RU2811557C1 - Mixing device - Google Patents

Abstract

FIELD: mixing device.

SUBSTANCE: mixing device contains a first hole for receiving milk, a second hole for receiving steam and a mixing chamber for mixing milk, steam and air. The channel structure connects the holes and also forms an air intake channel that leads to the foaming section. An adjustment element is provided for adjusting the seal near the air intake duct to thereby control the level of foaming.

EFFECT: mixing device is proposed.

9 cl, 16 dwg

Description

TECHNICAL FIELD

The present invention relates to the field of preparing beverages, and more particularly to the field of preparing foamed milk drinks.

BACKGROUND OF THE ART

As a rule, espresso devices have a cappuccino brewing function. In most cases, steam is used to heat and froth the milk, much like a barista would. To improve the usability of the device and ensure consistent performance for all users, regardless of their qualifications, several milk frothing modules have been developed. Typically these modules are designed to be removable from the base unit, since all parts in contact with the milk must be cleaned.

The applicant has developed a milk frothing system that contains only two detachable components, allowing it to be easily cleaned by the user. This design is disclosed in WO 2019/129599 and WO 2019/1029515.

The ratio of foam to milk and therefore the amount and/or consistency of foam is fixed in conventional milk frothing modules. The user can turn off (stop) the frothing process before it is finished, but this does not change the foam to milk ratio.

It would be desirable for the user to be able to select a preferred milk to foam ratio in order to be able to adjust the quantity and/or quality of the foam. However, there is no simple, low-cost solution that allows for this type of foam selection.

DISCLOSURE OF THE INVENTION

The invention is defined by the claims.

According to the examples, in accordance with one aspect of the invention there is provided a mixing device comprising:

the first hole for receiving milk;

second hole for steam intake;

mixing chamber for mixing milk, steam and air and

a channel structure between the first and second openings and the mixing chamber, the channel structure comprising:

a first channel portion connected between the first hole and the foaming section;

a second channel portion connected between the second hole and the foaming section; And

air intake duct to the foaming section; And

a seal forming the surface of the first and second channel sections and the air intake channel,

wherein the foaming section is connected to the mixing chamber, and the mixing device further includes an adjustment element for adjusting the seal near the air intake channel, thereby adjusting the level of foaming.

This mixing device has a channel structure that brings milk, steam and air together to create heated and frothed milk. The foam is created by air introduced through the air intake duct.

The seal closes the channel structure and thereby forms one surface of the air intake channel. By providing an adjusting element for adjusting the seal at or near the air intake passage, the resistance to air flow is adjusted, and thus the level of foaming can be adjusted.

The mixing device may contain:

a first container containing a channel structure; And

a second container configured to receive the first container;

wherein the seal is located between the first container and the second container.

This configuration allows milk and steam to be supplied to the mixing chamber through a channel formed at least in part by the seal. Thus, the channel can be disassembled for cleaning by simply removing the first container from the second container, since the channel structure contains only these two separable parts.

In addition, since the channel itself is partially formed by the seal when positioned between the first and second containers, proper sealing of the channel is ensured. Placing the two containers together provides the desired seal location and/or compression or expansion.

The first container may further comprise a projecting channel portion, wherein a channel structure is formed between the projecting channel portion and the seal.

In this way, the dimensions of the channel can be controlled by changing the height of the projecting channel portion, and the necessary cleaning of the seal is simplified.

The adjusting element, for example, includes a pusher for pushing the seal into the air intake duct.

This ensures that the air intake channel is restricted, thereby changing the air flow and therefore the level of foaming.

The mixing device may comprise an outlet nozzle from which frothed milk is to be dispensed from the mixing chamber, wherein the adjustment member comprises an adjustment ring around the outlet nozzle, wherein the adjustment ring operates a pusher, and wherein the adjustment ring is rotatable to adjust the advance. pusher to the air intake duct.

This provides a simple user interface to adjust the foam level by simply selecting the angular position of the adjustment ring around the outlet nozzle.

The adjusting ring, for example, includes a curved surface for actuating the pusher. Thus, the ring simply turns, and this rotation is converted into a linear push by a curved surface.

The adjusting element, for example, has at least three positions comprising:

position for maximum foam level;

position for intermediate foam level and

position without foam formation.

The foam setting may be continuously adjustable between maximum foam and no foam positions, or there may be one or more discrete positions in between.

The seal, for example, includes a sealing seal. A closure seal is a seal that extends through and beyond the hole and thus acts as a closing cap on the hole. Thus, it covers the entire area of the opening being sealed, rather than forming a seal around a separate closing part. The term "overlapping seal" is used to refer to this general type of sealing configuration.

A flashover seal works using pulling forces that stretch the seal rather than compress it. This results in a slow increase in indentation force, which means manufacturing tolerances are easier to overcome without adding a lot of unnecessary force. The overlap seal provides compaction directly to the channel structure without significant deformation, making it easier to control the geometry of the channel structure.

In addition, according to the invention there is provided a coffee maker comprising:

device for producing liquid coffee extract;

a mixing device as defined above; And

dispensing device configured to dispense:

liquid coffee from a device for obtaining liquid coffee extract and

frothed milk from the mixing device.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention are described in detail below with reference to the accompanying drawings, in which:

In FIG. 1 shows a two-component mixing device;

In FIG. 2A is a detailed exploded view of the mixing device of FIG. 1;

In FIG. 2B shows the mixing device of FIG. 2A assembled;

In FIG. 3A shows a detailed view of the channel of the mixing device of FIG. 2A;

In FIG. 3B shows the fluid flow passing through the channel of FIG. 3A;

In FIG. 4A shows an example of a seal seal;

In FIG. 4B shows the operation of the overlap seal of FIG. 4A;

In FIG. 5A shows an alternative channel of the mixing device;

In FIG. 5B is a cross-sectional view of the channel of FIG. 5A;

In FIG. 6 shows an example of a transition section of the seal;

In FIG. 7 shows the upper part of the channel structure for determining the X-X cross section;

In FIG. 8 is a cross-sectional view along X-X as shown in FIG. 7, the known design of FIG. 1-6;

In FIG. 9A-9C show a typical adjuster that pushes the seal downward, and various degrees of pushing the seal into the air intake duct are shown;

In FIG. 10 shows how the approach of FIG. 9A-9C can be applied to the mixing device described above as a modification of the design of FIG. 8;

In FIG. 11 is a side view of the mixing device showing the adjustment ring around the outlet nozzle; And

In FIG. 12A-12C show the arrangement of FIG. 10 in three different foaming positions.

IMPLEMENTATION OF THE INVENTION

The invention provides a mixing device having a first opening for receiving milk, a second opening for receiving steam, and a mixing chamber for mixing milk, steam and air. The channel structure connects the holes and also defines the air intake channel that leads to the foaming section. An adjustment member is provided for adjusting the seal near the air intake duct to thereby control the level of foaming.

In FIG. 1 shows a mixing device 100 including a first container 110 and a second container 120 configured to receive the first container 110. The second container may surround the first container, or it may only partially surround the first container, as shown. The second container 120 defines an outlet nozzle 122 from which frothed milk is supplied. Thus, the first container may fit entirely within the second container, or the second container may be snap-attached to the outside of the first container.

A channel structure is formed at the interface between the first and second containers, as described in more detail below. The seal 130 provides a seal to the channel structure. When the first and second containers are separated, the channel structure is exposed. In the embodiment shown, the seal 130 is visible on the outside of the second container 120 because in this example it extends completely through the wall of the second container. The visible outer surface of the seal serves no function; on the contrary, it is simply an aesthetic design option. The inner surface of the seal closes the channel sections of the channel structure.

In FIG. 2A shows the mixing device 100 in more detail, and depicts a first container 110, a second container 120 configured to receive the first container, and a seal 130 located between the first and second containers.

Instead of being integral with the container and extending completely through the wall of the container, the seal may be press-fitted into the side wall of one of the two containers so that when the two containers are assembled, the seal is located between them. In all designs, the interface between the seal and the channel structure in one of the containers defines a closed channel that defines fluid paths between the milk inlet, the steam inlet, and the frothed milk outlet of the mixing device 100. By separating the two containers, all parts can be easily cleaned. Preferably, only one sealing element is used to seal the entire channel structure used for supplying and mixing milk and steam.

The seal may be incorporated into the second container 120 by two-step (2K) injection molding, or it may be a separate seal that is removable from a recess in the second container.

The channel structure 140 may be formed in the first container 110 and, together with the seal 130, may form a closed channel when the mixing device is assembled. In the example shown in FIG. 1, the first container 110 includes a protruding channel portion 145 that further defines a channel structure 140. The channel structure 140 connects a first opening 150 near the bottom of the first container and a mixing chamber 160 near the top of the first container. The second container includes a steam inlet (indicated by reference numeral 175 in FIG. 2B), which is connected to a second opening 170 formed in the seal 130. A channel structure 140 further connects the second opening 170 to the first opening 150 and the mixing chamber.

In FIG. 2B shows the mixing device 100 of FIG. 1A in assembled condition.

This drawing clearly shows that the second container 120 includes a steam injection port 175, from which steam can be supplied to the second port 170. The second container 120 further includes a third port 180, which, when assembled, is connected to the mixing chamber 160 of the first container, in whereby it is possible to conveniently obtain the contents of the mixing chamber from the mixing device. The third opening 180 leads to an outlet nozzle 122 (not shown in FIG. 2A or 2B, but shown in FIG. 1). The operation of the mixing device is described with reference to FIG. 3A below.

In FIG. 3A shows a detailed view 200 of the channel structure 140 of the mixing device of FIG. 2A. In FIG. 3B is a simplified view of the intersection of various portions of channel structure 140.

The channel structure 140 may be divided into several sections according to the work performed by each section. During operation, milk may be supplied to the first container 110, and steam may be supplied to the steam inlet 175 of the second container. As steam enters the channel structure 140 through the second opening 170, milk 215 is drawn from the first container 110 into the first channel section 210 through the first opening 150. Steam 225 enters the second channel section 220 and passes through the third channel section 230 (hereinafter also referred to as the foaming section). into the mixing chamber 160. The steam flow creates a reduced pressure (relative to ambient pressure) in the third channel section 230, thereby drawing milk 215 along the first channel section 210. The steam is then used to heat the milk and mix the milk with air and thus , forms the driving force of the entire foaming system.

Milk 215 is drawn along the first channel section 210 until it encounters the steam flow 225 at the intersection of channel sections 210 and 230. This intersection may be at the central portion of the third channel section 230 immediately downstream of a throat formed between the second channel section. section 220 and a third channel section 230. At this throat, the steam is significantly accelerated, thereby providing a Venturi effect (a decrease in fluid pressure resulting from a narrowing of the throat) acting on the steam as it passes into the third channel section 230.

In this way, the static absolute steam pressure (which in this example could, for example, be approximately 1.9 bar=190 kPa) is converted into dynamic pressure (velocity). Milk is absorbed as a result of a decrease in pressure. The steam velocity is highest at the end of the throat, i.e. where the first channel section 210 intersects the third channel section 230. The second part of the third channel section 230, i.e. the area downstream of the throat and the aforementioned intersection can be considered to function as a diffuser in which the speed of the milk and steam mixture is slowed down, converting the dynamic pressure back to static pressure.

The third channel portion 230 terminates at an end 235 that opens into the mixing chamber 160. At the end 235 just before the mixing chamber an air intake passage 725 is formed through which air is introduced into the milk/steam mixture. The flow rate of the milk/steam mixture near the air intake duct is such that the static pressure is still lower than the ambient pressure, so that air is drawn in and the milk/steam mixture is prevented from leaking. The introduced air creates bubbles for the desired foaming. In the mixing chamber 160, the mixture of milk, steam and air reaches ambient static pressure and the velocity component or dynamic pressure returns to zero.

Thus, the steam experiences the Venturi effect at the throat. This is the leading (active) effect, controlling the flow of milk as a slave (passive) effect. This Venturi effect in the third channel section 230 can be achieved by simply limiting the cross-sectional area of the third channel section 230 relative to the second channel section 220. The flow of milk and steam in the third channel section in combination with air suction determines the foaming characteristics of the mixing device, and pressure drops are prevented leakage of milk and steam through the wrong channels.

The first channel portion 210 may generally be vertical in use and may extend upward from the first (milk inlet) opening 150. In the upper part, it can be connected on one side to the second channel section 220, at the distal end of which there is a steam inlet hole 175, and on the other hand it is connected to the third channel section 230, at the distal end of which the mixing chamber 160 is located. Thus, in the embodiment shown, the channel structure 140 is T-shaped and the seal 130 is correspondingly T-shaped.

The seal 130 may be integral with the second container. Alternatively, it may be a removable seal, in which case it may be press-fitted into the side wall of the second container 120. In some cases, the seal 130 may include a first sealing element 240 and a transition portion 250. This will be described in more detail with reference to FIG. 6.

As explained above, air is drawn in through the air intake passage 725 at the end 235 of the third passage portion 230 so that a mixture of milk, steam and air is supplied to the mixing chamber 160. The purpose of the mixing chamber is to release large bubbles and retain only small air bubbles in the mixture. The mixture of air, milk and steam forms a fluid that enters the mixing chamber.

In FIG. 4A seal 130 of FIG. 3A is shown in more detail.

From the above description, it is clear that the various channel sections 210, 220, 230 may be subject to a variety of different conditions during operation of the mixing device 100. Consequently, the respective sealing areas of these channel sections may have their own sealing requirements or specifications. The seal areas can be combined into a single seal, such as an overlapping seal, as shown. The technical characteristics of the respective seal areas can be easily optimized, for example by locally varying the thickness of the seal. By combining different areas of the seal seal into one seal seal, there is no risk of leakage when transitioning between different areas of the seal seal.

There are three parameters that can be adjusted to adjust the sealing force of the overlap seal. These three parameters are: Shore hardness of the seal; the width of the seal overlap, which increases the compacting force, but may also cause some deformation of the channel; and seal thickness. Since different areas of the overlap seal can be adjusted using overlap width and seal thickness, the risk of leakage is greatly reduced since the need for transitions between different seals is eliminated.

For example, the seal may include a first sealing portion 310 for sealing the first channel portion 210. Thus, the first sealing portion must be configured to withstand the reduced pressure present in the first channel portion. Since this pressure is usually low, for example about 0.15 bar (15 kPa), and below ambient pressure, the sealing force required is small; however, the first channel section may be relatively long, for example 200 mm, which means that the required sealing force is increased. Since the milk is at a low temperature at this stage and the dimensions of the first channel portion are not critical to the milk foaming process, the compacting force of the first compacting portion can be increased by simply increasing the width of the overlap.

As yet another example, the seal may include a second sealing portion 320 for sealing the second channel portion 220. In this case, the second sealing portion must withstand both high pressure, such as 1 bar (100 kPa), and high temperature, such as 105° C., steam , entering the channel. As with the first channel section, the geometry of the second channel section is not critical to the milk frothing process, which means that the overlap width of the second sealing section can be increased to increase the sealing force, and the seal thickness can be increased to both increase the sealing force of the second sealing section, and to increase the resistance of the second sealing section to high steam temperatures.

As a final example, the seal may include a third sealing portion 330 for sealing the third channel portion 230. The dimensions of the third channel portion are critical to the milk frothing process and the tolerance for deformation is low, for example ±0.1 mm. Therefore, the overlap width of the third sealing portion cannot be arbitrarily increased, and the thickness of the seal provides only a slight advantage to the compacting force itself. In this case, the Shore hardness of the seal provides the required sealing force. The Shore hardness of the seal may be constant, for example 45 Shore, throughout the seal to avoid excessive overlap widths and seal thicknesses in the first and second seal portions. In addition to the milk frothing process, the seal must withstand daily cleaning, usually with a dishwasher. In this case, the Shore hardness of the seal can help extend seal life.

Finally, the seal in the illustrated embodiment includes a first sealing element 240 which, when assembled, provides a radial seal around the mixing chamber 160. Three sealing portions 310, 320, 330 are overlap seals while the first sealing element 240 is a radial seal. The overlap seal cannot be used to seal the mixing chamber because a hole is required to allow the frothed milk to exit. The three sealing portions and the first sealing element preferably together form a single integrated component.

In FIG. 4B shows the operation of one portion of the seal seal 130.

The overlap seal works using pull forces (FP), which stretch the seal over the channel structure rather than compressing it. The overlap seal provides a seal to the channel structure itself, more specifically to the projecting channel portions 145, without significant deformation of the seal. The cross-sectional size and shape of the channel structure 140 is independent of indentation and compaction forces, resulting in more consistent milk foam characteristics, particularly in the third compaction region 330.

In FIG. 5A and 5B show a detailed view of an alternative channel structure 400.

In this case, the seal 410 includes a raised seal portion 415 that defines a channel 420 in conjunction with the first container 110. This arrangement makes the first container easier to clean because there are fewer raised areas in which ingredients can get stuck. In this case, it may be necessary to further increase the Shore Hardness of the seal to ensure that the seal protrusion 415 does not deform under high pressure causing leakage.

In FIG. 6 shows a seal 700 including a first sealing element 240, a sealing portion 710, and a transition portion 250 therebetween. The top image shows a front view of the seal 700 located in the second container 120. The bottom image shows a perspective view of the opposite container 110 with the mixing chamber 160, the end portion of the channel structure 140, and the assembled portion of the first sealing element 240 providing a seal around the mixing chamber 160.

As described above, the sealing element 240 may be a radial seal surrounding the mixing chamber 160; sealing portion 710 may correspond to a set of overlap seals 310, 320, 330 described with reference to FIG. 4A. The first seal element 240 includes a seal gap 720 located in the transition portion 250. The seal gap 720 allows milk and steam from the channel formed by the seal portion 710 to flow into the mixing chamber 160. Thus, the overlap seal 710 and the radial seal 240 can be combined into one one-piece seal and thereby increase the ease of disassembly and cleaning of the mixing device. However, it is known that the transition region 250 between both types of seals is susceptible to leakage due to abrupt transitions (eg, thickness) between both types of seals. The risk of leakage may further be exacerbated by rupture of the seal 720. The design shown turns this potential disadvantage into an advantage by placing the air inlet in said transition portion.

As can be seen from the bottom image of FIG. 6, the channel structure 140 in this example is formed by the raised channel portions 145 of the first container 110. These raised portions define the sides of the channel structure to which a closure seal 710 is applied. At least one of the raised channel portions 145 adjacent to the mixing chamber 160 is formed gap 725. A gap 725 is formed immediately in front of the mixing chamber adjacent to the seal break 720. The gap 725 opens into the space between the first and second containers and allows external communication with the end 235 of the third channel portion 230 (as shown in FIG. 3A). Thus, the gap 725 defines an air intake passage through which outside air can enter the end 235 of the third passage portion 230.

The speed of liquid (milk, steam and air) entering the mixing chamber 160 is important to the quality of the foam. The distance between the milk venturi and the air gap 725 and the distance between the air gap and the mixing chamber are parameters for determining the milk frothing characteristics.

Said mixing device is known to the extent that it is described above, and indeed FIG. 2-6 taken from WO 2019/129599 and WO 2019/1029515.

The present invention relates to the control of foam levels. The invention is described as a modification of the structure shown in FIG. 1-6, but the basic concept can be applied to other mixing device designs. The invention relates in particular to the control of an air inlet used to create foam and provides an adjustable sealing function.

In FIG. 7 shows the top of the channel structure 140 and a cross-section along line X-X.

In FIG. 8 is a sectional view taken along line X-X shown in FIG. 7, the known design shown in FIG. 1-6. The first container 110 defines the mixing chamber 160, and the second container 120 defines the outlet nozzle 122. The seal 130 is integral with the second container 120 and is shown extending completely across the second container.

In FIG. 8 shows the end of the third channel portion 230, particularly the location where air is drawn into the channel structure 140, and thus shows the portion of the air intake passage 725.

The seal 130 defines the surface of the air intake passage 725 as shown, as well as the surface of the first and second passage portions (not shown in FIG. 8).

The present invention uses an adjustment member to adjust the seal 130 adjacent the air intake passage 725, thereby controlling the level of foaming.

The air intake duct is, for example, a straight hole. Since the milk and steam mixture moves rapidly past the opening into the air intake duct (i.e. has high dynamic pressure), its static pressure is lower than the ambient pressure as stated above. For this reason, air is sucked in at the end 235 of the third channel portion or foaming section 230. Thus, milk is sucked into the central part of the foaming section 230 (just after the end of the throat at the entrance to the foaming section) due to the low pressure created by the high steam flow rate. At the air inlet there is a relatively high-speed flow of steam-milk mixture, while at the milk inlet there is a high-speed flow of steam. The speed of steam is much higher than the speed of the steam mixture at the air inlet. The milk suction pressure is, for example, 150 mbar (15 kPa) lower than ambient pressure. At the air inlet, the suction pressure is, for example, several hundred Pa (lower than ambient pressure).

Although in FIG. 3B, the end portion of the foaming section 230 leading to the end 235 is shown as a straight channel and may have a conical shape. Within the foaming section immediately downstream of the milk inlet there is an area corresponding to the preceding neck section. This area can gradually increase in the downstream direction until it exits into the mixing chamber.

Pushing the seal 130 into the channel structure 140 occurs at the larger area end 235 of the foaming section 230 adjacent to the mixing chamber outlet and adjacent to the air inlet position.

Thus, the seal adjustment "near the air intake duct" may be in the side position of the air intake duct or in part of the foam section.

In FIG. 9 shows an exemplary adjuster 900 that pushes the seal 130 downward to force it into the air intake duct 725 (or foam section portion).

In FIG. 9A shows the adjustment element 900 which does not deform the seal so that maximum air intake duct area is provided. In FIG. 9B shows adjuster 900 partially pushing the seal into the air intake duct to reduce air flow. In FIG. 9C shows adjuster 900 further pushing the seal into the air intake duct to reduce air flow by the maximum amount.

The three provisions shown may include:

position for maximum foam level;

position for intermediate foam level and

position without foam formation.

In FIG. 10 shows how this approach can be applied to the mixing device described above and shows a modification to FIG. 8.

The adjusting member includes a pusher 905 for pushing the seal 130 into the air intake passage 725. The adjusting member also includes an adjusting ring 910 around the outlet nozzle 122, the pusher 905 being actuated by the adjusting ring 910. The adjusting ring is rotatable to adjust the advancement of the pusher 905 towards the air intake passage . This provides a convenient user interface for adjusting the foam level by simply selecting the angular position of the adjustment ring around the outlet nozzle.

The adjusting ring 910 has a curved surface 915 for driving the pusher 905. Thus, the ring is simply rotated, and this rotation is converted into linear pushing by the curved surface. The pusher can be injection molded into the 130 seal and only moves in and out.

In FIG. 11 is a side view of the mixing device showing the adjustment ring 910 around the outlet nozzle 122.

The foam level setting may be continuously adjustable between the maximum and zero foam level positions by rotating the adjustment ring, or there may be one or more discrete intermediate positions, such as flat areas of a curved surface.

In FIG. 12 shows the arrangement of FIG. 10 at three different positions: zero foam level position (FIG. 12A); a position for medium foam level (FIG. 12B) and a position for maximum foam level (FIG. 12C).

The amount of compression or movement of the seal can be only tenths of a millimeter to about 1 mm or 2 mm, thereby reducing the channel area.

For example, the non-foaming position allows the delivery of hot milk mixed with other flavors such as chocolate. When the seal is pressed even further into the air intake duct, the volume becomes very small.

Those skilled in the art can understand and implement other variations of the disclosed embodiments based on examination of the drawings, disclosure, and appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the grammatical means of expressing the singular do not exclude the presence of the plural. The mere fact that certain dimensions are specified in different dependent claims does not mean that a combination of these dimensions cannot be used to advantage. No reference symbols in the claims should be construed as limiting the scope of the invention.

Claims (25)

1. A mixing device (100) for creating foamed milk, containing: a first hole (150) for receiving milk; a second hole (170) for receiving steam; mixing chamber (160) for mixing milk, steam and air and a channel structure (140) between the first and second openings and the mixing chamber, the channel structure comprising: a first channel section (210) connected between the first hole (150) and the foaming section (230); a second channel section (220) connected between the second hole (170) and the foaming section (230); And air intake duct (725) to the foaming section; And a seal (130) forming the surface of the first and second channel sections and the air intake channel, wherein the foaming section is connected to the mixing chamber, and the mixing device additionally contains an adjusting element (900; 905, 910) for adjusting the seal at the air intake channel, thereby regulating the level of foaming. 2. Mixing device according to claim 1, containing: a first container (110) containing a channel structure; and a second container (120) configured to receive the first container; wherein the seal (130) is located between the first container and the second container. 3. The mixing device according to claim 1 or 2, wherein the first container (110) includes a projecting channel portion (145), and wherein a channel structure is formed between the projecting channel portion and a seal (130). 4. Mixing device according to any one of paragraphs. 1-3, in which the adjusting element includes a pusher (905) for pushing the seal (130) into the air intake channel (725). 5. The mixing device according to claim 4, comprising an outlet nozzle (122) from which frothed milk is to be dispensed from the mixing chamber, wherein the adjustment member comprises an adjustment ring (910) around the outlet nozzle, wherein the adjustment ring operates a pusher (905 ), and the adjusting ring is rotatable to adjust the movement of the pusher towards the air intake channel. 6. The mixing device according to claim 5, wherein the adjusting ring (910) includes a curved surface (915) for actuating the pusher. 7. The mixing device according to any preceding paragraph, in which the adjusting element (900; 905, 910) has at least three positions containing: position for maximum foam level; position for intermediate foam level and position without foam formation. 8. The mixing device according to any preceding claim, wherein the seal (130) is a sealing seal. 9. Coffee maker containing: device for producing liquid coffee extract; mixing device according to any preceding claim and dispensing device configured to dispense: liquid coffee from a device for obtaining liquid coffee extract and frothed milk from the mixing device.