Improved device for generating steam and pressurized air and method for controlling such a device

Abstract

The invention relates to a method for controlling a machine or device for generating and delivering steam and pressurized air for heating and emulsifying a food product (22), consisting in injecting steam and air into the product (22), the method comprising the steps of: - delivering the steam at a constant flow rate for a predefined duration as a function of the desired final temperature for the product (22), and - injecting the pressurized air into the product (22) so as to give the product (22) a desired consistency, characterized in that it consists of: - continuously operating an air pump (14) at its nominal speed in order to deliver the pressurized air, - injecting the steam into the product (22), - controlling the injection of the pressurized air into the product (22) for one or more cycles, each cycle comprising an injection activation period and a complementary injection deactivation period, the activation period being between 0% and 100% of the total duration of the cycle.

Description

[0001] DESCRIPTION

[0002] TITLE: IMPROVED DEVICE FOR PRODUCING STEAM AND AIR UNDER PRESSURE AND METHOD FOR CONTROLLING SUCH A DEVICE

[0003] Technical field

[0004] The invention relates to the general technical field of devices, systems or machines for heating a beverage and for generating foam from a product, for example milk. Machines for preparing hot beverages, for example cappuccino, hot chocolate or other coffee machines, are known, comprising such a device. The latter is commonly called a milk frother.

[0005] State of the art

[0006] Machines with a device for heating drinks or producing foam are well known. These machines are increasingly becoming automated in their operation.

[0007] However, such machines have a number of disadvantages. When used during peak periods when large numbers of customers need to be served, these machines are used by multiple operators, each of whom has a more or less personal way of preparing hot drinks. In addition, the products used, such as milk, are not always strictly identical, either in their consistency or in their starting temperature. It is therefore often difficult to guarantee consistency in the quality of the product or the hot drink obtained.

[0008] Devices or machines for producing foam are also known in which a nozzle must be replaced to modify the quantity of air supplied during foam production. Replacing a nozzle to adapt to the preparation of a particular beverage is therefore not easy and difficult to envisage when the machine or device is in use. This therefore results in a risk of providing customers with a product or hot beverage of relatively uneven quality.

[0009] For example, WO 03 / 092458 A1 discloses a heating and frothing device for milk comprising a steam boiler, an air pump, a milk frother and a control unit. This document describes a method using a calibration member to regulate the flow of pressurized air. Steam is delivered until a temperature sensor detects that the desired temperature for the milk has been reached.

[0010] Document W02016 / 207850A1 discloses a system for heating and emulsifying a liquid, in this case a beverage, via a steam supply circuit and a compressed air supply circuit. Document W02016 / 207850A1 discloses two three-way valves for draining condensation and using a storage tank for a mixture of steam and compressed air. A three-way valve is arranged on either side of said storage tank.

[0011] Statement of the invention

[0012] The object of the present invention therefore aims to overcome the drawbacks of the prior art and to propose a new control method for controlling a device for producing water vapor and pressurized air, the implementation of which is particularly simple and effective for producing a quality emulsion.

[0013] Another object of the present invention is to provide a new method for producing water vapor and air under pressure, to facilitate the preparation of various emulsion finishes with great regularity and reproducibility.

[0014] Another object of the present invention is to propose a new method for producing water vapor and air under pressure, capable of being implemented for the preparation of a very large number of products or hot drinks without having to intervene and carry out structural modifications (for example replacement of nozzles) or adjustments on the machine in which said method is implemented.

[0015] Another object of the present invention is to propose a device for producing water vapor and air under pressure, the construction of which is simple, reliable and ergonomic.

[0016] Another object of the present invention is to provide a computer program intended to implement the control method according to the invention.

[0017] The objects assigned to the invention are achieved using a method for controlling a machine or device for producing and delivering steam and pressurized air to heat and emulsify a food product, consisting of injecting steam and air into the product comprising the steps: - delivering the steam at a constant flow rate for a predefined duration depending on the desired final temperature for the product by feeding a mixer, via a three-way electromagnetic valve which makes it possible to deliver or not the steam and to expose to the atmosphere an additional conduit connecting said mixer to a milk frother, and

[0018] - injecting pressurized air into the product so as to give said product a desired consistency, characterized in that it consists of:

[0019] - to continuously operate an air pump at a nominal speed VN, VNI or VN2 to generate pressurized air,

[0020] - inject water vapor into the product,

[0021] - continuously measure the product temperature,

[0022] - start injecting pressurized air into the product as soon as the temperature T reaches 15°C,

[0023] - control the injection of pressurized air into the product according to one or more cycles C, each cycle C having a total duration dt and including an activation duration d a of the injection and an additional duration of deactivation da of the injection, the duration of activation d a being between 0% and 100% of the total duration dt of cycle C, and

[0024] - stop injecting water vapor into the product as soon as the emulsion obtained has reached a temperature between 60°C and 70°C and preferably equal to 65°C.

[0025] According to an exemplary implementation, the control method consists of interrupting the injection of air into the product simultaneously with interrupting the injection of water vapor into the product.

[0026] According to another exemplary implementation, the control method consists of interrupting the injection of air into the product after a predetermined number of cycles C.

[0027] According to an example of implementation of the method, the activation duration of a in a cycle C is selected from values ​​including 0%, 25%, 50%, 75% and 100% of the total duration dt of cycle C.

[0028] According to an exemplary implementation of the method, a diaphragm pump is used as an air pump to deliver the pressurized air, which is connected to the mixer via a discharge line comprising, respectively in the direction of air flow, a pressure limiter, a flow limiter and a two-way electromagnetic valve, controlled in opening and closing according to a pulse width modulation to respectively activate and deactivate the injection of the pressurized air into the product.

[0029] According to an example of implementation of the method, a nominal rotation speed VN of the air pump is chosen which is substantially constant and less than or equal to the maximum rotation speed of the air pump, during the operating time of said air pump.

[0030] According to another example of implementation of the method, a first nominal rotation speed VNI is chosen for the air pump for an initial duration di of the operating time of said air pump and a second nominal rotation speed VN2 for the remaining part of said operating time, the nominal speed VNI being on the one hand greater than the nominal speed VN2 and on the other hand less than or equal to the maximum rotation speed of said air pump.

[0031] According to an example of implementation, the total duration dt of a cycle C is between 3s and 5s and preferably equal to 4s.

[0032] According to an exemplary implementation, functionalities are selected relating to a production mode in which steam and / or pressurized air are produced or relating to a maintenance mode in which the device is cleaned.

[0033] The objects assigned to the invention are also achieved using a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the method as presented above, when the program operates on a computer.

[0034] The objects assigned to the invention are also achieved by means of a device for implementing the control method as described above, comprising:

[0035] - a steam boiler comprising a tank and temperature, pressure and level sensors to produce pressurized steam, supplying at a constant flow rate a mixer consisting of a portion of T-shaped pipe, via a three-way electromagnetic valve, arranged in a steam supply conduit connecting the boiler tank to the mixer and which makes it possible to deliver or not the steam and to expose to the atmosphere an additional conduit connecting said mixer to a milk frother,

[0036] - an air pump supplying the mixer via a discharge line with pressurized air,

[0037] - the milk frother being equipped with an additional temperature sensor and supplied by the mixer with steam and / or pressurized air,

[0038] - a control unit controlling the operation of the steam boiler, the air pump, the three-way electromagnetic valve and receiving information from the temperature sensors, the low and high level sensors, and where applicable the pressure sensors, and

[0039] - actuating members connected to the control unit to select the desired functionalities, characterized in that the air pump operates continuously at a nominal rotation speed VN, VNI OR VN2 and in that the discharge pipe comprises respectively in the directions of flow of the pressurized air, a pressure limiter, a flow limiter and a two-way electromagnetic valve controlled in opening / closing by the control unit, to supply pressurized air according to determined cycles C.

[0040] According to an exemplary embodiment, the control unit is connected to an electronic card to control the physical parameters necessary to define the different functionalities of said device.

[0041] According to an exemplary embodiment, the control unit is connected to a main electronics integrated into the device, said main electronics comprising a memory card in which the predetermined operating parameters are stored.

[0042] According to another exemplary embodiment, the device comprises an independent electronic box, preferably programmable, capable of being connected to / disconnected from the control unit via a wired or wireless link, for operations of configuring said device, the control unit comprising a memory card in which the predetermined operating parameters originating from the independent electronic box are stored.

[0043] The air pump is advantageously a diaphragm pump.

[0044] The objects assigned to the invention are also achieved using a machine for preparing coffee or hot drinks incorporating a device such as presented above.

[0045] A remarkable advantage of the invention lies in the improvement of the reliability of the device on the one hand and in the regularity over time of the texture of the emulsion on the other hand.

[0046] The user can advantageously take into account specific characteristics of the product to be emulsified. The device can thus adapt to different types of milk, for example of animal or vegetable origin, without altering the optimal texture of the emulsion.

[0047] Another remarkable advantage is linked to the use of a two-way electromagnetic valve and the electronic control of said two-way electromagnetic valve, in particular via triacs. It is thus possible to inject a given quantity of air into the product to be emulsified, with greater precision, thanks to the pulse width modulation control of the two-way electromagnetic valve.

[0048] Brief description of the figures

[0049] Other characteristics and advantages of the invention will appear more clearly on reading the detailed description which follows, given with reference to the appended drawings, given as non-limiting examples, in which:

[0050] - figure 1 is a functional schematic representation of an exemplary embodiment of a device for producing air-steam mixtures in accordance with the invention,

[0051] - figure 2, illustrates an enlarged detail of figure 1,

[0052] - figure 3 is a partial schematic illustration of an example of implementation of the method according to the invention, and

[0053] - figure 4 is a partial schematic illustration of another example of implementation of the method according to the invention.

[0054] Method(s) of carrying out the invention

[0055] Elements that are structurally and functionally identical and present in several distinct figures are assigned the same numerical or alphanumeric reference.

[0056] The device according to the invention comprises a steam boiler 1 for generating pressurized steam. The steam boiler 1 comprises a tank 2 containing water 3. This water 3 is partly transformed into steam 4 by means of an immersed electrical resistance 5. The steam boiler 1 also comprises low level sensors 6, high level sensors 7 and a temperature sensor 8. The low level sensor 6 advantageously constitutes a safety probe for cutting off the power supply to the electrical resistance 5 when the water level in the tank 2 is too low.

[0057] According to an exemplary embodiment, the tank 2 may also include a sensor measuring the pressure prevailing in said tank 2.

[0058] The device also comprises control members, for example a first actuation key 9 and a second actuation key 10, for implementing the various functionalities. The actuation keys 9 and 10, for example push buttons or touch buttons, are connected, for example via an electrical connection 11, to a control unit 12 of the device.

[0059] It is this control unit 12 which makes it possible to control the activation and deactivation of the various functionalities of the device according to instructions. The control unit 12 comprises, for example, various electronic components as well as a memory card in which predetermined operating parameters are stored.

[0060] The control unit 12 can also, according to another exemplary embodiment, be connected via a wired electrical connection 11 to a main electronics unit 13, used to control the operation of the device or of a machine integrating the device according to the invention.

[0061] According to another exemplary embodiment, the device comprises an independent electronic box 13a, capable of being connected to the control unit 12 via another electrical connection 11a, for example wired or wireless, for operations of configuring said device, said control unit 12. The latter then comprises a memory card in which the predetermined operating parameters are stored.

[0062] In this embodiment, the main electronics 13 are no longer necessary, but can be used to control the device and more particularly if the various constituent elements of said device operate within their respective normal operating ranges. For example, the main electronics 13 only allows the device to operate when the temperature read by the temperature sensor 8 is greater than or equal to 110°C.

[0063] Advantageously, it is the user or preferably the manufacturer who records the operating parameters that can be targeted with the device, in the independent electronic box 13a.

[0064] The operating parameters of the device are physical parameters advantageously including the air flow rate, so that the quantity of air in the steam-air mixture is optimal at a given nominal rotation speed, VN, VNI OR VN2 of an air pump 14.

[0065] The operating parameters of the device also include the final temperature of a liquid product 22, which is between 10°C and 100°C. This final temperature is representative of the duration of injection of water vapor into the product 22, for example at a constant flow rate, via a foamer 21.

[0066] For example, the preferred final temperature is at most a temperature between 60°C and 70°C and preferably equal to 65°C to obtain a satisfactory emulsion without degrading the properties of the product 22, in this case milk. The device is also suitable for emulsifying all types of milk, including in particular whole milk, partially skimmed milk, vegetable milk and others.

[0067] The control unit 12 also controls the operation of the air pump 14 via an electrical connection 11. The latter is advantageously a diaphragm pump whose electronic control is more precise and more reliable over time. In addition, a diaphragm pump does not, over time, exhibit wear due to friction as would be the case when using a peristaltic pump.

[0068] The device according to the invention also comprises an air intake nozzle 15 for limiting the air flow. The pressurized air is then supplied via a discharge pipe 16 to a mixer 17. The latter advantageously consists of a portion of T-shaped pipe.

[0069] The discharge line 16 comprises between the air pump 14 and the mixer 17, respectively in the direction of air flow, a pressure limiter 18a, a flow limiter 18c and a two-way electromagnetic valve 18b.

[0070] The air pump 14 makes it possible to produce pressurized air which is necessary to foam the product 22. The air flow rate is determined in particular by the nominal rotation speed VN of the air pump 14 and by the flow limiter 18c.

[0071] Different air flow values ​​can thus be recorded and controlled by means of single, multiple and / or prolonged actuation of one or both control buttons 9 and 10.

[0072] Thus, for example, with a nominal rotation speed VN of the air pump 14, an air flow rate of approximately 2.5 l / min can be obtained.

[0073] The pressure limiter 18a prevents the two-way electromagnetic valve 18b from being subjected to excessively high pressure. Excessively high pressure could negatively affect the quality of the emulsion. The pressure limiter 18a advantageously allows the generated air pressure to be maintained, for example, below 1.5 bar.

[0074] The flow limiter 18c makes it possible to prevent the injection of too much air into the product 22 and to prevent the appearance of excessively large air bubbles in the emulsion. This reduces the risk of negatively affecting the texture of the emulsion. The flow limiter 18c is advantageously a restriction nozzle whose diameter is between 0.2 mm and 0.7 mm.

[0075] The two-way electromagnetic valve 18b is controlled in opening to deliver air to the mixer 17 and this according to precise and, depending on the case, repetitive durations. Advantageously, the two-way electromagnetic valve 18b is controlled, electronically via triacs, to obtain cycles C each having, for example, a duration of 4s.

[0076] Each cycle C includes an activation duration of aof the air injection, corresponding to the opening of the two-way electromagnetic valve 18b and an additional deactivation duration da corresponding to the closing of the two-way electromagnetic valve 18b. We can refer for example to figures 3 or 4.

[0077] The two-way electromagnetic valve 18b also makes it possible, when in the closed position, to prevent the rise of pressurized steam towards the air pump 14 when the operation of the latter is interrupted.

[0078] When the air pump 14 supplies pressurized air, the steam flows towards the foamer 21, since the pressure in the product 22, in this case a liquid, is always lower than the pressure prevailing in the delivery pipe 16.

[0079] According to an exemplary embodiment, the device also comprises a three-way electromagnetic valve 19 arranged in a steam supply conduit connecting it from the tank 2 to the mixer 17. This three-way electromagnetic valve 19 thus makes it possible to open or close the steam passage. The three-way electromagnetic valve 19 is advantageously connected via an electrical connection 11 to the control unit 12.

[0080] The mixer 17 is connected via an additional conduit 20 to a frother 21. The latter is for example immersed in the product 22, contained in a container 23. For example, the additional conduit 20 conveys to the frother 21, the water vapor alone or a mixture of steam and air under pressure.

[0081] The air pump 14 must supply pressurized air into the discharge line 16 and therefore to the mixer 17, at a pressure at least equal to or greater than the water vapor pressure coming from the tank 2.

[0082] According to one embodiment, the device also comprises an additional temperature sensor 24 arranged for example on the foamer 21 and electrically connected via an electrical connection 11 to the control unit 12. This additional temperature sensor 24 makes it possible to measure the temperature of the product 22 and to stop, via the control unit 12, the delivery of steam by closing the three-way electromagnetic valve 19 and, if necessary, by interrupting steam production, when the desired final temperature for said product is reached. The foamer 21 advantageously comprises at its free end an expulsion nozzle 25 for pressurized air, water vapor or a mixture of water vapor and pressurized air. The dimensions and shapes of this expulsion nozzle 25 are adapted to the production of foam and are known. They are therefore not described further.

[0083] The aerator 21 advantageously integrates the additional temperature sensor 24. This makes it possible to avoid having to use an assembly comprising a temperature probe remote from the aerator 21 and simultaneously immersed in the product 22. The construction of the assembly is thus simplified and much easier to handle and clean.

[0084] According to an example of operation of the device, illustrated for example in Figure 3, the user first actuates the first control button 9. The air pump 14 starts up with a nominal rotation speed VN adapted to the generation of a given air flow. The nominal speed VN is reached gradually. Initially, the two-way electromagnetic valve 18b is open during a purge phase until time t p This purge phase lasts for example 500 ms.

[0085] The operation of the air pump 14 is controlled by the control unit 12. The air drawn in through the air inlet nozzle 15 is discharged via the pressure limiter 18a, the flow limiter 18c and the open two-way electromagnetic valve 18b, to the mixer 17.

[0086] Simultaneously, with an actuation of the second control button 10, the control unit 12 controls the opening and closing of the three-way electromagnetic valve 19. The opening of the three-way electromagnetic valve 19 makes it possible to convey pressurized steam to the mixer 17. The latter makes it possible to mix the steam coming from the boiler 1 and the air coming from the air pump 14. The steam-air mixture thus produced is then conveyed to the frother 21 partially immersed in the product 22, for example milk.

[0087] Beforehand, only water vapor is injected into the product 22. As soon as the temperature of the product 22 reaches or exceeds a minimum temperature, for example 15°C, at time ti, the two-way electromagnetic valve 18b will be controlled to move into its open position and allow the mixer 17 to be supplied with air.

[0088] The additional temperature sensor 24, connected to the control unit 12, allows the latter to be informed of the temperature of the product 22. When the predefined and desired final temperature of the product 22 is reached, the three-way electromagnetic valve 19 is actuated and interrupts the injection of steam alone or of the air-steam mixture.

[0089] For example, the two-way electromagnetic valve 18b is controlled to close simultaneously with the interruption of the steam injection or subsequently when a predefined air injection duration is reached.

[0090] Furthermore, the third way of the three-way electromagnetic valve 19 allows the additional conduit 20, which is in fluid connection with the foamer 21, to be vented to the atmosphere, in order to prevent the product 22 from being sucked into said additional conduit 20. Such suction may result from a drop in pressure or vacuum caused by the condensation of water vapor in the additional conduit 20.

[0091] The control method according to the invention is described below, for example, with an example of implementation illustrated in Figure 3.

[0092] Thus, to produce an emulsion in the product 22, the air pump 14 is started at time to to continuously operate, which gradually reaches its nominal speed VN to generate pressurized air.

[0093] At the same time, the injection of water vapor into the product 22 is started at time to, in order to heat the product 22, and the temperature of said product 22 is continuously measured. The latter is generally stored, before use, at a temperature of approximately 5°C when it is milk.

[0094] When the temperature of product 22 reaches 15°C, at time ti, the injection of pressurized air into product 22 begins.

[0095] Advantageously, the injection of pressurized air into the product 22 is controlled for one or more cycles C. Each cycle C advantageously includes an activation duration d aof the air injection and an additional deactivation duration da of the air injection, the activation duration being between 0% and 100% of the total duration dt of cycle C. The activation and deactivation of the air injection correspond respectively to the opening and closing of the two-way electromagnetic valve 18b.

[0096] An activation duration of a of 0%, corresponds to a situation where no air is supplied to the mixer 17, because the two-way electromagnetic valve 18b is closed and consequently no emulsion is generated.

[0097] Furthermore, an activation duration of a of 100%, corresponds to a situation where the quantity of air injected into the product 22 is maximum.

[0098] The injection of steam and pressurized air into the product 22 is interrupted, preferably automatically, as soon as the emulsion obtained reaches, for example, 65°C at time t3. Alternatively, it may be provided that the injection of air into the product 22 continues for a determined and predefined duration after the interruption of the injection of steam into said product 22. This is the case if the injection of air must comprise a minimum number of cycles, corresponding for example to a duration of 20s, to be interrupted at a time beyond time t3.

[0099] According to an example of implementation of the method, the activation duration of a during a cycle C is selected from values ​​including 0%, 25%, 50%, 75% and 100% of the total duration dt of a cycle. It is thus possible to adapt the device to different types of products 22 to obtain an optimal texture of the emulsion in all situations.

[0100] According to another example of implementation of the method, illustrated in Figure 4, a first nominal speed VNI is chosen for the air pump 14 until time t2, that is to say for an initial duration di (di=t2-to) of the operating duration of the air pump 14 and a second nominal speed VN2 during the remaining part of said operating duration. The initial duration di makes it possible to improve and make more reliable the priming of the air pump 14.

[0101] The nominal speed VNI is on the one hand greater than the nominal rotation speed VN2 and on the other hand less than or equal to the maximum rotation speed of said air pump 14. For example, the nominal rotation speed VNI of the air pump 14 corresponds to 60% of its maximum rotation speed and the nominal rotation speed VN2 corresponds to 50% of its maximum rotation speed during the remaining duration of the activation of the air pump 14.

[0102] According to an exemplary implementation, the total duration of a cycle C of the air pump 14 is between 3s and 5s and preferably equal to 4s.

[0103] Thus, according to an example of operation of the device, when the steam boiler 1 is at a temperature of 122°C, with an internal pressure of between 0.9 bar and 1.2 bar, preferably equal to 1.1 bar, with an air flow rate at the outlet of the air pump 14 of between 2.2 1 / min and 2.5 1 / min, with a flow limiter 18c having a diameter of 0.2 mm, and an activation time of a of 1s, the time to obtain an emulsion at 65°C starting from 250 ml of milk at 5°C, is approximately 50s.

[0104] The invention also relates to a computer program product which can be loaded into a memory unit associated with a microprocessor of the control unit 12 or of the main electronics 13, to control the implementation of the steps of the method as presented above, when the instructions of said computer program product are executed on said control unit 12.

[0105] According to an exemplary implementation in accordance with the invention, the method also consists of selecting functionalities relating to a maintenance mode in which the machine or device is cleaned. In this maintenance mode, the three-way electromagnetic valve 19 is controlled to deliver the water vapor in the form of successive pulses. The three-way electromagnetic valve 19 is for example open for 2s, then closed for 5s. This cycle is then repeated for example for 3 minutes. Certain opening and closing pulses may advantageously have a longer duration, for example 10s and 30s respectively, to optimize the cleaning and / or unblocking operation.

[0106] The various functionalities in production mode of the device according to the invention are controlled for example by the specific actuation, respectively long and / or short, repetitive or not, of each of the control keys 9 and 10.

[0107] For example, to initiate the maintenance mode, the power supply to the machine incorporating the device according to the invention must be cut off, then said power supply must be restored by simultaneously pressing one of the two control keys 9 or 10 for a predetermined duration, for example 3 seconds. The maintenance mode then starts automatically. When the maintenance mode is finished, the production mode is automatically initiated again and the device according to the invention awaits actuations of the control keys 9 and 10.

[0108] It is obvious that the present description is not limited to the examples explicitly described, but also includes other embodiments and / or implementations. Thus, a described technical feature or a described implementation step may be replaced respectively by an equivalent technical feature or an equivalent step, without departing from the framework and scope of the invention defined by the claims.

Claims

CLAIMS 1. Method of controlling a machine or device for producing and delivering pressurized steam and air to heat and emulsify a food product (22), consisting of injecting steam and air into the product (22), comprising the steps: - deliver the steam at a constant flow rate for a predefined duration depending on the desired final temperature for the product (22) by supplying a mixer (17), via a three-way electromagnetic valve (19) which allows the steam to be delivered or not and to expose to the open air an additional conduit (20) connecting said mixer (17) to a milk frother (21), and - injecting pressurized air into the product (22) so as to give said product (22) a desired consistency, characterized in that it consists of: - to continuously operate an air pump (14) at a nominal speed VN, VNI or VN2, - inject water vapor into the product (22), - continuously measure the temperature T of the product (22), - start injecting pressurized air into the product (22) as soon as the temperature T reaches 15°C, - control the injection of pressurized air into the product (22) during one or more cycles C, each cycle C having a total duration dt and including an activation duration d a of the injection and an additional duration of deactivation da of the injection, the duration of activation d a being chosen and between 0% and 100% of the total duration dt of cycle C, and - interrupt the injection of water vapor into the product (22) as soon as the emulsion obtained has reached a temperature between 60°C and 70°C and preferably equal to 65°C.

2. Control method according to claim 1, characterized in that it consists of interrupting the injection of air into the product (22) simultaneously with the interruption of the injection of water vapor into the product (22).

3. Control method according to claim 1, characterized in that it consists of interrupting the injection of air into the product (22) after a predetermined number of cycles C.

4. Control method according to any one of claims 1 to 3, characterized in that the activation duration of a in a cycle C is selected from values ​​including 0%, 25%, 50%, 75% and 100% of the total duration dt of cycle C.

5. Control method according to any one of claims 1 to 4, characterized in that it consists of using a diaphragm pump as an air pump (14) to deliver the pressurized air, which is connected to the mixer (17) via a discharge pipe (16) comprising respectively in the direction of air flow, a pressure limiter (18a), a flow limiter (18c) and a two-way electromagnetic valve (18b) controlled in opening and closing according to a pulse width modulation to respectively activate and deactivate the injection of pressurized air into the product (22).

6. Control method according to any one of claims 1 to 5, characterized in that it consists of choosing for the air pump (14) a nominal rotation speed VN which is substantially constant and less than or equal to the maximum rotation speed of said air pump (14) during the operating time of said air pump (14).

7. Method according to any one of claims 1 to 5, characterized in that it consists in choosing for the air pump (14) a first nominal rotation speed VNI for an initial duration di of the operating duration of the air pump (14) and a second nominal rotation speed VN2 during the remaining part of said operating duration, the nominal speed VNI being on the one hand greater than the nominal speed VN2 and on the other hand less than or equal to the maximum rotation speed of said air pump (14).

8. Control method according to any one of claims 1 to 7, characterized in that the total duration dt of a cycle C is between 3s and 5s and preferably equal to 4s.

9. Control method according to any one of claims 1 to 8, characterized in that it consists of selecting functionalities relating to a production mode in which steam and / or pressurized air is produced or relating to a maintenance mode in which the device is cleaned.

10. Computer program product comprising code instructions program recorded on a computer-readable medium for implementing the steps of the method according to any one of claims 1 to 9, when the program operates on a computer.

11. Device for implementing the control method according to any one of claims 1 to 9, comprising: - a steam boiler (1) comprising a tank (2) and low level (6), high level (7) and temperature (8) sensors, for producing pressurized steam, supplying a mixer (17) consisting of a portion of T-shaped pipe, via a three-way electromagnetic valve (19) arranged in a steam supply conduit (la) connecting the tank (2) of the boiler (1) to the mixer (17) and which makes it possible to deliver or not the water vapor and to expose to the open air an additional conduit (20) connecting said mixer (17) to a milk frother (21), - an air pump (14) supplying the mixer (17) via a discharge line (16) with pressurized air, - the milk frother (21) being provided with an additional temperature sensor (24) and supplied by the mixer (17) with steam and / or pressurized air, - a control unit (12) controlling the operation of the steam boiler (1), the air pump (14), the three-way electromagnetic valve (19) and receiving information from the temperature sensors, low and high level sensors (6, 7, 8, 24), and - actuating members (9, 10) connected to the control unit (12) to select the desired functionalities, characterized in that the air pump (14) operates continuously at a nominal rotation speed VN, VNI OR VN2 and in that the discharge pipe (16) comprises respectively in the direction of flow of the pressurized air, a pressure limiter (18a), a flow limiter (18c) and a two-way electromagnetic valve (18b) controlled in opening / closing by the control unit (12), to supply pressurized air according to determined cycles C.

12. Device according to claim 11, characterized in that the control unit (12) is connected to a main electronics unit (13) integrated into said device, said main electronics unit (13) comprising a memory card in which the predetermined operating parameters are stored.

13. Device according to claim 11, characterized in that it comprises an independent electronic box (13a), capable of being connected to / disconnected from the control unit (12) by wired or wireless connection for configuration operations of said device, said control unit (12) comprising a memory card in which the predetermined operating parameters from said independent electronic box are stored.

14. Device according to any one of claims 11 to 13, characterized in that the air pump (14) is a membrane pump.

15. Machine for preparing coffee or hot drinks, characterized in that it incorporates a device according to any one of claims 11

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