METHOD FOR OPERATING A BEVERAGE PREPARATION APPLIANCE WITH A HYDRAULIC PRE-COMPACTION UNIT FOR COMPACTING A BEVERAGE SUBSTANCE

Description

[0001] The present invention relates to a method according to the preamble of claim 1.

[0002] Various designs of beverage preparation devices, particularly coffee machines, are known in the prior art. These are generally divided into different categories, such as capsule machines, fully automatic machines, portafilter machines, and the like. However, hybrid concepts or combination approaches are also known that, for example, combine aspects of a fully automatic machine and aspects of a portafilter machine.

[0003] For many devices that use a beverage substrate, for example coffee bean flour, a preparation process for carrying out the beverage production process or for carrying out a beverage dispensing includes the pre-compaction of beverage substrate, in particular coffee bean flour.

[0004] Pre-compacting the beverage substrate aims to achieve a consistently high-quality beverage during the subsequent brewing or extraction process. Therefore, the goal is to achieve a consistent level of pre-compaction, regardless of the quantity of beverage substrate or coffee bean flour used.

[0005] Pre-compaction is also known as tamping. The degree of automation in beverage preparation equipment varies depending on the type and design. However, approaches are already known from various concepts within the aforementioned categories of beverage preparation equipment where tamping or pre-compaction of the beverage substrate is performed automatically or automatically, also to improve the reproducibility of the result. For example, fully automatic machines with a toggle-lever brewing unit perform pre-compaction by mechanically adjusting a movable brewing head into / against a brewing chamber into which the beverage substrate has been filled.

[0006] In addition to mechanical systems for pre-compacting the beverage substrate, hydraulic devices and methods are also known for automating or reproducibly performing the tamping or pre-compacting process. One such approach is known, for example, from utility model DE 92 14 283 U1. Patent application DE 10 2021 123 545 A1 of the applicant also teaches various approaches to beverage preparation devices and corresponding methods in which a beverage substrate arranged in a brewing chamber or in a portafilter can be tamped by means of a hydraulic system.It is already known from the prior art to use brewing fluid for hydraulic pre-compression and to connect a hydraulic cylinder used for pre-compression to the brewing chamber or a brewing head in such a fluid-technical manner, in particular in a fluid-conducting manner, in particular to delimit it via a switchable valve, such that when a predetermined internal pressure is reached in the hydraulic cylinder and thus when a corresponding limit pressure is reached at the valve, the valve is opened and the brewing fluid can flow out of or via the hydraulic cylinder into the brewing chamber for pre-compression or be transferred into the brewing chamber.

[0007] This ensures a reproducible contact pressure during the pre-compaction of the beverage substrate in a simple and effective manner.

[0008] US Patent 2014 / 0150663 A1 discloses an espresso machine with a hydraulically driven tamper device, wherein the height of the pressed beverage substrate pellet is calculated from the volume of the hydraulic fluid measured by a flow meter. The actual height of the beverage substrate pellet calculated in this way is compared by a control unit with a desired height and used to adjust the brewing process in subsequent brewing cycles.

[0009] However, with known beverage preparation devices and operating methods that involve hydraulic pre-compression of the beverage substrate, a disadvantage is that the entire beverage supply process, particularly from activation by a user to the completion of dispensing the finished beverage, can sometimes take a relatively long time. Furthermore, there is a need to provide the produced beverages with reproducible properties or quality over the longest possible period, while simultaneously offering different beverage types, such as espresso, caffè lungo, etc., where the amount of beverage substrate can also be deliberately varied, for example, according to user preferences.

[0010] Against this background, the object of the present invention is to propose a method for operating a beverage preparation device, in particular a coffee machine, with a hydraulic pre-compression unit for compressing a beverage substrate, in which the disadvantages of the prior art are overcome, and in particular a faster dispensing of the finished beverage and / or a stabilization of the properties of the beverages over a longer period of use is improved.

[0011] This problem is solved by a method having the features of claim 1.

[0012] Advantageous embodiments of the method are the subject of the following description, the figure description, the figures and the dependent claims.

[0013] Features subsequently disclosed procedurally shall, in principle, also be deemed to be disclosed and claimable in accordance with the device.

[0014] The method for operating a beverage preparation device, in particular a coffee machine, with a hydraulic pre-compression unit for compressing a beverage substrate, preferably ground coffee beans, prior to a brewing or extraction process with a brewing fluid, preferably water, in which, during a pre-compression process, a brewing head is adjusted towards and into a brewing chamber or brewing chamber half or portafilter by means of a hydraulic actuator, preferably a hydraulic cylinder, provides that, during the pre-compression process, the flow or flow rate of a hydraulic fluid, in particular a brewing fluid, for hydraulically adjusting the brewing head is measured, and, depending on a predetermined limit value of the measured flow or flow rate, a control of the beverage preparation device is adapted or changed.The invention is thus based on the basic idea that conclusions about the brewing process initiated by pre-compression and about previous process steps, such as a grinding process, can be drawn via a limit value of the flow or flow rate, which can then be used to improve the further brewing or leaching process, in particular to accelerate it, and to keep the brewing or leaching processes constant and reproducible over a longer operating period or usage period of the beverage preparation device.

[0015] The method according to the invention can particularly advantageously exploit the fact that devices and methods of the generic type already incorporate means, such as flowmeters, which make it possible to detect the flow and flow rate during the hydraulic adjustment of the brewing head and during the pre-compression of the beverage substrate. The method according to the invention makes it possible not only to detect or measure the flow or flow rate, but also to adjust or modify the control of the beverage preparation device depending on at least one predetermined limit value, which is defined, at least indirectly, via the flow or flow rate.

[0016] In other words, this means that the inventive method not only achieves reproducible pre-compression of the beverage substrate, particularly regardless of the quantity or volume of the beverage substrate, but also allows the current brewing process following pre-compression and the longer-term repetitions of brewing processes to be adapted, specifically depending on or in response to the quantity or volume of beverage substrate used, in particular coffee bean flour, in order to carry out individual brewing processes faster and to be able to perform the individual brewing processes with high reproducibility over a longer period of use of the beverage preparation device.

[0017] The method advantageously employs a control unit, for example, a central control unit of the beverage preparation device, which controls parts of the beverage preparation device or the entire beverage preparation device or supplies it with corresponding control commands. This control unit can preferably be operatively connected to corresponding storage means in which parameters, profiles, limit values, and the like for controlling the beverage preparation device are stored.For the present invention, and in particular the method according to the invention, it can be particularly advantageous if the control device is configured to detect and evaluate a flow of hydraulic fluid, in particular brewing fluid, for the hydraulic adjustment of the brewing head via the hydraulic actuator, in particular to compare it with predetermined limit values, for example from the storage means, in order to change control commands, adjust control parameters and / or influence the control of the beverage preparation device when corresponding limit values ​​are reached, exceeded or fallen below.

[0018] According to a first advantageous embodiment, it can be provided that the limit value, depending on which the control of the beverage preparation device is adjusted or changed, is defined as a lower limit for a flow rate or flow, and that when the lower limit is undercut by a flow rate or flow for hydraulic adjustment of the brew head, the control of the beverage preparation device is adjusted or changed.

[0019] Typically, hydraulic actuators, such as hydraulic cylinders, used to adjust the brew head and pre-compress the beverage substrate, for example in a brewing chamber or portafilter, are supplied by corresponding hydraulic pumps or fluid pumps. These pumps, or combinations of pumps and hydraulic actuators, especially hydraulic cylinders, have a fundamental characteristic: the flow through the pump and / or through a supply line to the hydraulic actuator decreases when the internal pressure in the hydraulic actuator, particularly in the hydraulic cylinder, increases, for example, due to a correspondingly opposing external pressure.This means that when the hydraulically adjustable brew head comes into contact with the beverage substrate in the brewing chamber or portafilter, and further adjustment of the brew head causes pre-compression of the beverage substrate, increasing back pressure is exerted on the hydraulic actuator, which in turn leads to a corresponding internal pressure. This, in turn, causes the flow rate or flow rate supplied by the pump to decrease. This characteristic behavior of the flow rate or flow rate can be used to determine whether sufficient pre-compression has been achieved or is imminent. This, in turn, allows further information about the current brewing or pre-compression process to be generated or calculated, so that, for example, the amount of beverage substrate used, such as ground coffee, can be deduced.

[0020] The measured or determined quantity or volume of ground coffee used can be used both for the current brewing process and over a longer period, thus for a multitude of brewing processes, to accelerate and maintain the reproducibility of the brewing process, as will be described in detail below. Therefore, falling below a threshold that indicates the completion or near completion of the pre-compaction process, and thus allows conclusions to be drawn about the quantity or volume of ground coffee used, is particularly useful for optimizing the current brewing process, a subsequent brewing process, or a series of many subsequent brewing processes.

[0021] In a further, particularly advantageous embodiment of the method, the limit value can be defined as a saddle point in the flow or flow rate, and the control is adjusted or changed when the saddle point is passed. The saddle point in the flow or flow rate can, for example, represent a moment when, after successful and completed pre-compression, a valve between a hydraulic actuator, in particular a hydraulic cylinder, for adjusting the brew head and a brew chamber or a brew head immersed in a portafilter has been opened, and then, after the preceding decrease in flow due to the pressure increase (see above), the flow increases again because the pressure inside the hydraulic cylinder also decreases again or at least no longer increases, and simultaneously fluid, preferably brew fluid previously used as hydraulic fluid, flows out.

[0022] In this case, the end of the pre-compression process and the beginning of a brewing or leaching process can be clearly identified or determined by measuring the flow rate. This detection is particularly well-suited for gaining or generating knowledge about the pre-compression and brewing processes and for adjusting the control system accordingly.

[0023] In a further, particularly preferred embodiment of the method, it can be provided that, in response to falling below or exceeding the limit value, the control of a brewing fluid pump and / or the control of a heating device for the brewing fluid is modified. It is already known in the prior art that different brewing profiles for different beverages are stored in a corresponding beverage preparation device, for example as data sets in the aforementioned storage media, which are then used by a control device and converted into control commands or control pulses in order to control the individual assemblies and components of the beverage preparation device accordingly.

[0024] Brewing profiles can, but by no means exclusively, include the specific control of a brewing fluid pump and / or a heating device for the brewing fluid. With the method according to the invention, which detects or determines the progress or end of the pre-compression process by measuring and comparing the flow or flow rate with a predetermined limit value, it is therefore particularly advantageous to control the components, especially the heating device and / or the brewing fluid pump, immediately after the completion of the pre-compression process in order to operate them according to a desired and predetermined brewing profile.This allows for improvements in the quality of the dispensed beverage and a reduction in the preparation or brewing time, as the desired brewing profile can be initiated and executed immediately after the desired pre-compression state of the beverage substrate is reached, and potentially simultaneously with the automatic opening of the brewing fluid supply to a brewing chamber or portafilter. Depending on the definition of the threshold, the initiation of a brewing profile can occur immediately or with a predetermined time delay after the threshold is reached by the flow rate.

[0025] According to a further, particularly advantageous embodiment of the method, it can also be provided that during the pre-compression process, the absolute value of the hydraulic fluid flowing until the limit value is reached, or the time until the limit value is reached, is measured. In other words, it can be useful and advantageous not only to identify or determine the moment when the predetermined limit value is exceeded or fallen below by the device, in particular by a control unit, but also to determine or record the flow of hydraulic fluid up to that moment and / or the corresponding time frame or period from the initiation of the hydraulic adjustment of the probe head to the detection of exceeding or falling below the limit value.This allows for precise and particularly easy determination of the amount of beverage substrate present in the brewing chamber or portafilter, without the need for additional measuring equipment. This, in turn, advantageously enables further optimization of individual brewing processes as well as the optimization of continuous operation in the sense of numerous individual brewing processes carried out over a long period.

[0026] According to an advantageous embodiment, it can be provided that, depending on the detected absolute value of the quantity or volume of the hydraulic fluid and / or the measured time to reach the limit value, the control of a brewing fluid pump and / or the control of a heating device for the brewing fluid is changed or adjusted. This means that the brewing profiles already discussed above, which, in addition to the control of the brewing fluid pump and / or a heating device for the brewing fluid, for example a thermoblock, may contain further parameters and control specifications, can not only be started optimally, in a time-saving and quality-assuring manner by the method according to the invention, but can also, or alternatively, be adapted and optimized taking into account the quantity of beverage substrate used.

[0027] For example, depending on the determined or calculated amount of beverage substrate, which is ascertained via the timing or absolute value of the hydraulic fluid flow, pre-brewing can be optimized with regard to the duration, inflow rate of the brewing fluid, and subsequent interruption of the brewing fluid supply, depending on the amount of beverage substrate. Other parts or parameters of a brewing profile can also be adjusted and optimized in a similar manner.

[0028] According to another, equally desirable embodiment of the method, it can be provided that, depending on the absolute value of the quantity or volume of the hydraulic fluid and / or the measured time to reach the limit value, the control of at least one valve, preferably a pressure relief valve of the hydraulically adjustable brew head and / or the hydraulic actuator, is adjusted. The end of a beverage dispensing or the end of a brewing process generally includes draining or dehumidifying the brewed or extracted beverage substrate, which in this state is also called pomace.The control system can thus be advantageously adapted and adjusted to the amount of beverage substrate, ensuring a dewatering phase of the coffee grounds that is as short as possible, yet sufficiently long, before the hydraulically adjustable brew head is released for subsequent removal or ejection of the grounds. Depending on the amount of beverage substrate, especially the ground coffee, in the portafilter or brewing chamber, the drainage time before the valve opens to release the hydraulically adjustable brew head can be longer or shorter. For smaller amounts of beverage substrate, the drainage time can be longer than for larger amounts.This ensures that the time required for each brewing process or beverage dispensing is optimally adapted to the amount of beverage substrate used or available, while simultaneously optimizing the dehumidification or dewatering of the pomace.

[0029] In a further, particularly preferred embodiment of the method, it can be provided that, depending on the absolute value of the quantity or volume of the hydraulic fluid and / or the measured time required to reach the limit value, the control of a grinding unit of the beverage preparation device or of a data-connected, external grinding unit is modified. In both fully automatic coffee machines and hybrid beverage preparation devices, which, for example, combine a removable and interchangeable portafilter with an integrated grinder or grinding unit, it is important for the long-term consistency of the quality or properties of certain beverages that the grinding unit produces and / or dispenses the same or the predetermined quantity of beverage substrate with each dispensing and / or each production of beverage substrate, for example, when grinding coffee beans into coffee grounds.This also applies to device or machine concepts in which a data connection, for example via WLAN, Bluetooth®, NFC or the like, is established between a beverage preparation device and an external grinding unit, enabling communication and mutual influence.

[0030] However, due to different types of substrate precursors, especially coffee beans, and due to wear and tear or unintentional adjustment of the grinding unit, for example by vibrations, shocks, or the like, the actual quantity of beverage substrate dispensed (actual quantity) can deviate from a predetermined or desired quantity of beverage substrate (target quantity) over time. To remedy this problem, a further, particularly advantageous embodiment of the method according to the invention provides that, depending on the absolute value of the quantity / volume of the hydraulic fluid and / or the measured time to reach the limit value, the control of a grinding unit of the beverage preparation device or of a data-connected, external grinding unit is modified.Primarily, the absolute value of the quantity or volume of hydraulic fluid, particularly brewing fluid, conveyed by the hydraulic actuator, as explained above, allows for a direct or at least indirect conclusion to be drawn about the quantity of beverage substrate present in the brewing chamber or portafilter. This quantity can then be compared, for example by a central control unit, with the quantity that the grinding unit is intended to produce and / or dispense for the product / beverage selected or requested by the user.If a deviation is identified between the actual quantity of beverage substrate and the specified or desired quantity that exceeds a predetermined tolerance threshold, such as 5%, the inventive method allows a control parameter for the internal or connected external grinding unit to be adjusted, preferably via a central control device. This adjustment then enables the control of the grinding unit to be adapted for subsequent orders of the same beverage / product or when the same recipe, which includes a grinding profile or grinding parameters for the grinding unit in addition to the brewing profile, is used. Primarily, the grinding process can be varied during which the grinding unit produces and / or dispenses beverage substrate. However, parameters or control variables can also be changed, which then, for example, influence or alter the grind size.

[0031] In this embodiment of the method, manual filling of the brewing chamber or the portafilter can advantageously take place, or an external grinding unit not connected to data technology can be used, without an unwanted, unintentional detection of a maximum discrepancy regarding the amount of beverage substrate available.In a further, advantageous embodiment, it can be provided that influencing or changing the control of the grinding unit or a data-technically connected, external grinding unit in reaction to or depending on the absolute value of the quantity of hydraulic fluid or the measured time to reach the limit value only occurs if the grinding unit was previously active, for example within a period of 0s to 100s, or if the grinding unit was activated by a control device, for example a central control device, and / or if a corresponding activation was archived or stored in a memory along with a corresponding timestamp.This ensures that manual loading of the brewing chamber or portafilter, or the use of external grinding units that are not connected to the data system, are disregarded when compensating or correcting the internal or data-connected grinder.

[0032] Another particularly desirable embodiment of the method can also provide that, in response to the detection of the limit value, the hydraulic actuator is released, preferably immediately, without initiating a brewing process. This release of the actuator preferably returns the adjustable brew head to its initial position, in particular by raising it. This method variant can be implemented particularly advantageously if a user or operator has previously activated or selected a double brewing process for the preparation of two beverages, or if another user input or setting indicates, or if it is foreseeable, that a particularly large quantity of beverage substrate is to be filled into the brewing chamber or portafilter, for example, produced and dispensed by the grinding unit.

[0033] In such a case, it may be advantageously provided that, for example in the case of an integrated grinding unit, the grinding unit first dispenses a first part or half of the beverage substrate, which is then compacted via automatic hydraulic pre-compression, before a second part or half of the beverage substrate is dispensed or filled, which is then compacted again in a pre-compression process before the brewing or leaching process takes place.By using staged or divided pre-compaction with two or more pre-compaction processes, each applying a portion of the total beverage substrate, not only can a larger quantity of beverage substrate be filled into a brewing chamber or portafilter of a predetermined volume, but a more uniform pre-compaction is also achieved. This is because otherwise, with a large quantity of beverage substrate, the pre-compaction cannot be uniform across the entire height or column of the beverage substrate in the portafilter or brewing chamber. Furthermore, this opens up the possibility of processing different beverage substrates for a single beverage preparation.In principle, it would be possible to first compact a decaffeinated beverage substrate, then, upon reaching the limit value, release the hydraulic actuator, reset the brew head, and thus have the opportunity to refill or top up a caffeinated beverage substrate, which would then be compacted again using a hydraulic pre-compaction process, and only after the second pre-compaction process, upon reaching the limit value of the flow or flow rate, would an automatic or self-controlled opening of a brewing fluid inlet be triggered, and the controls and control adjustments described above, which may be advantageously triggered by reaching the limit value, would be carried out.

[0034] Details and advantageous embodiments of the method according to the invention are explained below with reference to the merely schematic, exemplary drawings.

[0035] It shows: Fig. 1: Exemplary time profiles of flow rates in a method according to the invention; Fig. 2: A schematic setup of a beverage preparation device operated with a method according to the invention.

[0036] In the Fig. 1 The flow rate in a method according to the invention is plotted as a function of time, with the different graphs 01 relating to different brewing processes. The method according to the invention is used in beverage preparation devices that have a hydraulic pre-compression unit and are operated with a hydraulic pre-compression method in which a hydraulic actuator, preferably a hydraulic cylinder, is moved to adjust a brewing head and press a brewing head onto a beverage substrate.The inventive method, as will be described in detail below, is particularly preferably implemented with beverage preparation devices in which the hydraulic fluid used to actuate the hydraulic actuator during the hydraulic pre-compression process is (partially) identical to the brewing fluid used to brew the beverage substrate. The hydraulic fluid / brew fluid initially flows into the hydraulic actuator, in particular the hydraulic cylinder, causing the adjustment of the brewing head and the pressing of the brewing head against the beverage substrate. After completion of the hydraulic pre-compression process, the fluid is at least partially used, for example, via appropriate fluidic connections and controls – preferably via valve circuits – to exit / flow out of the hydraulic actuator and brew or extract the beverage substrate. Corresponding devices are disclosed in detail in patent application DE 10 2021 123 545.

[0037] The flow rate of the brewing fluid / hydraulic fluid is recorded, for example, by a flowmeter located between a fresh water tank or fresh water connection and a brewing unit of the beverage preparation device. The flow rate can be roughly divided into four sections. In the first section 02, which preferably lasts until time t1, the hydraulic pre-compression of the beverage substrate takes place. In section 03, between times t1 and t2, the brewing process occurs, during which brewing fluid with a predetermined brewing profile, preferably specifying a flow rate or flow profile and a temperature or temperature profile, is introduced into a brewing chamber containing the pre-compressed beverage substrate. In the third section 04, between times t2 and t3, dehumidification or dewatering of the beverage substrate or pomace takes place.In the fourth or final section 05, between times t3 and t4, the hydraulic actuator, in particular the hydraulic cylinder for adjusting the brew head, is released and returned to its initial position. This return can occur, for example, against a mechanical preload, preferably in the form of a spring or springs.

[0038] In the first section 02, it can be seen that the flow rate of the hydraulic fluid / brewing fluid initially increases and, after a corresponding conveying device, such as a pump, starts up, initially reaches a maximum value of 06. As soon as the brew head, for example, an end face of the brew head, comes into contact with the beverage substrate and, during further adjustment or movement of the brew head, exerts a force to pre-compact the beverage substrate, a corresponding counterforce is created on the brew head and the hydraulic actuator. This causes the internal pressure in the actuator to rise, and consequently, the counterpressure also acts on the pump, resulting in a decrease in the flow rate during the pre-compaction process.The decrease itself, i.e., for example, the slope of the curve during the decrease 07 or a local minimum or a local saddle point 08 of the flow rate, can be defined as a limit value in order to adjust or change the control of the beverage preparation device according to the invention. The saddle point 08 generally results from the opening of a valve through which brewing fluid / hydraulic fluid can flow from the hydraulic actuator into the brewing chamber for pre-compression. This automatically initiates or starts the brewing process, for example, with a corresponding pressure relief valve.

[0039] However, when the pressure relief valve is open, a slight pressure drop also occurs in the hydraulic actuator. This, along with the outflow of hydraulic fluid / brew fluid, causes the flow rate to increase again at the beginning of section 03 after reaching a minimum, ultimately leading to the formation of saddle point 08. According to the invention, saddle point 08 can, for example, be detected, and the control of the beverage preparation device can be adjusted or modified in response to this detection.

[0040] On the one hand, the value of the saddle point or the flow rate at the saddle point can be used to modify or adjust the control system. Alternatively or additionally, the point in time at which saddle point 08 is reached, namely time t1, can be recorded and taken into account when adjusting or modifying the control system. For example, in response to reaching and recognizing saddle point 08 as a limit value, a brewing profile can be initiated, which might involve controlling a pump accordingly, for example with a constant or variable supply voltage, and serves to achieve a predefined flow rate characteristic in the brewing chamber.Furthermore, if necessary, in response to the detection of saddle point 08 as a limit value and the associated initiation or activation of a brewing profile as an adjustment of the control of the beverage preparation device, a predetermined control, in particular voltage supply of a heating device for heating the hydraulic fluid / brewing fluid, may take place.

[0041] Furthermore, by detecting the value of saddle point 08 and / or by recording the time, and alternatively or additionally based on the absolute value of the recorded flow until saddle point 08 is reached, the amount of beverage substrate in a brewing chamber or portafilter can be determined. This allows the control of the beverage preparation device to be adjusted so that the duration of section 04 for dehumidifying or draining the pomace between times t2 and t3 is modified, in particular by varying time t3. It can be provided that for large quantities of beverage substrate, the interval between t2 and t3 is shortened by advancing time t3, and conversely, for small quantities of beverage substrate, time t3 is delayed.Similarly, the respective brewing profile can be adjusted based on the determined / calculated amount of beverage substrate, and the control can be influenced or changed accordingly.

[0042] Fig. 2 Figure 10 shows a schematic representation of a system or beverage preparation device 10 with which the method according to the invention can be carried out or which can be operated with the method according to the invention.

[0043] The beverage preparation device 10 comprises a reservoir 11 in which fresh water is stored as hydraulic fluid and brewing fluid. From the reservoir 11, the fresh water can be pumped via the pump 12 to a heating unit 13, the flow or flow rate being measured or recorded by a flowmeter 14. From the heating unit 13, the water, which may already be heated, flows into a hydraulic actuator 15, which may, for example, be designed as a hydraulic cylinder. The hydraulic actuator 15 is configured to adjust a brewing head 16 and, in particular, to insert it into a brewing chamber or a portafilter holder 17 in order to close a brewing chamber 18 and to compress the beverage substrate 19 contained therein.The adjustable brew head 16 comprises an outlet face 20 that comes into contact with the beverage substrate 19 and compresses it within the brewing chamber 18, provided that an increasing amount of hydraulic fluid is present in the hydraulic actuator 15 and a correspondingly higher internal pressure is generated. Above a certain overpressure in the hydraulic actuator 15, a fluid connection 21 to the brewing chamber 18 is opened, and the hydraulic fluid / brewing fluid, preferably in the form of heated water, can flow from the hydraulic actuator 15 into the brewing chamber 18 and from there out via an outlet 22.

[0044] The device 10 comprises a central control unit 23, which is operatively connected to various components of the device 10, in particular to a storage medium 24, as well as to the flowmeter 14, the pump 12, the heating device 13, and a valve arrangement 25 of the hydraulic actuator 15, in such a way that the control unit 23 is able to extract, in particular load, predetermined control variables, control parameters, and control profiles from the storage medium 24 and, based thereon, issue and / or adapt control commands or control instructions to the operatively connected components. Accordingly, in the method according to the invention, it can be provided that the flow or flow rate through the flowmeter 14 is continuously or periodically checked / monitored by the control unit 23 and compared with correspondingly predefined limit values, which can, for example, be stored in the storage medium 24.

[0045] Upon detection of exceeding or falling below the limit value, or upon detection of a saddle point 08 as the limit value, the control unit 23 can again load corresponding control parameters from the storage medium 24 and initiate the control and / or adjust control parameters and, based on this, adapt the control of the beverage preparation device 10. For example, upon detection of the saddle point 08 according to the Fig. 1 In response to the detection of the saddle point 08, a brewing profile is loaded from the storage medium 24 and used to control the pump 12 and / or the heating device 13. It may be provided, for example, that individual parameters of the brewing profile are not static, but are adjusted or influenced depending on when the limit value was reached, how or in what form the limit value was undercut or exceeded.

[0046] Furthermore, the control unit 23 can also control the valve unit 25, for example, to vary time t3, which defines the duration of the dehumidification or drainage phase. At or from time t3, the hydraulic actuator 15 is released via the valve unit 25 and the brew head 16 is reset, thus ending the drainage / dehumidification process. The control unit 23 can also adjust the valve unit 25 in the control system so that, in response to reaching a limit value, particularly in the case of a corresponding exceedance or fall below a limit after hydraulic pre-compression, the hydraulic actuator 15 is immediately released. This allows for the double dispensing of a beverage with a corresponding amount of beverage substrate 19, or the intake of two or more batches of beverage substrate before initiating a brewing process, whether caused or required by other factors.

[0047] Furthermore, the control unit 23 can be operatively connected to a grinding unit 26 and effect grinding compensation, whereby the hydraulic pre-compression process and the information about exceeding or falling below the predefined limit value, optionally in conjunction with other information about the limit value, such as the absolute value of the flow rate when the limit value is reached or time t1 at which the limit value is reached, fallen below, or exceeded, are used to adjust the control of the grinding unit 26 so that the quantity of beverage substrate 19 present in the brewing chamber 18 corresponds to the quantity that is to be dispensed and / or produced by the grinding unit. This adjustment can take place for both internal grinding units 26 and for external, data-connected grinding units.Furthermore, the adjustment can take into account whether an internal or external, data-connected grinding unit has been activated in the recent past, for example within the last 100s, in order to prevent "misadjustments" during manual loading or the use of external, unconnected grinding units. Reference sign

[0048] 02 First section 03 Second section 04 Third section 05 Fourth section 06 Maximum value 07 Acceptance 08 Saddle point 10 Beverage preparation device 11 Storage container 12 Pump 13 Heating device 14 Flow meter 15 Hydraulic actuator 16 Brew head 17 Portafilter holder 18 Brew chamber 19 Beverage substrate 20 Outlet face 21 Fluid connection 22 Outlet 23 Control device 24 Storage medium 25 Valve assembly 26 Grinding unit t1 time t2 time t3 time t4 time

Claims

1. A method for operating a beverage preparation device (10), in particular a coffee machine, comprising a hydraulic pre-compacting unit for compacting a beverage substrate (19), preferably ground coffee, prior to a brewing or leaching process using a brewing fluid, preferably water, in which a brew head (16) is adjusted by a hydraulic actuator (15), preferably a hydraulic cylinder, during a pre-compacting process, characterized in that during the pre-compacting process, the flow or the flow rate of a hydraulic fluid, in particular the brewing fluid, for adjusting the brew head (16) is measured and a control of the beverage preparation device (10) is adjusted or changed as a function of a predefined limit value of the measured flow or the measured flow rate.

2. The method according to claim 1, characterized in that the limit value is defined as a lower limit for a flow or a flow rate, and the control is adjusted or changed when the flow or the flow rate drops below said lower limit.

3. The method according to claim 1 or 2, characterized in that the limit value is defined as a saddle point (08) of the flow or the flow rate, and the control is adjusted or changed when the flow or the flow rate passes the saddle point (08).

4. The method according to any one of the preceding claims, characterized in that in response to the fact that the flow or flow rate drops below or exceeds the limit value, a control of a pump (12) and / or the control of a heater (13) for the brewing fluid is changed.

5. The method according to any one of the preceding claims, characterized in that during the pre-compacting process, the absolute value of the amount or of the of volume of the hydraulic fluid needed to reach the limit value or the time (t1) needed to reach the limit value is measured.

6. The method according to claim 5, characterized in that the control of a pump (12) and / or the control of a heater (13) for the brewing fluid is changed as a function of the absolute value of the amount or of the volume of the hydraulic fluid and / or the measured time (t1) needed to reach the limit value.

7. The method according to any one of claims 5 or 6, characterized in that a control of at least one valve, preferably a relief valve of the hydraulically adjustable brew head (16), is adjusted as a function of the absolute value of the amount or of the volume of the hydraulic fluid and / or the measured time (t1) needed to reach the limit value.

8. The method according to any one of claims 5 to 7, characterized in that a control of the relief of the hydraulic actuator (15) is adjusted, preferably via at least one valve, particularly preferably a relief valve of the hydraulic actuator (15), as a function of the absolute value of the amount or of the volume of the hydraulic fluid and / or the measured time (t1) needed to reach the limit value.

9. The method according to any one of claims 5 to 8, characterized in that a control of a grinding unit (26) of the beverage preparation device (10) or a data-linked external grinding unit is changed as a function of the absolute value of the amount or of the volume of the hydraulic fluid and / or the measured time (t1) needed to reach the limit value.

10. The method according to claim 9, characterized in that the control of the grinding unit (26) of the beverage preparation device (10) or a data-linked external grinding unit is not changed unless a grinding process has been carried out and / or documented in a predefined period of time, preferably between 0 s and 100 s, prior to the detection of the drop below or the exceedance of the limit value.

11. The method according to any one of claims 1 to 9, characterized in that in response to the detection of the limit value when no brewing process has been carried out, the hydraulic actuator (15) is relieved, preferably immediately.