing from the scope of protection of the invention as defined by the appended claims. Therefore, the present invention should not be limited to the described embodiment examples, but should be accorded the broadest scope of protection based on the characteristics described in the specification and the claims.

[0018] Unless otherwise specified, the technical and scientific terms described herein have the same meaning as commonly used by those skilled in the art to which the present invention pertains. In the event of any conflict, the descriptions and definitions provided herein shall prevail. The examples are provided for illustrative purposes only and should not be construed as being limiting to said examples.

[0019] To facilitate an understanding of the embodiments described herein, reference will be made to certain embodiments and specific terms will be used to describe the embodiments. The terms used herein are used to describe only certain embodiments and are not intended to limit the invention.

[0020] In the attached drawings, reference number 1 designates as a whole a milk module for preparing a milk drink from animal or vegetable milk, said drink being hot or cold and with or without foam.

[0021] Depending on its application, the milk module 1 may be configured to operate as a stand-alone milk module or in connection with at least one automatic beverage preparation machine (such as a coffee machine) to form an integrated unit producing multiple products.

[0022] The milk module 1 comprises a milk channel 3. The milk channel 3 runs from a milk container 4 to a milk injection nozzle 5. The milk container 4 is preferably housed in a cooling device (not shown) so as to keep the milk temperature between 3° C. and 5° C. The milk injection nozzle 5 is arranged in a cup filling chamber (not shown).

[0023] The milk flow path 3 is equipped with a milk pump 6, a flow restriction mechanism 7 and a flow-through milk heater 8 in series. The milk pump 6 sucks milk from the milk container 4. The flow restriction mechanism 7 is arranged downstream of the milk pump 6.

[0024] In an alternative embodiment, not shown, the flow restriction mechanism 7 may be arranged downstream of the milk heater 8 .

[0025] The milk pump 6 is advantageously a rotary positive displacement pump, preferably a gear pump.

[0026] The flow restriction mechanism 7 may be formed by a fixed nozzle or a fixed or adjustable baffle or throttle valve.

[0027] The milk heater 8 is advantageously an electric heater, preferably an electromagnetic induction heater.

[0028] In alternative embodiments not shown, the milk heater 8 can be a heat exchanger or a steam heater, which can either inject a steam flow directly into the milk flow path or indirectly heat the milk flow path with the steam flow.

[0029] The milk module 1 further comprises an air channel 9 which opens from an air source (usually the outside air) through an air filter 10 into the milk channel 3 upstream of the milk pump 6. Thus, in use, operation of the milk pump 6 not only draws milk from the milk container 4 but also draws air into the milk channel 3.

[0030] In an alternative embodiment the air channel 9 may also open into the milk channel 3 downstream of the milk pump 6 and upstream of the flow restriction mechanism 7. The air may be provided by an air compressor.

[0031] The flow restriction mechanism 7 defines a localized narrowing of the cross section of the milk flow passage 3 downstream of the milk pump 6 so that, in use, a mixture of milk and air passing through this section undergoes rapid compression followed by rapid expansion to turn into frothy milk, according to principles well known to those skilled in the art.

[0032] The milk module 1 further comprises a three-way solenoid valve 11 at the inlet of the milk channel 3. The three-way solenoid valve 11 is capable of selecting between a normal beverage preparation configuration in which the milk channel 3 is in communication with the milk container 4 and a cleaning configuration in which the milk channel 3 is in communication with the water channel 12.

[0033] The milk module 11 further comprises a further three-way diverter solenoid valve 13 downstream of the milk heater 8. The three-way diverter solenoid valve 13 is capable of selecting between a normal beverage preparation configuration in which the milk channel 3 communicates with the milk injection nozzle 5 and a cleaning configuration in which the milk channel 3 communicates with a drain container 14 via a drain duct 15.

[0034] In order to regulate the amount of air introduced into the milk channel 3, the milk module 1 further comprises the following elements: A proportional air solenoid valve 16 disposed along the air flow path 9 downstream of the air filter 10 a pressure sensor 17 disposed along the milk flow path 3 downstream of the milk pump 6 and upstream of the flow restriction mechanism 7 to measure the pressure of the milk / air mixture at that location and to provide an electrical output indicative of that pressure; An electronic control unit 18 in communication with (electrically connected to) the pressure sensor 17 and the proportional air solenoid valve 16 The electronic control unit 18 receives the electrical output from the pressure sensor 17 and provides electrical commands to the proportional air solenoid valve 16. The electrical commands are programmed to control the operation of the proportional air solenoid valve 16 based on the pressure of the milk / air mixture measured by the pressure sensor 17. This causes the milk module 1 to prepare a milk drink of high quality in terms of both taste and aesthetics (i.e. containing the correct amount of milk and with a top layer of milk foam of the right height and viscosity).

[0035] In alternative embodiments not shown, the pressure sensor 17 can be arranged downstream of the flow restriction mechanism 7 or downstream of the milk heater 8 .

[0036] In yet another embodiment, not shown, the pressure sensor 17 can be a virtual sensor, realised by the electronic control unit 18, instead of a physical sensor arranged along the milk flow path 3. The virtual sensor estimates the pressure of the milk / air mixture downstream of the milk pump 6 based on the current absorption of the milk pump 6, which is measured using known techniques.

[0037] To control the operation of the proportional air solenoid valve 16, the electronic control unit 18, in one embodiment, is programmed to perform the following operations. storing data representative of at least one target pressure profile P, which indicates the course over time of the target pressure of the milk / air mixture expected in the milk channel 3 downstream of the milk pump 6; Closed-loop control of the proportional air solenoid valve 16 based on the deviation between the pressure of the milk / air mixture downstream of the milk pump 6 measured by the pressure sensor 17 and the target pressure expected by the target pressure profile P.

[0038] In one embodiment, the target pressure profile P is constant in time, whereby the proportional air solenoid valve 16 is controlled to keep the pressure of the milk / air mixture in the milk channel 3 downstream of the milk pump 6 constant.

[0039] In another embodiment, the target pressure profile P varies over time, whereby the proportional air solenoid valve 16 is controlled in such a way that the pressure of the milk / air mixture in the milk channel 3 downstream of the milk pump 6 follows a similar time course to the target pressure profile P.

[0040] For example, the time-varying target pressure profile P may have a piecewise linear trend with a number of linear segments, including a first segment, a second segment, and a third segment. In the first segment having a first time length, the target pressure increases from an initial value (e.g., 1 bar) to a final value (e.g., 4 bar) over a predetermined time interval. In the second segment having a second time length, the target pressure remains substantially constant over a predetermined time interval. In the third segment having a third time length, the target pressure returns to the initial value over a predetermined time interval.

[0041] In another embodiment, the electronic control unit 18 is programmed to store data representing a number of different target pressure profiles P. Each target pressure profile P may be conveniently associated with each dairy beverage producible by the milk module 1. Each target pressure profile P may be selected by a user through a graphical user interface (GUI) displayed on the display of the automatic beverage preparation machine with which the milk module 1 is associated or integrated.

[0042] In one embodiment, a proportional-derivative (PD) controller is implemented, for example, and is programmed to output an electrical command to the proportional air solenoid valve 16 .

[0043] Controllers other than those described above may also be implemented as long as a person skilled in the art can determine that they are suitable for the purpose.

[0044] To control the operation of the proportional air solenoid valve 16, the electronic control unit 18 is programmed to perform the following operations. ·Comparing the electrical output of the pressure sensor 17 with the target pressure profile P. No adjustments are made to the proportional air solenoid valve 16 unless the deviation of the measured pressure of the milk / air mixture downstream of the milk pump 6 from the target pressure exceeds a certain threshold range (e.g. ±0.2 bar). If the deviation of the measured pressure of the milk / air mixture downstream of the milk pump 6 from the target pressure exceeds the above-mentioned threshold range, an intervention is made in the proportional air solenoid valve 16 to increase or decrease the cross-sectional area of ​​the air flow path by an amount (%) proportional to the deviation of the measured pressure from the target pressure, depending on whether the measured pressure is higher or lower than the target pressure.

[0045] To compare the electrical output of the pressure sensor 17 with the target pressure profile P, the electronic control unit 18 is programmed to sample the electrical output of the pressure sensor 17 at a predetermined sampling frequency (e.g., every second) and compare the obtained values ​​with corresponding stored values ​​of the target pressure profile P.

[0046] The electronic control unit 18 is programmed to wait a pressure transient period each time an adjustment intervention is made to the proportional air solenoid valve 16 before checking whether a further adjustment intervention should be made.

[0047] Based on the above description, the advantages provided by the present invention can be understood.

[0048] In particular, the invention makes it possible to set a pressure profile of the milk / air mixture obtained downstream of the milk pump 6, which pressure profile is reproduced throughout the injection of the beverage and enables the milk module 1 to produce a dairy beverage of high quality, both in terms of taste and aesthetics (i.e. containing the correct amount of milk and with a top layer of milk foam of the correct height and viscosity).

[0049] Additionally, the invention makes it possible to identify and signal the absence of milk in the milk flow path 3 downstream of the milk pump 6, which indicates that the milk container 4 is empty.

[0050] Furthermore, according to the present invention, it is possible to diagnose and notify abnormalities in the milk module (such as a breakdown in the milk pump).

[0051] It will be apparent that various modifications can be made to the embodiments described above without departing from the scope of the present invention as set forth in the appended claims.

[0052] For example, in an alternative embodiment not shown, air may be introduced into the air flow path 9 by a compressed air source (such as an air compressor) electronically controlled by the electronic control unit 18. In this case, the proportional air solenoid valve 16 may be omitted. The amount of air introduced into the air flow path 9 may be regulated through suitable control of the compressed air source (e.g. air compressor speed control). Alternatively, the proportional air solenoid valve 16 may remain and be located downstream of the compressed air source to fine tune the amount of air introduced into the milk flow path 3.

[0053] A heater may be positioned along the air flow path 9 to appropriately heat the air introduced into the milk flow path 3 .

Claims

1. A milk module (1) for preparing beverages from liquid milk, regardless of temperature and whether it is frothed or not, comprising: a milk channel (3) extending from a milk container (4) to a milk injection nozzle (5); an air flow path (9) extending from an air source and opening into the milk flow path (3); It is equipped with The milk channel (3) a milk pump (6) for sucking milk from the milk container (4); a flow restriction mechanism (7) disposed downstream of the milk pump (6); Milk heater (8) and It is equipped with a proportional air solenoid valve (16) disposed along the air flow path (9); a pressure sensor (17) for measuring the pressure of the milk / air mixture in the milk flow path (3) downstream of the milk pump (6) and for providing an output indicative of said pressure; an electronic control unit (18) in communication with the pressure sensor (17) to receive the output and in communication with the proportional air solenoid valve (16) to control its operation; It also has To control the operation of the proportional air solenoid valve (16), the electronic control unit (18) storing data representative of at least one target pressure profile (P) which indicates the time course of the target pressure of the mixture expected in the milk channel (3) downstream of the milk pump (6), a closed-loop control of the proportional air solenoid valve (16) based on the pressure of the mixture measured by the pressure sensor (17) and the target pressure profile (P); It is configured as follows: Milk module (1).

2. the pressure sensor (17) is a physical sensor located along the milk flow path (3) downstream of the milk pump (6); A milk module (1) according to claim 1.

3. the pressure sensor (17) is a virtual sensor that measures the pressure of the mixture in the milk channel (3) downstream of the milk pump (6) based on the current absorbed by the milk pump (6) and provides an output indicative of said pressure; A milk module (1) according to claim 1.

4. said target pressure profile (P) is stored so that said proportional air solenoid valve (16) is controlled in such a way that the pressure of the mixture in the milk channel (3) downstream of the milk pump (6) exhibits a substantially constant time course, A milk module (1) according to any one of claims 1 to 3.

5. the target pressure profile (P) is stored so that the proportional air solenoid valve (16) is controlled to indicate the time course of the pressure of the mixture in the milk channel (3) downstream of the milk pump (6), A milk module (1) according to any one of claims 1 to 3.

6. the electronic control unit (18) is configured to store a plurality of different target pressure profiles (P), each associated with a milk drink producible by the milk module (1); A milk module (1) according to any one of claims 1 to 3.

7. The electronic control unit (18) is configured to control the proportional air solenoid valve (16) by implementing a proportional-derivative (PD) controller. A milk module (1) according to any one of claims 1 to 3.

8. Equipped with a milk module (1) according to any one of claims 1 to 3, Automatic beverage preparation machine.

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