Coffee brewing device

Abstract

The invention relates to a fully automatic coffee machine (100) comprising a coffee extraction unit (10) having: - a brewing chamber (1) for receiving coffee powder, - an upper piston (2), - a lower piston (3) movable within the brewing chamber (1) between a lowermost position and an uppermost position, - wherein the lower piston (3) comprises a piston stem (31) comprising an internal channel (311) extending from a channel inlet (311a) at a side wall surface of the stem to a channel outlet (311b) at a bottom wall surface of the stem, and wherein the channel inlet (311a) is designed and positioned on the side wall surface of the stem such that it overlaps with a bottom wall (11) of the brewing chamber only when the lower piston is in the uppermost position.

Description

Technical Field

[0001] This invention relates to an apparatus for preparing coffee beverages. In particular, this invention relates to a fully automatic coffee apparatus. Background Technology

[0002] Typically, in a fully automatic coffee machine, coffee is prepared in a brewing chamber configured to receive a predetermined amount of coffee grounds. This coffee grounds are then compressed by at least one movable piston, and pressurized water is introduced to brew the compressed coffee grounds. Finally, the extracted coffee beverage flows from the outlet of the brewing chamber into a beverage cup.

[0003] Various types of brewing chambers have been developed for fully automatic coffee machines.

[0004] One type is called a "bottom-up" brewing chamber and involves a brewing chamber in which water is introduced through the bottom of the chamber and the brewed coffee beverage is discharged through the top of the brewing chamber.

[0005] This type of bottom-up brewing chamber has a drawback: the brewed coffee cannot be completely drained from the brewing chamber, and a small amount of residual liquid remains in the brewing chamber and is collected at the bottom of the chamber.

[0006] If not drained, the residual liquid will affect the quality of the next brew, as it mixes with the subsequent coffee beverage prepared in the brewing chamber. The usual method of draining this residual liquid is via a water pipe configured to introduce water into the brewing chamber and typically located at the bottom of the chamber. This pipe usually includes a three-way valve that allows the inlet of the brewing chamber to connect to a hot water supply system or a liquid drain device. This valve allows hot water to be introduced from the hot water supply system into the brewing chamber during coffee preparation, and then the residual liquid to be drained from the brewing chamber to the liquid drain device after coffee preparation. This configuration is implemented in WO2016116981, which recognizes that using this implementation can cause other problems. In practice, because the residual liquid includes coffee extract and particles, some residue settles in the pipe extending between the inlet of the brewing chamber and the three-way valve, and after a certain period, blocks the water pipe. Furthermore, these residues affect the quality of the hot water introduced into the brewing chamber and the quality of the coffee beverage.

[0007] Considering these drawbacks, the cost of a three-way valve is not worthwhile.

[0008] To remove residual liquid from a bottom-up brewing chamber, EP3545801 relates to residual water obtained by extruding brewed coffee grounds from the brewing chamber. The solution includes forming a drain outlet between a piston rod and a hole for the rod located at the bottom of the chamber.

[0009] A significant problem with this solution involves the liquid flowing beneath the piston rod and the bottom of the chamber, as well as liquid splashing through the internal parts of the machine. In fact, the existing technology does not explain how to collect residual liquid within the machine. Furthermore, it is questionable that the connection between the tapered shape of the rod and the orifice at the bottom of the chamber is configured to seal tightly when the bottom is closed. It is expected that deposits of coffee extract and fine particles will accumulate on the seals and on the edges of the orifice at the bottom chamber, and without regular cleaning requiring complete disassembly of the chamber, a leak-proof seal will no longer be guaranteed.

[0010] When brewing roasted and ground (R&G) coffee, the optimal quality of the coffee beverage is directly related to the precise temperature of the water used in the extraction process. A well-known problem is preparing the first cup of coffee, and sometimes even the second cup, after the machine has been idle for some time. Due to the thermal inertia of the brewing chamber itself and the presence of water inside the tubing, the temperature of the first cup is never the temperature required for the brewing operation, and the quality of the first cup is poor, and usually the second cup is as well.

[0011] To address this problem, various solutions have been proposed, such as dispensing one or two cups of lower-quality coffee to heat the chamber. However, such solutions cause coffee to spill and are not feasible in self-service coffee makers; an operator must be present to pour the spilled coffee into the sink.

[0012] In another solution, similar to EP1009270, a heating element is provided inside the brewing chamber itself, where an electric heating resistor is embedded within the main body of the chamber. This solution has several drawbacks. First, it requires a complex chamber structure, making the chamber difficult to maintain. Second, this solution cannot heat residual water remaining in the water supply line, meaning the first cup is never brewed at the optimal temperature. Additionally, the relatively high temperature of the chamber walls alters the viscosity of the coffee within the chamber and directly affects the quality of the brewed coffee. Finally, this electrically heated chamber consumes a lot of energy.

[0013] Another solution involves introducing hot water into the brewing chamber to heat the water line and the brewing chamber to the desired temperature, and then draining the heated water before preparing the first cup of coffee. WO2020082190 describes such a solution: based on the same fluid line supply construction as WO2016116981 above, heated hot water is discharged through the water line and a three-way valve that drains the water into a drain pipe. However, this solution still requires the use of a three-way valve, which incurs associated costs and maintenance.

[0014] The purpose of this invention is to address at least some of the shortcomings of the prior art bottom-up brewing chamber, or at least to provide an alternative to the prior art bottom-up brewing chamber.

[0015] In particular, the object of the present invention is to provide a fully automatic coffee machine including a bottom-up brewing chamber capable of discharging residual liquid.

[0016] It would be advantageous to provide a fully automatic coffee machine that includes a bottom-up brewing chamber that allows residual liquid to be discharged without contaminating the water supply line.

[0017] It would be advantageous to provide a fully automatic coffee machine that includes a bottom-up brewing chamber that can drain residual liquid without using an expensive three-way valve.

[0018] It would be advantageous to provide a fully automatic coffee machine that includes a bottom-up brewing chamber capable of preparing a first cup with the same mass as other cups.

[0019] It would be advantageous to provide a fully automatic coffee machine that includes a bottom-up brewing chamber capable of preparing a first cup of the same quality as other cups without spilling coffee or electricity. Summary of the Invention

[0020] In a first aspect of the invention, a fully automatic coffee machine is provided, comprising a coffee extraction unit, the coffee extraction unit comprising:

[0021] - A brewing chamber for receiving roasted and ground coffee powder, the chamber comprising an upper edge, a bottom wall, and a water inlet.

[0022] - Upper piston,

[0023] The upper piston is configured to move through the upper edge of the brewing chamber and further move within the brewing chamber to allow relative movement between the brewing chamber and the upper piston.

[0024] The upper piston includes a liquid outlet conduit.

[0025] - Lower piston, which is movable between the following positions within the brewing chamber:

[0026] The lowest position, where the lower piston is located on the bottom wall of the brewing chamber, and

[0027] The highest position, where the lower piston is located at the upper edge of the brewing chamber.

[0028] -The lower piston includes a piston rod that extends through the bottom wall of the brewing chamber, and

[0029] The piston rod includes an internal channel extending from a channel inlet on the side wall surface of the rod to a channel outlet on the bottom wall surface of the rod, and

[0030] The channel inlet is designed and positioned on the side wall surface of the rod, such that the channel inlet overlaps with the bottom wall of the brewing chamber only when the lower piston is in a higher position.

[0031] The coffee machine includes a brewing chamber configured to achieve bottom-up extraction. The chamber is designed and oriented along a longitudinal axis. This axis can be oriented substantially vertically, or, for example, at an angle of up to 30° to the vertical. During extraction, water is introduced through the bottom of the chamber and the extracted coffee is dispensed through the top of the chamber.

[0032] The brewing chamber defines an internal volume configured to receive a measured amount of roasted and ground coffee powder to be extracted, preferably roasted and ground coffee. Typically, the chamber is cylindrical, having sidewalls extending upwards from the bottom wall to the upper edge. The longitudinal axis of the cylindrical shape is preferably oriented substantially vertically.

[0033] The top of the brewing chamber is open to allow the coffee grounds to be extracted to be introduced.

[0034] The brewing chamber includes a water inlet configured to introduce water into the chamber to extract coffee grounds present within it. Typically, the water inlet is located inside the side wall of the chamber, preferably near the bottom wall.

[0035] A coffee machine includes two pistons that can move through the internal volume of a chamber.

[0036] The first piston is capable of moving through the upper part of the chamber and is called the upper piston.

[0037] The upper piston is designed to move through the upper edge of the brewing chamber and further within the brewing chamber to allow for relative movement between the brewing chamber and the upper piston. The upper piston is also designed to compress the coffee grounds present within the chamber.

[0038] The upper piston includes a liquid outlet conduit. This conduit is capable of dispensing the extracted beverage from the chamber, preferably coffee. Typically, the conduit extends from the piston to a nozzle for dispensing the beverage into a cup.

[0039] The second piston is called the lower piston.

[0040] The lower piston is movable between two end positions within the brewing chamber. One end position is the lowest position of the second piston within the chamber. In this lowest position, the head of the lower piston is positioned against the bottom wall of the brewing chamber. Typically, the lower piston is positioned in this lower position during the process of introducing coffee grounds into the chamber and during the process of extracting the coffee grounds with water.

[0041] The other end position is the highest position of the second piston within the chamber. At this higher position, the upper surface of the lower piston head is at the upper edge of the brewing chamber. Typically, the lower piston is positioned at this higher position during the operation of discharging the extracted coffee grounds from the chamber.

[0042] The lower piston consists of a head and a rod.

[0043] Typically, the head features water inlets configured to introduce water from the inlet upwards into the compressed coffee grounds within the chamber between the upper and lower pistons.

[0044] The lower piston is assembled into the brewing chamber such that its piston rod extends through an opening in the bottom wall of the brewing chamber, with the free end of the rod located outside the chamber. The piston rod is configured to move up and down within the opening.

[0045] The rod includes an internal channel extending from a channel inlet on a side wall surface to a channel outlet on a bottom wall surface. This channel forms a fluid passage for liquid in contact with the side surface of the rod, extending downwards to a location below the bottom end of the rod.

[0046] The inlet of the channel is designed and positioned on the side wall surface of the rod, such that the inlet overlaps with the bottom wall of the brewing chamber only when the piston is in a higher position.

[0047] Therefore, when the lower piston is at its highest position, capable of discharging the extracted coffee, the channel inlet forms an opening at the bottom of the chamber to drain any residual liquid collected there. At this highest position, the lower piston can simultaneously discharge the coffee cake and any remaining liquid.

[0048] The residual liquid is not drained through the inlet, nor is it retained in part of the water supply pipe or at the bottom of the chamber, thus extracting the next coffee beverage prepared in the brewing chamber with optimal quality.

[0049] Typically, coffee machines include a waste liquid collector, and a channel outlet on the bottom wall surface of the lever is connected to the waste liquid collector, for example, a drip tray.

[0050] Therefore, the residual liquid flows directly to the waste liquid collector through a dedicated pipe connection and will not flow and contaminate other pipes or parts of the machine, such as the contact surfaces of the rod and the opening at the bottom of the chamber or the outer surface of the lower piston rod.

[0051] The machine includes a support frame on which the brewing chamber is mounted.

[0052] The relative movement of the brewing chamber and the two pistons can be achieved indistinguishably in the following ways:

[0053] - Keep the brewing chamber fixed to the support frame, and actuate the piston inside and / or outside the chamber.

[0054] and / or

[0055] - The brewing chambers are actuated relative to the support frame, while the pistons remain fixed or are passively driven by the movement of the chambers that hold them.

[0056] In a preferred embodiment, the brewing chamber can be moved by a drive component. The drive component can be a rack or any other known component.

[0057] In this embodiment, preferably:

[0058] - The upper piston is fixed.

[0059] The lower piston rod includes a free bottom end located outside the brewing chamber and movable together with the piston and the chamber.

[0060] - The device includes a fixed bottom stop wall that can contact the bottom end of the lower piston rod.

[0061] - The movement of the lower piston depends on the movement of the brewing chamber and / or the contact between the free bottom end and the lower stop wall or the contact between the lower piston and the upper piston.

[0062] Preferably, in this preferred embodiment, the lower piston has no guide member, retaining member, and spring, which means that the lower piston is passive and there is no active member to change the position of the lower piston relative to the brewing chamber.

[0063] Preferably, in this preferred embodiment, the rod and / or lower piston are provided with friction components to control the movement of the rod and / or lower piston relative to the inner wall of the brewing chamber. These components allow the lower piston to be held in one position relative to the brewing chamber.

[0064] Preferably, in this preferred embodiment, the fixed bottom stop wall includes a channel configured to connect the channel outlet of the internal channel of the rod to a drain pipe. The drain pipe may be configured to guide liquid water to a drip tray or any drainage component of the device.

[0065] In an alternative implementation, the brewing chamber can be fixedly installed in the machine, and the upper and lower pistons can be moved inside and outside the brewing chamber by a drive component.

[0066] Typically, a coffee extraction unit includes a dispensing device for extracting coffee grounds (coffee cake). This dispensing device is designed to sweep across the area above the upper edge of the chamber by any rotational or translational movement when the piston is at its highest position.

[0067] Typically, fully automatic coffee machines include a pressurized hot water system, which at least includes a water supply system, a water heater, and a water pump. This system is connected to the water inlet of the brewing chamber.

[0068] Therefore, hot pressurized water is supplied to the brewing chamber to extract roasted and ground coffee powder.

[0069] Typically, fully automatic coffee machines include a control system that is configured as follows:

[0070] -Actuates the movement of the brewing chamber and / or piston,

[0071] - A device for controlling a pressurized hot water fluid system.

[0072] In a second aspect, a method is provided for preparing coffee beverages using a fully automatic coffee device such as those described above, wherein the method includes the following steps:

[0073] a- In the ingredient dispensing position, the lower piston is in its lowest position, and the upper piston is positioned at a certain distance from the upper edge of the chamber. Outside the chamber, a certain amount of roasted and ground coffee powder is supplied to the brewing chamber. Then,

[0074] b - This causes the chamber and the upper piston to move relative to each other to compress a specific amount of coffee grounds, then,

[0075] c- Hot water is introduced into the brewing chamber through the inlet, extracting coffee grounds and dispensing the extracted coffee beverage through the beverage outlet of the upper piston.

[0076] d - Move the chamber, upper piston, and lower piston relative to each other so that:

[0077] Position the upper edge of the chamber away from the upper piston, and

[0078] Position the lower piston at the upper edge of the brewing chamber, and

[0079] The extracted coffee grounds are discharged from the lower piston, and

[0080] The residual liquid present at the bottom of the chamber is distributed through the internal channel of the lower piston rod.

[0081] This method allows for the removal of any liquid still present in the brewing chamber and collected at the bottom at the end of coffee preparation. The liquid removal occurs during the removal of the coffee puck, meaning there is no additional time spent on the entire coffee preparation process compared to existing technologies. The removal step remains invisible compared to the usual sequence.

[0082] At the start of step a), there is no coffee in the brewing chamber.

[0083] Preferably, the method includes at least one additional step e) after step d), which includes moving the chamber, the upper piston, and the lower piston relative to each other in a closed position, wherein the lower piston is in the lowest position and the upper piston closes the chamber.

[0084] This enclosed configuration prevents the chamber temperature from dropping too quickly after coffee preparation in step c). Due to the chamber's enclosed design, the chamber walls remain warm, and if new coffee is prepared, the chamber temperature is immediately suitable for optimal preparation.

[0085] Preferably, the chamber remains in the closed position until a new coffee beverage is ordered, and when a new coffee beverage is ordered, the chamber moves to the dispensing position to achieve step a).

[0086] In a preferred embodiment, the method includes at least one additional step a0) prior to implementing step a), which includes:

[0087] a0) Move the chamber, upper piston, and lower piston relative to each other so that:

[0088] Position the upper edge of the chamber away from the upper piston, and

[0089] Position the lower piston at the upper edge of the brewing chamber, and

[0090] Hot water is introduced through the inlet to purify the hot water fluid pipeline and distributed through the internal channels of the lower piston.

[0091] During step a0), which is performed before steps a) to e) of coffee preparation, the brewing chamber is positioned such that water can be simultaneously introduced from the inlet and immediately discharged from the chamber through the internal channel of the lower piston rod. As a result, if no coffee is extracted within a certain time and the temperature of the water stagnating in the pipe upstream of the inlet has decreased, the water can be purified and discharged before coffee preparation. Then, the next batch of coffee prepared through steps a) to e) is extracted using hot water at the correct expected temperature, instead of a portion of cold water.

[0092] The volume of hot water introduced into the brewing chamber depends on the dead volume of the fluid in a specific water flow line, which is the volume of water stagnating between the outlet of the water heating device and the inlet of the brewing chamber, and also depends on the dead volume of the fluid in the bottom portion of the chamber.

[0093] In another preferred embodiment, the method may include additional steps prior to step a), these steps including:

[0094] a1 - This causes the brewing chamber, upper piston, and lower piston to move relative to each other so that:

[0095] Use a piston to seal the chamber, and

[0096] Position the lower piston within the brewing chamber, ensuring the inlet of the internal channel is located below the bottom wall of the chamber.

[0097] Hot water is introduced through the inlet to fill at least a portion of the internal volume of the brewing chamber defined between the upper and lower pistons, and then...

[0098] a2 - Move the chamber, upper piston, and lower piston relative to each other to position the lower piston at the upper edge of the brewing chamber, so as to distribute the volume of hot water through the internal channel of the lower piston, then,

[0099] a3 - moves the chamber, upper piston, and lower piston relative to each other to the dispensing position.

[0100] These steps allow hot water to be introduced into the brewing chamber when there is no coffee to preheat it. Specifically, these steps can be implemented when no coffee beverage has been prepared in the brewing chamber for a certain period, resulting in cold water in the brewing chamber and supply lines. Any first and even second cup of coffee prepared under these cold conditions will not have the desired quality. This specific time between two preparations can vary depending on the materials used to manufacture the equipment and / or on the machine's external environment (in a coffee shop, outside, and also depending on geographical location (cold or hot climate)).

[0101] In step a1), hot water is introduced into the brewing chamber. The volume of hot water can depend on the material used to manufacture the brewing chamber. This volume can be selected by the operator in the coffee machine's settings menu, taking into account the machine's environment or water conservation considerations. Preferably, the internal volume of the brewing chamber, defined between the upper and lower pistons, is smaller than the maximum internal volume of the chamber, so that the amount of hot water introduced for heating is not too critical. This volume can be determined on a case-by-case basis, but must be sufficient to heat the chamber to a temperature similar to that obtained when just using the chamber to prepare a coffee beverage.

[0102] Once hot water is introduced, it can remain in the brewing chamber for a certain period of time to effectively heat the chamber, and this time precedes step a2). This time can be selected by the operator in the coffee machine's settings menu, taking into account the machine's environment, or to shorten the preparation time.

[0103] In step a2), heated water is discharged from the brewing chamber, and preferably hot water is introduced into the brewing chamber and discharged immediately to purify the hot water line from stagnant water.

[0104] In a preferred embodiment, step a0) is performed before step a1) to ensure optimal preheating of the brewing chamber.

[0105] In this application, the terms "inner," "top," "bottom," and "lateral" are used to describe the positional relationship of the features of the invention. These terms should be understood to mean, when positioned within a fully automated coffee-making device for beverage production, the device in its usual orientation, as shown in the figures, particularly as... Figure 6 As shown.

[0106] The foregoing aspects of the invention can be combined in any suitable manner. Furthermore, various features herein can be combined with one or more of the foregoing aspects to provide combinations other than those specifically shown and described. Further objects and advantageous features of the invention will become apparent from the claims, detailed descriptions, and accompanying drawings. Attached Figure Description

[0107] Specific embodiments of the present invention will now be further described by way of example with reference to the following accompanying drawings.

[0108] - Figure 1 A illustrates a hot water fluid system for a coffee extraction unit according to the prior art.

[0109] - Figure 2 and Figure 3 The coffee extraction unit of the fully automatic coffee machine according to the invention is shown in two different operating steps.

[0110] - Figure 4A and Figure 4B This is a view and cross-section of the lower piston according to the present invention.

[0111] - Figure 5 The steps for preparing a coffee beverage using the coffee extraction unit described above are shown.

[0112] - Figure 6 A hot water fluid system with a coffee extraction unit according to the present invention is shown.

[0113] - Figure 7 and Figure 8This demonstrates what can be done when no coffee beverage is prepared within a certain period of time. Figure 5 The steps implemented before the steps. Detailed Implementation

[0114] Figure 1 A hot water supply line for a coffee extraction unit 10 according to prior art WO2016116981 is shown. The coffee extraction section corresponds to a bottom-up configuration, wherein water is introduced at the bottom of the brewing chamber 1 and dispensed as coffee beverage at the top via line 21. This line sequentially includes at least:

[0115] -Hot water tank 101,

[0116] - Pump 102,

[0117] -Flow meter 103,

[0118] - The final hot water fluid line 7 is connected to the inlet of the brewing chamber section of the coffee extraction unit 10.

[0119] The water pipe is never completely drained due to bends in the machine, and is one of the identified reasons why excessively cold water enters the brewing unit. It is estimated that this section of the pipe contains approximately 2 ml of water.

[0120] To drain the residual liquid remaining at the bottom of the brewing chamber 1 after coffee extraction, a three-way valve 106 is provided in the hot water supply line, which allows the residual liquid to be discharged downward through the final hot water fluid line 7 to the three-way valve 106 and then to the drain pipe 8.

[0121] As mentioned in the "Background of the Invention" section above, such discharge through the final hot water fluid line 7 has serious drawbacks.

[0122] Figure 2 and Figure 3 The coffee extraction unit 10 of the fully automatic coffee machine according to the present invention is schematically shown in two different operating steps.

[0123] exist Figure 2 In the context of coffee extraction or chamber preheating, the coffee extraction unit 10 is referred to as such. Figure 3 In the text, the coffee extraction unit 10 is represented in the step of discharging the coffee cake at the end of the operation sequence for preparing a coffee beverage.

[0124] These coffee extraction units 10 include a brewing chamber 1 for receiving a measured amount of coffee powder (typically roasted and ground coffee). Preferably, the brewing chamber 1 is a cylinder with an open top, extending from a bottom wall 11 to an upper edge along a substantially vertical axis XX'. The chamber 1 includes a water inlet 13 to which a hot water fluid line is connected. The water inlet 13 is preferably positioned near the bottom of the chamber, such as in... Figure 2 The lower interior of the sidewall shown, or optionally in the bottom wall.

[0125] The coffee extraction unit 10 includes a drive component 6 for vertically moving the chamber 1 up and down. For example, the chamber 1 can be mounted on a worm gear drive via a motor component. The rotation of the worm gear causes vertical translation of the chamber.

[0126] The coffee extraction unit 10 includes an upper piston 2. This upper piston 2 has a lower end portion that is cylindrical in shape and has a diameter substantially equal to the diameter of the chamber, allowing the upper piston to pass through the upper edge 12 of the chamber and move further upward along the direction of the upper piston within the brewing chamber. Therefore, the upper piston enables coffee extraction (… Figure 2 During the process, the brewing chamber is sealed and a certain amount of roasted and ground coffee powder is introduced into the brewing chamber.

[0127] Coffee powder can be introduced into the chamber through a chute (not shown) that guides the dose of coffee powder in the direction of the top of the chamber opening.

[0128] Additionally, the upper piston 2 includes a liquid outlet conduit 21 extending from the bottom surface of the upper piston and connected to the coffee beverage dispensing line.

[0129] Coffee extraction unit 10 includes a lower piston with a head 32, the lower piston including a water outlet 34 configured to dispense water introduced through a water inlet 11 into the bottom surface of compressed coffee positioned above the head of the lower piston. Figure 2 The head functions as a water dispenser. A water dispenser (not shown) is positioned above to dispense water through the coffee grounds.

[0130] This type of piston, which draws water from the bottom up, creates a large dead volume at the bottom of the chamber and prevents all water from being expelled. It has been observed that up to 3 ml of water remains trapped at the bottom of the brewing chamber.

[0131] The head is disc-shaped and has a diameter substantially equal to the inner diameter of the cylindrical chamber. The lower piston 3 includes a rod 31 fixed to the bottom of the disc-shaped head 32 and extending downward. The piston 3 is assembled onto the chamber, wherein the rod 31 extends through an opening in the bottom wall of the chamber.

[0132] The lower piston rod 31 has no guide component or retaining spring, wherein the lower piston is coaxial with and moves within the brewing chamber.

[0133] Typically, a screen filter (not shown) is placed on the upper surface of the head of the lower piston to retain coffee particles.

[0134] The lower piston 3 can move between two end positions within the brewing chamber 1:

[0135] -Lowest position, where the lower piston is located on the bottom wall 11 of the brewing chamber ( Figure 2 ),

[0136] and

[0137] - Higher position, where the lower piston is located at the upper edge 12 of the brewing chamber ( Figure 3 ).

[0138] Coffee extraction unit 10 includes: a discharge device 4 for cleaning the extracted coffee cake ( Figure 3 The coffee extraction unit is positioned slightly above the upper edge of the brewing chamber. The cleaned coffee puck is stored in the puck receiving section.

[0139] In the embodiment shown, the upper piston 2 is fixed. The lower piston 3 is capable of coaxial movement.

[0140] - Together with brewing chamber 1, this means that when brewing chamber 1 moves, the brewing chamber simultaneously carries the lower piston, and

[0141] - Within the brewing chamber 1, this means the lower piston can move at different positions within the brewing chamber. When the brewing chamber moves upward, the movement of the lower piston 3 within the brewing chamber is driven by the contact of the disc-shaped member 32 of the piston rod against the upper piston 2, and when the brewing chamber moves downward, this movement is driven by the contact of the bottom end 312 of the lower piston rod against the bottom stop wall 5. When the lower piston 3 is stopped by the upper piston 2 during its upward movement, the continuous upward movement of the chamber allows the piston 3 to move relative to the upper piston 2 within the chamber; this also occurs during the downward movement of the chamber, along with the bottom stop wall.

[0142] The rod 31 of the lower piston 3 includes an internal channel 311 extending from a channel inlet 311a on the side wall surface of the rod to a channel outlet 311b on the bottom wall surface of the rod. This channel provides fluid communication from the channel inlet 311a downward to the channel outlet 311b.

[0143] The channel inlet 311a is designed and positioned on the side wall surface of the rod in terms of size and shape, so that the piston 3 is currently in its higher position. Figure 3When the piston rod engages in the brewing chamber, the channel inlet 311a passes through and faces the edge of the hole in the brewing chamber, thus forming a liquid outlet. Therefore, in this higher position, any waste liquid present in the chamber can flow through the channel inlet 311a and down the channel 311 to the channel outlet 311b. The waste liquid is not discharged through the inlet 11, but through the piston rod, eliminating the problem of water supply contamination.

[0144] The bottom stop wall 5 includes a channel 51 that engages with a channel outlet 311b of a rod connected to the pipe to guide waste liquid to a waste liquid collector, such as a drip tray.

[0145] The channel inlet 311a is designed and positioned on the side wall surface of the rod in terms of size and shape, such that when the piston 3 is in other operating positions (e.g., coffee preparation, brewing, preheating), the channel inlet 311a is positioned below the bottom wall 11 of the brewing chamber. Therefore, in other positions (e.g., Figure 2 (As shown in the image), no liquid can be blown through the channel inlet 311a.

[0146] Figure 4A This is a perspective view of the lower piston 3. The disc-shaped head 32 includes multiple outlets 34 to dispense water through the surface of the compressed coffee placed thereon. Typically, a circular seal is positioned in a circumferential recess 33 to provide a seal during extraction.

[0147] Figure 4B The vertical cross-section of the piston rod is shown: clearly, rod 311 is empty, providing a channel 311 for waste liquid.

[0148] Figure 5 Different steps of the method for preparing coffee beverages using a fully automated coffee equipment including a coffee extraction unit, as described above, are shown.

[0149] Step a) corresponds to the ingredient dispensing operation, wherein the chamber is in position O), with the lower piston 3 at its lowest position inside the brewing chamber and the upper piston 2 at a certain distance from the upper edge 12 of the chamber. In this position, a certain amount of roasted and ground coffee powder can be introduced through the top of the brewing chamber.

[0150] In step b), the brewing chamber 1 and the upper piston 2 move relative to each other to compress the dose of coffee powder.

[0151] In step c), hot water is introduced into the brewing chamber through inlet 71, and the hot water is dispensed by the head of the lower piston through the compressed coffee powder. The coffee powder is extracted, and the extracted coffee beverage 91 is dispensed through the beverage outlet in the upper piston.

[0152] Then, in step d), the brewing chamber 1 moves downward, which has the effect of withdrawing the upper piston 2 from the chamber. During the downward movement of the chamber, the bottom end of the lower piston rod is stopped by the stop wall, resulting in the lower piston 3 moving upward within the chamber to the upper edge of the chamber. As shown, when the lower piston 3 is in its upper position within the chamber, the coffee cake 92 is positioned above the upper edge of the chamber and can be cleaned. Simultaneously, the inlet 311a of the internal channel of the rod 31 forms an outlet for the waste liquid 72 present in the chamber. This liquid 72 is discharged through the rod and flows out from the outlet 311b.

[0153] In the final step e), chamber 1, upper piston 2, and lower piston 3 move relative to each other to close the chamber, thereby keeping the chamber temperature warm for the next preparation of coffee beverage.

[0154] Figure 6 A hot water fluid system having a coffee extraction unit 10 according to the present invention is schematically shown. The pipeline includes at least the following components in sequence:

[0155] -Cold water tank 101,

[0156] -Flow meter 103,

[0157] - Pump 102,

[0158] -Heater 104,

[0159] -Valve 105,

[0160] - The final hot water fluid line 7 is connected to the inlet of the brewing chamber section of the coffee extraction unit 10.

[0161] After coffee extraction, the waste liquid remaining at the bottom of brewing chamber 1 is discharged directly to the waste liquid collector through the rod of the lower piston. The inlet of the discharge channel formed in the rod of the lower piston acts as a passive valve, which automatically opens when the lower piston is in its higher position inside the brewing chamber. All water in the dead volume can be discharged toward the waste liquid collector (e.g., drip tray).

[0162] This passive valve enables an improved preparation process for the first coffee beverage after a long period of no preparation, during which the brewing chamber and the water held in the supply line are cold.

[0163] Specifically, when no coffee is prepared for a certain period of time, certain additional steps can be performed on the first freshly prepared coffee. This specific time may be, for example, 15 minutes, but the operator can define this period in the machine's settings menu, as the machine may vary in its environment (hot or cold) and construction.

[0164] Figure 7An additional step a0 is shown, which can be performed before preparing new coffee to raise the temperature of the supplied water in the event that no coffee is prepared for a certain period of time.

[0165] Starting from the ingredient position O shown, where the lower piston 2 is at its lowest position inside the brewing chamber and the upper piston 3 is a certain distance from the upper edge 12 of the chamber, the chamber 1, the upper piston 2, and the lower piston 3 move relative to each other so that:

[0166] - Position the upper edge 12 of the chamber away from the upper piston 2, and

[0167] Position the lower piston 3 at the upper edge 12 of the brewing chamber.

[0168] Then, hot water 71 is introduced through inlet 1 to purify the hot water fluid line 7. Since the inlet 311a of the internal channel of rod 31 forms an outlet for the liquid present in the chamber, the introduced water 71 is immediately discharged through the rod and flows out from outlet 311b. As a result, cold water retained in the water supply line is removed before a new coffee beverage is prepared.

[0169] Then, as Figure 5 As shown in the steps, coffee preparation can begin after the different components of the brewing chamber are positioned at the ingredient locations.

[0170] When no beverage is prepared within a certain period of time, the coffee machine's control unit can be configured to automatically move the brewing unit 1 to... Figure 7 The position shown in step a0) is so that cold water is ready to be purified from the water supply line 7 when coffee is ordered.

[0171] Figure 8 Other additional steps are shown that can be performed before preparing new coffee to raise the temperature of the supplied water in the event that no coffee is prepared for a period of time. These steps can be performed after step a0) or independently; this depends on the location of the coffee machine and, in particular, on external environmental conditions.

[0172] Starting from the ingredient dispensing position O), where the lower piston 3 is at its lowest position inside the brewing chamber and the upper piston 2 is a certain distance from the upper edge 12 of the chamber, in step a1), the chamber 1, the upper piston 2, and the lower piston 3 move relative to each other so that:

[0173] - Use piston 2 to seal chamber 1, and

[0174] - The lower piston 3 is positioned within the brewing chamber 1 such that the inlet 311a of the internal channel is positioned below the bottom wall 11 of the brewing chamber. In these positions of the different elements of unit 10, the brewing chamber is closed and no liquid can be discharged from the bottom.

[0175] Then, hot water is introduced through inlet 13 into the internal volume of the brewing chamber defined by the upper piston and the lower piston, so as to fill at least a portion of the internal volume of the brewing chamber defined between the upper piston 2 and the lower piston 3.

[0176] Then, hot water 71 is held in the brewing chamber, effectively preheating it. A small volume of hot water at a temperature between 80°C and 95°C can be held in the chamber for a sufficient period of time to preheat it, as if the coffee were recently prepared. For example, 25 ml of water at 80°C to 95°C held in a 45 mm diameter plastic espresso chamber for 15 seconds is sufficient to preheat the chamber for preparing the first cup of coffee.

[0177] Following this pause, in step a2), chamber 1, upper piston 2, and lower piston 3 are moved relative to each other to position lower piston 3 at the upper edge 12 of the brewing chamber, so that hot water of that volume can be dispensed through the internal channel 311 of the lower piston. Then, in this position, hot water is introduced through inlet 13 to purify the hot water fluid line 7, and the hot water is immediately discharged through the internal channel 311 of the lower piston.

[0178] Then, in step a3), before coffee preparation begins, chamber 1, upper piston 2, and lower piston 3 are moved relative to each other to the dispensing position O, as shown below. Figure 5 As shown.

[0179] The use of hot water to heat the chamber and to purify the hot water supply lines from stagnant water significantly improves the preparation of the first cup of coffee after the machine has cooled down and no coffee has been dispensed for a certain period of time.

[0180] The preparation time of the first coffee in the sequence with a preheating chamber is increased by less than 20 seconds. The first coffee exhibits the same sensory characteristics as the following coffee prepared in a greenhouse.

[0181] The advantage of this invention is that it allows for the upgrading of existing machines by simply replacing the lower piston of the chamber with a new piston and adapting the software of the machine's control unit to command the movement of the brewing chamber and the distribution of water. This upgrade does not increase machine costs and can be easily implemented.

[0182] Another advantage is that the new fully automatic coffee machine can be manufactured using a simple one-way valve instead of the three-way valve in the hot water supply line, which reduces production costs. Furthermore, this invention prevents residual water from flowing back into the one-way valve, which could potentially cause blockage or poor sealing after a certain period.

[0183] Another advantage is that removing waste liquid from the chamber via the piston rod does not result in the discharge of the splash volume of coffee beverage in the prepared cup, as observed during the opening of a three-way valve according to the prior art (due to pressure drop). The coffee consumer does not perceive the drainage of the chamber.

[0184] Although the invention has been described with reference to the embodiments shown above, it should be understood that the invention protected by the claims is not limited in any way to the embodiments shown.

[0185] Various changes and modifications may be made without departing from the scope of the invention as defined in the claims. Furthermore, if known equivalents exist for a particular feature, such equivalents should be incorporated as expressly mentioned in this specification.

[0186] As used in this specification, the words “including,” “contains,” and similar terms should not be construed as having an exclusive or exhaustive meaning. In other words, these terms are intended to mean “including but not limited to.”

[0187] Index list in the attached figure :

[0188] Coffee extraction unit 10 Brewing chamber 1 Bottom wall 11 Upper edge 12 Inlet 13 Upper piston 2 Outlet conduit 21 Lower piston 3 Piston rod 31 Internal channel 311 Inlet 311a Outlet 311b Head 32 Friction component 33 Outlet 34 Discharge device 4 Bottom stop wall 5 Channel 51 Drive component 6 Hot water fluid line 7 Water 71 Residual liquid 72 Liquid collector 8 Roasted and ground coffee 9 Coffee beverage 91 Coffee cake 92 Coffee machine 100 Water tank 101 Pump 102 Flow meter 103 Heater 104 Valve 105 Three-way valve 106

Claims

1. A fully automatic coffee machine (100) comprising a coffee extraction unit (10) comprising: - a brewing chamber (1) for receiving roasted and ground coffee powder, the brewing chamber comprising an upper edge (12), a bottom wall (11) and a water inlet (13), - an upper piston (2), . the upper piston being configured to be movable through the upper edge of the brewing chamber and to be further moved within the brewing chamber to relatively move the brewing chamber and the upper piston, and . the upper piston comprising a liquid outlet conduit (21), - a lower piston (3) movable within the brewing chamber (1) between: . a lowermost position, wherein the lower piston is located on the bottom wall (11) of the brewing chamber, and . an uppermost position, wherein the lower piston is located at the upper edge (12) of the brewing chamber, - wherein the lower piston (3) comprises a piston rod (31) extending through the bottom wall (11) of the brewing chamber, and wherein the piston rod (31) comprises an internal channel (311) extending from a channel inlet (311a) at a lateral wall surface of the piston rod to a channel outlet (311b) at a bottom wall surface of the piston rod, and wherein the channel inlet (311a) is designed and positioned on the lateral wall surface of the piston rod such that it overlaps the bottom wall (11) of the brewing chamber only when the lower piston is in the upper position.

2. The fully automatic coffee machine according to claim 1, wherein, The fully automatic coffee machine comprises a waste liquid collector (8) and the channel outlet (311b) at the bottom wall surface of the piston rod is connected to the waste liquid collector.

3. The fully automatic coffee machine according to claim 1 or 2, wherein, The brewing chamber (1) is movable by a drive member (6).

4. The fully automatic coffee machine according to claim 1 or 2, wherein: - the upper piston (2) is fixed, - the piston rod (31) of the lower piston comprises a free bottom end (312) located outside the brewing chamber (1) and movable with the piston and the brewing chamber, - the fully automatic coffee machine comprises a fixed bottom stop wall (5) configured to contact the bottom end of the piston rod of the lower piston, - the movement of the lower piston (3) depends on the movement of the brewing chamber and / or the contact of the free bottom end (312) with the bottom stop wall (5) or the contact of the lower piston (3) with the upper piston (2).

5. The fully automatic coffee machine according to claim 1 or 2, wherein, The piston rod (31) and / or the lower piston (3) are provided with friction members to control the movement of the piston rod and / or the lower piston relative to the inner walls of the brewing chamber.

6. The fully automatic coffee machine according to claim 4, wherein, The fixed bottom stop wall (5) comprises a channel (51) configured to connect the channel outlet (311b) of the internal channel of the piston rod with a drain pipe.

7. The fully automatic coffee machine according to claim 1, wherein, The brewing chamber (1) is fixed and the upper and lower pistons (2, 3) are movable inside and outside the brewing chamber by a drive member.

8. The fully automatic coffee machine according to claim 1 or 2, wherein, The fully automatic coffee machine comprises a discharge device (4) for waste coffee.

9. The fully automatic coffee machine according to claim 1 or 2, wherein, The fully automatic coffee machine comprises a pressurized hot water fluid system comprising at least a water supply system, a water heating device and a water pump, wherein the pressurized hot water fluid system is connected to the water inlet (13) of the brewing chamber.

10. A method for preparing a coffee beverage using the fully automatic coffee machine according to any one of claims 1 to 9, wherein, The method comprises the following steps: a - in a dosing position, in which the lower piston (3) is in the lowest position inside the brewing chamber and the upper piston (2) is at a distance from the upper edge (12) of the brewing chamber and outside the brewing chamber, a dose of roasted and ground coffee powder is supplied into the brewing chamber, then, b - the brewing chamber (1) and the upper piston (2) are moved relative to each other to compress the dose of coffee powder, then, c - hot water is introduced through the water inlet (13), the coffee powder is extracted and the extracted coffee beverage is dispensed through the beverage outlet of the upper piston, then, d - the brewing chamber (1), the upper piston (2) and the lower piston (3) are moved relative to each other in order to: . position the upper edge (12) of the brewing chamber away from the upper piston (2), and . position the lower piston (3) at the upper edge (12) of the brewing chamber, and . expel the extracted coffee powder from the lower piston, and . dispense the residual liquid present at the bottom of the brewing chamber through the internal passage (311) of the piston rod of the lower piston.

11. The method of claim 10, wherein, The method comprises at least one additional step e) after step d), said step e) comprising a step of moving the brewing chamber (1), the upper piston (3) and the lower piston (2) relative to each other in a closed position, in which the lower piston is in the lowest position and the upper piston closes the brewing chamber.

12. The method of claim 10 or 11, wherein, The method comprises at least one additional step before implementing step a), said steps comprising: a0 - moving the brewing chamber (1), the upper piston (2) and the lower piston (3) relative to each other, in order to: . position the upper edge (12) of the brewing chamber away from the upper piston (2), and . position the lower piston (3) at the upper edge (12) of the brewing chamber, and . introduce hot water through the water inlet (13) in order to purge the hot water fluid line (7) and dispense said hot water through the internal passage (311) of the lower piston.

13. The method of claim 10 or 11, wherein, The method comprises additional steps before implementing step a), these steps comprising: a1 - moving the brewing chamber (1), the upper piston (2) and the lower piston (3) relative to each other, in order to: . close the brewing chamber (1) with the upper piston (2), and . position the lower piston (3) inside the brewing chamber (1) so that the passage inlet (311a) of the internal passage is positioned below the bottom wall (11) of the brewing chamber, and . introduce hot water through the water inlet (13) in order to fill at least part of the internal volume of the brewing chamber defined between the upper piston (2) and the lower piston (3), then a2 - moving the brewing chamber (1), the upper piston (2) and the lower piston (3) relative to each other in order to position the lower piston (3) at the upper edge (12) of the brewing chamber in order to dispense the volume of hot water through the internal passage (311) of the lower piston, then, a3 - moving the brewing chamber (1), the upper piston (2) and the lower piston (3) relative to each other to the dosing position.

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