Device for frothing milk and coffee machine comprising such device

Abstract

Apparatus (1) for frothing milk, comprising: a milk container (2); a manifold (6) for suctioning air and milk by Venturi effect from a first line (5) for suctioning air from an external atmospheric environment and a second line (7) for suctioning milk from said container (2), respectively; a line (8) for introducing steam into the manifold (6) to trigger the Venturi effect; means for adjusting a minimum air passage port along the first air extraction line (5); and means for adjusting a minimum milk passage port along the second milk extraction line (7).

Description

[0001] The invention relates to a device for frothing milk and to a coffee machine comprising such a device.

[0002] Devices for frothing milk, which can be associated with coffee machines, are already known.

[0003] Some types of known devices comprise a milk container provided with a cover incorporating a Venturi effect mixing chamber in which air and milk collected from the container are mixed by the Venturi effect triggered by a flow of steam.

[0004] The passage of air into the mixing chamber may be provided with a progressively opening valve, by operating which the degree of frothing of the milk may be modified.

[0005] One of the limitations of known devices of these types is the limited ability to diversify the range of frothed milk that can be produced.

[0006] In particular, with known devices of these types it is not possible to produce cold frothed milk, since the steam flow used to trigger the Venturi effect and the extraction of milk heats the milk that is sucked into the mixing chamber.

[0007] Such known apparatus for frothing milk may have other disadvantages, including the complexity of accessing internal components for inspection and cleaning.

[0008] This problem is particularly acute when considering that any milk residue that solidifies inside the device may cause blockage of the milk flow through the ports and thus affect the efficiency of the device.

[0009] Last but not least, milk residues solidified inside the equipment may also negatively affect the organoleptic properties of the product and generate unpleasant malodors.

[0010] For this reason, such devices may be provided for the injection of liquid detergent for washing the internal parts, which obviously have to be rinsed carefully.

[0011] EP 1 115 317 B1 shows a device for frothing milk comprising a tap for regulating the flow of milk sucked in by the Venturi effect.

[0012] The disadvantage of this device is that it does not provide flexibility in use when used to dispense beverages at a wide range of temperatures and foaming levels.

[0013] The technical task of the present invention is therefore to realize a device for frothing milk and a coffee machine which eliminate the above-mentioned technical drawbacks of the prior art.

[0014] Within the scope of this technical task, an object of the present invention is to realize a device for frothing milk and a coffee machine comprising such a device which allow to produce directly in a cup a wide variety of products based on hot or cold frothed milk with various degrees of frothing.

[0015] Another object of the present invention is to fully automate the function of producing a wide variety of milk-containing products that can be selected by the user.

[0016] Another object of the invention is to achieve a device for frothing milk that is easy to inspect and clean.

[0017] Another object of the invention is to fully automate also the precision cleaning function of the device which can be selected by the user.

[0018] Another object of the invention is to provide a very safe device for frothing milk.

[0019] The technical task according to the invention and these and other objects are achieved by realizing a device for frothing milk, characterized in that it comprises: a milk container; a manifold for sucking air and milk respectively from a first line for extracting air from the external atmospheric environment and a second line for extracting milk from said container by means of the Venturi effect, the first line for extracting air from the external atmospheric environment and the second line for extracting milk from said container, the second line comprising a first milk extraction duct and a second milk extraction duct; a line for letting steam enter the manifold to trigger the Venturi effect; means for adjusting the minimum air passage port along said first air extraction line; and means for adjusting the minimum milk passage port along said second milk extraction line, the means comprising valve means for cutting off said second milk extraction duct.

[0020] In a preferred embodiment of the present invention, the device for adjusting the minimum air passage port along the first air extraction line is at least switchable between a first switching state corresponding to the first minimum air passage port and a second switching state corresponding to the second minimum air passage port, the second minimum air passage port being larger than the first minimum air passage port, and the device for adjusting the minimum milk passage port along the second milk extraction line is at least switchable between a first switching state corresponding to the first minimum milk passage port and a second switching state corresponding to the second minimum milk passage port, the second minimum milk passage port being larger than the first minimum milk passage port.

[0021] In a preferred embodiment of the present invention, the first air extraction line comprises a first air extraction duct and a second air extraction duct, and the device for adjusting the minimum air through port comprises a first valve device for cutting off the first air extraction duct and a second valve device for cutting off the second air extraction duct.

[0022] In a preferred embodiment of the present invention, the first valve means for cutting off the first air extraction duct comprises a first solenoid valve, and the second valve means for cutting off the second air extraction duct comprises a second solenoid valve.

[0023] In a preferred embodiment of the present invention, the first air extraction duct and the second air extraction duct are connected.

[0024] In a preferred embodiment of the invention, said valve means for shutting off said second milk extraction conduit comprises a manual valve.

[0025] In a preferred embodiment of the present invention, the manual valve comprises a gate rod which can self-rotate in a valve body intersecting the second milk extraction conduit, the rod having a channel which can be aligned with the second milk extraction conduit for opening the second milk extraction conduit.

[0026] In a preferred embodiment of the present invention, the first milk extraction conduit and the second milk extraction conduit are in communication.

[0027] In a preferred embodiment of the invention, said manifold is integrated into a lid for closing said milk container.

[0028] In a preferred embodiment of the invention, the device for frothing milk comprises an electronic controller having a program for dispensing a beverage, the program providing a selection for adjusting the state of the means for minimal air and milk passage through the port.

[0029] In a preferred embodiment of the invention, the electronic controller has a cleaning program which provides for the selection of the state of the means for adjusting a minimum air through port which is wide enough to prevent milk from being sucked back towards the manifold.

[0030] The invention also discloses a coffee machine comprising such a milk frothing device.

[0031] In a preferred embodiment of the invention, the device has removable connection means between a wall of the cover and a wall of the coffee machine.

[0032] Other characteristics and advantages of the invention will become more apparent from the description of a preferred but not exclusive embodiment of a device for frothing milk according to the invention and of a machine comprising said device, illustrated by way of non-limiting example in the accompanying drawings, in which:

[0033] Figure 1 shows a front view of a coffee machine including a device for frothing milk;

[0034] Figure 2 Shows Figure 1 A front view of a coffee machine with a milk container removed from the coffee machine;

[0035] Figure 3a Shows Figure 1 side elevation view in vertical section of a coffee machine of , wherein parts of the device for frothing milk are highlighted, wherein a milk container provided with a cover is removed from a front wall of the coffee machine;

[0036] Figure 3b Shows Figure 1 side elevation view in vertical section of a coffee machine of , wherein parts of the device for frothing milk are highlighted, wherein a milk container provided with a cover is connected to the front wall of the coffee machine;

[0037] Figure 4 and Figure 5 an axonometric view showing a milk container with a lid provided with a device for frothing milk;

[0038] Figure 6a , Figure 6b and Figure 6c The container provided with a lid is shown in an exploded view;

[0039] Figure 7a and Figure 7b Shows Figure 6b a vertical section of a milk container provided with a cover of a device for frothing milk, wherein the means for adjusting the minimum milk passage port are shown in a first state and a second state, respectively; and

[0040] Figure 8 Shows relative to Figure 7a and Figure 7b Vertical section through the milk container provided with a lid of the device for frothing milk rotated through 90°.

[0041] With reference to the above-mentioned figures, there is shown a device for frothing milk, indicated as a whole with the reference numeral 1 .

[0042] The device 1 comprises a milk container 2 provided with a closure lid 3 and an external milk dispenser 25 .

[0043] The closure cap 3 is preferably configured for closing the milk container 2 .

[0044] The lid 3 is removable from the container 2 in order to refill the container 2 with fresh milk once the container 2 is empty.

[0045] As we will see, the cover 2 has a hollow structure to accommodate some of the components of the device 1 therein.

[0046] The device 1 comprises a manifold 6 for aspirating air and milk by venturi effect, the manifold preferably being housed in the lid 2 and connected at the outlet to an external milk dispenser 25 .

[0047] The device 1 comprises a first line 5 for extracting air from the external atmosphere and a second line 7 for extracting milk from the container 2 .

[0048] The air extraction line 5 and the milk extraction line 7 are in communication with a manifold 6 which can then extract air and milk respectively from these lines by means of the Venturi effect.

[0049] The apparatus 1 provides a line 8 for steam to enter the manifold 6 to trigger the venturi effect.

[0050] The device 1 also provides means for adjusting the minimum air passage port along the first air extraction line 5 .

[0051] The device for adjusting the minimum air passage port along the first air extraction line 5 can be switched between at least a first switching state and a second switching state, wherein the first switching state corresponds to a first minimum air passage port along the first air extraction line 5 and the second switching state corresponds to a second minimum air passage port along the first air extraction line 5, wherein the second minimum air passage port is larger than the first minimum air passage port.

[0052] The device 1 also provides means for adjusting the smallest milk passage port along the second milk extraction line 7 .

[0053] The device for adjusting the minimum milk passage port along the second milk extraction line 7 can be switched between at least a first switching state corresponding to a first minimum milk passage port and a second switching state corresponding to a second minimum milk passage port, the second minimum milk passage port being larger than the first minimum milk passage port.

[0054] The first air extraction line 5 includes a first air extraction conduit 5a and a second air extraction conduit 5b.

[0055] The means for regulating the minimum air passage port comprise first valve means 9 for cutting off the first air extraction duct 5a and second valve means 10 for cutting off the second air extraction duct 5b.

[0056] The first valve device 9 for shutting off the first air extraction duct 5a comprises a first solenoid valve 9a.

[0057] The second valve device 10 for shutting off the second air extraction duct 5b includes a second solenoid valve 10a.

[0058] The first minimum air through-port along the first air extraction line 5 may correspond to opening only the first air extraction duct 5a by the first solenoid valve 9a.

[0059] In practice, in this case, the first smallest air passage port along the first air extraction line 5 corresponds to the smallest air passage port of the first air extraction duct 5a.

[0060] Preferably, the smallest air passing port of the first air extraction duct 5a is exactly the port at which the first solenoid valve 9a intervenes by closing and opening.

[0061] The second smallest air through-port along the first air extraction line 5 may correspond to the second air extraction duct 5b being opened only by the second solenoid valve 10a.

[0062] In practice, in this case, the second smallest air passage port along the first air extraction line 5 corresponds to the smallest air passage port of the second air extraction duct 5 b.

[0063] Therefore, the smallest air passage port of the second air extraction duct 5 b is larger than the smallest air passage port of the first air extraction duct 5 a .

[0064] Preferably, the smallest air passing port of the second air extraction duct 5b is exactly the port at which the second solenoid valve 10a intervenes by closing and opening.

[0065] The diameter of the smallest air passage port of the first air extraction duct 5a is between 0.05 mm and 0.20 mm, and the diameter of the smallest air passage port of the second air extraction duct 5b is between 0.20 mm and 1.00 mm.

[0066] The air passage ports are calibrated to obtain an intake air flow rate of between 1.3 cc / s and 4 cc / s when the first air extraction duct 5a is open and between 5 cc / s and 9 cc / s when the second air extraction duct 5b is open, by triggering of the Venturi effect.

[0067] The first air extraction duct 5 a and the second air extraction duct 5 b are preferably in communication at a branching node 5 c of the first air extraction line 5 .

[0068] Downstream (in the air flow direction) of the branching node 5c, the single duct 5d of the first air extraction line 5 supplying the manifold 6 has, as described above, a minimum air passage port which is not smaller than that of the second air duct 5b.

[0069] The second milk extraction line 7 comprises a first milk extraction conduit 7a and a second milk extraction conduit 7b.

[0070] The means for adjusting the minimum milk passage port comprises valve means 11 for cutting off the second milk extraction duct 7b.

[0071] The valve means 11 for cutting off the second milk extraction conduit 7b comprises a manual valve 11a.

[0072] The manual valve 11a includes a knob 11e and a gate rod 11b which is self-rotatable in a valve body 11c intersecting the second milk extraction conduit 7b.

[0073] The rod lib has channels 11f, 11d, 11g inside which can be aligned with the second milk extraction duct 7b to open a milk passage through the second milk extraction duct 7b.

[0074] More precisely, the passage inside the rod lib comprises an internal axial chamber 11f of the rod lib having an axial inlet path 11g and a radial outlet path 11d.

[0075] The axial inlet path 11g is always open, whereas the radial outlet channel 11d can be opened or closed depending on the angular position of the rod 11b.

[0076] The diameter of the outlet path 11d is preferably between 3 mm and 8 mm, the inlet path 11g and the axial chamber 11f having a larger diameter.

[0077] The diameter of the smallest through port of the first milk extraction duct 7a is between 0.5 mm and 2 mm, and the diameter of the smallest through port of the second milk extraction duct 7b is between 3 mm and 10 mm.

[0078] The milk passage port is calibrated to obtain a milk intake flow rate of between 3 and 6 gr / s when only the first milk extraction duct 7a is open, and between 10 and 15 gr / s when the second milk extraction duct 7b is also open, by triggering of the Venturi effect.

[0079] The stem 11 b may be made of a rigid material such as plastic or metal and the valve body 11 c may be made of rubber to ensure a mutual fluid-tight form and force connection.

[0080] The first milk extraction conduit 7a and the second milk extraction conduit 7b are in communication.

[0081] The first smallest milk through port along the second milk extraction line 7 corresponds to only the first milk extraction duct 7a being open.

[0082] In practice, in this case the first smallest milk through-port along the second milk extraction line 7 corresponds to the smallest milk through-port of the first milk duct 7a.

[0083] The second smallest milk through port along the second milk extraction line 7 corresponds to the second milk extraction duct 7 b also being opened by the manual valve 11 .

[0084] In practice, the second smallest milk through-port along the second milk extraction line 7 corresponds in this case to the sum of the smallest milk through-ports of the first milk duct 7a and the second milk duct 7b.

[0085] However, the smallest milk passage port of the second milk extraction duct 7b is larger than the smallest milk passage port of the first milk extraction duct 7a.

[0086] The first milk extraction conduit 7a and the second milk extraction conduit 7b are preferably connected at a branching node of the second milk extraction line 7 .

[0087] Upstream of the branching node (in milk flow direction), the single duct 7c of the first milk extraction line 7 extending towards the bottom of the milk container 2 has a smallest milk through port which is not smaller than the sum of the smallest milk through ports of the first and second milk extraction ducts 7a, 7b.

[0088] In this case, the first milk extraction conduit 7a and the second milk extraction conduit 7b join before entering the manifold 6 .

[0089] Downstream of the junction (in milk flow direction), the single duct 7d of the first milk extraction line 7 leading into the manifold 6 has a smallest milk through port which is not smaller than the sum of the smallest milk through ports of the first and second milk extraction ducts 7a, 7b.

[0090] The steam inlet line 8 in the manifold 6 for triggering the venturi effect comprises a steam source 12 , in particular a boiler 13 .

[0091] The device 1 finally comprises an electronic controller 14 to which the first solenoid valve 9a, the second solenoid valve 10a and the steam boiler 13 are connected.

[0092] The electronic controller 14 is specifically in the form of a PCB board.

[0093] The device 1 may be incorporated into a coffee machine 15 .

[0094] In this case, the electronic controller 14 may be the same as that conventionally provided in a coffee machine 15 .

[0095] The coffee machine 15 generally has a hydraulic circuit (not shown) which cascades together a water source, a water feed pump, a boiler and an infuser.

[0096] The hydraulic circuit of the coffee machine 15 also comprises a steam production line which may employ the above-mentioned boiler 13 or a dedicated boiler for this purpose.

[0097] The water source can be a tank integrated into the coffee machine or a connection to the water mains.

[0098] The infuser is connected to an external coffee dispenser 16 which is supported by a front wall 17 of the coffee machine 15 .

[0099] The external coffee dispenser 16 can dispense the beverage directly into a cup 18 underneath, which is positioned on a front flat surface 19 of the coffee machine 15 for resting the cup.

[0100] The device 1 mentioned may share some resources with the coffee machine 15 , including the electronic controller 14 .

[0101] For example, as mentioned above, the boiler 13 may also be a boiler usually provided in the hydraulic circuit of a coffee machine for generating steam.

[0102] The device 1 has removable connection means between the wall 20 of the cover 3 and a wall of the coffee machine 15, in particular the front wall 17 of the coffee machine 15.

[0103] The removable connecting device comprises a first fitting 21a, 21b and a second fitting 22a, 22b, the first fitting being used for connection between the section 5e of the air extraction line 5 integrated into the cover 3 and the sections 5a, 5b, 5c, 5d, 9a, 10a integrated into the coffee machine 15, and the second fitting being used for connection between the section 8c of the steam inlet line 8 integrated into the cover 3 and the sections 8a, 8b, 13 integrated into the coffee machine 15.

[0104] The section of air extraction line 5 within the coffee machine 15 comprises two ducts 5a, 5b and associated solenoid valves 9a, 10a and a single duct 5d downstream of the branch 5c.

[0105] The section of the steam inlet line 8 which is also within the coffee machine 15 comprises the boiler 13 , the delivery duct 8 a of the boiler 13 and the supply duct 8 b of the boiler 13 .

[0106] The first fitting 21 a and the second fitting 22 a are preferably made of a block 23 which is removably engaged in a housing 24 of the wall 20 of the cover 3 .

[0107] In practice, between the two walls 17, 20, which are conveniently vertical and flat, there is an interface area where the connection between the cover 3 and the coffee machine 15, necessary for the operation of the device 1, is located.

[0108] The fittings 21a, 21b and 22a, 22b, respectively, may be joined by a horizontal coupling.

[0109] In the position in which the fittings 21 a , 21 b and 22 a , 22 b , respectively, are coupled, the container 2 rests on the flat surface 19 .

[0110] The flat surface 19 can then serve as a guide for coupling the fittings 21a, 21b and 22a, 22b, respectively.

[0111] The operation of the device 1 according to the invention is apparent from what has been described and illustrated and, in particular, is substantially as follows.

[0112] The user can select the drink manually through a special user interface provided by the device 1 and preferably integrated in the coffee machine 15 , in particular in a dashboard usually provided by the coffee machine 15 .

[0113] If desired, the selection of a beverage on the user interface may be accompanied by the switching of the manual valve 11 .

[0114] In case of selecting to dispense frothed cold milk via the user interface, the user must ensure that the manual valve is in the open state, or if not, to put it in the open state; the electronic controller 14 executes a dispensing program which provides for deactivation of the solenoid valve 9a corresponding to the closing of the first air extraction duct 5a, activation of the solenoid valve 10a corresponding to the opening of the second air extraction duct 5b, placing the manual valve 11 in a position opening the second milk extraction duct 7b, and activating the steam source 12.

[0115] The steam flow triggers a Venturi effect, by which milk and air are drawn into the manifold 6 .

[0116] As both milk extraction ducts 7a and 7b are open, the steam flow calls up a high flow of milk by the Venturi effect, supplying thermal energy to the milk which does not lead to a significant increase in the temperature of the milk dispensed in the cup.

[0117] The same steam flow invokes, through the Venturi effect, a flow of air which helps to froth the milk.

[0118] In case of selecting to dispense cold non-foamed milk via the user interface, the user must ensure that the manual valve is in the open state, if not it must be opened; the electronic controller 14 executes a dispensing program which provides for deactivation of the solenoid valve 9a corresponding to the closing of the first air extraction duct 5a, deactivation of the solenoid valve 10a corresponding to the closing of the second air extraction duct 5b, placing the manual valve 11 in a position opening the second milk extraction duct 7b, and activating the steam source 12.

[0119] Unlike the previous case, the milk does not froth due to the absence of air flow.

[0120] In case of selecting to dispense frothed hot milk via the user interface, the user must ensure that the manual valve is in the closed state, if not, to bring it into the closed state; the electronic controller 14 executes a dispensing program which provides for the activation of the solenoid valve 9a corresponding to the opening of the first air extraction duct 5a, the deactivation of the solenoid valve 10a corresponding to the closing of the second air extraction duct 5b, the manual valve 11 being in a position closing the second milk extraction duct 7b, and the activation of the steam source 12.

[0121] The steam flow triggers a Venturi effect, by which milk and air are drawn into the manifold 6 .

[0122] Since only the first milk extraction duct 7a is open, the steam flow calls up a moderate milk flow by the Venturi effect, to which it provides thermal energy which causes a significant increase in the temperature of the milk dispensed in the cup.

[0123] The same steam flow invokes, through the Venturi effect, a flow of air which helps to froth the milk.

[0124] In case of selecting to dispense hot non-foamed milk via the user interface, the user must ensure that the manual valve is in the closed state, or if not, to put it in the closed state; the electronic controller 14 executes a dispensing program which provides for deactivating the solenoid valve 9a corresponding to the closing of the first air extraction duct 5a, deactivating the solenoid valve 10a corresponding to the closing of the second air extraction duct 5b, placing the manual valve 11 in a position closing the second milk extraction duct 7b, and activating the steam source 12.

[0125] The steam flow triggers the Venturi effect, by which the milk is sucked into the manifold 6 .

[0126] Since only the first milk extraction duct 7a is open, the steam flow calls up a moderate milk flow by the Venturi effect, to which it provides thermal energy which causes a significant increase in the temperature of the milk dispensed in the cup.

[0127] Since the air extraction line 5 is completely closed, the same steam flow cannot extract the air flow for frothing the milk by the Venturi effect.

[0128] Users can also select a cleaning function.

[0129] When the user selects the cleaning function, the electronic controller 14 executes a cleaning program which provides for the solenoid valve 9a to be activated corresponding to the opening of the first air extraction duct 5a, the solenoid valve 10a to be activated corresponding to the opening of the second air extraction duct 5b, the manual valve 11 to be in any position, and the steam source 12 to be activated preferably intermittently.

[0130] The steam flow triggers the Venturi effect, whereby only air is sucked into the manifold 6 , which due to the large through port opened along the air extraction line 5 prevents milk from being sucked from the container 2 .

[0131] The user interface may include a display, and each time the user selects a drink, the display will display a warning to remind the user to manually select the switching state of the manual valve 11 correctly.

[0132] Alternatively, the device 1 can provide a position sensor, for example a magnetic type position sensor, which identifies the angular position of the gate rod and thus identifies the switching state of the manual valve 11. If the current switching state is inconsistent with the user's choice of drink to be made, a warning can be automatically displayed on the user interface display to enable the user to change the switching state of the manual valve 11.

[0133] The device 1 has a very high flexibility of use.

[0134] Since the milk dispenser 25 can be oriented to dispense directly into the same cup 18 as the coffee dispenser 16 dispenses, the user can obtain a beverage through a simple manual selection operation of the user interface and the manual valve 11.

[0135] Many types of milk-based drinks can be selected and prepared.

[0136] Typically a drink is obtained which has a temperature which is not more than 20° C. higher than the temperature of the milk present in the milk container.

[0137] For example, when the temperature of the milk present in the milk container is between 3°C and 10°C, a cold drink not higher than 25°C can be obtained using a dispensing program which provides for the selection of the state of the manual valve 11 corresponding to the opening of the second milk extraction duct 7b.

[0138] It is also possible to obtain a hot drink which has a temperature which is typically up to 65° C. higher than the temperature of the milk present in the milk container.

[0139] For example, when the temperature of the milk present in the milk container is between 3 and 10°C, a hot beverage with a temperature typically between 50 and 75°C can be obtained with a dispensing program which provides for the selection of the state of the manual valve 11 corresponding to the closing of the second milk extraction duct 7b.

[0140] Simply by providing dispensing programs with different activation durations of the boiler 13, drinks with different ratios of milk and coffee can be obtained.

[0141] Simply by providing a dispensing program which leaves one or the other of the solenoid valves 9a, 10a open, a drink with or without foam can be obtained.

[0142] Finally, a variety of flavors of beverages can be obtained simply by providing a dispensing program for adding different additives or flavorings based on chocolate, vanilla, strawberry, etc.

[0143] Additives or flavorings in powder or liquid form may be added to the milk in container 2 .

[0144] The conceived device for frothing milk is susceptible to numerous modifications and variations, all falling within the scope of the inventive concept; moreover, all the details may be replaced by technically equivalent elements.

[0145] In practice, the materials used, as well as the dimensions, may be determined according to requirements and the state of the art.

Claims

1. A device (1) for frothing milk, characterized in that The device comprises: a milk container (2); a manifold (6) for sucking air and milk from a first line (5) and a second line (7) respectively by venturi effect, the first line being used to extract air from the external atmospheric environment, the second line being used to extract milk from the container (2), the second line comprising a first milk extraction conduit (7a) and a second milk extraction conduit (7b) being connected; a line (8) for allowing steam to enter the manifold (6) to trigger the venturi effect; means for adjusting the minimum air passage port along the first air extraction line (5); and means for adjusting the minimum milk passage port along the second milk extraction line (7), the means comprising valve means (11) for cutting off the second milk extraction conduit (7b).

2. The device (1) for frothing milk according to claim 1, characterized in that The device for adjusting the minimum air passage port along the first air extraction line (5) is at least switchable between a first switching state and a second switching state, the first switching state corresponding to a first minimum air passage port, the second switching state corresponding to a second minimum air passage port, the second minimum air passage port being larger than the first minimum air passage port, and the device for adjusting the minimum milk passage port along the second milk extraction line (7) is at least switchable between a first switching state and a second switching state, the first switching state corresponding to a first minimum milk passage port, the second switching state corresponding to a second minimum milk passage port, the second minimum milk passage port being larger than the first minimum milk passage port.

3. Device (1) for frothing milk according to any of the preceding claims, characterised in that The first air extraction line (5) comprises a first air extraction duct (5a) and a second air extraction duct (5b), and the means for adjusting the minimum air passage port comprises a first valve means (9) for cutting off the first air extraction duct (5a) and a second valve means (10) for cutting off the second air extraction duct (5b).

4. Device (1) for frothing milk according to the preceding claim, characterized in that The first valve device (9) for cutting off the first air extraction duct (5a) comprises a first solenoid valve (9a), and the second valve device (10) for cutting off the second air extraction duct (5b) comprises a second solenoid valve (10b).

5. Device (1) for frothing milk according to any one of claims 3 and 4, characterized in that The first air extraction duct (5a) and the second air extraction duct (5b) are in communication.

6. Device (1) for frothing milk according to any of the preceding claims, characterized in that The valve means (11) for cutting off the second milk extraction conduit (7b) comprises a manual valve (11a).

7. Device (1) for frothing milk according to the preceding claim, characterized in that The manual valve (11a) comprises a gate rod (11b) which can rotate in a valve body (11c) intersecting the second milk extraction conduit (7b), and the rod (11b) has a passage (11d) which can be aligned with the second milk extraction conduit (7b) for opening the second milk extraction conduit (7b).

8. Device (1) for frothing milk according to the preceding claim, characterized in that The first milk extraction conduit (7a) and the second milk extraction conduit (7b) are in communication.

9. Device (1) for frothing milk according to any of the preceding claims, characterized in that The manifold (6) is integrated into a lid (3) for closing the milk container (2).

10. Device (1) for frothing milk according to any one of claims 2 to 9, characterized in that The device comprises an electronic controller (14) having a program for dispensing a beverage, the program providing for selection of the state of the means for regulating the minimum air and milk passage ports.

11. Device (1) for frothing milk according to the preceding claim, characterised in that The electronic controller (14) has a cleaning program which provides for selection of the state of the means for adjusting the minimum air passage port, wherein the minimum air passage port is large enough to prevent milk from being sucked back into the manifold (6).

12. A coffee machine (15) comprising a device (1) for frothing milk according to any preceding claim.

13. Coffee machine according to the preceding claim, characterized in that The device (1) has removable connection means between a wall (20) of the cover (3) and a wall (17) of the coffee machine (15).

14. Coffee machine (15) according to the preceding claim, characterised in that The removable connection device comprises fittings (21a, 21b, 22a, 22b) for connection between sections of the air extraction line (5) respectively integrated in the cover (3) and in the coffee machine (15), and between sections of the steam inlet line (8) respectively integrated in the cover (3) and in the coffee machine (15).

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