DE102019206397B3 - Method for the time-saving control of a coffee machine - Google Patents

Abstract

The invention relates to a method for controlling a coffee machine with a continuous flow heater as the heating element (4), comprising the steps: - selection of a coffee beverage type (K), - preparation of the coffee powder for preparing a coffee beverage based on the selection of the coffee beverage type (K), while simultaneously Water in the coffee machine is heated to a target temperature predetermined by the selection, - preparation of a coffee drink based on the selection of the coffee drink type (K). The invention also relates to a corresponding coffee machine.

Description

The invention relates to a method for controlling a coffee machine and a coffee machine controlled in this way.

The DE 10 2010 039 840 A1 describes a water heater with a heating device, a flow tube coupled to it, which comprises an inlet area, a central area and an outlet area, at least one first temperature sensor in the inlet area of the flow tube, a pump device and a control device that is coupled to the heating device, the pump device and the first temperature sensor is. The control device is designed to determine the following values before the start of a heating process: a first temperature value in the inlet area when the pump device and heating device are switched off and a second temperature value in the inlet area when the pump device and the heating device are in operation in a first predeterminable power level, with the Dependence of at least one setpoint temperature of the fluid at the outlet of the flow tube on at least the first temperature value, the second temperature value, the first predeterminable power level of the pumping device and different heating values correlated with power levels of the heating device is stored, the control device also being designed to control the heating device in this way that this is operated with a power level that, according to the stored dependency, at a set power level of the pump device to the target temperature of the F. luids at the outlet of the flow tube.

The pamphlet U.S. 5,307,733 A describes a method for controlling a coffee machine with a flow heater as the heating element, in which the heating element begins to heat during the preparation of the coffee powder.

The invention is based on the object of specifying an improved method and an improved coffee machine and, in particular, of achieving a clearly defined state at the start of beverage preparation.

The invention solves this problem by means of the subjects of the independent claims. The subclaims reproduce preferred embodiments.

At the beginning of the preparation of a coffee drink, a coffee machine must be put into a state in which coffee can be prepared. For example, water must first be present in a storage tank or provided through a fixed water connection and the water must be heated to the desired temperature.

Known coffee machines have hitherto had no possibility of detecting the current system status at the start of coffee preparation and are therefore in an undefined status from the point of view of process engineering at this point in time.

The method according to the invention is used to control a coffee machine. The invention is directed to coffee machines that include a heating element for heating water, in particular a flow heater. The invention is particularly preferably directed to fully automatic coffee machines with a grinder so that a selected coffee beverage can be prepared from freshly ground coffee powder. The procedure consists of the following steps:

- Selection of a type of coffee beverage

A user selects a type of coffee beverage in a manner known per se. For this purpose, it is assumed that the coffee machine is designed to dispense a large number of different types of coffee beverages. A preferred example is a fully automatic coffee machine with options for different types of coffee beverages. “Type of coffee beverage” is understood to mean a type of coffee beverage which differs from other beverages on the basis of at least one parameter. Difference parameters are not limited to the type of coffee (espresso, cappuccino, cafe crema, etc.) alone, but can also affect the size of the beverage (small, medium, large) or other parameters, such as B. the beverage strength, temperature, the milk content or the type of crema. From the selection, e.g. the type of coffee powder to be ground, the amount of ground coffee powder or the degree of grinding, as well as the brewing temperature, the amount of water or corresponding parameters depend.

- Preparation of the coffee powder

The coffee powder is prepared based on the selection of the coffee beverage type. This may include grinding the coffee powder, but in any case filling it or determining the quantity of it, placing it in a brewing unit and pressing it there. The preparation preferably comprises grinding the coffee in portions, measuring the amount of (possibly ground) coffee powder, introducing the coffee powder into a brewing unit and pressing the coffee powder in the brewing unit.

According to the invention, the water in the coffee machine is simultaneously with the preparation of the coffee powder on one by the selection heated predetermined target temperature, the amount of energy (Q) is calculated before the water is heated, which is required to heat the water to the target temperature (T _z ), and a heating element of the coffee machine based on the calculated amount of energy (Q) to heat the Water is controlled and / or regulated. As a result, the time to prepare the coffee powder is used optimally and hot water is available shortly afterwards and does not have to be heated up first. The target temperature is preferably that temperature which is required for the brewing step which follows or follows after the preparation of the coffee powder. In a two-stage brewing process, the target temperature can be a main brewing temperature or at least a pre-brewing temperature. However, the target temperature can also be a different temperature than the brewing temperature, especially if the time to prepare the coffee powder is too short to heat the water to the brewing temperature. If the target temperature is not the brewing temperature, the target temperature can be the temperature value that can be reached during preparation. Then, after preparing the coffee powder, you can plan an additional time to heat the water to the brewing temperature. In practice, this step usually takes place within the first 15 s of coffee preparation and can shorten the entire preparation process by approx. 8 s or more.

- Making a coffee drink based on the type of coffee drink selected. This step is well known. In contrast to the prior art, however, brewing can now be started immediately after the preparation of the coffee powder, since no additional time has to pass for the water to be heated. This is because the water can be heated to the target temperature, for example, during the grinding process.

According to a preferred embodiment, the time required to prepare the coffee powder is determined, and also the time required to heat the water to the target temperature. Taking advantage of these times, a heating element of the coffee machine, in particular a flow heater, is then controlled to heat the water so that the target temperature of the water is later than 1 s before the preparation of the coffee powder and / or less than 5 s, preferably less than 1 s after the preparation of the coffee powder is finished. This has the advantage that the target temperature of the water can not only be set during preparation, but also that this target temperature is available on time for preparation, namely neither too early nor too late. The filling level of the heating element, namely the flow heater, is preferably also measured and taken into account when determining the times. For this purpose, the heating element is particularly preferably filled with a certain amount of water before it is heated, at least when the fill level is too low.

Determining the time required to prepare the coffee powder depends, among other things, on on the previous selection of the type of coffee beverage. For example, it can be stored together with the coffee beverage type in question in a memory unit of the coffee machine and thus be available for the method. However, it can also be calculated individually, which is described in more detail below in the context of a preferred embodiment.

The time it takes to heat the water to the target temperature can be calculated from parameters available to a typical coffee machine or from additional measurements using sensors. If z. B. is known what temperature the water has, the time to heat the water can be calculated with the known heating power of the heating element.

For example, an evaluation of the temperature sensor values when the water enters can be used for such a calculation. Both the current temperature and a temperature drop as a result of the filling of the liquid system of the coffee machine with fresh water can be determined. Likewise, a temperature profile can be determined on the basis of the residual heating energy, the water tank temperature and / or the heating fill level, and this temperature profile can be used to determine when the target temperature will be reached. In describing a preferred embodiment, this point will be further elaborated.

According to a preferred embodiment, after the water has been heated, the liquid lines of the coffee machine leading to the brewing unit are preliminarily heated. This is preferably done in that heated water is passed through them. No water must get into the brewing unit if there is already coffee powder in it. The heated water can preferably be directed to a valve island in front of the brewing unit and drained from there, preferably through a line back to the heating element or to the storage tank so that the water can be heated again and does not have to be discarded. As a result, the preparation water no longer cools down during the following (pre) brewing process due to cold pipes. The preparatory heating of the liquid lines is preferably completed earlier than 1 s after the preparation of the coffee powder for preparation has ended.

According to the invention, before the water is heated, the amount of energy Q calculated, which is required to heat the water to the target temperature. A heating element of the coffee machine is then used to heat the water based on the calculated amount of energy Q controlled and / or regulated. The amount of energy Q can, for example, with a known amount of water with the mass mw and the specific heat capacity cw of 4190 J / (kgK) and a known mass m _{H of} the heating element and its specific heat capacity c _H (for aluminum e.g. approx. 900 J / ( kg K)) with the target temperature T _Z and the current temperatures of the water T _W and the heating element T _H can be calculated as follows: $$\text{Q}\left({\text{T}}_{\text{W.}},{\text{T}}_{\text{H}}\right)={\text{m}}_{\text{H}}{\text{c}}_{\text{H}}\left({\text{T}}_{\text{Z}}-{\text{T}}_{\text{H}}\right)+{\text{m}}_{\text{W.}}{\text{c}}_{\text{W.}}\left({\text{T}}_{\text{Z}}-{\text{T}}_{\text{W.}}\right)$$

To determine the current temperatures of the water Tw and the heating element T _H and thus the energetic starting situation of the coffee machine, sensor values can be used. Alternatively, the temperature of the heater can be adjusted by a rinsing process of the water, whereby T _H = T _W applies. In this case, the temperature of the system usually drops at the beginning, since the water in the storage tank is usually colder than the determined temperature of the water in the rest of the system. It is generally advantageous to measure the temperature of the water in the water tank or to estimate the amount of energy required Q to be able to calculate exactly.

It can be advantageous to use sensors and other measuring units to first determine process-related or procedural target variables, e.g. B. the above temperatures. Other values can be derived from the selection made, for example the target temperature of the brewing process (pre-brewing process or main brewing process), the target quantity, the target flow rate of the brewing process or the step response on the heater, i.e. the real temperature profile after a sudden increase in heating output. On the basis of the target temperature it can then be decided at the same time whether and to what extent the state of the system is changed, e.g. B. by heating up, cooling down or by heating the system with simultaneous water supply. This can already be derived from formula (1), where a negative amount of energy would mean cooling.

For example, the method can be carried out as follows. First, a type of coffee beverage is selected by a user on a selection unit of the coffee machine. This means that parameters such as the type of drink, the amount of coffee powder, the compression pressure of the powder in the brewing unit, the amount of water and / or the target temperature are already specified.

As a preparatory step, sensors measure the current temperature of the water in the coffee machine's preparation system, for example based on previous preparation processes, and possibly also the temperature of the water in the tank. The latter can alternatively be estimated at 20 ° C room temperature.

The heating level can also be estimated or calculated. This can e.g. by means of a temperature sensor and a measurement of a temperature curve over time within a heating period. A function of the temperature over time, in particular a time derivative of this function, allows an estimate of the fill level of the heater. Is e.g. If a temperature sensor is connected downstream of the heater, it is easy to estimate by looking at the temperature curve whether the temperature sensor is in contact with water or not, i.e. the level of the heater is above or below the temperature sensor. If the temperature curve is comparatively steep (and possibly also linear), the temperature sensor experiences good heat conduction through the water, so the water level reaches at least as far as the temperature sensor. If the curve is flatter or if the heat reaches the temperature sensor later, the water level is below the temperature sensor. The use of several temperature sensors and an evaluation of their data can provide more precise results.

In the next step, the amount of energy required is derived from a set of the aforementioned values Q determined for reaching the operating state or the target temperature. According to a predetermined formula or table, the time that is required to heat the water to the target temperature is preferably calculated from the amount of water to be heated, the output of the heating element, the prevailing temperature and the target temperature.

The grinder is now started to prepare the coffee powder. The time it takes to grind the required amount of coffee, pour it into the brewing unit and press it there is known. For example, if it is three seconds longer than the time to heat the water, the heating element is z. B. switched on three seconds after starting the grinder and heated the water while preparing the coffee powder. Alternatively, the heating element can be started at the same time as the grinder and the remaining three seconds can be used to heat the lines up to the brewing unit. In the event that it takes longer to warm the water to the brewing temperature than it does to prepare the coffee, a lower temperature than the brewing temperature can be aimed for as the target temperature. The process would still save time, as the water no longer has to be heated from a cold state to the brewing temperature.

A coffee machine grinder can take a long time to grind a given amount of coffee if the heating element is in operation at the same time. This can be due to a limited output of the power supply unit of the drinks machine. With the known amount of energy (see above), it can be extrapolated how long the heating element has to run with what power in order for the water to reach the target temperature. This can be used to determine how much longer the grinder will run. This can be used to determine the time it takes to prepare the coffee powder with the extension of the grinding process, and with the known time to heat the water to the target temperature, optimal time management can be achieved.

• - eine Auswahleinheit ausgelegt zur benutzerseitigen Auswahl und Angabe eines Kaffeegetränketyps;
• - einen Durchlauferhitzer als ein Heizelement;
• - eine Steuereinrichtung zur
  1. a) Steuerung einer Vorbereitung des Kaffeepulvers zur Zubereitung eines Kaffeegetränks basierend auf der Auswahl des Kaffeegetränketyps,
  2. b) Steuerung des Aufheizens von Wasser im Kaffeeautomaten auf eine durch die Auswahl vorbestimmte Zieltemperatur während der Vorbereitung des Kaffeepulvers,

wobei eine Recheneinheit (9)-dazu ausgelegt ist, vor dem Aufheizen des Wassers die Energiemenge zu berechnen, die benötigt wird, um das Wasser auf eine Zieltemperatur (T_z ) aufzuheizen, und das Heizelement des Kaffeeautomaten zum Aufheizen des Wassers basierend auf der berechneten Energiemenge (Q) zu steuern und/oder zu regeln.A coffee machine according to the invention comprises the following components:

• - A selection unit designed for the user to select and specify a type of coffee beverage;
• - a water heater as a heating element;
• - A control device for
  1. a) control of a preparation of the coffee powder for the preparation of a coffee beverage based on the selection of the coffee beverage type,
  2. b) Control of the heating of water in the coffee machine to a target temperature predetermined by the selection during the preparation of the coffee powder,

A computing unit (9) is designed to calculate the amount of energy required to bring the water to a target temperature ( T _z ), and the heating element of the coffee machine to heat the water based on the calculated amount of energy ( Q ) to control and / or regulate.

According to the invention, such a coffee machine can be designed to carry out the method according to the invention.

According to the invention, the coffee machine comprises a computing unit, for. B. a processor that is designed to measure the amount of energy before the water is heated Q to calculate that is needed to heat the water to the target temperature and a heating element of the coffee machine to heat the water based on the calculated amount of energy Q to control and / or regulate.

According to a preferred embodiment, the coffee machine comprises a computing unit (possibly the same as the above), which is designed to calculate the time it takes to prepare the coffee powder and the time it takes for the water to heat up to the target temperature and then to control a heating element of the coffee machine to heat the water. The control is preferably carried out in such a way that the target temperature of the water is reached later than 1s before the end of the preparation of the coffee powder and / or less than 1s after the end of the preparation of the coffee powder. The coffee machine preferably also includes a measuring unit for measuring the fill level of the heating element.

The advantage of the invention is that with the system start according to the invention, the coffee machine, preferably the fully automatic coffee machine, is brought to the operating temperature or target temperature during a preparation process, which preferably also includes a grinding process. This happens almost imperceptibly to the user. In addition, the coffee machine is no longer in an undefined state. This leads to a stabilized preparation process and a significant reduction in the volume spread in a series of coffee beverages. Furthermore, the cup temperature, in particular of the first cup of a preparation series, can be significantly improved.

In addition, the preparation water comes into contact with the coffee powder at a defined temperature ("first contact temperature"). This leads to a constant coffee quality and is used for improved taste profiling in a fully automatic coffee machine.

• 1: ein schematisches Beispiel für einen Kaffeeautomaten,
• 2: ein Blockschaltbild zum Ablauf eines erfindungsgemäßen Verfahrens,
• 3: ein Beispiel für einen Verlauf einiger Parameterwerte während der Zubereitung eines Kaffeegetränks.

The principle of the invention is explained in more detail below with reference to a drawing by way of example. In the drawing show:

• 1 : a schematic example of a coffee machine,
• 2 : a block diagram for the sequence of a method according to the invention,
• 3 : an example of a course of some parameter values during the preparation of a coffee beverage.

• - eine Brüheinheit 2, die mit einem Mahlwerk 2a gekoppelt ist, wobei das Kaffeepulver aus dem Mahlwerk 2a in der Brüheinheit 2 verpresst wird,
• - eine Pumpe 3, durch die Wasser aus einem Wassertank 5 durch einen Durchlauferhitzer als Heizelement 4 hindurch in die Brüheinheit 2 gepumpt wird,
• - eine Auswahleinheit 6 zur bedienerseitigen manuellen Auswahl und Angabe eines gewünschten Kaffeegetränketyps K,
• - eine Steuereinrichtung 7 ausgelegt zur Steuerung der Zubereitung eines Kaffeegetränks des ausgewählten Kaffeegetränketyps K durch den Kaffeeautomaten 1,
• - eine Recheneinheit 9 ausgelegt zur Berechnung von Steuerdaten für die Steuereinrichtung 7, und
• - eine Datenschnittstelle 8 zur Herstellung eines Datenkontakts mit der Auswahleinheit 6. Dadurch können Daten zur Auswahl des Kaffeegetränketyps K an die Recheneinheit 9 weitergegeben werden. Der Pfeil von der Auswahleinheit 6 zur Datenschnittstelle 8 soll dabei die Richtung des Datenflusses andeuten. Diese Datenschnittstelle 8 ist dabei auch zum Senden von Steuerdaten (s. zweiter Pfeil) an eine Steuereinrichtung 7 zur Steuerung einer Zubereitung eines Kaffeegetränks des ausgewählten Kaffeegetränketyps K durch den Kaffeeautomaten 1 ausgelegt.

1 shows a fully automatic coffee machine. In addition to other units required to prepare coffee, it includes the following components in particular:

• - a brewing unit 2 that with a grinder 2a is coupled, the coffee powder from the grinder 2a in the brewing unit 2 is pressed,
• - a pump 3 through the water from a water tank 5 by a water heater as a heating element 4th through into the brewing unit 2 is pumped,
• - a selection unit 6 for manual selection and specification of a desired type of coffee beverage by the operator K ,
• - a control device 7th designed to control the preparation of a coffee beverage of the selected coffee beverage type K through the coffee machine 1 ,
• - an arithmetic unit 9 designed to calculate control data for the control device 7th , and
• - a data interface 8th to establish data contact with the selection unit 6 . This allows data to be used to select the type of coffee beverage K to the computing unit 9 be passed on. The arrow from the selection unit 6 to the data interface 8th should indicate the direction of the data flow. This data interface 8th is also used to send control data (see second arrow) to a control device 7th for controlling a preparation of a coffee beverage of the selected coffee beverage type K through the coffee machine 1 designed.

To prepare a coffee drink, water is drawn from the water tank 5 by means of the pump 3 through the heating element 4th pumped, there to the target temperature T _Z warms up and enters the brewing unit when it is hot 2 , in which there is coffee powder, which is produced by the grinder 2a was ground. This process is carried out by means of the computing unit 9 via the data interface 8th controlled in the manner described below.

2 shows a block diagram for the sequence of a method according to the invention for controlling the coffee machine 1 ( 1 ).

In step I, the user selects a type of coffee beverage K , e.g. B. using selection buttons on the coffee machine 1 . It sets the starting point of the method according to the invention.

The amount of energy is calculated in step II Q , which is needed to heat the water to the target temperature. This can be based on sensor data or empirical values based on the selection of the type of coffee beverage K happen.

In step III is the time t _K determined, which is required to prepare the coffee powder, and determines the time tw that is required to heat the water to the target temperature. This can e.g. B. based on the previously calculated amount of energy Q and the parameters known from the beverage selection (e.g. amount of water, target temperature T _z ) as well as measured values for the current temperature.

In step IV, the coffee powder is used to prepare a coffee beverage based on the selection of the coffee beverage type K prepared (step IVa). While this is happening, water will be in the coffee machine 1 to a target temperature predetermined by the selection T _Z heated (step IVb).

Simultaneously with the preparation in step IVa, lines of the coffee machine leading to the brewing unit are preliminarily heated in step IVc in that heated water is passed through them. In 1 The line between the heating element stands almost symbolically for this 4th and the brewing unit 2 .

In step V, the coffee beverage of the selected coffee beverage type is prepared K through the coffee machine 1 . This can take place immediately, since the preparation water is already available at the ready-made temperature.

3 shows a course of some parameter values during the preparation of the coffee beverage. The solid line represents a temperature curve T of water, the dashed line is the power curve of the heating element 4th ( 1 ) and the dash-dotted curve the power curve of the grinder 2a . In the area of a temperature sensor in the device, the water still has a certain initial temperature from a previous preparation process. The temperature T then sinks because cold water from the water tank 5 is pumped in. While the grinder 2a runs, the water is heated according to the invention. This happens slowly, as cold water is always fed in, which has to be heated up. The heating element 4th however, it also stores part of the thermal energy. As soon as there is no more water from the water tank 5 is pumped up, the temperature of the now resting water rises more sharply during the grinding process, as it removes the residual heat from the heating element 4th records. Because the above formula (1) provides the necessary amount of energy Q results and also the amount of energy of the heating element 4th taken into account, this temperature curve T calculated in advance so that the correct temperature is available at the end of the grinding process. The further course of the temperature curve T corresponds to that of a typical brewing process.

Since the embodiment described in detail above is an example, it can be modified in the usual way by the person skilled in the art to a wide extent without departing from the scope of the invention. In particular, the specific embodiments of the invention, the method and / or the coffee machine can also take place in a form other than that described here. In particular, the fluid system can also be designed in a different form, for example with a return line for returning the water to the heating element or the storage tank after the supply lines have been preheated. Furthermore, the use of the indefinite article “a” or “an” does not exclude the possibility that the relevant characteristics can be present several times or more than once.

List of reference symbols

1

Coffee machine

2

Brewing unit

2a

Grinder

3

pump

4th

Heating element

5

Water tank

6th

Selection unit

7th

Control device

8th

Data interface

9

Arithmetic unit

H

Heating element performance curve

K

Coffee beverage type

M.

Grinder performance curve

Q

Amount of energy

T

Temperature curve

Item

Target temperature

t _K , t _W

time

Claims (8)

A method for controlling a coffee machine (1) with a flow heater as a heating element (4), comprising the steps: - selection of a coffee beverage type (K), - preparing the coffee powder for preparing a coffee beverage based on the selection of the coffee beverage type (K) while simultaneously water in the coffee machine (1) is heated to a target temperature (Tz) predetermined by the selection, - preparation of a coffee beverage based on the selection of the coffee beverage type (K), characterized in that the amount of energy (Q) is calculated before the water is heated is required to heat the water to the target temperature (Tz), and a heating element (4) of the coffee machine (1) is controlled and / or regulated based on the calculated amount of energy (Q) for heating the water. Procedure according to Claim 1 , characterized in that the preparation of the coffee powder comprises at least the filling and preferably additionally the pressing of the coffee powder in a brewing unit (2) of the coffee machine (1) and / or additionally the grinding of the coffee powder. Method according to one of the preceding claims, characterized in that - the time (t _K ) is determined which is required to prepare the coffee powder and - the time (t _W ) is determined which is required to heat the water to the target temperature (Tz) is required and a heating element (4) of the coffee machine (1) for heating the water is controlled so that the target temperature (T _Z ) of the water a) later than 1 s before the preparation of the coffee powder and / or b) less than 1 s is reached after the preparation of the coffee powder has ended, the filling level of the heating element (4) preferably also being measured and taken into account when determining the times. Method according to one of the preceding claims, characterized in that after the water has been heated up, the liquid lines of the coffee machine (1) leading to the brewing unit (2) are preliminarily heated, preferably in that heated water is passed through them, the preliminary heating of the liquid lines preferably earlier than 1 s after completing the preparation of the coffee powder for preparation. Coffee machine (1), comprising: - a selection unit (6) designed to select a type of coffee beverage (K), - a flow heater as a heating element (4), - a control device (7) designed to a) control a preparation of the coffee powder for the preparation of a coffee beverage based on the selection of the coffee beverage type (K), b) control of the heating of water in the coffee machine (1) to a target temperature T _Z predetermined by the selection during the preparation of the coffee powder, characterized by a computing unit (9) which is designed to Before heating the water, calculate the amount of energy (Q) that is required to heat the water to the target temperature (T _Z ) and the heating element (4) of the coffee machine (1) to heat the water based on the calculated amount of energy ( Q) to control and / or regulate. Coffee machine (1) Claim 5 , characterized by a computing unit (9) which is designed to calculate the time that is required to prepare the coffee powder, as well as to calculate the time that the water will need to heat up to the target temperature (Tz), and then a The heating element (4) of the coffee machine (1) for heating the water should preferably be controlled in such a way that the target temperature (Tz) of the water is reached later than 1 s before the preparation of the coffee powder and / or less than 1 s after the preparation of the coffee powder is finished is, the coffee machine preferably also has a measuring unit for measuring the fill level of the heating element (4). Coffee machine (1), characterized in that it is used to carry out a method according to one of the Claims 1 to 4th is designed. Coffee machine (1), characterized in that it is a fully automatic coffee machine according to one of the Claims 5 or 6 is equipped with a grinder (2a) for the production of coffee powder.

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