METHOD AND DEVICE FOR DESCALING A HOT DRINK MAKER

Description

[0001] The present invention relates to a method and a device for descaling a hot beverage device. The hot beverage device comprises an electric instantaneous water heater, a temperature sensor, a signal generator, and a control or regulating arrangement.

[0002] Hot beverage devices with a temperature sensor are known, for example, from WO 2014 / 170208 A1 and US 2017 / 273502 A1.

[0003] DE 10 2010 002 438 A1 concerns a hot beverage device for detecting calcification with two temperature sensors.

[0004] The object of the present invention is to optimize known descaling processes and to determine the effectiveness of a descaling process.

[0005] The object is achieved according to the invention in the method mentioned at the outset, which is based on a hot drinks device with a temperature sensor at the outlet of the instantaneous water heater, the output sensor, in that in a first step a) a descaling process is started, in a second step b) a cyclical flow of descaling agent is generated and a heating output is cyclically introduced, then during each cycle in a step c) at least one value is determined at the output sensor, the determined value or a comparison value determined from several values ​​of the output sensor or a controlled variable of the control arrangement is compared in a step d) with a limit value stored on the device and in a last step e) the cycles are repeated until the limit value is at least reached, whereupon a first signal is output that the descaling process has been successfully completed.

[0006] The process therefore involves at least five steps. In the first step a), the descaling process is started by the user or automatically. For the descaling process, a descaling agent is added to the hot drinks machine. The descaling agent can be a solution of water and a solid descaler, for example descaling powder or descaling tablets, or a ready-made descaling solution that can be added to the hot drinks machine, stored there, or prepared in the hot drinks machine. Machine-side preparation of descaling agent often takes place in hot drinks machines that can be built into kitchen units. There, the ready-made descaling agent or its ingredients can be stored in sufficient quantities for several descaling processes. In the case of portable hot drinks machines orIn so-called stand-alone devices, however, the descaling agent is usually added only when needed, immediately before the descaling process is carried out. The descaling process according to the invention can be used with both types of hot beverage machines.

[0007] During the descaling process, a cyclic flow of descaling agent is generated in step b). This occurs with the cyclically repeated pulse peaks typical of instantaneous water heater operation. Between the pulse peaks, the fluid flow is not zero, but merely significantly lower, so that descaling agent continues to flow through the instantaneous water heater.

[0008] The descaling agent is more effective and removes the limescale layer faster when heated. Therefore, in step b), the descaling agent is heated in the instantaneous water heater by cyclical application of heat. Heat is the amount of heat energy applied at a defined time interval. Its peak power generally remains the same from cycle to cycle. During the process, the duration of the applied heat can remain constant or be varied.

[0009] After each pulse peak of the fluid flow, the instantaneous water heater is switched on and the heat energy is introduced into the descaling agent in pulses. After a predetermined period of time, the instantaneous water heater is switched off again. The temperature of the descaling agent, which can be detected at the output sensor, initially rises due to the inertia of the instantaneous water heater, but then cools again because there is a constant fluid flow in the instantaneous water heater. The temperature curve of the descaling agent thus follows a largely sinusoidal shape throughout the entire descaling process. A cycle can be considered, for example, a time interval from the introduction of descaling agent with one pulse peak to the next pulse peak.

[0010] In the next step (c), a temperature value is determined at the output sensor during each cycle. This value increases as the limescale layer decreases during the descaling process, as the descaling agent absorbs more heat energy.

[0011] Subsequently, in step d), the recorded temperature value is compared with a limit value stored on the device. This limit value represents sufficient reduction of the limescale layer in the instantaneous water heater and is based on empirical values. If the limit value is reached or exceeded, the descaling process can be terminated or considered successful.

[0012] Alternatively, several values ​​from the output sensor can be recorded in step c) and a comparison value can be determined in step d). The comparison value can then be compared with the stored limit value. A difference or an average value can be calculated from the two recorded values ​​and compared with the stored limit value. Both average values ​​and the recorded values ​​from multiple cycles can be compared with each other and compared with a stored limit value. For this purpose, the stored limit value can be defined as a loss factor.

[0013] In another alternative, a controlled variable of the control system can be compared with a limit value stored on the device. This can be controlled by the control system depending on the temperature value detected at the output sensor. For example, the duration of the applied heating power or the duration of the fluid flow can serve as a controlled variable. In the first case, heating power can be saved; in the second case, the cycles can be shortened, thus accelerating the descaling process.

[0014] Steps b) to d) are repeated in step e) until the stored limit is reached or exceeded. The control or regulation system then completes or terminates the descaling process in step e) and issues a first signal indicating that the descaling process has been successfully completed.

[0015] During the descaling process, cold descaling agent is pumped into a flow heater of the hot beverage machine in pulses and repeating cycles, where it is heated. At the beginning of each cycle, the descaling agent is pumped into the flow heater in pulsed bursts. After a pulsed burst of a cycle, descaling agent continues to flow into the flow heater, but at a significantly lower flow rate. The descaling agent is heated by the pulsed introduction of heating power to the flow heater. For this purpose, the heater is switched on and off again after a defined time interval. During the cycle, at least one value is recorded at the output sensor by the control or regulating system for further evaluation.By comparing and evaluating the recorded value(s) with the limit value stored on the device, the control system can directly determine the progress of the descaling process. By directly determining the progress of the descaling process, the user receives quick feedback on whether the descaling process was sufficient.

[0016] In an advantageous embodiment, the limit value stored on the device can correspond to an absolute temperature value. During the descaling process, in step c), a temperature value is determined at the output sensor within each cycle. This value can advantageously be compared with the limit value of the same dimension. It corresponds to the temperature reached by the descaling agent at the end of the descaling process, when it can absorb the heating energy unhindered by a layer of limescale. At the beginning of the descaling process, the descaling agent absorbs the heating energy from the instantaneous water heater less effectively due to the insulating effect of the limescale layer. As the limescale layer decreases, the descaling agent absorbs the heat energy more effectively, and the temperature of the descaling agent at the output sensor increases while the duration of the applied heating power remains unchanged.This is a simple embodiment, since absolute values ​​of the second temperature sensor are compared with an absolute limit value and no control is necessary.

[0017] Alternatively, the control system can reduce the duration of the applied heating power during the descaling process. The reduction can be based on the value measured at the output sensor. If the value detected at the output sensor reaches a reference value, for example 60°C, the instantaneous water heater is switched off. Although the temperature at the output sensor initially rises due to the inertia of the instantaneous water heater, it soon drops when it is switched off. After a predetermined time, the control system switches the instantaneous water heater back on and the descaling agent is reheated. The limescale layer absorbs some of the energy from the instantaneous water heater and transfers it to the descaling agent after a time delay while the instantaneous water heater is switched off. The limescale layer slowly cools down again and can no longer transfer any energy to the descaling agent.The temperature of the descaling agent thus follows a damped oscillation. This means that the maximum temperatures recorded by the output sensor decrease as the limescale layer decreases, because the heating energy is absorbed more quickly by the descaling agent, and the minimum temperatures increase because the descaling agent cools less and less as the limescale layer decreases. Heating energy can be saved by regulating the heating cable based on its actual heating success at the output sensor.

[0018] In a further advantageous embodiment, the limit value stored on the device can correspond to a time value. The instantaneous water heater is switched on or off when the above-mentioned reference value of, for example, 60°C is reached at the output sensor. During the descaling process, the duration of the applied heating power can be reduced as the limescale layer decreases. The control system then records the duration of the applied heating power and subsequently compares the recorded value with the stored time value as the limit value. If the duration of the applied heating power reaches or falls below the stored time value, the descaling process can be considered successful.

[0019] In a further advantageous embodiment, the stored limit value can correspond to the difference between two temperature values. The difference can be calculated from two values ​​recorded by the output sensor. For this purpose, the control system records several values ​​from the output sensor within one cycle and calculates a difference value. Environmental influences and temperature fluctuations thus play a lesser role.

[0020] After the instantaneous water heater is switched on and off depending on the reference value of the output sensor, the temperature maxima decrease due to the removal of the limescale layer, while the temperature minima increase. The resulting curve of the output sensor values ​​is characteristic of a damped oscillation. In an advantageous embodiment of the above difference-based method, the control system can record a second value from the output sensor within the same cycle in a step i) after step c). A differential value is determined from the two recorded output sensor values, which decreases over time due to the damping of the sinusoidal oscillation. For this purpose, characteristic time intervals within a cycle are determined at the factory and stored in the control system. The differential value is compared with the limit value stored in the device, which corresponds to a differential value.If the limit value is reached, the control system issues the first signal via the electronics or the signal generator that the descaling process has been successfully completed.

[0021] In a further embodiment of the above difference-based method, logic can be stored in the control system that determines the maximum and minimum values ​​at the output sensor within a cycle. For this purpose, the temperature values ​​at the output sensor are continuously recorded. The control system determines these maximum and minimum values ​​and determines their difference, i.e., the maximum amplitude of each cycle. This amplitude decreases during the descaling process. It compares its value with the limit value stored on the device. When calculating the difference between the maximum and minimum values ​​of the second temperature sensor, defined ranges within a cycle are considered, and environmental influences are neglected. Thus, no intervals for recording the two values ​​for calculating the difference are stored in the control system.

[0022] In a further advantageous embodiment, the method according to the invention is based on a hot beverage device with an additional temperature sensor: On an outer, fluid-free surface of the instantaneous water heater or its housing, there is an input sensor, as also described in the above-mentioned DE 10 2010 002 438. The temperature values ​​of the input sensor represent the energy introduced into the instantaneous water heater. In a step ii) after step c), a temperature value can now be determined at the input sensor. The values ​​recorded by the two temperature sensors can be related to one another and compared with a limit value. The ratio describes a loss factor of the introduced heating energy, since the input sensor serves as a measure of the introduced energy and the output sensor as a measure of the heating energy arriving in the descaling agent.

[0023] In a further embodiment of the difference-based method, the control arrangement can, in a step iii) after step c), determine a difference value between the values ​​recorded by the two temperature sensors, the input and output sensors, in a cycle. It can then compare this difference with the limit value stored on the device, which corresponds to a difference. The input sensor represents the introduced heating energy, and the output sensor represents the energy arriving in the descaling agent. During the descaling process, the values ​​of the two temperature sensors can converge, possibly even to the same value. In this case, the limit value stored on the device can approach zero or become zero because the heating energy introduced into the instantaneous water heater has then been almost or completely absorbed by the water. In this embodiment, the hot beverage machine determines how much of the introduced heating energy reaches the descaling agent.

[0024] In a further embodiment, the descaling process can be aborted before the limit value is reached or because the limit value is not reached. A second signal can then be output that the descaling process could not be completed successfully. The second signal advantageously differs from the first signal from step e) because it signals a different device status. The aborting of the process can be due to a user-related fault, for example because too little water or descaling agent was added to a water container of the hot drinks machine or because the user removes a drip tray from the hot drinks machine into which used liquid is dispensed. The aborting of the process before the limit value is reached orHowever, failure to reach the limit may also be due to the fact that the descaling agent dosage was too low, for example, because the water hardness of the preparation water was not set correctly. In this case, the amount of descaling agent is insufficient to successfully descale the preparation device and must be refilled.

[0025] The second signal itself or another signal can, for example, indicate on a display the device-side requirement that led to the abort of the descaling process. This informs the user what they need to change so that the descaling process can be continued and completed successfully.

[0026] The above-mentioned object is also directed to the device mentioned at the outset, namely a hot beverage device with a continuous-flow heater, a number of temperature sensors, a signal generator, and a control or regulating arrangement. According to the invention, the above-mentioned object is achieved by precisely one temperature sensor located at the outlet of the continuous-flow heater. Surprisingly, the methods described above in claims 1 to 6 manage with only one temperature sensor located at the outlet of the continuous-flow heater. By eliminating the need for an additional temperature sensor, hot beverage devices can be manufactured more cost-effectively.

[0027] The principle of the invention is explained in more detail below using drawings. The drawings show: Figure 1 : a state-of-the-art design of a flow heater, Figure 2: a first concept of the process with an output sensor and Figure 3 : a second concept of the procedure.

[0028] Figure 1shows a schematic of a flow heater 1 of a hot beverage preparation device with an inlet 7 for fresh water and an outlet 2 for the heated water. An input sensor 3, hereinafter also referred to as the first temperature sensor, is attached to a surface of the flow heater 1 to determine its surface temperature. The surface temperature determined there serves as a measure of the applied heating power. The applied heating power is the heating energy applied in a defined time interval. An output sensor 4, hereinafter also referred to as the second temperature sensor, is attached to the outlet 2 downstream of the flow heater 1. It detects the temperature of the heated descaling agent. Both temperature sensors 3, 4 and an electronic unit or signal generator 5 are electrically connected to a control arrangement 6. The applied heating power is regulated by the control arrangement 6.This arrangement is used according to DE 10 2010 002 438 A1 to detect calcification, in particular of the instantaneous water heater 1.

[0029] According to the invention, it can also be used to assess the success of a descaling process: The goal of a descaling process is to break down a limescale layer in the instantaneous water heater 1. During a descaling process, cold water mixed with descaling agent is pumped into the instantaneous water heater 1 in pulses or in repeating cycles. In the repeating cycles, a fluid flow with pulse peaks and a heating power are introduced into the instantaneous water heater in pulses. Between the pulse peaks, the fluid flow does not become zero, but is significantly lower. The instantaneous water heater 1 heats the cold descaling agent that was pumped into it at the beginning of a first cycle. The next cycle starts with the next pulse peak of the descaling agent. During this time, the temperature at the first temperature sensor 3 rises.After a predetermined time interval, during which the descaling agent in the instantaneous water heater 1 has been fully heated, the supply of heating power is stopped. This causes the temperature at the first temperature sensor 3 to drop, especially since the heated descaling agent is expelled through the outlet 2 at the beginning of a second cycle by pumping in new, cold descaling agent. During a cycle, the temperature of the first temperature sensor 3 thus rises and falls, i.e., over several cycles, oscillations in the temperature behavior of the first temperature sensor 3 occur.

[0030] As soon as the heated descaling agent of the first cycle is displaced by further cold descaling agent through the outlet 2, the temperature of the second temperature sensor 4 rises. Once the heated descaling agent of the first cycle has been completely displaced and the instantaneous water heater 1 is filled with the descaling agent of the second cycle, the temperature at the second temperature sensor 4 drops. The second temperature sensor 4 also experiences a rise and fall in temperature within a cycle due to the pulsed introduction of the heating power and the fluid flow, although this occurs at a different time than the first temperature sensor 3. An oscillating behavior of the recorded temperature values ​​can therefore also be observed at the second temperature sensor 4.

[0031] Because the values ​​of the first temperature sensor 3 represent the heating energy used and the values ​​of the second temperature sensor 4 represent the effect of the heating energy used, the ratio of the values ​​of the first temperature sensor 3 and the second temperature sensor 4 allows conclusions to be drawn about the efficiency of the instantaneous water heater 1.

[0032] Viewed over time, the invention even allows descaling progress to be derived solely from the respective absolute values ​​of the first temperature sensor 3 and the second temperature sensor 4: The descaling agent, which is more effective in warm water, removes the limescale layer in the instantaneous water heater 1 during the descaling process. Since the limescale layer has a heat-insulating effect, thus hindering heat transfer from a heating element of the instantaneous water heater 1 to the descaling agent, the applied heating power reaches the descaling agent more quickly as the limescale layer decreases. This development can be understood by evaluating the measured values ​​of the first temperature sensor 3 and / or the second temperature sensor 4.

[0033] A limit value is stored in a memory in the control system 6, which represents a sufficient degree of descaling. The control system 6 compares the recorded measured values ​​with the limit value according to one of the concepts explained below. If the limit value is reached, the control system 6 outputs a signal via the electronics 5. The descaling process is then complete. If the limit value is not reached, the number of cycles or the dosage of the descaling agent can be increased in the same or a subsequent descaling process until the limit value is reached.

[0034] Figure 2 shows in a Cartesian coordinate system a first concept for the detection of a descaling process: A solid line shows a fluid flow 8 and a broken line and a time-shifted line a fluid flow in a flow heater according to Fig. 1introduced heating power 9 as a function of a time t. The fluid flow 8 is generated cyclically, i.e. it has pulse peaks 19, which are followed by peaks 21 of the heating power 9. Between the pulse peaks 19, the fluid flow 8 is not zero, but considerably lower than at the pulse peaks 19. The fluid flow 8 and the introduced heating power 9 occur in repeating cycles, each of which includes a pulse peak 19 and a phase 20 of low fluid flow 8 or a phase 22 of switched off heating power 9. The amplitude of the pulse peaks 19 and the respective duration of the fluid flow 8 during a cycle are constant during the descaling process. The amplitude 21 of the introduced heating power 9 is also constant. In contrast, the control arrangement reduces the duration Δt during which the heating energy is applied during the descaling process, and the peaks 21 of the heating power 9 become narrower.

[0035] Figure 2also shows a measurement curve 11 of the second temperature sensor 4 during the descaling process. It is operated continuously. Curve 11 corresponds to a sinusoidal or damped oscillation with an amplitude ΔT that decreases over time t. This is because the temperature maximum of the measurement curve 11 decreases due to the continuously shortened heating phase. The temperature minimum also increases slightly over time t because, as the limescale layer decreases, heating energy increasingly penetrates the descaling agent due to its mass inertia, even when the heating is switched off.

[0036] The shortening of the time intervals for applying the heating power 9 is based on the temperature currently measured at the temperature sensor 4. As soon as it reaches a reference value 12 of, for example, 60°, the heating power is switched off. The inertia of the heater ensures further heating of the descaling agent up to a maximum in the measurement curve 11. After a predetermined period of time has elapsed, the control arrangement 6 switches the instantaneous water heater back on, whereupon the measurement curve 11 reaches a minimum. The decreasing limescale layer allows for an increasingly more effective temperature transition, which is why the time between switching on and reaching the reference value can be shortened with the same heating power.

[0037] Because the removal of the limescale layer also leads to a damping of the oscillation of the measurement curve, for example both reducing the maxima of the measurement curve 11 and increasing the minima, the decreasing difference or amplitude ΔT can indicate the progress of the decalcification.

[0038] A limit value for the amplitude ΔT is stored in the control arrangement 6. The control arrangement 6 determines the actual amplitude ΔTx by calculating the difference between two values ​​of the second temperature sensor 4 within a cycle, for example, from the difference between the temperature maximum and the temperature minimum of the same cycle. Figure 2Measurements of the amplitude ΔT1 at the beginning of the descaling process and ΔT2 in the middle of the descaling process are shown. The control system 6 compares the measured difference value with the stored limit value for ΔT. If the determined amplitude ΔTx corresponds to or falls below the stored limit value for ΔT, the control system 6 outputs a signal via the electronics 5 indicating that the descaling process is complete.

[0039] As an alternative to the stored limit value for the amplitude ΔT, the stored limit value is a time value Δt for the duration of the applied heating energy per cycle. The control system determines the actual duration of the applied heating power 9 based on the reference value 12. As described above, the duration of the applied heating power 9 decreases from cycle to cycle during the descaling process due to the decreasing limescale layer. If the duration of the applied heating power has been reduced to the point where it corresponds to the time value Δt, the limescale layer has been sufficiently reduced and the descaling process can be successfully completed. Figure 2 Δt is shown as an example at the end of the decalcification process.

[0040] In Figure 3 is carried out as in Figure 2 the fluid flow 17 in constant pulse peaks. In contrast to Figure 2 will be in Figure 3the duration Δt of the introduced heating energy 9 is not shortened. The values ​​of the two temperature sensors 3, 4 are determined continuously. This results in a sinusoidal curve 14 for the values ​​of temperature sensor 3 and a sinusoidal curve 15 for the values ​​of temperature sensor 4. The cyclical switching off of the heating power 18 and the fluid flow 17 results in the sinusoidal course of the two measuring curves 14, 15. During a cycle, descaling agent enters the instantaneous water heater with pulse peaks 23 at the beginning of the cycle. After these pulse peaks 24, there is a continuous fluid flow 17. The pulse peaks 24 are significantly higher than the continuous fluid flow. The descaling agent is heated after the pulse-like fluid flow 24 by the introduction of a heating power 18. After a time t stored in the control arrangement, the heating power 18 is switched off.Due to the inertia of the heating power, the values ​​of the two temperature sensors initially rise during a cycle and then fall again with a time delay when the heating power is switched off.

[0041] The measurement curve 15 of the second temperature sensor 4 rises overall during descaling because the applied heating power 18 is not reduced over time t, and as the limescale layer decreases, more heating energy per cycle enters the descaling agent. The measurement curve 14 of the first temperature sensor 3, on the other hand, exhibits a slightly downward trend, because as the limescale layer decreases, the heating power 9 reaches the flowing descaling agent more quickly and is therefore increasingly less radiated from the housing of the instantaneous water heater 1. Over the course of the cycles, the measurement curves 14, 15 of the two temperature sensors 3, 4 converge to a common value 16.

[0042] An absolute temperature value of the second temperature sensor 4 is stored in the control system as limit value 25. Limit value 25 represents sufficient removal of the limescale layer in the instantaneous water heater. During the descaling process, the control system compares the measured value of the second temperature sensor 4 with limit value 25. The descaling cycles are repeated until limit value 25 is reached. When limit value 25 is reached, the control system 6 outputs a signal via the electronics 5 indicating that the descaling process is complete. List of reference symbols

[0043] 1Instant water heater 2Outlet 3Inlet sensor / first temperature sensor 4Outlet sensor / second temperature sensor 5Electronics / signal generator 6Control arrangement 7Fresh water inlet 8Fluid flow 9Heating power 11Measurement curve of the second temperature sensor 12Guideline value 13Limit value 14Measurement curve of the first temperature sensor 15Measurement curve of the second temperature sensor 16Converged value 17Fluid flow 18Heating power 19Pulse peaks of fluid flow 20Phase of low fluid flow 21Amplitude of the applied heating power 22Phase of no applied heating power 23Pulse peaks of fluid flow 24Limit value ΔTAmplitude ΔtTime value tTime

Claims

1. Method for descaling a hot beverage appliance, which comprises an electrical instantaneous water heater (1), a temperature sensor at an outlet of the instantaneous water heater (1) as output sensor (4), a signal emitter (5) and a control or regulation arrangement (6), with the following method steps: a) starting the descaling method, b) generating a cyclical flow (8, 17) and cyclical introduction of a heat output (9, 18), wherein the heat output is introduced in a pulse-like manner after each pulse peak of the flow, wherein, during each cycle, c) at least one value at the output sensor (4) is determined, d) the value, or a comparison value determined from multiple values of the output sensor (4), or a regulated variable of the regulation arrangement (6), which is regulated by the regulation arrangement (6) as a function of a temperature value captured at the output sensor (4), is compared with a limit value stored on the device side, e) the cycles are repeated until the limit value (13, 25) is at least reached, and in response a first signal is output, that the descaling method has finished successfully.

2. Method according to claim 1, characterised in that the limit value (25) stored on the device side corresponds to an absolute temperature value.

3. Method according to claim 1, characterised in that the limit value stored on the device side corresponds to a time value.

4. Method according to claim 1, characterised in that the limit value (13) stored on the device side corresponds to a difference between two temperature values.

5. Method according to claim 4, characterised in that the control arrangement (6), in a step i) after step c), captures a second value of the output sensor (4), forms a difference value (ΔT) therefrom and compares the difference value (ΔT) with the limit value (13) according to claim 4.

6. Method according to claim 5, characterised in that the control arrangement (6), in step c), continuously captures the temperature values of the output sensor (4), ascertains a minimum and a maximum of the values, forms a difference value (ΔT) therefrom and compares the difference value (ΔT) with the stored limit value (13) according to claim 4.

7. Method according to claim 1 for descaling a hot beverage appliance with a further temperature sensor (3), which is referred to as input sensor and is located on a surface of the instantaneous water heater, in contrast to the output sensor (4), characterised in that, in a step ii) after step c), a value of the input sensor (3) is determined.

8. Method according to claim 7, characterised in that the control arrangement (6), in a step iii) after step c), determines a difference value between the value of the output sensor (4) and the input sensor (3) and compares the difference value with the stored limit value (16) according to claim 4.

9. Method according to one of the above claims, characterised in that the descaling method is cancelled before the limit value (13, 25) is reached and a signal is output, that the descaling method has not finished successfully.

10. Hot beverage appliance, configured for performing the above method according to claim 1 to 6 and claim 9, with an electrical instantaneous water heater (1), a signal emitter (5), a control or regulation arrangement (6) and precisely one temperature sensor.