Patent Description:
As is well known, the preparation of espresso coffee requires a predetermined amount of hot water to be forced at high pressure through the pressed coffee powder, also known as coffee tablet. While passing through the coffee powder, the water extracts the aromatic substances, forming the coffee drink. In general, then, espresso coffee machines include a boiler (or heating unit) to heat water, a dispensing unit capable of holding a filter containing the pressed coffee powder, and a pump suitable for feeding hot water to the dispensing unit at a sufficiently high operating pressure (usually about <NUM> bar) to allow an adequate flow of water through the coffee tablet.

Around this basic structure, various types of machines have been developed which, in order to better adapt to specific needs, differ in the technical solutions used. Within the general scope of espresso coffee machines, in fact, various more specific categories can be identified, for example according to the intended use (professional or domestic), according to the market range (entry level, medium range or high range) or even according to the prevailing tastes of the target market. Each of these factors may suggest the adoption of a specific technical solution among some equivalent solutions.

In particular, there are manual machines called lever or press machines in which the operating pressure of the water is generated manually by the operator through the action of a lever, possibly combined with a spring.

In other machines, however, the working pressure required to push water through the coffee powder is obtained by means of an electric pump (typically a solenoid pump).

Again, in some machines the flow of hot water from the boiler to the dispensing unit is controlled by a manual control (not to be confused with the press lever) with which the operator defines the timing of the operation. The progenitor of this type of machine is the famous Faema E61. In other machines, however, the flow of hot water is controlled by one or more solenoid valves that can be controlled by an electromechanical or, more commonly, electronic control unit. The development of the latter type of machines has gradually led to the automation of the preparation of espresso coffee, with enormous benefits in terms of repeatability of results.

Recently, manually operated machines have experienced a new success linked to the rediscovery of traditions and a taste for vintage, also thanks to the adoption of captivating aesthetic solutions. The present invention finds a particularly advantageous use in such manually operated machines, although it can also be used in other types of machines.

Within the preparation of espresso coffee briefly described above, there are numerous variations that give rise to coffees with different characteristics, for example in terms of volume, aroma, quality and quantity of the cream. Among the known brewing techniques, one which is particularly appreciated, is the one which provides for the so-called pre-brewing phase. In accordance with this practice, once the hot water is fed to the dispensing unit and has completely wet the coffee tablet, the water supply is momentarily suspended, thus introducing a slight delay in the actual brewing. This pre-brewing delay, of the order of <NUM>-<NUM> seconds, has the effect of allowing the coffee powder to absorb the water and swell slightly, further increasing the compactness of the tablet. This increased compactness prevents the water, fed at operating pressure, from finding preferential paths within the coffee tablet. Such paths would lead to an excessive extraction in some areas of the tablet and, consequently, to an incomplete extraction in other areas of the tablet. Pre-brewing, on the other hand, allows for optimal extraction and, all other factors being equal, a much better quality of espresso coffee.

This pre-brewing technique is obtained in a way known per se with programmable machines, in which the control given by the operator activates the electronic control unit which can be programmed at will to control various devices such as pumps and solenoid valves, so as to perform various sequences of operations. Specifically, following a single control given by the operator, the electronic control unit first activates the electric pump to start feeding water to the tablet so as to wet it. Then the electronic board suspends the water supply for a few seconds, for example by suspending the operation of the pump or by closing a solenoid valve along the supply pipe. Finally, the electronic board resumes normal water supply with predefined pressure and flow rate, in order to obtain the coffee drink.

It is also feasible to apply the pre-brewing technique with a non-programmable machine, for example with a manually operated machine. In this case, the operator shall modulate the movement of the manual control, in order to obtain the pre-brewing delay. However, such a way of proceeding is based solely on the skills, sensitivity and experience of the operator and therefore requires a long learning phase. This is inconvenient because throughout the learning phase the results obtained by the operator cannot be optimal. In addition, this technique does not allow for the repeatability of results that is required for professional use.

There is therefore a need to be able to employ the pre-brewing technique with adequate repeatability of results, even with non-programmable machines.

Patent document <CIT> discloses a water boiler for dispensing units of espresso coffee machines.

The object of the present invention is to overcome the drawbacks of the prior art.

In particular, a task of the present invention is to make available a non-programmable espresso machine that enables the application with adequate repeatability of the pre-infusion technique.

Again, a task of the present invention is to make available a method for the brewing of espresso coffee that allows the pre-brewing technique to be applied with adequate repeatability even with non-programmable machines.

These and other objects and tasks of the present invention are achieved by means of a machine and a method for brewing espresso coffee incorporating the characteristics of the attached claims, which form an integral part of this description.

In accordance with a first aspect, the invention relates to an espresso coffee machine whose dispensing unit comprises a dispensing chamber in connection with a filter for containing a tablet of pressed coffee powder. The dispensing unit also comprises a pre-brewing chamber in connection with the dispensing chamber, in which the pre-brewing chamber comprises a movable wall configured to allow a variation of the internal volume of the pre-brewing chamber as a function of a force exerted on the movable wall by a pressurized liquid. The machine also comprises a pump for supplying pressurized hot water to the dispensing unit; a manual control to operate the pump; a dispensing valve to control the entry of hot water into the dispensing chamber; and a drain valve to control the water outlet from the dispensing unit. The same manual control configured to operate the pump is configured to also control the dispense valve and the drain valve.

Advantageously, the movement of the movable wall, conditioned by the flow of water to the pre-brewing chamber, determines a temporary limitation of the increase in water pressure inside the dispensing chamber. In this way, the water pressure in this phase, substantially around the activation pressure, does not reach sufficient values to cause the water to pass through the tablet. The time it takes for the water to completely fill the pre-brewing chamber and thus allow the pressure to rise to operating pressure is the desired pre-brewing delay, which allows the coffee powder to become sufficiently wet and swell before the water flows through it.

Preferably, the movable wall of the pre-brewing chamber is movable between a rest position and a working position and vice versa, and the pre-brewing chamber comprises thrust means configured to push the movable wall towards the rest position in contrast to the force exerted on the wall mobile.

Preferably, the movable wall comprises stop means which define the working position of the movable wall itself, and the stop means are adjustable.

Preferably, the force exerted by the thrust means on the movable wall in the rest position is adjustable.

Preferably, the pump is configured to supply water at an operating pressure of about <NUM>-<NUM> MPa and with a flow rate of at least <NUM> cc/min.

In accordance with a second aspect, the invention relates to a method for infusing espresso coffee, comprising the steps of:.

Preferably, the flow rate of water fed to the dispensing unit is a continuous, uninterrupted and/or substantially constant flow rate of water over time.

Preferably the different steps of directing the flow of hot water are achieved by arranging fluid paths offering different and progressive resistances.

Further characteristics and objects of the present invention will become more apparent from the following description.

The invention will be described below with reference to some examples, provided for explanatory and non-limiting purposes, and illustrated in the attached drawings. These drawings illustrate different aspects and embodiments of the present invention and, where appropriate, reference numerals illustrating similar structures, components, materials and/or elements in different figures are indicated by similar reference numerals. Also, for clarity of illustration, some references may not be repeated in all figures.

While the invention is susceptible to various modifications and alternative constructions, some preferred embodiments are shown in the drawings and will be described below in detail. It must be understood, however, that there is no intention of limiting the invention to the specific embodiment illustrated, but, on the contrary, the invention is intended to cover all modifications, alternative constructions, and equivalents that fall within the scope of the invention as defined in the claims.

The use of "for example", "etc.", "or" indicates non-exclusive alternatives without limitation unless otherwise indicated. The use of "comprises" and "includes" means "comprises or includes, but not limited to" unless otherwise indicated.

The invention is intended to be used in the presence of gravity acceleration g. In the following discussion it is understood that the acceleration of gravity g uniquely defines the vertical direction and, consequently, the horizontal directions. Furthermore, it is considered that based on the acceleration of gravity g the terms "high", "above", "higher" and the like are uniquely defined with respect to the terms "low", "below", "lower" and the like.

With "manual control" reference is made to a control that does not include the intermediation of any programmable electronic or electromechanical device. Specifically, the manual control in a coffee machine allows the operator to act directly on the valves and on the pump drive.

In accordance with a first aspect, the invention relates to an espresso coffee machine, indicated with <NUM> in the attached figures.

The machine <NUM> according to the invention comprises a dispensing unit <NUM> comprising a dispensing chamber <NUM> in fluid connection with a filter <NUM> configured to contain a tablet <NUM> of pressed coffee powder. The dispensing unit <NUM> further comprises a pre-brewing chamber <NUM> in fluid connection with the dispensing chamber <NUM>, wherein the pre-brewing chamber <NUM> comprises a movable wall <NUM> configured to allow a variation of the internal volume of the pre-brewing chamber <NUM> as a function of a force exerted on the movable wall <NUM> by a liquid fed to the pre-brewing chamber <NUM>.

Machine <NUM> in accordance with the invention also includes:.

In the machine <NUM> in accordance with the invention, the same manual control <NUM> configured to operate the pump <NUM> is configured to also control the dispensing valve <NUM> and the drain valve <NUM>.

Preferably, the movable wall <NUM> of the pre-brewing chamber <NUM> is movable between a rest position R and a working position L and vice versa. In the rest position R the movable wall <NUM> defines the minimum internal volume of the pre-brewing chamber <NUM>, while in the working position L the movable wall <NUM> defines the maximum internal volume of the pre-brewing chamber <NUM>. Preferably, the pre-brewing chamber <NUM> further comprises thrust means <NUM> suitable to push the movable wall <NUM> towards the rest position R. The thrust means <NUM> therefore oppose the movement of the movable wall <NUM> towards the working position L.

Advantageously, the movable wall <NUM> comprises stop means <NUM> which define the stroke end and therefore the working position L of the movable wall <NUM> itself. Preferably, the stop means <NUM> are adjustable in such a way as to be able to adjust the overall stroke of the movable wall <NUM>.

In accordance with the embodiments of the attached figures, the thrust means <NUM> comprise elastic means, in particular a spring, which push the movable wall <NUM> towards the rest position R. In accordance with other embodiments (not shown) the movable wall <NUM> and the relative thrust means <NUM> can assume a different structure. For example, the movable wall <NUM> can be arranged for a translation which develops at least partially vertically, in which the rest position R is lower than the working position L, and in which the thrust means <NUM> comprise a weight which acts by gravity on the movable wall <NUM>.

In accordance with some embodiments, the force exerted by the thrust means <NUM> on the wall in the rest position R is adjustable. For example, the elastic thrust means <NUM> may comprise a preload adjustment.

The force exerted by the thrust means <NUM> on the movable wall <NUM> in the rest position R, in relation to the useful area of the movable wall <NUM> itself, defines the activation pressure of the pre-brewing chamber <NUM>. As the skilled person may well understand, by useful area of the movable wall <NUM> it is meant the measure of its projection onto a plane perpendicular to the direction along which the movable wall <NUM> itself moves.

Advantageously, the dispensing unit <NUM> further comprises a drain <NUM>, in fluid connection with the dispensing chamber <NUM>. Preferably, the drain <NUM> is positioned in a lower part of the dispensing unit <NUM>.

The operation of the dispensing unit <NUM> of the machine <NUM> in accordance with the invention, and in particular of the pre-brewing chamber <NUM>, will be described in detail later.

The espresso coffee machine <NUM> according to the invention comprises a dispensing valve <NUM> which controls the entry of hot water into the dispensing chamber <NUM> and a drain valve <NUM> that controls the exit of water from the drain <NUM> at the end of the brewing process. In the embodiment of <FIG>, the drain valve <NUM> includes, in a per se known manner, two shutters acting in series along the drain <NUM>.

In a per se known manner, the machine <NUM> includes a hot water circuit <NUM> that ensures the supply of water at a predetermined temperature (usually about <NUM>) and in an amount appropriate for the intended use of the machine <NUM>. The hot water circuit <NUM> may take on different configurations depending on the types of machine <NUM>, but typically includes a boiler <NUM> and a chamber, referred to as thermosyphonic chamber <NUM>, located immediately upstream of the dispensing valve <NUM>. The thermosyphonic chamber <NUM> is advantageously configured to promote spontaneous circulation of hot water to and from the boiler <NUM>, such that water is constantly present at the desired temperature.

In a per se known manner, the pump is configured to supply water at an operating pressure and flow rate suitable for the preparation of coffee and other hot drinks. According to an embodiment, the pump <NUM> is configured to supply water at an operating pressure of about <NUM>-<NUM> bar (i.e. about <NUM>-<NUM> MPa) and with a flow rate suitable for the brewing of coffee drinks, for example a flow rate of at least <NUM> cc / min. Preferably the hot water pump <NUM> is an electric pump, for example a solenoid pump. The pump <NUM> is operated by the operator through the manual control <NUM>. The dispensing unit <NUM> according to the invention is in fact particularly suitable for the machines <NUM> with manual control, although it can also be applied to other types of machines <NUM>, including those press but also electronic and automatic ones.

The same manual control <NUM>, which activates the water pump <NUM>, also controls the dispensing valve <NUM> and the drain valve <NUM>. For example, if the manual control <NUM> is of the well-known lever type, the machine <NUM> can comprise one or more cams <NUM> suitable for controlling the two valves <NUM> and <NUM>. In particular, along the stroke that is imposed on the lever to operate the pump <NUM>, the lever itself moves the cam <NUM> which controls in the correct sequence the opening and closing of the two valves <NUM> and <NUM>.

The attached <FIG> show the dispensing unit <NUM> of a machine <NUM> in accordance with an embodiment of the invention in subsequent configurations of use. The attached <FIG> schematically show the dispensing unit <NUM> and some parts of the espresso machine <NUM> in accordance with an embodiment of the invention. The operation of the dispensing unit <NUM> and of the espresso coffee machine <NUM> is described in detail below with particular reference to these figures.

<FIG> and <FIG> show a waiting situation, wherein the machine <NUM> is ready to dispense a dose of coffee drink <NUM>. The filter <NUM> comprises a tablet <NUM> of pressed coffee powder, the dispensing unit <NUM> is empty, while the hot water, coming from the special supply circuit <NUM>, fills the thermosiphonic chamber <NUM> and slowly circulates inside it. In the simplified diagram of <FIG>, the thermosiphonic chamber <NUM> also comprises a plunger which represents the pump <NUM>. This diagram, however, has only an illustrative purpose, while the construction diagram of the actual machine <NUM> may be different. For example, in <FIG> only the thermosiphonic chamber <NUM> is represented because the pump <NUM> is a distinct element. In the waiting situation of <FIG>, the dispensing valve <NUM> is closed, while the drain valve <NUM> is open. In the waiting situation of <FIG>, the dispensing valve <NUM> and the drain valve <NUM> are both closed. In the absence of any external force, the thrust means <NUM> keep the movable wall <NUM> of the pre-brewing chamber <NUM> in the rest position R. In <FIG>, a cup <NUM> has been arranged to collect the coffee drink <NUM>.

<FIG> and <FIG> schematically show a step in the process of dispensing a dose of coffee. The dispensing valve <NUM> is open while the drain valve <NUM> is closed. As the skilled person may well understand, the hot water begins to follow the fluid path that leads it to fill the dispensing chamber <NUM> and to reach the filter <NUM>, in order to wet the coffee tablet <NUM>. Since this path offers minimal resistance, the water can travel along it with a negligible pressure, for example that present in the circuit <NUM>, even regardless of the action of the pump <NUM>. Consequently, in this initial step, the movable wall <NUM> of the pre-brewing chamber <NUM> remains in its own rest position R due to the action of the thrust means <NUM>.

<FIG> and <FIG> schematically show a subsequent step of the process of dispensing a dose of coffee. Under the action of pump <NUM>, hot water follows the fluid path that offers less resistance. Tablet <NUM> is made up of very fine, pressed coffee powder. Therefore, while being permeable, it offers great resistance to water. Without having an easy path available, the water increases its pressure due to the action of the pump <NUM>. Before reaching the operating pressure (i.e. the pressure level necessary to cross the coffee tablet <NUM>), the pressure of the water reaches the activation pressure of the pre-brewing chamber <NUM>, that is, it manages to overcome the action of the thrust means <NUM> on the movable wall <NUM>. Then the movable wall <NUM> moves from the rest position R towards the working position L, offering the water a path with a lower resistance than that which crosses the tablet <NUM>. In this way the internal volume of the pre-brewing chamber <NUM> gradually increases, gradually accepting a predetermined volume of water. <FIG> show an intermediate step in which the pre-brewing chamber <NUM> is partially filled, while <FIG> and <FIG> show a final step in which the pre-brewing chamber <NUM> is completely filled with water. The displacement of the movable wall <NUM> and the flow of water to the pre-brewing chamber <NUM> allow to temporarily limit the increase in the pressure of the water inside the dispensing chamber <NUM>. Preferably, the water pressure in this step remains substantially constant, around the activation pressure. The time taken by the water to completely fill the pre-brewing chamber <NUM> constitutes the desired pre-brewing delay, which allows the previously wet coffee powder to swell. In fact, during this time the water does not have a sufficient pressure to pass through the tablet <NUM> and therefore goes towards the pre-brewing chamber <NUM>.

<FIG> and <FIG> show a further step in the process of brewing a dose of coffee. From the moment in which the movable wall <NUM> of the pre-brewing chamber <NUM> has reached its stroke end (<FIG> and <FIG>), the pressure in the water begins to increase again due to the action of the pump <NUM>. In particular, because there is no other outlet, the water increases its pressure up to the operating pressure, necessary to cross the coffee tablet <NUM> by now swollen by the water that had reached it previously during the initial dispensing step. In this step, therefore, the water passes through the tablet <NUM> and the actual dispensing of the coffee drink <NUM> takes place, which is collected by gravity in the cup <NUM>.

<FIG> schematically shows a step of restoring the dispensing unit <NUM>. As can be seen, with respect to <FIG>, the dispensing valve <NUM> is closed while the drain valve <NUM> is open, allowing excess hot water still filling the dispensing assembly <NUM> to drain by gravity. Furthermore, the exhausted coffee powder has been removed from the filter <NUM>, while the hot water, coming from the special supply circuit <NUM>, returns to fill the thermosiphonic chamber <NUM> upstream of the dispensing valve <NUM>.

<FIG> and <FIG> schematically show a subsequent step of restoring the dispensing unit <NUM>. This step is very similar to that described above in relation to <FIG>, in which the dispensing valve <NUM> is closed and the drain valve <NUM> is open. An important difference concerns the pre-brewing chamber <NUM>. Thanks to the reduction of the water pressure, which vents outwards through the drain <NUM>, the thrust means <NUM> bring the movable wall <NUM> back to the rest position R, expelling the water from the pre-brewing chamber <NUM> and making it exit by gravity from the drain <NUM>.

<FIG> schematically shows a further step of restoring the dispensing unit <NUM>. As it can be seen, with respect to <FIG>, the dispensing chamber <NUM> and all the various ducts of the dispensing unit <NUM> are now empty, the drain valve <NUM> is closed and the thermosiphonic chamber <NUM> is progressively filling with hot water.

<FIG> schematically shows a waiting situation, in all respects similar to the initial one represented in <FIG>, in which the machine <NUM> is ready to dispense a dose of coffee. As can be seen, with respect to <FIG>, the coffee tablet <NUM> has once again been placed in the filter <NUM> and a cup <NUM> has once again been prepared to collect the coffee drink <NUM>.

In the light of the detailed description above, the skilled person will be able to better understand some technical features and their effects.

For example, the possibility described above of adjusting the length of the stroke of the movable wall <NUM> allows adjusting the time of the pre-brewing delay introduced in the dispensing of the coffee drink <NUM>. Preferably, this delay assumes a duration of about <NUM>-<NUM> seconds.

Advantageously, the thrust means <NUM> are sized so as to provide an activation pressure lower than the operating pressure. In particular, while the operating pressure is preferably between <NUM> and <NUM> bar, the activation pressure is preferably between <NUM> and <NUM> bar, even more preferably between <NUM> and <NUM> bar. The ability described above to adjust the force applied by the thrust means <NUM> to the movable wall <NUM>, allows adjusting the activation pressure, in order to better configure the machine <NUM> to the different conditions of use that may occur.

As the skilled person may well understand, the dispensing unit <NUM> can be used in various types of espresso coffee machines <NUM>. The most advantageous application is undoubtedly on the machines <NUM> with manual control <NUM> in accordance with the invention, since the dispensing unit <NUM> allows repeatable application of the pre-brewing technique even in the absence of any programmable device, such as an electronic control unit, to automatically introduce the pre- brewing delay in dispensing. However, the dispensing unit <NUM> can also be used in different machines <NUM>, for example in press machines as well as in other machines that employ an electric pump <NUM>. In any case, the machine <NUM> of the invention allows the pre-brewing delay to be obtained mechanically rather than by means of a specific programming of the operation.

In accordance with a second aspect, the invention relates to a method for brewing a coffee drink <NUM>. The method includes the steps of:.

Preferably, the water flow fed to the dispensing unit <NUM> is a continuous and uninterrupted water flow. Preferably, the flow of water fed to the dispensing unit <NUM> is a substantially constant water flow over time.

Furthermore, as the skilled person may well understand in the light of the above description, the different steps of directing the flow of hot water can be obtained simply by arranging fluid paths that offer different and progressive resistances. More specifically, at the beginning of the brewing, the dispensing chamber <NUM> and the ducts that connect it to the filter <NUM> are completely free from obstacles and therefore the hot water that is fed to the dispensing unit <NUM>, even at very low pressure, follows spontaneously this path, filling the dispensing chamber <NUM> and reaching the filter <NUM> and the coffee tablet <NUM>.

Subsequently, once the tablet <NUM> is wet, in a traditional method of the known type, the hot water should increase its internal pressure to the point of being able to pass through the coffee tablet <NUM>, which offers a very high resistance. The tablet <NUM> in fact is made up of very fine and pressed ground coffee powder, and therefore, although it is permeable, it offers a high resistance to water. Alternatively, in a known method that provides for the pre-brewing phase, the water flow would be suspended for a predefined time, thus introducing the pre-brewing delay.

Unlike what occurs in known methods, at this point of the method according to the invention, the flow of hot water does not undergo any interruption or decrease and is directed to the pre-brewing chamber <NUM>. By increasing its volume, the pre-brewing chamber <NUM> is able to accommodate a predetermined volume of water. Preferably, the step of directing the water flow to the pre-brewing chamber <NUM> includes the sub-steps of:.

The time taken by the hot water to completely fill the pre-brewing chamber <NUM> represents the desired pre-brewing delay during which the wet coffee powder can swell, further compacting the coffee tablet <NUM>.

Similarly to what is described above, the step of directing the water flow back to the filter <NUM> includes the sub-steps of:.

As the skilled person can well understand from the description above, the different steps of directing the flow of hot water can be obtained without the use of solenoid valves or other similar devices, therefore without actually closing any ducts.

As the skilled person may well understand, the invention overcomes the drawbacks highlighted above in relation to the prior art.

In particular, the invention makes available a non-programmable espresso coffee machine <NUM> that allows the pre-brewing technique to be applied with adequate repeatability.

Furthermore, the invention makes available a method for infusing espresso coffee that allows the pre-brewing technique to be applied with adequate repeatability even with non-programmable machines.

Finally, all the details can be replaced by other technically equivalent elements.

Claim 1:
Espresso coffee machine (<NUM>), comprising:
- a dispensing unit comprising a dispensing chamber (<NUM>) in fluid connection with a filter (<NUM>) configured to contain a tablet (<NUM>) of pressed coffee powder, wherein the dispensing unit (<NUM>) further comprises a pre-brewing chamber (<NUM>) in fluid connection with the dispensing chamber (<NUM>), and wherein the pre-brewing chamber (<NUM>) comprises a movable wall (<NUM>) configured to allow a variation of the internal volume of the pre-brewing chamber (<NUM>) as a function of a force exerted on the movable wall (<NUM>) by a fluid fed to the pre-brewing chamber (<NUM>);
- a pump (<NUM>) configured to feed hot water under pressure to the dispensing unit (<NUM>), where the fluid fed to the pre-brewing chamber (<NUM>) is hot water;
- a manual control (<NUM>) configured to operate the pump (<NUM>);
- a dispensing valve (<NUM>) configured to control the entry of hot water into the dispensing chamber (<NUM>); and
- a drain valve (<NUM>), configured to control the outlet of water from a drain (<NUM>) of the dispensing unit (<NUM>);
characterized in that the same manual control (<NUM>) configured to operate the pump (<NUM>) is configured to also control the dispensing valve (<NUM>) and the drain valve (<NUM>).