DESCRIPTION

The present invention regards a unit for dispensing hot beverages, particularly but not exclusively for dispensing espresso coffee.

As known, there are various types of coffee machines available in the market. In particular, among the main professional coffee machines there are the following systems for dispensing the water, required for brewing espresso coffee, i.e.:

1 ) the thermosyphon circulation system;

2) the system regarding the saturated brew groups technology.

In the first of the two systems mentioned above, the dispensing water is heated and kept in circulation both due to the transfer of heat, which occurs through heat exchangers arranged in the service boiler and the water pressure of the water supply system. This circulation effect maintains the system's temperature required for dispensing espresso coffee.

On the one hand, whereas such thermosyphon circulation system enables using water from the water supply system for dispensing espresso coffee as well as for continuously dispensing coffee at a constant pressure of 9 bars, on the other hand it reveals the following drawbacks:

- interdependence between the service boiler dispensing circuits;

- difficulty to control the coffee beverage dispensing temperature;

- considerable energy consumption.

From now henceforth, the expression "dispensing water" shall be used to indicate the water that is dispensed by the coffee machine and that is dispensed into a coffee cup after being suitably mixed with the coffee powder contained in the filter holder.

The second system provides for the presence of two boilers: one for dispensing the coffee beverage and the other for the service boiler.

Such system provides for that the water for dispensing the coffee beverage be heated and directly drawn by a saturated brew boiler directly connected to the coffee dispensing unit, instead of from the water supply system. The espresso coffee dispensing unit is maintained at the required temperature by the transfer of heat that occurs between the boiler and the dispensing unit. From now henceforth, the expression "dispensing unit" will be used to indicate an assembly of components comprising a boiler provided with heating elements and a filter holder unit containing the coffee powder, through which there is dispensed a given amount of coffee beverage enough to fill a cup. Whereas such second dispensing system on the one hand enables fairly precisely controlling the coffee beverage dispensing temperature and ensures that the water dispensing temperature no longer depends on the boiler pressure, on the other hand it reveals the drawback of using impure water (stagnant) for dispensing the coffee. Actually, in this case the dispensing water is not directly drawn from the water supply system but from a saturated brew boiler.

The saturated brew groups technology then developed from a dual boiler system to a multiboiler system in which there is a boiler for each dispensing unit and a boiler for the service boiler.

Whereas the multiboiler system on the one hand enables good control of the temperature of the dispensing water (and thus the coffee) for each dispensing unit, on the other hand it reveals the following drawbacks:

- interdependence of the coffee beverage water dispensing circuit with respect to the service boiler water circuit; in this case, the thermal stability of the system is bound to the operation of the service boiler;

- lack of actual reduction of energy consumption, due to the fact that the overall efficiency of the system requires the operation of both the coffee beverage water dispensing circuit and the boiler water circuit.

Patent document DE 20 201 1 050945 U1 illustrates a unit for dispensing hot beverages, particularly for espresso coffee, comprising:

- a main body with at least one filter holder unit;

- a boiler connected to the main body;

- a first circuit, inside the boiler, for heating the water present therein;

- a second circuit, independent from the first circuit, for conveying the dispensing water towards the filter holder unit.

Patent document US 1 631 753 A illustrates an electrical water heater, comprising a plurality of ducts spiral-wound and coaxial with respect to each other.

The aim of the present invention is to overcome the aforementioned drawbacks. In particular, an object of the present invention is to provide a hot beverage dispensing unit having a system for a more accurate control of the water temperature during dispensing and that enables a more constant water dispensing temperature with respect to systems of the known type.

A further object of the present invention is to provide a unit for dispensing hot beverages, particularly espresso coffee, capable of reducing the times required to reduce the dispensing temperature during the time that elapses between the just terminated dispensing of a cup of coffee and the immediately subsequent dispensing.

The aforementioned objects are attained by the present invention regarding a dispensing unit whose main characteristics are outlined by claim one.

The aforementioned objects are also attained by an espresso coffee machine whose main characteristics are outlined by claim twelve.

Further detailed characteristics of the invention are outlined in the dependent claims.

Advantageously, the dispensing unit according to the invention does not provide for any direct contact between the dispensing water and the heating elements of the service boiler.

Still advantageously, the dispensing unit according to the invention provides for the instantaneous heating of the amount of dispensing water required to obtain the espresso coffee beverage conferring greater consistency to the coffee dispensed into a cup.

Still advantageously, the dispensing unit according to the invention provides for a water dispensing circuit in which there is no direct contact between the dispensing circuit and the thermosyphon circuit, i.e. they are entirely independent with respect to each other. Thus, the dispensing water has no direct contact with the heating element (resistor) belonging to the thermosyphon circuit.

Still advantageously, the coffee machine according to the invention provides for a water dispensing circuit that can be entirely made using material suitable for handling food products.

The aforementioned objects and advantages shall be more apparent from the description of a preferred embodiment of the invention, outlined hereinafter by way of non-limiting example, with reference to the attached drawings, wherein: - fig. 1 represents a plan view of the dispensing unit according to the invention;

- fig. 2 represents a sectional view of fig. 1 along line A-A;

- fig. 3 represents a further sectional view of fig. 1 along line E-E;

- fig. 4 represents a further sectional view of fig. 1 along line C-C;

- fig. 5 represents a further sectional view of fig. 1 along line D-D;

- fig. 6 represents a further sectional view of fig. 1 along line B-B;

- fig. 7 represents a further sectional view of fig. 1 along line F-F;

- figs. 8 and 9 respectively represent the axonometric view and the sectional view of a detail of a cartridge visible in fig. 2;

- fig. 10 represents an enlarged view of the detail of fig. 2 indicated with K;

- figs. 1 1 and 12 respectively represent two sectional views of an insert for adjusting the air/water mixture shown in two different operating configurations, which is inserted into area K of fig. 2;

- fig. 13 represents an axonometric view showing - in detail - the connection of the channels for the flow of the dispensing water visible separately in figs. 2, 4, 7 and 10.

With reference to figs. 1 and 2, there is observed a dispensing unit, generally indicated with 1 , comprising a main body 2 provided with a coffee filter holder unit 3 removably constrained to the main body 2.

With reference to fig. 2, it is observed that the dispensing unit 1 comprises a boiler 4 mechanically connected to the main body 2 and provided with one or more heating elements 5 constrained to the bottom 6 thereof and suitable to heat the water contained therein.

In particular, in the present embodiment, the water X contained in the boiler 4 is heated by a resistor 5 and it constitutes the water of the boiler of the thermosyphon circulation circuit.

Once heated, the water X is conveyed upwards up to reaching a first thermosyphon duct 7, visible in figs. 3 and 5, which conveys the thermosyphon circulation water X towards the filter holder unit 3, and in particular towards the area of the coffee filter.

Following a path 70 of the annular type, as observable in fig. 3, the water then returns with a temperature lower than the heating one along a second thermosyphon duct 8, visible in figs. 3 and 6, until it flows into the boiler 4 again.

Basically, there is a first circuit of the self-supporting thermosyphon type in which there occurs a convective circulation of the water X due to the sole difference of density between water volumes at different temperatures.

With particular reference to figs. 4 and 7, there is also identified a second circuit for dispensing water Y into the cup of coffee, which directly draws water Y coming from the water supply system at about 15-20°C through a first inlet duct 9 and conveys it towards the filter holder unit 3 through a second outlet duct 15 and a solenoid valve 23. The operation of such second dispensing circuit will be explained further in detail hereinafter.

According to the present invention and with reference to figs. 2, 4, 5, 6 and 7, the dispensing unit 1 comprises a cartridge 10 submerged in the water X contained in the boiler 4 and belonging to the second circuit for dispensing water Y.

As observable in fig. 7, the cartridge 10 is connected:

- to the first inlet duct 9 which conveys the water Y from the water supply system;

- to the second duct 15 for the outflow of water Y.

The cartridge 10, visible with greater detail in figs. 8 and 9, is constituted by a first component 11a, which is preferably made of a copper alloy compatible with the food production industry, and a second tubular component 11 b preferably made of stainless steel.

Such first component 11a is preferably obtained using the CNC technology and on the outer section thereof there is obtained a helical channel 12.

Still with reference to fig. 8, the helical channel 12 is a double-helix channel in which the helices 121 and 122 extend parallel to each other.

On the upper surface 13 of the cartridge 10 there are obtained two mutually spaced holes in which there are identified:

- an inlet hole 14a connected to the helix 121 ;

- an outlet hole 14b connected to the helix 122.

Such holes 14a, 14b respectively constitute the beginning and the end of the double-helix channel 12 and they are obtained in a manner such that the channel 12 begins and ends on the same side as the cartridge 10.

Advantageously, in the double-helix channel 12 the fluid, water in this case, that traverses the helix 121 flows against the current with respect to the fluid that traverses the other helix 122.

Still advantageously, such helical path of the fluid obtains a heat exchange which occurs against current and it is thus more efficient than a heat exchange that occurs with the fluid that flows according to a single flow direction. Thus, the temperature of the water Y is raised to the temperature selected as a function of the coffee blend to be transformed.

Advantageously, the aforementioned second tubular component 11 b is sealingly splined on the first component 11a and serves as a jacket for the cartridge 10 so as to define, coupled with the first element 11a, the aforementioned helical channel 12 (which is an airtight sealed channel).

With reference to fig. 9 it is observed that, while the element 11a made of copper alloy is an optimal heat conductor (and thus transfers heat from the delivery water X of the thermosyphon circuit to the water Y of the dispensing circuit), the element 11 b, being made of stainless steel, is a material with low heat conductivity and thus serves as an insulator.

Advantageously, the fact that the element 11 b is an airtight insulator enables insulating the first thermosyphon circuit of the dispensing unit 1 against the second circuit for dispensing water Y, which also includes the cartridge 10.

Still advantageously, the combination of the aforementioned two materials, i.e. copper as the inner component of the cartridge 10 and the stainless steel as the outer component thereof, generates a temperature differential which maintains the temperature of the first thermosyphon circuit constant.

With reference to fig. 2, over the electrical resistor 5 there was positioned a first insert 40 provided with a calibrated hole 41.

Advantageously, such calibrated hole 41 , also directly obtainable in the cartridge 10, constitutes a constriction and thus an obstacle to the outflow of water X heating the thermosyphon circuit, so as to increase the pressure thereof and create a turbulent flow of water X.

The pressure differential generated by the calibrated hole 41 , still advantageously, triggers the circulation of water in the thermosyphon circuit, visible in fig. 3, and enables maintaining the thermosyphon circuit water at the required temperature.

The cartridge 10, besides the aforementioned first duct 9 for the inflow of the dispensing water Y, is provided with a second duct 15 for the outflow of the dispensing water towards the solenoid valve 23 (see fig. 13).

The dispensing water flowing out from the second duct 15 is conveyed towards the solenoid valve 23 through a third supply duct 25, visible in figs. 4 and 13. The operation of the second dispensing circuit will be illustrated further in detail hereinafter.

To the dispensing unit 1 there is also associated an outer pump (not visible in the figure), of the per se known type, which serves to maintain the water Y pumped in the dispensing circuit at a pressure value comprised between 9 and 15 bars.

As concerns the filter holder unit 3, as observable in fig. 2, it comprises a diffuser 30, placed in communication with the third supply duct 16, and an underlying filter holder container 31 , suitable to be filled with the desired coffee powder blend.

Underlying the filter holder 31 there is present an element 32 for supporting the filter holder container 31 itself, to which there is laterally connected a gripping element 33 to be grasped by the user.

After mixing with the water Y of the dispensing circuit, the coffee beverage flows out through an outlet 34.

Still with reference to fig. 2, the dispensing unit 1 is insulated, at the upper part, with respect to the external environment by means of a cover 21 that is internally provided with a plurality of air interspaces 22 suitably spaced from each other.

Advantageously, such air interspaces 22 insulate the upper surfaces of the filter holder unit 3 from the external environment and thus enable considerable energy saving in terms of lesser amount of kW absorbed by the dispensing unit 1.

With reference to fig. 10, in communication with the second outlet duct 15 of the dispensing circuit there is present a pre-infusion chamber 50.

According to a preferred embodiment, the pre-infusion chamber 50, in combination with a second insert 51 contained therein, has the function of improving the mixing of water and air during the dispensing of the coffee beverage, thus generating foam.

Preferably but not necessarily, the second insert 51 , illustrated in figs. 1 1 and 12, is housed in the pre-infusion chamber 50, at the area K shown in fig. 2. The insert 51 is threaded and the thread thereof can be conjugated with that of a partly threaded seat 52, obtained in the main body 2 of the dispensing unit 1. Thus, the second insert 51 can be inserted by screwing in the aforementioned seat 52. As observable in figs. 1 1 and 12, the second insert 51 is in communication with the outlet of the third supply duct 16 of the dispensing circuit through a first channel 53 which extends inside the insert 51. However, according to a variant embodiment not represented in the figures, the second insert 51 may be positioned differently.

At the upper end of the first channel 53 there are two holes, respectively 54a and 54b, spaced from each other.

Still with reference to figs. 1 1 and 12, the insert 51 is sealingly inserted into the seat 52 by means of an O-ring 55 and it can be manually screwed/unscrewed in such seat 52 by the user.

The presence of the insert 51 advantageously enables the user to regulate the amount of foam present in the dispensed coffee, as explained further in detail hereinafter.

Operatively and with reference to all the figures, the dispensing unit 1 operates as follows.

In order to maintain the filter holder unit 3 at the required temperature, the boiler 4 is already provided filled with the fluid X.

The water/fluid X of the thermosyphon circuit is then heated by the resistor 5 and, by heating, it rises by convection through the calibrated hole 41 until it enters into the first thermosyphon duct 7 (see fig. 5) along the annular thermosyphon circuit 70.

In the annular circuit 70 the water X returns colder through the second thermosyphon duct 8 (see fig. 6) before returning to the boiler 4 and being heated again by means of the resistor 5.

As regards the operation of the cartridge 10 submerged in the boiler 4, the water Y of the dispensing circuit is drawn from the water supply system and it is conveyed towards the cartridge 10 through the inlet duct 9 (see fig. 7). As observable in fig. 7, the first inlet duct 9 has a first substantially vertical portion 9a and a second portion 9b substantially orthogonal to the first portion 9a.

Advantageously, such configuration enables the water Y, which flows into the first inlet duct 9 of the dispensing circuit, to change the flow thereof from laminar to turbulent at the elbow portion 90 of the first inlet duct 9.

Thus, the water that passes through the helical channel 12 of the cartridge 10, having taken a turbulent flow, considerably increases the heat exchange surface of the water Y and this enables the temperature increase of the dispensing water Y.

The dispensing water Y thus heated flows out from the second duct 15 of the dispensing circuit and reacquires a substantially laminar flow at the elbow portion 150 of the second outlet duct 15 of the dispensing circuit.

As observable still in fig. 7, the second outlet duct 15 has a configuration similar to that of the first inlet duct 9, and thus it has a first substantially vertical portion 15a and a second portion 9b substantially orthogonal to the first portion 9a.

After flowing out from the second duct 15, the heated water Y is conveyed to the solenoid valve 23 which, once activated, enables the water Y coming from the water supply system and heated in the cartridge 10 to flow towards the duct 16 and thus towards the filter holder unit 3 to be mixed with the coffee and be dispensed into a cup (not visible in the figures).

Should the second insert 51 be present in the pre-infusion chamber 50, when the filter holder unit 3 is decoupled, the air which is conveyed through a second channel 56 towards the seat 52 of the insert 51 flows in from the external environment.

In the meanwhile, the dispensing water flowing out from the duct 24 flows into the first channel 53 inside the insert 51 and it flows out from the two holes 54a and 54b, mixing with the external air flowing into the second channel 56.

When the insert 51 is completely screwed into the seat 52 (see fig. 12), the air chamber 57 that is created in the seat 52 reaches the minimum volume thereof and thus there is a minimum air volume which leads to an equally minimum creation of foam in the coffee cup.

Vice versa, as observable in fig. 1 1 , when the user unscrews the insert 51 from the seat 52 thereof, the air chamber 57 expands reaching the maximum volume thereof. In this case, the amount of air is maximum and thus there will be an amount of maximum foam in the coffee cup.

Thus, this air/water mixing system advantageously enables regulating the amount of foam provided to the coffee dispensed in the cup.

In the light of the above it is observable that the dispensing unit and the coffee machine according to the invention attain the pre-set objects.

In particular, the object of obtaining a constant regulation system of the dispensing temperature due to an optimised heat insulation system with a dispensing temperature error that revealed to be equivalent to ±0.5°C is attained. This result is attained with a drastically reduced power for each dispensing unit; thus, this enables considerable energy saving with respect to coffee machines of the known type.

In addition, the object of overcoming the problem related to the heat inertial of the dispensing unit according to the invention is attained in that now the inflowing water, coming from the water supply system at 15-20°C, is brought to the desired temperature (about 90°C) directly towards the dispensing circuit to dispense coffee into a cup without having to be previously mixed neither with the water of the thermosyphon circuit nor with that of the service boiler. This implies that the dispensing unit according to the invention can dispense coffee into a cup within a shorter period of time than that required with the current systems.

Advantageously, in the dispensing unit according to the invention there is no direct contact between the dispensing water and the heating element of the boiler of the thermosyphon circuit.

Still advantageously, the low operating pressure of the thermosyphon circuit of the dispensing unit according to the invention enables using boilers made of polymeric material supplied with distilled water or other fluids, so as to eliminate the deposit of scale on the heating element.

Still advantageously, the helical channel of the aforementioned cartridge can be dimensioned in a manner such to contain the precise amount of water required to dispense the required espresso coffee.

Still advantageously, the coffee machine according to the invention is provided with one or more dispensing units all independent from each other and all being independent from the thermosyphon circuit of the boiler, this avoiding the need to pre-mix the water coming from the water supply system with the water of the thermosyphon circuit.

Furthermore, the independence of the thermosyphon circuit from the water supply system pressure makes the circulation speed of the thermosyphon circuit water constant, thus obtaining a more homogeneous heating of the dispensing unit in all steps thereof.

Lastly, besides maintaining the dispensing temperature of the coffee beverage over time during the dispensing subsequent to the first one, the dispensing unit according to the invention also enables maintaining the organoleptic properties of the coffee beverage present in the cup unaltered over time.