Patent Description:
Automatic coffee machines capable of preparing both espresso beverages obtained at high pressure with cream formation and "drip" or American coffee beverages obtained at low pressure without cream formation are known.

In general, such coffee machines are provided with an infusion circuit having in cascade a water tank or a connection to a water source, a water supply pump, a boiler and an infusion unit where a dose of coffee powder is positioned. The document <CIT> discloses a coffee extraction method and a coffee machine performing such method.

The water that the pump draws from the tank or from the water mains is heated by the boiler and supplied to the infusion unit where it extracts the aromatic substances from the coffee powder.

For the espresso coffee beverage to be prepared throughout the infusion time, the dose of coffee is pressed inside the infusion chamber of the infusion unit and the coffee beverage leaving the infuser passes through a cream frother valve whose purpose is to increase the outlet pressure of the coffee beverage so as to generate turbulences in the flow, with consequent formation of air bubbles and foam.

For the "drip" coffee beverage to be prepared throughout the infusion time, the dose of coffee is not pressed inside the infusion chamber of the infusion unit and the coffee beverage leaving the infuser by-passes the cream frother valve.

In the coffee sector, the appreciation of other types of coffee beverages is spreading among consumers, including the so-called "cold brew" coffee.

"Cold brew" coffee is a type of beverage that requires the consumer to add ice cubes to the product dispensed in the cup until the desired result is obtained.

The organoleptic properties of "cold brew" coffee depend significantly on the extraction temperature.

Generally, coffee machines currently on the market for the preparation of a "cold brew" coffee are not able to control the process variables, with consequent deterioration of the organoleptic properties of the product in the cup.

In addition, the coffee machines currently on the market for the preparation of a "cold brew" coffee exhibit a lack of versatility in use as they are not able to customize the product dispensed. The technical task of the present invention is to overcome the drawbacks complained of by the prior art.

As part of this technical task, an object of the present invention is to realize a coffee extraction method and a coffee machine by means of which a variety of coffee recipes can be made while always ensuring the desired organoleptic properties of the product in the cup.

Another object of the present invention is to realize a coffee extraction method and a coffee machine by means of which both espresso coffee and "drip" coffee and "cold brew" coffee can be prepared.

The technical task, as well as this and other objects are achieved by the present invention which discloses a coffee extraction method with a coffee machine according to claim <NUM>.

Preferably an instantaneous boiler is employed as the electric heater.

Preferably said coffee machine conveys said heat regulation water flow in sequence at least through said electric heater and said infusion unit.

Preferably said coffee machine detects said temperature value at an inlet or an outlet of said electric heater.

In one embodiment of the invention said coffee machine performs said heat regulation step by activating said electric heater for heating said heat regulation water flow only if said detected temperature value is lower than said initial coffee extraction temperature of the selected coffee extraction cycle.

In one embodiment of the invention, at least one coffee extraction cycle envisages the activation of said electric heater throughout said extraction step for the maintenance of said initial extraction value during said extraction step.

In one embodiment of the invention, at least one coffee extraction cycle envisages the deactivation of said electric heater throughout said extraction step.

In one embodiment of the invention at least one extraction cycle envisages an initial extraction temperature value equal to room temperature.

In one embodiment of the invention at least one extraction cycle envisages an initial extraction temperature value comprised between <NUM> and <NUM>.

The present invention also discloses a coffee machine according to claim <NUM>.

In one embodiment of the invention said infusion circuit further comprises a coffee infusion dispensing conduit, a first connection conduit between a delivery of the supply pump and an inlet of the electric heater, a second connection conduit between an outlet of the electric heater and an inlet of the infusion unit, a valve unit, a third connection conduit between an outlet of the infusion unit and an inlet of the valve unit, said valve unit being configured to provide a first outlet path at high pressure comprising a back pressure means and a second outlet path at low pressure comprising a bypass means selectively activatable by the electronic controller for bypassing the action of said back pressure means and making the beverage pass into said second outlet path.

In one embodiment of the invention said first connection conduit, said electric heater, said second connection conduit, said infusion unit, said third connection conduit and said valve unit are connected to be crossed in sequence by said heat regulation water flow.

According to the invention the extraction of "cold brew" coffee at the desired temperature can be obtained, since the preliminary control and regulation of the temperature of the components of the infusion circuit through the heat exchange due to the heat regulation water flow is added to the control and to the regulation of the temperature of the infusion water.

In the preferred solution, the heat regulation water flow is disposed of through the discharge conduit, but it is not ruled out that it can be disposed of through the infusion dispensing conduit in such a way as to have a substantial homogenization of the temperature along the entire hydraulic circuit before the extraction step is performed.

In this regard, it should also be noted that the adoption of an instantaneous boiler as an electric heater, otherwise known as a "flow through heater", greatly facilitates obtaining the initial extraction temperature with a modest amount of heat regulation water.

The invention will be better illustrated by the description of a preferred embodiment thereof, given by way of non-limiting example, with reference to the following accompanying figures:.

With reference to the figures, the automatic coffee machine <NUM> comprises an electronic controller <NUM> and an infusion circuit that includes: a water source <NUM>, in the specific case a water tank, or a connection to a water source, for example a connection to the water mains; a supply pump <NUM>; an electric heater <NUM>, particularly an instantaneous boiler provided with one or more electric resistors <NUM>; a first connection conduit <NUM> between a delivery of the supply pump <NUM> and an inlet of the electric heater <NUM>; an infusion unit <NUM> provided with an infusion chamber <NUM> suitable for containing a dose of coffee powder to be infused, where the infusion chamber <NUM> has an inlet opening <NUM> and an outlet opening <NUM>; a second connection conduit <NUM> between an outlet of the electric heater <NUM> and the inlet opening <NUM> of the infusion unit <NUM>; a valve unit <NUM> provided with an inlet 31a and an outlet 31b; and a third connection conduit <NUM> between the outlet opening <NUM> of the infusion chamber <NUM> and the inlet 31a of the valve unit <NUM>.

The inlet opening <NUM> and the outlet opening <NUM> of the infusion chamber <NUM> are preferably made one on a fixed body <NUM> and the other one on a movable piston <NUM>.

The infusion circuit further comprises a dispensing valve <NUM> placed upstream of the inlet opening <NUM> of the infusion chamber <NUM>, configured to keep the inlet opening <NUM> of the infusion chamber <NUM> closed until the supplied water exceeds a certain pressure value, and open it upon exceeding this value.

By way of example, the dispensing valve <NUM> can be configured to counteract a maximum pressure of about 3bar, preferably comprised between <NUM> and 3bar.

The dispensing valve <NUM> may also be configured to act as a non-return valve, so as to prevent a retrograde flow from the infusion chamber <NUM>.

The valve unit <NUM> downstream of the infusion chamber <NUM> is configured to define a first outlet path <NUM> at high pressure and a second outlet path <NUM> at low pressure.

The inlet 31a of the valve unit <NUM> is connected to the outlet opening <NUM> of the infusion chamber <NUM> and the outlet 31b of the valve unit <NUM> is connected to a beverage dispensing conduit <NUM> in turn connected to a dispensing nozzle <NUM> by means of which the coffee infusion can be dispensed into a container <NUM>.

The valve unit <NUM> comprises a back pressure means <NUM> adapted to provide a certain back pressure force and a bypass means <NUM> selectively activatable to bypass the action of the back pressure means <NUM>.

In the solution illustrated by way of example, the path at high pressure <NUM> and the path at low pressure <NUM> are respectively defined by a first branch <NUM> and by a second branch <NUM>, which are distinct from each other and which extend between the inlet 31a and the outlet 31b.

According to such an embodiment, the back pressure means comprises a cream frother valve <NUM> arranged along the first branch <NUM> and configured to allow the beverage to pass through it only if the pressure exceeds a defined threshold value.

By way of example, the cream frother valve <NUM> can be configured to counteract a maximum pressure of about 3bar, preferably comprised between <NUM> and 3bar.

The bypass means may comprise a shut-off valve <NUM> arranged along the second branch <NUM> that can be selectively controlled to open or close a passage conduit and allow, or respectively prevent, the beverage to pass therethrough.

The shut-off valve <NUM> may be, for example, a solenoid valve.

The coffee machine <NUM> also has a special sensor means <NUM> of a temperature along the infusion circuit, preferably placed upstream or, as shown, downstream of the electric heater <NUM> and in particular between the electric heater <NUM> and the infusion unit <NUM>.

A flowmeter <NUM> may also be provided along the infusion circuit, preferably placed upstream of the supply pump <NUM>.

The machine <NUM> may also comprise a self-triggering valve <NUM> arranged along a conduit <NUM> placed downstream of the pump <NUM> and in derivation with the first connection conduit <NUM>.

The self-triggering valve <NUM> can be made as a sleeve valve, or a "pinch" valve.

Finally, the machine <NUM> also comprises a discharge conduit <NUM> for the residual water deriving from the exhausted coffee powder.

The discharge conduit <NUM> may be made in derivation of the dispensing conduit <NUM> and be kept normally closed by means of a discharge solenoid valve <NUM> arranged along it.

The coffee extraction method is as follows.

The electronic controller <NUM> has in memory a plurality of coffee recipes and an association to each recipe of a corresponding coffee extraction cycle executable from the coffee machine.

Each coffee extraction cycle advantageously comprises in sequence an infusion circuit heat regulation step, a step of introducing the dose of coffee powder into the infusion chamber <NUM>, and a step of extracting coffee having an initial coffee extraction temperature value Ti (where i=<NUM>, <NUM>, <NUM>,.

The electronic controller <NUM>, after having acquired from the consumer, for example through a machine/user interface, a selection of a recipe, performs the extraction cycle associated therewith.

In practice, the electronic controller <NUM> acquires the temperature value T detected by the sensor means <NUM>, compares the temperature value T detected with the initial extraction temperature value Ti of the selected extraction cycle, and performs the heat regulation step by activating the supply pump <NUM> for generating a heat regulation water flow until the value T of the detected temperature achieves the initial extraction temperature value Ti of the selected extraction cycle. The heat regulation water flow flows at least through the main components of the infusion circuit, in particular at least through the electric heater <NUM> and the infusion unit <NUM>.

Preferably, as shown, the first connection conduit <NUM>, the electric heater <NUM>, the second connection conduit <NUM>, the infusion unit <NUM>, the third connection conduit <NUM> and the valve unit <NUM> are connected to be crossed in sequence by the heat regulation water flow.

In the solution shown, the heat regulation water flow can be discharged through the discharge conduit <NUM> but it is not ruled out that it can be discharged through the dispensing conduit <NUM> to have greater temperature uniformity along the infusion circuit before starting the extraction step. For the execution of the heat regulation step, the electronic controller <NUM> activates the electric heater <NUM> for heating the heat regulation water flow if the value T of the acquired temperature is lower than the initial extraction temperature value Ti.

The electronic controller <NUM> can regulate the settings of the pump <NUM> and/or of the electric heater <NUM> so that the heat regulation water flow can quickly bring the value T of the temperature detected by the sensor means <NUM> to the initial extraction temperature value Ti.

When, as a result of the thermal exchange between the heat regulation water flow and the components of the infusion circuit, the value T of the temperature detected by the sensor means <NUM> is brought to the initial extraction temperature value Ti, the heat regulation step ends and the electronic controller <NUM> can control the execution of the step of introducing the dose of coffee powder into the infusion chamber <NUM> and then the execution of the extraction step. Advantageously, the various selectable recipes, and the extraction cycles associated therewith can also be programmable.

Depending on the recipe, the extraction cycles may differ, in addition to the initial extraction temperature value Ti, also in the time trend of the temperature during the extraction step and/or in the trend of the pressure along the infusion circuit also during the extraction step.

Some extraction cycles associated with recipes that can be performed by the coffee machine are shown below.

The heat regulation step depends on the initial extraction cycle temperature value T1 in turn depending on the recipe.

The initial extraction cycle temperature value T1 is set at <NUM>, i.e. at room temperature.

The infusion unit <NUM> has the infusion chamber <NUM> empty, the exhausted coffee powder having previously been expelled.

The infusion chamber <NUM> then connects the second connection conduit <NUM> to the third connection conduit <NUM>.

When acquiring the recipe and identifying the associated extraction cycle, the electronic controller <NUM> opens the shut-off valve <NUM> to allow bypassing the cream frother valve <NUM> and opens the discharge solenoid valve <NUM> to allow the discharge of water.

The electronic controller <NUM> acquires the value T of the temperature detected by the temperature sensor means <NUM> and, if the acquired value T is higher than the initial extraction cycle value T1, then it keeps the electric heater <NUM> deactivated but it activates the pump <NUM> which draws water generally at room temperature from the tank <NUM> or from the water network so as to generate a heat regulation water flow that flows through the infusion circuit and cools it.

The electronic controller <NUM> deactivates the pump <NUM> for interrupting the heat regulation water flow when it acquires a temperature value T equal to the initial extraction cycle temperature value T1.

At this point the heat regulation step ends.

The electronic controller <NUM> does not intervene on the shut-off valve <NUM> which remains open but it controls the closing of the discharge solenoid valve <NUM> in order to connect the infusion unit <NUM> to the dispensing conduit <NUM>.

The electronic controller <NUM> controls in sequence the opening of the infusion chamber <NUM>, the loading of the dose of coffee powder, and the closing of the infusion chamber <NUM> without compression of the dose of coffee powder.

At this point the extraction step begins.

The electronic controller <NUM> controls the activation of the pump <NUM> and keeps the electric heater <NUM> deactivated.

Infusion takes place by keeping the shut-off valve <NUM> open and the discharge solenoid valve <NUM> closed.

The pump <NUM> can be controlled continuously or by pulses depending on the type of aroma to be obtained, in any case guaranteeing a pressure around <NUM> bar.

Depending on the recipe selected through the machine/user interface, an amount of ice to be added to the product in the cup is recommended.

In this way a "cold brew" coffee of the classic type can be obtained.

The extraction cycle is indicated by the letter A in <FIG>, where the x axis shows the time and the y axis the temperature detected by the sensor means <NUM>, and where t<NUM> indicates the instant in which the temperature regulation step ends and the extraction step begins.

Case <NUM> differs from case <NUM> in that the initial extraction cycle temperature value T2 is set between <NUM> and <NUM>.

The electronic controller <NUM> acquires the value T of the temperature detected by the temperature sensor means <NUM> and, if the acquired value T is lower than the initial extraction cycle value T2, then controls the activation of the electric heater <NUM> as well as of the pump <NUM> which draws water generally at room temperature from the tank <NUM> or from the water mains so as to generate a heat regulation water flow that, after being heated by the electric heater <NUM>, flows through the infusion circuit and heats it.

The electronic controller <NUM> deactivates the pump <NUM> and the electric heater <NUM> when it acquires a temperature value T equal to the initial extraction cycle temperature value T2.

The electronic controller <NUM> activates the pump <NUM> and the electric heater <NUM>.

The pump <NUM> can be controlled by the electronic controller <NUM> continuously or by pulses depending on the type of aroma to be obtained, in any case guaranteeing a pressure around <NUM> bar. The electric heater <NUM> is controlled by the electronic controller <NUM> in such a way as to keep substantially at the value T2 the temperature detected by the sensor means <NUM> throughout the extraction step.

In this way another type of "cold brew" coffee can be obtained.

The extraction cycle is indicated by the letter B in <FIG>, where t<NUM> still indicates the instant in which the heat regulation step ends and the extraction step begins.

Case <NUM> differs from case <NUM> in that the initial extraction cycle temperature value T3 is set between <NUM> and <NUM>.

When acquiring the recipe and identifying the extraction cycle associated with it, the electronic controller <NUM> opens the shut-off valve <NUM> to allow bypassing the cream frother valve <NUM> and opens the drain solenoid valve <NUM> to allow the discharge of water.

The electronic controller <NUM> acquires the value T of the temperature detected by the temperature sensor means <NUM> and, if the acquired value T is lower than the initial extraction cycle value T3, then controls the activation of the electric heater <NUM> as well as of the pump <NUM> which draws water generally at room temperature from the tank <NUM> or from the water mains so as to generate a heat regulation water flow that, after being heated by the electric heater <NUM>, flows through the infusion circuit and heats it.

The electronic controller <NUM> deactivates the pump <NUM> and the electric heater <NUM> when it acquires a temperature value T equal to the initial extraction cycle temperature value T3.

The electronic controller <NUM> activates the pump <NUM> but keeps the electric heater <NUM> deactivated. Infusion takes place by keeping the shut-off valve <NUM> open and the discharge solenoid valve <NUM> closed.

The pump <NUM> can be controlled by the electronic controller <NUM> continuously or by pulses depending on the type of aroma to be obtained, in any case guaranteeing a pressure around <NUM> bar. Since the electric heater <NUM> is deactivated, during delivery the detected temperature T will gradually move towards room temperature.

The extraction cycle is indicated by the letter C in <FIG>, where t<NUM> still indicates the instant in which the heat regulation step ends and the extraction step begins.

Case <NUM> differs from case <NUM> in the extraction step which is performed with the shut-off valve <NUM> closed so that the first outlet path <NUM> at high pressure is selected in place of the second outlet path <NUM> at low pressure.

All the extraction cycles set out above may involve drying the exhausted dose of coffee by squeezing it. In particular, the electronic controller <NUM> can order a relative movement of approach between the piston <NUM> and the body <NUM> and the liquid extracted from the exhausted dose of coffee can be conveyed to the discharge conduit <NUM> simply by switching the discharge solenoid valve <NUM>.

The coffee machine <NUM> can perform in a versatile manner extraction cycles also of other types, for example an extraction cycle that envisages a compression of the dose of coffee between the piston <NUM> and the body <NUM> of the infusion chamber <NUM>, and the execution of the extraction step with an initial cycle value Ti between <NUM> and <NUM> maintained throughout extraction step, with a pump operating at high pressure, for example at least <NUM> bar, and a shut-off valve <NUM> closed for extracting an espresso coffee.

More generally, in at least one extraction cycle it can be provided for the extraction step to take place with the electric heater <NUM> activated for the maintenance of the initial extraction temperature, as illustrated for example in cases <NUM> and <NUM> set out above, or for the extraction step to take place with the electric heater <NUM> deactivated for the gradual descent of the initial extraction temperature, as illustrated for example in cases <NUM> and <NUM> set out above.

Finally, according to the invention it is possible to envisage the automatic execution of a coffee machine sanitizing cycle, where the supply pump <NUM> is activated with the electric heater <NUM> activated and the infusion chamber <NUM> is empty for circulating water at a high temperature, for example between <NUM> and <NUM>, along the infusion circuit.

The electronic controller <NUM> of the coffee machine may be programmed to automatically execute a sanitization cycle at each coffee machine switching on and/or if an extraction cycle at high temperature, for example <NUM> and <NUM>, has not been selected for a number of consecutive times.

Claim 1:
A coffee extraction method with a coffee machine (<NUM>) comprising an infusion circuit at least including a water tank (<NUM>) or a connection to a water source, a supply pump (<NUM>), an electric heater (<NUM>) and an infusion unit (<NUM>) having an infusion chamber (<NUM>) where a dose of coffee powder can be positioned, connected in sequence,wherein said machine stores a plurality of selectable extraction cycles each including in sequence an infusion circuit heat regulation step, a step of introducing said dose into said infusion chamber (<NUM>), and a step of extracting coffee having an initial coffee extraction temperature value (Ti), and in that at least one extraction cycle envisages the extraction step with an initial extraction temperature value (Ti) equal to room temperature and with said electric heater (<NUM>) deactivated, characterized in that, after acquiring a selection of a coffee extraction cycle, the coffee machine (<NUM>) detects the value (T) of a temperature along the infusion circuit, compares said detected temperature value (T) with the initial extraction temperature value (Ti) of the selected extraction cycle, and performs the heat regulation step by activating the supply pump (<NUM>) to generate a heat regulation water flow in the absence of said dose of coffee in said infusion chamber (<NUM>) until said detected temperature value (T) achieves said initial extraction temperature value (Ti) of the selected extraction cycle.