Abstract:
A steam automatic dispensing device for preparing hot and/or frothed drinks, includes a first duct ( 13 ) for introducing steam inside a drink; a second duct ( 15 ) for introducing air inside the drink; an electronic control unit ( 51 ) for controlling the introduction of steam and/or air through said first and second duct, the control unit being programmable to carry out a predetermined control cycle depending on the desired drink to be obtained and on the drink temperature.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     A. Field  
         [0002]     The present invention refers to a steam automatic dispensing device for preparing hot and/or frothed drinks.  
         [0003]     B. Related Technology  
         [0004]     Preferably, but not exclusively, the invention is employed as an accessory separated or integrated of the espresso coffee machine for bar, for producing frothed hot milk to be used for instance for preparing cappuccinos.  
         [0005]     It is known that, for producing milk froth with espresso coffee machines, the operator uses a container within which he pours a certain amount of milk, inside which he introduced steam through a jet simultaneously shaking the container, so to generate a certain turbulence inside the milk and to add in the environment air needed for producing froth.  
         [0006]     The qualities and the quantity of the produced froth depend on the way the milk is shaken and on the amount of steam introduced, and they are therefore linked to the sensibility and experience of each operator. It follows that such features, and then the ones of the cappuccino within which the frothed milk is used, vary from operator to operator and they can be completely unsatisfactory to the client even deemed to be excellent by the operator.  
         [0007]     A solution to the problem of how making the quality of the obtained product independent from the operator is the subject of the international patent application WO 01/97668, in the name of the applicant. Such patent application discloses a device essentially consisting of a container within which milk to be heated and to be frothed can be poured, inside which are provided a first duct for introducing steam in milk and a second duct, joined to said first duct, for introducing in milk the air needed for producing froth. The duct for steam dispensing is provided with a radial opening for the exit of steam and the duct for air ends within an axial opening placed in front of said radial opening of the steam duct. This way, the steam dispensing from said radial opening produces a depression that in its turn causes the air suction through the corresponding duct, the steam effusion velocity generates a turbulence at the bottom of milk causing that it is heated and mixed with air and a milk-air-steam mixture is therefore produced directly inside milk, with consequent froth formation.  
         [0008]     However effective, the device above illustrated proves to be not much versatile, because it always provides the production of a milk-air-steam mixture and it makes impossible, for instance, the production of hot milk without froth.  
         [0009]     Other devices using steam for heating drinks or food are respectively described in the documents U.S. Pat. No. 6,099,878 and FR 2 824 249.  
         [0010]     U.S. Pat. No. 6,099,878 discloses a fully automatic, milk inclusive espresso coffee machine which includes coffee bean grinding and brewing apparatus and a milk aeration system which pumps a selection of milk from an internal refrigerator through a choice of aeration processes to a steaming apparatus for heating and further conditioning the milk for joining the brewed coffee liquor. With each beverage production cycle all milk is hygienically either served or returned to its refrigerated reservoir. A process is disclosed which includes pumping milk, all in a refrigerated environment, selectively along a plurality of milk lines one of which may inject air for foaming the milk to a steam delivery line for heating and steaming it and delivering it to a beverage cup. After the desired amount of milk has been delivered, the steam flow continues momentarily to cleanse the line of residual milk. FR 2 824 249 discloses a device for heating food comprising a temperature measurement rod including an agitator section with steam outlets and temperature sensor. A handle is used for stirring. The steam generator feeds the outlets through a flexible tube connected to the rod. An electrical controller is wired to the sensor and steam generator and/or a display unit.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     It is the main object of the present invention to realise a device for heating and/or preparing froth of a liquid that allows to automatically obtain different kinds of drinks, such as for instance, hot milk, hot and frothed milk, infusions, etc.  
         [0012]     Another object of the present invention is to realise a device for heating and/or preparing froth of a liquid having limited size, that can be easily used in association with a professional coffee machine.  
         [0013]     A further object of the present invention is to realise a device for heating and/or preparing froth of a liquid that allows to control the temperature of the liquid to be heated.  
         [0014]     These and other objects are achieved with the automatic device for heating and/or preparing froth of a liquid as claimed in the accompanying claims.  
         [0015]     By following the teachings of WO 01/97668, the device according to the invention comprises a first duct to introduce steam and a second duct through which it is possible to introduce air inside a liquid to be heated in order to obtain the formation of froth.  
         [0016]     Advantageously, according to the present invention, each of said ducts is connected to an electrovalve: the user can select the kind of wanted drink and, on the basis of said selection, a microprocessor controls the opening and the closing of said electrovalves, so to permit or prevent according to a preset cycle the introduction of air and steam in the drink.  
         [0017]     Said microprocessor can be equipped with a storage within which a plurality of operating cycles are stored, corresponding to a plurality of drinks that can be prepared with said device. Each of said operating cycles provides a sequence of steps of preset duration of opening and closing of each valve.  
         [0018]     Advantageously, the device according to the invention can further comprise a sensor for measuring the temperature, so to control the temperature of the liquid to be heated and/or frothed and, in case, to correct the parameters of the above-mentioned operating cycles in order to obtain a drink at the desired temperature. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0019]     A preferred embodiment of the invention will be now described in detail with particular reference to the attached drawings, supplied as non limiting example, in which:  
         [0020]      FIG. 1  is a schematic side view of the ducts dispensing steam and air of the device according to the invention;  
         [0021]      FIG. 2   a  is a scheme of a first embodiment of the device according to the invention;  
         [0022]      FIG. 2   b  is a scheme of a second embodiment of the device according to the invention;  
         [0023]      FIG. 3  is a block diagram of the electronic control unit of the device according to the invention;  
         [0024]      FIG. 4  is a graph showing the opening and closing steps of the valves in an example of preparing cycle of a drink. 
     
    
     DETAILED DESCRIPTION  
       [0025]     With reference to  FIG. 1 , an embodiment of the device according to the invention is shown that comprises a first duct  13  for steam and a second duct  15  for air. In the example shown said ducts are immersed into the liquid, for instance milk, contained inside a container  11 .  
         [0026]     The steam duct  13  has the lower end  13 a closed and it is provided, near said end, with a radial hole  17 . The air duct  15 , having a diameter smaller than one of the steam duct, has the end portion  19  tapered and it ends with an axial opening  21 , placed in front of said radial hole  17  of said steam duct  13 .  
         [0027]     A temperature electronic sensor  23 , fit for measuring the temperature of the liquid to be heated, is further fastened to one of said ducts  13 ,  15 . Said sensor  23  is electronically connected to an electronic control unit through a couple of conductors passing inside a protective sheath  25 .  
         [0028]     In  FIG. 2   a  a first embodiment of the hydraulic circuit of the device according to the invention is shown.  
         [0029]     The air duct  15  is provided with a first three-way electrovalve  16 , whose remaining two ways are connected one to the outside environment through a suction pipe  33  that has the end  35  open and the other to a second three-way electrovalve  14  through an intermediate pipe  31 .  
         [0030]     The remaining two ways of said second electrovalve  14  are in their turn connected one to said steam duct  13  and the other to a steam source  27  through a dispensing pipe  29 .  
         [0031]     In such way, according to the opening or closing condition of said electrovalves  14 ,  16  one and/or the other of said ducts  13 ,  15  can be put in communication with said steam source  27  or with the outside environment.  
         [0032]     In particular, thanks to the intermediate pipe  31  that connects the two electrovalves  14 ,  16 , it is possible to introduce steam into the liquid to be heated through both said ducts  13 ,  15 , or, alternatively, to simultaneously introduce into said liquid steam through duct  13  and air through duct  15 .  
         [0033]     Advantageously, thanks to the above-mentioned expedient it is possible to obtain drinks that require different preparation modes.  
         [0034]     For instance, in case said second electrovalve  14  is positioned so to put in communication the steam dispensing pipe  29  both with the intermediate pipe  31  and with the steam duct  13  and said first electrovalve  16  is positioned so to put in communication the intermediate pipe  31  with the air duct  15  and to close said suction pipe  33 , the steam generated from said steam source  27  will reach both the ducts  13 ,  15  and the liquid will be heated, substantially without froth formation.  
         [0035]     In case, on the contrary, said first electrovalve  16  is positioned so to close the intermediate pipe  31  and to put in communication the suction pipe  33  with the air duct  15 , the steam generated from said steam source  27  will only reach the steam duct  13 , while the air duct  15  will be reached by the air sucked from the outside environment and it will be therefore obtained the froth formation during the liquid heating.  
         [0036]     It is evident that, with the device according to the invention, it is possible to set numerous operating cycles based on the sequence of a plurality of steps, each characterised by a set duration and by a different condition of opening/closing of said electrovalves  14 ,  16 , correspondingly obtaining numerous preparation modes of different drinks.  
         [0037]     It is to be noted that, in a preferred embodiment, said steam source  27  consists of a steam jet of an espresso coffee machine for bar and, to this purpose, said pipe  29  can be equipped with means to be tight fastened to said steam jet.  
         [0038]     Alternatively, the device according to the invention can be provided with an autonomous steam generator and it can therefore be used independently from other apparatuses for bar.  
         [0039]     With reference to  FIG. 2   b  a second embodiment of the device according to the invention is shown. In said second embodiment the first three-way electrovalve  16 , instead of being connected through the intermediate pipe  31  to the second three-way electrovalve  14 , is directly connected through a pipe  37  to the pipe  29  carrying steam from the source  27  to the second electrovalve  14  (alternatively, pipe  37  could be connected to duct  13  immediately downstream the second electrovalve  14  as shown in  FIG. 2   b  with the dotted line). In such way, the second three-way electrovalve  14  can be advantageously equipped with a pipe  39  open to the outside at  43  in order to allow the downwards easy flow by gravity of the liquid in case present in the duct  13  that, otherwise, should tend to clog, when said second valve  14  is positioned so to allow the passage from pipe  41  to duct  13 .  
         [0040]     It is to be noted that in the shown examples two three-way electrovalves have been employed for reasons of simplicity and economy, but it will be also possible to provide arrangements that employ a combination of other kinds of electrovalves and connections.  
         [0041]      FIG. 3  is a block diagram that illustrates in a simplified way the electronic control unit  51  of the device according to the invention.  
         [0042]     Said control unit  51  comprises a selector  53  onto which the user can select the kind of wanted drink. The selection carried out onto the selector  53  controls a microprocessor  55 , provided with a storage  57 , within which the data relevant to the operating cycle corresponding to each possible user&#39;s selection are stored.  
         [0043]     On the basis of the instructions stored inside the storage  57  said microprocessor  55  performs a cycle based on a sequence of opening and closing steps of each electrovalve  14 ,  16 .  
         [0044]     Said microprocessor  55  is further connected to the temperature sensor  23 , if this is present. On the basis of the temperature-indicative signal sent by said sensor  23 , the microprocessor  55  can modify the duration of the different steps of the opening and closing cycle of the electrovalves stored inside the storage  57  in order to obtain a drink with the optimum temperature and froth amount.  
         [0045]     As an example, in  FIG. 4  is reproduced a graph that illustrates the operating cycle of the device according to the invention in case of preparing a cappuccino.  
         [0046]     In said graph, on the axis of abscissae the time for preparing the drink is quoted and on the axis of ordinates the milk temperature is quoted.  
         [0047]     During a first step  1 , shown with a dotted line in the graph, said first electrovalve  16  and said second electrovalve  14  are maintained in such a position to simultaneously send steam to both the ducts  13  and  15  and to prevent air entering through the suction pipe  35 .  
         [0048]     When milk reaches a preset temperature T 1 , for instance about 35° C. (or after a fixed time when the temperature control is not present), in a second step  11 , shown with a continuous line in the graph, the first electrovalve  16  is positioned so to allow the air entering through the duct  15  and to prevent steam passing from the intermediate pipe  31 .  
         [0049]     Said first electrovalve is maintained open up to a preset temperature T 2  (or for a fixed time when the temperature control is not present), for instance of 5° C. under the final wanted temperature T 3  (in the example 65° C.).  
         [0050]     Once reached said temperature T 2 , in a third step III, shown with a dot-point line in the graph, said first electrovalve  16  is again positioned so to allow the steam entering also through duct  15  and to prevent air suction through the suction pipe  35 .  
         [0051]     This arrangement is maintained until the preset temperature T 3  is reached, having reached which the second valve  14  is closed so to prevent steam introduction into both the ducts and to allow the removal of the drink.  
         [0052]     Though in the preferred embodiment the ducts of the device according to the invention are directly connected to the steam jet of a professional espresso coffee machine, by following the teachings of WO 01/97668 it will be possible to provide a device comprising a container for the liquid to be heated, wherein said ducts are fastened to said container.