Commercial dishwasher and method of operating the same

Abstract

The invention relates to a commercial dishwasher comprising a washing chamber in which at least one dispensing device for dispensing treatment liquid is arranged. The dishwasher comprises a water tank for containing treatment liquid, a first feed device for feeding raw water into the water tank, a reserve container for cleaning agent, a second feed device with a dosing pump, and a third feed device with a cleaning pump, and further comprises a conductivity sensor for determining the conductivity of the treatment liquid. The dishwasher further comprises a control device for controlling the feed of cleaning agent into the water tank by operation of the dosing pump.

Description

TECHNICAL FIELD

[0001] The present invention relates to a commercial dishwasher and to a method for operating such a commercial dishwasher. Such a commercial dishwasher comprises a washing chamber in which the items to be washed can be placed and a dispensing device for dispensing a treatment liquid or different treatment liquids. BACKGROUND

[0002] The commercial dishwasher can be, for example, a so-called automatic program machine, which comprises only one washing chamber, or a belt / basket conveyor, which comprises one washing chamber or sometimes several washing chambers.

[0003] Such a dishwasher comprises a water tank, sometimes several water tanks, for containing the treatment liquid, from which the treatment liquid can be conveyed to one or more dispensing devices for dispensing the treatment liquid into the washing chamber, wherein the treatment liquid is usually conveyed from the water tank to the dispensing device using a cleaning pump.

[0004] The treatment liquid is usually produced by supplying raw water or treated (softened, fully desalinated) water to the water tank (for example, via a connecting pipe) while also dosing cleaning agent into it via a dosing pump in order to achieve the desired concentration.

[0005] For commercial dishwashers, the dosing of the liquid cleaning agent can be carried out by different types of dosing pumps, but the so-called peristaltic pumps are often used, since these pumps are usually inexpensive and, in particular, can deliver a large amount of cleaning agent, which is particularly important for commercial dishwashers that have to deal with high throughputs and large amounts of items to be washed.

[0006] However, such dosing pumps, in particular the above-mentioned peristaltic pumps, are subject to a certain amount of wear, so that the delivery power (delivery force) decreases over time. In the case of peristaltic pumps, in particular the hose that is squeezed in the pump is subject to particular wear, which has a noticeable effect on the delivery power (delivery force).

[0007] In order to compensate for this lower delivery power, the dosing pumps have to be operated for longer (longer) and with greater intensity the longer (longer) they are operated, since otherwise the dosing (amount) of cleaning agent would be less and less, which would result in too low a concentration of cleaning agent in the treatment liquid, which in turn would have a negative effect on the cleaning of the items to be washed.

[0008] In order to ensure sufficient dosing of the cleaning agent, use is made of the fact that the concentration of cleaning agent in the raw water or treatment liquid influences the electrical conductivity of the treatment liquid, and the electrical conductivity increases with increasing concentration of cleaning agent.

[0009] Therefore, in the prior art, an electric conductivity sensor is installed in the water tank, which continuously measures the electric conductivity of the treatment liquid, wherein a control device is provided, which functions as a dosing of the cleaning agent (which causes a dosing of the cleaning agent) when the electric conductivity of the treatment liquid is lower than or falls below a predetermined value. SUMMARY

[0010] The task of the present application is to provide an improved commercial dishwasher and a method for operating such a dishwasher.

[0011] This task is solved by a commercial dishwasher according to claim 1 and a method according to claim 19. Claims 2 to 18 relate to particularly preferred embodiments of the dishwasher according to the application, and claim 20 relates to particularly preferred embodiments of the method according to the application.

[0012] The commercial dishwasher according to the application comprises a washing chamber, in which at least one dispensing device for dispensing a treatment liquid is arranged. The dishwasher according to the application further comprises:

[0013] - a water tank for containing a treatment liquid,

[0014] - a first feed device for feeding raw water into the water tank,

[0015] - a reserve container for a cleaning agent,

[0016] - a second feed device with a dosing pump, in particular a peristaltic pump, for feeding the cleaning agent from the reserve container into the water tank,

[0017] - a third feed device with a cleaning pump for feeding the treatment liquid from the water tank to the at least one dispensing device,

[0018] - an electric conductivity sensor for determining the electric conductivity of the treatment liquid.

[0019] The dishwasher according to the application further comprises a control device, which is configured to recognize whether it is a first or a subsequent activation of the dishwasher when the dishwasher is activated, and / or the dishwasher comprises a control device and an input device, via which a user can input whether it is a first or a subsequent activation, wherein the control device comprises a storage device.

[0020] According to the application, the dishwasher and the control device are configured in such a way that the electric conductivity of the raw water is measured at least at the first activation and at the subsequent activations by means of the electric conductivity sensor, and the electric conductivity of the treatment liquid after the cleaning agent has been fed to the raw water, wherein the control device determines (calculates) a correction factor KA at each activation from these measured values and a comparison of these measured values, which correction factor is related to or depends on a decrease in the delivery power of the dosing pump over the service life.

[0021] Since in such a dishwasher the conductivity of the raw water is measured at least at the first activation and the conductivity of the treatment liquid is measured at the first activation and at the subsequent activations, respectively, and under generally constant and controlled conditions, and the conductivity at one or more subsequent activations is compared with the respective measured value at the first activation, conclusions can be drawn by the control device from these values about the aging or wear of the dosing pump and about a reduction in the delivery power of the dosing pump. Thereby, the control device can calculate a correction factor which remains constant between two activations.

[0022] In the subsequent normal operation after the activation, the dosing pump, in particular the peristaltic pump, can thus be controlled completely in terms of time, depending only on the amount of raw water fed (supplied), the required cleaning agent concentration and the above-mentioned correction factor. It is not necessary to continuously measure the conductivity of the treatment liquid, and the control does not need to react continuously to changing measured conductivity values. Thus, the dishwasher adapts to the changing condition or wear of the dosing pump between two activations.

[0023] Here, the change in the delivery power of the dosing pump between two activations is deliberately accepted, since the change in the delivery power between two activations is usually very small and negligible, wherein for commercial dishwashers it is generally assumed that there is an activation approximately once a day.

[0024] Here, the dosing adapts in a simple and very reliable manner to the increased wear of the dosing pump, in particular the peristaltic pump.

[0025] This control of a commercial dishwasher has further decisive advantages: namely, the conductivity of the treatment liquid is not only influenced by the cleaning agent concentration, but also by other factors, in particular an increase in the amount of dirt (input) in the treatment liquid, a change in the raw water quality, a defect or a false operation of the dosing system, which can occur from time to time in the normal operation of the dishwasher.

[0026] If one of the factors, for example the amount of dirt (input), changes during the operation of the dishwasher, the conductivity sensor will determine the changed conductivity and thus change the dosing (use) of the cleaning agent, even if the concentration of the cleaning agent can be correct.

[0027] This not only leads to an undesirably high or undesirably low, i.e. incorrect, cleaning agent concentration, which can sometimes be significantly higher than the concentration deviation caused by the slight change or increase in wear between two activations described above, which either deteriorates the cleaning result or leads to an unnecessary high consumption of cleaning agent, which in turn increases the wear by more frequent switching on and off of the dosing pump.

[0028] Thus, the present application provides a simpler, less expensive method and a corresponding dishwasher, which still ensures the desired accuracy of the concentration of the cleaning agent in the treatment liquid, sometimes even exceeding the accuracy of significantly more cumbersome, more complex, more expensive and more delicate systems. In particular, the method and the dishwasher according to the present application are less susceptible to a significantly varying amount of dirt (input) during a wash run, which is often the case in commercial dishwashers, and the required concentration is essentially maintained at a constant or stable (unchanging) level without large fluctuations, regardless of the varying amount of dirt (input) during a wash run or during the normal operation of the dishwasher.

[0029] It is preferred that the dishwasher is designed in such a way that the amount of raw water which needs to be fed (supplied) to the tank (in order to compensate for the consumption of water or treatment liquid) during the first activation and / or during the subsequent activation and / or during the normal operation of the dishwasher is determined, in particular measured or input, or is predetermined by the volume of the tank, and that the cleaning agent is fed (supplied) by the dosing pump in accordance with the amount of raw water fed, wherein the amount fed is controlled over the period of time during which the dosing pump is operated, the length of the period of time being determined by the control device taking into account the correction factor KA. It is preferred here that, in order to control the dosing pump, in particular the duration of operation or the on duration of the dosing pump or the on and off of the dosing pump, the conductivity of the treatment liquid is not measured, or at least not transmitted to the control device, or at least not processed by the control device, during the normal operation of the dishwasher.

[0030] In a particularly preferred embodiment, the dishwasher further comprises a temperature sensor which is designed to be able to measure the temperature of the raw water and / or the treatment liquid, wherein the control device takes into account these temperatures and / or temperature differences when determining the correction factor KA. In this way, the control becomes more precise, since the conductivity depends on the temperature of the measured liquid, in particular the temperature of the raw water and the temperature of the treatment liquid. In particular in the case of different temperatures between two measurements, for example different temperatures at the first activation and at the subsequent activation, the temperature difference can be taken into account and the required concentration can be set (adjusted) more accurately. In a preferred embodiment, the temperature change or the temperature difference can also be taken into account during the normal operation in order to adjust (adapt) the dosed amount more precisely.

[0031] In another embodiment, the conductivity of the raw water is also measured at the subsequent actuation, preferably at all subsequent actuations, and is fed into the control device for determining the correction factor. In a simple embodiment, this measurement is not made, in particular if it is assumed that the quality of the raw water does not change, so that the conductivity of the raw water also remains constant over time. However, the additional measurement of the conductivity of the raw water at the subsequent actuation also increases the accuracy, in particular if there are fluctuations in the quality of the raw water. As mentioned above, if there is a temperature sensor, the temperature difference that can exist in the (each) measurement can also be compensated for by means of this measurement, in addition to or instead of the calculated compensation or the calculated adjustment or correction.

[0032] A particularly preferred and detailed embodiment of the dishwasher according to the application is described in claims 5-11, in which preferred procedures, measurements and calculations are listed in particular detail, which make the result of the dishwasher particularly reliable and the control particularly reliable and simple.

[0033] During the first actuation, the conductivity LR of the raw water is determined by means of the conductivity sensor. Then, by operating the dosing pump, the cleaning agent is fed to the water tank to produce the treatment liquid. Here, the dosing pump is operated at a constant power for a certain time, which is usually predetermined by the pump, usually at a fixed power level, in particular in the case of the peristaltic pump preferably used. The amount of cleaning agent to be dosed is therefore controlled exclusively on the basis of time, i.e. by the time (elapsed) for which the dosing pump, in particular the peristaltic pump, is operated.

[0034] This time period tx(x = 0), i.e. the time period to at the first actuation, is determined from the nominal delivery power PN of the dosing pump, the amount of raw water fed to the water tank, in particular the amount measured or input, or the volume V of the water tank and the target concentration, wherein the time period tx= to determined in this way is then stored.

[0035] The nominal power PN of the dosing pump can be the specification of the dosing pump or a starting value of the power of the dosing pump, which is determined (calculated) or assumed. Preferably, this value is also stored in the control device or the associated storage device. This power value is the starting value from which the further operation of the dishwasher begins.

[0036] At the subsequent actuations, the water tank is filled with raw water in a similar manner, a cleaning agent is dosed, and the conductivity of the treatment liquid is subsequently measured. In order to feed the cleaning agent, the dosing pump is operated for a period of time tx, x > 1. This results in a period of time ti for the first subsequent actuation after the first actuation, a period of time t2for the second subsequent actuation, and so on. Thus, the index 0 or x = 0 stands for the first actuation, and the indices 1, 2, 3, 4... or x = 1, x = 2, x = 3, etc. stand for the subsequent actuations that follow.

[0037] In order to determine the length of the period of time tx, in the case of the first subsequent actuation (i.e. ti), the period of time tx-i of the previous actuation (in this case and in the case of the first subsequent actuation thus to) is multiplied by the correction factor KAxi determined in the previous actuation (in this case KA0). Since the correction factor KA0is set to 1 at the first actuation, the duration ti at the first subsequent actuation is equal to the duration to of the first actuation.

[0038] With further subsequent actuations, the correction factor and thus the duration tx increase as a result of the increasing wear.

[0039] With regard to the conductivity LRof the raw water, it is preferred in one embodiment to use (retroactively) the conductivity determined at the first actuation. This is generally possible, since the quality of the raw water is often stable.

[0040] However, in another embodiment, in particular at the subsequent actuations, the conductivity LRof the raw water can also be determined anew each time, and the newly determined conductivity of the raw water is then used for further calculations. In this case, the value LRis replaced by the new or adjusted or corrected value LR(also referred to as LRx) in the calculation. In this way, changes in the raw water can be identified and the dishwasher can react accordingly. Changes in the raw water occur if the user changes the water source intentionally or unintentionally.

[0041] In another preferred embodiment, the dishwasher and the control device are configured to take into account a temperature T determined by a temperature sensor, and a temperature constant, and / or a cell constant Z of the conductivity sensor when determining the conductivity L of the raw water and / or of the treatment liquid. The temperature constant takes into account in particular the change in the conductivity of the liquid to be measured with the temperature. The temperature constant can be uniform for all measurements, but different temperature constants can also be used for measuring the raw water than for measuring the treatment liquid.

[0042] The cell constant is related to the properties of the conductivity sensor, and when calibrating a specific sensor, for example with a calibrated solution of known conductivity, the cell constant can be adjusted accordingly, so that the measurement result is more accurate. This does not change the accuracy of the measurement, so in both cases, whether or not calibration is carried out, whether or not the cell constant is specifically adjusted (adapted), the constancy of the measurement and thus also the constancy of the control remain at a high level.

[0043] According to a further inventive aspect independent of the above-mentioned embodiments, there is also provided a dishwasher according to claim 18, which has a washing chamber, in which at least one dispensing device for dispensing treatment liquid is arranged, the dishwasher comprising:

[0044] - a water tank for containing treatment liquid,

[0045] - a first feed device for feeding raw water into the water tank,

[0046] - a reserve container for cleaning agent,

[0047] - a second feed device with a dosing pump, in particular a peristaltic pump, for feeding cleaning agent from the reserve container into the water tank,

[0048] - a third feed device (feed device) with a cleaning pump for feeding treatment liquid from the water tank into the at least one dispensing device, and

[0049] - a conductivity sensor for determining the conductivity of the treatment liquid,

[0050] characterized in that the third feed device comprises a conduit (line / pipe) or feed section connecting the water tank with the at least one dispensing device, wherein the cleaning pump is arranged in the conduit or feed section or parts thereof and between the water tank and the dispensing device, wherein the conductivity sensor is also arranged in the conduit or feed section or parts thereof and between the cleaning pump and the dispensing device or between the feed section and the cleaning pump.

[0051] The advantage of this positioning of the conductivity sensor is that the electrodes of the conductivity sensor are constantly flushed from all sides, sometimes with a large volume flow, so that they do not become dirty and thus provide more accurate and reliable results, and in addition, the service life of the conductivity sensor is significantly increased compared to prior art devices in which the conductivity sensor itself is arranged in the water tank. This positioning also facilitates more precise measurement, due to the separation from the feed of cleaning agent (detergent) and due to the separation from the heating system.

[0052] This independent inventive positioning of the conductivity sensor can be used both for the dishwashers described above, in particular in connection with claims 1 to 12, and optionally for dishwashers described in the prior art which measure the conductivity of the treatment liquid periodically or substantially continuously. Since these dishwashers rely more significantly on the periodic and correct measurement of the conductivity, both during the normal operation of the dishwasher and between individual actuations, the positioning of the conductivity sensor according to the application is of particular importance for these dishwashers.

[0053] In a particular embodiment, the dishwasher comprises a display device which is capable of displaying the measured values of the sensors of the dishwasher, in particular of the conductivity sensor or of the temperature sensor, or of displaying values and results calculated or determined by the control device, or of displaying information input by the user or other status and data of the dishwasher. Thereby, the user is able to monitor the operating status of the dishwasher at any time and to make changes if necessary.

[0054] In a particularly preferred embodiment, the control device is configured to generate a warning signal when the correction factor KA or KAx exceeds a predetermined or adjustable value, wherein it is preferred that the dishwasher comprises a display device (indicating device) which emits a visual or acoustic signal when the predetermined or adjustable value of the correction factor KA or KAx is exceeded.

[0055] An increase in the value of the correction factor indicates an increased wear and / or a reduced delivery power of the dosing pump due to wear or other reasons, while the achievement of the predetermined or adjustable value indicates that maintenance and / or the replacement of wear parts, such as the replacement of the extruded hose in a peristaltic pump, should be considered. The display device provides the user with an early report or warning, so that he is informed in good time about the wear condition of the dishwasher, in particular of the dosing pump, and can organize the corresponding maintenance steps, such as the procurement of spare parts, in good time.

[0056] In another preferred embodiment, the dishwasher further comprises an input device by means of which a manual setting (adjustment) can be made. This makes it possible for the user to easily and at any time adjust the operation and control of the dishwasher according to his own wishes, if necessary taking into account the displayed values.

[0057] The application also relates to a method for operating such a commercial dishwasher, for which reference is made to the explanations above regarding the advantages and particular aspects. BRIEF DESCRIPTION OF DRAWINGS

[0058] Further features and advantages of the dishwasher according to the application and of the method according to the application will become more apparent after reference has been made to the following drawings:

[0059] Figure 1 The structure of one embodiment of a dishwasher according to the application is shown schematically, and

[0060] Figure 2 A flow chart according to an embodiment of the application is schematically shown. DETAILED DESCRIPTION

[0061] Figure 1 A structure of a dishwasher 10 according to an embodiment of the application is schematically shown, which dishwasher comprises a washing chamber 20 with a plurality of dispensing devices 110 for dispensing treatment liquid into the washing chamber 20, wherein in this embodiment two upper and two lower dispensing devices are provided, which are arranged rotatably. Between the upper and lower dispensing devices 110, a washing basket 120 for accommodating the dishes to be cleaned is schematically shown.

[0062] The dishwasher 10 comprises a water tank (box) 200 with a heater 210 for accommodating treatment liquid. The water tank 200 can be filled with raw water by means of a first feeding device (first supply device) 250.

[0063] Furthermore, the dishwasher 10 comprises a reserve container 300 for cleaning agent, which can be dosed from the reserve container 300 into the water tank by means of a second feeding device 330, which comprises a dosing pump 320, here a peristaltic pump.

[0064] The dishwasher 10 further comprises a third feeding device 230 with a cleaning pump 220, by means of which treatment liquid can be fed from the water tank 200 to the dispensing devices 110.

[0065] An electrical conductivity sensor 240 is provided in the third feeding device 230 and downstream of the cleaning pump 220 in the flow direction, which can measure the electrical conductivity of the treatment liquid. The electrical conductivity sensor 240 is connected to the control device 500, so that the measurement values of the electrical conductivity sensor 240 can be transmitted to the control device 500, wherein the control device 500 comprises a memory, so that the measurement results or other data information of the electrical conductivity sensor 240 can be stored.

[0066] The dishwasher further comprises an input device 800, by means of which the user can input data and information. For example, the user can explicitly input that after the activation of the dishwasher a first activation should take place, or it can also be specified that a subsequent activation is intended. The control device can also be designed, for example, such that as soon as no explicit external input from the user is made that this is a first activation, it is always assumed that a new activation is a subsequent activation, or the control device automatically recognizes this, for example because a replacement of the dosing pump has been recognized.

[0067] In a particular embodiment, the dishwasher further comprises a display device 820. The display device can display certain modes or operating data (running data) of the dishwasher to the user, or it can also display certain measurement values.

[0068] Thereby, the user has a good overview of the operating state of the dishwasher and, if necessary or desired, he can also input changes, for example manual correction factors, via the input device 800, as described above.

[0069] Furthermore, the dishwasher 10 also comprises a drain 630 in which an alkali pump (alkali wash pump) 600 is arranged in order to take up and carry away (remove) the treatment liquid, in particular the dirty treatment liquid, from the water tank 200.

[0070] The embodiment of the dishwasher 10 also comprises a boiler 400 with a heater 410 for containing a rinse liquid. The rinse liquid can be guided to the dispensing device 110 by a further supply device 430 in which a rinse pump 420 is arranged.

[0071] The boiler (steam heater) 400 is supplied by a supply device 440 for supplying raw water, in which a reserve container 450 for clean detergent is also arranged, which is dosed by a dosing pump 460.

[0072] Figure 2 The flow chart according to the application is shown in the form of a schematic diagram:

[0073] Step S is the activation of the dishwasher, in which step B the control device detects whether it is the first activation (or a reset of the system). As described above, the user can also input that it is the first activation, for example.

[0074] If "yes", step N is the filling of the water tank with raw water, the measurement of the electrical conductivity of the raw water with the conductivity sensor, the feeding (adding) of the cleaning agent, the measurement of the electrical conductivity of the treatment liquid thus produced, the calculation of the difference in electrical conductivity and the storage of these data.

[0075] In a further step, the correction value KAo is set to 1, as described above.

[0076] If "no", as step X the water tank is filled with raw water, in which embodiment the electrical conductivity of the raw water is also measured by the conductivity sensor (although in another embodiment the electrical conductivity of the raw water can not be measured at this time, but the value already measured at the first activation can be used), the feeding (adding) of the cleaning agent, the measurement of the electrical conductivity of the treatment liquid thus produced, the calculation of the difference in electrical conductivity and the storage of these data.

[0077] In a subsequent step, the new correction factor KA is calculated, as described above.

[0078] According to the calculation result and the current correction factor, the normal operation of the dishwasher is now started, and the control device controls the dishwasher, in particular the dosing of cleaning agent, by controlling the operating time of the dosing pump, in particular in dependence on the determined value, in particular the determined correction factor KA x.

[0079] These and other features of the present application, either alone or in any combination, can be essential to the realization of the present application.

Claims

1. A commercial dishwasher, comprising a washing chamber in which at least one dispensing device for dispensing a treatment liquid is arranged, wherein The dishwasher further comprises - a water tank for containing the treatment liquid, - a first feed device for feeding raw water into the water tank, - a reserve container for cleaning agent, - a second feed device with a dosing pump for feeding cleaning agent from the reserve container into the water tank, - a third feed device with a cleaning pump for feeding treatment liquid from the water tank to the at least one dispensing device, and - an electrical conductivity sensor for determining the electrical conductivity of the treatment liquid, characterized in that the dishwasher comprises a control device which is configured to recognize, when the dishwasher is activated, whether it is the first activation or a subsequent activation, and / or the dishwasher comprises a control device and an input device by means of which a user can input whether it is the first activation or a subsequent activation, wherein the control device comprises a storage device, wherein the dishwasher and the control device are configured to measure, by means of the electrical conductivity sensor, the electrical conductivity of the raw water at least at the first activation and the electrical conductivity of the treatment liquid after the cleaning agent has been fed into the raw water at the first activation and at the subsequent activation, wherein the control device determines a correction factor KA at each activation from these measured values and a comparison of these measured values, which correction factor is related to a decrease in the delivery power of the dosing pump over the service life.

2. The dishwasher according to claim 1, characterized in that The dosing pump is a peristaltic pump.

3. The warewashing machine of claim 1, wherein, The dishwasher is designed such that, at the first activation and / or at the subsequent activation and / or during normal operation of the dishwasher, the amount of raw water fed into the water tank is determined or is predetermined by the volume of the water tank, and the cleaning agent is fed by means of the dosing pump in dependence on the amount of raw water fed, wherein the amount fed is controlled over the length of a time period in which the dosing pump is operated, wherein the length of the time period is determined by the control device taking into account the correction factor KA.

4. The warewashing machine of claim 3, wherein, The amount of raw water fed into the water tank is measured or input.

5. The dishwasher according to any one of claims 1 to 4, characterized in that The dishwasher further comprises a temperature sensor which is designed such that it can measure the temperature of the raw water and / or of the treatment liquid, wherein the control device is designed to take into account the temperature and / or a temperature difference when determining the electrical conductivity and / or when determining the correction factor KA.

6. The warewash machine of any of claims 1-4, wherein, The electrical conductivity of the raw water is also measured at the subsequent activation and is fed to the control device for determining or changing the correction factor.

7. The warewash machine of any of claims 1-4, wherein, The electrical conductivity of the raw water is also measured at all subsequent activations and is fed to the control device for determining or changing the correction factor.

8. The dishwasher as claimed in claim 1, characterized in that the second feed device has a nominal delivery power PN, the control device is configured to recognize, when the dishwasher is activated, whether it is the first activation or the xth subsequent activation, x > 1, and / or the dishwasher comprises a control device and an input device by means of which a user can input whether it is the first activation or a subsequent activation, wherein the control device is configured, when the dishwasher is activated, to perform the following steps if the control device recognizes that it is the first activation and / or if the first activation is input by means of the input device: - filling the water tank with raw water, wherein the amount of raw water VN fed into the water tank during the use is determined or is given in advance by the volume of the water tank, - measuring and storing the conductivity LR of the raw water by means of the conductivity sensor, - feeding a cleaning agent into the water tank by operating the dosing pump in a time period tx at x = 0 to produce the treatment liquid, wherein the control device determines the time period tx at x = 0 from a nominal delivery power PN of the dosing pump, a quantity VN of raw water filled into the water tank and a target concentration C 目标 determining the time period tx at x = 0 and storing the time period tx at x = 0, - measuring and storing the conductivity LN of the treatment liquid, - determining and storing the difference in conductivity ΔLN, wherein ΔLN = LN - LR, - setting the correction factor KA x for x = 0 to a value of 1 and storing it, wherein the control device is configured to, upon use of the dishwasher, in the case where the control device recognizes a subsequent use and / or where there is no input by the input device that it is a first use and / or where there is an input by the input device that it is a subsequent use, carry out the following steps: - filling the water tank with raw water, wherein the amount of raw water Vx fed into the water tank during the use is determined or is given in advance by the volume of the water tank, - feeding the cleaning agent into the water tank by operating the dosing pump over a period of time tx to produce the treatment liquid, wherein the period of time tx is determined by the control device by multiplying the stored period of time tx-1 by the stored correction factor KA x-1 and from the amount of raw water fed into the water tank in accordance with the following equation, wherein x > 1, - measuring and storing the conductivity Lx of the treatment liquid, - determining and storing the difference in conductivity ΔLx, wherein ΔLx = Lx - LR, - setting and storing a new correction factor KA x, wherein the new correction factor KA x is determined in accordance with the following equation:

9. The warewash machine of claim 8, wherein, The dosing pump is a peristaltic pump.

10. The warewashing machine of claim 8, wherein, In the case where the control device recognizes a first use and / or where there is an input by the input device that it is a first use, the amount of raw water VN fed into the water tank during the use is measured or input.

11. The warewash machine of claim 8, wherein, In the case where the control device recognizes a subsequent use and / or where there is no input by the input device that it is a first use and / or where there is an input by the input device that it is a subsequent use, the amount of raw water Vx fed into the water tank during the use is measured or input.

12. The warewash machine of claim 8, wherein, The control device is configured to, upon use of the dishwasher, in the case of a subsequent use, after the step of filling the water tank with raw water, carry out the following steps: - re-measuring and storing the conductivity LR of the raw water by means of the conductivity sensor, wherein, in the step of determining and storing the difference in conductivity ΔLx, the conductivity LR of the raw water, which is determined anew upon a subsequent use, is taken into account, wherein ΔLx = Lx - LR.

13. The dishwasher according to any one of claims 8 to 12, characterized in that The period of time tx in which the cleaning agent is fed is additionally determined in accordance with the following equation in consideration of a manual correction factor KMx and is then stored: t x = t0 x KA x-1 x KM x .

14. The warewash machine of claim 13, wherein, The manual correction factor KMx can be input or selected by a user or a technician via the input device of the dishwasher.

15. The warewash machine of any of claims 8-12, wherein, the amount V of raw water fed into the water tank during normal operation 填充 is determined and a cleaning agent is fed by means of the dosing pump operating over a time period tdx, which is determined by the control device on the basis of the amount V of raw water fed 填充 , the target concentration C 目标 , the nominal delivery power PN of the dosing pump and the correction factor KAx are determined in accordance with the following formula:

16. The warewash machine of claim 15, wherein, The amount V of raw water fed to the water tank during normal operation 填充 is measured or input.

17. The warewash machine of any of claims 8-12, wherein, the amount V of raw water fed into the water tank during normal operation 填充 is determined and a cleaning agent is fed by means of the dosing pump operating over a time period tdx, which is determined by the control device on the basis of the amount V of raw water fed 填充 , the target concentration C 目标 , the nominal delivery power PN of the dosing pump, the correction factor KAx and the manual correction factor KMx are determined in accordance with the following formula:

18. The warewash machine of claim 17, wherein, The amount V of raw water fed to the water tank during normal operation 填充 is measured or input.

19. The warewash machine of claim 17, wherein, The manual correction factor KMx can be input or selected by a user or a technician via the input device of the dishwasher.

20. The warewash machine of any of claims 8-12, wherein, The dishwasher further comprises at least one temperature sensor for determining the temperature of the raw water and / or the treatment liquid.

21. The warewash machine of claim 20, wherein, The temperature of the raw water and / or of the treatment liquid determined by the temperature sensor is taken into account as a correction factor when determining the conductivity of the raw water and / or of the treatment liquid and / or when comparing the determined conductivities.

22. The warewash machine of claim 20, wherein, The dishwasher and the control device are configured such that, when determining the conductivity L of the raw water and / or of the treatment liquid, the temperature T determined by the temperature sensor and a temperature constant and / or a cell constant Z of the conductivity sensor are taken into account, wherein the conductivity L is calculated according to the following formula: where G is the conductance value measured by the conductivity sensor, and σ T is a temperature constant that is either universal or specific to the processing medium.

23. The warewash machine according to any of claims 8-12, wherein, The third feed device comprises a conduit or feed connecting the water tank to the at least one dispensing device, wherein the cleaning pump is arranged within the conduit or feed and between the water tank and the dispensing device, wherein the conductivity sensor is also arranged within the conduit or feed and either between the cleaning pump and the dispensing device or between the water tank and the cleaning pump.

24. The warewash machine according to any of claims 8-12, wherein, The dishwasher comprises a display device which can display the measured values of the sensors of the dishwasher, or which can display the values and results calculated or determined by the control device, or which can display information input by the user or other states and data of the dishwasher.

25. The warewash machine of claim 24, wherein, The display device can display the measured values of the conductivity sensor or of the temperature sensor.

26. The warewash machine according to any of claims 8-12, wherein, The control device is configured to generate a warning signal when the correction factor KA or KAx exceeds a predetermined value or an adjustable value.

27. The warewash machine of claim 26, wherein, The dishwasher comprises a display device which emits a visual signal or an acoustic signal when the predetermined value or the adjustable value of the correction factor KA or KAx is exceeded.

28. The warewash machine according to any of claims 8-12, wherein, The dishwasher comprises an input device by means of which a manual adjustment can be made, or by means of which values and / or corrections and / or correction values can be input, which the control device can use for controlling the dishwasher.

29. The warewash machine according to any of claims 8-12, wherein, Said dishwashing mechanism is configured to adjust said target concentration to a value C after first activation 目标x In this case the correction factor KAx is multiplied by an additional adjustment factor C 目标x / C 目标 .

30. The dishwasher as claimed in claim 1, characterized in that The third feed device comprises a conduit or feed connecting the water tank to the at least one dispensing device, wherein the cleaning pump is arranged within the conduit or feed and between the water tank and the dispensing device, wherein the conductivity sensor is also arranged within the conduit or feed and either between the cleaning pump and the dispensing device or between the water tank and the cleaning pump.

31. The warewash machine of claim 30, wherein, The dosing pump is a peristaltic pump.

32. A method for operating a commercial dishwasher as claimed in any of claims 1 to 31, the dishwasher having a wash chamber and a dispensing device for dispensing a treatment liquid, characterized in that The dishwasher comprises a control device which recognizes whether it is a first activation or a subsequent activation when the dishwasher is activated, and / or the dishwasher comprises an input device by means of which a user can input a first activation or a subsequent activation, wherein the conductivity of the raw water is measured by the conductivity sensor at first activation and at subsequent activations and the conductivity of the treatment liquid after feeding of a cleaning agent into the raw water, wherein the control device determines a correction factor KA at each activation from these measured values and a comparison of these measured values, which correction factor is related to a decrease in the delivery power of the dosing pump over the service life.

33. The method of claim 32, wherein, The amount of raw water fed into the water tank is determined, or is given in advance by the volume of the water tank, during first activation and / or during subsequent activation and / or during normal operation of the dishwasher, and the cleaning agent is fed by the dosing pump as a function of the amount of raw water fed, wherein the amount fed is controlled over the length of the time period during which the dosing pump is operated, wherein the length of the time period is determined by the control device taking into account the correction factor KA.

34. The method of claim 33, wherein, The amount of raw water fed into the water tank is measured or input during first activation and / or during subsequent activation and / or during normal operation of the dishwasher.

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