EP0700265B1 - Machine dish-washing process and device - Google Patents

Abstract

The process of dishwashing in an institutional dishwashing machine by adding to the wash liquor of the dishwashing machine a low-alkali content detergent composition and adding to a washing tank of the dishwashing machine a detergency booster composition containing an enzyme. Apparatus to practice the process is also disclosed.

Description

The invention is directed to a method for machine dishwashing in commercial dishwashers, in which a cleaning agent and a cleaning enhancer, preferably carbohydrate-degrading, enzyme, in particular amylase, containing this effect are added to the dishwasher. Furthermore, the invention relates to a device for performing the method, which has a detergent dosing system and a dosing system for another active ingredient with an associated pump and pump control.

A commercial dishwasher contains, for example, several tanks arranged one behind the other, from which washing or washing liquor is sprayed against the dishes passing through the dishwasher. The tanks are placed in a cascade-like manner, the washing or washing liquor passing through the tanks one after the other from the dishes outlet end to the dishes inlet end, so that the degree of contamination of the washing or washing liquor increases from the outlet end to the inlet end. Fresh water is fed to the dishwashers at the outlet end. The required amount of cleaning agent is metered into at least one wash tank, also known as a metering tank. Usually, detergent is added automatically depending on the conductivity or the pH of the wash liquor or, if liquid or powder detergent is already dissolved in water, possibly also by means of a time-controlled metering pump.

With the usual detergent concentration, the detergents used in practice often do not prevent starch deposits that form on the dishes during normal machine cleaning in a dishwasher and do not remove existing starch deposits. At certain time intervals, dishes with starch deposits will become so-called Undergo thorough cleaning. In the case of such basic cleaning, the concentration of detergent in the rinsing or washing liquor is significantly higher than in normal rinsing processes. Another alternative is to spray a highly concentrated alkaline detergent onto the dishes as part of a normal dishwashing cycle. There is also the option of performing manual tank cleaning.

From DE-A-17 28 093 it is known for cleaning dishes in household dishwashers to add a rinse aid together with amylase to the starch water to remove starch deposits on the dishes. If desired, protease or lipase can also be added to the rinse aid in addition to the amylase.

Also known from DE-A-12 85 087 is a method for machine dishwashing, in which an alkaline detergent is dosed in the main wash cycle and an enzyme-containing, in particular amylase-containing, rinse aid in the rinse and optionally pre-wash cycle is dosed into the dishwasher. This is done in order to reduce the starch formed on the dishes in the rinse and possibly pre-wash cycle. However, it is expressly pointed out that the addition of the enzyme-containing rinse aid in the main rinse cycle is not possible, since the alkalinity of the detergent would destroy the fermentation immediately. In addition, the reference to the cold pre-wash cycle shows that a dishwasher is understood to be a household dishwasher. Cold pre-wash cycles are only common in household dishwashers.

From DE-A 27 27 463 and EP-A-0 256 679 it is known to clean dishes in automatic dishwashers with an enzyme-containing low-alkaline cleaning agent. There is also no reference to commercial dishwashers in these publications. So were the experimental examples according to EP-A-0 256 679 carried out in a household dishwasher and show the instructions in DE-A 27 27 463 on dispensing devices for the cleaning agent, which hold it back before use in the dishwasher and which are usually not liquid-tight, so that water can penetrate into the dispensing device in the pre-rinse cycle that household dishwashers are also meant here.

Furthermore, an enzyme-containing detergent for avoiding scissors and stains that form in particular on glasses after drying is also known from EP-A-0 271 155. This detergent was also tested in a household dishwasher, which can be deduced from the incorrect washing time of 60 minutes for commercial dishwashers.

In the article "Enzymes in detergents for household dishwashers" by Dr. Th. Altenschöpfer in the magazine Fette, Seifen, Anstrichmittel, 73 (1971), number 7, page 464, left column, third to last paragraph, it is stated in summary that the use of enzyme-containing cleaning agents in commercial dishwashers is not possible because of the long contact times required . In connection with Table 6, this article explains that good and safe cleaning results can only be achieved with contact times of 10 to 20 minutes. Due to the short contact time in commercial dishwashers, during which the dishes are in contact with the detergent fleet, it does not appear to the specialist world to be able to prevent or break down starch deposits on the dishes with commercial detergent in commercial dishwashers.

Finally, a generic method is known from DE-A-4 110 764. Here, in a kind of pre-wash or pre-wash zone, a mechanical pre-cleaning of the dishes from coarse impurities and a spraying of the dishes with a concentrated surfactant solution and subsequent action of the concentrated surfactant solution in a commercial dishwasher carried out. These process steps can also be carried out in a separate work station before the actual dishwasher. The concentrated surfactant solution is slightly acidic to weakly alkaline and contains carbohydrate-degrading enzyme, especially amylase. The exposure time is 10 to 90 seconds, which is within the usual contact times between cleaning agents and dishes in commercial dishwashing processes. Only then is the final cleaning of the dishes carried out in a manner known per se in the main washing cycle proper, using conventional cleaning steps, including rinsing, with conventional cleaning agents which are compatible with the surfactants of the concentrated surfactant solution. Similar to the household dishwashing process according to DE-A-1 285 087, the use and metering of enzyme-containing agents in the actual main wash cycle or main wash cycle is also avoided in this process. In the pre-wash or pre-wash zone, the dishes are sprayed with a low-alkaline cleaning booster and in the main wash cycle they are cleaned with a conventional cleaning agent.

A method for machine dishwashing in commercial dishwashers, in which a detergent and a further active ingredient that supports its action are metered into the washing or washing liquor, and a device for carrying out the method, which includes a detergent dosing system and a dosing system for another active ingredient assigned pump and pump control are known from DE-A-39 20 728. In this known method for machine dishwashing in commercial dishwashers, in addition to the cleaning agent, active oxygen is metered into the metering or washing tank of the dishwasher as this further active ingredient which supports its action. In order to maintain the oxygen concentration in the wash tank when the rinsing cycle is interrupted, active oxygen is replenished into the wash tank during the interruptions.

A method and an apparatus for machine dishwashing in commercial dishwashers, in which the two different active ingredients, namely cleaning agents and, for example, a bleaching agent, are added to the washing liquor of a dishwasher by means of a detergent dosing system and a dosing system for a further active ingredient with an associated pump and pump control. is also known from US-A-3,490,467.

The object of the invention is to provide a solution which prevents the formation of a starch coating on the dishes during machine dishwashing in commercial dishwashers.

In a method of the type mentioned at the outset, this object is achieved according to the invention in that the cleaning booster is part of the low-alkaline cleaning agent formulated, in particular based on phosphate or nitriloacetic acid or its salts (NTA), and / or additionally in combination with the lower-alkaline cleaning agent, the rinsing - or washing liquor to which at least one rinsing or washing tank of the dishwasher is added.

Surprisingly, it has been shown that a low-alkaline cleaner in the usual concentration in combination with enzyme or an enzyme-containing cleaning booster leads to excellent removal and inhibition of the starch build-up on the dishes, even with the short contact times of 10 to 180 seconds customary in commercial dishwashers. Compared to known commercial dishwashing processes in which a highly alkaline cleaner or a highly concentrated, alkaline washing liquor is used, the process according to the invention is distinguished by a considerable improvement in operational and application safety. There is no longer any danger to operating personnel from etching injuries caused by highly alkaline cleaners or wash liquors.

The lower-alkaline cleaner may also contain complexing agents other than those listed, if so desired.

According to an embodiment of the invention, a concentration of 0.5 to 15 g / l of low-alkaline cleaning agent is expediently set in the rinsing or washing liquor.

It is furthermore advantageous if the low-alkaline cleaning agent is metered in in use concentration with a pH of 7 to 11, preferably 9.1 to 10.8, which is also provided by the invention.

A concentration of 0.05 to 2 g / l of cleaning enhancer is expediently set in the rinsing or washing liquor according to a further embodiment of the invention.

In a further development, the invention provides that the enzyme-containing cleaning booster during normal dishwasher operation with a normal cleaning concentration in the washing or washing liquor of 0.5 to 8 g / l and / or during a periodic basic cleaning with an increased cleaning concentration in the washing or washing liquor of 3 to 15 g / l is metered into the rinsing or washing liquor.

Since enzymes in the washing or washing liquor of a commercial dishwasher are not stable in the presence of cleaning agents, the invention provides in one embodiment that the cleaning booster is replenished to the extent of the enzyme breakdown.

Furthermore, the enzyme breakdown or the enzyme decay (consumption) in standstill phases of the dishwasher operation is lower than during the wash phases, so that the invention provides in an expedient development that the replenishment in standstill phases is low in comparison to wash phases.

The enzyme-containing cleaning booster, like conventional cleaning agents, can either be metered into the at least one dosing or washing tank of the dishwasher, but also into the liquid flowing through the rinse line and / or the spray system of the commercial dishwasher, and in this way fed to the dishwasher. The invention therefore provides as a further development that detergents and cleaning boosters are metered separately into the washing or washing liquor.

According to a further development of the invention, it is also advantageous that the enzyme-containing detergent booster is metered into the rinsing or washing liquor in parallel or subsequently to the lower-alkaline detergent.

It has proven to be particularly advantageous if a cleaning booster is metered in, which contains about 0.01 to 0.6% by weight, preferably 0.45 to 0.55% by weight, of enzyme, in particular amylase, and 10 to 25 % By weight, preferably 15 to 20% by weight, of propylene glycol, in particular 1,2-propylene glycol, and a corresponding amount of water, as provided by the invention in one embodiment.

The cleaning enhancer can contain as an enzyme amylase, lipase, protease or other, in particular carbohydrate-degrading, enzymes, either individually or in suitable mixtures.

It is possible that an enzyme-free, liquid or powdery, low-alkaline cleaning agent is used in combination with an enzyme-containing cleaning booster. In this case, the invention provides in one embodiment that an enzyme-free, in particular liquid, low-alkaline cleaning agent is metered into the rinsing or washing liquor during detergent dosing times, and the enzyme-containing cleaning booster is metered in parallel to the extent of the detergent consumption. In contrast to the case below of combining enzyme-containing cleaning agents with enzyme-containing cleaning agents, in the case of combining enzyme-free cleaning agents with enzyme-containing cleaning enhancers, even during the metering or dosing times of cleaning agents, metered into the at least one metering or washing tank of the commercial dishwasher parallel to the cleaning agent enzyme-containing cleaning enhancer.

However, it is also possible that enzyme is already incorporated into the liquid or powdered low-alkaline cleaning agent. In particular, a solid enzyme carrier, for example amylase carrier, can be incorporated into a powdery, low-alkaline cleaner. This enzyme-containing cleaning agent is then used in combination with the enzyme-containing cleaning enhancer. In this case, the invention provides in an embodiment that during detergent dosing times in the rinsing or washing liquor, an enzyme for immediate rinsing containing a sufficient amount, in particular powdery, low-alkaline cleaning agent and immediately after completion or during interruptions or downtimes of the dishwasher operation and / or Dosing pauses of the cleaning agent, the enzyme-containing cleaning booster is metered into the rinsing or washing liquor. In this case, the enzyme-containing cleaning booster is therefore only metered into the washing or washing liquor during or immediately after the dosing pauses of the cleaning agent and / or the interruptions or downtimes of the dishwasher operation. During the times of the active rinsing cycle, during which the detergent is dosed into the washing tank of the dishwasher, the enzyme-containing cleaning booster is not dosed.

It is expedient here that the enzyme-containing cleaning enhancer is metered into the rinsing or washing liquor to maintain the enzyme concentration to the extent of the enzyme breakdown or enzyme decay (consumption), which the invention further provides.

It is known that enzymes such as amylase, lipase or protease are not stable in the washing liquor of commercial dishwashers. After being washed into the wash tank of a commercial dishwasher Enzyme-containing cleaning agents or cleaning boosters lose their effect relatively quickly. In the event of interruptions or downtimes in the operation of the dishwasher and / or dosing of the cleaning agent or cleaning booster, enzyme degradation or enzyme breakdown (consumption) occurs, in which the enzyme content in the washing or washing liquor often drops at around 40 to 60% per hour. Depending on the degree of consumption, z. B. even after a half-hour break in machine operation, the enzyme content dropped to well below half. In order to ensure that after an interruption or standstill phase of the dishwasher operation and / or a dosing pause of the cleaning agent or the cleaning booster, an enzyme concentration sufficient to achieve a satisfactory cleaning performance is again present in the wash liquor, the invention provides in one embodiment that the washing under conditions in a commercial Dishwasher undergoing enzyme degradation or enzyme decay (consumption) enzyme-containing cleaning enhancers in the event of interruptions or downtimes in the dishwasher operation and / or dosing intervals of the cleaning agent or cleaning enhancer in the washing or washing liquor in an amount that is added during the respective interruption or downtime phase and / or dosing breakdown occurring enzyme breakdown or enzyme breakdown (consumption) compensates so that after the end of the respective interruption or standstill phase and / or Do the machine operation is continued with essentially the same enzyme concentration in the rinsing or washing liquor as before the respective interruption or standstill phase and / or dosing break. This ensures that with each active cleaning phase of the washing cycle in a commercial dishwasher there is a sufficiently high enzyme concentration in the wash liquor to achieve the desired cleaning result (prevention of the build-up or removal of the starch deposit on the dishes).

In an embodiment, the invention provides that the enzyme-containing cleaning enhancer is added to the rinsing or washing liquor to maintain the enzyme concentration immediately after completion or during the interruptions or standstill phases and / or the dosing pauses of the detergent to the extent of the enzyme breakdown or enzyme decay (consumption).

The invention provides two alternatives for the metering-in or metering-in of the enzyme-containing cleaning booster. On the one hand, the enzyme-containing cleaning booster can be dosed or re-dosed during the interruptions or standstill phases of the dishwasher operation and / or dosing pauses of the cleaning agent, and on the other hand the dosing or re-dosing of the enzyme-containing cleaning booster can be carried out immediately after the interruptions or downtime phases of the dishwasher operation and / or Dosing intervals of the cleaning agent take place.

In the first alternative, the invention provides in a further embodiment that the enzyme concentration in the rinsing or snacking liquor is maintained during the respective interruption or standstill phase and / or during the dosing pauses of the cleaning agent by maintenance dosing of the enzyme-containing cleaning booster. It is advantageous here if the maintenance dosing takes place in individual dosing strokes, as the invention provides in a further development.

In the case of this first alternative, the embodiment accordingly aims primarily at maintenance dosing of the enzyme-containing cleaning booster in the downtimes of the dishwasher between two successive washing phases or during the dosing pauses between two dosing times of the cleaning agent. The maintenance dosing ensures that in the extent of the enzyme breakdown or enzyme decay (consumption) new, enzyme-containing cleaning boosters in the at least one dosing or Wash tank arrives. The washing tank or the washing liquor of the dishwasher is thus always ready for a new washing phase. At the beginning of each rinsing phase, a wash liquor which has been sufficiently admixed with enzymes or has a sufficiently high enzyme concentration is immediately available. If enzyme is used for immediate rinsing of a detergent containing itself, in particular in powder form, in sufficient quantities, the enzyme-containing cleaning booster is replenished into the at least one wash tank only during the standstill phases or dosing pauses of the detergent to the extent of the enzyme breakdown. If an enzyme-free cleaning agent, in particular a liquid cleaner, is used, in addition to maintenance dosing during the dosing times for the cleaning agent, the enzyme-containing cleaning booster is dosed in parallel. When the enzyme-free cleaning agent is used, enzyme is metered into the wash tank or the rinsing or washing liquor during the rinsing phases of the amount of detergent used and during the standstill phases or the detergent dosing breaks to the extent of the enzyme breakdown or enzyme breakdown. The parallel dosing enables the use of enzyme-containing cleaning boosters such as B. amylase solution that cannot be formulated with the usual enzyme-free alkaline, in particular lower-alkaline, cleaning agents. During the rinsing phase, liquid or powder detergents are metered in depending on the measured conductivity or the measured pH value or time-controlled only during certain metering times. If the corresponding intermediate times or detergent dosing breaks become so long that an amount of enzyme which has an adverse effect on the cleaning performance of the next rinsing phase has broken down, it is within the scope of the invention, also in the intermediate or control pauses of the parallel dosing occurring during the rinsing phase, to the extent of Enzyme digestion in accordance with enzyme-containing cleaning enhancers, also as maintenance dosing.

For maintenance dosing, it can be expedient if the enzyme delivery rate of the maintenance dosing is optimized on the basis of an enzyme activity determination, as is further provided by the invention. After knowing the rate of decay of the enzymes, it may be sufficient to add detergent enhancers at certain intervals.

In this context, the invention further provides that the maintenance dosage of the enzyme-containing cleaning booster is started after each disintegration of about 20% of the original enzyme content in the rinsing or washing liquor.

The other of the two alternatives explained above, according to one embodiment of the invention, is that a surge dose is carried out immediately after the end of the respective interruption or standstill phase and / or dosing pause, in which a quantity of enzyme-containing cleaning booster is added to the rinsing or washing liquor, which during the The duration of the respective interruption or standstill phase and / or dosing break corresponds to enzyme degradation or enzyme breakdown (consumption). In this alternative, after the end of the interruption or standstill phase of the dishwasher operation and / or after the end of a detergent dosing break, the enzyme-containing cleaning booster is dosed, the amount of enzyme-containing cleaning booster added during the dosing being adapted to the duration of the interruption and dimensioned such that it compensates for the enzyme breakdown or decay (consumption) that occurred during the interruption. Accordingly, during the interruption or standstill phase of the machine operation and / or the detergent dosing break, no enzyme-containing cleaning booster is fed to the at least one dosing or wash tank or the washing or washing liquor of the dishwasher. The enzyme-containing cleaning booster is supplied only after the interruption or dosing break has ended within a relatively short time, so that the amount of enzyme which was consumed during the interruption or dosing break is replaced. The measurement of the amount of the cleaning booster added during the batch dosing is carried out as a function of the duration of the interruption and / or dosing pause and as a function of the course of the enzyme decay which can be described by a mathematical function, for example an e-function. This ensures that the enzyme consumed is replaced fairly accurately without substantial underdosing or overdosing.

In order to achieve a precisely measured, needs-based dosage, it is taken into account according to a preferred further embodiment of the invention that the time course of enzyme consumption essentially follows an exponential function, the concentration decreasing exponentially starting from an initial concentration. A practice-oriented pulse dosage after a pause t must consequently follow the complementary function of the course of the enzyme consumption.

In the case of surge dosing as well as maintenance dosing, it is possible for the enzyme-containing cleaning booster to be metered in during the dosing times in parallel, if an enzyme-free cleaning agent is used.

In a device of the type mentioned at the outset for carrying out the method, the object is achieved according to the invention by a metering system for metering an enzyme-containing cleaning amplifier which is separate from the detergent metering system and which has an operating state for maintenance metering during interruptions or downtimes of the dishwasher operation and / or metering pauses of the detergent. Dosing system and / or an operating state for batch dosing after interruptions or standstill phases of the dishwasher operation and / or dosing pauses of the detergent dosing system.

The device according to the invention for carrying out the method is fundamentally characterized by a metering system for the enzyme-containing cleaning booster, which is separate from the detergent dosing system, the latter having an operating state for maintenance dosing and / or an operating state for impact dosing. The detergent dosing system can be designed in a conventional manner, for. B. as a metering pump in a liquid cleaner or as fresh water or liquor in a powder cleaner. In addition, according to the invention there is essentially only the dosing system for the enzyme-containing cleaning booster which is separate or separate from the detergent dosing system. This has either an operating state for maintenance dosing or an operating state for surge dosing and is provided with the technical equipment necessary for the respective operating state. In addition to this embodiment, in which the cleaning amplifier dosing system has either only technical devices for the operating state of maintenance dosing or technical devices for the operating state of shock dosing, it is also possible to equip the cleaning amplifier dosing system with technical devices for both operating states, so that the operating personnel can the desired operating state can be freely selected. The device thus enables maintenance dosing during the interruptions or standstill phases of the dishwasher operation and / or the cleaning agent dosing breaks or a shock dosing immediately after the end of interruptions or standstill phases of the dishwasher operation and / or cleaning agent dosing breaks, so that a through Enzyme degradation or decomposition-induced decrease in enzyme activity is compensated for during this time. Such a subsequent or additional metering is necessary if the cleaning agent supply to the commercial dishwasher is carried out, as usual, via a regulation which does not take into account the enzyme content in the washing liquor. In contrast to the enzyme content, the detergent concentration in the washing liquor remains essentially constant during the interruptions or downtimes of the dishwasher. Without the additional metering of enzyme, otherwise only cleaning agents corresponding to the fresh water supply would otherwise be metered into the at least one metering or washing tank or the washing or washing liquor of the dishwasher at the beginning of a new rinse cycle. There would then be a deficit in enzyme content and thus an unsatisfactory washing result, at least with regard to starch soiling. This problem is overcome by the device according to the invention.

In one embodiment of the device for carrying out the shock metering, the device in a development of the invention contains a counter, to which pause pulses are regularly supplied during the interruption times. With these pause pulses, the counter reading is not increased in a linear manner, but rather in a step-wise approximated function that is complementary to the enzyme decay, in particular an e-function, in order to finally approach a predetermined final value asymptotically with a minimal count rate. After the end of the interruption or standstill phase and resumption of machine operation, the counter is counted down linearly from the achieved counter reading at a constant clock rate until the counter reading reaches zero. During the counting process, the down counting pulses activate a pump, which effects the surge metering. The duration of the surge metering therefore depends on the meter reading reached during the interruption time. The duration of the shock metering is orders of magnitude shorter than the duration of the interruption times in question. The surge dosage thus compensates for the drug consumption of several 10 minutes to hours within a period of seconds. The level of the meter reading is therefore a measure of the duration of the surge metering. This duration is in any case much shorter than the duration of possible break times, so that the shock dosage of the enzyme-containing cleaning boosters occur at a much higher rate than the breakdown or decay (consumption) of the enzyme in the wash liquor. After a very short time of a few minutes, the enzyme consumption of several 10 minutes is compensated in this way. This type of shock metering is not only carried out immediately after interruptions or downtimes in the dishwasher operation, but if desired also immediately after the detergent dosing breaks.

The term "counter" is to be understood broadly in this context. It includes any counting device that counts supplied pause pulses according to a given function and thus also non-linear, e.g. B. following an e-function enables counting. The variation in the time interval of the pause pulses can be used to accelerate (compress) or decelerate (stretch) the counting process in the time domain. The pause pulses can be present at a constant time interval and can be multiplied by a factor whose time profile corresponds to an e-function. On the other hand, it is also possible to feed the pause pulses to the counter at different time intervals. Finally, the counter can also contain a summing device which increases the counter reading by a time-varying amount with each pause pulse.

In a further embodiment, the invention provides for devices with the operating state of maintenance dosing as well as for devices with the operating state of shock dosing that the dosing system for the enzyme-containing cleaning booster additionally has an operating state which promotes parallel to the cleaning agent dosing system for parallel dosing when the cleaning agent dosing system is switched on. According to this embodiment, both enzyme-containing and enzyme-free cleaning agents can be used with the device, the parallel dosing allowing the addition of enzyme-containing cleaning enhancers when using enzyme-free cleaning agents. The parallel dosing and the maintenance dosing or the surge dosing differ essentially only in that per unit of time in each case in the metering tank or the rinsing or washing liquor conveyed amount of enzyme-containing cleaning enhancer.

It is advantageous if a frequency-controlled peristaltic pump or a diaphragm pump is provided for conveying the enzyme-containing cleaning amplifier, as the invention further provides. Such a pump can be operated with a number of pump strokes per unit of time corresponding to the enzyme breakdown. Relatively few pump strokes are then sufficient for maintenance dosing, while a much larger number of pump strokes are required for surge dosing and / or if necessary for parallel dosing when using an enzyme-free cleaner. In practice, it has therefore proven to be expedient if the associated frequency control of the pump has a first control range for maintenance dosing and a second control range for the dishwashing phase of the dishwasher when the detergent dosing system is switched on, with a significantly increased delivery rate compared to the dose in the first control range. as the invention finally provides in an embodiment.

Fig. 1

ein Blockschaltbild von Reinigungsmittel-Dosiersystem und Reinigungsverstärker-Dosiersystem für flüssiges, enzymfreies Reinigungsmittel und für flüssigen, enzymhaltigen Reinigungsverstärker,

Fig. 2

ein Funktionsdiagramm für eine Parallel- und Unterhaltsdosierung von enzymhaltigem Reinigungsverstärker bei Verwendung von enzymfreiem Reinigungsmittel,

Fig. 3

ein Blockschaltbild von Reinigungsmittel-Dosiersystem und Reinigungsverstärker-Dosiersystem für enzymhaltigen Pulverreiniger und flüssigen, enzymhaltigen Reinigungsverstärker,

Fig. 4

ein Funktionsdiagramm für eine Unterhaltsdosierung von enzymhaltigem Reinigerverstärker bei Verwendung von enzymhaltigem Reinigungsmittel,

Fig. 5

ein schematisches Blockschaltbild einer Vorrichtung für eine Stoßdosierung,

Fig. 6

ein Diagramm zur Veranschaulichung der theoretischen Dosierfunktion und der durch einen Zählalgorithmus des Zählers angenäherten Funktion bei der Stoßdosierung und in

Fig. 7

den zeitlichen Verlauf der Enzymkonzentration in der Waschflotte während einer Betriebsunterbrechung und anschließender Stoßdosierung.

The invention is explained below with reference to the drawing, for example. This shows in

Fig. 1

a block diagram of detergent dosing system and cleaning amplifier dosing system for liquid, enzyme-free cleaning agent and for liquid, enzyme-containing cleaning amplifier,

Fig. 2

1 shows a functional diagram for parallel and maintenance dosing of enzyme-containing cleaning boosters when using enzyme-free cleaning agent,

Fig. 3

a block diagram of detergent dosing system and cleaning amplifier dosing system for enzyme-containing powder cleaner and liquid, enzyme-containing cleaning amplifier,

Fig. 4

a functional diagram for a maintenance dosage of enzyme-containing Detergent booster when using enzyme-containing detergent,

Fig. 5

1 shows a schematic block diagram of a device for shock metering,

Fig. 6

a diagram illustrating the theoretical dosing function and the approximated by a counting algorithm of the counter function in the batch dosing and in

Fig. 7

the time course of the enzyme concentration in the wash liquor during an interruption in operation and subsequent surge dosing.

1 shows the detergent dosing system for liquid, enzyme-free, low-alkaline cleaning agent 2 assigned to a commercial dishwasher, as is explained below, for example, in connection with FIG. 5, and the cleaning amplifier dosing system for liquid, enzyme-containing cleaning enhancer assigned to the commercial dishwasher 5. A conventional liquid detergent metering pump 1 delivers liquid, enzyme-free cleaning agent 2 from a liquid detergent tank, for example regulated via a conductivity or pH value measurement, through a line 3 to at least one (not shown) metering or washing tank of a dishwasher. In parallel with the liquid cleaner metering pump 1, a frequency-controlled peristaltic pump 4 is provided, which also conveys from a liquid, enzyme-containing cleaning booster 5 through a line 6 to the above-mentioned, at least one metering or washing tank. This dosing system for liquid-made, enzyme-containing cleaning boosters 5 can be controlled by means of internal and / or external electronics in such a way that a function diagram according to FIG. 2 is established, i.e. maintenance dosing 17, 18 and, if necessary, parallel dosing 16 of cleaning booster 5 in addition to the dosing of cleaning agents is possible.

2 shows in three lines 7, 8 and 9 different on and off states (1/0) depending on the time t. In the 7th The top line labeled symbolizes the operating state of the commercial dishwasher. The rinsing phases or switch-on states are denoted by 10, the interruptions or standstill phases are denoted by 11. The second line, designated 8, shows the dosage of the enzyme-free cleaning agent 2, ie the active operating state of the liquid cleaner metering pump 1. Depending on the conductivity measured in at least one washing tank of the dishwasher or the pH of the washing or washing liquor located in the dishwasher, in this exemplary embodiment a two-time start of the metering pump 1 is assumed during a machine switch-on state 10. The corresponding two detergent dosing times are designated 12 and 13. An intermediate dosing pause is indicated by 14 and the dosing pause corresponding to the interruption or the standstill phase 11 of the dishwasher operation is identified by 15. In the third line, designated 9, the dosage of the enzyme-containing cleaning amplifier 5, ie the active operating state of the peristaltic pump 4, is given.

As can be seen from FIG. 2, during the detergent dosing times 12, 13 of the detergent dosing pump 1 there is a parallel dosing 16 of the cleaning amplifier 5 with a rapid sequence of individual pump strokes of the peristaltic pump 4. Each individual pump stroke is in line 9 of FIGS also in line 9a of Fig. 4 - shown as a single vertical line. In contrast, the work of the peristaltic pump 4 is very slowed down during the dosing breaks 14, 15 of the dishwasher; In the corresponding maintenance doses 17, 18, significantly fewer pump strokes are carried out per unit of time than during parallel dosing 16 in the rinsing phases 10 or the detergent dosing times 12, 13. As can be seen, the liquid detergent 2 is not replenished during the interruption or standstill phase 11 of the dishwasher (Detergent dosing break 15). Such dosing is not necessary since the concentration of detergent in the wash liquor will not be significantly reduced. Only the enzyme breakdown or enzyme decay (consumption) during the standstill phase 11 is compensated for by the slowed down metering or maintenance metering 17 during this period. It can be cheap for longer Dosing pauses 14 in the dishwashing phases 10 of the dishwasher provide individual pump strokes for maintenance dosing 18 to compensate for the constant enzyme breakdown or decay (consumption) during this time.

In the event that a dishwasher detergent 19 already contains enzymes, which is possible especially with powder detergents, a parallel dosage of enzyme-containing cleaning booster 5 does not generally have to be provided, rather a maintenance dosage is sufficient. For this case, an embodiment from FIGS 3 and 4 can be seen, with FIG. 3 the detergent dosing system assigned to a commercial dishwasher for an enzyme-containing, low-alkaline powder cleaner 19 and the separate dosing system for the enzyme-containing liquid cleaning booster 5 and FIG. 4 in the three lines 7a, 8a and FIG. 9a shows the different switch-on and switch-off states (1/0) of the commercial dishwasher and the metering systems as a function of the time t. 3 consists of a funnel 20 with an enzyme-containing, low-alkaline powder cleaner 19 filled therein. As is known from conventional dosing systems, the enzyme-containing powder cleaner 19 is dosed in the funnel 20 via a fresh water or liquor flush 21 and a line 22 to at least one dosing or wash tank of a commercial dishwasher (arrow direction).

In addition, according to FIG. 3, a dosing system for enzyme-containing cleaning booster 5 with a frequency-controlled peristaltic pump 4 is provided, which also conveys the enzyme-containing cleaning booster 5 from a tank via a line 6 to the at least one dosing or washing tank of the dishwasher. In contrast to the case of FIG. 1/2, the peristaltic pump 4 according to FIG. 3/4 only works during the standstill phase 11 of the dishwasher and possibly during the dosing pause 14, as indicated in line 9a of FIG. 4. Lines 7a and 8a show identical operating states as lines 7 and 8 according to the embodiment of FIG. 1/2. 3 and 4 in the metering 12, 13 of enzyme-containing cleaner 19 during the rinsing phases 10, enzyme is already metered into the at least one metering or wash tank, this is omitted Embodiment a parallel dosing of enzyme-containing cleaning booster during the dosing times 12 and 13. Only during the interruption or standstill phase 11 or the cleaning agent dosing pause 15 is the enzyme-containing cleaning booster 5 dosed in the form of a maintenance dosing 17. In addition, it can be advantageous under certain circumstances Dosing pauses 14 between two detergent doses 12 and 13, similar to the embodiment according to FIG. 2, to provide one or more dosing strokes as maintenance dosing 18, which is also shown in line 9a of FIG. 4.

A modification of a frequency-controlled peristaltic pump 4, 27 is preferably used to operate the maintenance metering 17, 18 and the shock metering SD explained below as well as the desired parallel metering 16, the pump used in the maintenance metering in FIGS. 1 and 3 with the reference numerals 4 and the pump used in the surge metering is provided with the reference number 27 in FIG. 5. Two control ranges for frequency control are possible, firstly an area I for parallel dosing 16 or the shock dosing SD explained below with a delivery rate range of 8 to 290 ml / min and secondly an area II for maintenance dosing 17, 18 with a delivery rate range of 1, 5 to 3.5 ml / min. These two control ranges can be selected externally so that readjustment is possible according to the washing result. Of course, it is also possible to provide a separate pump for each type of metering for the desired delivery range, or in the case of surge metering and parallel metering, a pump with only one control range for both metering types.

Instead of the maintenance doses 17, 18 shown in line 9 of FIG. 2 in connection with the parallel doses 16 or the maintenance doses 17, 18 shown in line 9a of FIG. 4 without parallel dosing, the addition or subsequent dosing of enzyme-containing cleaning boosters 5 can also be carried out by a surge metering SD. In contrast to the maintenance doses 17, 18, which takes place during the interruption or standstill phase 11 and / or the cleaning agent dosing breaks 14, 15, the shock dosing SD becomes immediate after the end of a Interruption or standstill phase 11 and / or a detergent dosing break 14, 15 activated. The corresponding function diagrams for a surge dose SD in lines 7, 7a and 8, 8a would not differ from the function diagrams shown in FIGS. 2 and 4 and would differ in lines 9, 9a in that maintenance doses 17, 18 are omitted and instead after the end of the standstill phase 11 and / or the detergent dosing pauses 14, 15 or at the beginning of the rinsing phases 10 or the detergent dosing times 12, 13, the at least one dosing or washing tank of the dishwasher-containing cleaning amplifier 5 is added to the at least one dosing or washing tank. The shock metering is explained in more detail below with reference to FIGS. 5 to 7.

5 shows a commercial dishwasher 23 through which the dishes to be washed are conveyed from left (inlet end) to right (outlet end). The dishwasher 23 contains several tanks one behind the other, from which washing or washing liquor is sprayed against the dishes in order to then run back into the tanks. The tanks are cascaded together in a known manner, the washing or washing liquor passing through the tanks in succession from the outlet end (right) to the inlet end (left), so that the degree of contamination of the washing liquor increases from the outlet end to the inlet end.

At the outlet end, water is introduced into the dishwasher 23 and additionally from a detergent tank 24 low-alkaline cleaning agent 2, which is contained in the detergent tank 24 in liquid form. The cleaning agent 2 is conveyed by a pump 25 in metered form. This pump 25 is driven by a pump control unit 26. The detergent 2 is dosed as a function of the conductivity or pH of the washing liquor contained in the dishwasher 23. The pump control unit 26 controls a further pump 27, which doses a liquid, enzyme-containing cleaning amplifier 5 into the dishwasher 23 from a tank 28. The cleaning booster contains enzymes such as amylase, lipase or protease. The cleaning amplifier 5, which is contained in the tank 28 in liquid form, is fed into the dishwasher 23 by the pump 27, which is preferably a peristaltic pump. The pump 27 is controlled by pulses that it are supplied via a control line 29. The pump is driven by a stepper motor, each pulse in the control line 29 corresponding to a specific delivery rate of the pump 27. The control line 29 is connected to an operating pulse line 30 coming from the pump control unit 26. The operating pulse line 30 supplies operating pulses 10 during the operating state 10 of the dishwasher, the frequency of which is dimensioned such that the pump 27 maintains a certain concentration of enzyme-containing cleaning amplifier 5 in the washing liquor, that is to say a parallel metering 16 is carried out. In the event of an interruption in operation or a standstill phase 11 of the dishwasher or dosing breaks 14, 15, the pump control unit 26 does not deliver any pulses to the pump 25 for the cleaning agent 2 and likewise does not supply any operating pulses to the operating pulse line 30 2 illustrated example analog case of a shock metering (explained below) in combination with a parallel metering 16 before.

A counter 32 is connected to a pause pulse line 31 of the pump control unit 26. The pause pulse line 31 supplies pulses to the counter 32 at a constant time interval in the event of an interruption in operation or a standstill phase 11 of the dishwasher and / or during dosing pauses 15 and possibly dosing pauses 14.

The counter 32 counts non-linearly in the manner shown in FIG. 6. 6, the pause time t is plotted along the abscissa during an interruption or standstill phase 11 and / or a dosing pause 14, 15 and the counter reading n along the ordinate. In this embodiment, a pause pulse is delivered every minute. With each pause pulse, the counter reading of the counter 32 is increased by a varying counting step. The size of the counting steps decreases with increasing pause time t. The counting capacity of the counter 32 here is 128. The time course of the counter reading corresponds to a stair curve 33 which is approximated to an e-function 34.

In this embodiment of the invention, it is assumed that the time course of the enzyme breakdown or enzyme decay (consumption) during the pause time t essentially corresponds to the following exponential function (consumption function): $${\text{C.}}_{\text{t}}{\text{= C}}_{\text{O}}{\text{* e}}^{\text{-lt}}\text{.}$$

, wobei τ die Zehrungszeitkonstante ist.Here C _{t is} the enzyme concentration at time t, C _{0 is} the initial concentration of the enzyme and $\text{λ = 1 / τ}$

, where τ is the consumption time constant.

The addition of enzyme-containing cleaning booster 5 after a pause t takes place according to the function complementary to the drainage function $${\text{V}}_{\text{t}}{\text{= V}}_{\text{Max}}{\text{* (1 - e}}^{\text{-lt}}\text{).}$$

Here V _{t is} the shock metering time for a pause time of t and V _max the maximum shock metering time. This function V _t corresponds to the ideal curve 34 from FIG. 6, which is approximated by the stair curve 33. In terms of circuitry, the stair curve 33 is implemented in the counter 32 by means of a programmable logic module (PLD). The non-linear counting function is achieved by varying the counting step. The clock rate of the pause pulses is adapted to the drainage function of the enzyme or the enzyme-containing cleaning amplifier 5. The maximum counter reading n _max of counter 32 is 128, which corresponds to a resolution of 7 bits.

After the pause time t, d. H. at the beginning of the operating phase 10 or at the start of the metering times 12 or possibly 13, the counter reading of the counter 32 is counted linearly in steps from 1 down to 0. 35 pulses are generated at the counter output, which are supplied to the pump 27 via the control line 29. The pulses generated when counting down the counter 32 at the output 35 cause the surge metering by the pump 27. When the counter reading 0 is reached, the surge metering is ended.

FIG. 7 shows the time course of the enzyme concentration C in the wash liquor in the event of an interruption or standstill phase 11 in the dishwasher operation or a dosing break 14, 15, the length of which is t ₁ . The enzyme concentration C / C ₀ normalized to the normal value C ₀ is given along the ordinate.

After the start of the break, the enzyme concentration drops exponentially from the value 1. The break in operation, the duration of which is t ₁ , ends at the start of the surge metering duration t ₂ . With the end of the period t ₁ or the beginning of the period t ₂ , the operation of the dishwasher begins, that is, the active operating state 10 or the dosing times 12, 13, with a shock metering SD being carried out in the initial phase. In the course of this surge dosing, the enzyme concentration rises linearly steeply to the normal value of "1". The subsequent operation is then carried out with this normal concentration. The duration t _{2 of} the shock metering SD is, for example, 1 to 2 minutes and is considerably shorter than the break t ₁ .

wobei V_max die maximale Stoßdosierzeit ist.During the pause time t _1, the counter 32 increments as a result of the pause pulses, the counter reading n developing in accordance with curve 33 in FIG. 6 and approaching asymptotically to the maximum counter reading n _max , which is finally reached when the pause in operation Dishwasher is not interrupted beforehand. The maximum counter reading n _max corresponds to the maximum surge metering time. The maximum count is reached when the pause time is about 5 τ, where τ is the consumption time constant of the enzyme. The clock rate of the counter 32 when counting down is chosen so that the maximum concentration C ₀ of enzyme in the wash liquor is just reached again at the maximum burst dosing time. The clock rate R in 1 / s is $$\text{R =}\frac{{\text{n}}_{\text{Max}}}{{\text{V}}_{\text{Max}}}\text{,}$$

where V _{max is} the maximum shock dosing time.

Depending on the consumption rate of the enzyme, the maximum count is reached after a break of 0.5 to 3 hours.

In the above-described methods for dosing cleaning agents 2, 19 and enzyme-containing cleaning boosters 5, a low-alkaline cleaner based on phosphate or nitrilotriacetic acid or its salts (NTA) are used as cleaning agents in the devices described. and metered an amylase-containing cleaning booster 5 into the dishwasher. In addition to or instead of amylase, the cleaning enhancer can also contain lipase or protease. A cleaning amplifier based on Thermamyl 300 L (NOVO), consisting of 0.55% by weight of amylase, 18.0% by weight of propylene glycol - 1.2, 72% by weight of water, 9.45, is preferably used % By weight of residual water and salts are used. Cleaners 2, 19 and / or cleaning boosters 5 can be metered into at least one washing or dosing tank of the dishwasher and / or the rinse line and / or the spraying device of the dishwasher.

In processes without maintenance or batch dosing, the enzyme-containing cleaning booster is used during regular dishwasher operation with a normal cleaning agent concentration in the washing or washing liquor of 0.5 to 8 g / l and / or a periodic basic cleaning with an increased concentration of 3 to 15 g / l in the rinsing or washing liquor is only metered in parallel or subsequently to the lower alkaline detergent of the rinsing or washing liquor. It is sufficient to equip a commercial dishwasher with two dosing systems, one for the cleaner and one for the cleaning booster. For example, these can be two metering pumps that can be operated parallel to one another.

Claims (28)

1. A process for machine dishwashing in institutional dishwashing machines (23) in which a detergent (2,19) and a detergency booster (5) containing an enzyme, preferably a carbohydrate-degrading enzyme, more particularly amylase, are introduced into the dishwashing machine (23), characterized in that the detergency booster (5) is added to the wash liquor in at least one washing tank of the dishwashing machine (23) as part of the low-alkali detergent (2,19), more particularly based on phosphate or nitrilotriacetic acid or salts thereof (NTA), and/or additionally in combination with the low-alkali detergent (2,19) and in that the wash liquor is circulated and, at the same time, sprayed onto the articles to be washed.
2. A process as claimed in claim 1, characterized in that a concentration of 0.5 to 15 g/l of low-alkali detergent (2,19) is established in the wash liquor.
3. A process as claimed in claim 1 or 2, characterized in that the low-alkali detergent is introduced in the in-use concentration with a pH value of 7 to 11 and preferably in the range from 9.1 to 10.8.
4. A process as claimed in any of the preceding claims, characterized in that a concentration of 0.05 to 2 g/l of detergency booster (5) is established in the wash liquor.
5. A process as claimed in any of the preceding claims, characterized in that the enzyme-containing detergency booster (5) is added to the wash liquor during regular operation of the dishwashing machine at typical detergent concentrations of 0.5 to 8 g/l in the wash liquor and/or during periodic thorough cleaning at an increased concentration of detergent in the wash liquor of 3 to 15 g/l.
6. A process as claimed in any of the preceding claims, characterized in that more detergency booster (5) is added at a rate commensurate with degradation of the enzyme.
7. A process as claimed in claim 6, characterized in that the amount added in stoppage phases (11) is small by comparison with wash phases (10).
8. A process as claimed in any of the preceding claims, characterized in that the detergent (2,19) and the detergency booster (5) are separately introduced into the wash liquor.
9. A process as claimed in any of the preceding claims, characterized in that the enzyme-containing detergency booster (5) is introduced into the wash liquor at the same time as or after the low-alkali detergent (2,19).
10. A process as claimed in any of the preceding claims, characterized in that the detergency booster (5) introduced contains around 0.01 to 0.6% by weight and preferably 0.45 to 0.55% by weight of enzyme, particularly amylase, and 10 to 25% by weight and preferably 15 to 20% by weight of propylene glycol, more particularly 1,2-propylene glycol, and a corresponding quantity of water.
11. A process as claimed in any of claims 1 to 10, characterized in that an enzyme-free, more particularly liquid, low-alkali detergent (2) is introduced into the wash liquor during detergent addition times (12,13) and in that the enzyme-containing detergency booster (5) is introduced in parallel (16) as the detergent is consumed.
12. A process as claimed in any of claims 1 to 10, characterized in that a low-alkali detergent (19), more particularly a powder-form low-alkali detergent, containing sufficient quantities of an enzyme for immediate washing is introduced into the wash liquor during detergent feed periods (12,13) and in that the enzyme-containing detergency booster (5) is introduced into the wash liquor immediately after or during the interruptions or stoppage phases (11) of the operation of the dishwashing machine and/or the feed intervals (14,15) of the detergent (19).
13. A process as claimed in claim 12, characterized in that the enzyme-containing detergency booster (5) is added to the wash liquor as the enzyme is degraded or decomposed (consumed) to maintain the concentration of enzyme.
14. A process as claimed in any of the preceding claims, characterized in that, in the event of interruptions in or stoppage phases (11) of the operation of the dishwashing machine and/or intervals (14,15) in the feed of the detergent (2,19) or the detergency booster (5), the enzyme-containing detergency booster (5) undergoing enzyme degradation or enzyme decomposition (consumption) under the washing conditions prevailing in an institutional dishwashing machine (23) is added to the wash liquor in a quantity which equalizes the degradation or decomposition (consumption) of enzyme during the particular interruption or stoppage phase (11) and/or feed interval (14,15) so that, after the particular interruption or stoppage phase (11) and/or feed interval (14,15), the operation of the dishwashing machine is continued with substantially the same concentration of enzyme in the wash liquor as was present before the particular interruption or stoppage phase (11) and/or feed interval (14,15).
15. A process as claimed in any of the preceding claims, characterized in that, immediately after or during the interruptions or stoppage phases (11) and/or the feed intervals (14,15) of the detergent (2,19), the enzyme-containing detergency booster (5) is added to the wash liquor commensurately with the degradation or decomposition (consumption) of enzyme in order to maintain the enzyme concentration.
16. A process as claimed in any of claims 1 to 15, characterized in that the concentration of enzyme in the wash liquor during the particular interruption or stop-page phase (11) and/or the feed intervals (14,15) of the detergent (2,19) is maintained by maintenance feeding (17,18) of the enzyme-containing detergency booster (5).
17. A process as claimed in claim 16, characterized in that the maintenance feeding (17,18) takes place in individual feed strokes.
18. A process as claimed in claim 16 or 17, characterized in that the enzyme input rate of the maintenance feeding regime (17,18) is optimized on the basis of enzyme activity determination.
19. A process as claimed in any of claims 16 to 18, characterized in that maintenance feeding (17,18) of the enzyme-containing detergency booster (5) is commenced after the enzyme content of the wash liquor has fallen by around 20%.
20. A process as claimed in any of claims 1 to 15, characterized in that the particular interruption or stoppage phase (11) and/or feed interval (14,15) is immediately followed by surge feeding (SD) in which enzyme-containing detergency booster (5) is added to the wash liquor in a quantity corresponding to the degradation or decomposition (consumption) of enzyme which has taken place during the particular interruption or stop-page phase (11) and/or feed interval (14,15).
21. A process as claimed in claim 20, characterized in that surge feeding (SD) takes place at a constant rate over a surge feeding period (V_t) substantially equal to $${\text{V}}_{\text{t}}{\text{= V}}_{\text{max}}{\text{* (1 - e}}^{\text{-lt}}\text{)}$$

    

    where V_max is the maximum surge feeding time, λ is the reciprocal value of the time constant τ of the enzyme degradation or decomposition (consumption) and t is the duration of the interruption.
22. An arrangement for carrying out the process claimed in any of claims 1 to 21 comprising a detergent feed system (1,3;20,21,22;24,25) and a feed system (4,6;27,28) for another active substance with an associated pump (4;27) and pump control system, characterized by a feed system (4,6;27,28) for introducing an enzyme-containing detergency booster (5) which is separate from the detergent feed system (1,3;20,21,22;24,25) and which comprises an operational regime for maintenance feeding (17,18) during interruptions in or stoppage phases (11) of the operation of the dishwashing machine and/or feed intervals (14,15) of the detergent feed system (1,3;20,21,22) and/or an operational regime for surge feeding (SD) after interruptions in or stoppage phases (11) of the operation of the dishwashing machine and/or feed intervals (14,15) of the detergent feed system (24,25).
23. An arrangement as claimed in claim 22, characterized in that the detergent feed system (24,25) is operatively connected to a counter (19) which counts interval pulses during interruptions in or stoppage phases (11) of the operation of the dishwashing machine and/or feed intervals (14,15), the count (n) asymptotically approaching a predetermined end value (n_max) in steps from a starting value in accordance with a function complementary to the decomposition (consumption) of enzyme in the wash liquor, and which counts the count (n) downwards at a constant rate (R) after the particular interruption or stoppage phase (11) and/or feed interval (14,15), controlling the pump (27) for surge feeding (SD) of the enzyme-containing detergency booster (5).
24. An arrangement as claimed in claim 23, characterized in that the constant downward counting rate (r) is equal to n_max/V_max, where n_max is the maximum count and V_max is the maximum surge feeding time.
25. An arrangement as claimed in claim 24, characterized in that the constant counting rate (R) of the counter (19) is gauged in such a way that, after an interruption lasting at least 5τ (τ = consumption time constant) for the maximum surge feeding time (V_max), the enzyme concentration (C₀) prevailing before the interruption is just reached again.
26. An arrangement as claimed in any of claims 22 to 25, characterized in that the feed system (4,6;27,28) for the enzyme-containing detergency booster (5) has an additional operational regime for parallel feeding (16) which operates in parallel with the detergent feed system (1,3;24,25) when the detergent feed system is switched on.
27. An arrangement as claimed in any of claims 22 to 26, characterized in that a frequency-controlled flow inducer (4,27) or a diaphragm pump is used to feed the enzyme-containing detergency booster (5).
28. An arrangement as claimed in claim 27, characterized in that the associated frequency control system of the pump (4,27) has a first control range (I) for the maintenance feeding regime (17,18) and a second control range (II) - with a far greater output by comparison with the first control range (I) - for the wash phase (10) of the dishwashing machine when the detergent feed system is switched on.

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