WO2022107008A1

WO2022107008A1 - Household machine for preparing hot beverages by infusion

Info

Publication number: WO2022107008A1
Application number: PCT/IB2021/060641
Authority: WO
Inventors: Tommaso BECCUTI
Original assignee: Additive Appliances S.R.L.
Priority date: 2020-11-18
Filing date: 2021-11-17
Publication date: 2022-05-27
Also published as: WO2022107008A9; IT202000027648A1

Abstract

A household machine or appliance for preparing hot beverages by infusion or percolation is disclosed, comprising a body which includes a boiler reservoir, at least one infusion tank and at least one dispensing duct for the beverage, wherein the infusion tank communicates with the boiler reservoir through at least one transport duct which comprises a cooling portion for the infusion liquid integrally formed in at least one wall of the machine body or in a supporting structure of the machine, or that constitutes at least part of a wall of the machine body or of a supporting structure of the machine, which wall or supporting structure is in a heat exchange relationship with the external environment, pressure release valve means being arranged along the transport duct, upstream of the cooling portion for the infusion liquid.

Description

Household machine for preparing hot beverages by infusion

The present invention generally relates to household machines for preparing hot beverages by infusion, such as coffee machines or stove-top coffee makers having the characteristics recalled in the preamble of claim 1.

Coffee and its preparation, in particular the preparation of the so-called Italian espresso, have been the subject of numerous and in-depth scientific studies due to the beverage’s growing popularity worldwide. Today, it is widely documented that the optimal extraction of espresso coffee is the result of various chemical-physical factors. Among those factors, the pressure and temperature of the infusion liquid (water), which must be 9 ± 2 bar and 90 ± 5 ⁰ C respectively, are of primary importance.

Since their invention, at the dawn of the twentieth century, the machines able to obtain these performances were expensive and large, remaining the prerogative of professionals, bars and coffee shops. Regardless of their well-known process’ limitations, the traditional percolation systems -which we define here as thermomechanical- have provided an acceptable alternative for home consumers, as in the case of the famous and internationally recognized pressurized moka pot, invented by Alfonso Bialetti in 1933.

The development of electronics has radically changed that scenario. Introduced in the second half of the last century, electronic household machines for preparing hot beverages have spread rapidly over the last few decades -also thanks to the advancement of technology, which has gradually made them more efficient and cheaper.

The improvement in performance, particularly of the dispensed infusion’s quality, is a direct consequence of the optimization of the extraction process; that optimization belongs to the integration of electronic components which accurately control the quantity, pressure and temperature of water. Furthermore, most of the electronic coffee machines today on the market give the possibility to prepare beverages from coffee capsules or pods having the characteristic of containing pre-measured quantities of ground coffee -thus significantly simplifying the beverage’s preparation procedure. Recently, however, concerns on the environmental impact of the so-called "portioned" consumption (i.e. based on single doses enclosed in capsules, pods or sachets), together with some technical limitations of the machines, are favouring a repositioning of consumers. To date, around 40 billion coffee capsules are produced worldwide each year, and only a fraction of them are compostable. Furthermore, on top of their not-negligible environmental cost, capsules also have the characteristic of being way more expensive than traditional ground coffee -on average, by a factor of more than four.

Additionally, from a purely technical angle, current household machines for preparing hot beverages, both electronic and thermo-mechanical (or thermoelectric yet non-electronic), have the following limitations.

The overall size of electronic machines is greater than traditional infusion systems’s size (e.g. such as the moka pot). Particularly, the electronic components aimed at pressurizing and controlling the water’s temperature -more generally of the infusion liquid- and their central control system, increased the finished product’s overall volume. That causes a problem of space occupation, particularly where it is limited, and a more general problem related to the device’s portability. Furthermore, the impact of these additional components is also tangible from a cost perspective, both on direct and assembly costs.

In addition, the vibration pump that pressurizes the infusion liquid -though economical and effective- creates strong vibrations that stress the body of the machine, resulting in a particularly noisy extraction process. Although tolerated, this characteristic is generally perceived as penalizing, particularly during some of the beverage key consumption moments.

Thermomechanical machines as well as non-electronic thermoelectric machines (by nonelectronic thermoelectric machines we mean alternative versions of thermomechanical machines in which the infusion liquid’s heating takes place through an electric source, by Joule effect or by induction, and not by absorbing thermal energy from a stove-top or developing thermal energy by induction from a stove-top), traditional percolation systems, since they do not use the vibration pump are more compact and noiseless than electronic machines. However, the lack of control-electronics requires a compromise on the extraction process, both in terms of maximum pressure reached (generally too low) and control of the temperature (generally too high). For instance, in the traditional stove-top moka, as documented by Navarini et Al. In "Experimental investigation of steam pressure coffee extraction in a stove-top coffee maker" [Elsevier, Applied Thermal Engineering 29 (2009)] the pressure reaches about 2 bar and causes an excessive increase in the water’s boiling temperature, therefore in the percolation temperature, which exceeds 120 ⁰ C at the end of the process; that causes the extraction of unwanted aromatic substances, which are organoleptically perceived as “bitter” and “burnt” tastes, lowering the infusion’s quality.

As a further consequence, traditional thermo-mechanical machines (e.g. moka pot) do not produce the typical foam layer that characterizes espresso coffee -and that many coffee consumers appreciate. The foam’s formation process is complex and depends on several factors, some downstream of the extraction process (for example, roasting, storage, grinding, and the coffee variety itself), others related to the infusion process: it is known that the foam is generated during the percolation of the heated infusion liquid through the coffee tank only above certain pressure values. A traditional machine such as the moka pot cannot deliver the pressurization of 9 bar required for the preparation of an espresso coffee; if the pressure was significantly increased, for example through the use of a valve, the consequent increase in the water’s boiling temperature would not allow an extraction within optimal average values.

Already in 1935, CH 177917 A proposed an additional tank adapted to cool down the heated and pressurized infusion liquid; that solution, however, on top of using an additional component, required using cold water to reach the desired temperature. A similar solution was also disclosed by FR 2186209 Al and FR 2347014, once again using a coolant liquid placed inside an additional component.

WO 94/07400 Al has adapted a spiral cooling system, external to the machine, to a traditional percolating system. Like in the previously cited cases, however, the proposed solution does not allow high efficiency heat exchange, and the temperature drop is insufficient to operate the system at high pressure. In addition, the spiral cooling system is an additional component that increases the footprint of the machine.

In recent years, heat exchangers have been used in multifunction machines, capable of delivering both hot and cold beverages. For example, in WO 2012/036635 Al and in CN 104586257 A the cooling system -or heat exchanger- is added to traditional components (pump, temperature sensor, controller, etc.) and provides a system for cooling the beverage after percolation.

US 2,550,902 describes infusion liquid’s rising channels inside the machine’s handle; their scope is to channel the infusion liquid upward, therefore the handle is suitably coated with insulating material -so as to avoid heat dispersion and consequent burns to the person serving the beverage.

In EP 0162305 an infusion liquid’s rising duct allows the temperature of the infusion liquid to be controlled, albeit limiting heat dissipation to a few degrees centigrade and consequently not providing any valve for further pressurization of the infusion liquid.

WO 2019/232109 Al proposes a device for infusing and dispensing coffee comprising a multi-chamber brewing unit mechanically coupled to a boiler reservoir and a collecting reservoir. The heated brewing liquid is directed into a pressurization chamber and then to an upper preparation chamber, which contains a perforated basket adapted to receive a predetermined quantity of coffee, and the heated and pressurized brewing liquid mixes with the coffee to create the beverage, which is then directed -under pressure- through a filter (aimed at retaining coffee powders) before reaching the final collecting reservoir -where it is supplied at a given dispensing temperature and pressure. In order to reduce the brewing liquid’s temperature and achieve higher pressure, the document suggests mixing a quantity of cold water in the pressurization chamber.

The present invention aims to provide a satisfactory solution to the problems described above, both of electronic machines and of thermoelectric and thermomechanical ones, avoiding the drawbacks of the known art. In particular, the invention aims to ensure accurate control of the water’s (or infusion liquid) temperature and pressure (and their thermodynamic balance) in a household machine or appliance for preparing hot beverages by infusion or percolation, even at high temperature and pressure values, without using a pressurization pump (e.g., vibration pump) and auxiliary temperature control components.

According to the present invention, this aim is achieved thanks to a household machine or appliance for preparing hot beverages by infusion or percolation having the characteristics referred to in claim 1.

Particular embodiments form the subject of the dependent claims, whose content is to be considered as an integral part of the present description.

To summarize, the present invention proposes a household machine or appliance (these terms will be used interchangeably in the rest of the description) for the preparation of hot beverages by infusion or percolation equipped with a temperature control system, specifically an infusion liquid’s cooling system, implemented by means of a heat exchanger, or a heatsink circuit, with complex geometry, which is integrally embedded in the machine's structure, or constitutes itself said structure or a part thereof.

Recent studies and publications have shown how the use of 3D printing, or additive manufacturing, allows the manufacturing of heat exchangers with complex geometries, that have superior thermo-mechanical characteristics. In particular, in "Engineering Calculations for complex geometric domains" (MATEC Web Conference 157, 02009, published in 2018) it is demonstrated how geometric structures obtained from implicit functions, for example the so-called Triply Periodic Minimal Surface (TPMS), like gyroid structures, offer high performance in terms of dissipative capacity per unit-volume. Given their complexity, actually, many of these structures can only be manufactured through additive manufacturing technologies. The present invention, taking advantage of 3D printing and of its ability to create complex geometries, leverages a cooling system for the infusion liquid which includes a high efficiency heat exchanger, or heatsink, shaped according to a triply periodic minimal surface, that is embedded in, i.e. made in a single piece with, the machine’s structure and therefore conformal thereto . Such a heat exchanger with complex geometry is adapted to intercept the heated infusion liquid on its way toward the infusion tank, causing a controlled cooling before it reaches said tank. The high heat dissipation caused by the heat exchanger’s duct with complex geometry guarantees a substantial drop in the infusion liquid’s temperature, allowing for a high pressure extraction even when the pressurization takes place thermomechanically -without an aid from an electronic control- as in the previously defined traditional percolation systems. In fact, it is known how the boiling point of water increases as pressure increases. For instance, a pressure of 9 bar corresponds to a water boiling temperature of about 175 ⁰ C, a value almost doubling the optimal infusion temperature of 90 ⁰ C ± 5 ⁰ C.

Conveniently, the heat exchanger duct with complex geometry, optimized and integrally embedded in the machine’s structure guarantees enough total dissipative capacity to reduce the infusion liquid’s temperature consistently with the values indicated above.

Advantageously, pressure and temperature’s control can thus be obtained by thermomechanical action without needing an electric vibration pump and possible auxiliary electronic temperature control circuits which are bulky, expensive and noisy.

As anticipated, the (high efficiency) heat exchanger duct with complex geometry is advantageously integrally embedded in the machine’s structure by leveraging 3D printing or additive manufacturing technologies both directly, i.e. through the direct production of the product or component, and indirectly, i.e. through the production of tooling for “conventional” manufacturing processes such as injection molding or casting. Specifically, said heat exchanger can be easily embedded in a wall of the machine’s body which is in a heat exchange relationship with the external environment or, similarly, in a supporting structure of the machine in a heat exchange relationship with the external environment, and therefore adapted to be "conformal" with the geometries of the machine itself, as well as functionally optimized (thus, maximizing the total dissipative capacity per unit volume) thanks to the complexity of the geometries that can be created.

Even more advantageously, the heat exchanger duct manufactured in this way does not occupy additional spaces of the machine.

A further advantage is obtained by manufacturing the wall of the machine body or the supporting structure of the machine in a heat exchange relationship with the external environment, with a minimum periodic triple surface open to the external environment, thus expanding its dissipative surface.

In conclusion, the solution of the invention allows, on the one hand, the manufacturing of a household electronic machine for producing hot beverages that does not require auxiliary pressurization and temperature control devices (thus being more compact and noiseless) though delivering the same performance. On the other hand, it allows the manufacturing of a thermomechanical (or thermoelectric, but not electronic) machine that is able to accurately control the water's (or infusion liquid) temperature and pressure even at high pressure and temperature values, such as those necessary for the preparation of an espresso coffee.

Further characteristics and advantages of the invention will be set out in more detail in the following detailed description of its embodiments, here provided as a non-limiting example with reference to the attached drawings, in which:

Figure 1 is a schematic representation of a household machine or appliance for preparing hot beverages by infusion or percolation, according to the invention;

Figures 2a-2c are respectively lateral elevation, perspective and frontal elevation views of a first embodiment of a machine or appliance according to the invention; figure 3 is a perspective view of a variant of the embodiment of figures 2a-2c;

Figures 4a and 4b are lateral elevation and perspective views, respectively, of a second embodiment of a machine or appliance according to the invention;

Figures 5a and 5b are lateral elevation and perspective views, respectively, of a boiler reservoir of the machine or appliance of the embodiment of the invention depicted in Figures 4a and 4b; Figures 6a-6c are respectively side elevation, perspective and top views of an infusion tank of the machine or appliance of the embodiment of the invention depicted in Figures 4a and 4b;

Figures 7a-7c are side elevation, perspective and top views, respectively, of a collecting reservoir of the machine or appliance of the embodiment of the invention depicted in Figures 4a and 4b; and

Figure 8 is a block diagram of a method for manufacturing a machine or appliance according to the invention.

In the figures, identical or functionally equivalent elements or components are indicated with the same references.

Figure 1 schematically shows a household machine or appliance for preparing hot beverages by infusion or percolation according to the invention.

The machine, as a whole, is indicated with 10. It includes a boiler reservoir 12 which has at least one chamber 12a adapted to contain an infusion liquid to be heated, at least one infusion tank 14 adapted to receive a predetermined quantity of powder substance, and at least one duct 16 to dispense the beverage obtained from the infusion of said powder substance, adapted to pour the beverage into a collecting receptacle or reservoir 18, which can be external or integrated with the machine.

The reference numeral 20 indicates in the figure a heat source external or integrated with the machine, with which the boiler reservoir 12 is associated to receive heat to be transferred to the chamber 12a containing the infusion liquid to be heated.

The infusion tank 14 communicates on one side with the boiler reservoir through at least one duct 20 aimed at transporting the heated infusion liquid, and on the other side, with the beverage dispensing duct 16 through filtering means 22 adapted to retain the powder of the infused substance once the infusion liquid percolates through it. The duct 20 transporting the heated infusion liquid, comprises a collector portion 20a of the infusion liquid, at least partially immersed in the chamber 12a of the boiler reservoir, and a portion 20b aimed at controlling the infusion liquid’s temperature, more properly to cool it down, which is integrally embedded in a machine’s wall W or in a supporting structure of the machine body which is in a heat exchange relationship with the external environment. “Machine body’s wall” is intended as a supporting structure of the machine or a nonsupporting element that separates a room or space of the machine from the external environment or from another environment of the machine in a heat exchange relationship with the external environment.

The cooling portion 20b has a mass and a surface extension, per unit volume, which sets its heat dissipation capacity. This portion forms a heat exchanger or heatsink duct. The topology of the heat exchanger or heatsink duct is designed in such a way as to provide a heat exchange surface adapted to transfer a predetermined quantity of heat from the infusion liquid, which depends on the expected temperature of the infusion liquid passing through the duct. For instance, the cooling portion 20b is shaped according to gyroscopic geometries such as a triple periodic minimal surface and comprises for example one or more gyroid structures separate from each other, or communicating one with the other, wherein the total heat exchange surface comprises the internal surface of the gyroid lapped by the infusion liquid- and possibly the surface of a gyroid configuration, or in general of a triple periodic minimum geometry, obtained on one face of the wall or of the supporting structure in a heat exchange relationship with the external environment. In a variant embodiment, the cooling portion 20b is a channel, or a non-directional cavity, of any shape. Therefore, the gyroid-shaped representation of Figure 1 is purely indicative and not limiting the invention.

The infusion liquid transport duct 20 also includes a pressure release valve 30, arranged upstream of the cooling portion 20a, adapted to control the pressure of the infusion liquid entering the transport duct from the boiler reservoir. The valve means 30 acts in such a way as to counteract the increasing force exerted by the infusion liquid in the boiler reservoir, as the temperature increases in the heating process, and opening when the pressure increases beyond a predetermined threshold (equivalent to the valve calibration value), allowing the infusion liquid to flow in the transport duct 20a towards the infusion tank. A first embodiment of the machine of the invention is shown by way of example in figures 2a-2c and 3.

Overall, the machine has a cylindrical footprint, and in the exemplary configuration described here the body of the machine includes a casing C which has a semi-cylindrical portion C, and a hemispherical portion C" at the top of it. The boiler reservoir 12, part of the duct 20 for transporting the heated infusion liquid, and the pressure release valve means 30 are mainly housed in the semi-cylindrical portion C, while the infusion tank 14 is mainly housed in the hemispherical portion C", together with the related filtering means 22 and the beverage dispensing duct 16.

The boiler reservoir 12 is preferably equipped with a heating system, for example comprising induction or Joule-effect heating means arranged within the chamber containing the infusion liquid to be heated, or alternatively comprising induction or Joule-effect heating means arranged in a heat exchange relationship with the chamber adapted to contain the infusion liquid to be heated by thermal conduction through the walls of said chamber.

The portion 20b of the transport duct aimed at cooling the infusion liquid is formed integrally in the body of a wall W of the semi-cylindrical portion C 'of said casing.

The body of the machine also includes a supply duct 32 for the infusion liquid from the outside, which is in communication with the boiler reservoir 12 for loading the infusion liquid into the boiler reservoir. The supply duct passes through both the casing portions C and C" and is equipped with a hermetically sealing lid or cap 32a placed on its upper end for loading access purposes. In the lower end portion, instead, the supply duct directly communicates with the boiler reservoir and preferably penetrates it for a minimum portion thereof.

The duct 20 for transporting the heated infusion liquid that emerges from the boiler reservoir 12 has a collecting portion 20a of the infusion liquid which plunges in the chamber 12a of the boiler reservoir for almost all of its length, so that it ends near the bottom of the reservoir, and a rising channeling for the infusion liquid towards the infusion tank, outside of the boiler reservoir, which defines the cooling portion 20b of the infusion liquid.

The boiler reservoir 12 is also preferably equipped with a safety valve (not shown).

The rising channeling for the infusion liquid is coupled to a pressure release valve 30 preventing the infusion liquid from rising until it reaches a predetermined calibration pressure in the boiler reservoir, as a consequence of which the infusion liquid is released into the cooling portion 20b which acts as a heat exchanger, yielding the excess heat. Advantageously, this portion is integrally embedded in the wall’s body W of the semi- cylindrical portion C of said casing facing the outside of the machine or it constitutes said wall, which in the exemplary embodiment shown in the figures faces a semi-cylindrical compartment S complementary to the semi-cylindrical portion C of the casing, aimed at receiving a container to collect the beverage.

The shape and dimensions of the cooling portion 20b acting as a heat exchanger are designed in compliance with the expected temperature of the infusion liquid heated by the boiler reservoir, which depends on the calibration pressure of the pressure release valve 30, and on the desired infusion temperature - typically between 85 ⁰ C and 95 ⁰ C. More generally, they can be configured and manufactured in a personalised way in a production step of the machine according to individual consumers’ preferences, i.e. to the desired thermodynamic balance (temperature, pressure) depending on the quantity of infusion liquid - i.e. on the volume of the chamber of the boiler reservoir - and on the quantity of powder substance - i.e. the volume of the infusion tank - that characterize the machine.

Downstream of the cooling portion 20b, the transport duct comprises a connecting portion 20c suitable for conveying the infusion liquid (thus cooled) to flow dividing means 34 designed to divide the infusion liquid’s flow entering the infusion tank 14.

The filtering means 22 are arranged downstream of the infusion tank and adapted to retain the residues of the powder substance received in the infusion tank, where it undergoes infusion, and the beverage dispensing duct 16 is coupled to them at the outlet thereof. In the embodiment shown in Figures 2a-2c and 3, the beverage dispensing duct 16 is partially housed in the hemispherical portion C " of the casing and has a dispensing nozzle N exposed outside the machine's casing, facing the semi-cylindrical compartment S intended to accommodate a beverage collecting container.

The infusion tank 14 is advantageously accessible through a door opening, equipped with a suitable gasket to ensure hermetic sealing, or other functionally equivalent solution.

Figure 3 shows a variant of the embodiment described, in which the temperature control portion 20b includes a plurality of T-shaped fins designed to further increase the heat exchange surface in contact with the external environment. In a currently preferred embodiment, said geometries aimed at increasing the heat exchange surface have more complex topological characteristics than those exemplary introduced here; for instance, these geometries can be derived from the TPMS (Triply Periodic Minimal Surface) functions already mentioned, and therefore have a gyroscopic conformation (or other TPMS). A protection grid G is conveniently placed in front of the wall W, and is adapted to avoid direct contact of a user with the heat exchange wall.

The procedure for preparing a hot beverage (for example, espresso coffee), using the machine described, is as follows.

The machine is loaded by removing the hermetic-closure cap or lid of the supply duct to allow the infusion liquid (water) to be loaded into the boiler reservoir, then the cap or lid is placed back in place to ensure an airtight seal.

A similar operation is required to load the coffee, which occurs by opening the access door to the infusion tank, depositing the ground coffee and finally closing the same door. A collecting container such as a cup or small cup is arranged in correspondence with the dispensing nozzle, and the process of preparing the beverage is started through a switch activating an electric circuit powering the heating system of the boiler reservoir. A heating system timer activates the system for the time required to complete a beverage preparation cycle. The infusion liquid is heated until it reaches its boiling point, and due to the temperature increase, the air contained inside the boiler reservoir expands, assisted by the water vapor released by the boiling liquid. The infusion liquid is thus pushed, by the increasing pressure, through the collecting portion 20a of the transport duct, where it is blocked by the pressure release valve 30 until the pre-set or proper calibration pressure of the valve is reached. When the valve is released, the infusion liquid flows along the cooling portion of the duct, where it cools, and flows into the infusion tank 14 at the desired temperature. The infusion is then collected in the dispensing duct and delivered through the nozzle directly into the consumer's cup.

A second embodiment of the machine of the invention is shown by way of example in Figures 4a to 7c. This is an alternative configuration, adapted to traditional domestic extraction appliances of the thermo-mechanical type, such as for example the moka pot, which can thus reach operating temperature and pressure values higher than those currently envisaged.

Figures 4a and 4b are views of the machine or appliance in an assembled condition, while Figures 5a and 5b, 6a-6c and 7a-7c are views of the main components of the machine, i.e. of the boiler reservoir, of the infusion tank and of the collecting reservoir.

Similarly to a traditional moka pot, the machine of the invention comprises a boiler reservoir 12 within which the infusion tank 14 is partially housed, and a collecting container 18 can be coupled by means of a thread to said boiler reservoir, hermetically closing through the interposition of gaskets.

The boiler reservoir 12 has an overall truncated-conical or truncated-pyramidal shape surmounted by a collar 12b adapted to form a support seat for the infusion tank 14. A safety valve is provided, although not shown.

The infusion tank 14 has a traditional funnel shape from the base of which emerges a tubular formation 20a intended to be immersed in the chamber 12a of the boiler reservoir to operate as a collecting portion of the heated infusion liquid. The tubular formation 20a houses a pressure release valve 30. Unlike the infusion tank of a traditional moka pot, however, the collecting portion 20a of the infusion liquid is not placed in direct fluid communication with the infusion tank, but with a first interstitial cavity 40' formed in the body of the infusion tank 14, more particularly in the thickness of the circumferential or perimeter wall of the infusion tank. Said first interstitial cavity 40' has the shape of one or more radial channels, a circumferential cavity or a gyroid. A corresponding first interstitial cavity 42', also having the shape of one or more radial channels, a circumferential cavity or a gyroid, is formed integrally in the body of the wall of the collecting reservoir, placed in communication with the cavity 40' when the collecting reservoir is assembled to the boiler reservoir, holding the infusion tank in place. This first interstitial cavity 42' extends for example preferably for the entire height of the wall of the collecting reservoir, and at its top it joins a second interstitial cavity 42", for example coaxial to it, in turn placed in communication with a corresponding second interstitial cavity 40" of the infusion tank, which finally opens into the chamber of the tank where the powder substance is contained, through flow-dividing means 34. The set of the first and second interstitial cavities of the infusion tank and of the collecting reservoir constitutes the portion 20b for heat exchange, and therefore for cooling, of the duct transporting the infusion liquid. The infusion tank communicates, through filtering means 22, with a beverage dispensing duct 16, arranged axially to the collecting reservoir and having the shape of a chimney; said beverage dispensing duct has at least one dispensing hole 16a at its top, which opens into chamber 18a of the collecting reservoir.

The first interstitial cavities 40', 42' and the second interstitial cavities 40" and 42" form respectively the ascending and descending portions of the duct transporting the heated infusion liquid, which constitute the cooling portion.

In that case, the preparation procedure and the operating process of the machine are identical to those of a traditional moka pot. According to the operation of the traditional moka pot, when an energy source heats a wall of the boiler reservoir (for example, the lower wall in the case of a stove-top), the heat is yielded to the infusion liquid loaded in the chamber of the boiler reservoir and partially to the air present in the chamber. This may take place since said boiler reservoir is able to absorb thermal energy from a stove top or from an associated heating base, or to develop thermal energy by induction from a stove top or from an associated heating base with which it comes into contact through a wall of the chamber adapted to contain the infusion liquid to be heated-.

The expansion of the air and the evaporation of the boiling infusion liquid increase the pressure, thus the infusion liquid is forced to rise from the collecting portion of the transport duct. When the pressure reaches the calibration pressure value of the pressure release valve, the liquid is released into the first interstitial cavity 40' of the infusion tank, and from this to the first interstitial cavity 42' obtained in the wall of the collecting reservoir - which therefore fulfills, at the same time, the purpose of heat exchanger.

Advantageously, the geometry of the heat exchanger is adaptable according to the dissipation values to be desirably achieved.

The infusion liquid flows through the first interstitial cavities 40 'and 42' rising along the body of the machine, and then re-descends through the second interstitial cavities 42" and 40" and, crossing the dividing means 34, flows into the chamber 14a of the infusion tank containing the powder substance e.g. coffee. Through the filtering means 22 the infusion rises up the chimney of the delivery duct 16 and reaches the delivery holes 16a, flowing into the collecting reservoir 18.

Advantageously, in a currently preferred embodiment, the collecting reservoir is provided with circumferential grooves and projections on the wall’s outer face adapted to increase the total dissipation surface.

Similarly, the portion of the transport duct for cooling the infusion liquid, i.e. the interstitial cavities, have a plurality of formations protruding into the volume of the respective cavity crossed by the infusion liquid, adapted to increase the heat exchange surface.

In a currently preferred embodiment, the interstitial cavities and the external face of the wall of the collecting reservoir have topological characteristics, adapted to increase the dissipation surface, having more complex shapes than those mentioned here by way of example; for instance, these topologies can be derived from the TPMS (Triply Periodic Minimal Surface) functions already mentioned, and therefore have a gyroscopic conformation (or other TPMS). The structures depicted are representative and non- exhaustive simplifications of the possible geometric configurations.

In both embodiments, the invention achieves its aims due to the design possibilities offered by additive manufacturing or 3D printing technology. The increasing availability of materials, as well as the production costs’ reduction, today make it possible not only an indirect use of technology, such as the possibility of having complex functional prototypes in very competitive times and costs or the possibility of producing complex (and more performing) molds for traditional production processes, but also make a direct use of technology economically possible for a direct "printing" of the product or a part thereof. In such a scenario, it will be possible to customize the product according to specific needs, even those of individual consumers. In detail, by varying the geometry of the heat exchanger according to the main volumetric parameters (quantity of water - i.e. volume of the chamber of the boiler reservoir - and quantity of coffee - i.e. volume of the infusion tank) and the calibration pressure values of the valve, it will be possible to offer a customization of the extraction process that reflects consumers’ preferences (for example by delivering an "American"-type, or "moka"-type or "espresso"-type coffee, or other combinations). In addition, such a custom-made model opens up to significant aesthetic customization, including single product personalisation. By defining the extraction characteristics of the machine according to the preferences of the individual consumer, including the quantity of coffee, the quantity of water, as well as the desired extraction pressure, it will be possible to produce, starting from any contour- shape, geometries that (depending on the material used) provide a total dissipative capacity capable of guaranteeing that the temperature of the infusion liquid, upon percolation, is always within optimal values. The block diagram of figure 8 illustrates in detail a method for the production of a machine or appliance according to the invention through the use of an additive manufacturing technology, in particular for the design and production of the cooling portion of the infusion liquid. In a first step 100 the boundary shape (or volumetric constraint) of the heat exchanger or heat sink circuit and the desired thermal properties of said boundary shape, i.e. its heat dissipation capacity, are fed into a processor. In a second step 110, a plurality of predetermined three-dimensional geometric structures (reticular structures), including triply periodic minimal surfaces, and a plurality of materials are provided in a database accessible by the processor, where each combination of reticular structure-material is associated with a geometry and the thermal properties of said geometry made of said material.

In a third step 120 the processor divides said contour shape into a plurality of adjacent work cells, and in a fourth step 130 populates said work cells with at least one reticular structure available in the database, said reticular structure being selected:

(i) based on the correspondence of its thermal properties with the desired thermal properties of said contour shape; And

(ii) based on the compatibility of said reticular structure with any other possible reticular structure selected to populate one or more said adjacent elementary work cells.

Finally, at step 140 said contour shape bearing said reticular structures is produced, by means of an additive manufacturing technology (for example: Selective Laser Sintering, SLS, or Binder Jetting, BJ)

It should be noted that the embodiment proposed for the present invention in the preceding discussion has a purely illustrative and non-limiting nature for the present invention. A person skilled in the art will be able to easily implement the present invention in different embodiments which do not depart from the principles set out here, and are therefore included in the present patent.

This is particularly true with regard to the possibility of making the machine or appliance with a boiler reservoir which has a plurality of separate non-communicating chambers suitable for containing a respective infusion liquid to be heated, and with an infusion tank which comprises a plurality of separate compartments adapted to receive a predetermined quantity of a respective powder substance, each compartment of the infusion tank communicating with a corresponding chamber of the boiler reservoir, through a respective duct for transporting the heated infusion liquid, comprising its own valve means as well as a cooling portion of the infusion liquid having a respective preset geometric extension which determines its heat dissipation capacity, and including pressure release valve means arranged upstream of the cooling portion of the infusion liquid, having their own pre-set opening value.

Advantageously, this machine or appliance also comprises a plurality of beverage dispensing ducts each independently communicating with a respective compartment of the infusion tank. Alternatively, the different infusions are mixed and dispensed in a single delivery duct where they converge at different pressures and temperatures.

Of course, the principle of the invention remaining the same, the embodiment and details of construction may be widely varied with respect to what has been described and illustrated purely by way of non-limiting examples, without thereby departing from the scope of protection of the invention defined by the appended claims.

Claims

1. A household machine or appliance for preparing hot beverages by infusion or percolation, comprising a body which includes: a boiler reservoir having at least one chamber adapted to contain an infusion liquid to be heated; at least one infusion tank adapted to receive a predetermined quantity of powder substance; and at least one dispensing duct for the beverage obtained from the infusion of said powder substance; wherein the infusion tank communicates on one side with the boiler reservoir through at least one transport duct for the heated infusion liquid and on the other side with the beverage dispensing duct through filtering means adapted to retain the powder of the substance subject to infusion, wherein said transport duct for the heated infusion liquid comprises a collecting portion of the infusion liquid immersed in the chamber of the boiler reservoir and a cooling portion for the infusion liquid, characterized by the fact that said cooling portion for the infusion liquid is integrally formed in at least one wall of the machine body or in a supporting structure of the machine, or constitutes at least part of a wall of the machine body or of a supporting structure of the machine, which wall or supporting structure is in a heat exchange relationship with the external environment, and in that pressure release valve means are arranged along the transport duct for the infusion liquid, upstream of the cooling portion for the infusion liquid.

2. Machine or appliance according to claim 1, wherein said cooling portion for the infusion liquid includes a conduit shaped according to a triply periodic minimal surface.

3. Machine or appliance according to claim 1 or 2, wherein said wall or supporting structure in heat exchange relationship with the external environment has an open triply periodic minimal surface towards the external environment.

4. Machine or appliance according to any one of the preceding claims, wherein said boiler reservoir has a plurality of separate, non-communicating chambers adapted to contain a respective infusion liquid to be heated, and said infusion tank comprises a plurality of separate compartments adapted to receive a predetermined amount of a respective powder substance; each compartment of the infusion tank communicating with a corresponding chamber of the boiler reservoir through a respective transport duct for the heated infusion liquid comprising a cooling portion for the infusion liquid having a predetermined mass and respective surface extension per unit volume which determine the heat dissipation capacity thereof, said transport duct including pressure release valve means arranged upstream of the cooling portion for the infusion liquid, having a respective opening pressure value.

5. Machine or appliance according to claim 4, comprising a plurality of beverage dispensing ducts, in which each compartment of the infusion tank communicates with a respective dispensing duct of said plurality of beverage dispensing ducts.

6. Machine or appliance according to any one of the preceding claims, wherein the body of the machine includes a casing defining a housing volume of said boiler reservoir and said infusion tank, and said portion of the transport duct for cooling the infusion liquid is obtained integrally in the body of a wall of said casing.

7. Machine or appliance according to any one of the preceding claims, wherein the body of the machine includes an infusion liquid supply duct, in communication with said boiler reservoir, and said portion of the transport duct for cooling the infusion liquid is formed integrally in the body of a wall of said infusion liquid supply duct.

8. Machine or appliance according to any one of claims 1 to 4, wherein the body of the machine further includes a collecting reservoir which has at least one chamber adapted to receive the beverage produced by passing the hot infusion liquid through the powder substance, and said portion of the transport duct for cooling the infusion liquid is formed integrally in the body of a wall of the chamber of the collecting reservoir.

9. Machine or appliance according to any one of the preceding claims, in which the shape and dimensions of said cooling portion for the infusion liquid are configured and made in a customized way in a production step of the machine or appliance according to predetermined thermodynamic balances of expected temperature of the infusion liquid and calibration pressure of said pressure release valve means, depending on the volume of the chamber of the boiler reservoir and on the volume of the infusion tank.