Dosing control device and dosing control method for a dishwasher

Abstract

A dosing control device is intended for use in a dishwasher comprising a tank. The dosing control device or the dishwasher comprises a dosing unit for dosing a detergent for a cleaning cycle of the dishwasher. The dosing control device or the dishwasher comprises a determination unit for determining a concentration of the detergent in the tank. The dosing control device is configured to iteratively activate and deactivate the dosing of the detergent by the dosing unit based on the concentration of the detergent determined by the determination unit.

Description

[0001] The present invention relates to a dosing control device and a dosing control method for a dishwasher.

[0002] Conventional dishwashers often use solid detergents to create a cleaning solution. A common dosing method involves spraying a water jet into a cartridge containing the solid detergent, which is permeable to liquids on the bottom. This dissolves the detergent in the cartridge. This solution is collected and piped into the tank containing the wash solution. However, such conventional dishwashers have the disadvantage that the detergent dissolves at different rates in the liquid medium, depending on the water temperature, the moisture content of the granules / preparation, etc. In addition, there are different detergents that dissolve better or worse in the washing medium due to their different chemical properties.The fill level of the cartridge also influences how quickly the desired detergent solution can be produced (in terms of concentration and speed of the dissolving process). This is reflected in different rinsing behavior from the cartridges, as well as in different final detergent concentrations in the machine. This results in a large variance of conditions that must be managed by the dosing control, with the following problems in particular occurring: 1) The creation of models that describe the dissolving behavior of the solid detergent during the spraying process in order to precisely predict the dosed quantities and the resulting rinse solution concentrations is not possible due to unknown variance. 2) The measuring section is much slower / slower than the controlled system. Therefore, a sufficiently precise and stable control loop for dosing is not possible in conventional dishwashers.In particular, high overshoots occur when using a 2-point controller in the case of a readily soluble cleaner.

[0003] It is an object of the present invention to provide a dosing control device, a dishwasher and a dosing control method to improve user-friendliness taking into account the desired applications.

[0004] The above object is achieved by a dosing control device according to claim 1, a dishwasher according to claim 16, and a dosing control method according to claim 17. Claims 2 to 15 relate to particularly advantageous implementations of the dosing control device according to claim 1.

[0005] The present invention relates to a dosing control device for a dishwasher, in particular a commercial dishwasher. The dishwasher can be configured for cleaning dishes in a cleaning process or rinsing process. The cleaning device comprises a tank, in particular a rinsing tank or wash tank. The dosing control device or the dishwasher comprises a dosing unit for dosing a cleaning agent for a cleaning process of the dishwasher. The dosing control device or the dishwasher comprises a determination unit for determining a concentration of the cleaning agent in the tank. The dosing control device is configured to iteratively activate and deactivate the dosing of the cleaning agent by the dosing unit based on the concentration of the cleaning agent determined by the determination unit.The cleaning agent can in particular be a solid cleaner, a liquid cleaner with a long control path, a cleaner in gel form or a highly concentrated cleaner.

[0006] The dosing control device can be designed (at least partially or completely) separately from or spatially separated from the dishwasher, or it can be integrated (at least partially or completely) into the dishwasher. The dosing control device can receive as input the concentration of the detergent in the tank determined by the determination unit and control the dosing unit based on this.

[0007] The dosing unit may, in particular, comprise a spray unit configured to spray fresh water into a cartridge containing a solid cleaner, such that a cleaning fluid is formed by dissolving the solid cleaner in the fresh water and drains from the cartridge into the tank, as described further below. The dosing unit may, in particular, comprise a solenoid valve that can be opened or closed to allow or prevent the spraying of fresh water into the cartridge, as also described further below.

[0008] The determination unit can calculate the concentration of the cleaning agent, in particular from a measured conductivity of the cleaning liquid or wash liquor in the tank, as described further below. The determination unit can, in particular, be configured to determine the concentration of the cleaning agent in the tank as a function of time or to determine it continuously.

[0009] In a first iteration cycle or first dosing cycle (e.g. starting from a state in which dosing of the cleaning agent by the dosing unit is deactivated), the dosing control device is configured to activate the dosing of the cleaning agent as soon as the concentration determined by the determination unit reaches or falls below a first threshold value at a first time.

[0010] In the first iteration cycle, the dosing control device is further configured such that, when the concentration determined by the determination unit reaches or falls below the first threshold, the dosing control device determines a maximum dosing time. The maximum dosing time is based on a predicted increase value, the first threshold, or a first concentration of the cleaning agent determined by the determination unit at the first time, and a second threshold. The second threshold is greater than or equal to the first threshold.

[0011] The predicted increase value may correspond to an expected increase in the concentration of the detergent in the tank (between the first time point and a third time point after the first time point, as described below) per dosing time (time between activating and deactivating the detergent dosing, as described below) in the first iteration cycle. In the first iteration cycle, the predicted increase value may be a predetermined value or a value determined during initialization of the dosing control device.

[0012] In the first iteration cycle, the dosing control device is further configured to deactivate the dosing of the cleaning agent as soon as a deactivation condition is met at a second time. The second time (t2) can, in particular, be after the first time (t1). The deactivation condition is met at least when the maximum dosing time (Δt) has elapsed since the first time; in this case, in particular, the following applies: t2 = t1 + Δt.

[0013] In the first iteration cycle, the dosing control device is further configured such that, if the deactivation condition is met, the dosing control device determines an updated predicted slope value for use as the predicted slope value in a second iteration cycle or second dosing cycle following the first iteration cycle. Thus, in the second iteration cycle, the dosing control device may operate as described above for the first iteration cycle, except that the predicted slope value is replaced by the updated predicted slope value. Thus, in the second iteration cycle, the predicted slope value may be set to the updated predicted slope value.The updated forecast increase value is based on the first time point, the second time point, the first threshold or the first concentration, and a second concentration of the cleaning agent determined by the determining unit at a third time point after the first time point.

[0014] The updated predicted increase value may correspond to an actual increase in the concentration of the cleaning agent in the tank (between the first time point and the third time point) per dosing time (time between activating and deactivating the dosing of the cleaning agent) determined in the first iteration cycle. Furthermore, the updated predicted increase value may correspond to an expected increase in the concentration of the cleaning agent in the tank (between the first time point and the third time point) per dosing time in the second iteration cycle.

[0015] The dosing control device according to the invention enables extremely precise and efficient dosing of the cleaning agent. In particular, the dosing of the cleaning agent, especially the dosing time and thus the amount or volume of the dosed cleaning agent per iteration cycle, can be automatically adjusted in an iterative process to the concentration of the cleaning agent in the tank determined by the determination unit. When using solid cleaners, the dosing can be adjusted, in particular, to the different dissolving behavior of the solid cleaner (e.g., depending on the type of solid cleaner, the water temperature, the moisture content of the solid cleaner, the fill level of the cartridge, etc.).

[0016] In particular, the fact that the dosing control device activates the dosing of the cleaning agent as soon as the concentration determined by the determination unit reaches or falls below the first threshold ensures that the concentration of the cleaning agent in the tank does not fall below the first threshold or does not fall significantly below it. In particular, the first threshold can be greater than or equal to a desired minimum value for the concentration of the cleaning agent in the tank, so that the desired minimum value of the concentration is not undercut.

[0017] In particular, by the dosing control device determining the maximum dosing time based on the forecast increase value, the first threshold value, or the first concentration of the cleaning agent determined at the first time by the determination unit, and the second threshold value, and by the dosing control device deactivating the dosing of the cleaning agent as soon as the deactivation condition is met, wherein the deactivation condition is met at least when the maximum dosing time has elapsed since the first time, it is further achieved that the concentration of the cleaning agent in the tank does not exceed, or does not significantly exceed, the second threshold value. In particular, the second threshold value can be less than or equal to a desired maximum value of the concentration of the cleaning agent in the tank, so that the desired maximum value of the concentration is not exceeded.This way, overshoots, where the concentration of the cleaning agent exceeds the desired maximum value, can be avoided.

[0018] Thus, a desired target interval for the concentration of the cleaning agent in the tank (interval between the first threshold or the desired minimum value and the second threshold or the desired maximum value) or a desired target value for the concentration (if the first threshold is equal to the second threshold) can be reached quickly and efficiently and kept constant. If the second threshold is greater than the first threshold or the distance between the second threshold and the first threshold is sufficiently large, this has the particular advantage that there is no constant activation and deactivation of the dosing. A minimum distance between the second threshold and the first threshold can depend in particular on measurement noise of the measuring unit (conductivity) and a switching cycle frequency of the dosing unit (durability).

[0019] The alternative, in which the maximum dosing time is determined based on the first threshold, has the advantage that the first concentration of the cleaning agent does not have to be determined again by the determination unit at the first time. In particular, the first threshold can be equal to or substantially equal to the first concentration or serve as an approximation for the first concentration.

[0020] Furthermore, the alternative in which the maximum dosing time is determined based on the first concentration of the cleaning agent determined by the determination unit at the first time has the advantage that the updated forecast increase value can be determined particularly accurately. This is particularly advantageous if, at the first time, the first concentration determined by the determination unit already falls below or significantly falls below the first threshold, e.g., due to a delayed reaction of the dosing control device to reaching the first threshold.

[0021] In particular, by the dosing control device determining an updated predicted slope value for use as the predicted slope value in a second iteration cycle following the first iteration cycle, the precision of the predicted slope value and thus the precision and efficiency of the dosing of the detergent is improved from the first cycle to the second cycle or remains consistently precise and efficient in each cycle.

[0022] Furthermore, the updated predicted increase value is based on actually determined concentrations of the cleaning agent in the tank. Thus, the dosing control device according to the invention enables efficient and precise dosing regardless of the type of cleaning agent used (e.g., regardless of how quickly a solid cleaner dissolves in fresh water). The variable dosing time determined by the dosing control device makes it possible to adaptively use both poorly soluble and readily soluble powder cleaners as cleaning agents with the same control system, since it is possible to provide a cleaning fluid with a defined concentration of the cleaning agent in the tank with minimal deviations (overshoots or undershoots).

[0023] Furthermore, the dosing agent is dosed more evenly and thus the dosing agent is used and distributed more efficiently. For the user, the cleaning result achieved is therefore more consistent. This also offers considerable advantages for the cleaning result, as the concentration of lye to be rinsed off (cleaning liquid) is more constant and thus the rinsing can be optimally adjusted to this lye volume. The detergent concentration of the rinse solution can be set and maintained more precisely. Therefore, a lower average concentration is sufficient to obtain consistently clean dishes, as the concentration fluctuations between minimum and maximum concentrations of the detergent are smaller. This also results in the economic advantage that less detergent is needed and a defined amount of detergent (e.g.from a cartridge) lasts longer and fewer cartridges have to be purchased and disposed of for the same amount of cleaned dishes.

[0024] Furthermore, calibration is not necessary with the dosing control device according to the invention, as the dosing control device automatically adjusts the detergent dosage to the desired concentration interval. Furthermore, the dosing control device can operate independently of other machine signals. The dosing control is not machine-dependent and can be applied to machines other than dishwashers.

[0025] In summary, the dosing control device according to the invention improves the efficiency and accuracy of dosing and thus user-friendliness.

[0026] In a preferred embodiment, the third time point and the first time point are separated by a predetermined period. This has the advantage that the third time point and thus the second concentration of the cleaning agent can be determined particularly easily, without the need to perform additional measurements or determine additional concentration values. This makes dosing more error-tolerant to short-term disturbances in the concentration measurement signal. This increases the reliability of dosing.

[0027] In a preferred embodiment, the second concentration determined by the determination unit at the third time point is a maximum concentration of the cleaning agent in the tank within the first iteration cycle (e.g., within the interval from the first time point of the first iteration cycle to the first time point of the second iteration cycle). In particular, the determination unit can be configured to determine the concentration of the cleaning agent in the tank as a function of time or to determine it continuously, and this function can have a maximum within the first iteration cycle at the third time point, wherein the value of the maximum is the second concentration.

[0028] This enables particularly precise dosing of the cleaning agent, where the second concentration does not exceed the second threshold, or only slightly, or does not exceed the desired maximum value. Since the second concentration is a maximum concentration within an iteration cycle, this means that the cleaning agent concentration does not exceed the second threshold, or only slightly, or does not exceed the desired maximum value at any time within the iteration cycle. This achieves a particularly reliable and precise adjustment of the cleaning agent concentration within the target interval.

[0029] In a preferred embodiment, the maximum dosing time (Δt) is a quotient of: a difference between the second threshold value (c2_s) and the first threshold value (c1_s) or the first concentration (c1), and the predicted increase value (a). Thus, the maximum dosing time is given by Δt=(c2_s−c1_s) / a, or Δt=(c2_s−c1) / a.

[0030] This has the advantage that the maximum dosing time can be determined particularly easily. This calculation of the maximum dosing time is particularly advantageous when the increase in concentration in the tank depends linearly or approximately linearly on the dosing time and the predicted increase value corresponds exactly or approximately to the actual increase quotient or increase value, i.e., when the following applies exactly or approximately: c2=c1+a*Δt.

[0031] In this case, (2) and (3) result in the relation c2=c2_s, This means that at the third time, the concentration of the cleaning agent in the tank reaches the second threshold exactly or approximately. In particular, the closer the predicted increase value is to the actual increase in concentration per dosing time, the more accurately the second threshold is reached at the third time.

[0032] Calculating the maximum dosing time based on equation (1) further has the advantage that the first concentration of the cleaning agent at the first time point does not need to be determined by the determination unit. In particular, the first threshold value can be equal to or substantially equal to the first concentration or serve as an approximation for the first concentration.

[0033] In a preferred embodiment, the updated forecast increase value (a_neu) is a quotient of: a difference between the second concentration (c2) and the first threshold value (c1_s) or the first concentration (c1), and a difference between the second time (t2) and the first time (t1). Thus, the updated forecast increase value is a_neu=(c2−c1_s) / (t2−t1), or a_new=(c2−c1) / (t2−t1).

[0034] This has the advantage that the updated forecast increase value can be determined particularly easily. Furthermore, the updated forecast increase value, as given above, provides a particularly precise forecast for the increase in the concentration of the cleaning agent in the tank per dosing time. The updated forecast increase value can thus be used as the forecast increase value in the second iteration cycle to precisely calculate the dosing time as described above.

[0035] Calculating the updated predicted increase value based on equation (5) also has the advantage that the first concentration of the cleaning agent at the first time point does not need to be determined by the determination unit. In particular, the first threshold value can be equal to or substantially equal to the first concentration or serve as an approximation for the first concentration.

[0036] In a preferred embodiment, the updated forecast slope value (a_neu) is a weighted average of the forecast slope value (a) and a cycle slope value (a_cycl), wherein the cycle slope value is based on the first time point (t1), the second time point (t2), the first threshold value (c1_s) or the first concentration (c1), and the second concentration (c2). In particular, the updated forecast slope value can be given by: a_neu=(a*N+a_cycl) / (N+1), where N is a natural number, preferably N = 1, N = 2, N = 3, N = 4 or N = 5. The cycle increase value (a_cycl) can be a quotient of: a difference between the second concentration (c2) and the first threshold value (c1_s) or the first concentration (c1), and a difference between the second time (t2) and the first time (t1): a_cycl=(c2−c1_s) / (t2−t1), or a_cycl=(c2−c1) / (t2−t1).

[0037] This has the advantage of using a predicted increase value averaged over several iteration cycles, thus avoiding strong fluctuations or variations in the predicted increase value recalculated in each iteration cycle. This further improves the accuracy of the dosing.

[0038] In a preferred embodiment, the deactivation condition is further met if the concentration determined by the determination unit reaches or exceeds the second threshold. In this case, dosing is deactivated, even if the maximum dosing time has not yet elapsed since the first time. This has the advantage of preventing excessive dosing of the cleaning agent, in particular an excessive increase in the concentration of the cleaning agent in the tank above the second threshold.

[0039] In a preferred embodiment, the dishwasher further comprises a machine control, and the deactivation condition is further met if the dosing control device receives a signal from the machine control indicating that dosing is not permitted. In this case, dosing is deactivated, even if the maximum dosing time has not yet elapsed since the first time. This can prevent further dosing of the detergent, e.g., if a cleaning process is aborted by a user or an error condition occurs with regard to the dishwasher or the cartridge containing the detergent. In this case, the machine control can send a signal to the dosing control device indicating that dosing is not permitted. Thus, an incorrect cleaning process or damage to the dishwasher can be avoided.This increases security and user-friendliness.

[0040] In particular, the dishwasher can be configured to output signals according to a convention (FILL, WASH, RINSE). These signals can reflect machine states and can represent an enable or permission for dosing. A (e.g., external) dosing control device can use these signals to control / enable dosing. In addition to these signals, a dosing control device can install a determination unit or a conductivity sensor in the tank to measure the detergent concentration. If a dosing control device has the WASH signal and a determination unit or a conductivity sensor in the tank and a dosing unit or a solids dosing device available, the dosing control described above can be implemented on it. Additional machine states are not mandatory.

[0041] In a preferred embodiment, the maximum dosing time is further based on the amount of fresh water or solvent supplied to the tank, or on the amount of cleaning liquid or wash liquor present in the tank or drained from the tank. Since all process events in the dishwasher (e.g., a pump will soon be switched on or off, the tank level will drop or rise, the gradient of the detergent concentration in the tank, etc.) are known to the machine control system, it can already make predictions for the upcoming iteration cycle, for example, how much fresh water is expected to be added to the tank to be dosed by then. Such predictions can be incorporated into the calculation of the dosing time (Δt).

[0042] This makes it possible to precisely dose the cleaning agent even if the concentration of the cleaning agent in the tank changes due to the addition of fresh water to the tank or the removal of cleaning liquid (solution of the cleaning agent) from the tank.

[0043] In a preferred embodiment, the dishwasher further comprises a machine control system. If the dosing of the detergent is deactivated and the dosing control device receives a signal from the machine control system indicating that dosing is not permitted, the dosing control device is configured to prevent activation of the dosing of the detergent. Thus, even if the concentration determined by the determination unit reaches or falls below the first threshold value, activation of the dosing can be prevented. In particular, dosing can be prevented until the dosing control device receives a signal from the machine control system indicating that dosing is permitted. Thus, dosing of the detergent can be avoided, e.g.If a cleaning cycle is interrupted by a user or an error condition occurs with the dishwasher or the cartridge containing the detergent. In this case, the machine control system can send a signal to the dosing control device indicating that dosing is not permitted. This can prevent an incorrect cleaning cycle or damage to the dishwasher.

[0044] In a preferred embodiment, the cleaning agent is a solid cleaner. The dosing unit further comprises a receiving unit for inserting a cartridge containing the solid cleaner into the receiving unit and a spray unit for spraying fresh water into the cartridge, such that a cleaning liquid is formed by dissolving the solid cleaner contained in the cartridge in the fresh water and drains from the cartridge into the tank. The dosing control device is further configured to activate dosing of the cleaning agent from the cartridge by enabling spraying of fresh water by the spray unit and to deactivate dosing of the cleaning agent from the cartridge by preventing spraying of fresh water by the spray unit.Particularly preferably, the dosing unit comprises a solenoid valve, and the dosing control device is configured to enable the spraying of fresh water by the spray unit by opening the solenoid valve and to prevent the spraying of fresh water by the spray unit by closing the solenoid valve. Thus, the dosing can be adapted to the dissolving behavior of the solid cleaner (e.g., depending on the type of solid cleaner, the water temperature, the moisture content of the solid cleaner, the fill level of the cartridge, etc.).

[0045] In a preferred embodiment, the cleaning agent is a solid cleaner. The determination unit comprises a measuring unit for measuring the conductivity of a cleaning liquid in the tank, wherein the cleaning liquid is a solution of the solid cleaner, and a calculation unit for calculating the concentration of the solid cleaner in the tank based on the measured conductivity of the cleaning liquid. This allows for a particularly precise and efficient determination of the concentration of the solid cleaner in the tank and thus a particularly precise and efficient control of the dosage.

[0046] The present invention further relates to a dishwasher with a dosing control device (for this dishwasher) as described above. The dosing control device can be implemented by various components of the dishwasher, in particular electronic and hardware components, software components, or combinations thereof. As described above, this dishwasher improves the efficiency and accuracy of dosing and thus user-friendliness.

[0047] The present invention further relates to a dosing control method for controlling a dosage of a detergent for a cleaning process of a dishwasher, wherein the dosing control method comprises: determining, by a determining unit, a concentration of the detergent in a tank of the dishwasher; and iteratively activating and deactivating the dosage of the detergent based on the concentration of the detergent determined by the determining unit; wherein the dosing control method comprises, in a first iteration cycle: activating the dosage of the detergent as soon as the concentration determined by the determining unit reaches or falls below a first threshold value at a first time;If the concentration determined by the determination unit reaches or falls below the first threshold, determining a maximum dosing time, wherein the maximum dosing time is based on a forecast increase value, the first threshold, or a first concentration of the cleaning agent determined by the determination unit at the first time, and a second threshold, wherein the second threshold is greater than or equal to the first threshold; deactivating the dosing of the cleaning agent as soon as a deactivation condition is met at a second time, wherein the deactivation condition is met at least when the maximum dosing time has elapsed since the first time;and if the deactivation condition is met, determining an updated forecast slope value for use as the forecast slope value in a second iteration cycle following the first iteration cycle, wherein the updated forecast slope value is based on the first time point, the second time point, the first threshold value, or the first concentration, and a second concentration of the cleaning agent determined by the determining unit at a third time point after the first time point;

[0048] All features of the dosing control device described above can be implemented analogously in the dosing control method according to the invention, and the dosing control method has the same technical advantages as the dosing control device. Thus, the efficiency and accuracy of dosing and thus user-friendliness are improved.

[0049] These and other features and advantages of the invention will become clear from the accompanying drawings, which show particularly advantageous embodiments. They show: Fig. 1A shows a dosage of the cleaning agent by an embodiment of the dosage control device according to the invention when the cleaning agent is a readily soluble solid cleaner; Fig. 1B shows a dosage of the cleaning agent by an embodiment of the dosage control device according to the invention when the cleaning agent is a poorly soluble solid cleaner; and Fig. 2 shows the operation of an embodiment of the dosing control device according to the invention.

[0050] Fig. Figure 1A shows the dosage of the detergent by an embodiment of the dosage control device according to the invention, when the detergent is a readily soluble solid detergent. The solid curve ("Invention") shows the time course of the concentration of the solid detergent in the tank with the dosage control device according to the invention, and the dashed curve ("Comparative Example") shows the time course of the concentration of the solid detergent in the tank with a conventional dishwasher that uses a conventional 2-point controller to control the dosage. Fig. Figure 1B shows the dosage of the detergent by an embodiment of the dosage control device according to the invention when the detergent is a poorly soluble solid detergent. The solid curve ("Invention") shows the time course of the concentration of the solid detergent in the tank with the dosage control device according to the invention, and the dashed curve ("Comparative Example") shows the time course of the concentration of the solid detergent in the tank with a conventional dishwasher that uses a cyclic, fixed dosage time.

[0051] In Fig. 1A and Fig. 1B, the dosing of the cleaning agent by the dosing unit is initially deactivated (at the origin of the time axis). In the first iteration cycle (e.g., the interval from the first, earliest time point designated t1 to the second, subsequent time point designated t1), the dosing control device activates the dosing of the cleaning agent as soon as the concentration determined by the determination unit, at the first time point t1, reaches or falls below the first threshold c1_s. This is illustrated by the vertically ascending line at t1 (part of the dashed bar from t1 to t2). The dosing control device then determines the maximum dosing time Δt based on a forecast increase value a, the first threshold c1_s, or a first concentration c1 of the cleaning agent determined by the determination unit at the first time point t1, and a second threshold c2_s.

[0052] In the first iteration cycle, the dosing control device deactivates the dosing of the cleaning agent as soon as a deactivation condition is met, at the second time t2. This is illustrated by the vertically descending line at t2 (part of the dashed bar from t1 to t2). In this example, the deactivation condition is met when the maximum dosing time Δt has elapsed since the first time t1. Therefore, in this example, t2 = t1 + Δt. The dosing control device then determines an updated forecast increase value a_new for use as the forecast increase value in the second iteration cycle following the first iteration cycle (e.g., the interval beginning from the second time designated t1 until a further time (not shown) at which the concentration determined by the determination unit again reaches or falls below the first threshold c1_s).The updated forecast increase value a_neu is based on the first time t1, the second time t2, the first threshold c1_s or the first concentration c1, and a second concentration c2 of the cleaning agent determined by the determining unit at a third time t3 after the first time t1.

[0053] The third time t3 and the first time t1 may be separated by a predetermined period T, as in Fig. 1A and Fig. 1B. Alternatively, as also shown in Fig. 1A and Fig. 1B, the determination unit may be configured to determine the concentration of the cleaning agent in the tank as a function of time, and the dosing control device may determine a third time t3' such that the second concentration c2' determined by the determination unit at the third time t3' is a maximum concentration of the cleaning agent within the first iteration cycle. In this case, the concentration of the cleaning agent in the tank as a function of time has a maximum at the third time t3', and the value of the maximum is the second concentration c2'.

[0054] As in Fig. 1A and Fig. 1B, the second concentration c2 determined at time t3 of the first iteration cycle is below the second threshold c2_s. This may indicate that the dosing time Δt in the first iteration cycle was too short or the predicted slope value was too high. As a result, the predicted slope value is reduced in the second iteration cycle (i.e., the updated predicted slope value used as the predicted slope value in the second iteration cycle is smaller than the predicted slope value used in the first iteration cycle). As a result, the dosing time Δt in the second iteration cycle is increased compared to the first iteration cycle. As further shown in Fig. 1A and Fig. As can be seen in Figure 1B, the second concentration c2 determined at time t3 of the second iteration cycle is above the second threshold c2_s. This may indicate that the dosing time Δt in the second iteration cycle was too short or the updated forecast increase value was too low. As a result, in the third iteration cycle (not shown in Fig. 1A or Fig. 1B) the forecast increase value can be increased again.

[0055] By iterating this method, the concentration of the cleaning agent in the tank can be adjusted within a target interval (interval between the first threshold c1_s or a desired minimum value (not shown) that is smaller than the first threshold c1_s, and the second threshold c2_s or a desired maximum value (not shown) that is greater than the second threshold c2_s. In particular, the concentration of the cleaning agent in the tank can be adjusted independently or essentially independently of the type or the current dissolving behavior of the solid cleaner, as can be seen in particular from the comparison of Fig. 1A and Fig. 1B shows: In Fig. 1B the dosing time Δt in both iteration cycles is greater than in Fig. 1A, corresponding to a smaller forecast increase value in Fig. 1B as in Fig. 1A; however, the temporal course of the concentration does not differ significantly between Fig. 1A and Fig. 1B.

[0056] The solid curve in Fig. Figure 1A thus shows how the dosing control device according to the invention functions with a readily soluble detergent. The diagram schematically shows the concentration curve in the wash liquor over time. Furthermore, the periods of rinsing the cartridge and the period time are shown. It can be seen that the concentration has hardly changed at the end of rinsing. If the spray burst was too short, this is taken into account when calculating the next spray burst. This ensures that the maximum concentration values ​​oscillate relatively small around c2_s. The oscillation results from the fact that the dissolving behavior can fluctuate slightly from spray burst to spray burst. The dashed curve in Fig. Figure 1A, on the other hand, shows the time course of the concentration in the tank when using a conventional 2-point controller. In this case, it is necessary to continue purging until c2_s is reached. This results in a large overshoot, shown in dashed lines.

[0057] The solid curve in Fig. Figure 1B further shows how the dosing control device according to the invention functions with a poorly soluble detergent. If the detergent is poorly soluble, rinsing must be significantly longer. Here, too, the rinsing time changes due to the previous increase in concentration in the wash liquor. The dashed line in Fig. Figure 1B, on the other hand, shows an attempt to control the concentration using a fixed dosing time and cycle time, adjusting it so that a highly soluble detergent works satisfactorily. In this case, it is no longer possible to achieve the desired concentration with the poorly soluble detergent.

[0058] Fig. Figure 2 shows the operation of an embodiment of the dosing control device according to the invention. A dosing cycle proceeds as follows: • As soon as the concentration of the solid cleaner in the wash liquor determined by the determination unit has fallen below the first threshold value c1_s at a first time t1, a timeout (maximum dosing time Δt) for the time of rinsing of cleaning agent from the cartridge is determined from the following variables: increase in concentration per rinsing time (forecast increase value a); current, ie at the first time t1, determined concentration of the solid cleaner in the wash liquor (first concentration c1); and second threshold value of the concentration c2_s. • The calculation of the TimeOut time corridor can be done linearly, for example: Δt = (c2_s - c1) / a. • Now the rinsing process begins and the starting time (first time t1) is recorded. • If c2_s is reached before the timeout (before the maximum dosing time Δt has elapsed), the rinsing is stopped and the stop time (second time t2) is recorded. • If the TimeOut expires, even without c2_s being reached, the rinsing is stopped and the stop time (second time t2) is recorded. • A suitably determined period T is defined. The period T can be predetermined. Alternatively, it can also be varied. To do this, the increase in conductivity or the concentration of the cleaning agent in the tank is monitored in order to extend or shorten the period T, if possible, until the time at which the maximum cleaning agent concentration is reached. The system then waits until the third time t3 = t1 + T is reached, so that the new concentration (second concentration c2) can be established in the tank. • If the period time is defined constantly and this time has already been reached due to a long flushing time, no waiting is carried out. • Now the achieved concentration of the washing solution is recorded (second concentration c2). • The increase in concentration per flushing time is updated from the collected data (updated forecast increase value a_new). This can be done linearly, for example. To avoid strong fluctuations in the calculated increase value, the existing increase value can be included in a weighted manner. An example calculation: a_new = (a * 4 + (c2 - c1) / (t2 - t1)) / 5. • For the next cycle, a = a_neu is set. • Now wait until the concentration of the washing solution has dropped again and the cycle begins again.

[0059] In Fig. In Figure 2, the boxes represent states of the dosing control device. The arrows indicate conditions that must be met to transition from one state to the next. Upon entering a state, the processes described in the box are executed once. Multiple states can be combined into a higher-level box.

[0060] The processes are defined in particular as follows: - SetConfiguration(): The parameters of the controller or dosing control device are configured. - SetStartCircumstances(): The current concentration of the wash liquor (first concentration c1) and the start time (first time t1) are recorded. - CalculateDoseTime(): Based on the previous cycles, the maximum dosing time Δt is calculated. - SwitchDosageDeviceOn(): Activates the dosing (e.g. opens the solenoid valve to rinse out solid cleaner) - SwitchDosageDeviceOff(): deactivates the dosing (e.g. closes the solenoid valve) - SetStopCircumstances(): The stop time (second time t2) is recorded. - DoCycleEvaluation(): The increase in wash liquor concentration per dosing time is updated, i.e., the updated forecast increase value a_neu is calculated. This is done using the values ​​determined in the previous states and the current wash liquor concentration.

[0061] The state transition conditions are defined as follows: - “Start Command by higher level processes”: A higher-level machine process starts the control (the dosing control). - “Stop Command by higher level processes”: A higher level machine process stops the control (the dosing control). - “Allowed”: The ambient conditions of the machine allow dosing. - "!Allowed": The ambient conditions of the machine do not allow dosing. - “Required”: The concentration has dropped so low that further dosing is necessary. - “IsDoseTimeExpired”: The calculated maximum dosing time Δt has expired. - “IsMaximumConcentrationReached”: The desired maximum concentration c2_s has been reached. - “PeriodTime expired”: The period time T has expired. List of reference symbols t1 first time point t2 second time point t3, t3' third time point c1_s first threshold concentration c2_s second threshold concentration c2, c2' second concentration Δt maximum dosing time T period time

Claims

[1] Dosing control device for a dishwasher, the dishwasher comprising a tank; wherein the dosing control device or the dishwasher comprises a dosing unit for dosing a detergent for a cleaning process of the dishwasher; wherein the dosing control device or the dishwasher comprises a determination unit for determining a concentration of the detergent in the tank; wherein the dosing control device is configured to iteratively activate and deactivate the dosing of the cleaning agent by the dosing unit based on the concentration of the cleaning agent determined by the determining unit; and wherein in a first iteration cycle the dosing control device is configured such that: - the dosing control device activates the dosing of the cleaning agent as soon as the concentration determined by the determination unit reaches or falls below a first threshold value (c1_s) at a first time (t1); - if the concentration determined by the determination unit reaches or falls below the first threshold value (c1_s), the dosing control device determines a maximum dosing time (Δt), wherein the maximum dosing time (Δt) is based on a forecast increase value (a), the first threshold value (c1_s) or a first concentration (c1) of the cleaning agent determined by the determination unit at the first time (t1), and a second threshold value (c2_s), wherein the second threshold value (c2_s) is greater than or equal to the first threshold value (c1_s); - the dosing control device deactivates the dosing of the cleaning agent as soon as a deactivation condition is met at a second time (t2), wherein the deactivation condition is met at least when the maximum dosing time (Δt) has elapsed since the first time (t1); and - if the deactivation condition is met, the dosing control device determines an updated forecast increase value (a_new) for use as the forecast increase value in a second iteration cycle following the first iteration cycle, wherein the updated forecast increase value (a_new) is based on the first time (t1), the second time (t2), the first threshold value (c1_s) or the first concentration (c1), and a second concentration (c2, c2') of the cleaning agent determined by the determining unit at a third time (t3, t3') after the first time (t1). [2] Dosing control device according to claim 1, wherein the third time (t3) and the first time (t1) are separated from each other by a predetermined period time (T). [3] Dosing control device according to claim 1, wherein the second concentration (c2') determined by the determination unit at the third time (t3') is a maximum concentration of the cleaning agent in the tank within the first iteration cycle. [4] Dosing control device according to one of the preceding claims, wherein the maximum dosing time (Δt) is a quotient of: a difference between the second threshold value (c2_s) and the first threshold value (c1_s) or the first concentration (c1), and the forecast increase value (a). [5] Dosing control device according to one of the preceding claims, wherein the updated forecast increase value (a_neu) is a quotient of: a difference between the second concentration (c2, c2') and the first threshold value (c1_s) or the first concentration (c1), and a difference between the second time (t2) and the first time (t1). [6] Dosing control device according to one of claims 1 to 4, wherein the updated forecast increase value (a_neu) is a weighted average of the forecast increase value (a) and a cycle increase value (a_cycl), wherein the cycle increase value (a_cycl) is based on the first time point (t1), the second time point (t2), the first threshold value (c1_s) or the first concentration (c1), and the second concentration (c2, c2'). [7] Dosing control device according to claim 5, wherein the updated forecast increase value (a_new) is given by: a_new = (a * N + a_cycl) / (N + 1), where N is a natural number, preferably N = 1, N = 2, N = 3, N = 4 or N = 5. [8] Dosing control device according to claim 6 or 7, wherein the cycle increase value (a_cycl) is a quotient of: a difference between the second concentration (c2, c2') and the first threshold value (c1_s) or the first concentration (c1), and a difference between the second time (t2) and the first time (t1). [9] Dosing control device according to one of the preceding claims, wherein the deactivation condition is further met when the concentration determined by the determination unit reaches or exceeds the second threshold value (c2_s). [10] Dosing control device according to one of the preceding claims, wherein the dishwasher comprises a machine control; wherein the deactivation condition is further met when the dosing control device receives a signal from the machine control indicating that dosing is not permitted. [11] Dosing control device according to one of the preceding claims, wherein the maximum dosing time (Δt) is further based on an amount of fresh water supplied to the tank or on an amount of cleaning liquid present in or discharged from the tank. [12] Dosing control device according to one of the preceding claims, wherein the dishwasher comprises a machine control; wherein, when the dosing of the detergent is deactivated and the dosing control device receives a signal from the machine control indicating that dosing is not permitted, the dosing control device is configured to prevent activation of the dosing of the detergent. [13] Dosing control device according to one of the preceding claims, wherein the cleaning agent is a solid cleaner; wherein the dosing unit comprises: a receiving unit for inserting a cartridge containing the solid cleaner into the receiving unit, and a spray unit for spraying fresh water into the cartridge so that a cleaning liquid is formed by dissolving the solid cleaner contained in the cartridge in the fresh water and flows from the cartridge into the tank; and wherein the dosing control device is configured to activate a dosing of the cleaning agent from the cartridge by enabling the spraying of fresh water by the spray unit and to deactivate a dosing of the cleaning agent from the cartridge by preventing the spraying of fresh water by the spray unit. [14] The dosing control device of claim 13, wherein the dosing unit further comprises a solenoid valve; wherein the dosing control device is configured to enable spraying of fresh water by the spray unit by opening the solenoid valve and to prevent spraying of fresh water by the spray unit by closing the solenoid valve. [15] Dosing control device according to one of the preceding claims, wherein the cleaning agent is a solid cleaner; wherein the determining unit comprises: a measuring unit for measuring a conductivity of a cleaning liquid in the tank, wherein the cleaning liquid is a solution of the solid cleaner; and a calculation unit for calculating the concentration of the solid cleaner in the tank based on the measured conductivity of the cleaning liquid. [16] Dishwasher with a dosing control device according to one of the preceding claims. [17] Dosing control method for controlling a dosage of a detergent for a cleaning process of a dishwasher, the dosing control method comprising: Determining, by a determining unit, a concentration of the detergent in a tank of the dishwasher; and iteratively activating and deactivating the dosage of the cleaning agent based on the concentration of the cleaning agent determined by the determination unit; wherein the dosing control method comprises in a first iteration cycle: - activating the dosage of the cleaning agent as soon as the concentration determined by the determination unit reaches or falls below a first threshold value (c1_s) at a first time (t1); - if the concentration determined by the determining unit reaches or falls below the first threshold value (c1_s), determining a maximum dosing time (Δt), wherein the maximum dosing time (Δt) is based on a forecast increase value (a), the first threshold value (c1_s) or a first concentration (c1) of the cleaning agent determined by the determining unit at the first time (t1), and a second threshold value (c2_s), wherein the second threshold value (c2_s) is greater than or equal to the first threshold value (c1_s); - deactivating the dosing of the cleaning agent as soon as a deactivation condition is met at a second time (t2), wherein the deactivation condition is met at least when the maximum dosing time (Δt) has elapsed since the first time (t1); and - if the deactivation condition is met, determining an updated forecast increase value (a_neu) for use as the forecast increase value in a second iteration cycle following the first iteration cycle, wherein the updated forecast increase value (a_neu) is based on the first time point (t1), the second time point (t2), the first threshold value (c1_s) or the first concentration (c1), and a second concentration (c2, c2') of the cleaning agent determined by the determining unit at a third time point (t3, t3') after the first time point (t1).

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