Abstract:
In a method and an apparatus for operation of a dishwasher, a total maximum electric output is assigned to a group of electric consumer elements of the dishwasher. In addition, at least two output levels are assigned to each electric consumer element of said group. An optimum combination of output levels is then selected in a requirement determination step, based on an operational state B of the dishwasher, whereby for each consumer element the selected output level is adapted to the output requirement of the consumer element in operational state B and the total output of all consumer elements does not exceed the maximum electric total output. The output levels of the individual consumer elements are optimally adapted in accordance with the requirements in operating phases of the dishwasher, thus allowing a response to be made to any fluctuations in the operational state.

Description:
FIELD OF THE INVENTION 
     The invention relates to a method and an arrangement by means of which dishwashers can be operated with more energy being saved. One particular aim of the invention is to allow energy-saving operation of multiple tank dishwashers with washing zones, a rinsing zone and a drying zone. 
     PRIOR ART 
     Known machines, such as the dishwashing and drying installation described in DE 44 36 359 C2, typically have heaters installed for the individual loads, that is to say for the individual zones. These heaters are sufficient to cover the respective worst-case power demand. The worst-case power demand is in this case that amount of power which is required for the rated power of the machine. 
     The heating power levels in the individual zones differ, depending on the method being used. The installed heating power levels are in each case switched on and off depending on the instantaneous power demand. The addition of the heating power levels which are required for the rated power in each case results in the maximum connection level. 
     By way of example,  FIG. 1  illustrates a multiple tank dishwasher  110  corresponding to the prior art. In these dishwashers, the item  9  being washed is passed to a transport device  11  in the inlet  1 , and is then transported in the direction  10  through zones of precleaning  2 , main cleaning  3 , pump rinsing  4 , fresh-water rinsing  5 , heat recovery  6 , dry zone  7  and the outlet  8 . 
     Once the machine  110  has been switched on, the respective cleaner solution in the tanks  13 ,  17 ,  21  is provided in the zones  2 ,  3 ,  4  and is raised to the operating temperature by means of heaters  14 ,  18 ,  22 . The machine is ready to operate once respectively preset nominal-value temperatures have been reached in the tanks  13 ,  17 ,  21 . 
     The transport can then be switched on, with the item  9  being washed being placed on the transport device  11 , and then being transported through the zones  1  to  8 . During this process, the item  9  being washed has appropriate cleaning solutions applied to it via pumps  15 ,  19 ,  23  and via the washing systems  16 ,  20 ,  24 , and is cleaned. 
     The item  9  being washed has fresh water applied to it via a spraying system  28  in the fresh-water rinsing  5 , with this fresh water previously having been heated via a heat exchanger  29  and a heating element  26 . Residues of the cleaning solutions are washed away during this process. Fresh water is preheated in the heat exchanger  29  by means of hot exhaust air  31  from the dishwasher  110 . The fresh water is then heated further in a heating element  26 , in order then to be supplied to the spraying system  28 . 
     After being rinsed in the zone  5 , the item  9  being washed then has hot air  34  applied to it in the dry zone  7  via a fan  32  and a heater  33 , and is thus dried. The cleaned, rinsed and dried item  9  being washed is then removed in the outlet  8  of the dishwasher  110 . 
     By way of example, Table 1 lists typical power levels of loads in the illustrated machine  110 . In this case, only the power levels of the heating elements  14 ,  18 ,  22 ,  26  and  33  are listed, for simplicity. This simplified example ignores the power levels required for the pumps  15 ,  19  and  23  used for the spraying systems  16 ,  20  and  24 , as well as the drive power required for driving the transport device  11 , the exhaust-air fan  30 , the fan in the dry zone  32  and further loads that are not illustrated. The connection level for the heating elements in this example corresponding to the prior art results in a total power of 47 kW. 
     Only the heaters  14 ,  18  and  22  are typically switched on in the phase of heating the tanks  13 ,  17  and  21 . This results in a power level in the heating-up phase (starting phase) of 12+9+3=24 kW. The heating elements  26  and  33  are in this case typically not switched on. This 24 kW results in a typical heating-up time for the tanks  13 ,  17  and  21  and thus a specific predetermined time before the dishwasher  110  is ready to operate. 
     During the operating phase, the heaters  26  and  33  are then additionally switched on, with an additional heating power of 18 and 9 kW, respectively, in order to heat the fresh water and the drying air. In this operating phase, all of the heating elements  14 ,  18 ,  22 ,  26  and  33  are then switched on and off depending on whether the respective predetermined nominal temperatures have or have not been reached in these zones. If the predetermined nominal temperatures have not been reached, only the installed power levels are in each case available for subsequent heating. The heating powers of the heating elements  14 ,  18 ,  22 ,  26  and  33  are typically switched on and off at different times. 
     Dishwashers of the described type have numerous disadvantages which generally result from the operation of dishwashers such as these being very inefficient in terms of energy use. These disadvantages are thus associated in particular with the fact that the amount of electrical power supplied must not exceed a predetermined maximum value. This maximum value governs, in particular, the design of the electrical supply cables and the electronics. The individual loads in the dishwasher are generally matched to the respective demand independently of one another, so that all of the loads are operated at the maximum power in the worst case. Loads are in this case typically operated in such a way that they are either switched off or switched on at a predetermined power level. The maximum value of the total supplied power must therefore be matched to this “worst case”, in which all the loads are operated at the maximum power level. 
     Furthermore, dishwashers of the described type are frequently found to be very slow and cumbersome, particularly in the starting phase before they are ready to operate. This is particularly due to the fact that critical heating elements which, for example, are intended to control the operating temperature being reached in the tanks  13 ,  17  and  21  can be operated only at a respectively predetermined maximum power resulting from the abovementioned “worst case” scenario. 
     OBJECT OF THE INVENTION 
     The object of the invention is thus to specify a method and an arrangement by means of which dishwashers can be designed such that more energy is saved and they are more flexible. 
     DESCRIPTION OF THE INVENTION 
     This object is achieved by the invention with the features of the independent claims. Advantageous developments are described in the dependent claims. 
     A method is proposed for energy-saving operation of a dishwasher, in particular for washing dishes or medical appliances, as well as an apparatus for in each case carrying out the method in one of the described refinements. The dishwasher may, in particular, be a multiple tank dishwasher. The method steps described in the following text need not necessarily be carried out in the described sequence. Further method steps, which are not included, may also be carried out. Reference is made to  FIG. 2  for the numbering of the method steps. 
     The dishwasher should have a total number N≧2 of electrical load elements. As already described above, these load elements may, for example, be heating elements, pump elements, fans or drive elements. Further load elements may also be included, for example power supplies for controllers or computers. 
     In this case, a group of n electrical load elements is assigned a maximum electrical total power p max  (step  210  in  FIG. 2 ), where n is a natural number and n&gt;1. Furthermore, n should be less than or equal to the total number N of electrical load elements in the dishwasher: n≦N. All or else only some of the load elements in the dishwasher can thus also be included in the method. 
     Furthermore, each electrical load element i in the group of n electrical load elements is assigned a finite number m i  of discrete electrical power levels p ij  (step  220  in  FIG. 2 ). In this case, m i  should assume at least the value 2. The first index i of the discrete electrical power levels p ij  is a natural number which successively numbers the electrical load elements, and in which case iε{1, . . . , n}. The individual power levels for a specific load i are numbered successively by the second index j. In this case, j is likewise a natural number, which is greater than zero and can assume the maximum value m i : 0&lt;j≦m i . 
     A maximum power level p imax  is assigned to each load element i, so that p ij  can assume at most the value p imax  for all i, j. The sum of all the maximum power levels p imax  forms a so-called “worst-case total power” p worst . In this case, the maximum electrical total power p max  should be less than the worst-case total power p worst . In contrast to the prior art, in which p worst  is typically shared directly between the individual load elements, this condition ensures that the total power demand of the dishwasher is reduced. 
     Furthermore, each load element i is assigned a so-called “regular power level” p ireg , which is between zero and the respective maximum power level p imax . These regular power levels are in fact chosen such that the sum of the regular power levels p ireg  over all the load elements i is just equal to the maximum electrical total power p max . The maximum electrical total power is thus “shared” between the individual load elements i. 
     Furthermore, a so-called “demand determination step” is carried out (step  230  in  FIG. 2 ). In this case, an optimum combination of power levels p ij (B) is selected depending on the operating state B of the dishwasher, with the selected power level p ij (B) for each load element i being matched to the power demand of the load i in the operating state B. 
     By way of example, an operating state is in this case characterized by an operating phase in which the dishwasher is actually being operated (for example the starting phase, switched-on phase, load regulation phase) or, for example additionally, by corresponding operating parameters or operating state variables, for example by means of measured values of specific sensors in the dishwasher (for example temperature sensors, flow sensors, pressure sensors). By way of example, each operating state B can thus be characterized by an operating state variable F and/or by a plurality of operating state variables, in which case the operating phase variable F may assume at least three discrete values F 1 , F 2 , F 3 . In this case, F 1  denotes a starting phase of operation of the dishwasher, F 2  a switched-on phase of operation of the dishwasher, and F 3  a load regulation phase of operation of the dishwasher. 
     By way of example, in the demand determination step, more power can be supplied to specific heating elements in a starting phase than in a subsequent operating phase. Furthermore, the power levels p ij (B) are selected such that the sum of all the power levels p ij (B) assumes at most the value p max . Ideally, the method is in this case carried out such that this sum just reaches the value p max  again, or is only slightly less than it, so that the total available power is optimally used. This ensures that, as in the case of the prior art as well, each heating element is operated with its maximum permissible power, when required. 
     In contrast to the prior art, however, other load elements for which there is little requirement at that time have correspondingly less power applied to them in this case. The power is thus distributed, controlled by the respective demand, in accordance with the discrete power levels p ij  of the individual load elements, in which case the total sum of the power levels is in each case as high as possible, and the greatest possible power is applied at any given instant to the heaviest required load. In this case, priorities can also be preset, that is to say by way of example that the maximum possible power should initially be allocated to specific heating elements in the dishwasher, in particular specific heating elements which heat water in one or more water tanks and/or water circuits, before power is applied to other elements with a lower priority. 
     In practice, the demand-dependent allocation of electrical power levels can be carried out, for example, by using a computer for control purposes. By way of example, specific scenarios (operating states, value ranges of operating state variables) can be stored in an electronic memory, for example in an electronic table or look-up table. Each possible scenario or operating state B can be allocated an optimum set of power levels simply by reading the electronic table, so that the sum of these allocated power levels as far as possible reaches the maximum permissible total power p max , or is below it only to the least possible extent. 
     The fixed power levels can in practice be achieved, for example, by providing fixed power levels in the individual electrical supplies to the individual load elements themselves, between which it is just necessary to switch. For example, specific voltage dividers with fixed predetermined divider stages can be used. There is then no need for complex and expensive analog regulators. Alternatively and/or additionally, a software solution could also be used, or analog power regulators. 
     In practice, it has been found to be particularly advantageous to also be able to use a power level zero, that is to say when a power level for each load element exists for which no electrical power is applied to that load element. Furthermore, it is advantageous for three and only three power levels to be provided for each load element, in particular zero, p ireg  and p imax . This simple refinement can be implemented particularly easily in the circuitry and in its own right has all of the advantages of the invention. 
     Once the optimum combination of power levels has been determined in this way for the respective operating state, each load i has the respective power determined for it applied to it (step  240  in  FIG. 2 ). In this case, it should be noted that the allocation of the power in practice highly probably never corresponds completely exactly to the respective nominal value for example because technical tolerances (for example tolerances in electronic components) can result in minor discrepancies. However, the discrepancies in the power levels which are actually applied to the loads from the respective nominal value are advantageously no more than 10%, and preferably even no more than 5%. 
     The described method, in which the maximum electrical supplied power is governed not by the sum of the maximum individual power levels but by the sum of the “normal” power levels, offers a number of advantages over conventional methods. In particular, the described method typically makes it possible to save 20-30% of the power, which is actually financially significant in large concerns. 
     Furthermore, the described method also in some cases has a considerable influence on the functionality of the dishwasher. For example, the described method can be used to considerably shorten, in particular, the starting phase or heating-up phase, that is to say the phase between the dishwasher being brought into use and it actually being ready to operate. This not only results in better user friendliness, but in turn also reduces the total energy demand since the starting phase cannot be used in a financially worthwhile manner despite the demand for electrical energy. 
     The method described above can be extended by a number of advantageous refinements, with the aim of always observing the relationships described above between the individual characteristic variables, in particular between the various power levels of the individual load elements. This means in particular that the total sum of the assigned power levels for the individual loads should not exceed the maximum permissible total power p max . 
     In one advantageous refinement of the invention, the dishwasher is thus started first of all, thus marking a starting phase. At least one temperature of at least one washing liquid, in particular a temperature of water in at least one water tank and/or water circuit, is then detected. In particular, this may be done by means of one or more temperature sensors. 
     The at least one washing liquid is then heated by means of at least one heating element, with the respective heating element being used for heating purposes (which represents the load element l where lε{1, . . . , n}) being operated at the maximum power level p imax  associated with this heating element. The maximum possible electrical power is thus initially supplied to the heating elements that are required for the starting phase. However, in order to ensure that the total sum of the individual power levels of the load elements does not exceed the maximum permissible total power p max , the power for at least one further load element, which is not required to such a major extent in the starting phase, must be reduced appropriately. At least one load element q, which is not the same as the heating element l, where qε{1, . . . , n} and q≠1 is thus operated at a lower power level than the regular power level p qreg  associated with this load element q. By way of example, this may be the power level p qreg =0, that is to say the load element which is required to a lesser extent is completely switched off. 
     As soon as the at least one temperature of the at least one washing liquid reaches or has exceeded a predetermined nominal value, a switched-on phase is then started. In this switched-on phase, the power of all the load elements i is then initially set to the respectively associated regular power level p ireg . 
     As a result, for example, of various disturbances or environmental influences, it is, however, possible for disturbances to occur during operation of the dishwasher, in the event of which, for example, specific temperatures in various areas fall below a predetermined nominal value. In one advantageous development, at least one operating state variable is thus detected, in which case, as already mentioned above, this may by way of example be the measured values from various sensors. 
     A nominal value is allocated to at least one operating state variable. This may, for example, be preset nominal values, for example nominal values stored in a data memory or in an electronic table, or else nominal values which can be influenced by a user. By way of example, a user can thus vary specific nominal presets during operation of the machine, for example the temperature in specific areas of the machine, thus making it possible to influence the operation of the dishwasher. 
     If it is found (for example by means of a simple comparator) that the value of the at least one operating state variable differs by more than a predetermined tolerance from the respectively associated nominal value, a load regulation phase is started. This load regulation phase may, for example, be designed such that at least one load element r where rε{1, . . . , n} which influences the corresponding incorrect operating state variable is operated at a power level other than the regular power level p rreg . 
     By way of example, if it is found that the temperature in a liquid tank is excessively low, it is thus possible to temporarily operate a heating element which heats the liquid in this tank at an increased power level, for example at the maximum associated power p imax . As described above, the power of at least one further load element must, of course, be reduced in this case in order to ensure that the total sum of the power levels does not exceed the maximum total power p max . Once again, this allocation of power levels can be carried out, for example, by an appropriate set of power levels for this scenario being stored in an electronic table. 
     This load regulation operation is continued until the at least one operating state variable once again assumes a value which differs by not more than the predetermined tolerance from its nominal value. 
     Furthermore, the scope of the invention covers a computer program which carries out one of the embodiments of the method according to the invention when run on a computer or computer network. 
     The scope of the invention also covers a computer program with program-code means in order to carry out one of the refinements of the method according to the invention when the program is run on a computer or a computer network. In particular, the program-code means may be stored on a computer-legible data storage medium. 
     Further details and features of the invention will become evident from the following description of preferred exemplary embodiments in conjunction with the dependent claims. In this case, the respective features can be implemented in their own right or in groups of two or more combined with one another. The invention is not restricted to the exemplary embodiments. 
    
    
     
       The exemplary embodiments are illustrated schematically in the figures. The same reference numbers in the individual figures in this case denote identical or functionally identical elements, or elements whose functions correspond to one another. In detail: 
         FIG. 1  shows a belt transport dishwasher corresponding to the prior art; 
         FIG. 2  shows a flowchart of one simple refinement of the method according to the invention; 
         FIG. 3  shows a schematic arrangement for carrying out the described method with a belt transport dishwasher; and 
         FIG. 4  shows a schematic arrangement relating to the described method being carried out with a single-chamber dishwasher. 
     
    
    
       FIG. 3  illustrates one preferred arrangement, by means of which the method as described above can be carried out. The apparatus has a continuous-flow dishwasher, specifically a belt transport dishwasher, analogous to the dishwasher  110  illustrated in  FIG. 1 . The illustrated elements correspond to the respective elements of the dishwasher  110  in  FIG. 1 , and their functions are the same as them. Alternatively, further types of dishwashers could also be used. In addition, the arrangement in  FIG. 3  has a computer system with a central processor unit  312  and a data memory  314  (for example a volatile or non-volatile memory). The computer system  310  is connected via a main controller  316  to the dishwasher  110 , so that all of the major functions of the dishwasher can be controlled via the computer system  310 . 
     Furthermore, the apparatus illustrated in  FIG. 3  has a plurality of temperature sensors  318 , which can detect the temperature in the liquid tanks  13 ,  17  and  21  as well as in the air flow  34  of the fan  32 , as well as at various points in the liquid system  28  for the fresh-water rinsing  28 . Further temperature sensors as well as additional sensors, for example for pressure or flow rate, can be fitted at various points in the system. The data measured by the temperature sensors  318  is detected by means of a central measured-data detection unit  320 , is digitized and is made available to the computer system  310 . 
     Furthermore, in this exemplary embodiment, the system has five electrical power supplies  322 ,  324 ,  326 ,  328  and  330 , which supply electrical power to the heating elements  14 ,  18 ,  22 ,  26  and  33 . The electrical power supplies  322 ,  324 ,  326 ,  328  and  330  are each connected to respective externally controllable electrical power regulators  332 ,  334 ,  336 ,  338  and  340 . These externally controllable electrical power regulators  332 ,  334 ,  336 ,  338  and  340  control the electrical power from the electrical power supplies  322 ,  324 ,  326 ,  328  and  330  and are themselves in turn connected to the computer system  310 , and can be controlled via it. 
     In addition to the heating elements  14 ,  18 ,  22 ,  26  and  33 , pumps  15 ,  19  and  23  are also provided with corresponding power regulators, which can be controlled by the computer system. These power regulators are not illustrated in  FIG. 3 , for simplicity. 
     The described method can be carried out by means of the arrangement as illustrated in  FIG. 3 , by way of example as follows. The maximum total power p max  for which the overall system is designed is assumed in this example to be 45 kW. First of all, specific power levels are allocated to the individual load elements. These power levels are typically preset, in which case, for example, different electrical circuits, in particular in the externally controllable power regulators  332 ,  334 ,  336 ,  338  and  340  and in the power regulators for the pumps  15 ,  19  and  23 , which are not illustrated, can be used. It is possible to switch between these individual electrical circuits, controlled by the computer system  310 , so that different power levels can be applied to the respectively associated loads  14 ,  18 ,  22 ,  26 ,  33 ,  15 ,  19  and  23 . 
     By way of example, Table 2 shows an allocation such as this of discrete power levels to the individual load elements. In this case, the load element with the associated reference symbol is in each case shown in the first column. The respective discrete power levels are listed in the second column. All of the power levels are stated in kilowatts. In this case, in this simple example, the heating elements  14 ,  18 ,  22  and  26  each have three power levels, specifically p imax , p ireg  and p imin . The pumps  15 ,  19  and  23  in this example have only two power levels, specifically p imax =p ireg  and p min . The lowest power level p imin  is set to the value zero in this example for all of the listed loads. 
     Examples for power levels in various operating phases are shown in the third, the fourth and the fifth column, specifically in the starting phase (third column), the switched-on phase (fourth column) and the load regulation phase. Typical numerical values for this example are illustrated in the fourth column, based on a conventional control method for the dishwasher  110  illustrated in  FIG. 3 . 
     In the starting phase, that is to say immediately after the dishwasher  110  has been brought into use, the water tanks  13 ,  17  and  21  must be raised to the required operating temperature, before the washing operation of the machine can be started. In this starting phase, the maximum power is thus allocated to the heating elements  14 ,  18  and  22 . The heating  26  for the continuous-flow heater, the drying heating  33  and the pumps  15 ,  19  and  23  are in contrast not yet required in this starting phase, and are thus set to the minimum power, that is to say in this case to a power level of zero. Overall, the total power level for all of the loads in this starting phase is calculated to be a power of 45 kW, which thus corresponds exactly to the predetermined maximum value p max . Alternatively, the sum of the individual powers could also be less than p max , but in no case more than it. 
     As soon as the signal from the temperature sensors  318  indicates that the predetermined nominal temperatures (which for example are stored in the data memory  314  in the computer system  310 ) have been reached in the tanks  13 ,  17  and  21 , the computer system  310  initiates the switched-on phase. Various intermediate phase are also feasible, in which, for example, the temperature in individual tanks has already reached the nominal value, but has not in others. 
     In the switched-on phase, the regular power values p rireg  are then first of all applied to all of the loads. As is once again shown in the lowest line of Table 2, the sum of these p rireg  regular power levels is also 45 kW in this case. Once again, as an alternative, the sum of the individual power levels could also be less than p max , but in no case greater than it. The washing process can then be carried out in the dishwasher in the switched-on phase, and the machine is ready to operate. 
     If the computer system finds in the switched-on phase that one or more of the detected sensor values, for example the measured values from individual temperature sensors  318 , have risen above or fallen below predetermined nominal values (which by way of example are once again stored in the data memory  314 ) by more than respectively likewise stored tolerance values, then the computer system  310  switches over to a load regulation phase. Depending on the nature of the discrepancy, appropriate action instructions in the form of power levels for corresponding loads can, for example, be stored in one or more look-up tables in the data memory  314 . 
     As a simple example, the fifth column in Table 2 thus shows a situation as to how, for example, it would be possible to react to an increased temperature in the precleaning tank  13  and to a temperature in the main cleaning tank  17  that is lower than the associated nominal value. The power of the heating element  14  is set in an appropriate manner from the regular value of 9 kW to the minimum value of 0 kW, while in contrast the power of the heating element  18  is raised from the regular value of 6 kW to the maximum value of 15 kW. As is also evident from the last line in Table 2, the total sum of the powers applied in this case is 43 kW, that is to say slightly below the maximum permissible value of 45 kW. However, in this case, no power level for a load element is set to a higher power level than that which would exceed the maximum permissible total power p max . Thus, the available power range is therefore optimally used in this case as well. 
     As soon as the computer system  310  finds that the predetermined nominal values have been reached again (except for appropriate tolerable discrepancies), a switchover is once again carried out to regular switched-on operation. If discrepancies are found again, then the described process of load regulation is repeated as appropriate. 
     For comparison, the last column in Table 2 also shows corresponding power levels of conventional systems, in which only one specific load can in each case be switched on or off. As can be seen, a total power of 78 kW can occur in the worst case here, for which the system must be designed. 
     Analogously to the example, as illustrated in  FIG. 3 , of a multiple chamber dishwasher, the method can also be transferred to single-chamber dishwashers, or to further dishwasher types. One corresponding arrangement is illustrated in  FIG. 4 . 
     The arrangement has a single-chamber dishwasher  410 , which may, for example, be a front-loading single-chamber dishwasher or a through-feed machine. A basket  412  is held in the single-chamber dishwasher  410  in order to hold the item  414  to be washed. Furthermore, the dishwasher  410  has a tank  416  for washing lye, which can be heated via a heating element  418 . Washing liquid can be applied to the item  414  to be washed from this tank for washing lye  416 , by means of a circulation pump  420  and via a washing system for washing lye  422 , which is provided with a plurality of nozzles  424 . 
     Furthermore, the dishwasher  410  has a fresh-water tank  426 , which is in the form of a boiler. The fresh-water tank  426  can be filled with fresh water  430  via a filling valve  428 . In addition, the fresh-water tank has a heating element  432 , by means of which the fresh water  430  can be heated for rinsing at increased temperatures. The fresh-water tank  426  is in this case always filled with fresh water  430  as far as the level  434  at which the heating element  432  is covered. In order to avoid overpressure in the fresh-water tank  426  during heating, the fresh-water tank  426  is connected to the interior of the dishwasher  410  via a vent line  436 . 
     Fresh water  430  is sucked out of the fresh-water tank  426  at the induction point  438  in order to rinse the item  414  being washed with cold or else with heated fresh water  430 , by means of a fresh-water pump  438 , and is supplied to the item  414  to be washed via a washing system for fresh water  440  and a plurality of nozzles for rinsing  442 . 
     Analogously to the example illustrated in  FIG. 3 , the arrangement shown in  FIG. 4  also once again has a computer system  310  with a central processor unit  312  and a data memory  314 . The computer system is connected via a main control line  316  to the dishwasher  410 , so that all the major functions of the dishwasher  410  can be controlled via the computer system  410 . In addition, the arrangement has two electrical power supplies  444 ,  446  for the pumps  420  and  438 , as well as electrical power supplies  448  and  450  for the heating elements  418  and  432 . The functions of the electrical power supplies  444 ,  446 ,  448 ,  450  correspond to that of the power supplies  322 ,  324 ,  326 ,  328 ,  330  in  FIG. 3 . The power of the electrical power supplies  444 ,  446 ,  448 ,  450  can once again be set by means of externally controllable electrical power regulators  452 ,  454 ,  456 ,  458 , which can once again be driven by the computer system  310 . 
     Furthermore, the tanks  416  and  430  each have temperature sensors  318 , whose signals can be detected by means of a measured-data detection unit  320 , which can be read by the computer system  310 . 
     Analogously to the description relating to  FIG. 3 , the method according to the invention can also be implemented with the arrangement illustrated in  FIG. 4 . Once again, a plurality of power levels are assigned to the electrical load elements  418 ,  420 ,  432  and  438 . As described above, in this case as well, these power levels can be predetermined in a fixed form at this stage in the form of electrical circuits, for example in the power controllers  452 ,  454 ,  456  and  458 , between which it is just necessary to switch in order to apply the appropriate power levels to the load elements  418 ,  420 ,  432  and  438 . 
     In the starting phase of the dishwasher  410 , the washing liquid in the tank for the washing lye  416  must first of all be heated to the operating temperature. This washing lye is required first of all during operation, followed by the fresh water  430 . Thus, analogously to the method described above, the heating element  418  once again first of all has an electrical power corresponding to the maximum power level applied to it, while in contrast lower power levels are applied to the other load elements  420 ,  432  and  438 . For example, the pumps  420 ,  438  can thus be switched off completely in this starting phase, that is to say they have zero power applied to them. Since the fresh water  430  is also required at an increased temperature during operation, it is, however, worthwhile not completely setting the power level for the heating element  432  to zero, so that the fresh water  430  in the fresh-water tank  426  is also slowly heated up, in order to be available later during rinsing operation. 
     As soon as the temperature sensor  318  and the measured-data detection unit  320  signal that the temperature in the washing lye tank  416  has reached the desired temperature, the computer system  310  starts the switched-on phase, and the dishwasher  410  is ready to operate. The regular power levels are then applied to the load elements  418 ,  420 ,  432  and  438 . The further operating phases, which have already been described above, can also be carried out in a corresponding manner using the energy-saving method according to the invention. In this case, it should be noted that the regular power levels for the individual load elements  418 ,  420 ,  432  and  438  may be chosen to be different in the different operating phases of the dishwasher  410 . For example, the regular power level of the fresh-water pump  438  in the phase of cleaning the item  414  to be washed with washing lye from the tank  416  can thus be set to zero, since no fresh water  430  is applied to the item  414  to be washed in this phase. The regular power of this pump  438  is then reduced in a corresponding manner during rinsing operation. Alternatively, the regular power level for this pump may, however, also be kept constant. 
     The method can thus be matched in a simple manner to the various operating phases of the single-chamber dishwasher  410 . Load regulation in the event of a discrepancy between the individual operating parameters and their respective nominal values during operation can be carried out in a manner corresponding to the method according to the invention as described above. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Typical electrical power levels for the loads 
               
               
                 in a dishwasher corresponding to the prior 
               
               
                 art, during normal operation: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Heating for precleaning 14 
                 12 kW 
               
               
                   
                 Heating for main cleaning 18 
                  9 kW 
               
               
                   
                 Heating for pump rinsing 22 
                  3 kW 
               
               
                   
                 Heating for continuous-flow heater 26 
                  8 kW 
               
               
                   
                 Heating for drying 33 
                  9 kW 
               
               
                   
                 Pumps 15, 19, 23 
                  2 kW each = 
               
               
                   
                   
                  6 kW 
               
               
                   
                 total power 
                 47 kW 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Examples of power applied to individual loads on the basis of the 
               
               
                 method according to the invention, in comparison to the prior art: 
               
             
          
           
               
                   
                 p imax   
                   
                   
                 Load 
                   
               
               
                   
                 p ireg   
                 Starting 
                 Switched- 
                 regulation 
                 Prior 
               
               
                   
                 p imin   
                 phase 
                 on phase 
                 phase 
                 art 
               
               
                   
                   
               
             
          
           
               
                 Heating for 
                 24 
                 24 
                 9 
                 0 
                 24 
               
               
                 precleaning (14) 
                 9 
               
               
                   
                 0 
               
               
                 Heating for main 
                 15 
                 15 
                 6 
                 15 
                 15 
               
               
                 cleaning (18) 
                 6 
               
               
                   
                 0 
               
               
                 Heating for pump 
                 6 
                 6 
                 2 
                 6 
                 6 
               
               
                 flushing (22) 
                 2 
               
               
                   
                 0 
               
               
                 Heating for 
                 18 
                 0 
                 16 
                 16 
                 18 
               
               
                 continuous-flow 
                 16 
               
               
                 heater (26) 
                 0 
               
               
                 Heating for drying 
                 9 
                 0 
                 6 
                 0 
                 9 
               
               
                 (33) 
                 6 
               
               
                   
                 0 
               
               
                 Pumps (15, 19, 23) 
                 6 
                 0 
                 6 
                 6 
                 6 
               
               
                   
                 6 
               
               
                   
                 0 
                   
               
               
                 Sum 
                   
                 45 kW 
                 45 kW 
                 43 kW 
                 78 kW 
               
               
                   
               
             
          
         
       
     
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Inlet zone 
           2  Precleaning zone 
           3  Main cleaning zone 
           4  Pump rinsing zone 
           5  Fresh-water rinsing zone 
           6  Heat recovery zone 
           7  Dry zone 
           8  Outlet zone 
           9  Item being washed 
           10  Transport device, item being washed 
           11  Transport device, for example endless belt 
           12  Inlet trough 
           13  Tank for cleaner solution 
           14  Heating for precleaning 
           15  Pump for precleaning 
           16  Spraying system for precleaning 
           17  Tank for cleaner solution for main cleaning 
           18  Heating for main cleaning 
           19  Pump for main cleaning 
           20  Spraying system for main cleaning 
           21  Tank for solution, pump rinsing zone 
           22  Heating for pump rinsing zone 
           23  Pump for pump rinsing zone 
           24  Spraying system for pump rinsing zone 
           25  Continuous-flow heater for fresh-water rinsing 
           26  Heating, continuous-flow heater for fresh water 
           27  Mains connection for fresh water 
           28  Spraying system for fresh-water rinsing 
           29  Heat exchanger, exhaust air/fresh water 
           30  Exhaust air fan 
           31  Direction of the air flow 
           32  Fan in the dry zone 
           33  Heating in the dry zone 
           34  Direction of the air flow 
           35  Outlet trough for removal of the item being washed 
           110  Multiple chamber dishwasher 
           210  Assignment of an electrical total power p max    
           220  Assignment of power levels p ij    
           230  Determination of the optimum combination of power levels p ij    
           240  Setting of the power p ij (B) for each load element 
           310  Computer system 
           312  Central processor unit 
           314  Data memory 
           316  Main control line 
           318  Temperature sensors 
           320  Measured data detection unit 
           322  Electrical power supply 
           324  Electrical power supply 
           326  Electrical power supply 
           328  Electrical power supply 
           330  Electrical power supply 
           332  Externally controllable electrical power regulator 
           334  Externally controllable electrical power regulator 
           336  Externally controllable electrical power regulator 
           338  Externally controllable electrical power regulator 
           340  Externally controllable electrical power regulator 
           410  Single-chamber dishwasher 
           412  Basket 
           414  Item being washed 
           416  Tank for washing lye 
           418  Heating element for washing lye 
           420  Circulation pump 
           422  Washing system for washing lye 
           424  Nozzles for washing lye 
           426  Fresh-water tank boiler 
           428  Filling valve 
           430  Fresh water 
           432  Heating element for fresh-water tank 
           434  Coverage level 
           436  Vent line 
           438  Induction pump 
           440  Washing system for fresh water 
           442  Nozzles for rinsing 
           444  Electrical power supply 
           446  Electrical power supply 
           448  Electrical power supply 
           450  Electrical power supply 
           452  Externally controllable electrical power regulator 
           454  Externally controllable electrical power regulator 
           456  Externally controllable electrical power regulator 
           458  Externally controllable electrical power regulator