IT202100007517A1 - PROFESSIONAL MACHINE FOR THE PREPARATION OF ESPRESSO COFFEE - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

PROFESSIONAL COFFEE PREPARATION MACHINE? EXPRESSED

TECHNICAL FIELD OF THE INVENTION

The present invention ? relating in general to machines for the preparation of beverages, in particular hot beverages obtained by infusing substances from infusion with pressurized hot water, such as coffee-based beverages, for example coffee espresso, coffee instant coffee long or fresh-brew, etc., drinks based on tea, or drinks based on barley or other cereals.

The present invention finds advantageous, although not exclusive, application in professional machines for the preparation of coffee. espresso, automatic or semi-automatic, which the following discussion will do? reference for convenience? descriptive without losing in generality?.

STATE OF ART

How?? known, the coffee? is experiencing great interest from the public and the hotel industry sector, also known as Ho.Re.Ca., acronym of Hotellerie-Restaurant-Caf?). The interest in this drink is growing transversally among consumers, the signs dedicated to the taste and experience of this drink are multiplying, and this despite the crises that have followed. Indeed, consumption in the last 40 years has gone from 80 to 160 million bags of coffee? from 60 kg and also the millennials contribute to this growth, both in traditional markets and in less mature ones where the coffee segment? ? created from scratch in regions such as China or the Far East.

Today? The accent of the sector? on premiumization, that is? the trend of consumers to purchase products at a higher price level, and on specialties, while espresso accounts for 10% of the business of the large chains.

In the field of professional machines for preparing coffee? espresso, are there different technologies to control the coffee infusion process? in order to ensure good quality of the product dispensed.

Some of these technologies are for example described in EP 1867 262 B1, EP 2 313 182 B1, EP 2313 183 B1, EP 2575561 B1, EP 2642 906 B1, EP 2991 530 B1, EP 3 364 826 A1, WO 2015/124592 A1 and US 2015/110935 A1.

In particular, WO 2015/124592 A1 describes a coffee machine? comprising at least one hydraulic infusion circuit comprising at least one water feed pump, at least one boiler hydraulically connected in cascade to the feed pump, at least one infusion unit hydraulically connected in cascade to the boiler and which can be crossed by a flow of hot water for the execution of a brewing cycle, means for regulating the water flow, means for measuring the water flow, and a feedback controller connected to the regulating means and the measuring means and configured to compare in real time the current value of the water flow measured by the measuring means with a corresponding reference value and piloting the regulating means in such a way as to cancel any deviation of the current value of the water flow from the corresponding reference value of the water flow.

US 2015/110935 A1 does it concern the regulation of the flow rate in a coffee machine? expressed, during a multi-phase infusion process including a pre-infusion phase and an extraction phase. During the pre-infusion phase, the coffee ground is slowly pre-wetted and/or degassed with a first volume of water delivered at a first flow rate. During the extraction phase, a second volume of water is dispensed at a second flow rate greater than the first flow rate and at a pressure generally greater than the pressure with which the first volume is dispensed, to extract the coffee. expressed. Are the flow rates, volumes and pressures regulated by the coffee machine? espresso, which comprises a flow rate adjustment assembly comprising first and second paths and first and second valves. Bartenders can vary the flow rate, volume and pressure of the water during the brewing process by opening, closing or otherwise regulating at least one of the valves.

Has the Applicant been able to ascertain that the professional machines for the preparation of coffee? expressed described in the previous? listed above, although they are satisfactory in many respects, still have ample room for improvement in terms of control of the coffee infusion process, which is a fundamental factor for the quality? of the drinks dispensed.

For this purpose, in WO 2021/005570 A1 the Applicant has proposed a machine for preparing beverages comprising at least one brewing unit for producing a beverage by infusion of a substance to be infused with an infusion liquid, a supply circuit of a liquid of infusion to the brew group, and a unit? electronic control of? operation? of the machine for making a drink (1). The infusion liquid feeding circuit includes a solenoid valve that regulates the flow of the infusion liquid fed to the brew group, and a volumetric counter for the quantity of infusion liquid. of infusion liquid fed to the brew group.

The unit control electronics? electrically connected to the volumetric meter to receive the electric output supplied by this, and to the flow regulator solenoid valve to supply it with an electric command, and is it? configured to memorize representative data of at least one target flow rate profile of the infusion liquid indicative of the temporal trend of the flow rate of the infusion liquid to be fed to the brew unit during a beverage preparation cycle, and to control in closed loop the ?flow regulating solenoid valve on the basis of the electrical output of the volumetric meter and the target flow rate profile of the infusion liquid in such a way as to make s? that the current flow rate of the infusion liquid fed to the brew group follows the target flow rate profile of the infusion liquid.

SUBJECT AND SUMMARY OF THE INVENTION

The Applicant has been able to ascertain that the beverage preparation machine described in WO 2021/005570 A1, although it is very satisfactory in many respects, also has a margin for improvement in terms of control of the coffee infusion process ?.

Purpose of the present invention? so to provide a professional machine for the preparation of coffee? improved espresso compared to those known in terms of control of the coffee infusion process.

According to the present invention there is provided a machine for preparing beverages, as claimed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1, 2 and 7-11 illustrate time profiles of physical quantities involved in the preparation of a beverage in a professional coffee machine. expressed.

Figures 3a, 3b and 3c schematically illustrate the pre-infusion, pressurization and actual infusion phases which make up a cycle for preparing a beverage.

Figure 4 shows a perspective view of a professional coffee making machine. expressed by the Applicant.

Figures 5, 6a and 6b schematically illustrate different hydraulic circuits and electronic control architectures of the operation of the professional machine for the preparation of coffee? expressed in Figure 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The present invention will be now described in detail with reference to the attached figures to allow an expert person to make and use it. Various modifications to the embodiments described will be immediately apparent to skilled persons and the generic principles described can be applied to other embodiments and applications without thereby departing from the protective scope of the present invention, as defined in the attached claims. Thus, the present invention is not to be considered limited to the described and illustrated embodiments, but is to be accorded a scope of protection consistent with the described and claimed features.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning commonly used by persons of ordinary experience in the field pertaining to the present invention. In the event of a conflict, this description, including any definitions provided, will binding. Furthermore, the examples are provided for illustrative purposes only and as such should not be considered limiting.

In particular, the block diagrams included in the attached figures and described below are not to be understood as a representation of the structural characteristics, or construction limitations, but must be interpreted as a representation of functional characteristics, properties? that is? intrinsic of the devices and defined by the effects obtained or functional limitations and which can be implemented in different ways, therefore in order to protect the functionalities? of the same (possibility? to work).

In order to facilitate understanding of the embodiments described herein, reference to some specific embodiments and a specific language sar? used to describe them. The terminology used in this document is intended to describe only particular realizations, and not ? intended to limit the scope of the present invention.

In summary, the present invention relates to a technology, hereinafter referred to by the term DFC, acronym for Dynamic Flow Control, for the dynamic regulation of the flow rate of the water fed to the infusion units of the professional coffee machine. espresso in order to dynamically modify the coffee dispensing conditions, consequently varying the properties? organoleptic characteristics of the product in the cup.

The DFC technology differs from other existing technologies based on the regulation of the water flow because? it does not impose a predefined water flow rate during the various phases of preparation of the drink following the pre-infusion phase of the substance to be infused.

In particular, the DFC technology arises from the Applicant's observation that there is no perfect water flow rate for all coffees: ? in fact, it is practically impossible to obtain two identical dispensing from two coffee tablets? also very similar, while maintaining the exact same water flow throughout the beverage preparation cycle and even if you can? try to reduce the pi? possible the variables in play that can modify the preparation conditions, these cannot be completely eliminated.

Grain size of the coffee? ground, amount of ground, distribution of the powder, compression force of this inside the filter holder, whether it is made with manual or dynamometric tampers, homogeneity? of the compression, etc., are variables that are not perfectly controllable even by the pi? experienced bartenders using the best equipment available. In these conditions of variability, imposing predetermined water flow rates throughout the supply can turn out to be counterproductive.

Consider for example the case in which, following the calibration of the coffee grinder? in granules, has it been found that the flow of water Q fed to a brew group during the preparation of the coffee? expressed is a well-identified function of time Q(t) or of the volume of water supplied, Q(v), or is even considered constant Q(t) = K or Q(v) = K from a certain moment onwards? delivery. Normally, therefore, Q ? definable as a flow of water which guarantees that the product in the cup satisfies the requirements (taste, body, quality of the cream) of the coffee. dispensed.

Technologies already? on the market try to regulate the water flow to exactly replicate the Q function, thus imposing pre-established operating conditions, without considering that the variables involved can make the result in the cup extremely inconstant. Does the Applicant have for? got to experience that in the event that, for example, the coffee tablet? compressed present in the filter holder contained a few tenths of a gram less than the quantity? nominal (error of the grinder), or that it was compressed not perfectly (human error), or that the coffee? ground coffee itself has different characteristics in terms of humidity, granulometry, composition, etc., while maintaining the same flow rate Q(t) or Q(v), the pressure inside the filter holder could vary considerably. A coffee pod? which tends to ?give? (for example due to the channeling effect, or because the coffee is excessively seasoned and is "consumed" quickly), opposes less resistance to the passage of water and the regulation system, to maintain the predetermined functions Q(t) or Q( v), acts by slowing down the flow of water which, on the other hand, would naturally tend to grow. In this way there is a risk of drastically reducing the dispensing pressure, bringing it to values completely outside the desired range and which guarantee the best extraction.

To visualize this phenomenon, Figure 1 illustrates, by way of example, a graph in which the following are displayed:

- Black curve (1): ? a typical optimal water flow curve, defined by the user and which would be replicated by normal water flow regulation systems for all coffees? supplied with that specific predefined characteristic.

- Green curve (2): ? the pressure of the water fed to the brew group in the optimal case Q(t), which would guarantee that the extraction of the coffee? reflects the organoleptic requirements, - Dashed red curve (3): ? the ?natural? water flow? that a coffee tablet? would let the water pass at constant pressure, as occurs in most coffee machines, with a single water pump, at constant water pressure given by the bypass of the water pump.

- Dashed blue curve (4): ? the water pressure that would naturally arise if the water flow regulation did not intervene.

- Continuous blue-red curve (5): ? the water pressure resulting from the regulation of the water flow.

How can you? appreciate by analyzing the graph, the water pressure (continuous blu-red curve) tends to drop significantly in the final delivery, why? the coffee tablet, yielding, opposes less resistance and the water flow regulation system? forced to intervene by reducing the flow of water. A dispensing of this type, despite having registered the same water flow rate Q(t) as in the optimal case, has a resultant water pressure and, therefore, also the result in the cup, completely different from the desired one.

The technologies that apply pure water flow control are in fact capable of faithfully replicating the Q(t) flow curve of the optimal case, but the water pressure in the various beverage preparations can vary a lot with respect to the optimal condition, because?, as yes ? said, the resistance that the coffee tablet? opposes the passage of water varies in a completely unpredictable way throughout the preparation of the drink and depends not only on the characteristics of the coffee? (grinding, pressing, blending, etc.), also by the pressure of the water fed to the brew group.

In conclusion, to maintain the water flow rate Q(t) at the pre-set value, the action of regulating the water flow rate inevitably affects the pressure of the water fed to the brew group, with the effect of compromising repeatability. of the results in the cup.

Therefore, has the Applicant had the opportunity to experience that ? it is preferable to work at a fixed water pressure, without any type of regulation of the same, to guarantee a result in the cup as quick as possible. similar to the optimal case, rather than perfectly replicating a water flow rate Q(t) curve, completely losing control over the water pressure. The professional coffee machines? traditional and without any regulation system, n? of pressure n? of water flow, in fact, are they able to maintain a good repeatability? of dispensing in the cup, with a certain tolerance due to the numerous variables involved, why? constructively, that is, with the bypass of the pump? water, eliminate, keeping it almost? constant, the variable of the pressure of the water, that ? very important for the result in the cup.

To there? is added the fact that in recent years? observed that the market is moving towards solutions that allow the user to personalize the drinks dispensed, towards greater flexibility? aimed at enhancing certain characteristics of the coffee? or to hide any defects. A customization of the drinks dispensed requires the possibility? to control easily measurable physical quantities during coffee delivery, such as, for example, pressure, temperature and flow rate.

As far as water flow control is concerned, the main problem is, how is it done? mentioned above, that the control of the flow of water alone cannot? ensure repeatability? of coffee extraction, given that the total loss of control over the pressure of the water fed to the brew group leads to extremely variable results in the cup. The necessity? to even make the reference profile of the water flow that the control system must reproduce customizable by the user, so as to be able to generate different reference profiles of the water flow Q1(t), Q2(t)? Qn(t), can? lead to completely uncontrollable results, thus leaving the main market demands: customization and repeatability.

DFC technology intends to solve the problem of customization and repeatability? giving the user a limited number of parameters to adjust and dynamically controlling the water flow, adapting the water flow profile to the conditions of the coffee pad. The DFC technology, in fact, does not define a correct water flow rate (which in fact does not exist, given the innumerable variables involved), but instead defines the water flow mode. of extraction.

The DFC technology, in fact, d? to? the user the possibility? to prepare the drink according to predefined criteria, leaving him the freedom to to modify its characteristics and to choose whether or not to keep the water flow rate constant in specific stages of preparation of the drink. In this way, the system becomes adaptable to the variables involved and, if it were required to keep the water flow rate constant, this would not be predefined by the user, given that, how is it? seen, there is no perfect water flow rate, but it would be calculated by the system at a particular moment in the preparation of the drink.

In professional coffee machines? traditional methods, eliminated the pre-infusion and water pressure variables and since the hydraulic characteristics of the water supply circuit to the brew unit are fixed, the water flow rate is ? determined exclusively by the conditions of the coffee pad? present in the filter holder. Can you? so to say that a professional coffee machine? The traditional method has only one way of extracting coffee: fixed pre-infusion, in terms of both duration and water flow rate, and constant water pressure.

The DFC technology belongs to this category, but with the possibility? to change the methods? of preparation of the drink, acting in the three main phases of the same: pre-infusion, pressurization, infusion.

Figure 2 illustrates typical time profiles of water pressure (blue curve) and water flow rate (black curve) in a professional coffee machine. traditional.

In Figure 2, the three main stages of preparing a drink are also identified with rectangles:

- Pre-infusion (left box): the water fed to the filter holder percolates at low pressure from the shower and begins to wet the upper layers of the tablet. The flow rate of the water? almost constant and depends exclusively on the hydraulic characteristics of the water supply circuit;

- Pressurization (central box): has water filled the space between the coffee pod? and the shower and find the resistance of the coffee tablet, which in the meantime is getting wet and swelling inside the filter holder. The water pressure in the infusion chamber increases and the water flow reaches a maximum peak, and then starts to drop when the volume between the hand shower and the filter holder is reduced. completely saturated with the extracted beverage. The water flow rate then reaches a minimum (brewing chamber completely saturated, carbon dioxide emission and crema formation) and the water pressure reaches maximum levels. From this moment on, the drink comes out of the filter holder and is served in the cup. In a traditional machine, since? the water pump works at a fixed pressure, pressurization always occurs at the same speed;

- Infusion (right panel): the coffee? it comes out of the spouts of the filter holder and ends up in the cup; after having reached the minimum that identifies the completion of the pressurization, does the water flow rate grow slightly, the coffee tablet? it tends to wear out by modifying the resistance it opposes to the flow of water, until the end of delivery. In traditional machines, the pressure of the water? constant while the flow of water depends only on the conditions in which the coffee pod is found at that moment? wet.

DFC technology makes it possible to modify the three phases of preparation of the drink by intervening on a few characteristic parameters of the three phases themselves:

- Pre-infusion:

? Flow with which to start wetting

? Duration

- Pressurization:

? Speed? of pressurization (slope of the pressurization ramp) - Infusion:

? Stabilized flow infusion

? Free flow infusion

Once the method of preparation of the drink has been defined, determined by the combination of parameters that can be modified by the user, and the water pressure has been fixed via the bypass of the water pump, the result in the cup will have a repeatability? quite similar to that of the traditional ones.

The three phases of preparation of the drink mentioned above are discussed in detail below with reference to the professional machine for preparing coffee. expressed in Figure 4 and a block diagram of which ? shown in Figure 5.

As illustrated in Figures 4 and 5, the professional machine for preparing coffee? express, indicated as a whole with the number 1, includes:

- one or more infusion units 2 suitable for carrying out the same infusion process of a substance to be infused, in this case in the form of coffee powder, with an infusion liquid, in this case in the form of pressurized hot water, to produce the same beverage of coffee?, in this case coffee? expressed, in quantity? identical or different, for example coffee? small or long espressos, starting with coffee powder of the same or different typology in terms of coffee species? (arabica, robusta), coffee blend?, coffee granulometry?, treatment to which the coffee? ? been subjected, for example decaffeinated, flavored, etc.;

- a water supply circuit 3 to feed the brew groups 2 with the pressurized hot water necessary for the preparation of the coffee? expressed;

- a user interface 4 for each brew group 2 for the selection of drinks by a user; and

- a?unit? control electronics 5 to check the? operation? of the professional machine 1 for the preparation of coffee? expressed in response to a user's beverage selections.

Each brew group 2 includes:

- a pressurized hot water dispenser 6 in the form of a shower (?shower head?) or a sprayer (?sprinkler?), and

- a filter holder 7 equipped with one or more? 8 coffee dispensing nozzles? espresso and internally defining an infusion chamber suitable for containing, in use, coffee powder to infuse with pressurized hot water for the preparation of coffee? espresso and to be manually coupled, in use, to the pressurized hot water dispenser 6 to receive the pressurized hot water fed by this.

The water supply circuit 3 includes:

- a water pump 9, convenient a speed pump? electronically controlled variable, and in the illustrated non-limiting example unique for all brew groups 2, which ? hydraulically fed with cold water supplied by a cold water source (not shown) which can alternatively be constituted by the public water distribution network or by a water tank housed in, or external to and fluidly connected to, the professional machine 1 for preparing coffee? expressed and fluidly connected to the public water distribution network to receive cold water, and is it operable to feed pressurized cold water, e

- a water supply branch 10 for each brew group 2, arranged downstream of the water pump 9 and fluidically connected between the delivery of the water pump 9 and the respective brew group 2 to supply pressurized hot water to the respective brew group 2.

Optionally, the water supply circuit 3 could include a water pre-heater (not shown), conveniently of the continuous-flow pre-heater? type, located downstream of the water pump 9, between this and the water supply branches 10, to pre-heat the water fed to the latter.

Each water supply branch 10 comprises, in succession in the direction of water flow from the water pump 9 to the respective brew group 2:

- an electronically controlled water flow regulating solenoid valve 11 and, optionally, a giggleur 12 arranged upstream of the water flow regulating solenoid valve 11, to regulate the water flow in the water supply branch 10 ;

- a volumetric water meter 13, also known under the name of volumetric water flow meter, for measuring the, and outputting an electrical signal indicative of the quantity? of water, measured in volume, fed to the relative water supply branch 10; And

- a water heater 14 for (further) heating of the water in the water supply branch 10.

In a preferred embodiment, the water flow rate regulating solenoid valves 11 are motorized solenoid valves with step-by-step electric motors, so as to allow discrete regulation of the water flow rate.

In a different embodiment, the water flow rate regulating solenoid valves 11 could be motorized solenoid valves with linear electric motors, so as to allow substantially continuous regulation of the water flow rate.

The unit control electronics 5 ? electrically connected to the water volumetric meters 13 to receive the electrical signals indicative of the water flow rates in the respective water supply branches 10 generated by these, to the user interfaces 4 to receive electrical signals indicative of the beverage selections made, and to the water pump 9, to the water flow regulating solenoid valves 11, to the water heaters 14 and to the water pre-heater, if provided, to supply them with electrical control signals.

The unit control electronics 5 ? configured for:

- memorize functional data necessary to control the regulation system 11 of the flow rate of the infusion liquid fed to the brew unit 2 during a cycle of preparation of a beverage and such as to allow to determine the existence of one or different predefined characteristics of the liquid flow rate infusion system fed to the brewing unit 2 during a beverage preparation cycle;

- control the regulation system 11 of the flow rate of the infusion liquid fed to the infusion group 2 during a cycle of preparation of a drink on the basis of the memorized functional data and of the electrical output of the volumetric counter 13 so as to carry out a pre- -infusion of the substance to be infused with the infusion liquid in the infusion chamber, followed by a step of pressurizing the infusion chamber, and by a subsequent phase of infusion of the substance to be infused with the infusion liquid in the infusion chamber;

In a different embodiment, the professional machine for preparing coffee? espresso shown in Figure 4 could have a different water flow regulation architecture, whose simplified block diagram ? shown in Figure 6a. To allow for comparison with Figure 5, in Figure 6b ? Also illustrated is the water flow regulation architecture shown in Figure 5, but in the same simplified form as that of Figure 6a.

How can you? appreciate, while in the water flow regulation architecture illustrated in Figure 5 and 6b, ? Is there a single water pump common to all brew groups, with delivery pressure stabilized by the bypass circuit, as in common coffee machines? traditional, and a volumetric meter and a proportional motorized solenoid valve on each water supply branch which modifies the flow passage section, increasing the localized pressure drops and consequently varying the water flow rate, in the architecture of water flow adjustment shown in Figure 6a ? provided a water pump for each brew group and in which the regulation of the water flow? made through the regulation of the speed? of rotation of the water pump. For example, using a gear water pump, varying the speed? rotation of the drive motor, you can? increase or decrease the delivery pressure and consequently also the water flow rate. In this case, even if there were no upstream pressure stabilization by means of the bypass circuit, direct or indirect methods would be used to verify the working point of the water pump, so? to keep the dispensing pressure in the range foreseen for the dispensing.

Returning to the three phases of preparation of the drink mentioned above, they will be analyzed in detail below with reference to the water flow regulation architecture illustrated in Figure 6b, it being clear that how much is? valid, mutatis mutandis, also for the water flow regulation architecture illustrated in Figure 6a.

1. Pre-infusion

During the pre-infusion phase, the unit? control electronics 5 ? programmed to adjust the flow rate of the water fed to each brew group 2 in a closed loop by suitably controlling, conveniently using PID (Proportional-Integral-Derivative) control techniques, the relative water flow rate regulating solenoid valve 11 on the basis of the output of the relative water volumetric meter 13, so that the water flow rate regulating solenoid valve 11 introduces a localized pressure drop such as to reduce the water flow rate to the desired values.

In particular, the unit? control electronics 5 ? programmed to allow an operator to set the water flow rate to be fed to each brew group 2 and the duration of each pre-infusion phase, during which the water therefore comes out of the shower at an extremely limited flow rate compared to that which would be allowed by the hydraulic conditions. Having not yet encountered the resistance of the coffee tablet, without the aid of a pre-infusion chamber as occurs in traditional machines, the water comes out at atmospheric pressure and the water flow rate is ? determined exclusively by the load losses of the circuit, being the pressure of the water fed by the pump of the water 9 almost? constant.

The unit control electronics 5 ? programmed to adjust the flow rate of the water supplied to each brew group 2 in closed loop by following a target water flow profile indicative of the temporal trend of the water flow rate Q(t) that you want to be fed to the brew group 2 during the pre-infusion phase in a coffee-based beverage preparation cycle.

The unit control electronics 5 ? programmed to allow an operator to program, for each brew group, a pre-infusion water flow rate profile and a pre-infusion duration. Conveniently, but not necessarily, to simplify the programming of the pre-infusion phase, the unit? control electronics 5 ? programmed to allow an operator to select the pre-infusion water flow rate and the pre-infusion duration among different, for example three, constant pre-infusion water flow rates and pre-infusion durations stored in the unit? control electronics 5, as shown in Figure 7.

2. Pressurization

As previously said, in this phase the water has already met the coffee pad? and the filling of the infusion chamber (shower and filter holder) must be completed. The operator can? choose how quickly to bring the water pressure in the infusion chamber from the minimum levels assumed in the pre-infusion phase (close to atmospheric pressure) to the maximum supply pressure from the water pump.

The unit control electronics 5 ? therefore programmed to control each water flow regulating solenoid valve 11 in open loop to achieve the pressurization profile shown in Figure 8, ie without realizing any closed loop control of the water flow.

In particular, during the pressurization phase, the unit? control electronics 5 ? programmed to constantly monitor the water flow on the basis of the electrical output of the relative volumetric counter 13 and to determine when this has one or different predefined characteristics indicative of a condition of appropriate filling of the infusion chamber with the infusion liquid.

In a preferred embodiment, the unit? control electronics 5 ? programmed to determine the fact that the water flow has one or more? of the following predefined characteristics: assumes or is close to a maximum value, starts decreasing after having assumed a maximum value, and its derivative is within a predefined interval.

To do this?, the unit? control electronics 5 ? programmed to calculate the variation over time (discrete time derivative) of the water flow rate and to determine when the variation in the water flow becomes essentially equal to zero or is it within a certain variation range, for example ? below a certain variation threshold (? 0.2 ml/sec).

When the water flow assumes one or the different predefined characteristics described above, what? does it mean that the infusion chamber is ? completely filled and the water is passing through the holes in the filter, which introduce a further and significant pressure drop, so that the water flow rate begins to drop drastically and, therefore, the pressurization phase of the infusion chamber ends.

For simplicity? implementation, the? unit? control electronics 5 ? programmed to control the water flow regulating solenoid valve 11 via a PWM (Pulse Width Modulation) type control, which, how is it? known, causes the water flow regulating solenoid valve 11 to alternately close and open over time until the maximum water flow is reached, starting from which, until the end of the pressurization phase, the water flow regulating solenoid valve? water 11 is kept constantly open to a given passage section, conveniently the one assumed when the water flow takes on one or the different characteristics mentioned above, to allow the volumetric counter 13 to define without disturbances (the PWM pulsations introduce errors reading) the flow rate of? water that will be used? during infusion.

In a different embodiment, the unit? control electronics 5 could be programmed to control the water flow regulating solenoid valve 11, instead of? through a PWM-type control, through controls of different types, such as gradual openings according to otherwise defined curves and more? or less sophisticated, which always have the purpose of pressurizing more? or less quickly the infusion chamber, giving the operator the possibility? to choose between different possibilities?.

To this end, the unit? control electronics 5 ? programmed to allow an operator to program, for each brew group 2, a pressurization profile of the brewing chamber. Conveniently, but not necessarily, to simplify the programming of the pressurization phase, the unit? control electronics 5 ? programmed to allow an operator to select between three PWM levels in the initial ramp phase (increase in water flow), as illustrated in Figure 9, in which the passage section of the water flow regulating solenoid valve 11 which is maintained at the end of the pressurization phase? conveniently the same in all three tiers.

As ? It is possible to appreciate in Figure 9, the water pressure curves are approximated with straight lines. The different colors highlight how the pressurization after the pre-infusion takes place with ramps having a slope that is greater the more? high ? the PWM level attributed to the three different levels. The resulting water flows for the three PWM levels are shown in grey; clearly, more quick ? the pressurization of the infusion chamber, pi? quickly the water flow reaches the maximum.

3. Infusion

The two phases of preparation of the drink previously described, i.e. pre-infusion and pressurization, can be defined as preparatory phases, as the coffee tablet is wetted and pressurized. before the actual preparation and dispensing in the cup. This last phase of preparation of the drink, called infusion, in traditional machines generally takes place at constant water pressure, while the water flow rate that is determined therefore depends on how it is used. was the coffee tablet prepared? in the previous phases and by the pressure of the water pump.

Therefore, the unit? control electronics 5 ? programmed to allow an operator to customize the infusion phase by allowing him to choose between different modes? of infusion, conveniently, but not limited to, the following two described below.

3.1 Free infusion at constant water pressure

This mode? of infusion ? entirely equivalent, for the infusion phase only, to a traditional infusion, with a water pump that delivers water at a constant pressure defined by the bypass circuit of the pump itself. The flow rate of the water? left free and there are no interventions of the flow rate regulating solenoid valve 11, which remains open to a predetermined passage section.

3.2 Infusion at controlled water flow

At the end of the pressurization phase, as mentioned, the flow rate regulating solenoid valve 11 is found and is kept open at a predetermined passage section. Taking, for example, coffee? espresso, as seen previously, there is usually a minimum water flow rate when the water has completely filled the filter and the coffee is ready. emits a lot of carbon dioxide, forming cream. Subsequently, the coffee tablet? it begins to lose consistency as the water removes fats, proteins and all the substances that will make up the drink in the cup. Generally, there is a slight tendency for the water flow to increase (more noticeable in the case of more recently roasted coffees, less evident with very seasoned or old coffees).

Therefore, the unit? control electronics 5 ? programmed to allow an operator to choose this mode? of infusion, in which the infusion is completed with a water flow that has stabilized due to a progressive and gentle closure of the flow regulating solenoid valve 11. From the passage section assumed at the end of the pressurization phase, the? flow rate regulating solenoid valve 11 is controlled so as to make it perform slow closing movements, as long as? the flow of water remains increasing, so as to counteract the natural tendency of the flow of water to increase: in fact, more? the flow regulating solenoid valve 11 is closed, pi? this acts as a brake, introducing pressure drops which tend to slow down the flow of water.

Therefore, even during the infusion phase, the unit? control electronics 5 ? programmed to constantly monitor the water flow on the basis of the electrical output of the relative volumetric meter 13 and to determine when this has one or different predefined characteristics indicative of a stabilization of the water flow, in particular the variation over time (discrete time derivative ) of the water flow becomes substantially equal to zero or is it found within a specific range of variation, for example ? below a certain variation threshold (? 0.2 ml/sec).

When the flow of water assumes the moon or the different conditions indicated above, in particular yes? stabilized at a certain value, the? unit? control electronics 5 ? programmed to start controlling the water flow in closed loop using PID regulation techniques in order to try to maintain the last assumed value, as illustrated in Figure 10.

In essence, therefore, since? the coffee pads? compressed are always different from each other, the flow of water which is stabilized by the movements of the flow regulator solenoid valve 11 will be? yes always different, but sar? equal to that yes ? stabilized in the first part of the infusion phase, when the best parts of the coffee are extracted.

For how? was conceived, with the DFC technology the pressure of the water supplied to each brew group 2 will be? for most of the infusion phase at the pressure set by the bypass circuit of the water pump 9 and tender? slightly to decrease during the infusion. Prepare a coffee? with water pressure decreasing rather than fixed and with controlled flow pu? lead to change the result in the cup, for example by increasing the sweetness and reducing the bitter and astringent notes, which in traditional machines can be due to over-extraction of the coffee. in the last part of the infusion phase with constant water pressure.

Finally, given that for an operator unfamiliar with the layouts of the water flow curves Q(t) it could be very difficult to obtain useful information from reading these curves, the unit? control electronics 5 ? programmed to display on the user interface 4 of each brew group 2, during the preparation of a drink, the graph of the quantity? of water fed to the brew group 2 shown in Figure 11, where the slope with which this quantity? of water grows in the three phases of preparation of the drink described above (the amount of water is always increasing as it is accumulated) can? be easily controlled by the operator, and in which the three phases of preparation of the beverage described above are identified with different colours: Red for Pre-infusion, Orange for Pressurization and Yellow for infusion.

On the basis of what has been described above, the advantages that DFC technology allows to achieve are evident.

As mentioned initially, in fact, the main market demand? to be able to customize the preparation of coffee?, while maintaining the repeatability? of the result in the cup. In other words, a given beverage preparation profile, meaning by this term the water pressure profile or the water flow rate profile or even more? in general, the profile of a size that ? involved in the process of preparing a drink and which, when controlled, is able to guarantee certain results in the cup, must enhance certain characteristics of the coffee? served and these characteristics must be present in practically all coffee? disbursed with that particular profile.

The DFC technology, with a few parameters that can be modified by the operator, allows you to choose the mode? of preparation of the drink, ensuring flexibility? and repeatability.

In particular, as in traditional machines, also in DFC technology the bypass pressure of the water pump is ? The reference is fixed, but unlike traditional machines, the DFC technology allows for flexible and repeatable customization of the way in which the bypass pressure is reached in the infusion chamber and how coffee preparation is completed. In fact, once the bypass pressure of the water pump has been established, throughout the preparation of the coffee, the control system is completely independent from the water pressure, which in fact is not monitored in any way since no pressure transducer is installed.

Finally, in DFC technology, the pressure of the water supplied to each brew group is ? slightly waning during the infusion, thus allowing to increase the sweetness of the coffee? and reducing the notes of bitterness and astringency, which in traditional machines are caused by over-extraction of the coffee in the last part of the infusion phase at constant water pressure.

Claims (10)

1. Beverage making machine (1) including: - at least one infusion unit (2) configured to produce a drink by infusing a substance to be infused with an infusion liquid; - a supply circuit (3) of an infusion liquid to the brew unit (2); ed - a?unit? control electronics (5) to check l?operativit? of the machine for preparing a drink (1); the brew group (2) includes: - a dispenser (6) of an infusion liquid; And - a filter holder (7) equipped with one or more? delivery nozzles (8) of the beverage and internally defining an infusion chamber able to be filled, in use, with the infusion substance to be infused with the infusion liquid for the preparation of the beverage and to be manually coupled, in use, to the pressurized hot water dispenser (6) to receive the infusion liquid supplied by it; the supply circuit (3) of an infusion liquid comprises: - an adjustment system (11) of the flow rate of the infusion liquid fed to the infusion unit (2); And - a volumetric counter (13) to measure a quantity indicative of the quantity? of infusion liquid fed to the infusion unit (2) and supply an indicative electrical output of the quantity measured; the unit? control electronics (5) ? electrically connected to the volumetric counter (13) to receive the electrical output supplied by this, and to the regulation system (11) of the flow rate of the infusion liquid fed to the infusion group (2) to supply it with an electrical command; the unit? control electronics (5) ? configured for: - store functional data necessary to control the regulation system (11) of the flow rate of the infusion liquid fed to the brew group (2) during a beverage preparation cycle and such as to allow determining the existence of one or different predefined characteristics the flow rate of the infusion liquid fed to the brew unit (2) during a beverage preparation cycle; And - check the regulation system (11) of the flow rate of the infusion liquid fed to the brew group (2) during a drink preparation cycle on the basis of the memorized functional data and the electrical output of the volumetric meter (13) in such a way to carry out a pre-infusion phase of the substance to be infused with the infusion liquid in the infusion chamber, followed by a phase of pressurization of the infusion chamber, and by a subsequent phase of infusion of the substance to be infused with the infusion liquid in the infusion chamber; characterized by the fact that the unit? control electronics (5) ? also configured to carry out the pressurization phase of the infusion chamber by implementing the following operations: - check the regulation system (11) of the flow rate of the infusion liquid fed to the brew group (2) so as to cause a progressive increase in the flow rate of the infusion liquid fed to the brew group (2); - determine, on the basis of the electrical output of the volumetric counter (13), that the flow rate of the infusion liquid fed to the brew group (2) has one or different first predefined characteristics indicative of a condition of appropriate filling of the infusion chamber with the infusion liquid; And - when it is determined that the flow rate of the infusion liquid fed to the brew group (2) assumes one or the different first predefined characteristics, maintain the regulation system (11) of the flow rate of the infusion liquid fed to the brew group (2) in a predefined stationary operating state, so as to allow the flow rate of the infusion liquid fed to the brew unit (2) to evolve freely. 2. Beverage preparation machine (1) according to claim 1, wherein the unit? control electronics (5) ? also configured to cause a progressive increase in the flow rate of the infusion liquid fed to the infusion unit (2) during the pressurization phase of the infusion chamber by controlling the regulation system (11) of the flow rate of the infusion liquid fed to the infusion unit (2) in open loop. 3. Beverage preparation machine (1) according to claim 1 or 2, wherein the one or the different first predefined characteristics are defined by the fact that the flow rate of the infusion liquid fed to the brew unit (2) has one or more of the following characteristics: it assumes or is close to a maximum value, it begins to decrease after having assumed a maximum value, and its derivative is within a predefined interval. 4. Beverage preparation machine (1) according to any one of the preceding claims, wherein the unit? control electronics (5) ? configured to: - determine, on the basis of the electrical output of the volumetric counter (13), that the flow rate of the infusion liquid fed to the brew group (2) has one or different second predefined characteristics indicative of the existence of an appropriate condition for the ?beginning of the infusion phase of the infusion substance with the infusion liquid in the infusion chamber; And - when it is determined that the flow rate of the infusion liquid fed to the brew group (2) assumes one or the different second predefined characteristics, check the regulation system (11) of the flow rate of the infusion liquid fed to the brew group (2) so as to start the infusion step of the infusion substance with the infusion liquid in the infusion chamber. 5. Beverage preparation machine (1) according to claim 4, wherein the one or the different second predefined characteristics are defined by the fact that the flow rate of the infusion liquid fed to the brewing group (2) assumes or is close to or begins to stabilize at a minimum value during a decrease following the achievement of a maximum value. 6. Beverage preparation machine (1) according to any one of the preceding claims, wherein the unit? control electronics (5) ? it is also configured to carry out the infusion phase of the substance to be infused with the infusion liquid in the infusion chamber by implementing a mode? of infusion at controlled water flow including the following operations: - control the regulation system (11) of the flow rate of the infusion liquid fed to the brew unit (2) in such a way as to counteract the natural tendency of the flow rate of the infusion liquid fed to the brew unit (2) to increase; - determine, on the basis of the electrical output of the volumetric counter (13), that the flow rate of the infusion liquid fed to the brew unit (2) has one or different third predefined characteristics indicative of a stabilization of the flow rate of the infusion liquid fed to the unit infuser (2); - when the flow rate of the infusion liquid fed to the brew unit (2) assumes one or the different third predefined characteristics, control the regulation system (11) in closed loop of the flow rate of the infusion liquid fed to the brew unit (2) based on the electrical output of the volumetric counter (13) in such a way as to maintain the stabilized flow rate of the infusion liquid fed to the brew unit (2). 7. Beverage preparation machine (1) according to claim 6, wherein the unit? control electronics (5) ? also configured to counteract the natural tendency of the flow rate of the infusion liquid fed to the brew unit (2) to increase during the infusion phase of the substance to be infused with the infusion liquid in the infusion chamber by controlling the flow rate adjustment system (11) of the infusion liquid fed to the brew group (2) in an open loop. 8. Machine for the preparation of beverages (1) according to claim 6 or 7, wherein one or the different third predefined characteristics are defined by the fact that the variation of the flow rate of the infusion liquid fed to the brew group (2) is within a predefined range. 9. Beverage preparation machine (1) according to any one of the preceding claims from 6 to 8, wherein the unit? control electronics (5) ? also configured to allow an operator to customize the infusion phase of the substance to be infused, allowing him to choose between the aforementioned mode? of infusion at controlled water flow and a traditional modality? of free infusion at constant water pressure. 10. Machine for preparing beverages (1) according to any one of the preceding claims, wherein the system (11) for regulating the flow of the infusion liquid fed to the brew unit (2) comprises a flow regulating solenoid valve (11) electronically controlled or a feed pump (9) at speed? electronically controlled variable.