Method for generating in particular milk foam, and also a device for implementing the method

Abstract

In a method for generating in particular milk foam, superheated steam is supplied along with air, and with a controllable quantitative output, to a milk-containing receptacle (12) by a steam device, which dips into the milk (13) in the receptacle (12). During the heating-up stage, the temperature of the milk is measured and evaluated by at least one temperature probe (18) within the receptacle (12). When the stage of heating up the milk (13) contained in the receptacle (12) begins, steam is supplied with a predetermined quantitative output, and the supply of air is switched on. Once steam supply has begun, a difference in temperature (ΔT) of the measured milk temperatures (T1, T2) between a predetermined first and second defined point in time (t1, t2) is established for these points in time. On the basis of the difference in temperature (ΔT), at least the superheated steam is supplied either with the same quantitative output or with an altered quantitative output, and is switched off before or when the final temperature (T3) of the milk (13) is reached.

Description

[0001] Method for producing in particular milk foam, as well as a device for carrying out the method

[0002] The invention relates to a method for producing, in particular, milk foam and to a device for carrying out the method according to the preamble of claim 1 or claim 11.

[0003] In a method according to document EP 3 273 828 B1, particularly for preparing beverages containing milk foam in a coffee machine or similar device, the media steam and compressed air are fed to the milk via a steam lance immersed in the milk, wherein the two media steam and air are fed to the milk through at least two supply lines that are separate from each other up to the outlet from the lance. Preferably, only steam is fed through one line at the required steam velocity, while a steam-air mixture is fed through the other line to enrich the milk with the necessary amount of air.The steam and air supply are controlled depending on time and temperature, whereby when starting the machine in a first phase both the steam and the steam-air supply line are active, while in a second phase the steam-air supply line is inactive and only steam is supplied to the milk through the steam supply line.

[0004] The publication WO 2019 / 015865 A1 describes a method for manual

[0005] Controlling an operating unit for dispensing steam from a coffee machine is disclosed. Steam is adjusted by a manually adjustable operating element, starting from a locked basic position in which no steam is dispensed, in one direction into locked positions for dispensing specific amounts of steam, in which the amount of steam changes upon adjustment. The operating unit comprises a fixed sleeve, an outlet head adjustably held thereon with a steam lance attachable to it, and an adjustable sleeve with the operating element. Locking means are provided by which the sleeve with the operating element can be locked in this basic position(s), or adjusted in the opposite direction, in which the amount of steam can be varied almost continuously.This allows the milk foam to be created depending on the desired dispensing method for the amount of milk in a cup or similar item. However, this depends on the operator's manual handling, and this can result in variations in the milk foam produced.

[0006] Based on these proven methods explained above, the object of the invention is to create a method for producing, in particular, milk foam, by means of which milk foam can be produced automatically via a steam device immersed in the milk, in which the steam and air supply can be easily regulated or controlled until the predetermined final temperature is reached.

[0007] This object is achieved according to the invention by the features of claim 1.

[0008] In the method according to the invention, when producing milk foam, steam is supplied at a predetermined output when heating up the milk filled in the container starts, and the air supply is switched on at the beginning or after a certain point in time for the milk foam production, wherein after the start of the steam supply, a temperature difference between at least a predetermined first and a second fixed point in time is determined, wherein on the basis of the determined temperature difference, at least the steam is supplied either at the same or with a changed output, and this steam supply and the air supply are switched off before or when the final temperature of the milk is reached.Instead of or in addition to calculating the temperature difference, a temperature gradient is determined, whereby on the basis of the temperature gradient at least the steam is switched off either with the same or with a changed output and this steam and the air supply are switched off before or when the final temperature of the milk is reached.

[0009] With this method according to the invention, automated milk foam production is made possible by simply measuring the milk temperature, evaluating it and subsequently controlling the steam and air supply, without an operator having to move the container up and down during the steam supply or manually adjust the amount of steam.

[0010] It is very advantageous to introduce the hot steam into the milk in the container at a reduced, preferably constant, rate when heating begins. This prevents excessive heating when the milk quantity in the container is small.

[0011] The temperature difference at which the first time is subtracted from the second specified time is conveniently recorded as a calculated actual value, and a steam supply rate is assigned to this value. The latter is then immediately adjusted by keeping it constant, increasing, or reducing it until the final temperature is reached. This allows the desired milk foam to be produced automatically. It is advantageous to determine the temperature difference between at least two points in time, with these points being determined after a specific period of time, such as 5 and 7 seconds, after the start of the steam supply. These points in time are chosen to ensure efficient production and, consequently, high-quality milk foam.

[0012] The invention provides that the steam supply output is determined after calculating the actual value using a look-up table in which the possible temperature differences are recorded in stages. By assigning the specified outputs to these, the steam supply is controlled accordingly. This enables a very precise adjustment of the output, regardless of whether a smaller cup, a pitcher, or a pot is used as the container.

[0013] The device according to the invention comprises at least one steam device, preferably designed as a steam lance, with a steam and an air supply line, a boiler for the hot steam generation with the steam line, at least one temperature probe immersible in the milk to be heated, a control and evaluation unit for the automated milk foam production and an operating panel for its control and the selection of the beverage.

[0014] The invention and further advantages thereof are explained in more detail below using exemplary embodiments with reference to the drawing. Fig. 1 shows a hydraulic diagram of the device for carrying out the method according to the invention; and

[0015] Fig. 2 is a diagram of the temperature rise of the milk as a function of time as the milk is heated by the device according to Fig. 1.

[0016] Fig. 1 shows a diagram of a device 10 for heating milk, and in particular for producing milk foam, in a container 12 containing the milk 13, which container can be placed on a support surface 19. Hot steam, for example from a boiler with a supply line 14, is fed via a steam line 16, and air is fed through an air supply line 17 through a steam device immersed in the milk 13 in the container 12. Furthermore, a temperature probe 18 is arranged on the front of the steam device, by means of which the temperature of the milk 13 in the container 12 can be continuously measured.

[0017] This device 10 can be integrated into a milk frother unit or preferably into a coffee machine which is not designed as a fully automatic device, but in which, for example, a piston receiving the coffee powder could be provided for producing the coffee, so that the operator could dispense the coffee into a cup through the manually attached piston during the automated milk froth production in one container and then pour milk froth onto it.

[0018] The steam device is a steam lance 11 which can be immersed in the container 12 and which has an outlet 11' on the front for the hot steam and the air. This steam lance 11 is advantageously pivotally mounted and can be pivoted into and out of the container 12 accordingly, which is not illustrated in more detail. The steam line 16 contains a valve 21 and a proportional valve 22 or the like which adjusts the output of the hot steam. The air supply line 17 comprises an intake opening 23, a compressor 27, and a subsequent valve 24, with the two valves 21, 24 serving to open and close the respective lines 16, 17. In addition, one valve 15 downstream of the proportional valve 22 has an outlet for the water from the boiler for cleaning purposes.

[0019] Cappuccinos, latte macchiatos, or other well-known milk-based beverages can be prepared. Cups, glasses, or larger vessels such as jugs, pitchers, or the like are suitable as containers 12. After the milk foam has been created, the milk, with the foam on top, can be dispensed from the jug into cups. Milk alone or a flavored mixed drink made from milk and a flavoring agent such as chocolate, vanilla, caramel, nut, and / or other substances, or a fruit syrup made from raspberries, bananas, etc., can be used. This can be animal or plant-based milk from coconuts, soy, etc., or milk made from a mixture of powdered milk and water.

[0020] In the boiler or similar, steam is generated at an operating pressure of advantageously approximately 2 bar, which flows through the steam line 16 into the steam lance 11 and from its outlet 1T into the milk 13. The air supply line 17 leads into the steam line 16, with the sucked-in air being pumped into the steam line 16 by a compressed air source via the compressor 27. The air could also be fed directly into the container 12. The valves 21, 24 of this proportional valve 22, which adjusts the output of the hot steam and serves as an adjusting element, the compressor 27, and the temperature probe 18 are each electrically connected to a control and evaluation unit 25 via a control line 26, 28, 29, 31, 33. In principle, the valves could alternatively communicate with the control and evaluation unit via a wireless connection.In addition, an operating panel 32 is indicated, which is also electrically connected to the control and evaluation unit 25 by a cable structure 33.

[0021] Different foam qualities or types can be produced, which can be selected by the user on the control panel 32. This can be normal, classic, compact cappuccino milk foam, or other variations. This allows different consistencies of milk foam to be produced, which are particularly desirable when using the device in a coffee machine. The air supply is adjusted accordingly depending on the formation of the milk foam.

[0022] As can be seen in Fig. 2, according to the invention, when the heating of the milk 13 filled in the container 12 starts, steam is supplied to the milk at a predetermined rate. During milk foam production, the air supply is switched on at the beginning or after a specific time t1. After the steam supply starts at time t0, a temperature difference ΔT of the measured milk temperatures T1, T2 at these times is determined between a predetermined first and a second fixed time t1, t2, wherein based on the temperature difference ΔT at least the hot steam is supplied either at the same or with a changed rate and this steam supply is switched off before or when the final temperature T3 of the milk 13 is reached.

[0023] Alternatively or additionally, a temperature gradient can be determined based on the specified times t1, t2 and the milk temperatures T1, T2 measured at these times, by means of which at least the hot steam is supplied either with the same or with a changed output and the steam supply is switched off before or when the final temperature T3 of the milk 13 is reached.

[0024] It is very advantageous to supply the hot steam at a reduced, preferably constant, rate to the milk 13 in the container 12 at the start of heating. This prevents the milk from overheating and splashing out of the cup, for example when a smaller cup is used as the container. With such a small cup, the milk 13 will already have a relatively high temperature T1 after the first time t1, and the temperature difference ΔT will be correspondingly high, so that the hot steam rate is reduced or, like the air supply, stopped shortly thereafter, as soon as the final temperature T3 is reached. This shutdown can also occur beforehand, because the inertia of the temperature measurement can lead to delays between the time of measurement and the recording of the measured temperature. This can also be compensated for by correcting the measured temperature. Fig.Figure 2 shows a diagram of the temperature curve when milk is heated in a container, with time t along the abscissa and temperature T along the ordinate. Heating begins at t0 after the container has been placed down and the steam lance has been swung into it, and shortly thereafter the air supply t1 is switched on. For the temperature difference ΔT, the absolute value in Kelvin is measured or determined between the two measuring points at times t1 and t2. The times are set, for example, after 5 and after 7 seconds after the start of the steam supply t0. These can of course be set differently. They are based on the entire heating time and, if possible, set as early as possible after the start t0 so that the milk is heated efficiently, not too quickly, and the foam can be formed as specified.Before starting, a milk temperature TO in the cooling range of 5 to 8°C is assumed. After the first time t1, this has risen to approximately 30 to 40°C, and its final temperature is a maximum of 65°C. When using, for example, a jug as container 12 with a fill level of more than half, the total time is preferably 30 to 60 seconds.

[0025] It is also evident in Fig. 2 that the quantity of steam supplied has been reduced after the determined temperature difference ΔT compared to the initial quantity so that the milk is not heated up too quickly, which would lead to a suboptimal milk foam.

[0026] The temperature difference ΔT at which the measured milk temperatures

[0027] T1 and T2 are subtracted after the first time t1 and after the second specified time t2, is registered as a calculated actual value and assigned to this a quantity of steam supply and the latter is immediately adjusted as follows:

[0028] > At a predetermined actual value, the quantity of steam supply is maintained so that the milk 13 is heated with the same temperature increase.

[0029] > If the actual value is relatively small, the steam supply rate is preferably increased until the final temperature T3 is reached.

[0030] > On the other hand, if the actual value is high, the steam supply rate is preferably reduced until the final temperature T3 is reached.

[0031] The air supply is preferably switched on after heating has started with the steam supply. This can happen after one second, for example. However, it could also be switched on at the same time or even before the steam supply. This also depends on whether the air is sucked in by the hot steam or whether it is supplied by a compressor pump with a similarly predetermined output. The various foam qualities or consistencies are determined by the specified duration of the air supply and / or steam supply or by the mixing ratio of the steam quantity to the air quantity. The air supply can also be dynamically determined in terms of quantity and / or duration or the time of pause using a look-up table, a specific calculation, or otherwise.By means of the method, this can be specifically determined within the scope of the invention, so that regardless of the amount of milk in a jug or a cup, a milk foam can always be produced as desired.

[0032] The quantity of steam supplied is advantageously increased or reduced differently depending on the extent of the difference when the actual value is exceeded or undershot.

[0033] The steam supply output can be determined using a conventional look-up table, in which the possible temperature differences (ΔT) are graded. By assigning the specified steam output, the proportional valve 22 in the steam line 16 is controlled accordingly. An example look-up table is shown below:

[0034] In the alternative determination of the quantity of hot steam through the temperature gradient, this can be done, for example, by creating a rotatable vector as a visualization, which, depending on the temperature change from the first to the second specified time t1, t2, can assume a corresponding angle of up to +90º compared to a horizontal orientation with an unchanged temperature, for example, through which it is determined, depending on the determined angular position of the vector, whether the steam supply should take place with the same or with a changed quantity of output and whether the air supply should be maintained or stopped.

[0035] As mentioned, the angular position of the vector is determined by the temperature change from the first to the second specified time t1, t2. This can be easily recorded using software in the control and evaluation unit 25. A well-known look-up table is also suitable for this purpose. This look-up table is divided according to the determined temperature gradient and can trigger the control accordingly by assigning it to the output of the hot steam. An example look-up table is shown below:

[0036] This temperature gradient can also be visualized instead of a vector on a display designed as a bar or similar. In principle, a continuous assignment of the temperature gradient to the output could also be made. When producing a specific milk foam, for example a classic foam for a cappuccino, the operator can first manually swing the steam lance 11 into the container 12 containing the milk 13 and place the container on the storage surface 19. The steam lance 11 is designed such that its front outlet 11' is a short distance from the storage surface 19 for the container 12, advantageously a few millimeters, so that this outlet 11 is always immersed in the milk 13 in the container 12, even if only a small amount of milk is filled in.

[0037] The operator can then select the desired cappuccino by pressing a button on the control panel 32, which is typically equipped with a touchscreen with various indicated buttons 34. Corresponding signals are then sent from the control panel 32 via the line structure 33 to the control and evaluation unit 25, which, via line 29, controls the proportional valve 22 to open the steam line 16, so that hot steam is directed at a specific flow rate to the outlet 11* of the steam lance 11 and into the milk 13. In addition, the control and evaluation unit 25 opens the valve 24, preferably immediately after the proportional valve 22, and air is fed into the hot steam through the air supply line 17 by the controlled compressor 27.

[0038] This output is set to the same level at every start-up so that the same heat output is always delivered up to the selected times, ensuring adequate conditions at those times. At start-up, the control and evaluation unit 25 measures the time t and the temperatures in the milk 13 via the temperature probe 18 at the front of the steam lance 11. As soon as the first time t1 is reached, for example, after 5 seconds, the temperature T1 is recorded, as is the temperature T2 at the second time t2, for example, after 7 seconds.Immediately afterwards, depending on the application, either the temperature difference ΔT is calculated by subtraction or the temperature gradient is determined and the steam supply rate is immediately left the same, reduced or increased using the look-up table, with the assigned magnitude of the rate. For example, if the temperature difference ΔT + 10ºC has been calculated, the rate is set to 40%, or with a temperature gradient at a vector position of + 45º, the rate is set to 50%. As soon as the final temperature T3, for example 65ºC, is reached, the proportional valve 22 is closed. The valve 24 for the air supply is preferably closed before the proportional valve 22. The time at which the air supply is switched off between the second time t2 and the final temperature T3 can also be programmed and may depend on the foam type selected before starting.

[0039] The control of the device 10 explained above is carried out by a software program in the control and evaluation unit 25 or in a CPU or similar in a coffee machine.

[0040] The invention is sufficiently illustrated by the exemplary embodiments explained above. However, it could of course be explained by other variants. Instead of a steam wand inserted from above, as shown, a steam wand could be provided in the bottom of the container, with steam and air blown in from below. Advantageously, the container would be tightly placed from above onto a cone-shaped steam wand. After heating and, if necessary, frothing the milk inside, the container could be lifted off using a closure at the lower opening of the container for the steam wand, and the frothed milk could be poured into cups.

[0041] In principle, a third time point with a second temperature difference and / or a further temperature gradient could be provided between this and the first or second time point. Again, based on the temperature difference and / or the temperature gradient, at least the steam could be supplied again, either at the same or at a further modified rate, and the air could be continued or stopped, and this steam supply could be switched off when the final milk temperature is reached.

[0042] After the milk has started heating up, the steam supply in the container could be controlled at a varying output. For example, the amount of steam used could be reduced from full output at the beginning and then increased before the first time point is reached. However, it is important to ensure that the total output is set the same each time up to the second time point, and that if this total output were to be changed, the temperature difference and / or the temperature gradient would also have to be adjusted. Temperature measurement is advantageously carried out continuously and / or intermittently. In principle, it could also be carried out only at the time points and towards the end when the final temperature is reached. The temperature probe is very advantageously attached to the steam lance. In principle, however, it could be placed inside the container, for example if the steam device is located in the base of the container.

[0043] An additional sensor could be arranged on the steam lance, which could determine the milk consistency and forward it to the control and evaluation unit, so that an additional parameter would be available at least for setting the control of the quantity of hot steam and the air supply.

[0044] Likewise, the arrangement and number of valves in the system can, of course, be designed differently than shown, depending on requirements. For example, instead of a single proportional valve, several valves could be provided, each with a specific flow rate, with the appropriate valve activated depending on the temperature gradient.

Claims

PATENT CLAIMS 1. A method for producing, in particular, milk foam in a container (12) containing the milk, wherein hot steam is supplied by at least one steam device immersed in the milk (13) in the container (12) with a controllable output and with air or a gas, wherein the milk temperature is measured and evaluated during heating by at least one temperature probe (18) within the container (12), characterized in that at the start of heating of the milk (13) filled in the container (12), steam is supplied with a predetermined output, and that for the milk foam production, the air supply is preferably switched on at the beginning, wherein after the start of the steam supply, at least between a predetermined first and a second fixed time (t1, t2) a temperature difference (ΔT) of the measured milk temperatures (T1,T2) at these times and / or that a temperature gradient of the milk (13) is determined, wherein on the basis of the temperature difference (ΔT) and / or the temperature gradient at least the hot steam is supplied either with the same or with a changed output and is switched off before or when the final temperature (T3) of the milk (13) is reached.

2. Method according to claim 1, characterized in that the hot steam is supplied at a reduced, preferably constant, quantity into the milk (13) filled in the container (12) at the start of heating.

3. Method according to claim 1 or 2, characterized in that the air or gas is switched on and supplied in a controlled manner with the steam supply after the start of heating.

4. Method according to one of claims 1 to 3, characterized in that the temperature difference (ΔT) at which the first time (t1) is subtracted from the second fixed time (t2) is registered as a calculated actual value and a quantity of steam supply is assigned to this and the latter is immediately adjusted as follows: > at a predetermined actual value, the quantity of steam supply is maintained so that the milk (13) is heated with the same temperature increase; > if the actual value is relatively small, the steam supply rate is preferably increased until the final temperature (T3) is reached; > If the actual value is high, the quantity of steam supplied is preferably reduced until the final temperature (T3) is reached.

5. Method according to claim 4, characterized in that the quantity of steam supplied when the value is exceeded or undershot The actual value is increased or reduced differently depending on the extent of the difference.

6. Method according to claim 5, characterized in that the determination of the quantity of steam supply is carried out after the calculation of the actual value with the aid of a look-up table in which the possible temperature differences (ΔT) are registered in stages, and by assigning the predetermined quantities to these, the steam supply is controlled accordingly.

7. Method according to one of claims 1 to 6, characterized in that the temperature difference (ΔT) of the measured milk temperatures (T1, T2) is determined at these times, which are determined after a certain period of time, such as after 5 and after 7 seconds after the start of the steam supply.

8. Method according to one of claims 1 to 5, characterized in that the temperature gradient is formed by a vector or the like which, depending on the temperature change from the first to the second time (t1, t2), for example, has a corresponding angle of rotation relative to a horizontal orientation at an unchanged temperature, by which angle of rotation it is determined, depending on the determined angle of rotation position of the vector, whether the steam supply is to be carried out with the same or with a changed quantity of output. tion should take place and whether the air supply should be maintained or stopped.

9. Method according to one of claims 1 to 8, characterized in that different foam qualities or consistencies of the milk foam to be produced can be selected, wherein the different foam qualities or consistencies are each determined, for example, by the fixed duration of the air supply and / or the steam supply or by the mixing ratio of the amount of steam to the amount of air.

10. Method according to one of claims 1 to 9, characterized in that both animal milk and vegetable milk from coconuts, soy or from a milk mixture produced from milk powder and water can be used as the milk.

11. Device, preferably a coffee machine, for carrying out the method according to one of claims 1 to 10, characterized in that the device (10) comprises at least one steam device, preferably designed as a steam lance (11), with a steam and an air supply line (16, 17), a boiler or the like for generating hot steam with the steam line (16), at least one temperature probe (18) that can be immersed in the milk to be heated, a control and evaluation unit (25) for the automated milk foam production and an operating panel (32) with a display or the like for its control and the selection of the beverage.

12. Device according to claim 11, characterized in that the control and evaluation unit (25) is electrically connected to the at least one temperature probe (18) immersed in the milk (13) to be heated in the container (12) and to at least one adjusting element for the quantity of steam supply and a valve (24) for air supply, wherein the control and evaluation unit (25) is controllable by a software program.

13. Device according to claim 11 or 12, characterized in that the steam device designed as a steam lance (11), which can be manually immersed in the container (12), is provided with the steam and air supply line (16, 17) and at the front with an outlet (11'), wherein the outlet (11') can be positioned at a small distance of a few millimeters from a storage surface (19) for the container (12) in order to be safely immersed in the milk (13) emptied in the container (12).

14. Device according to one of claims 11 to 13, characterized in that the air supply line (17) leads into the steam line (16) and the air can be sucked in from the hot steam by means of a venturi, or that a compressed air source, preferably the compressor (27), is provided, through which the air can be conveyed into the steam and then into the milk.

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