METHOD FOR OPERATING A FULLY AUTOMATIC COFFEE MACHINE AND FULLY AUTOMATIC COFFEE MACHINE

Description

[0001] The present invention relates to a method for operating a fully automatic coffee machine according to the preamble of claim 1, and to a fully automatic coffee machine according to the invention.

[0002] Experts are familiar with fully automatic coffee machines that produce various coffee varieties using the espresso method – i.e., under pressure.

[0003] Traditional machines for brewing filter coffee have also been around for a long time. Due to the relatively slow and low-pressure brewing process, this method produces coffee with a very balanced taste and aroma.

[0004] Traditional espresso brewing allows for a rapid release of aromas. The brewing process, which in a fully automatic coffee machine typically takes less than 30 seconds for a cup of coffee, releases more essential oils and aromas due to the pressure of approximately 7.5-9 bar, while the short brewing time results in less caffeine, tannins, and bitter substances. There are enthusiasts of both types of coffee.

[0005] DE 42 40 175 C1 discloses a brewing unit with a self-operating coffee machine. The type of coffee preparation is selected by the brewing position of the brewing piston. Café crème is prepared by tamping, whereas filter coffee is prepared without tamping. A similar setting for selecting between café crème and filter coffee is described in DE 33 16 157 A1.

[0006] EP 0 909 542 A1 reveals a coffee machine for optionally brewing filter coffee and espresso coffee.

[0007] US 6 513 419 B2 and WO 2007 / 060 694 A1 each disclose a coffee machine for preparing various types of coffee, including filter coffee.

[0008] The aforementioned documents do not reveal any division of the filter coffee brewing process into multiple brewing phases. Therefore, a balanced extraction of the respective flavor compounds cannot be achieved.

[0009] As a further state of the art, the generic DE 20 2016 008 296 U1 is cited, which, however, does not relate to the production of filter coffee.

[0010] German patent DE 102018 116 306 A1 discloses various characteristics of filter coffee in contrast to other types of coffee, such as espresso. A preparation of filter coffee with multiple brewing phases is not disclosed; rather, coffee powder is added in parallel with the brewing process, whereby the amount of water / volume flow is constant or preferably variable and can preferably also be monitored once or continuously.

[0011] The invention is therefore based on the objective of operating a coffee machine in such a way that coffee with a taste comparable to filter coffee is provided.

[0012] The invention solves the problem by means of an operating method with the features of claim 1 and by providing a fully automatic coffee machine according to the invention.

[0013] A method is then created for producing a coffee beverage with a filter coffee taste by a fully automatic coffee machine, wherein the fully automatic coffee machine has at least one brewing unit with a brewing chamber and a piston movable in the brewing chamber, in particular linearly displaceable, for adjusting a brewing chamber volume, wherein the method comprises at least the following steps: a. Filling the brewing chamber with ground coffee; and b. supplying water to the brewing chamber for the purpose of extraction during a brewing process, wherein at least the piston is arranged during at least one brewing phase of the brewing process in a position in which the brewing chamber volume is larger than the volume of the ground coffee in a poured state in the brewing chamber after filling according to step a, wherein the brewing process has several brewing phases in which water is passed through the ground coffee at different flow rates relative to the brewing phases, and wherein the change between the brewing phases is effected by measuring and / or determining a physical quantity, in particular the conductivity, the refractive index and / or the quantity and / or volume of ground coffee and / or water supplied and / or the quantity of coffee discharged, wherein furthermore the fully automatic coffee machine has a bypass line from a hot water boiler to a dispensing unit with one or more control elements, wherein a dispensing of hot water,preferably simultaneously with the brewing process and / or the dispensing of coffee from the brewing unit, in order to achieve a predetermined coffee volume.

[0014] Such fully automatic coffee machines are known in themselves, but are usually not used to make filter coffee, but rather to make espresso or espresso-based drinks.

[0015] The piston is moved mechanically by an actuator, e.g. motor-driven or hydraulic, thereby adjusting the brewing chamber volume.

[0016] The poured state refers to the bulk volume that results when an amount of coffee grounds corresponding to the amount of coffee grounds in the brewing chamber from step a. is present in an uncompacted state.

[0017] In the first position of the piston, the volume of the brewing chamber is expanded to such an extent that a suspension of coffee grounds and water can be present, in which the coffee grounds can be settled at the bottom of the brewing chamber and / or floating in the suspension.

[0018] The coffee grounds, when poured, can be essentially uncompacted at the beginning of step b. This essentially means that slight compaction of the coffee grounds is possible for the purpose of shaping them. Typically, a pour has a conical shape. However, shaping into a cylindrical form can occur without significantly compressing the volume of the coffee grounds mechanically. In contrast, non-mechanical compression and / or compaction of a pour of coffee grounds—that is, compression or compaction without an externally applied mechanical force—is inherent to the brewing process due to the swelling of the coffee grounds.

[0019] The coffee grounds can be compacted slightly after filling, and especially before brewing. In a preferred embodiment, however, the coffee grounds are essentially uncompacted. This means that, compared to a poured state (i.e., loose ground), the coffee grounds are compacted by less than 15% by volume, and in particular by less than 10% by volume.

[0020] This negligible compaction can occur as part of shaping the coffee grounds, for example to give the coffee grounds a cylindrical basic shape, in which the extraction is more uniform than with a typical pouring cone shape.

[0021] The water can then flow through the coffee grounds during at least one brewing phase without any further mechanical pressure being exerted on the coffee grounds compared to their initial state. However, due to the swelling of the coffee grounds, some compaction can still occur without any external mechanical pressure being applied. In particular, water added in step b. can flow through the coffee grounds essentially without any pressure being exerted on them.

[0022] The piston can thus be moved or adjusted to a second position, in which it shapes the coffee grounds, preferably before the brewing process. This allows for an even distribution within the brewing chamber, depending on the amount of coffee grounds.

[0023] Furthermore, and also optionally, the piston can be fully retracted in the first position, thereby maximizing the volume of the brewing chamber. Individual brewing phases can be performed in this fully extended position. An air gap may also exist between the suspension and the piston's end face. However, this first position does not necessarily have to represent the fully extended state; it can also be less.

[0024] In addition to the main brewing phase, further brewing phases can also be provided. Preparatory or post-processing steps such as coffee grinding or subsequent cleaning, e.g., by CIP (clean in place), can also be part of the method according to the invention. With CIP cleaning, parts do not need to be disassembled, and cleaning can be carried out automatically within the fully automatic machine.

[0025] This method makes it easy to implement filter coffee brewing in a fully automatic coffee machine. The free water volume allows, among other things, the coffee grounds to float. Furthermore, the coffee grounds, in their uncompacted state, can be more easily surrounded by the water.

[0026] For a balanced extraction of the respective flavor compounds, it is advantageous if the brewing process consists of several brewing phases, in each of which water is passed through the coffee grounds at different flow rates, depending on the brewing phase.

[0027] According to the invention, the change between brewing phases is preferably achieved by measuring and / or determining a physical quantity, in particular the conductivity, the refractive index, and / or the quantity of ground coffee and / or water supplied, and / or the quantity or volume of coffee removed or discharged. This allows for the maximum extraction of flavor compounds. Coffee is a natural product whose flavor compounds can vary depending on the growing region, roasting process, storage, etc. A preferred variant is a water-quantity-controlled change depending on the dispensing quantity, taking into account the quantity of ground coffee.

[0028] Advantageous embodiments of the invention are the subject of the dependent claims.

[0029] As previously described, the piston can remain in a first position during the brewing process, which is subsequently also described as the rest position.

[0030] Preferably, the brewing chamber volume at the beginning of step b can be at least 50% larger, preferably twice as large, as the volume of the coffee grounds in the poured, especially uncompacted, state.

[0031] Furthermore, it is preferred and advantageous that the brewing chamber is constructed such that at the beginning of step b, only the ground coffee is arranged within the brewing chamber. Rather, the free volume of the brewing chamber borders the bed of ground coffee and is filled with hot water in step b.

[0032] In this context, it is particularly advantageous if the brewing process a) a first brewing phase with a first flow rate and b) a second brewing phase with a second flow rate and / or preferably a third brewing phase with a third flow rate, where the second flow rate can be smaller than the first and / or third flow rate.

[0033] It is advantageous to divide the brewing process into at least 2, preferably 3 brewing phases, each of which can be assigned one of at least 2, preferably 3, different flow rates.

[0034] For example, the aforementioned second brewing phase can be designed as the main brewing phase. Furthermore, the first brewing phase can be designed as the pre-brewing phase and the third as the post-brewing phase. However, this classification or sequence is not mandatory. Thus, the second brewing phase can also be the first or the last brewing phase of the brewing process.

[0035] These process phases advantageously occur sequentially and are particularly preferably carried out immediately one after the other.

[0036] The second flow rate is preferably smaller than the third flow rate, which in turn is preferably smaller than the first flow rate.

[0037] The flow rate for at least one brewing phase of the brewing process can be comparatively slow and be less than or equal to 10 ml / s, preferably 2-5 ml / s.

[0038] Preferably, the flow rate for at least the second brewing phase of the brewing process can be 2-5 ml / s. Equally preferably, the flow rate for at least the first brewing phase of the brewing process can be 5-10 ml / s. Furthermore, the flow rate for at least the third brewing phase of the brewing process can be 10-15 ml / s.

[0039] The fully automatic coffee machine can also include a coffee grinder, the process of which involves grinding coffee beans to a predefined size for filter coffee. As is well known, the grind for filter coffee is coarser than that for espresso. Therefore, it is advantageous if the coffee machine automatically adjusts the grinder's operating parameters to the optimal grind for filter coffee when the user selects "filter coffee."

[0040] The grind size can be determined according to DIN 44 539. DIN 44 539 defines three grades for classifying the grind size. These grades define particle sizes that must constitute more than 50% of the ground material, in this case, the coffee grounds. The value x 50.3 in the measurement protocol indicates that 50% of the grind distribution is coarser and 50% is finer than the stated measured value. The determination of the individual particle size fractions is carried out using the air jet sieve method according to DIN 10 765. The aforementioned regulations refer to the version in force at the priority date of the present invention. Grind setting "fine"

[0041] All grain sizes up to a maximum of 0.25 mm account for more than 50%. Grind setting "medium"

[0042] Grain sizes between 0.25 mm and 0.71 mm account for more than 50%. Grind setting "coarse"

[0043] All grain sizes larger than 0.71 mm account for more than 50%.

[0044] For the present process, a grind size of "medium" or, preferably, "coarse" is recommended.

[0045] It is recommended that the piston shapes the coffee powder before the brewing process, so that the volume of the brewing chamber is reduced during and for this purpose.

[0046] After the initial shaping, the piston is retracted and therefore does not rest on the coffee grounds. This creates a larger brewing chamber, providing more space for the coffee grounds to expand upon contact with the water. At the same time, uncompacted coffee grounds offer lower flow resistance.

[0047] This method allows for an uncompressed flow pattern. In contrast, when brewing conventional filter coffee in a coffee filter, the coffee grounds often need time to settle, which adds to the brewing process. Furthermore, it is advantageous to retract the piston before brewing, allowing the brewing chamber volume to expand again, preferably by at least 100% compared to its volume when compressed. This ensures a slow extraction and low-pressure water flow.

[0048] It is advantageous if the piston remains in a resting position throughout the entire brewing process. The piston can also be moved during the initial brewing and / or post-brewing phases.

[0049] At least during the brewing phase, a slow extraction is recommended.

[0050] Furthermore, the fully automatic coffee machine may have a filter, e.g. a sieve and in particular a CIP-compatible permanent filter.

[0051] The brewing phases can be modified, in particular, by measuring conductivity and / or refractive index, with a sensor positioned downstream of the brewing unit so that the measurement of the finished coffee, i.e., the end product, serves as the basis for the modification. Alternatively, and preferably, the sensor can also be positioned upstream of the brewing unit to influence the properties during preparation.

[0052] A particularly advantageous way to adjust the brewing phases is by monitoring the amount of water added, taking into account the amount of ground coffee added. The amount of ground coffee added can, for example, be considered when adjusting the grinding speed. The grinding speed in mg / s at a preset grind setting can be adjusted to the amount of water for a specific volume of filter coffee, according to customer requirements.

[0053] Furthermore, the brewing pressure during the brewing process is preferably less than 2.5 bar.

[0054] Preferably, the brewing chamber is closed except for a coffee outlet during the brewing process. Optionally, a hot water inlet may also be open.

[0055] Preferably, the flow rate is adjusted in stages during the brewing process to switch between two brewing phases. Preferably, the switch between all other brewing phases of the brewing process can also be adjusted in stages.

[0056] According to the invention, a fully automatic coffee machine also comprises at least one brewing unit with a linearly displaceable piston for adjusting the volume of a brewing chamber of the brewing unit and a control and / or evaluation unit which is configured to carry out a method according to the invention.

[0057] The fully automatic coffee machine has a hot water boiler, and a flow restrictor may be installed between the hot water boiler and the brewing unit to adjust the flow rate. This allows the flow rate to be set after the first, second, and / or third brewing phase and / or any other optional brewing phases.

[0058] The flow restrictor can incorporate multiple control elements, such as valves, designed for stepwise adjustment of the flow rate to ensure a brewing process with multiple brewing phases at varying flow rates. A stepwise adjustment allows for very direct setting of a desired flow rate, whereas a stepless adjustment often results in a difficult-to-measure residual flow, leading to less than optimal dosing.

[0059] The invention will now be explained in more detail using an exemplary embodiment of a method according to the invention and with the aid of the following figures. These show: Fig. 1a a schematic diagram of a first variant of a fully automatic coffee machine according to the invention; Fig. 1b a schematic diagram of a second variant of a fully automatic coffee machine according to the invention; Fig. 1c a schematic diagram of a third variant of a fully automatic coffee machine according to the invention; Fig. 2a-g detailed views of a brewing unit of the fully automatic coffee machine with a piston in different operating positions during the execution of the method according to the invention; Fig. 3 a measurement of various physical quantities as a function of the course of the brewing process during the execution of the method according to the invention; Fig. 4 measurement diagram of an exemplary coffee extraction, e.g. based on conductivity, over a brewing process with several brewing phases according to a first embodiment of the method according to the invention; and Fig. 5 measurement diagram of an exemplary coffee extraction, e.g.based on conductivity, via a brewing process with several brewing phases according to a second embodiment of the method according to the invention.

[0060] In the Fig. 1 The basic structure of a fully automatic coffee machine according to the invention 1 is shown.

[0061] The fully automatic coffee machine 1 has a brewing unit 2 and a hot water boiler 3 as its central components. For supplying water, the fully automatic coffee machine has a water inlet 4. This can be, for example, a removable water reservoir or a connection to a water line.

[0062] Furthermore, the fully automatic coffee machine 1 has a water pump 5 for pumping the supplied water into the hot water boiler 3.

[0063] Furthermore, the fully automatic coffee machine 1 has a measuring device 6 for determining the flow rate. In the present embodiment, this device is arranged upstream of the hot water boiler 3 and enables the water inlet volume to be controlled at this position. Alternatively or additionally, an analogous measuring device for determining the flow rate can also be arranged between the hot water boiler 3 and the brewing unit 2 and / or downstream of the brewing unit 2. The measuring device 6 for determining the flow rate can advantageously be designed as a paddle wheel flow meter.

[0064] Furthermore, the inlet pipe in front of the hot water boiler 3 has a non-return valve 7.

[0065] The hot water boiler 3 then heats the supplied water to a temperature of preferably 80–96°C. Within this temperature range, the water temperature can be adjusted according to the desired hot beverage. Furthermore, the fully automatic coffee machine can have a cold water mixing line (not shown) to achieve product-specific brewing temperature adjustment. The water heated in this way is then, preferably in a metered manner, forwarded to the brewing unit 2.

[0066] If the water boiler 3 or alternatively the brewing unit 2 does not already have a dosing device implemented, a flow restrictor 8 can be provided between the water boiler 3 and the brewing unit 2 for more precise dosing of the flow rates of warm water required in the respective process steps.

[0067] The flow restrictor of the Fig. 1aThis allows for a stepped adjustment, in particular a stepped control, of the flow rate of the hot water supplied to brewing unit 2. For this purpose, the following are required: Fig. 1a Three brewing valves 8a-8c are provided, each of which can have a different cross-section and consequently represents a different flow rate into the brewing unit. Preferably, one brewing valve is open while the other two brewing valves are closed.

[0068] In the variant of Fig. 1b The flow limiter 8 is implemented by two brewing valves 8a and 8b. Here, too, at least three flow rates can be set, either by opening the individual brewing valves 8a or 8b, or by opening both valves 8a and 8b simultaneously. Preferably, in the variant of Fig. 1bThe cross-sections, and therefore the flow rate, are continuously adjustable after the valve, e.g., manually adjusted needle valves. This allows for stepless adjustment of the flow rate of a water supply that would otherwise be set in stages.

[0069] Fig. 1c Disclosing a variant in which a continuously variable valve 8d is used to adjust the flow rate, a stepwise change of the flow rates is preferred to enable direct and rapid control. Furthermore, for redundancy reasons, the stepwise variant ensures emergency operation for coffee dispensing with reduced options even if one valve fails. Additionally, the stepwise adjustment shown in Figures 8a and 8b allows for rapid inflow and outflow with clear and unambiguous switching states.

[0070] While espresso machines often use a pressure limiter at this point, a flow limiter, e.g., a throttle, preferably a variable-speed throttle, is preferable here. Alternatively, the functions of a pressure limiter and a flow limiter can be implemented together in a single control device, making the fully automatic coffee machine more versatile and able to prepare a wider variety of coffee drinks.

[0071] The brewing unit 2 preferably has a brewing chamber 12, the volume of which is adjustable by a linearly movable piston 11. The piston position is variably adjustable. Furthermore, the brewing unit 2 has a filter 15, preferably a permanent filter. The permanent filter is preferably CIP-compatible. The permanent filter can, in particular, be a micro-fine sieve. The sieve is especially preferably able to have at least 30,000 holes, preferably at least 40,000 holes, with a diameter of 1 x 10³ mm.

[0072] The brewing unit can be filled with ground coffee either manually, i.e., by directly adding the grounds, for example, via a feed chute, or by grinding whole beans immediately before feeding them into the brewing unit. For this purpose, the fully automatic coffee machine may have an integrated coffee grinder (not shown). Since ground coffee for filter coffee is usually coarser than espresso powder, it is advantageous if the integrated coffee grinder is equipped to produce a variable grind. This grind is tailored to the type of coffee and the type of filter, especially a permanent filter. Relevant parameters include, for example, the fineness of the grind and its distribution. Further details of a coffee grinder with variable grind settings can be found in DIN 44539 (in its current version at the time of this application), which is referenced in this application.The grind can be adjusted, for example, by varying the grind, speed, pressure of the grinding elements and / or the roughness of the grinding elements.

[0073] In addition to or as an alternative to the flow restrictor 8, the fully automatic coffee machine 1 can have a sensor 9, in particular a physical sensor for determining a coffee property. This sensor is preferably arranged downstream of the brewing unit 2. This coffee property can preferably be conductivity, refractive index, pressure, and / or temperature. A variant of the measurement in this context is described in detail in DE 10 2018 116 306 A1, to which reference is hereby made. Alternatively, and particularly preferably, the sensor can also determine the volumetric flow rate of coffee leaving the brewing unit.

[0074] Finally, the coffee is forwarded to a dispensing unit 10. Additionally, the fully automatic coffee machine 1 may have further shut-off and / or diverting valves at various positions.

[0075] In particular, the fully automatic coffee machine has a bypass line 17 between the hot water boiler 3 and the dispensing unit 10 for supplying hot water to the dispensing unit without first passing it through the brewing unit 2. Specifically, the bypass line 17 allows for a reduction in coffee brewing time due to the parallel supply of hot water to the coffee. It is particularly important to note that during a post-brewing phase, hardly any flavor compounds are extracted, so the brewing time is shortened to the desired volume by supplying hot water. No bitter substances are introduced via the bypass line 17, as can occur with longer extraction times in the brewing unit. Nevertheless, the desired volume can still be achieved.

[0076] The hot water supply to the dispensing unit can be achieved at several predefined flow rates, with control elements 16, e.g., bypass valves 16a and 16b, being provided for setting a flow rate. The flow rate and the inlet volume can preferably be determined based on the values ​​measured by the sensor 9 or based on the flow rates.

[0077] The operation of the brewing unit 2 and / or the hot water boiler 3 is controlled by a control and / or evaluation unit 13. The control and / or evaluation unit preferably has a processing unit and a data storage unit on which one or more data sets or databases are stored, which are retrieved when the method according to the invention is carried out.

[0078] The inventive method for producing a coffee beverage with the characteristics of filter coffee is carried out in several steps. The brewing unit 2, designed as a piston unit, and other core components of the fully automatic coffee machine are used for fully automatic filter coffee production.

[0079] A predefined quantity of ground coffee is fed into the brewing chamber 12, and hot water is passed through it at a low flow rate while the piston is withdrawn. The coffee extracted under these conditions exhibits the characteristic features of freshly brewed filter coffee. Investigations have shown that the resulting coffee beverage yields a directly comparable result to filter coffee production, e.g., using a glass filter. The inventive method is described in detail below with reference to one embodiment.

[0080] The first step involves a user entering their beverage order. This order can be submitted electronically, for example via a mobile app, or by activating a control element, such as a control panel or a button on the fully automatic coffee machine.

[0081] Then, in a second optional step, coffee beans are ground to an optimal size for filter coffee using the coffee grinder. With machines that have multiple storage tanks, for example for espresso beans or coffee beans, it is also possible to optionally select the type of bean that is fed into the coffee grinder.

[0082] Alternatively, ground coffee can be added to the brewing unit by direct insertion - before or after the first step.

[0083] In a third step Fig. 2a-2c The brewing chamber 12 of the fully automatic coffee machine 1 is filled. This is done, for example, by opening a slide 14. Fig 2a and 2b, the brewing chamber 12 opened and ground coffee flour, compare Figs. 2b and 2c , supplied. In Fig. 2c The coffee grounds are then in a cone shape.

[0084] In a fourth step, as shown in Fig. 2c The brewing chamber is then closed, e.g., by actuating the slide 14, and the brewing chamber 12 is sealed. Depending on the amount of coffee grounds, the piston 11 of the brewing unit 2 can be briefly actuated to tamp the coffee grounds. This takes place in Fig. 2d The coffee grounds are only slightly compacted, but merely formed into a cylindrical shape to achieve a more even extraction. Afterwards, the piston is returned to its original position to increase the brewing chamber volume.

[0085] The brewing chamber 12 is then enlarged to allow water to be introduced, so that there is enough space for the coffee grounds to swell upon contact with the water. This is in Fig. 2d and 2e recognizable.

[0086] In a fifth step, hot water is supplied at an initial flow rate. This is subsequently referred to as the first brewing phase, e.g., a pre-brewing phase. During this phase, the brewing chamber is partially and rapidly filled. To ensure a phase transition of the flavor compounds, a certain holding time can optionally be provided. Preferably, the flow rate during pre-brewing is between 9 and 12 ml / s. After the rapid supply in the pre-brewing phase, a holding time can be provided in which the flow rate is reduced, but the brewing valve(s) remain open. This holding time can preferably be at least 3 seconds.

[0087] In a sixth step, hot water is then added again in a second brewing phase at a second flow rate. This can, for example, be the main brewing phase. Hot water is added slowly, preferably at a flow rate of less than 5 ml / s, and particularly preferably less than 3 ml / s. Uniform extraction is achieved through the slow flow rate, which also carries away soluble substances.

[0088] At the end of the sixth step, the transfer of most of the flavorings into the water is complete. The duration of the brewing phase can be controlled depending on the time, the amount (volume or mass of the water added), the pressure, and / or, particularly preferably, the conductivity.

[0089] Finally, in a seventh step, the flow rate is increased again, e.g., to 5-10 ml / s. The terms flow rate and throughput rate are to be understood synonymously in the context of this application. This third flow rate corresponds to the third brewing phase, which can be the so-called post-brew phase. This phase is preferred in order to obtain a balanced extraction result.

[0090] Finally, in an eighth step, the coffee grounds are ejected from the brewing chamber.

[0091] During the individual brewing phases, the brewing chamber can remain open on the outflow side, so that the coffee is dispensed into a coffee cup after each phase, i.e., during preparation.

[0092] The coffee in the brewing chamber can be dispensed as needed by closing the piston.

[0093] The pressure of 4 bar, or in particular 2.5 bar, is preferably not exceeded during coffee preparation over any of the brewing phases. Rather, the coffee preparation can particularly preferably take place without additional pressure from the piston 11 during the brewing phases.

[0094] The phase transition between the different brewing phases can occur depending on the following physical quantities and can vary depending on both the amount of coffee grounds and the total amount of water: a) Time-controlled based on a data set value or by a preset after a time x [s] has elapsed. This variant varies particularly with the amount of coffee, the water volume, and / or the desired coffee volume. b) Quantity-controlled based on a data set value or by a preset after / at a quantity x [ml]. c) Conductivity-controlled based on a data set value or by a preset after a certain percentage of measured conductivities of substances during the brewing process falls below a certain threshold [mS / cm]. In this variant, it is particularly possible to determine when the proportion of conductive substances has been largely extracted.

[0095] The flow rate of warm or hot water during the respective brewing phases can be regulated or controlled and can vary depending on both the amount of coffee grounds and the total amount of water.

[0096] The coffee is preferably prepared "cup by cup", but storage, for example in an internal warmer of the fully automatic coffee machine before dispensing is conceivable.

[0097] The inclusion of large particles (colloquially, crumbs) from the coffee grounds in the beverage is preferably prevented by using the filter. The brewing chamber volume can be variably changed, preferably automatically before brewing, and adjusted to the desired output volume of coffee.

[0098] The brewing pressure can preferably be determined before and / or after the brewing chamber 12 for the purpose of data collection.

[0099] The following is a specific preparation sequence as one possible execution variant. Brewing phases

[0100] I. 0-8 s [80ml] Brewing II. 8-40 s [70ml] Broths III. 40-70 s [150ml] Re-brewing parameter

[0101] Crowd: 300 ml Duration: 70 s Weight: 10 g Conductivity: 2,45 mS / cm (Ø) Brewing pressure: 0,5 bear Brewing temperature: 92 °C

[0102] Under these conditions, the measurement diagrams of the Fig. 3 created. In the brewing phase I, a pressure increase can be observed due to the rapid supply of water, whereby a small pressure can be built up by the piston 11.

[0103] During the main brewing phase II, the increase in conductivity can be recognized ( Fig. 3b ) that a large proportion of the ingredients pass through during this phase. The flow rate ( Fig. 3c ) is significantly lower than in the initial brewing phase I. As can be seen from the pressure curve, the main brewing phase takes place without a significant pressure build-up ( Fig. 3a ).

[0104] This pressure increases again during the third post-brewing phase. The flow rate is also increased. The conductivity is low compared to the main brewing phase and continues to decrease steadily.

[0105] In Fig. 4A first variant is shown, in which a brewing process proceeds in three different brewing phases I, II, and III. The volumetric flow rates Qbrew a, b, and c, and thus also the first, second, and third flow rates, vary depending on the brewing phase. The extraction of flavor compounds can be traced based on the conductivity. It can be seen that, particularly in the third brewing phase III, only a few flavor compounds are extracted.

[0106] Preferred flow rates or volume flows for the individual brewing phases of the Fig. 4 However, the following also apply to other procedural variants: First flow rate: Q broths a: 2-5 ml / s Second flow rate: Q broths b: 5-10 ml / s Third flow rate: Q broths c: 10-15 ml / s

[0107] Fig 5Figure 1 shows an alternative second variant of a method according to the invention in which two brewing phases I and II with identical volume flows Q Brew a are passed through the brewing chamber and in which a third brewing phase III with a different volume flow Q Brew c is operated simultaneously with a volume flow of hot water via a bypass line Q Bypass a. In this third brewing phase III, in addition to residual extraction, possibly also of some bitter substances, the aim is in particular to achieve a desired volume of coffee.

[0108] How based Fig. 5 As can be seen, the inventive method does not necessarily have to include three brewing phases with three different volume flows or flow rates; however, it is possible to do so and thereby achieve a more balanced taste.

[0109] The bypass volume flow Q Bypass b can be switched on, for example, in the second brewing phase II or at the end of the brewing process after completion of the third brewing phase III. Reference sign

[0110] 1 Fully automatic coffee machine 2 Brewing unit 3 Hot water boiler 4 Water inlet 5 Water pump 6 Measuring device for flow rate determination 7 Non-return valve 8 Flow limiter 8a-8c Brewing valves 9 Sensor 10 Dispensing unit 11 Piston 12 Brewing chamber 13 Control and / or evaluation unit 14 Slide valve 15 Filter 16 Control elements 16a-16b Bypass valves 17 Bypass Fig. 3a Pressure measurement over the brewing process Fig. 3b Conductivity diagram over the brewing process Fig. 3c Flow measurement over the brewing process IFirst brewing phase IISecond brewing phase IIIThird brewing phase

Claims

1. Method for making a coffee beverage with a filter-coffee taste by means of a fully automatic coffee machine (1), wherein the fully automatic coffee machine (1) has at least one brewing unit (2) with a brewing chamber and has a plunger (11) which is movable, in particular linearly displaceable, in the brewing chamber for setting a brewing chamber volume, wherein the method, with at least the following steps of: a. filling the brewing chamber (12) with ground coffee; and b. feeding water into the brewing chamber (12) for the purpose of extraction in the course of a brewing process, wherein at least the plunger (11) is arranged during at least one brewing phase of the brewing process in a position in which the brewing chamber volume is greater than the volume of the ground coffee in a loosely filled state in the brewing chamber (12) after the filling according to step a has taken place, wherein the brewing process comprises a number of brewing phases (I, II, III) in which water in each case is made to pass through the ground coffee with different flow rates relative to the brewing phases (I, II, III) and wherein the change between the brewing phases (I, II, III) is performed by measuring instruments detecting and / or determining a physical variable, in particular conductivity, the refractive index and / or the amount and / or volume of ground coffee and / or water supplied and / or the amount of coffee removed, characterized in that the fully automatic coffee machine has a bypass line starting from a hot water boiler to a dispensing unit (19) with one or more control elements, wherein a dispensing of hot water takes place, preferably simultaneously with the brewing process and / or the dispensing of coffee from the brewing unit, to achieve a predetermined coffee volume.

2. Method according to claim 1, characterized in that a change of the brewing phases (I, II, III) is adjusted by detecting a supplied amount of water by taking into account the supplied amount of ground coffee.

3. Method according to claim 1 or 2, characterized in that a change of the brewing phases (I, II, III) is performed by detecting measured values by a measuring sensor (9), wherein a measuring sensor (9) for detection is arranged downstream or preferably upstream of the brewing unit (2) in terms of flow.

4. Method according to one of the preceding claims, characterized in that the water flows through the ground coffee during the at least one brewing phase without exerting a mechanical contact pressure on the ground coffee that is further compressive compared to the loosely filled state.

5. Method according to one of the preceding claims, characterized in that the ground coffee is substantially present in an uncompacted manner in the loosely filled state at the start of step b.

6. Method according to one of the preceding claims, characterized in that the brewing chamber volume at the beginning of step b is at least 50% larger, preferably at least twice as large, as the volume of the ground coffee in the loosely filled state.

7. Method according to one of the preceding claims, characterized in that the brewing chamber is constructed in such a way that at the beginning of step b only the ground coffee is arranged inside the brewing chamber.

8. Method according to one of the preceding claims, characterized in that the brewing process comprises a first brewing phase (I) with a first flow rate and a second brewing phase (II) with a second flow rate and preferably a third brewing phase (III) with a third flow rate, wherein the second flow rate is smaller than the first and / or the third flow rate.

9. Method according to one of the preceding claims, characterized in that the fully automatic coffee machine (1) comprises a coffee grinder, wherein the method comprises grinding coffee beans to a predefined size for filter coffee.

10. Method according to one of the preceding claims, characterized in that the plunger (11) performs, prior to step b, a shaping of the bulk of the ground coffee without substantial compression of the bulk of the ground coffee, so that the volume of the brewing chamber (12) is reduced during the shaping process.

11. Method according to claim 10, characterized in that prior to the brewing process, the plunger (11) is returned to the first position so that the volume of the brewing chamber (12) expands again, preferably by at least 100% compared to the volume in the shaped state.

12. Method according to one of the preceding claims, characterized in that the plunger (11) remains in the first position during the entire brewing process.

13. Method according to one of the preceding claims, characterized in that the plunger (11) can be adjusted to a second position in which it rests on the ground coffee along an end face, preferably over the entire surface, without exerting a contact pressure on the ground coffee, in particular during the shaping process.

14. Method according to one of the preceding claims, characterized in that the plunger (11), in the first position, is present in the maximally extended position, limited by the structural design of the brewing unit (2).

15. Method according to one of the preceding claims, characterized in that the fully automatic coffee machine (1) has a filter (15), in particular a CIP-capable permanent filter, in particular as part of the brewing unit (2).

16. Method according to one of the preceding claims, characterized in that the brewing pressure during the brewing process is less than 4 bar, preferably less than 2.5 bar.

17. Method according to one of the preceding claims, characterized in that the brewing chamber (12) is closed during the brewing process except for an inlet for hot water and / or an outlet for coffee.

18. Method according to one of the preceding claims, characterized in that a stepwise adjustment of the flow rate is performed during the brewing process to alternate between two brewing phases.

19. Fully automatic coffee machine (1) comprising at least one brewing unit (2) with a linearly displaceable plunger (11) for setting a volume of a brewing chamber (12) of the brewing unit (2) and a control and / or evaluation unit (13) which is set up to carry out a method according to one of the preceding claims.