Abstract:
An appliance for preparing frothed milk includes a container for receiving milk and a docking element for connection to a drinks preparation machine. The docking element includes a connection for steam delivered by the drinks preparation machine, and a milk froth outlet for the frothed milk. The docking element includes a main body with a plurality of fluid channels and a supplementary part, which is reversibly removable from the main body. The supplementary part has a material that is softer in comparison to the main body, is continuous and includes several elements through which milk, steam, water and/or air can flow and which engage into the fluid channels.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0001]    The invention generally relates to the field of appliances for preparing drinks and, more particularly, toward an appliance for producing milk froth and milk drinks, to a drinks preparation system as well as to a drinks preparation machine. 
       Description of Related Art 
       [0002]    Milk frother appliances as integrated modules of coffee machines or as separate appliances, which are dockable onto coffee machines are known. EP 2 047 779 discloses a coffee machine with a dockable milk module, wherein hot steam from the coffee machine is used to froth milk which is sucked out of a vessel of the milk module according to the Venturi principle. The frothed milk is dispensed via a pivotable arm. EP 2 220 973 shows a coffee machine with a dispensing device for milk froth. The acting manner of the dispensing device is likewise based on the Venturi effect, on account of which milk is sucked out of a separate vessel by way of hot steam injected into the Venturi nozzle, is swirled with air and is thus frothed up. The dispensing device is integrated into the housing of the coffee outlet, but is arranged such that milk does not need to be led further into the inside of the coffee machine, so that its parts can be cleaned separately. Despite this, the principle is based on milk being processed in the inside of the coffee machine housing, which demands more effort on the part of the user for cleaning. 
       SUMMARY OF THE INVENTION 
       [0003]    An object of present invention is to provide an appliance for producing milk froth, which overcome disadvantages of the state of the art, is optimised for cooperating with an appliance for preparing hot drinks, in particular with a coffee machine, and in particular has advantages concerning a simple cleaning to be carried out by the user. 
         [0004]    The appliance for preparing frothed milk includes a container for receiving milk and a docking element for connection onto a drinks preparation machine, the docking element including:
       a connection for steam delivered from the drinks preparation machine;   a milk froth outlet for the frothed milk.       
 
         [0007]    Further, the docking element includes a main body with a plurality of fluid channels and a supplementary part that is reversibly removable from the main body, wherein the supplementary part has a material that is softer compared to the main body, is continuous and includes several elements, through which milk, steam, water and/or air can flow and which engage into the fluid channels. 
         [0008]    The supplementary part in particular can be constructed as one piece from an elastically and/or plastically deformable, comparatively soft material. “Deformable” here for example means that the material can be manually substantially deformed by the average user without aids and without an excessive force effort. 
         [0009]    The supplementary part can be designed, for example, as a silicone part. As is known per se, silicones are suitable for applications in the field of foodstuffs, since apart from their deformability, they can also be heated and are inert and can therefore be easily cleaned, for example also in a dishwasher. 
         [0010]    The supplementary part in particular can be arranged in a manner at least partly embracing the main body and can be unravelled from this. It can include an extensive or two-dimensionally-frame-like base and on this, the elements that can be subjected to through-flow. The base of this supplementary part is thereby laid around the main body in a folded and/or bent manner. 
         [0011]    Such a base of the supplementary part in particular can be formed from flat sections with joints that are arranged between the extensive (flattish) sections. Such joints can be formed by slots and/or recesses in the base and be designed as rotation joints (hinges) with only one degree of freedom. 
         [0012]    The directions, in which flow can pass through the different elements, can be different, for example by way of the elements being present at different sides of the main body. 
         [0013]    In embodiments, the supplementary part in particular is designed such that amongst others, it bears on two oppositely lying sides of the main body and includes, for example, elements of the mentioned type. 
         [0014]    In embodiments, at least one nozzle and/or a valve is/are amongst the elements, i.e. the supplementary part forms at least one nozzle and/or valve. The nozzle or the valve can project completely or partly into a fluid channel in the main body or include a collar projecting into such a channel. One example of a valve is a duckbill valve. 
         [0015]    Such elements in the form of a nozzle and/or a valve form narrowings on account of their function, and the part of the fluid channel behind such a narrowing is difficult to clean. However, a regular and thorough cleaning is important for elements that come into contact with milk. The approach according to the invention permits these elements to be removed and exposed in a simple manner for the cleaning, by way of the supplementary part being separated from the main body. Since the supplementary part includes the several elements, despite this they also remain integrally together for the cleaning, do not get lost and can be re-inserted in simple manner, and specifically without incorrect assemblies being possible. 
         [0016]    The main body can be manufactured, for example, of a plastic and be manufactured, for example, in the injection moulding method, but other materials and manufacturing methods, for example ceramic materials or stainless steel can also be considered. The main body can be of one piece, but this is not a necessity. The main body, for example, can be manufactured from a material block, wherein the fluid channels can be lined with a material that is different from the material of the material block. One moreover also does not rule out the through-flow elements of the supplementary part engaging so far into the respective fluid channels in the assembled condition, that these also form a lining of the fluid channels and at least regionally prevent a contact between the fluid and the main body. 
         [0017]    Apart from the advantage of the simple handling for the cleaning and for the reassembly after the cleaning has been effected, the approach also has the advantage of an efficient manufacturability. 
         [0018]    Moreover, a docking element of the type according to the invention renders possible a particularly compact coupling between the drinks preparation machine and the milk frother appliance and one that is practical and simple in its handling. Due to the fact that the docking element also includes the milk froth outlet, this outlet in particular can be situated very close to the drinks preparation machine, and can lie closely to the drinks outlet of this drinks preparation machine given a suitable design of this. The distance between the milk froth outlet and the drinks outlet in particular can be such that a drinking vessel of common dimensions—for example a coffee cup or a Latte-macchiato glass—can be placed below both these outlets. 
         [0019]    Typical drinking vessels for hot drinks with milk have a diameter of 6-8 cm or more. The drinks preparation system with the milk frother appliance and with the drinks preparation machine is preferably designed such that the distance between the hot drink outlet and the milk froth outlet is so small, that such a vessel can be filled with the hot drink and with the frothed milk in one and the same position. The distance between the hot drink outlet and the milk froth outlet is therefore preferably maximal 5 cm, in particular maximal 4 cm or maximal 3 cm. Here, what is meant by the distance is the horizontal distance, i.e. the distance of the exit points of the drink or the frothed milk, in a projection along the vertical onto a horizontal plane. For the milk frother appliance, this can mean that a distance between the milk froth outlet on the one hand and an end surface of the docking element on the other hand, the end surface including the connection for the steam and the electrical interface, is maximal 2.5 cm, in particular maximal 2 cm or maximal 1.5 cm 
         [0020]    The docking element, including the main body and the supplementary part, can form conduits for the milk and the steam, by way of the fluid channels. It can also include a housing additionally to the main body and the supplementary part. 
         [0021]    In a group of embodiments, the appliance includes an electrically operated drive unit for delivering and/or frothing the milk, for example a gear pump. In these embodiments, the docking element can also have an interface for electrical current, which is supplied by the drinks preparation machine, for operating the drive unit. 
         [0022]    Leads for the electrical current between such an interface and the drive unit then, for example, run on the housing, in the housing and/or between the housing and the body. 
         [0023]    The electrical current, which is supplied via the interface, serves for the drive of an active element of the milk frother appliance, in particular of a pump, for example of a gear pump and in particular of a pump as part of a milk frothing unit for the preparation also of cold milk froth. The gear pump at an inlet side is connected to a milk feed conduit and to an air feed, for the purpose of preparing frothed milk. 
         [0024]    The milk frothing unit can optionally be configured such that an operating parameter is adjusted in a manner depending on a measured value and/or operator input. What is meant by “adjusting” here is exerting an influence upon the at least one operating parameter of the milk frothing unit, which influences how this unit acts during an active milk frothing operation. The adjustability therefore is different to a mere “on/off”, as is known from the state of the art. The adjustability in particular is effected in a manner such that a parameter, which is specified by the user and/or specified by a control, has an influence on the characteristics and/or quantity of the produced milk froth. In particular, an adjustable operating parameter can be a speed of the gear pump or the fed air quantity (which can be regulated for example by a valve unit with an adjustable valve opening). 
         [0025]    In the assembled condition of the drinks preparation system, the docking element can run between the drinks preparation machine and a main part of the milk frother appliance, and specifically above the drinks outlet. An end surface of the docking element, for example, can be essentially vertical for being brought into contact with a corresponding portion of the drinks preparation machine. The docking element can have an essentially cylindrical shape with a horizontal cylinder axis perpendicular to an end surface and with an arbitrary, for example essentially rectangular cross section. 
         [0026]    The milk frother appliance, for example, includes a mixing nozzle, in which the steam is brought together with the milk and, for the preparation of warm frothed milk, for example, also with air. In embodiments, the docking element can include the mixing nozzle. In particular, the mixing nozzle can be arranged directly above the milk froth outlet, i.e. the frothed milk gets into the milk froth outlet directly from the mixing nozzle. 
         [0027]    In embodiments, the flow of the steam—which gets into the mixing nozzle from the steam connection—effects the sucking of air and the intermixing with milk fed to the mixing nozzle, in a manner known per se, by which means frothed milk can be produced, and this is warm on account of the heat released by the steam, wherein this heat is predominantly, but not exclusively, released to the milk as condensation heat. This suction effect can be based on Bernoulli&#39;s law (wherein the mixing nozzle can then be designed for example as a Venturi nozzle) and/or on impulse transmission, as is known per se in combination with so-called jet pumps. 
         [0028]    On account of this design, the docking element, which is described here, is also suitable for milk frothers which, differing from embodiments with electrically operated drive units, also do without a milk pump and can only froth in a steam-assisted manner. 
         [0029]    Additionally to the mentioned connection for the steam, the docking element can include a further connection for water, which is hot, for example, and/or for steam, which is/are delivered by the drinks preparation machine, the water or steam being able to be used for through-rinsing and for cleaning. A conduit traversing the docking element can be present coming from this connection for the cleaning water or for the cleaning steam. This conduit runs out, for example, into the milk frothing unit, and as the case may be serves for through-rinsing and, under certain circumstances, also for sterilising the gear pump including the feed conduits and outgoing conduits. 
         [0030]    In embodiments, the drinks preparation machine can also include an air delivery location, through which air can be delivered to the milk frother appliance, for example to its gear pump as the case may be, in a regulated manner. In such embodiments, the docking element can additionally include an air feed-through for the air that comes from the drinks preparation machine and that is to be delivered to the milk frothing unit. 
         [0031]    A drinks preparation system, apart from the appliance, also includes a drinks preparation machine, in particular coffee machine. Such a machine can be designed as a machine of the type often called “capsule machine”, with a brewing chamber for inserting a portion capsule with an extraction material and for brewing a hot drink (coffee or possibly tea or another hot drink) from this extraction material and water. However, it can also be designed, for example, as a bean-to-cup coffee machine with a mill mechanism or as a piston machine for receiving coffee powder. 
         [0032]    The drinks preparation machine, for example, includes a water container, a water pump and a water heater. A brewing chamber for preparing the hot drink from heated water by way of extraction from an extraction material is also present. 
         [0033]    The drinks preparation machine is designed such that the milk frother appliance can be docked onto it, by way of a steam delivery location and a machine-side electrical interface being present and being arranged relatively close to one another and such that the docking element can be docked by way of a single predefined movement or a movement procedure (without parts that are moved relative to one another). Depending on the design of the milk frother appliance, the drinks preparation machine can moreover include an air delivery location of the previously mentioned type, which is connected to the machine&#39;s internal valve unit, the unit in particular being electronically controlled. 
         [0034]    The docking location with the steam delivery location and with the machine-side electrical interface (and air delivery location as the case may be) in particular can be present in the direct proximity of the drinks outlet. A distance between the drinks outlet and an end surface of the docking location, on which surface the respective end surface of the docked docking element abuts, can for example likewise be maximal 2.5 cm, maximal 2 cm or maximal 1.5 cm. 
         [0035]    A drinks preparation machine often has a front with a placement platform that projects from the front and is for drinks vessel, and above this, likewise projecting from the front, with a drinks outlet hood, on whose lower side the drinks outlet is arranged. In embodiments, the docking location is then present laterally on the drinks outlet hood. This, for example, means that the milk frother appliance is coupled onto the drinks outlet hood from the side. 
         [0036]    At least the docking element and, for example, the complete milk frother appliance is then arranged in front of the front of the drinks preparation machine, in the coupled-on condition. 
         [0037]    The milk frother appliance as well as a drinks preparation machine of the drinks preparation system, with regard to their dimensioning are matched to one another such that the milk frother appliance is either placed on the same level as the machine, or on a milk frother platform formed by the machine. Moreover, the milk frother appliance as well as the drinks preparation machine can be matched to one another with regard to their fashioning. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    Embodiment examples of the invention are hereinafter described by way of figures. The same or analogous elements are indicated in the figures by the same reference numerals. There are shown in: 
           [0039]      FIG. 1  is a view of the appliance for preparing frothed milk (milk frother appliance); 
           [0040]      FIG. 2  is an exploded representation of the milk frother appliance; 
           [0041]      FIG. 3  is an exploded representation of the milk frothing unit of the milk frother appliance; 
           [0042]      FIG. 4  is a view of the milk frothing unit sectioned along a horizontal plane; 
           [0043]      FIG. 5  is a partial view of the seal of the milk frothing unit with elements of the gear pump; 
           [0044]      FIG. 6  is a view of the upper main housing part of the milk frothing unit, which is sectioned along a horizontal plane; 
           [0045]      FIG. 7  is a view of the upper main housing part from below; 
           [0046]      FIG. 8  is a view of the upper main housing part, which is sectioned along a vertical plane; 
           [0047]      FIG. 9  is a view of the valve unit of the milk frothing unit; 
           [0048]      FIG. 10  is an exploded representation of the valve unit; 
           [0049]      FIGS. 11 a -11 c    are the valve unit in a plan view, side elevation and front elevation, respectively; 
           [0050]      FIG. 12  is a view of the milk frothing unit with a valve unit, from above; 
           [0051]      FIG. 13  is a representation of the milk frothing unit, sectioned along a plane through the valve unit; 
           [0052]      FIGS. 14 a -14 b    are views of the docking element, obliquely from above and below, respectively; 
           [0053]      FIGS. 15 a -15 b    are views of the supplementary part; 
           [0054]      FIGS. 16 a -16 b    are views of the main body; 
           [0055]      FIGS. 17 a -17 b    are representations of the docking element without an external housing; 
           [0056]      FIGS. 18 a -18 c    are representations of parts of the appliance, from which the function of the docking element is evident; 
           [0057]      FIG. 19  is a view of the drinks preparation system with the milk frothing appliance; 
           [0058]      FIG. 20  is a detail of the drinks preparation system, represented sectioned along a vertical plane; 
           [0059]      FIG. 21  is a detail concerning the docking of milk frothing appliance onto the drinks preparation machine; 
           [0060]      FIG. 22  is a view of a detail of the milk frother appliance; 
           [0061]      FIG. 23  is a schematic diagram of the drinks preparation system; 
           [0062]      FIG. 24  is a sectioned representation of the milk frother appliance, which is drawn only partly, with the docking element, in an alternative embodiment; and 
           [0063]      FIG. 25  is a view of this milk frother appliance in the alternative embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0064]    The appliance  1  for preparing frothed milk (milk frother appliance) is represented as a whole in  FIG. 1 .  FIG. 2  shows an exploded representation of its parts. 
         [0065]    The appliance  1  includes a milk container  3 , a milk frothing unit  5  and a lid  6 . 
         [0066]    The milk container  3  is designed in a doubled walled manner in the represented embodiment, for thermal insulation purposes, but single-walled designs are also possible. It can be transparent or include a viewing window for checking the level of the milk. 
         [0067]    The milk container  3  and lid  6  can be matched to one another such that the lid  6  can also be placed directly onto the milk container  3 , without the milk frothing unit  5  being arranged therebetween, by which means the filled milk container with the lid can be placed into the fridge for example. The milk container and the lid can also be cleaned in a simple manner, and be designed, for example, in a dishwasher-safe manner. 
         [0068]    The elements of the milk frothing unit  5  are represented in an exploded representation in  FIG. 3 . A lower main housing part  11  carries an electric motor  13  belonging to the gear pump, as well as an upper main housing part  14 . A lateral window  12  is formed in the upper main housing part. 
         [0069]    The upper main housing part  14  forms a roughly circularly cylindrical trough, in which gears  17  of a gear pump are arranged. The gears  17  of the gear pump are driven via a shaft  19 , which is connected to the electric motor  13 . A seal  21  seals the trough to the bottom. 
         [0070]    Additionally to the gears, the shaft and the electric motor, the gear pump can also have its own housing, or such can be integrated into the main housing or other parts, for example into a milk frothing unit cover  16 . In the represented embodiment example, the milk frothing unit cover  16  is shaped out such that a pump chamber encompassing the gears  17  is formed between the seal  21  and the milk frothing unit cover  16 , on account of an arching  15  (also clearly visible in  FIG. 12 ). 
         [0071]    A valve unit  20  is also fastened on the main housing  11 ,  14 . 
         [0072]    A milk suction tube  18  (not represented in  FIG. 3 ) extends downwards from the plane of the gear pump and projects into the milk container  3  and almost up to the base of this, in the assembled condition of the appliance  1 . 
         [0073]    A connection shaped part  22  is further present beneath the gear pump. This part seals the window  12  and simultaneously forms a feed-through for connection of conduits of the milk frother which are described hereinafter and are fastened on the one hand to the main housing, and on the other hand to a docking element. 
         [0074]    Likewise visible in  FIG. 3  are a spacer  23  and a motor seal element  24 . 
         [0075]    The docking element includes a docking element body, which is protected by a docking element housing  26 . The docking element body is formed by a main body  25  and a supplementary part  27 , which is described in yet more detail hereinafter. It can already be seen in  FIG. 3  that the supplementary part  27  includes a downwardly projecting milk froth outlet  28 . 
         [0076]      FIG. 4  shows a view from above, of the milk frothing unit  5 , which is sectioned along a plane lying above the sealing plane defined by the seal  21 . The lighter lines in the plan view represent elements running further below, which per se are not visible. 
         [0077]    The gear pump is attached above the sealing plane. An upper-side liquid conduit  31  leads to the gear pump. This is connected on the one hand to the milk suction tube  18  and on the other hand to a hot water conduit and/or steam feed conduit  32 , via duckbill valves  42 ,  41 , which are formed by the seal  21  and are also clearly visible in  FIG. 5 . An air feed conduit  34  is connected to the upper-side liquid conduit, which is to say to the gear pump at the inlet side, likewise via a duckbill valve  43 , which is formed by the seal. 
         [0078]    Arranged behind the gear pump is a feed-through  36  for the delivered milk that is already frothed, depending on the selected operating condition, through which feed-through this milk again goes downwards through the sealing plane, where it gets through an outgoing conduit  35  into the docking element. 
         [0079]      FIGS. 6 to 8  show further views of the upper main housing part  14 , which in represented sectioned along a horizontal plane in  FIG. 6  and along a vertical plane in  FIG. 8  and in a view from below in  FIG. 7 . 
         [0080]    The lower-side conduits are formed by tubes of the connection shaped part  22 , which are laid into corresponding channels of the upper main housing part  14 . These channels, i.e. the channel  51  for the hot water and/or steam feed conduit  32 , the channel  52  for the air feed conduit  34  and the channel  53  for the outgoing conduit  35  are particularly clearly visible in the view from below according to  FIG. 7 . 
         [0081]    The seal  21  ( FIG. 8 ) is clamped between the upper main housing part  14  and the milk frothing unit cover (not shown in  FIG. 8 ). The pump chamber of the gear pump including the gears  17  is formed between the milk frothing unit cover and the upper main housing part, due to the arching  15  in the milk frothing unit cover ( FIG. 3 ;  FIG. 12 ). 
         [0082]    A further optional feature can be seen in  FIG. 8 . The feed-through  36  for the delivered milk, which is already frothed depending on the selected operating condition, is narrowed in the manner of a throttle. A certain backpressure is produced in the gear pump by way of this, on account of which pressure the flow quantity regulates itself. This backpressure contributes to an efficient frothing of the cold milk. 
         [0083]      FIG. 9  shows a view of the valve element  20 ,  FIG. 10  shows an exploded representation of the valve unit and  FIGS. 11 a -11 c    show the valve unit in a view from above, sectioned along the line E-E in  FIG. 11 a    and along the line D-D in  FIG. 11   a.    
         [0084]      FIG. 12  shows a view of the milk frothing unit with a valve unit  20 , without the docking element and milk suction tube, from above, and  FIG. 13  shows this sectioned along a vertical plane going through the line  213  in  FIG. 12 . 
         [0085]    The valve unit  20  has two valve elements in a common valve housing  61 . Each valve element has a closure element  62 , which carries a sealing element  63  and is movable along an axis—in the selected installation situation—along the vertical axis. The upward movement is effected by way of an electromagnet  64  and against the force of a spring  65  stressed between the electromagnet (or the valve housing) and a securing ring  66 . The heads of the valve elements, which are formed at the upper side by the closure elements and seal elements, project through openings in the upper main housing part  14  (see  FIGS. 12 and 13 ). In the closed condition, a seal portion  67  of the respective seal element  63  is pressed by the force of the spring against a surface of the upper main housing part  14 , along the periphery of the respective opening. 
         [0086]    With both valves, a valve chamber  71  forms in each case between the respective wall of the upper main housing part  14  and a seal  68 . An inflow opening forms when the closure element with the sealing element  63  is lifted by the electromagnet, through which inflow opening air can flow from the outside into the respective valve chamber  71  and from this can get into a (common) air feed conduit through an air connection stub or branch  73 . 
         [0087]    The two valve elements can be actuated independently of one another and can be opened in each case individually or together. Different valve opening conditions can be created by way of this. As a whole, four valve opening conditions result by way of either only one of the valve elements being open and the other closed, both being open or both being closed. 
         [0088]    In embodiments, it can also be meaningful for the valve elements and/or the size of the respectively formed inflow opening to be selected to a differently large extent and/or for the air that is admitted by one of the valve elements to be subjected to a significantly greater flow resistance than the air admitted by the other valve element. The four different defined opening conditions are then quantitatively different. For example, the inflow opening of one of the valve elements can be double the size of the inflow opening of the other valve element, so that the conditions “0” (air valve completely closed), “⅓” (the smaller valve element open), “⅔” (the larger valve element open) and “1” (both valve elements open) can be selected. 
         [0089]    An airflow regulating element such a 3/2-way valve, for example, (not shown) and by way of which the path between the valve chambers  71  and the mixing nozzle or the path between the valve chambers and the entry of the gear pump can be opened and the respective other path can be closed, can be arranged in a manner connected downstream of the valve unit in the airflow direction, in order to regulate whether the mixing nozzle or the gear pump is to be fed with air. Such an airflow regulating element however can also be done away with, wherein the regulation is then effected automatically by the respective valve elements, by way of these only opening due to a vacuum at the outlet side, and in this manner preventing a backflow of frothed milk into the respective path, which is not required. 
         [0090]    The construction and manner of action of the docking element are described hereinafter by way of  FIGS. 14 a   - 14   c.    FIGS. 14 a  and 14 b    show views of the docking element obliquely from above and obliquely from below respectively.  FIGS. 15 a  and 15 b    show the supplementary part  27  in an unfolded condition and  FIGS. 15 c  and 15 d    in a folded condition.  FIGS. 16 a  and 16 b    show the main body  25 .  FIGS. 17 a , 17 b  and 17 c    show the docking element sectioned along the planes A-A, B-B and C-C in  FIG. 17   d.    FIG. 18 a    shows a view of the appliance from above, and  FIGS. 18 b  and 18 c    show sections of sectioned representations of the appliance sectioned along the planes A-A and B-B in  FIG. 18 a   , respectively. 
         [0091]    The face-side end, which, for example, lies at the front in  FIGS. 14 a    and  15   c,  is coupled onto the coffee machined on operation, whereas the opposite end can be coupled onto the milk frothing unit  5 . 
         [0092]    The main body  25  as a whole can be designed as a shaped body of a suitable, heat-resistant plastic and be manufactured for example as an injection moulded part. The supplementary part  27  is manufactured from silicone, for example. It is of one piece and as a whole is designed in an extensive (sheet-like) manner with functional elements, which are integrally formed thereon. The entirety of the extensive sections is here indicated as a “base”. Joints  81 , which are formed by continuous openings as well as groove-like recesses and which permit an unconstrained folding around the main body  25 , are formed between the extensive sections  80 . The dimensions of the extensive sections  80  between the grooves are matched to the dimensions of the main body. 
         [0093]    Apart from the milk froth outlet  28 , the functional elements of the supplementary part  27  are formed by feed-throughs  82 - 86 , and a mixing nozzle element  89 . 
         [0094]    The main body  25  forms a feed-through conduit  96 , which passes from the end at the coffee machine side to the opposite end and which is for cleaning water (cold or heated by the coffee machine) or cleaning steam, the water or steam when required going from the feed-through conduit  96  into the hot water and/or steam feed conduit  32  and from this into the elements to be cleaned, in particular the gear pump. A feed-through  86   84  of the supplementary part is assigned to the feed-through conduit  96  in each case at the coffee machine side and the milk frother side. 
         [0095]    A steam connection, through which steam gets from the coffee machine into the mixing nozzle, is also formed. The steam connection is formed by a feed-through  85  with an assigned valve  87  of the supplementary part  27 , the feed-through projecting into a steam connection opening  95  of the main body  25 . 
         [0096]    On the milk frother side, an opening  92 ,  93  for the supply of air and milk and into which corresponding feed-throughs  82 ,  83  of the supplementary part project are formed in the main body in each case. The air feed-through  82  is provided with an assigned valve  88 , and this is designed as a duckbill valve just as the steam valve  87  and is of one piece with the remainder of the supplementary part  27 . 
         [0097]    For the mixing nozzle, the main body  25  includes a mixing nozzle opening  99 , into which the mixing nozzle element  89  projects. A milk froth outlet continuation  91  and a positioning ring  94  surrounding this are moreover formed on the underside and cooperate with a corresponding structure  90  of the supplementary part. 
         [0098]    The mixing nozzle is formed between the mixing nozzle element and correspondingly shaped chambers of the main body  25 . 
         [0099]    Steam, which is fed in via the steam connection, via the valve  87  gets into a mixing nozzle chamber  97 , which one can see particularly well in  FIG. 17 c   , for example. A vacuum is produced in the mixing nozzle chamber  97  by way of the flow of steam, by way of which vacuum air and milk is sucked via the respective feed-throughs  82 ,  83  ( FIG. 17 b   ,  FIG. 18 b   ). Milk froth arises in the mixing nozzle chamber, and goes downwards through the milk froth outlet  28  and into a ready-and-waiting drinks vessel. The frothed milk is warm due to the condensation heat released by the steam. 
         [0100]    On account of the small nozzle opening, through which the steam exits at a high speed, the mixing nozzle is thus designed such that a vacuum is produced due to the nozzle effect. This also assists the transport of milk out of the milk conduit, even if the milk is actively delivered due to the gear pump. 
         [0101]    The duckbill valves  87 ,  88  are closed if normal pressure or a slight overpressure prevails in the inside of the mixing nozzle chamber  97 . However, they both automatically open if in contrast—as soon as steam flows in—a vacuum prevails on account of the Bernoulli effect and/or on account of impulse transmission. 
         [0102]    The feed of air into the mixing nozzle chamber can also be effected directly from the outside, for example via a duckbill valve, instead of through the valve unit, wherein two air paths that are independent of one another then result, on the one hand for the mixing nozzle chamber and on the other hand for the gear pump. 
         [0103]    Such a design with the feed of air directly into the mixing nozzle chamber can also be selected for embodiments, for example, with which, differing from the example described here, no electrically operated drive means (no electrically operated pump) is present and with which one froths merely in a steam-assisted manner, whilst utilising the suction effect of the mixing nozzle. 
         [0104]    The docking element is designed such that the milk froth outlet  28  can lie closely to the outlet for the hot drink. For this purpose, it is arranged in the direct proximity of the end surface  29  coupled to a corresponding surface of the drinks preparation machine. As discussed previously, the distance is not more than 2.5 cm and is preferably even less. The distance as usual is measured as the distance that is measured perpendicularly to the (vertical) plane defined by the end surface, between this plane and the center point of the exit opening out of the milk froth outlet. 
         [0105]    A further optional feature is particularly clearly evident in  FIG. 17   c.  The outlet chamber  86 , through which the—generally frothed—milk runs downwards, tapers in the milk froth outlet  28 . This on the one hand has an additional froth-forming and froth-homogenising effect and on the other hand channelises the flow of milk or milk froth. 
         [0106]      FIG. 19  shows a view of the complete drinks preparation system  100  with the milk frothing appliance  1  and a coffee machine  101 , onto which the milk frothing appliance  1  is coupled.  FIG. 20  shows a detail concerning this appliance, with the outlet hood represented in a sectioned manner. 
         [0107]    The coffee machine, as is known per se for coffee machines, comprises a water container, a water pump and a water heater. A brewing chamber for preparing coffee from heated water by way of extraction from coffee power is moreover present, the coffee powder being provided, for example, in portion capsules that were previously inserted into the coffee machine before the preparation. As an alternative to a portion capsule system, the coffee machine can also be designed as a so called bean-to-cup coffee machine that includes a coffee mill and grinds the coffer powder in a portioned manner and feeds it to the brewing chamber. As yet a further alternative, particularly if the coffee machine is designed as a piston machine, i.e. the brewing chamber is formed between a fixed part and a removable piston, one can yet also envisage the coffee power being brought into the brewing chamber by the user in a manner in which it is already in the ground, but loose (non-compacted) condition. 
         [0108]    The coffee machine can further include a capture container for spent coffee powder portions (in capsules or in a loose manner, depending on the design of the coffee machine). 
         [0109]    A placement platform  103  for placing a drinks vessel or cup is formed on the coffee machine. This can be formed, for example, by way of a grating, below which a capture dish is located. In embodiments, the placement platform can be height-adjustable in a suitable manner. 
         [0110]    A coffee outlet  105 , through which brewed coffee runs out and gets into the cup or vessel lying therebelow, is located above the placement platform  103 . This outlet is located below an outlet hood  108 , which forms part of the coffee machine housing and at least partly covers the outlet to the front and to the sides. 
         [0111]    The coffee machine  101  forms a front  106 , from which, as is known per se from other coffee machines, on the one hand the placement platform  103  projects and on the other hand, above this, the outlet hood  108  projects. 
         [0112]    Here, a milk frother platform  107 , onto which the docked milk frothing appliance  1  is placed, likewise projects from the front. 
         [0113]    A connection location  110  for the connection of the docking element onto the coffee machine is located in the proximity of the coffee outlet  105  and here, below the outlet hood. This connection location includes a steam delivery location  111  for coupling onto the steam connection of the docking element, and a hot water and/or steam delivery location  112  for coupling onto the feed-through conduit  83 . The steam delivery location  111  and the hot water and/or steam delivery location  112  when required are respectively supplied with steam and hot water from the water heater, wherein a multi-way valve in the inside of the coffee machine can selectively feed heated liquid or steam to the brewing module, the steam delivery location or the hot water and/or steam delivery location  112 . 
         [0114]    The connection location further preferably includes electrical contacts  113 , which are represented schematically in  FIG. 21 . These electrical contacts  113  form an interface on the drinks preparation machine side, and, given a coupled-on docking element, create an electrical connection to corresponding electrical connection element contacts that are connected to electrical leads leading through the docking element or are formed by these. These electrical leads supply the electrically driven elements of the milk frother appliance, specifically the gear pump, with electricity and control signals as the case may be. 
         [0115]    Thereby, it is possible to provide a control of these electrically driven elements in the milk frother appliance (this appliance is then provided with the necessary electronic units and receives control signals from the coffee machine or from an input unit of the milk frother appliance) as well as to accommodate a control of these elements in the coffee machine itself. In the latter case, it is essentially only currents driving the electrically driven elements in accordance with the settings of the control that are led through the electrical leads. 
         [0116]    The docking of the milk frother appliance  1  is effected from the side onto the outlet hood  108 , and specifically such that the milk frother appliance as a whole is arranged in front of the coffee machine and laterally of the outlet hood  108 . The docking is effected, for example, by way of a simple, linear, lateral movement of the assembled milk frother appliance along the front  106 . 
         [0117]    As one can see in  FIG. 21  (showing the milk frother appliance  1  in a decoupled condition) and in particular in  FIG. 22  (milk frother appliance without a coffee machine), the electrical leads and the corresponding contacts  98  on the docking element side are formed on the docking element housing  26 . The leads can be formed by way of insulated wires or strand conductors or by way of strip conductors of printed circuit (circuit board or flexprint) or the like. 
         [0118]    The control of the gear pump in particular is configured such that the speed of the gears  17  can be adjusted, i.e. is selectable. By way of this, the user can control the delivery speed and—according the procedure which is described in more detail hereafter—as the case may be the preparation of cold frothed milk. 
         [0119]      FIG. 23  shows an overview diagram of the milk frother appliance and its coupling onto the drinks preparation machine (coffee machine  101 ). Air feeds are indicated as “L” in the figure. The letter D indicates a conduit for steam, K a conduit for the hot drink, R a conduit for cleaning water or steam (optional) and S indicates the electricity supply. 
         [0120]    The activation  195  here is represented as part of an electronics unit  121  of the coffee machine  101 . The electronics unit  121  is configured, for example, to recognise a capsule by way of a measurement and/or to accept a user input, for example, via a suitable operating element with a corresponding button, with a touchscreen and/or the like. 
         [0121]    Here, the activation  195  is designed such that it can activate the gear pump  7  as well as the valve unit  20 , wherein an operating parameter of the gear and/or of the valve unit can be regulated (closed-loop controlled). Activation signals for the valve unit  20  and/or for the gear pump  7  run directly via the connection location  110 . 
         [0122]    An activation  195 ′ can also be present completely or partly as part of the milk frother appliance, alternatively to incorporating the activation completely or partly in the coffee machine. This alternative is represented in  FIG. 20  in a dashed manner. The electrical energy and, as the case may be, data signals can then be transmitted from the electronics unit to the activation  195 ′ via the alternative interface  110 ′. 
         [0123]    The mixing nozzle is indicated as a whole by the reference numeral  79 . 
         [0124]    The milk frother appliance can be operated in the manner described hereinafter. 
         [0125]    The gear pump is set in motion whilst at least one of the valve elements of the valve unit  20  is open, for the preparation of cold frothed milk. A vacuum is produced at the inlet side of the gear pump due to the effect of this pump, and this vacuum sucks or draws milk through the milk suction tube  18  and the corresponding duckbill valve  42 , as well as air through the valve unit  20  and the corresponding duckbill valve  43 . Milk froth therefore arises in the gear pump and gets through the feed-through  36 —whose narrowness encourages the formation of fine-pored froth—, the outgoing conduit and the docking element  25 , to the milk froth outlet  28  and is dispensed there, wherein generally is drinks vessel  200  is placed upon the platform  103 . 
         [0126]    The drawing of the generally cold milk out of the milk container  3  via the gear pump is also effected for the preparation of warm frothed milk. This gear pump delivers the milk into the mixing nozzle. Steam from the coffee machine is simultaneously fed to this nozzle via the steam connection. As has already been explained above, the steam produces a vacuum that, on the one hand, exerts an additional suction upon the milk and assists in the delivery through the gear pump and, on the other hand, sucks or draws air through the likewise at least partly open valve element  20 . In the mixing nozzle chamber  97 , the milk is mixed with the steam, which heats it up and air is simultaneously intermixed, so that small air bubbles form and milk froth arises. The warm, frothed milk is dispensed through the milk froth outlet. 
         [0127]    As mentioned and depending on the situation, a 3/2-way valve or another means can selectively connect the valve element  20  to the gear pump  7  or to the mixing nozzle chamber  97 , for the production of cold and warm milk froth respectively. As mentioned, it is also possible for the air feed into the mixing nozzle chamber not to be effected via the valve element  20  but in a direct manner, in which case the supply of air cannot then be regulated by way of a separate means when producing warm milk froth. 
         [0128]    One can also envisage the user also only being able to deliver cold milk. In this case, the gear pump is driven, but the valve elements remain closed, and also no steam is fed. 
         [0129]    One can also envisage the user being able to prepare warm milk. In this case, the valve element, through which air can get into the mixing chamber, is closed. Should a separate valve for the mixing nozzle chamber be provided (differing from the embodiment represented in the figures), then there is also the possibility of designing the respective valve in a closable manner. A closure of the valve can also be envisaged mechanically by the user by hand for example. For preparing warm milk, the milk is delivered out of the milk container  3  by way of the gear pump, and steam is simultaneously fed in the mixing nozzle  79 , without air also being fed. Warm milk arises due to the mixing of the cold milk with the steam, and this is then dispensed via the milk froth outlet  28 . 
         [0130]    For on-the-spot cleaning, a vessel is placed below the milk froth outlet  28 , and warm water or steam is fed through the feed-through conduit  96  and the hot water and/or steam feed conduit  32 . The gear pump is simultaneously set in motion. 
         [0131]    The milk frother appliance, however, is also very simple to clean after it has been removed. The milk container  3  and the lid  6  can be designed in a dishwasher-safe manner without any problems. The milk frothing unit  5  can likewise be simple taken part and cleaned, wherein it is quite useful for the seal  21  to be designed as one piece with the duckbill valves  41 ,  42 ,  43  and for it to terminate with the surface of the upper main housing part  14  in a flush manner. 
         [0132]    Finally, the docking element is simple to clean due to the fact that the parts that come into contact with milk (main body  25 , supplementary part  27 ) can be simply dismantled, designed in a dishwasher-safe manner and also be simple assembled again in only a single—correct—configuration. 
         [0133]      FIGS. 24 and 25  represent an alternative embodiment. This differs from the embodiment described above, in that the supply of air towards the air feed of the gear pump—thus for example to an air feed conduit  34 , for example of the described type, or directly to the pump chamber—is not effected by a valve unit belonging to the milk frother appliance, but in a manner coming from the drinks preparation machine. The drinks preparation machine includes, for example, an electronically regulated valve unit for this purpose. This valve unit can be based essentially on the same functioning principle as the valve unit of the milk frother appliance, which is described above. It can alternately have a different functioning principle, for example by way of it only having one valve unit. 
         [0134]    For this purpose, the docking element includes an air connection  151  towards the drinks preparation machine. Air gets through an air feed-through  152 , which here horizontally passes through the docking element, into the milk frothing unit. In the represented embodiment example, a section of the air feed-through is formed by a tube portion  155  of the docking element housing  26 , which however is not a necessity (concerning the air feed-through, a regular cleaning is not a necessity, in contrast to conduits, through which milk flows). 
         [0135]    The possibility of the electrical contacts being able to be formed by a contact module  160  is yet indicated in  FIG. 25 , wherein this module, for example, can include a circuit board or the like and be insertable into a suitable recess in the docking element housing  26   
         [0136]    The valve unit arranged in the milk frothing unit is done away with in the embodiment according to  FIGS. 24 and 25 . 
         [0137]    Many further variants are conceivable. Apart from the options that have already been discussed, there is also the possibility of keeping the conduits for cold milk froth (from the pump) and for warm milk froth (created in the mixing nozzle) separate from one another up to the outlet, i.e. the cold milk froth is then not led through the mixing nozzle. The milk froth outlet can then include openings that are separate from one another, for example concentric to one another, for the cold and the warm milk froth. Milk froth outlets for the cold and the warm milk froth and which are completely separate from one another are also conceivable, and the optional conditions for the maximal distance between the milk froth outlet and the hot drinks outlet, which are discussed above apply in this case, for example, for the discharge of the warm milk froth, since it is often this milk froth which is mixed with the hot drink. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           1  milk frother appliance 
           3  milk container 
           5  milk frothing unit 
           6  lid 
           7  gear pump 
           11  lower main housing part 
           12  window 
           13  electric motor 
           14  upper main housing part 
           15  arching (in the milk frothing unit cover) 
           16  milk frothing unit cover 
           17  gears 
           18  milk suction tube 
           19  shaft 
           20  valve unit 
           21  seal 
           22  connection shaped part 
           23  spacer 
           24  motor seal element 
           25  main body (of the docking element) 
           26  docking element housing 
           27  supplementary part 
           28  milk froth outlet 
           29  end surface 
           31  liquid conduit 
           32  hot water and/or steam feed conduit 
           34  air feed conduit 
           35  outgoing conduit 
           36  feed-through 
           41  duckbill valve 
           42  duckbill valve 
           43  duckbill valve 
           51  channel for hot water and/or steam feed conduit 
           52  channel for air feed conduit 
           53  channel for outgoing conduit 
           61  valve housing 
           62  closure element 
           63  seal element 
           64  electromagnet 
           65  spring 
           66  securing ring 
           67  sealing portion 
           68  seal 
           71  valve chamber 
           73  air connection stub 
           79  mixing nozzle 
           80  extensive sections 
           81  joint 
           82  air feed-through 
           83  feed-through (for milk) 
           84  feed-through for hot water or steam 
           85  feed-through for steam 
           86  feed-through for hot water or steam 
           87  duckbill valve 
           88  duckbill valve 
           89  mixing nozzle element 
           90  ring (structure) for positioning ring 
           91  milk froth outlet continuation 
           92  opening for the air feed 
           93  opening for the milk feed 
           94  positioning ring 
           95  steam connection opening 
           96  feed-through conduit 
           97  mixing nozzle chamber 
           98  (electrical) contacts 
           99  mixing nozzle opening 
           100  drinks preparation system 
           101  coffee machine 
           103  placement platform 
           105  coffee outlet 
           106  front 
           107  milk frother platform 
           108  outlet hood 
           110  connection location 
           110 ′ alternative interface 
           111  steam delivery location 
           112  hot water and/or steam delivery location 
           113  electric contacts 
           121  electronics unit 
           151  air connection 
           152  air feed-through 
           155  tube portion 
           195  activation 
           195 ′ alternative activation 
           200  drinks vessel