EP1362546B1 - Method of operating a dishwasher and dishwasher therefor - Google Patents

Description

The invention relates to a method for operating a dishwasher according to the preamble of claim 1 and a dishwasher, which is operated by the method according to the invention.

In a dishwasher Spülgutteile be cleaned by adhering debris. After setting soiled items in the dishwasher in designated recordings such. As baskets and cutlery baskets, a method for operating a dishwasher by the user is started. If a plurality of program sequences are provided for the operation of the dishwasher, then the user can generally be identified by selection means, as can be seen from DE 19 651 297 A, which can be seen, for example, in US Pat. B. are arranged in a control panel on the dishwasher, select a specific method. So z. B. methods under the name intensive program, short program, normal program and similar notions known. Known manner, a method comprises at least a plurality of liquid-conducting process sections, also called program sections, such as. B. pre-rinsing, cleaning, intermediate rinsing, rinsing, which are connected in sequence, and serve to clean the set in the dishwasher soiled items. In the pre-rinse process section, mainly a soak is more firmly adhered Dirt particles on the items to be washed and a mechanical cleaning of easily removable contaminants from the dishes instead. As a rule, no chemical washing substances are added in this process section to improve the pre-treatment result. In the process section cleaning, chemical washing substances are known to be added, wherein in this process section mainly the cleaning of the ware is carried out by its adhering dirt particles. In the intermediate rinsing step, residues of dirt particles and rinsing liquid residues are removed with residues of chemical washing substances from the cleaning process step. In a process section rinsing, on the one hand, residues of washing substances which have remained adhering to the items to be washed during the program section are to be rinsed off. On the other hand, in the process section rinse-clearing it is known to add a chemical substance known as rinse-aid, which reduces the surface tension of the water and thus enables a better dripping of the adhering rinsing liquid on the items to be washed. In the drying process section, the water adhering to the items to be washed and the residual moisture from the rinsing liquid-carrying process sections are removed.

EP 0 852 929 A2 discloses a method for operating a dishwasher, according to which the dishwasher is merely started at the start of the program and parameters to be set for the progress of the rinsing operation depend on at least one of the rinsing process which is necessary and influenced by it; adjusted parameters are set.

From DE 109 51 297 A1 a method for operating a dishwasher is known in which only at least one is predetermined by maximum and minimum values predetermined range of at least one necessary for the flushing process and influenced by him parameter. The at least one parameter to be set for the progress of the rinsing process is set in the preselected range limits as a function of at least one respectively detected parameter.

EP 0 553 803 B1 discloses a program sequence for cleaning freshly soiled items in a dishwashing machine, in which initially two pre-rinsing courses with cold rinsing liquid are followed directly by two rinses with hot rinsing liquid. This program sequence is compared to the above-described program sequences, in which between program sections with hotter, d. H. by intended heating means heated rinsing liquid, those with cold, d. H. Zuleitungstemperaturabhängiger, rinsing liquid are connected, from a purely energetic point of view in the advantage. Because between the individual program sections (pre-rinsing, pre-rinsing, cleaning, rinsing), where a complete rinsing fluid always takes place at the end of the program, the sequence of program sections energetically particularly favorable with respect to the program sections that cause hot rinse liquid designed. However, a disadvantage of this program sequence design is that in this washing program, the dishwasher is completely filled and emptied a total of four times, resulting in a high water consumption.

Based on this prior art, it is an object of the invention to propose a method for operating a dishwasher and a dishwasher, which operates according to the inventive method, in which the above-mentioned disadvantage is avoided, ie the consumption of rinsing liquid is lowered, and in the best possible energetic process management, a good cleaning result for different degrees of contamination of the dishes is guaranteed.

The above object is achieved by a method for operating a dishwasher according to the respective feature combination of claims 1-3 and by a dishwasher according to claim 15.

Advantageous embodiments of the invention are described in the subclaims.

According to the present invention, in a method for operating a dishwasher having a plurality of liquid-conducting process sections, but at least one pre-washing process section, at least one dilution step is provided in this process section pre-rinse. In this dilution step, the rinsing liquid initially used for pre-rinsing, which can be soiled to varying degrees, is replaced by the addition of fresh, ie. H. not soiled, rinsing liquid from storage vessels of the dishwasher and / or the water supply at least partially mixed with this. This results in a dilution of existing in the washing container of the dishwasher rinse liquid with respect to their degree of contamination. This is now circulated in the further course of the process section pre-rinsing in the dishwasher, the dilute rinsing liquid has a lower degree of contamination and thus a better cleaning power.

In order to limit the need for fresh rinse liquid as much as possible, ie to save extra water, In a particularly preferred embodiment, it is provided to pump off part of the already soiled rinsing liquid before and / or during the feeding of a fresh rinsing liquid volume.

The rinsing fluid volume, which is generally initially provided at the beginning of the program section for rinsing, amounts to approximately 4 l for a dishwasher with space for 12 normal place settings. Laboratory tests have shown that the cleaning result of the items to be cleaned is acceptable on average for all degrees of soiling, if the volume of the partly pumped dirty rinsing liquid advantageously by an equal volume of fresh, d. H. not soiled, rinsing liquid is replenished.

It can moreover be provided that, without a determination of the degree of soiling of the rinsing liquid which precedes the dilution step, the rinsing liquid volume is pumped off approximately halfway and replenished. Thus, dishwashers which are not equipped with a possibility for detecting the degree of turbidity, ie the degree of soiling of the rinsing liquid, are operated in a simple way to save water, being accepted that with increasing degree of contamination of the rinsing liquid, the cleaning result of the ware compared to that, the less dirty flushing fluid is applied, is slightly worse. Alternatively, even with the intended determination of the degree of turbidity of the rinsing liquid a basically half pumping and refilling of rinsing liquid is possible.

In a further particularly preferred embodiment, the duration of the program section prewash is set variably. This can be done for example by the erfirdungsgemäße user-related selection of the wash program depending on the degree of soiling of the set dishes, but also programmatically in response to various parameters that are recorded during the program or deposited in tables in a microprocessor control. With respect to a water supply with respect. A fixed monitoring levels of the liquid level in the dishwasher, which z. B. is set to a pump speed of 1,900 rpm of a circulating pump laboratory tests have shown that it makes sense in terms of good cleaning results that a process section pre-rinsing with a dilution step lasting at least longer than 10 minutes. For comparison, a conventional pre-rinse takes an average of 3 to 10 minutes.

In a further embodiment, the pre-rinsing process section can be terminated by a dilution step or by completely pumping out the rinse liquid used. The former means that a partial volume of the rinsing liquid is partially reused in the following program section cleaning, which is favorable in terms of the lowest possible water consumption. In the other case, a complete pumping out of the used rinsing liquid at the end of the pre-rinsing, which in particular at a high degree of contamination, z. B. by a large amount of dirt particles, in terms of a particularly good cleaning result makes sense. In one embodiment, which in particular for persistent contamination, z. B. as a result of prolonged drying of the dirt particles on items to be washed before the start of the dishwasher is suitable, thus can perform a plurality of dilution steps be provided during the process section pre-rinsing. As a result, on the one hand, the soaking time of the dirt particles on the dishes increases, on the other hand, the mechanical cleaning effect is extended.

It is of particular advantage for the improvement of the cleaning result and the reduction of the rinsing liquid volume used for pre-rinsing, if the number and / or the onset and / or duration of individual dilution steps and the determination of the case exchanged rinsing liquid volume during the pre-rinsing in dependence of determined measurement results or several turbidity measurements of the rinsing liquid during this process section. So z. B. at a particularly high degree of contamination of the dilution step during the pre-rinsing are repeated and this combined with a complete pumping at the end of the process section pre-rinsing, while at a low degree of contamination, a dilution step, preferably at the end of the process section pre-rinsing, sufficient to a particularly good To achieve cleaning result.

It is known that subsequent to the process section pre-rinsing further liquid-conducting process sections such as cleaning and rinsing with adding the characteristic chemical substances, it may be useful depending on the degree of contamination of the screen for the overall cleaning result, between the process sections cleaning and rinsing a process section for Switching screen cleaning, which is referred to below as "screen cleaning". For this purpose, at the end of the process section cleaning either a partial or complete emptying of the rinsing liquid used in this case takes place, this is in the sump either at least partially left and / or with fresh rinse liquid is replenished. The volume is dimensioned such that a one-piece or multi-part sieve arrangement present in the sump and covering it, in particular the covering sieve, is not completely covered by rinsing liquid. In a predetermined time, which can also be variably adjusted by the control device, the rinsing liquid remains there and is finally completely or partially pumped out. In order to achieve effective cleaning of the sieves, the rinsing liquid is not circulated during this process section, so that before rinsing the rinse liquid has roughly clogged dirt particles stuck in the sieve and now entrains during the pumping, this crushed and the fine sieve for filtering fed from the rinsing liquid. In order to save energy as much as possible during this process section, the supplied rinsing liquid is only passively heated, ie there is no energy of the rinsing liquid, eg. B. supplied by switching heating means provided, so that an increase in temperature of the rinsing liquid during this process section only as a result of the absorption of stored energy throughout the dishwasher. Such tempered rinsing liquid is referred to below as lukewarm.

In order to avoid in particular a complete removal of the stored energy in the dishwasher, the process section screen cleaning will last much shorter than the previous process stage cleaning or the subsequent process section rinse, because energetically it is particularly favorable residues of stored energy for heating the rinsing liquid in to use the following process section rinse. By interposing a procedure section Sieve cleaning but water-saving possibly a multiple repetition of a dilution step during a pre-washing process section can be avoided.

It is also of particular advantage if during the process section screen cleaning on the one hand, the volume of the rinsing liquid supplied is less than the respective maximum existing volume of rinsing liquid in the dishwasher during the process sections cleaning or rinsing, so that thereby the residence time of the rinsing liquid in the dishwasher and thus the possibility of energy extraction, as well as the total duration of this process section is minimized, which makes sense in terms of reducing the energy and water consumption, as already mentioned above.

It is furthermore of particular advantage if, in addition or as an alternative to screen cleaning between the cleaning and rinsing process sections, at least one additional liquid-conducting intermediate flushing process section is switched off for the purpose of completely removing the residues of chemical substances from the cleaning process section, which comprises at least one dilution step, preferably at the end of the process section Intermediate rinse, has. This is preferred for the following process section, for. As rinsing or screen cleaning, a partial volume of rinsing liquid used in each case the immediately preceding part of the process, so that the water consumption is kept low. Furthermore, the supplied rinsing liquid volume can in turn be heated passively during the dilution step, so that the energy consumption is kept as low as possible. The advantage that all adhering residues of chemicals and last dirt particles from the indirectly or immediately preceding process section Cleaning be removed during the intermediate purging is, with additional water consumption and an increased energy requirement in the subsequent to the intermediate rinse process section, the hot rinsing liquid leads, z. B. in rinsing, bought. Because the energy stored in the dishwasher for heating the supplied rinsing liquid is this inevitably removed during the intermediate rinsing and / or screen cleaning and is thus no longer or only partially available for heating the rinsing liquid during rinsing. Therefore, it is advantageous to provide this process section intermediate rinsing only for special needs, z. B. if by measuring the flushing liquid by appropriate sensors this is considered necessary.

In particular, it is particularly advantageous to determine the number and / or the time and / or the duration of the dilution steps in the cleaning, intermediate rinsing and rinsing process sections as well as the volume of the rinsing liquid to be pumped or returned as a function of the result of at least one turbidity measurement of the rinsing liquid while at least one of the individual process sections cleaning, intermediate rinsing, screen cleaning or rinsing is made variably adjustable.

It is also advantageous if this adjustment takes place as a function of the degree of contamination of the washing liquid by turbidity measurements during at least one of the individual process section, so that an optimization of the energy and water consumption is achieved.

With further advantage, the set wash ware is substantially cold during the process section Rinsing liquid acted upon, ie the rinsing liquid temperature is essentially dependent on the temperature of the water inlet and is not heated by connecting provided heating elements in the dishwasher. In contrast, the rinsing liquid is heated at least in the process sections cleaning and preferably also in the rinse by switching provided heating means. As an alternative to the above-described method description, these heating means can also be used at least partially for heating the rinsing liquid during the intermediate rinsing, so that hot rinsing liquid is also applied to the set items to be rinsed in this method section.

The design of the temperature profile is limited in a lower temperature range essentially by the temperature of the water, the inlet and in an upper region by the glass corrosion at about 65 ° C.

Without limiting the above-mentioned invention, the temperature profile can be variously designed so that the transitions from cold to lukewarm to hot are conducted through various intermediate levels of temperature.

Advantageously, a dishwasher is operated according to at least one of the methods described above. In a further embodiment of the dishwasher, at least one selection means for manual program selection can be provided by a method according to the invention, which enables the operation according to at least one of the proposed methods. The selection by the user can also be done indirectly by the degree of contamination of the set items, so that a suitable program selection is made as a function of at least one turbidity measurement.

The invention will be explained below with reference to a schematic program sequence according to an embodiment.

- Fig. 1

ein Schema eines Verfahrensablaufes mit den spülflüssigkeitsführenden Verfahrensabschnitten Vorspülen mit einem Verdünnungsschritt, Reinigen, Klarspülen;

- Fig. 2

ein Schema eines Verfahrensablaufes mit den flüssigkeitsführenden Verfahrensabschnitten Vorspülen mit zwei Verdünnungsschritten, Reinigen, Klarspülen;

- Fig. 3

ein schematischer Verfahrensablauf mit den Verfahrensabschnitten Vorspülen mit zwei Verdünnungsschritten, Reinigen, Siebreinigen, Klarspülen; und

- Fig. 4

ein Schema eines Verfahrensablaufes mit den flüssigkeitsführenden Verfahrensabschnitten Vorspülen mit einem Verdünnungsschritt, Reinigen, Zwischenspülen mit einem Verdünnungsschritt, Klarspülen

Showing:

- Fig. 1

a schematic of a process flow with the rinsing liquid-carrying process sections pre-rinsing with a dilution step, cleaning, rinsing;

- Fig. 2

a schematic of a process flow with the liquid-carrying process sections pre-wash with two dilution steps, cleaning, rinsing;

- Fig. 3

a schematic procedure with the process sections pre-rinsing with two dilution steps, cleaning, sieve cleaning, rinsing; and

- Fig. 4

a schematic of a process flow with the liquid-carrying process sections pre-rinsing with a dilution step, cleaning, intermediate rinsing with a dilution step, rinse

In Fig. 1 to 4 each wash programs for the operation of a domestic dishwasher for the purpose of cleaning set items are shown.

In Fig. 1, the time is not drawn to scale on the ordinate, while on the abscissa on the one hand the Spülflüssigkeitsvolumen and on the other hand, the temperature is not to scale is applied. These axis designations are also valid for FIGS. 2 to 4. Curve A shows the course of the volume of rinsing liquid in the washing container of the dishwasher. For the time course of this curve A, the temperature profile of the rinsing liquid over the time, which is shown in curve B corresponds. This is essentially determined by the temperature of the rinsing liquid as a result of heating by switching on provided heating means, temperature changes due to absorption and release of stored energy with the environment or the heat capacity of the dishwasher are only tended to take into account. At the time t ₀ , the start of the wash program, rinse liquid is first fed to a rinse tank until a predetermined volume of about 4 1 is reached at time t ₁ . This rinsing liquid volume is circulated in the dishwasher at a temperature which essentially corresponds to the feed temperature of the water, ie, it is pressed from a sump via a feed line into spray arms and from there is charged with the ware. At a time t ₂ , which can be selected arbitrarily during the pre-rinsing, the partial pumping of the rinsing liquid volume and thus a dilution step begins. The rinsing liquid volume is reduced in half at a time t ₃ , the end of the pumping down, and is refilled from a time t ₄ back to the originally maximum rinsing liquid volume, this state being reached at a time t ₅ . The time intervals t ₃ to t ₄ (as well as t ₇ to t ₈ and t ₁₁ to t ₁₂ ) are with respect to the rinse fluid in the rinse container dead times that arise through the inlet path of the water or the filling of storage vessels outside of the rinse with water.

In the rinse tank is from the time t ₅ now contaminated rinse liquid, which has been blended with fresh rinse liquid in the period t ₄ to t ₅ and by their dilution has an increased dirt holding capacity, which is conducive to the cleaning result. After the dilution step, a volume of approx. 4 l of rinsing liquid is again available in the dishwasher for circulation. After the dilution step, which lasts from t ₂ to t ₅ , in the period t ₅ to t _6, the pre-rinsing is continued for a certain period until it starts with the complete pumping out of the rinsing liquid, which begins at a time t ₆ and stops at t ₇ , finished. The temperature profile of the rinsing liquid during the pre-rinsing mainly depends only on the water temperature of the supply line and is almost constant. After the end of the pre-rinsing at time t ₇ and an almost rinsing liquid-free time t ₇ to t _{8 of} the rinse, after a dead time t ₇ to t ₈ again fresh rinse liquid with a maximum volume of about 4 l in the bottom of the dishwasher in the period t ₈ to t ₉ for the process section cleaning supplied. This rinsing liquid is heated by the water inlet temperature to about 45 to 55 ° C. The process section cleaning is terminated by a complete pumping, which by pumping out the heated rinsing liquid in a period t ₁₀ to t ₁₁ an energy sales of the entire system and re-filling with fresh rinse liquid in a section t ₁₂ to t ₁₃ , the energy losses of the entire system must be compensated for the subsequent rinsing by energy. However, the temperature of the rinsing liquid does not decrease to the supply line temperature, since in the part of the rinsing liquid volume, storage vessels have been removed in which the rinsing liquid has already been passively heated. The heated to about 55 to 65 ° C Rinsing liquid in the process section rinsing is also circulated in the period t ₁₃ to t ₁₄ . At a time t ₁₄ , the pumping starts and at a time t ₁₅ , the used rinsing liquid is removed from the dishwasher. A non-rinsing liquid-carrying process section drying, which is not shown here, can follow the liquid-conducting process sections. The duration of the pre-rinsing is about 10 to 15 minutes, preferably 12 minutes, but may vary between about 10 to 20 minutes, this process section should last significantly longer than conventional pre-rinsing programs, which have a duration of about 4 to 5 minutes. The duration of the process section cleaning can be between 20 and 60 minutes and in the exemplary embodiment is preferably about 50 minutes. The duration of the process section rinsing varies depending on reaching the maximum intended rinse temperature between 10 and 25 min. The duration of the cleaning and rinsing process sections is limited upwards at least by the desired total duration of the rinsing program or by a desired maximum energy consumption. Since no energy has to be provided for heating the rinsing liquid for the duration of the pre-rinsing, the duration of the pre-rinsing is almost arbitrary from an energy point of view, but it is limited by a desired total duration of the rinsing program.

Fig. 2 shows a schematic course of a pre-rinse containing two dilution steps, wherein the scheme of the liquid volume of the curve A and the temperature profile of the curve B, as described in Fig. 1, wherein the pre-rinse of t ₀ to t ₆ analogous to 1, and after a first dilution step in the time interval t ₂ to t ₅ with the second dilution step in the time period t ₆ to t _{9 is ended} at t ₈ , wherein the end of the second dilution step (t ₈ to t ₉ ) passes into the cleaning section and thereby a partial volume of the rinsing liquid of the pre-rinsing is diluted again and in the following process section cleaning in the period t ₈ to t ₁₁ is used. The process section cleaning is terminated by a complete pumping out of the rinsing liquid in the time interval t ₁₀ to t ₁₁ at the time t ₁₁ . After repeated filling of the rinsing liquid analogous to FIG. 1 in the time interval t ₁₂ to t ₁₃ , approximately 4 l rinsing liquid is present in the dishwasher for the rinsing at the time t ₁₃ and is heated to approximately 55 to 60 ° C. By completely pumping out the flushing liquid used at that time, which begins at time t ₁₄ and ends at time t ₁₅ , essentially only rinsing liquid adhering to the items to be washed and washing container is present in the dishwasher, which is removed by subsequent drying, but not shown here ,

As a result of the fact that the pre-rinsing process section passes through a dilution step into the cleaning process step, the water consumption is further reduced compared to the program sequence according to FIG. 1.

FIG. 3 shows a prewash followed by a cleaning analogous to FIG. 2 in the time interval t ₀ to t ₁₁ . After complete emptying of the rinsing liquid at the time t ₁₁ , an interposition of a process section for sieve cleaning takes place in the time interval t ₁₂ to t ₁₅ . In this case, rinsing liquid is fed to the sump of the dishwasher in the period t ₁₂ to t ₁₃ , without causing an active heating of the rinsing liquid by connecting provided heating medium. The filling of the volume of the rinsing liquid is significantly lower than the maximum volume present in the rinsing container during the pre-rinsing, Cleaning and rinsing, and carried out until it reaches the level of the top sieve. After a dwell time t ₁₃ to t _{14 of} the maximum rinsing liquid present in this process section in the sump, wherein the dwell time is preferably less than 2 min and also significantly shorter than in the individual process sections pre-rinsing, cleaning and rinsing, the rinsing liquid is completely in the time t ₁₄ to t ₁₅ pumped. As a result of the increase in the liquid level to the upper sieve in the time interval t ₁₂ to t ₁₃ , dirt particles are suspended or those which have remained suspended in the sieve are entrained during pumping (t ₁₄ to t ₁₅ ). During the program section sieve cleaning, the circulating pump in the period t ₁₂ to t _{15 is} not in operation, so that the items to be washed is not charged with rinsing liquid, and rinse residues of items to wash the spray arm and in particular from the ceiling and the walls of the washing. The process section screen cleaning is followed at time t _16, a new filling of the sump with rinsing liquid to about 4 1, which is reheated and circulated in the washing during rinsing. The temperature profile is similar to the end of the section cleaning those of Figs. 1 and 2 and increases due to the consumption of stored energy during the exclusively passive heating in the period t ₁₂ to t ₁₅ during the program section screen cleaning in the subsequent program section rinse in the period t ₁₆ to t ₁₇ somewhat flatter than in the corresponding time intervals t ₁₂ to t ₁₃ of Fig. 1, 2, so that to achieve an energy label A certification respect. At the time of the invention prescribed there maximum predetermined consumption of 1.05 kWh in total within a normal rinsing program during the rinsing liquid-carrying program sections of the cleaning and rinsing process section be designed significantly shorter must than in the programs of Fig. 1 and 2, if the same maximum temperatures in the cleaning and rinsing should be achieved.

4 shows a schematic program sequence with successive program sections pre-rinsing with a dilution step, cleaning, intermediate rinsing with a dilution step, rinsing with rinse. Here, the pre-rinse and the cleaning section are designed analogously to FIG. 1 in the time interval t ₀ to t ₁₁ . After pumping the rinsing liquid in the time period used in the process section cleaning t ₁₀ to t ₁₁ to time t ₁₂ again rinsing the sump of the dishwasher supplied, which is in the time interval t ₁₂ to t ₁₅ in the washing passively heated. After a partial emptying in the period t ₁₄ to t ₁₅ at the end of this process section takes place in the transition to the process section rinsing a new filling of the rinsing liquid in the period t ₁₆ to t ₁₇ , so that after a renewed dilution step in the period t ₁₄ to t ₁₇ a partial volume during rinse liquid used in the intermediate rinse is reused in the following rinse cycle, which is diluted with fresh rinse liquid. The dilution step is shown in phantom as an alternative, whether it is performed can be determined by at least one result of turbidity measurement. From an energetic point of view for achieving energy label A certification, the program section intermediate rinsing shortens the duration of the program sections cleaning and rinsing, since on the one hand the dishwasher supplied energy during the program section cleaning with the completely pumped rinsing liquid at the end of this process section is lost to the system of the dishwasher and the stored energy for passive heating of the rinsing liquid in the intermediate rinsing process section is almost used up becomes. With the partial emptying at the end of the process section intermediate rinsing energy supplied to the system during the program section cleaning continues to be lost. The freshly supplied partial volume of rinsing liquid must be reheated during rinsing. In the temperature curve in curve B, the transition of the dilution step between the intermediate rinsing and rinsing is shown in dashed lines and compared in the same curve an energy profile without dilution step, which is shown fully extended. From this it can be seen that, from an energetic point of view, an additional dilution step and an intervening passively heated process section intermediate flushing between two process sections with hot flushing liquid is unfavorable. Because the dissipated and the heat capacity of the dishwasher removed energy during the intermediate flushing missing in the second process section rinse for heating the rinsing liquid and must be supplied. The process management with intermediate rinses and additional dilution steps is thus a compromise to achieve an improved washing result while energy and water consumption are better coordinated. Intermediate rinsing prevents chemical residues from the program section cleaning, the dilution steps reduce the water consumption compared to complete water changes. In order to also take into account the respective currently existing degree of soiling of the rinsing liquid, which can be greatly different, the volume of rinsing liquid to be pumped off and replenished is determined as a function of the result of at least one turbidity measurement of the rinsing liquid. In the case of low turbidity, alternatively one or all dilution steps can be dispensed with. Due to the reduced water consumption then decreases the energy consumption in otherwise same process parameters. The duration of the intermediate rinsing and clear rinsing is in particular dependent on the performance of a dilution step between about 10 to 35 min.

Without limiting the invention, it is conceivable to carry out the dilution steps at least without prior pumping of a partial volume, so that more than about 4 l of rinsing liquid is in the dishwasher in the short term. Furthermore, the number of dilution steps in each liquid-carrying process section is variable, especially between two process sections that carry hot rinse liquid, a dilution step is more energetic and in terms of water consumption more favorable than a complete draining and replenishment with rinsing liquid, but may suffer from the cleaning result, so that in Depending on at least one turbidity measurement during the process section cleaning the further process flow to optimize the energy and water consumption can be designed with an acceptable wash result. If the process sections cleaning and rinsing with respect to the achievement of an energy label A certification at the above maximum temperatures during the individual process sections are provided correspondingly short, may be connected between them in addition to an intermediate rinsing and a program section for screen cleaning. The sequence of program sections sieve cleaning and intermediate rinsing can be reversed, in the case of the presence of very large impurities, these program sections can be repeated in whole or in part in different succession. Furthermore, pulse rinsing is possible at least in the program section intermediate rinsing. The use of 3inl combination preparations is possible. Concurrent applications P-10073, title "Method of operating a dishwasher" of 16.05.2002 and P-10078, title "Dishwasher and method for operating a dishwasher when using a combination preparation with multiple active ingredients" dated 16.05.2002 is made to adapt the program design of this application.

Claims (16)

1. Method of operating a dishwasher for the purpose of cleaning articles disposed therein, the method comprising plural liquid-conducting cycles, at least one liquid-conducting cycle being a pre-rinse, in which case during the pre-rinse cycle at least one dilution stage is provided, in which fresh washing liquid is added to a dirty volume of washing liquid, characterised in that the user selects the washing programme according to the degree of dirtiness of the tableware placed in the dishwasher, wherein

   - plural dilution stages are carried out during the pre-rinse cycle and the pre-rinse cycle ends with a dilution stage or

   - the pre-rinse cycle ends with a dilution stage.
2. Method of operating a dishwasher for the purpose of cleaning articles disposed therein, the method comprising plural liquid-conducting cycles, at least one liquid-conducting cycle being a pre-rinse, in which case during the pre-rinse cycle at least one dilution stage is provided, in which fresh washing liquid is added to a dirty volume of washing liquid, in particular according to claim 1, characterised in that the user selects the washing programme according to the degree of dirtiness of the tableware placed in the dishwasher, in which case before and/or during the addition of fresh washing liquid a partial volume of dirty washing liquid is pumped out, the volume of washing liquid which is exchanged in the dilution stages being determined according to the measurement results of one or more cloudiness measurements of the washing liquid, and in that plural dilution stages are carried out during the pre-rinse cycle, the number and/or duration and/or moment of the dilution stages provided being set in a variable manner according to measurement results of the cloudiness of the washing liquid during the pre-rinse cycle.
3. Method of operating a dishwasher for the purpose of cleaning articles disposed therein, the method comprising plural liquid-conducting cycles, at least one liquid-conducting cycle being a pre-rinse, in which case during the pre-rinse cycle at least one dilution stage is provided, in which fresh washing liquid is added to a dirty volume of washing liquid, in particular according to claim 1 or 2, characterised in that the user selects the washing programme according to the degree of dirtiness of the tableware placed in the dishwasher, and in that at least one further liquid-conducting cycle is provided between the cleaning and final rinse cycles, preferably a filter-cleaning cycle and/or intermediate rinse, in which case after partial evacuation of the washing liquid at the end of the cleaning cycle, washing liquid is added.
4. Method of operating a dishwasher according to one of claims 1 or 3, characterised in that during the pre-rinse cycle, at least one dilution stage is provided, in which fresh washing liquid is added to a volume of dirty washing liquid, the washing programme running in a programme-controlled manner according to various measuring parameters which are stored in tables in a microprocessor of a control device.
5. Method of operating a dishwasher according to one of claims 1 to 4, characterised in that before and/or during the supply of fresh washing liquid, a partial volume of dirty washing liquid is pumped out.
6. Method of operating a dishwasher according to one of claims 1 to 5, characterised in that the volume of washing liquid which is added during the dilution stage in the pre-rinse cycle is exactly equal to the volume of washing liquid which has previously been partially pumped out and/or is being pumped out simultaneously.
7. Method of operating a dishwasher according to at least one of the preceding claims, characterised in that the pre-rinse cycle duration is set in a variable manner and/or lasts at least longer than 12 minutes.
8. Method of operating a dishwasher, in particular according to at least one of claims 1 to 7, characterised in that at least one further liquid-conducting cycle is provided between the cleaning and final rinse cycles, preferably a filter-cleaning and/or intermediate rinse cycle, in which case after partial evacuation of the washing liquid at the end of the cleaning cycle, washing liquid is added.
9. Method of operating a dishwasher according to claim 8, characterised in that in the filter-cleaning cycle the washing liquid is not circulated while it remains in the dishwasher and, after a variably or fixedly adjustable dwell time, is pumped out completely or partially before the subsequent cycle.
10. Method of operating a dishwasher according to claim 8 or 9, characterised in that the cleaning and final rinse cycles last longer than the filter-cleaning cycle.
11. Method of operating a dishwasher according to at least one of claims 8 to 10, characterised in that in the filter-cleaning cycle the volume of washing liquid added is smaller than the respective maximum available volume of the washing liquid in the dishwasher during the cleaning and/or final rinse cycle.
12. Method of operating a dishwasher according to at least one of claims 8 to 11, characterised in that between the liquid-conducting cleaning and final rinse cycles, two additional liquid-conducting cycles, namely filter-cleaning and intermediate rinse are added, at least one of these cycles comprising a dilution stage, preferably at the end of the cycle.
13. Method of operating a dishwasher according to claim 12, characterised in that the number and/or moment and/or duration of the dilution stages is variably adjusted at least in one of the cycles including cleaning, filter-cleaning, intermediate rinse and final rinse and/or the volume of the washing liquid to be pumped out and refilled is variably adjusted according to the result of at least one cloudiness measurement of the washing liquid at least during one of the respective cycles including cleaning, intermediate rinse or final rinse.
14. Method of operating a dishwasher according to at least one of the preceding claims, characterised in that during the pre-rinse cycle the articles placed in the dishwasher are sprayed substantially with cold washing liquid, in the intermediate rinse cycle with lukewarm washing liquid, and in the cleaning and final rinse cycle substantially with hot washing liquid.
15. Dishwasher which may be operated with a method according to at least one of claims 1 to 14.
16. Dishwasher according to claim 15, characterised in that at least one means is provided for the manual selection of a method of operating the dishwasher by the user.

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