Espresso coffee machine with pre-infusion device with proportional valve and method for dispensing espresso coffee

Abstract

An espresso coffee machine is described comprising a coffee boiler configured to contain water, a dispensing group, and a hydraulic circuit between the coffee boiler and the dispensing group, wherein the dispensing group comprises an engaging member to engage in releasable manner a filter holder holding a filter with a coffee powder puck, wherein the hydraulic circuit comprises a first proportional two-way solenoid valve, and a second three-way solenoid valve that is arranged in the hydraulic circuit downstream of the first solenoid valve, and a flow measuring device for the water in the hydraulic circuit, the flow measuring device for water cooperating with the first solenoid valve.

Description

[0001] Espresso coffee machine with pre-infusion device with proportional valve and method for dispensing espresso coffee

[0002] TECHNICAL FIELD

[0003] The present invention relates, in general, to the field of espresso coffee machines. More specifically, it relates the pre-infusion step in espresso coffee machines.

[0004] Even more specifically, the present invention relates to an espresso coffee machine with a pre-infusion device comprising a proportional valve and a method for dispensing espresso coffee.

[0005] STATE OF THE ART

[0006] The conventional technique for extracting espresso coffee involves the entry of water into filter chamber in which the ground coffee is present. The water is introduced into the coffee by means of a pressure thrust which is generated either by means of a pump with an electric motor or by a mechanical-action pressure system (lever / piston / spring).

[0007] When the hot water reaches the coffee puck, a few problems may arise, these being mainly due to the speed of the flow and the sudden increase in pressure, which may result in a non-optimum extraction of the organic substances in the coffee.

[0008] Over time a number of so-called pre-infusion systems have been developed. The purpose of these systems is to introduce initially a smaller quantity of water inside the infusion chamber, at a lower pressure or lower flowrate. This operation ensures a more uniform distribution of water over all the ground coffee and avoids sudden increases in pressure and flowrate which occurs when there is no pre- infusion system. The result of this operation is a more homogeneous extraction which creates a more pleasant taste and tactile sensation on the palate, avoiding also the formation of channels in the coffee puck or cracking of the coffee puck which in any case result in non-uniform water flow passages.

[0009] Various pre-infusion systems are known.

[0010] According to a first known technique, dispensing is interrupted after a very short period of time, i.e. about one second, and then the initial dispensing is started again.

[0011] A second pre-infusion system is known from EP2299878 and involves introducing water very gradually into the pre-infusion chamber. This gradual supply is realized by using mechanical flow-restriction valves.

[0012] A third known pre-infusion system involves establishing pressure profiles which are managed electronically.

[0013] US2020170441 describes a coffee machine with a proportional pre-infusion system.

[0014] SUMMARY OF THE INVENTION

[0015] The Applicant has studied the known solutions to provide the pre-infusion function in an espresso coffee machine.

[0016] The Applicant has noted that the aforementioned first solution has at least two limitations: the first is that it cannot be carried out for a defined and manageable time, risking losing all the advantages by going into pressurized dispensing; the second is that it causes the discharge of part of the liquid containing extracted substances, and therefore reduces the quality of the extracted coffee.

[0017] The Applicant has noted that the second solution can also be improved because it can be difficult to find the manual adjustment point of the reduced flow to generate the correct infusion.

[0018] The Applicant has noted that the third solution is efficient but is still rather complex and expensive to implement.

[0019] According to the solution described in US2020170441 , the pre-infusion step is achieved by completely opening and closing the pre-infusion valve one or more times in a predetermined pre-infusion time. According to an exemplary embodiment described in US2020170441 , in a time of 5 seconds, the pre-infusion valve is opened to the maximum opening and then completely closed; subsequently, the pre-infusion valve is partially opened for a predetermined time and then closed.

[0020] The Applicant has set itself the objective of providing a different pre-infusion system not based on predetermined times but on the actual completion of the pre-infusion step.

[0021] The above objects are at least partially achieved by an espresso coffee machine with two solenoid valves in sequence: a two-way, proportional, solenoid valve upstream and a three-way solenoid valve arranged downstream of the two- way solenoid valve.

[0022] The combination of opening the solenoid valves allows water to be inserted into the infusion chamber at a pressure lower than the maximum dispensing pressure and, after the pre-infusion step has ended, provides for the actual dispensing to be carried out at the dispensing pressure (or maximum pressure).

[0023] According to the invention, the pre-infusion valve is kept partially open until the saturation (namely, until substantially complete filling) of the part of the circuit between the coffee powder puck in the filter and the pre-infusion valve. In this way, during the pre-infusion, the water from the coffee boiler reaches the coffee puck at a pressure that is lower than the pressure that can be dispensed during the dispensing of the espresso coffee. This is due to the fact that the proportional pre-infusion valve, during the pre-infusion step, is partially open. The water pressure will therefore be proportional to the opening degree of the pre-infusion valve.

[0024] At the end of the pre-infusion, namely, when the water at a pressure lower than the dispensing pressure has wetted the coffee puck and filled the empty space above the coffee puck and the circuit up to the pre-infusion valve, the pre-infusion valve opens completely so as to dispense the beverage, i.e. the espresso coffee.

[0025] According to a first aspect, the present invention provides an espresso coffee machine comprising a coffee boiler configured to contain water, a dispensing group, and a hydraulic circuit between the coffee boiler and the dispensing group, wherein the dispensing group comprises an engaging member to engage in a releasable manner a filter holder holding a filter with a coffee powder puck, wherein the hydraulic circuit comprises a first proportional two-way solenoid valve, and a second solenoid valve with at least three ways that is arranged in the hydraulic circuit downstream of the first solenoid valve, and a flow measuring device for the water in the hydraulic circuit, the flow measuring device for water cooperating with the first solenoid valve.

[0026] According to embodiments, the first solenoid valve and the second solenoid valve are independently operable to open or close one port of the first and second solenoid valves.

[0027] According to embodiments, the first solenoid valve comprises a first inlet port and a second outlet port and wherein the second solenoid valve is a solenoid valve comprising a first inlet port, a second outlet port and a third exhaust port.

[0028] According to embodiments, in a step of filling the infusion chamber, the first solenoid valve is partially open and wherein the first port and the second port of the second solenoid valve are open and in fluid communication, so that water flows from the coffee boiler to the filter at a pressure lower than a dispensing pressure, wherein the dispensing pressure is the pressure for dispensing an espresso coffee after the pre-infusion step. The pressure for dispensing an espresso coffee can be between 9 and 12 bar, for example approximately 9-10 bar.

[0029] According to embodiments, the flow measuring device for water comprises a volumetric meter, configured to detect a slowing of water flow, wherein the slowing of water flow is indicative of the filling of the infusion chamber.

[0030] According to embodiments, the volumetric meter is arranged upstream of the coffee boiler or the volumetric meter is arranged downstream of the coffee boiler, or the volumetric meter is integrated into the first solenoid valve or the volumetric meter is arranged downstream of the first solenoid valve.

[0031] According to embodiments, the machine also comprises a control unit that is connected to the flow measuring device, the first solenoid valve and the second solenoid valve to control the first and second solenoid valves based on a signal received from the flow measuring device.

[0032] According to embodiments, the control unit is configurable to set a pre-infusion time, wherein the pre-infusion time is a function of an opening percentage of the first solenoid valve.

[0033] According to another aspect, the present invention provides a method in an espresso coffee machine, for carrying out a pre-infusion step and a subsequent extraction or dispensing step, wherein the espresso coffee machine comprises a coffee boiler configured to contain water, a dispensing group and a hydraulic circuit between the coffee boiler and the dispensing group, wherein the dispensing group comprises an engaging member to engage in releasable manner a filter holder holding a filter with a coffee powder puck, the method comprising: providing a first two-way proportional solenoid valve and a second solenoid valve with at least three ways that is arranged in the hydraulic circuit downstream of the first proportional solenoid valve; carrying out a first step of filling the infusion chamber at least in correspondence with an empty space above the coffee puck by keeping the first solenoid valve partially open and the second solenoid valve completely open; wherein the first solenoid valve is kept partially open based on a signal generated by a flow measuring device for the water in the hydraulic circuit.

[0034] According to embodiments, the first solenoid valve is kept partially open until the flow measuring device for the water in the hydraulic circuit detects a slowing of the flow.

[0035] According to embodiments, the flow measuring device for the water in the hydraulic circuit comprises a volumetric meter that is arranged upstream of the coffee boiler or is arranged downstream of the coffee boiler, or is integrated into the first solenoid valve or is arranged downstream of the first solenoid valve.

[0036] According to embodiments, the machine also comprises a control unit that is connected to the flow measuring device, to the first solenoid valve and to the second solenoid valve to control the first and second solenoid valves according to a signal received from the flow measuring device.

[0037] According to embodiments, the method also comprises the step of setting a pre-infusion time, where the pre-infusion time is a function of an opening percentage of the first solenoid valve.

[0038] According to embodiments, at the end of the pre-infusion step, an infusion step is carried out in which the first solenoid valve is substantially completely open.

[0039] BRIEF DESCRIPTION OF THE FIGURES

[0040] The present invention will become clear from the following description, given purely by way of example and not of limitation, to be read with reference to the attached figures, wherein:

[0041] - FIG. 1 is an espresso coffee machine that could incorporate the pre-infusion device of the present invention; - FIG. 2 shows a dispensing group with coffee boiler and with the pre-infusion device of the present invention;

[0042] - FIG. 3 is a sectional view of the dispensing group of FIG. 2 and

[0043] FIG. 3A is a section made at the line A-A of FIG. 3;

[0044] - FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D illustrate, in a simplified manner, some operating steps of the two solenoid valves;

[0045] - FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D illustrate, in a simplified manner, the operating steps illustrated in Figures 4A, 4B, 4C and 4D and the controlling of the two solenoid valves; and

[0046] - FIG. 6 is a section illustrating the entry of water during the pre-infusion step.

[0047] DETAILED DESCRIPTION

[0048] In FIG. 1 , an espresso coffee machine 1 that can incorporate the present invention is illustrated, for purely illustrative purposes. The machine 1 typically comprises a machine body 2 that contains all the main components. The machine body 2 is box-shaped and can comprise pucks made of metal sheets or the like. The machine 1 comprises a dispensing group GR configured to releasably engage a filter holder PF (shown in Figures 2, 3 and 6). The dispensing group, at the device for engaging the filter holder, comprises dispensing members for dispensing and, typically, uniformly distributing, hot water under pressure towards the ground coffee puck. A member for uniformly distributing the water on the coffee puck can comprise a perforated disk generally called a “shower head”.

[0049] The machine 1 can comprise controls, for example one or two knobs 3 and a lever LV or button or switch for starting and stopping the dispensing (or extraction) of the coffee.

[0050] The machine 1 can also comprise a display 4 to show select operating parameters.

[0051] The machine 1 can also comprise one or more dials 5 to show, for example, pressure or temperature values.

[0052] The machine 1 can also comprise a steam wand 6 to dispense steam, for example, for frothing milk or the like.

[0053] Under the dispensing group GR a drip tray 7 and a grid can be provided on which to place a cup while the espresso coffee is being dispensed. The filter holder PF comprises a body PF-B and a handle PF-H. The body, in turn, is configured to hold a filter FL where a puck FP of coffee powder is formed.

[0054] The filter FL is substantially cup-shaped, with a bottom provided with a plurality of holes or openings.

[0055] Machine 1 can comprise, inside, a steam boiler and a coffee boiler CB.

[0056] In FIG. 2, a dispensing group GR with a coffee boiler CB is shown, by way of example. A filter holder PF is releasably mounted on the dispensing group GR, as also shown in the section of FIG. 3 and in FIG. 6.

[0057] The pressurized water, possibly preheated, is introduced into the coffee boiler CB. It is heated to the usage temperature and is directed towards the puck FP of ground coffee CP (typically pressed) in the filter FL. In embodiments, the incoming water of the coffee boiler CB can be preheated in a preheater that uses the heat of the water provided in the steam boiler.

[0058] According to the present invention, along a hydraulic circuit HC between the coffee boiler CB and the filter FL, a first solenoid valve Evp1 and a second solenoid valve EV2 are provided, downstream of the first solenoid valve Evp1 , which operate as shown schematically in the various Figures 4A, 4B, 4C and 4D. The first solenoid valve Evp1 can be of the two-way type, with a first inlet port and a second outlet port. The first solenoid valve Evp1 is of the proportional type, capable of partializing the flow of water that passes from the first inlet port to the second outlet port.

[0059] The water entering the first solenoid valve Evp1 is typically hot water coming from the coffee boiler CB. The water exiting the first solenoid valve Evp1 is directed towards the puck FP of ground coffee in the filter holder PF. Before reaching the coffee puck in the filter holder, the water exiting the first solenoid valve EVp1 enters the second solenoid valve EV2.

[0060] As mentioned above, the first solenoid valve Evp1 is of the proportional type and is configured to partially or completely open the passage between the first inlet port and the second outlet port. For example, the passage between the first inlet port and the second outlet port can be open by 10%, 20%, ..., 80%, 90% or 100%. Of course, it can also be opened by different percentages, with a greater or lesser fineness. Typically, a proportional solenoid valve is controlled in opening (partial or total) or in closing by means of a control unit CU shown in Figures 5A, 5B, 5C and 5D.

[0061] The second solenoid valve EV2 can be of the three-way type to allow the water to be discharged at the end of the dispensing through the third port. The second solenoid valve EV2 comprises a first inlet port, a second outlet port and, as mentioned above, a third exhaust port.

[0062] FIG. 4A shows the stand-by and discharge step in which the system and the solenoid valves are at the end of a dispensing. In this step, the first solenoid valve Evp1 is closed (opening % op = 0%) and the second solenoid valve EV2 is also closed (opening % op = 0%). In this way, hot water under pressure does not flow from the coffee boiler CB towards the coffee puck. The drain of the second solenoid valve EV2 (the third port of EV2) is open, to discharge the residual water still present in the circuit and in the infusion chamber.

[0063] FIG. 4B shows the water loading step for pre-infusion. In this step, the first solenoid valve Evp1 is partially opened (the first port and the second port are partially in communication with one another). In this water loading step for preinfusion, the second solenoid valve EV2 is open and therefore the first port and the second port of the second solenoid valve EV2 are in complete communication with one another. In FIG. 4B, the first valve Evp1 is partially open (opening percentage op < 100%); the second solenoid valve EV2 is fully open and therefore the opening percentage for the second solenoid valve EV2 is op = 100%.

[0064] This step causes the coffee puck to be wetted with water, gradually filling the infusion chamber IC (FIG. 6) and the part of the circuit between the second solenoid valve and the infusion chamber IC. The pressure does not increase until the infusion chamber and the aforementioned part of the circuit are completely filled. The expression “infusion chamber” comprises the free space between the upper surface of the coffee puck and the shower head from which the water for coffee extraction comes out.

[0065] The device could typically comprise a volumetric meter FM, configured to detect a slowing of the water flow. The slowing of the water flow is considered indicative of the filling of the pre-infusion chamber. According to embodiments, the volumetric meter FM is arranged upstream of the coffee boiler CB. Alternatively, the volumetric meter FM is arranged downstream of the coffee boiler. The volumetric meter can also be integrated into the first valve Evp1 or be placed downstream of the first valve Evp1 .

[0066] FIG. 4C shows the dispensing step. During said step, the first proportional solenoid valve Evp1 is opened again (the first port and the second port are in communication with one another and the opening percentage op is substantially equal to 100%), allowing the flow of hot water under pressure to act on the coffee puck and to continue with the extraction step. Naturally, in the extraction step, the second solenoid valve EV2 remains open (opening percentage op substantially equal to 100%) as in the pre-infusion step (the first port and the second port of the second solenoid valve EV2 are in communication with one another).

[0067] FIG. 4D shows the discharge step that can advantageously be done at the end of the dispensing. In this step, the first solenoid valve Evp1 and the second solenoid valve EV2 are closed (the first port is not in communication with the second port and the opening percentage op is equal to 0%). In this way, the hot water under pressure stops flowing from the coffee boiler CB. To discharge the residual water still present in the circuit and in the infusion chamber, the drain (the third port of EV2) of the second solenoid valve EV2 is opened. Therefore, the water is discharged at the end (and not before) of the extraction. It is not discharged at the end of the pre-infusion.

[0068] Figures 5A, 5B, 5C and 5D are other representations of the steps illustrated in the corresponding Figures 4. These figures show the control unit CU which is connected to the volumetric meter FM, to the first solenoid valve Evp1 and to the second solenoid valve EV2. In particular, the control unit CU controls the opening of the solenoid valves Evp1 and EV2 in the different steps. The control unit could comprise an electronic board with a processing device (CPU).

[0069] FIG. 5A shows the stand-by and discharge step in which the system and the solenoid valves are at the end of a dispensing. In this step, the control unit CU keeps the first solenoid valve Evp1 closed and also keeps the second solenoid valve closed. Advantageously, the exhaust of the second solenoid valve EV2 is open. In FIG. 5B, dispensing begins and the valve Evp1 opens partially to a preset percentage. The flow meter FM sends the flow rate data to the control unit CU which controls the partial opening of the first solenoid valve and the full opening of the second solenoid valve. When the flow meter FM detects a slowing of the flow rate in a given period of time, it detects that the circuit has been saturated and therefore that the pre-infusion step is finished.

[0070] Subsequently, as shown in FIG. 5C, the actual infusion step begins and the first valve Evp1 is also commanded to open to 100%.

[0071] Once the infusion step and therefore the espresso coffee dispensing step in the cup is finished, the first valve Evp1 is again controlled to close. The control unit CU, in addition to closing the first solenoid valve, also controls the closing of the second solenoid valve EV2 and opens the exhaust port of the latter.

[0072] According to embodiments, the control unit CU can be programmed and / or set (in the factory or by the user) so as to carry out the pre-infusion step (FIG. 4B and FIG. 5B) at a given fixed speed or according to a plurality of speeds.

[0073] Based on the speed of execution of the pre-infusion, the control unit will set a corresponding opening percentage of the first proportional solenoid valve Evp1. For example, in a set time T1 , the opening percentage op of the solenoid valve Evp1 will be for example 10%. In a set time T2 < T1 , the opening percentage op of the solenoid valve Evp1 will be for example 20%. Obviously, by further opening the first solenoid valve, the time will be shorter than in the situation with the solenoid valve Evp1 further closed.

Claims

CLAIMS1. An espresso coffee machine (1 ) comprising a coffee boiler (CB) configured to contain water, a dispensing group (GR) and a hydraulic circuit (HC) between the coffee boiler (CB) and the dispensing group (GR), wherein the dispensing group (GR) comprises an engaging member (CM) to engage in releasable manner a filter holder (PF) holding a filter (FL) with a coffee powder puck (FP), wherein the hydraulic circuit (HC) comprises a first proportional two- way solenoid valve (Evp1 ), and a second solenoid valve (EV2) with at least three ways that is arranged in the hydraulic circuit (HC) downstream of the first solenoid valve (Evp1 ), and a device (FM) for measuring the flow of water in the hydraulic circuit, the device (FM) for measuring the flow of water cooperating with the first solenoid valve (Evp1 ).

2. The machine (1 ) of claim 1 , wherein the first solenoid valve and the second solenoid valve (Evp1 , EV2) are independently operable to open or close a port of the first and second solenoid valves.

3. The machine (1 ) of claim 1 or 2, wherein the first solenoid valve (Evp1 ) comprises a first inlet port and a second outlet port and wherein the second solenoid valve (EV2) is a solenoid valve comprising a first inlet port, a second outlet port and a third exhaust port.

4. The machine (1 ) of claim 3, wherein in a step of filling the infusion chamber(IC), the first solenoid valve (Evp1 ) is partially open and wherein the first port and the second port of the second solenoid valve (EV2) are open and in fluid communication, so that water flows from the coffee boiler (CB) to the filter (FL) at a pressure lower than a dispensing pressure, wherein the dispensing pressure is the pressure for dispensing an espresso coffee after the preinfusion step.

5. The machine of any one of the preceding claims, wherein the flow measuring device (FM) for water comprises a volumetric meter (FM), configured to detect a slowing of water flow, wherein the slowing of water flow is indicative of the filling of the infusion chamber (IC).

6. The machine (1 ) of claim 5, wherein the volumetric meter (FM) is arrangedupstream of the coffee boiler (CB) or the volumetric meter (FM) is arranged downstream of the coffee boiler (CB), or the volumetric meter is integrated into the first solenoid valve (Evp1 ) or the volumetric meter is arranged downstream of the first solenoid valve (Evp1 ).

7. The machine (1 ) of any one of the preceding claims, further comprising a control unit (CU) which is connected to the flow measuring device (FM), to the first solenoid valve (Evp1 ) and to the second solenoid valve (EV2) to control the first and second solenoid valves according to a signal received from the flow measuring device (FM).

8. The machine (1 ) of claim 7, wherein the control unit (CU) is configurable to set a pre-infusion time, wherein the pre-infusion time is a function of an opening percentage of the first solenoid valve (Evp1 ).

9. A method in an espresso coffee machine (1 ), for carrying out a pre-infusion step and a subsequent extraction or dispensing step, wherein the espresso coffee machine (1 ) comprises a coffee boiler (CB) configured to contain water, a dispensing group (GR) and a hydraulic circuit (HC) between the coffee boiler (CB) and the dispensing group (GR), wherein the dispensing group (GR) comprises an engaging member to engage in releasable manner a filter holder (PF) holding a filter (FL) with a coffee powder puck (FP), the method comprising: providing a first two-way proportional solenoid valve (Evp1 ) and a second solenoid valve (EV2) with at least three ways that is arranged in the hydraulic circuit downstream of the first proportional solenoid valve (Evp1 ); carrying out a first step of filling the infusion chamber (IC) at least in correspondence with an empty space above the coffee puck (CP) while keeping the first solenoid valve (Evp1 ) partially open and the second solenoid valve (EV2) completely open; wherein the first solenoid valve (Evp1 ) is kept partially open based on a signal generated by a flow measuring device (FM) for the water in the hydraulic circuit (HC).

10. The method of claim 9, wherein the first solenoid valve (Evp1 ) is kept partially open until the flow measuring device (FM) for the water in the hydraulic circuit(HC) detects a slowing of the flow.11 . The method of claim 9 or 10, wherein the flow measuring device (FM) for the water in the hydraulic circuit (HC) comprises a volumetric meter (FM) which is arranged upstream of the coffee boiler (CB) or is arranged downstream of the coffee boiler (CB), or is integrated into the first solenoid valve (Evp1 ) or is arranged downstream of the first solenoid valve (Evp1 ).

12. The method of claim 9, 10 or 11 , wherein the machine also comprises a control unit (CU) which is connected to the flow measuring device (FM), to the first solenoid valve (Evp1 ) and to the second solenoid valve (EV2) to control the first and second solenoid valves according to a signal received from the flow measuring device (FM).

13. The method of claim 12, further comprising the step of setting a pre-infusion time, wherein the pre-infusion time is a function of an opening percentage of the first solenoid valve (Evp1 ).

14. The method of any one of claims 9-13, wherein at the end of the pre-infusion step an infusion step is carried out in which the first solenoid valve (Evp1 ) is substantially completely open.

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