DE102011004949B4 - Dishwasher and method for operating the same - Google Patents

Abstract

Dishwasher, in particular a household dishwasher, with a washing chamber (7) for receiving items to be washed, with a dosing device (26) for receiving cleaning agents and/or cleaning aids, with a control and/or regulating device (2) which is designed to operate the dishwasher (1) according to a washing program that can be selected from a plurality of washing programs and to at least partially open the dosing device (26) during the course of the respective washing program so that cleaning agents and/or cleaning aids reach the washing chamber (7), and with a sensor (25) for determining at least one characteristic of a washing liquid (S) circulating in the dishwasher (1), wherein the control and/or regulating device (2) is designed to determine the characteristic before opening the dosing device (26) in the form of at least one reference measurement and after opening the dosing device (26) in the form of at least one comparison measurement and to carry out the washing program on the basis of the difference (D) or another relation between the reference value determined during the reference measurement and the to select and/or modify the comparison value determined during the comparison measurement, wherein the control and/or regulating device (2) is designed to carry out the reference measurement immediately before opening the dosing device (26) and to carry out the comparison measurement after a defined period of time, in particular a period of time between 40 and 80 seconds, preferably a period of time between 50 and 70 seconds, after opening the dosing device (26).

Description

The invention relates to a dishwasher, in particular a household dishwasher, with a washing chamber for receiving items to be washed, with a dosing device for receiving cleaning agents and/or cleaning aids, such as rinse aid, with a control and/or regulating device which is designed to operate the dishwasher according to a washing program that can be selected from a plurality of washing programs and to at least partially open the dosing device during the course of the respective washing program so that cleaning agents and/or cleaning aids reach the washing chamber, and with at least one sensor for determining at least one characteristic variable of a washing liquid circulating in the dishwasher. Furthermore, a method is proposed for operating a dishwasher, in particular a household dishwasher, with a washing chamber for receiving items to be washed, with a dosing device for receiving cleaning agents and/or cleaning aids, such as rinse aid, wherein the dishwasher is operated according to a washing program selected from a plurality of washing programs, wherein the dosing device is opened at least partially with the aid of a control and/or regulating device during the course of the washing program, so that cleaning agents and/or cleaning aids reach the washing chamber, and wherein at least one characteristic variable, in particular the turbidity, the pH value, the electrical conductivity, the viscosity and/or the density, of washing liquid circulating in the dishwasher is determined with the aid of at least one sensor.

From the DE 195 37 669 A1 A dishwasher with a probe for measuring the pH value of a rinsing liquid is known, in which a corresponding rinsing program is carried out by the program control depending on the detected pH value.

From the EN 10 2009 031 433 A1 A method for operating an automatic dishwasher is known in which a degree of soiling of the items to be washed and/or the rinsing water in the dishwasher is determined with the aid of a sensor at least once at the start of a washing program, the measured degree of soiling is compared with a reference value which represents light soiling, and in the event that the degree of soiling is less than or equal to the reference value, the rinsing water temperature in a cleaning program is kept on average at ≤ 65°C, at the end of the cleaning program and/or an intermediate rinsing cycle at least rinse aid preparation is dispensed from a dosing device into the interior of the dishwasher, and a drying program immediately follows the cleaning program and/or the intermediate rinsing cycle without a rinse aid program being carried out.

One from the DE 196 50 915 B4 A known liquid-carrying household appliance has a program control which is able to identify a cleaning substance contained in the liquid with the help of the results of a conductivity measurement and to execute a corresponding predefined program depending on the measured conductivity and the type of cleaner thus identified.

From the EN 10 2007 042 076 A1 A dishwasher with a circulation pump and a control device is known, wherein the control device is designed such that it adjusts the speed of the circulation pump for a rinsing process as a function of measurement results of at least one sensor which measures at least one parameter characterizing the rinsing process.

From the WO 2006/ 010 746 A1 A method is known for the dosed addition of rinse aid during the rinsing process into the rinse liquid in the washing container of a program-controlled dishwasher, in which the rinse aid concentration of the rinse liquid is monitored by means of an optical sensor.
From the DE 34 24 711 A1 Finally, a cleaning system operated with liquid cleaning agent is known in which pairs of measured values of the electrical conductivity of the cleaning agent are determined and compared before and after it hits the object to be cleaned. When the difference between the compared individual values approaches a predetermined minimum value, the respective cleaning phase is terminated.

In order to ensure that dirty items, such as pots, dishes or cutlery, are cleaned and dried as effectively as possible during the washing program, dishwashers usually have at least one dosing device. This dosing device usually comprises several chambers that can be individually filled with cleaning agents (for example in the form of a cleaning powder) and cleaning aids (e.g. a rinse aid or a water softener). The cleaning and drying result ultimately depends to a large extent on the right cleaning agent or cleaning aid being added to the washing liquid at the right time and thus coming into contact with the items to be washed. For example, it must always be ensured that the cleaning agent during the cleaning cycle and the rinse aid during the rinsing cycle can enter the washing chamber of the dishwasher by activating the dosing device.

If the cleaning agent were mistakenly released into the rinsing chamber too late, for example during an intermediate rinse cycle following the cleaning cycle, the cleaning effect would be unsatisfactory because the respective process parameters (temperature of the rinsing liquid, duration and timing of operation of a circulation pump circulating the rinsing liquid, rinsing liquid pressure generated by the circulation pump, etc.) are optimally designed for a good cleaning result during the cleaning cycle, but not during the intermediate rinse cycle.

When using separate agents (e.g. in the form of a cleaning powder and/or a liquid rinse aid), the adjustment of the respective dosing times of the cleaning agents and/or aids is achieved by the dosing device dosing the respective agent into the washing chamber at predetermined times. However, the corresponding times only result in the desired washing result if the agents are actually available separately and can therefore also be dosed separately.

Nowadays, however, so-called tabs are increasingly being used. These are used either as single-phase tabs (which only contain a cleaning agent or a cleaning aid) or as multi-phase tabs (which usually contain various cleaning agents and aids in several layers).

Since both types are usually in the form of a pressed powder body, the dissolution of the respective active ingredients in the rinsing liquid is delayed compared to conventional cleaning powders or liquid cleaning agents or aids. In addition, in the case of multi-phase tabs, the individual active ingredients are only released at very specific times, which primarily depend on the structure of the tab. The active ingredients inside can only be released when the outer layers have gradually dissolved in the rinsing liquid. Targeted timing of the addition of the individual active ingredients, as is possible in the case of separate cleaning agents and/or aids, is not possible here. It is therefore advisable to select a different rinsing program or a rinsing program that is modified from a standard rinsing program when using a tab in order to be able to adjust the timing of the individual rinsing cycles to the release of the active ingredients contained in the tabs.

The object of the invention is therefore to propose a dishwasher and a method which allow appropriate recognition and consideration of the cleaning agents or cleaning aids used.

The object is achieved in terms of device with a dishwasher according to independent claim 1.

The dishwasher according to the invention has a control and/or regulating device for automatically carrying out operating sequences of the dishwasher. At least one washing program for carrying out or controlling a washing process, also called a washing cycle, for washing items to be washed, in particular for washing dishes, is stored in the control and/or regulating device. Advantageously, several washing programs are provided, one of which can be selected and started by the operator. This makes it possible to adapt the sequence of a washing cycle, in particular to the load size, the type of load, the degree of soiling of the items to be washed and/or to the desired duration of the washing cycle.

The stored washing programs can preferably be designed in such a way that the washing cycle controlled by them in particular comprises at least one pre-wash cycle for pre-cleaning the items to be washed, at least one cleaning cycle for thoroughly cleaning the items to be washed, at least one intermediate wash cycle for removing dirty washing liquid from the items to be washed, at least one final rinse cycle to avoid stains on the items to be washed and/or to prepare for a drying cycle, and/or at least one drying cycle for drying the items to be washed. The pre-wash cycle, cleaning cycle, intermediate rinse cycle and final rinse cycle are referred to as water-based partial wash cycles because the items to be washed placed in the washing chamber are treated with a washing liquid during their execution. The use of washing liquid is generally not intended during the drying cycle.

The items to be washed are treated with rinsing liquid in an essentially closed rinsing chamber of the dishwasher. An inlet valve is assigned to the rinsing chamber, which allows rinsing liquid to be filled into the rinsing chamber, whereby the inlet valve can be opened and closed by the control and/or regulating device in order to influence the inflow of rinsing liquid.

A rinsing liquid is understood here in particular to mean a liquid which is intended to be applied to the items to be washed in order to clean them and/or in other The rinsing liquid can also be used to heat the items to be washed, which is common during a final rinse step, for example.

The rinsing liquid that flows into the rinsing chamber via the inlet valve is usually fresh water. Depending on the operating phase of the dishwasher, the rinsing liquid in the rinsing chamber can be enriched with cleaning agents, cleaning aids such as rinse aid, and/or dirt that has been removed from the items being washed.

Furthermore, the rinsing chamber is assigned a typically electrically driven circulation pump for circulating the rinsing liquid that has been filled in, which makes it possible to remove the rinsing liquid in the rinsing chamber, e.g. from a collecting device for rinsing liquid, and to apply it to the items to be washed via a spray system assigned to the rinsing chamber. The speed of the circulation pump can be variably controlled and/or regulated by the control and/or regulating device of the dishwasher.

Finally, the dishwasher has a dosing device which can be filled with cleaning agents and/or cleaning aids (in particular by filling them into separate chambers of the dosing device).

In order to be able to take into account the type of cleaning agents and/or cleaning aids added during operation of the dishwasher, the invention provides that the control and/or regulating device is designed to determine at least one characteristic of the washing liquid circulating in the dishwasher before opening the dosing device in the form of at least one reference measurement and after opening the dosing device in the form of at least one comparison measurement and to select and/or modify the washing program on the basis of the reference value determined during the reference measurement and the comparison value determined during the comparison measurement.

The measurement provides measured values on the basis of which a conclusion can be drawn about the cleaning agent or cleaning aid used, since, as described above, the dissolving behavior of a tab differs greatly from the dissolving behavior of conventional agents that are dosed separately. If the comparison value is then compared with the reference value, a ratio is obtained that is typical for the respective cleaning agent and/or cleaning aid. Since a tab dissolves significantly more slowly than, for example, a cleaning powder and/or a gel-like rinse aid, the amount of the respective measured parameter or parameters of the rinsing liquid (for example, the turbidity or light transmittance, the pH value, the electrical conductivity, the viscosity and/or the density) will change significantly more slowly between the reference and comparison measurements when using a tab than when using separate cleaning agents and/or aids. As a result, measured values are obtained on the basis of which a washing program adapted to the respective solution behavior can be selected with the help of the control and/or regulating device or a washing program selected (in particular by the operator of the dishwasher) can be modified.

Finally, the fact that the reference measurement takes place before the dosing device is opened (and therefore before the cleaning agent and/or cleaning aid is added) ensures that any dirt that has already been introduced into the rinsing liquid during a pre-wash cycle can be taken into account. If both measurements were carried out after the dosing device was opened, the ratio would not only be determined by the solubility behavior of the added cleaning agent or cleaning aid. Rather, for example, the absolute change in the turbidity of the rinsing liquid caused by the addition of one of the agents would be smaller if the rinsing liquid already has a certain "pre-turbidity" due to the aforementioned dirt entry. The reference measurement now makes it possible to determine this "pre-turbidity" and to take it into account when assessing the ratio between the reference value and the comparison value. The reference value therefore represents a reference value, so that the cleaning agent or cleaning aid used can be identified or categorized as reliably as possible.

Finally, it should be noted at this point that the dishwasher according to the invention is not only able to distinguish between a tab and a powdered or liquid cleaning agent or cleaning aid. Rather, the measurements mentioned can also be used to distinguish between similar cleaning agents and/or cleaning aids (e.g. different cleaning powders from different manufacturers), since these generally show different dissolving behavior, resulting in characteristic reference and/or comparison values.

According to an advantageous development of the invention, the at least one sensor is a sensor for measuring the turbidity, the pH value, the electrical conductivity, the viscosity and/or the density of the rinsing liquid. Such sensors are known to the person skilled in the art and can each be individually or in combination, whereby in the latter case several reference and comparison values are available, which enable even better detection of the dissolving properties of the cleaning agents and/or cleaning aids used. The sensors are preferably located in the area of the corresponding rinsing liquid lines of the dishwasher in order to enable direct analysis of the rinsing liquid.

According to the invention, the control and/or regulating device is designed to carry out the respective reference measurement immediately before the dosing device is opened. This prevents a relevant change in the amounts of the measured parameters from occurring between the reference measurement and the opening of the dosing device. If a longer period of time were to pass between the reference measurement and the opening of the dosing device, it could not be ruled out that a change in the respective parameter would occur during this period, which could be attributed to further dirt entering the rinsing liquid. This change would ultimately not be taken into account in the reference measurement and would therefore be attributed to the subsequent addition of cleaning agents or cleaning aids. The result would be an incorrect assessment of the dissolving behavior of the agents mentioned.

According to the invention, the control and/or regulating device is designed to carry out the comparison measurement after a defined period of time, preferably a period of time between 40 and 80 seconds, in particular a period of time between 50 and 70 seconds, after the dosing device has been opened. This period of time is generally sufficient to draw a conclusion about the cleaning agent and/or cleaning aid used from the ratio of the reference and comparison values. While, for example, conventional cleaning agents have largely dissolved after less than a minute and thus cause a corresponding change in the monitored parameter, this process takes considerably longer with tablets.

According to an advantageous development of the invention, the control and/or regulating device is designed to set the time period based on the amount of the reference value. For example, it would be conceivable to extend the time period if the reference value is above a certain amount. If the rinsing liquid already has a high dirt load before the addition of cleaning agents or cleaning aids, the absolute increase in the monitored parameter, for example the turbidity of the rinsing liquid, will generally be smaller than if the rinsing liquid is more or less clear before the dosing device is opened. However, since the amounts of the monitored parameters experience the greatest changes in the first few minutes after the addition of the respective agents, an extension of the above time period would result in an increase in the difference between the reference value and the comparison value and thus in the values becoming more meaningful.

According to the invention, the control and/or regulating device is designed to select and/or modify the rinsing program on the basis of the difference or another relation or linkage or mathematical function between the reference value and the comparison value. Since the dissolution behavior has a direct effect on the absolute change in the measured parameter(s), the said difference represents a value that allows a direct conclusion to be drawn about the dissolution behavior and thus about the cleaning agent and/or cleaning aid used.

According to an advantageous development of the invention, the control and/or regulating device is designed to select an alternative rinsing program and/or to modify the rinsing program if the difference between the reference value and the comparison value is above a defined limit value. The respective limit values can be determined using corresponding measurements that can already be carried out at the factory. Several limit values can also be stored, each of which results in a different selection or adjustment of the rinsing program. For example, a limit value A can be assigned to a cleaning powder from manufacturer X, a limit value B to a cleaning gel from manufacturer Y and a limit value C to a tablet from manufacturer Z, on the basis of which an appropriately adjusted rinsing program is always selected.

According to an advantageous development of the invention, the control and/or regulating device is designed to convert the difference into a percentage deviation from the reference value and to select an alternative rinsing program and/or to modify the rinsing program if the deviation is above a defined limit value, for example above 10%, preferably above 15%. Of course, a large number of limit values can also be defined in this case, so that, for example, if the value is above 5%, rinsing program 1 is selected, if the value is above 10%, rinsing program 2 is selected, and if the value is above 20%, rinsing program 3 is selected. By relativizing the determined values, contamination of the rinsing liquid before the dosing device is opened is taken into account in particular, so that that a particularly accurate assessment of the dissolving behaviour of the added agents is possible.

According to an advantageous development of the invention, the control and/or regulating device is designed to set the limit value depending on the reference value. This is particularly advantageous if the items to be washed are pre-washed before the dosing device is opened, during which the rinsing liquid may already be enriched with contaminants. By taking these contaminants into account, which have a direct effect on the amount of the reference value, a reliable assessment of the cleaning agent or cleaning aid added is possible.

According to an advantageous development of the invention, the control and/or regulating device is designed to carry out a basic measurement of the parameter at the beginning of the rinsing program and to set the limit value taking into account the base value determined with the aid of the basic measurement. The base value is used to calibrate the respective sensor with the aid of which the relevant parameter is determined. At the beginning of the rinsing program, it can be assumed that the rinsing liquid is almost pure water, the respective parameters of which are known. These parameters are finally linked to the base value obtained during the basic measurement, so that it can always be assumed that the reference and comparison measurements provide correct measured values.

According to an advantageous development of the invention, the dishwasher has a heating device for heating the washing liquid and a temperature sensor for determining the temperature of the washing liquid, wherein the control and/or regulating device is designed to set the limit value as a function of the temperature at a defined point in time of the washing program, in particular at the point in time of the reference and/or comparison measurement. This makes it easy to take into account the fact that the dissolving behavior of the added cleaning agents and cleaning aids changes as a function of the temperature. It can therefore be assumed that the agents mentioned dissolve more quickly at higher temperatures and thus lead to a large difference between the reference and comparison values for the same period of time between the reference and comparison measurements. By taking the temperature into account, it can finally be ensured that a larger difference at a higher temperature results in the same washing program or the same change in a washing program as a smaller difference at a correspondingly lower temperature.

According to an advantageous development of the invention, the control and/or regulating device is designed to record several measured values during the reference measurement and/or the comparison measurement and to calculate an average reference value and/or comparison value from the determined measured values. This makes it easy to increase the measurement accuracy and takes into account the fact that the increase in the respective parameter after opening the dosing device is not consistently linear.

According to an advantageous development of the invention, the rinsing program comprises several rinsing cycles, e.g. in the form of a pre-rinse cycle, a cleaning cycle, an intermediate rinsing cycle, a final rinse cycle and/or a drying cycle, wherein the control and/or regulating device is designed to modify or skip individual rinsing cycles depending on the reference value and the comparison value, in particular the difference between them. In this way, a particularly fine adaptation of the rinsing program to the type of cleaning agent or cleaning aid determined with the aid of the reference and comparison measurements is possible.

According to an advantageous development of the invention, the dosing device has a filling sensor for checking whether or how much rinse aid is in the dosing device. In this way, for example, the type or amount of cleaning agent can be determined in the manner described above and the presence or amount of rinse aid can be determined with the help of the filling sensor. Based on the respective results, a precise adjustment of the washing program is finally possible.

The method according to the invention for operating a dishwasher, in particular a household dishwasher, is finally characterized in that the parameter is determined with the aid of the control and/or regulating device in the form of a reference measurement before the dosing device is opened and in the form of a comparison measurement after the dosing device is opened, and the washing program is selected and/or modified depending on the reference value determined during the reference measurement and the comparison value determined during the comparison measurement, preferably the difference between them. With regard to the advantages of this method, reference is made to the previous explanations.

The advantageous developments and refinements of the invention explained above and/or reproduced in the subclaims can - except, for example, in cases of clear dependence abilities or incompatible alternatives - individually or in any combination.

• 1 ein Ausführungsbeispiel einer erfindungsgemäßen Haushaltsgeschirrspülmaschine in einer schematischen Seitenansicht, und
• 2 den Verlauf der Lichtdurchlässigkeit einer Spülflüssigkeit in Abhängigkeit der Zeit und des eingesetzten Reinigungsmittels.

The invention and its advantageous developments and further developments as well as their advantages are explained in more detail below with the aid of drawings. They show, in a schematic principle sketch:

• 1 an embodiment of a household dishwasher according to the invention in a schematic side view, and
• 2 the course of the light transmittance of a rinsing liquid as a function of time and the cleaning agent used.

1 shows an advantageous embodiment of a dishwasher 1 according to the invention in a schematic side view. The dishwasher 1 has a control and/or regulating device 2 in which several washing programs are stored for controlling and/or regulating, ie monitoring a washing cycle. By selecting a suitable washing program, the washing cycle sequence can be adapted, for example, to the load size, the type of load, the degree of soiling of the items to be washed and/or the desired duration of the washing cycle.

The control and/or regulating device 2 is generally assigned an operating device 3, which allows an operator of the dishwasher 1 to call up one of the washing programs and thereby start it. Furthermore, the control and/or regulating device 2 can be assigned an output device 4, which enables messages to be output to the operator.

The dishwasher 1 further comprises a washing container 5, which can be closed by a door 6, so that a closed washing chamber 7 is created. In 1 the door 6 is shown in its closed position, whereby it can be brought into an open position by pivoting about an axis arranged perpendicular to the plane of the drawing.

The control and/or regulating device 2 is accommodated, for example, in a base assembly beneath the washing container 5. However, it is also possible to arrange the control and/or regulating device 2 at a different location on the dishwasher 1. The control and/or regulating device 2 could also be designed in a decentralized manner, which is understood to mean that it comprises spatially separated components which are connected via communication means in such a way that they can interact.

The dishwasher 1 has an upper dish basket 9 and a lower dish basket 10 for positioning dishes, which are each arranged on extension rails 11, 12 or other extension and/or displacement means which are fastened to opposite side walls of the washing container 5 extending in the depth direction of the washing container 5.

The washing program(s) stored in the control and/or regulating device 2 can each provide for several partial washing cycles, for example at least one pre-wash cycle, at least one cleaning cycle, at least one intermediate washing cycle, at least one final rinse cycle and/or at least one drying cycle in this order. The pre-wash cycle, cleaning cycle, intermediate washing cycle and final rinse cycle are referred to as water-bearing partial washing cycles, since during their execution the items to be washed positioned in the washing chamber 7 are treated with a washing liquid S. During the drying cycle, treatment of the items to be washed with washing liquid S is generally not provided.

In the exemplary embodiment, fresh water or inlet water ZW is used as the rinsing liquid S for treating the items to be washed, which can be taken from an external water supply device WH, in particular a drinking water supply network, and filled into the rinsing chamber 7. Typically, at the beginning of each water-bearing partial rinsing cycle, a rinsing liquid S formed from fresh inlet water ZW is filled in, which is then discharged to an external waste water disposal facility AR as waste water AW at the end of the respective partial rinsing cycle. However, it is also possible to store a rinsing liquid S from a partial rinsing cycle in a storage container (not shown) and to fill it into the rinsing chamber 7 again in a later partial rinsing cycle.

The dishwasher 1 of the 1 comprises an inlet 13, which is intended for connection to the external water supply device WH. As in 1 The external water supply device WH can be a water tap of a building-side water installation that provides pressurized inlet water ZW. The inlet 13 comprises a connector 14 that is intended for connection to the water tap. The connection can be made, for example, via a threaded arrangement, a bayonet arrangement or the like. Downstream of the connector 14, a connecting hose 15 is provided, which is preferably designed to be flexible. The downstream end of the connecting hose 15 is connected to a connector 16 that is fixed to the housing.

Downstream of the housing-fixed connector 16, a supply line 17 is provided which is connected to an inlet side of an inlet valve 18 that can be switched by means of the control and/or regulating device 2. An outlet side of the inlet valve 18 is in turn connected to a liquid inlet 19 of the rinsing chamber 7. In this way, it is possible to use the inlet 13 to guide inlet water ZW as rinsing liquid S into the interior of the rinsing chamber 7 of the dishwasher 1.

In addition to or as an alternative to the inlet valve 18 on the device, an inlet valve external to the device can be provided. It can be particularly expedient to connect the inlet valve directly to the water tap.

The rinsing liquid S flowing into the rinsing chamber 7 via the liquid inlet 19 reaches, due to its weight, a collecting device formed on a base 20 of the rinsing container 5, which can preferably be designed as a collecting pot 21. An inlet side of a circulating pump 22 (which can have a heating device 32 for heating the rinsing liquid) is connected to the collecting pot 21 in a fluid-conducting manner. Furthermore, an outlet side of the circulating pump 22 is connected to one or more spray devices, here an embodiment comprising a lower spray arm 24 and an upper spray arm 23, which makes it possible to apply rinsing liquid S to the items to be washed introduced into the rinsing chamber 7.

Furthermore, the dishwasher 1 has, in a conventional manner, a dosing device 26 which makes it possible to add cleaning agents and/or cleaning aids to the rinsing liquid S introduced into the rinsing chamber 7 in order to improve the cleaning effect and/or the drying effect of a rinsing cycle.

The cleaning and drying performance of the dishwasher 1 depends not only on the individual process parameters (temperature profile of the washing solution, start, end and duration of the individual washing cycles, etc.) but also strongly on the amount and/or type of cleaning agent or cleaning aid used.

In particular, it is important that the cleaning agent and/or cleaning aid is/are added at the right time. For example, the rinsing result would be significantly worsened if the cleaning agent was only added in the intermediate rinsing phase or if a rinse aid was added in the cleaning phase. The respective opening times of the dosing device 26 are stored in the respective rinsing program, so that when using separate cleaning agents and cleaning aids, correct addition of the individual agents is ensured by the appropriately adjusted opening of the individual chambers of the dosing device 26.

However, if so-called tabs are used, which can combine a large number of different cleaning agents and aids in one unit, the washing program must be adjusted. This is mainly due to the fact that the individual active ingredients of the tabs only come into contact with the dishes at the right time when the tabs gradually dissolve and gradually release the individual cleaning agents and aids. Rapid dissolution, as is desired when using separate cleaning agent powder, for example, in order to achieve a quick cleaning effect, is therefore not desired when using tabs.

As a result, it is therefore necessary to select the rinsing program taking into account the cleaning agents and/or aids used. While manual pre-selection of the appropriate rinsing cycle would also be possible, the solution according to the present invention allows automatic selection of an appropriate rinsing program or modification (e.g. changing temperature and/or time parameters) of a standard rinsing program depending on the cleaning agent or aid used.

The invention is based on the knowledge that, as mentioned above, tabs dissolve more slowly than cleaning agents and cleaning aids used separately. However, since the amount of certain parameters of the washing solution (e.g. turbidity, pH value, electrical conductivity, viscosity and/or density) changes depending on the cleaning agents and/or cleaning aids dissolved therein, a conclusion can be drawn about the cleaning agents and/or cleaning aids used by measuring one or more of these parameters accordingly over time.

The time dependence mentioned can be 2 which shows the turbidity of the washing solution (Y-axis) when using a tab (solid line) and alternatively when using a cleaning powder (dotted line). The turbidity is measured using a sensor 25 for measuring turbidity (see 1 ) which includes a light source and a light detector. If all the light emitted by the light source is detected by the detector, there is no turbidity. This would correspond in the 2 a value on the Y-axis (D stands for light transmittance of the rinsing liquid S) of 100%. If this value If the value is finally 0%, this would mean that all the emitted light is absorbed by the cleaning particles. The turbidity would be maximum in this case.

The typical course of the turbidity in the two cases mentioned (tab or cleaning powder) is now given by 2 . While the cleaning powder dissolves quickly in the rinsing liquid S after opening the dosing device 26 (time R) and thus causes a reduction in the light transmittance or an increase in the turbidity of the rinsing liquid S just a few seconds after its addition (see kink in the dotted curve approx. 5 seconds after the addition of the cleaning agent, marked by the letter R), the cleaning phase of the tab dissolves only very slowly, resulting in a slow increase in turbidity (solid line).

If the turbidity (or another characteristic of the washing solution that changes depending on the concentration of the cleaning agent and/or cleaning aid in the washing liquid S) is measured at a reference time before the dosing device 26 is opened (here at time t=0) and again a certain time after opening, the ratio of the two values (reference value and comparison value) makes it possible to determine which type of cleaning agent (e.g. cleaning powder or tablet) or which type of cleaning aid (e.g. liquid rinse aid or tablet) was used. A conclusion can also be drawn about the amount of agent used, since the turbidity increases more quickly the more of the respective agent gets into the washing chamber 7.

In order to take this ratio into account when selecting or modifying the rinse cycle, it is advisable, for example, to calculate the difference (in 2 referred to as D) between the reference value measured at time t=0 and the comparison value determined after opening the dosing device 26. As an alternative to the difference, another relation or a mathematical function between the reference value and the respectively assigned comparison value can also be used. If, as in this embodiment, this difference D is above a previously defined limit value, e.g. 20%, the control and/or regulating device 2 assumes that a cleaning powder has been used. If the difference D is below this value, as in the case of the solid line, it can be assumed that a tablet was used. In this case, the respective rinse cycles are adjusted accordingly. In particular, the times at which one wash cycle changes to the next (for example the transition from the intermediate rinse cycle to the final rinse cycle) are adjusted in such a way that, for example, in the case of using a tab, the final rinse cycle is started when it can be expected that the rinse aid, which is only released after a certain time by dissolving the tab, is actually in the washing liquid S.

Likewise, the length of the cleaning cycle can also be influenced accordingly. It is conceivable, for example, to extend this rinsing cycle if the measurement according to the invention has shown that a tab is being used that usually dissolves more slowly than a cleaning powder. In any case, the measurement of the corresponding parameter of the rinsing liquid S before and after opening the dosing device 26 allows a reliable statement to be made regarding the nature and/or type of cleaning agent or cleaning aid, so that the rinsing program can be selected or adjusted accordingly in order to achieve the best possible cleaning and drying result.

Finally, by measuring the reference value before opening the dosing device 26, it is ensured that the respective state of the rinsing liquid S is taken into account before the addition of the cleaning agent and/or cleaning aid. If, for example, a certain amount of dirt is already removed from the items to be washed in the pre-wash cycle, the rinsing liquid S already has a certain turbidity before the addition of the cleaning agent and/or cleaning aid during the cleaning cycle. However, by measuring this turbidity before the addition of the cleaning agent, this turbidity value is taken into account, so that only the change in turbidity attributable to the addition of the cleaning agent is taken into account when selecting or modifying the rinsing program. It is therefore of course also possible to make the ratio or the amount of the difference D, at which an alternative rinsing program is selected, dependent on the amount of the reference value, since, for example, the change in turbidity (or the other parameters of the rinsing liquid S) will be smaller if the rinsing liquid S already has a high dirt load before the dosing device 26 is opened.

Finally, the 1 The dishwasher 1 shown has a drainage device 27 which serves to pump out washing liquid S that is no longer required as waste water AW from the washing chamber 7. The drainage device 27 comprises a drain pump 28, the inlet side of which is connected to the collecting pot 21. The outlet side of the drain pump 28, however, is connected to a connecting line 29, the downstream end is connected to a housing-fixed connection 30 of the dishwasher 1.

A waste water hose 31, which is designed to be flexible, is attached to an outlet of the housing-fixed connection 30. A connection piece 8 is arranged at the downstream end of the waste water hose 31 and is intended to connect the drainage device 27 to a waste water disposal device AR. The waste water disposal device AR can be a waste water pipe of a building-side water installation. The connection between the connection piece 8 and the waste water pipe can be designed as a screw connection, a bayonet connection, a plug connection or the like.

In a final embodiment, the type of detergent is detected using a sensor 25 that is suitable for determining the turbidity of the rinsing liquid S by carrying out a reference measurement before opening the dosing device 26. After a certain time (typically: 60 seconds), a comparison measurement is carried out. If a turbidity delta of more than 10% is reached, a powder detergent has been added. If the turbidity level does not change or does not change very much, a tablet was in the dosing device 26 or in the cutlery basket. The rinsing program can then be optimally adapted to the ambient conditions (type of detergent, rinse aid).

The advantages of the invention are in particular that the parameters for adapting the rinsing program are known at an early point in time (adding detergent), that the information (rinse aid and detergent type) can be combined, and that the rinsing of the dosing device 26 can be initiated in a targeted manner.

Furthermore, the invention is not limited to the exemplary embodiments shown. Rather, all combinations of the individual features described, as shown or described in the claims, the description and the figures and insofar as a corresponding combination appears technically possible or sensible, are the subject of the invention. For example, it is conceivable to use a fill sensor 33 to detect whether or how much rinse aid is in the dosing device 26. Depending on the measured value of the fill sensor 33, it would be possible, for example, to make a pre-selection from the available washing programs. This can, for example, take into account the fact that a separate rinse aid is usually added at a different time than is the case when using tabs, where the release of the rinse aid depends on the solubility of the remaining tab components.

List of reference symbols

1

dishwasher

2

Control and/or regulating device

3

Control device

4

Output device

5

Rinse container

6

door

7

Rinsing chamber

8th

Connector

9

upper dish rack

10

lower dish rack

11

Extension rail

12

Extension rail

13

Intake

14

Connector

15

Connection hose

16

Housing-mounted connector

17

supply line

18

Inlet valve

19

Fluid inlet

20

Floor

21

Collection pot

22

Circulation pump

23

upper spray arm

24

lower spray arm

25

sensor

26

Dosing device

27

Drainage device

28

Drain pump

29

Connecting line

30

Housing-mounted connection

31

Waste water hose

32

Heating device

33

Fill sensor

WH

Water supply facility

ZW

Inlet water

S

Rinsing liquid

AR

Wastewater disposal facility

A.W.

sewage

R

Time of adding cleaning agent

D

Difference between reference value and comparison value

Claims (12)

Dishwasher, in particular a household dishwasher, with a washing chamber (7) for receiving items to be washed, with a dosing device (26) for receiving cleaning agents and/or cleaning aids, with a control and/or regulating device (2) which is designed to operate the dishwasher (1) according to a washing program that can be selected from a plurality of washing programs and to at least partially open the dosing device (26) during the course of the respective washing program so that cleaning agents and/or cleaning aids reach the washing chamber (7), and with a sensor (25) for determining at least one characteristic of a washing liquid (S) circulating in the dishwasher (1), wherein the control and/or regulating device (2) is designed to determine the characteristic before opening the dosing device (26) in the form of at least one reference measurement and after opening the dosing device (26) in the form of at least one comparison measurement and to carry out the washing program on the basis of the difference (D) or another relation between the reference value determined during the reference measurement and the to select and/or modify the comparison value determined during the comparison measurement, wherein the control and/or regulating device (2) is designed to carry out the reference measurement immediately before opening the dosing device (26) and to carry out the comparison measurement after a defined period of time, in particular a period of time between 40 and 80 seconds, preferably a period of time between 50 and 70 seconds, after opening the dosing device (26). Dishwasher according to the preceding claim, characterized in that the sensor (25) is a sensor for measuring the turbidity, the pH value, the electrical conductivity, the viscosity and/or the density of the rinsing liquid (S). Dishwasher according to one or more of the preceding claims, characterized in that the control and/or regulating device (2) is designed to determine the time period on the basis of the amount of the reference value. Dishwasher according to one or more of the preceding claims, characterized in that the control and/or regulating device (2) is designed to select at least one alternative washing program and/or to modify the washing program if the difference (D) between the reference value and the comparison value is above a defined limit value. Dishwasher according to one or more of the preceding claims, characterized in that the control and/or regulating device (2) is designed to convert the difference (D) into a percentage deviation from the reference value and to select at least one alternative washing program and/or to modify the washing program if the deviation is above a defined limit value, for example above 10%, preferably above 15%. Dishwasher according to one or more of the preceding claims, characterized in that the control and/or regulating device (2) is designed to set the limit value as a function of the reference value. Dishwasher according to one or more of the preceding claims, characterized in that the control and/or regulating device (2) is designed to carry out a basic measurement of the characteristic variable at the beginning of the washing program and to set the limit value taking into account the base value determined with the aid of the basic measurement. Dishwasher according to one or more of the preceding claims, characterized in that the dishwasher (1) has a heating device (32) for heating the rinsing liquid (S) and a temperature sensor for determining the temperature of the rinsing liquid (S), and that the control and/or regulating device (2) is designed to set the limit value as a function of the temperature at a defined point in time of the rinsing program, in particular at the point in time of the reference and/or comparison measurement. Dishwasher according to one or more of the preceding claims, characterized in that the control and/or regulating device (2) is designed to record several measured values during the reference measurement and/or the comparison measurement and to calculate an averaged reference value and/or averaged comparison value from the measured values determined. Dishwasher according to one or more of the preceding claims, characterized in that the washing program comprises several washing cycles, e.g. in the form of a pre-wash cycle, a cleaning cycle, an intermediate rinse cycle, a final rinse cycle and/or a drying cycle and the control and/or regulating device (2) is designed to modify or skip individual rinse cycles depending on the reference value and the comparison value, in particular their difference (D). Dishwasher according to one or more of the preceding claims, characterized in that the dosing device (26) has a filling sensor (33) for checking whether or how much rinse aid is in the dosing device (26). Method for operating a dishwasher (1), in particular a household dishwasher (1), with a washing chamber (7) for receiving items to be washed, with a dosing device (26) for receiving cleaning agents and/or cleaning aids, such as rinse aid, wherein the dishwasher (1) is operated according to a washing program selected from a plurality of washing programs, wherein the dosing device (26) is opened at least partially during the washing program with the aid of a control and/or regulating device (2) so that cleaning agents and/or cleaning aids reach the washing chamber (7), and wherein at least one characteristic variable, in particular the turbidity, the pH value, the electrical conductivity, the viscosity and/or the density, of washing liquid (S) circulating in the dishwasher (1) is determined with the aid of at least one sensor (25), wherein the characteristic variable is determined with the aid of the control and/or regulating device (2) before the opening of the dosing device (26) in the form of at least one reference measurement and after the opening of the dosing device (26) in the form of at least one comparison measurement and the rinsing program is selected and/or modified depending on the difference (D) or another relation between the reference value determined during the reference measurement and the comparison value determined during the comparison measurement, wherein the reference measurement is carried out immediately before the opening of the dosing device (26) and the comparison measurement is carried out after a defined period of time, in particular a period of time between 40 and 80 seconds, preferably a period of time between 50 and 70 seconds, after the opening of the dosing device (26).

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