Milk module for preparing milk-based beverages

Abstract

A milk module (1) for producing hot or cold, foamed or non-foamed milk-based beverages from liquid milk includes: a milk line (3) extending from a milk container (4) to a milk dispensing nozzle (5); and an air line (9) extending from an air source and entering the milk line (3). The milk line (3) includes a milk pump (6) for drawing milk from the milk container (4), a flow restrictor (7) disposed on the delivery side of the milk pump (6), and a milk heater (8). The milk module (1) also includes: a proportional air solenoid valve (16) disposed along the air line (9); a pressure sensor (17) disposed along the milk line (3) on the delivery side of the milk pump (6) for measuring and outputting an output indicating the measured pressure of the milk-air mixture in the milk line (3); and an electronic control unit (18) communicating with the pressure sensor (17) to receive its output and communicating 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 programmed to store data representing at least one target pressure curve (P), which indicates the time evolution of the target pressure of the milk-air mixture expected to be obtained in the milk line (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 milk-air mixture measured by the pressure sensor (17) and the target pressure curve (P).

Description

[0001] Cross-reference of related applications

[0002] This patent application claims priority to European Patent Application No. 21203004.3, filed on October 15, 2021, and Italian Patent Application No. 102022000020949, filed on October 11, 2022, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to a milk module for preparing beverages (especially hot or cold, foamed or non-foamed milk) from liquid milk of animal or plant origin.

[0004] This type of milk module is used as a stand-alone unit, or more commonly used in conjunction with or integrated into a machine for preparing coffee-based beverages to form a multi-product preparation unit. Background Technology

[0005] The milk module of the type specified above typically includes a milk line extending from a liquid milk container to a beverage dispensing nozzle; and includes: a milk pump for drawing milk from the container; an air inlet for introducing air into the milk line at the pump's suction side; a foaming device disposed downstream of the milk pump; and a heating device typically disposed between the foaming device and the beverage dispensing nozzle.

[0006] In use, a given amount of air is introduced into the milk stream drawn from the container, and the resulting milk-air mixture is supplied to a foaming device under pressure for foaming, and then heated by a heating device if necessary.

[0007] Typically, foaming devices include flow restrictors, which may be formed, for example, by a fixed nozzle or by a fixed or adjustable throttle valve. Heating devices typically include flow-through heaters, which may be electric heaters or heat exchangers. In other cases, milk or milk-air mixtures are heated by injecting a steam stream into the milk line.

[0008] As is known to those skilled in the art, from a sensory and aesthetic point of view, the amount of air introduced into the milk line represents an indispensable parameter for preparing highly desired effervescent beverages in a cup. Therefore, in recent decades, we have seen an evolution from conventional on / off air control systems that open or close the air inlet via a solenoid valve with a fixed flow rate depending on whether an effervescent beverage is desired, to more complex systems that can proportionally control the introduction of air into the milk line, thus allowing a variable amount of air to be supplied according to the beverage to be prepared.

[0009] One of the most common systems for proportionally controlling air volume is one that draws air from the external environment using a milk pump, and electronically regulates the airflow rate using a proportional solenoid valve before introducing the air into the milk line. Typically, the solenoid valve is controlled by the electronic control unit of the milk module based on various operating parameters (such as the type of milk, the temperature of the cold milk or milk-air mixture, the milk pump speed, etc.) according to closed-loop or open-loop control algorithms well-known in the art.

[0010] Some systems that use proportional solenoid valves to regulate airflow are disclosed exemplarily in the following prior art.

[0011] In EP 3181021 A1 (Steiner Weggis), the air volume is adjusted via a proportional solenoid valve to achieve a given consistency of milk foam. The proportional air solenoid valve is controlled by an electronic control unit based on 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 hot milk-air mixture.

[0012] In EP 3039999 Bl and EP 3040000 Al (Cimbali), the air volume is regulated by a proportional solenoid valve controlled by the electronic control unit according to a predetermined program stored in the electronic control unit.

[0013] In EP 3426110 Bl (Douwe Egberts), the amount of air is regulated by a proportional solenoid valve controlled by an electronic control unit based on the temperature measured by a sensor located near or at the milk inlet.

[0014] In WO 2017155403 A1 (Douwe Egberts), the amount of air is regulated by a solenoid valve controlled by an electronic control unit, depending on the type of beverage to be produced.

[0015] In EP 3277140 A1 (Breville), pressurized air supplied by an air pump is injected into an air jet flow path that is opened in the steam flow path. Summary of the Invention

[0016] The object of this invention is to provide a milk module for preparing beverages, particularly foamed or non-foamed milk, which allows for precise adjustment of the amount of air supplied to the milk line in order to improve the sensory and aesthetic quality of the beverage compared to prior art systems.

[0017] According to the present invention, a milk module for preparing beverages, particularly foamed or non-foamed milk, is provided, as claimed in the appended claims. Attached Figure Description

[0018] The accompanying drawing shows a hydraulic diagram of a preferred embodiment of the milk module of the present invention. Detailed Implementation

[0019] The invention will now be described in detail with reference to the accompanying drawings to enable those skilled in the art to understand, make, and use the invention. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles described can be applied to other embodiments and applications without departing from the scope of protection of the invention as defined in the appended claims. Therefore, the invention should not be considered limited to the described and illustrated embodiments, but must be accorded the widest scope of protection according to the described and claimed features.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly used by those skilled in the art in connection with this invention. In the event of conflict, this description (including the definitions provided) shall be binding. Furthermore, the examples provided are for illustrative purposes only and should not be considered limiting.

[0021] To facilitate understanding of the embodiments described herein, reference will be made to specific embodiments, and specific language will be used to describe these embodiments. The terminology used in this application is for the purpose of describing specific embodiments only and is not intended to limit the scope of the invention.

[0022] In the accompanying drawings, reference numeral 1 generally refers to milk module 1 for producing hot or cold, foamed or non-foamed milk-based beverages from liquid milk of animal or plant origin.

[0023] Depending on its application, milk module 1 can be configured to operate as a stand-alone milk module, or it can be connected to one or more automated beverage preparation machines (e.g., coffee machines) to form an integrated multi-product production unit.

[0024] The milk module 1 includes a milk line 3 extending from the milk container 4 to the milk dispensing nozzle 5 arranged in the cup filling chamber (not shown). The milk container is preferably housed in a cooler (not shown) designed to maintain the milk at a temperature between 3°C and 5°C.

[0025] The milk line 3 includes, in sequence, a milk pump 6 for drawing milk from the milk container 4, a flow restrictor 7 arranged on the delivery side of the milk pump 6, and a milk flow heater 8.

[0026] In different embodiments not shown, the current limiter 7 may be arranged downstream of the milk heater 8.

[0027] Conveniently, the milk pump 6 is a rotary displacement pump, preferably a gear pump.

[0028] The flow restrictor 7 can be formed by a fixed nozzle or by a fixed or adjustable baffle or throttle valve.

[0029] Conveniently, the milk heater 8 is an electric heater, preferably an electromagnetic induction heater.

[0030] In different embodiments not shown, the milk heater 8 may be a heat exchanger or a steam heater to inject steam jets directly into the milk stream or indirectly into the milk stream through heated milk pipes.

[0031] The milk module 1 also includes an air line 9, which extends from an air source (usually the external environment) through an air filter 10 and leads to the milk line 3 at a point on the suction side of the milk pump 6, so that in use, the operation of the milk pump 6 not only draws milk from the milk container 4 but also draws air into the milk line 3.

[0032] In different embodiments, the air line 9 may lead to a point on the milk line 3 on the delivery side of the milk pump 6 (upstream of the flow restrictor 7) and be supplied by an air compressor.

[0033] The flow restrictor 7 limits the local narrowing of the cross-section of the milk line 3 downstream of the milk pump 6, so that during use, the milk-air mixture flowing through it undergoes rapid compression and subsequent rapid expansion, converting the milk-air mixture into foamed milk according to principles known to those skilled in the art.

[0034] The milk module 1 also includes a three-way solenoid valve 11 at the inlet of the milk line 3 to selectively connect the milk line 3 to the milk container 4 in a normal beverage preparation configuration and to the water line 12 in a washing configuration.

[0035] The milk module 1 also includes another three-way diverter solenoid valve 13 downstream of the flow heater 8 to selectively connect the milk line 3 to the milk dispensing nozzle 5 in the beverage preparation configuration and to the wastewater container 14 via the discharge pipe 15 in the washing configuration.

[0036] To regulate the amount of air introduced into the milk line 3, the milk module 1 also includes:

[0037] - A proportional air solenoid valve 16 is arranged downstream of the air filter 10 along the air line 9;

[0038] - Pressure sensor 17, arranged along milk line 3 on the delivery side of milk pump 6, between the delivery side and flow restrictor 7, to measure and output an electrical output indicating the measured pressure of the milk-air mixture downstream of milk pump 6; and

[0039] - An electronic control unit 18, which communicates with pressure sensor 17, particularly electrically connected to pressure sensor 17 to receive its electrical output, and electrically connected to proportional air solenoid valve 16 to provide it with electrical commands, and the electronic control unit is programmed to control the operation of proportional air solenoid valve 16 based on the pressure of the milk-air mixture measured by pressure sensor 17, so that milk module 1 produces a milk-based beverage that is of high quality in terms of both sensory and aesthetics, i.e., the milk-based beverage contains an appropriate amount of milk and the top layer of milk foam has an appropriate height and consistency.

[0040] In different embodiments not shown, the pressure sensor 17 may be arranged downstream of the flow restrictor 7 or downstream of the milk heater 8.

[0041] In another embodiment not shown, the pressure sensor 17 may not be a physical sensor arranged along the milk line 3, but may be a virtual sensor implemented by the electronic control unit 18 to estimate the pressure of the milk-air mixture downstream of the milk pump 6 based on the current absorption of the milk pump 6, and therefore should be measured for this purpose via known available techniques.

[0042] In order to control the operation of the proportional air solenoid valve 16, in one embodiment, the electronic control unit 18 is programmed to:

[0043] - Store data representing at least one target pressure curve P, which indicates the time evolution of the target pressure of the milk-air mixture expected to be obtained in the milk line 3 downstream of the milk pump 6; and

[0044] - The proportional air solenoid valve 16 is controlled in a closed loop based on the deviation between the measured pressure of the milk-air mixture downstream of the milk pump 6, measured by the pressure sensor 17, and the desired target pressure of the milk-air mixture, represented by the target pressure curve P.

[0045] In one embodiment, the target pressure curve P is constant over time, so that the proportional air solenoid valve 16 is controlled to maintain a constant pressure of the milk-air mixture in the milk line 3 downstream of the milk pump 6.

[0046] In different embodiments, the pressure curve P has a development over time such that the proportional air solenoid valve 16 is controlled such that the pressure of the milk-air mixture in the milk line 3 downstream of the milk pump 6 has a time development similar to the target pressure curve P.

[0047] For example, a target pressure curve P with time-varying development may have a trend according to the following broken line, which is formed by a plurality of substantially straight segments, including a first segment with a first duration, wherein the target pressure increases from an initial value (e.g., 1 bar) to a final value (e.g., 4 bar) in a given time interval; a second segment with a second duration, wherein the target pressure remains substantially constant in a given time interval; and a third segment with a third duration, wherein the target pressure returns to the initial value in a given time interval.

[0048] In different embodiments, the electronic control unit 18 is programmed to store data representing different target pressure curves P, each of which can be conveniently associated with a corresponding milk-based beverage, which can be generated by the milk module 1 and selected by a user via a graphical user interface (GUI), wherein the GUI is displayed on a display of an automated beverage preparation machine associated with or integrated with the milk module 1.

[0049] In one embodiment, the electronic control unit 18 is programmed to output electrical commands for the proportional air solenoid valve 16 by applying, for example, a proportional-derivative (PD) controller.

[0050] It should be understood that controllers other than those indicated and which those skilled in the art would consider suitable for this purpose may be used.

[0051] In order to control the operation of the proportional air solenoid valve 16, the electronic control unit 18 is programmed as follows:

[0052] - Compare the electrical output of pressure sensor 17 with the target pressure curve P;

[0053] -As long as the measured pressure of the milk-air mixture downstream of the milk pump 6 deviates from the target pressure by no more than a certain tolerance threshold (e.g., ±0.2 bar), the proportional air solenoid valve 16 will not be adjusted.

[0054] - Conversely, when the measured pressure of the milk-air mixture downstream of the milk pump 6 deviates from the target pressure by more than the aforementioned tolerance threshold, the proportional air solenoid valve 16 is intervened by increasing or decreasing by a percentage amount proportional to the deviation of the measured pressure from the target pressure, depending on whether the measured pressure of the milk-air mixture downstream of the milk pump 6 is lower or higher than the target pressure by more than the aforementioned tolerance threshold.

[0055] In order to compare the electrical output of pressure sensor 17 with the target pressure curve P, electronic control unit 18 is programmed to sample the electrical output of pressure sensor 17 at a given sampling frequency (e.g., per second) and compare the sample of the electrical output of pressure sensor 17 with the corresponding stored value of the target pressure curve P.

[0056] After each adjustment intervention of the proportional air solenoid valve 16, the electronic control unit 18 is programmed to wait for the pressure change interval, and then check whether further adjustment intervention of the proportional air solenoid valve 16 should be performed.

[0057] Based on the description already provided, the advantages that this invention allows for are understandable.

[0058] In particular, the present invention allows the pressure profile of the milk-air mixture downstream of the milk pump 6 to be defined and set, which is reproduced throughout the beverage dispensing process and enables the milk module 1 to produce a high-quality milk-based beverage that is both sensory and aesthetically pleasing, i.e. contains an appropriate amount of milk and has an appropriate height and consistency of milk foam on top.

[0059] In addition, the present invention allows for the identification and concurrent signaling of the absence of milk in the milk line 3 downstream of the milk pump 6, thereby indicating that the milk container 4 is empty.

[0060] In addition, the present invention allows for the diagnosis and signaling of any abnormalities in the milk module (such as milk pump malfunctions).

[0061] Finally, it is clear that various modifications can be made to the described and illustrated embodiments without departing from the scope of the invention as claimed in the appended claims.

[0062] For example, in different embodiments not shown, air can be introduced into air line 9 via a compressed air source (e.g., an air compressor) electronically controlled by electronic control unit 18. In this embodiment, proportional air solenoid valve 16 can be omitted and the amount of air introduced into milk line 9 can be adjusted by appropriately controlling the compressed air source (considered in this example as the speed of the air compressor). Alternatively, proportional air solenoid valve 16 can be maintained and arranged downstream of the compressed air source to finely regulate the amount of air introduced into milk line 3.

[0063] The heater can be arranged along the air line 9 to properly heat the air introduced into the milk line 3.

Claims

1. A milk module (1) for preparing hot or cold, foamed or non-foamed milk-based beverages from liquid milk; The milk module (1) includes a milk line (3) and an air line (9). The milk line (3) extends from the milk container (4) to the milk dispensing nozzle (5), and the air line (9) extends from an air source and leads to the milk line (3). The milk line (3) includes a milk pump (6) for drawing milk from the milk container (4), a flow restrictor (7) disposed on the delivery side of the milk pump (6), and a milk heater (8). The milk module (1) also includes: A proportional air solenoid valve (16) is arranged along the air line (9); a pressure sensor (17) measures and outputs an output indicating the pressure of the milk-air mixture in the milk line (3) downstream of the milk pump (6); and an electronic control unit (18) communicates with the pressure sensor (17) to receive its output and 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 curve (P), which indicates the time evolution of the target pressure of the milk-air mixture expected to be obtained in the milk line (3) downstream of the milk pump (6); and - The proportional air solenoid valve (16) is controlled in a closed loop based on the pressure of the milk-air mixture measured by the pressure sensor (17) and the target pressure curve (P).

2. The milk module (1) according to claim 1, wherein, The pressure sensor (17) is a physical sensor arranged along the milk line (3) on the delivery side of the milk pump (6).

3. The milk module (1) according to claim 1, wherein, The pressure sensor (17) is a virtual sensor designed to measure and output an output indicating the pressure of the milk-air mixture in the milk line (3) downstream of the milk pump (6) based on the current absorbed by the milk pump (6).

4. The milk module (1) according to any one of the preceding claims, wherein, The target pressure curve (P) stored is such that the proportional air solenoid valve (16) is controlled to ensure that the pressure of the milk-air mixture in the milk line (3) downstream of the milk pump (6) develops substantially constantly over time.

5. The milk module (1) according to any one of claims 1-3, wherein, The target pressure curve (P) stored is such that the proportional air solenoid valve (16) is controlled to make the pressure of the milk-air mixture in the milk line (3) downstream of the milk pump (6) develop over time.

6. The milk module (1) according to any one of claims 1-3, wherein, The electronic control unit (18) is also configured to store different target pressure curves (P), each target pressure curve (P) being associated with a corresponding milk-based beverage that can be produced by the milk module (1).

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

8. An automatic beverage preparation machine, comprising a milk module (1) according to any one of claims 1-3.

Images