SYSTEM FOR MONITORING THE OPERATION OF A COMMERCIAL DISHWASHER, DISHWASHER AND METHOD FOR MONITORING THE OPERATION OF A DISHWASHER

Abstract

A system for monitoring the operation of a commercial dishwasher (2), which is embodied as a box-type dishwasher or as a conveyor dishwasher, includes at least one temperature sensor (60) designed to record a temperature profile with respect to time which corresponds to the temperature profile with respect to time to which an item of washware is subjected when it is treated in the dishwasher (2). The system further includes an evaluation device (62) designed to receive and to evaluate the temperature profile recorded by the at least one temperature sensor (60), wherein the evaluation device (62) is further designed to ascertain a value of a notional unit of quantity of heat from the temperature profile recorded by the temperature sensor (60). A dishwasher (2) including a corresponding monitoring system and a method for monitoring the operation of a dishwasher (2) are also provided.

Claims

1. A system for monitoring the operation of a commercial dishwasher (2) which is embodied as a box-type dishwasher or as a conveyor dishwasher, wherein the system comprises the following: at least one temperature sensor (60) which is designed to record a temperature profile with respect to time which corresponds to the temperature profile with respect to time to which an item of washware is subjected when it is treated in the dishwasher (2); and an evaluation device (62) which is designed to receive and to evaluate the temperature profile recorded by the at least one temperature sensor (60), wherein the evaluation device (62) is further designed to ascertain a value of a notional unit of quantity of heat from the temperature profile recorded by the temperature sensor (60).

2. The system as claimed in claim 1, wherein the evaluation device (62) is designed to extract a temperature value from the temperature profile recorded by the at least one temperature sensor (60) at previously defined or definable measurement points and to ascertain an equivalent value of a quantity of heat from the extracted temperature value in accordance with a previously defined or definable assignment.

3. The system as claimed in claim 2, wherein the evaluation device (62) is designed to form a sum of the equivalent values of the quantities of heat from measurement points of the temperature profile for ascertaining the value of the notional unit of quantity of heat.

4. The system as claimed in claim 1, wherein the evaluation device (62) is designed to compare the ascertained value of the notional unit of quantity of heat with a previously defined setpoint value and to output a corresponding warning and/or message when the ascertained value of the notional unit of quantity of heat falls below the setpoint value.

5. The system as claimed in claim 1, wherein the system further has at least one write/read unit (61, 63) for wirelessly transmitting data and/or commands between the at least one temperature sensor (60) and the evaluation device (62).

6. The system as claimed in claim 5, wherein the at least one write/read unit (61, 63) is designed to automatically read out the temperature profiles and/or the data which corresponds to the temperature profiles from the temperature sensor (60) following completion of recording of n whole-number temperature profiles, where n>1.

7. The system as claimed in claim 6, wherein the at least one write/read unit (61, 63) has an interface for automatically transmitting data read out from the temperature sensor (60).

8. The system as claimed in claim 1, wherein the at least one temperature sensor (60) is attached to a measurement body and/or item of washware or is integrated in a measurement body and/or item of washware.

9. A commercial dishwasher (2), which is embodied as a conveyor dishwasher or as a box-type dishwasher and has at least one treatment chamber or treatment zone (10, 12, 14, 16, 18) in which wash liquid and/or final rinse liquid is at least temporarily sprayed onto washware to be treated, wherein the dishwasher (2) has at least one system as claimed in claim 1 for continuously monitoring the operation of the dishwasher (2).

10. The dishwasher (2) as claimed in claim 9, which is embodied as a conveyor dishwasher and has a conveyor device (4) for conveying washware through the at least one treatment zone (10, 12, 14, 16, 18) of the dishwasher (2), wherein the at least one temperature sensor (60) of the monitoring system is connected or can be connected to the conveyor device (4) or is integrated in the conveyor device (4) in such a way that, as the washware is conveyed, the at least one temperature sensor (60) is likewise conveyed through the at least one treatment zone (10, 12, 14, 16, 18) of the dishwasher (2).

11. The dishwasher (2) as claimed in claim 10, wherein an inlet region (11) in which at least one write/read unit (61, 63) of the monitoring system is arranged is provided in front of the at least one treatment zone (10, 12, 14, 16, 18) as seen in the conveying direction (8) of the washware.

12. The dishwasher (2) as claimed in claim 9 to 11, wherein the dishwasher (2) is designed to treat the washware to be treated in the at least one treatment chamber or treatment zone (10, 12, 14, 16, 18) in a state in which the said washware is held in a dish rack, wherein the at least one temperature sensor (60) of the monitoring system is connected or can be connected to the dish rack or is integrated in the dish rack.

13. The dishwasher (2) as claimed in claim 9, which further has a control device (50) for adjusting a temperature of the wash and/or final rinse liquid to be sprayed in the at least one treatment chamber or treatment zone (10, 12, 14, 16, 18) of the dishwasher (2) and/or for adjusting an action time of the washware to be treated in the at least one treatment chamber or treatment zone (10, 12, 14, 16, 18), wherein the control device (50) is designed to preferably automatically adjust, in particular to regulate, the temperature of the wash and/or final rinse liquid to be sprayed in the at least one treatment chamber or treatment zone (10, 12, 14, 16, 18) and/or the action time of the washware to be treated in the at least one treatment chamber or treatment zone (10, 12, 14, 16, 18) depending on a value of the notional quantity of heat ascertained using the evaluation device (62).

14. The dishwasher (2) as claimed in claim 13, wherein the control device (50) is designed to store and/or to document the value of the notional quantity of heat ascertained during operation of the dishwasher (2) for each cycle or unit of time, in particular for documentation reasons.

15. A method for monitoring the operation of a commercial dishwasher (2), in particular a dishwasher (2) as claimed in claim 9, wherein a temperature profile with respect to time is recorded during operation of the dishwasher (2), the said temperature profile with respect to time corresponding to the temperature profile with respect to time to which an item of washware is subjected when it is treated in the dishwasher (2), and wherein a value of a notional unit of quantity of heat is ascertained from the recorded temperature profile.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In the following text by referring to the accompanying drawings, an exemplary embodiment of the dishwasher according to the invention will be described in more detail.

[0063] Shown are:

[0064] FIG. 1 an example mapping for determining an equivalent value of the quantity of heat at a corresponding temperature value;

[0065] FIG. 2 a schematic graphical representation for explaining the relationship between time and temperature to obtain 3,600 HUE values during a treatment in a dishwasher; and

[0066] FIG. 3 a schematic representation of an exemplary embodiment of the dishwasher according to the invention with integrated monitoring system.

DETAILED DESCRIPTION

[0067] Before an exemplary embodiment of the present invention is described with reference to the schematic diagram according to FIG. 3, the hygiene-relevant temperatures to be monitored with the monitoring system will be discussed in more detail, namely using the example of the NSF requirements.

[0068] The thermal process of “hot-water sanitization” defined in the NSF describes a method in which a minimum number of 3,600 heat units (HUE units) should be measured on the surfaces of the washware. In this method described in the NSF, temperature sensors are mounted on three dinner plates. These three plates are washed according to the method described in the NSF and the temperature on them is recorded during the entire program cycle. Heat units are counted per unit of time in seconds according to the temperature profile and added. At the end of the process, in accordance with the NSF, 3,600 NSF-values should have been obtained.

[0069] FIG. 1 shows a mapping from the temperature (in Fahrenheit) to the corresponding HUE-values in accordance with the NSF directive.

[0070] For example, if the temperature of 150° F. (corresponding to 65.6° C.) is measured at a measurement point, this corresponds to an HUE-value of 6.5.

[0071] Each temperature recorded per unit of time in seconds is assigned a corresponding HUE-value and the HUE-values accumulated during the entire processing sequence are then added. If a certain number of HUE values, such as 3,600 HUE values, are achieved at the end, the hygiene-relevant temperatures in the dishwasher are compliant with NSF/ANSI 3.

[0072] The critical 3,600 HUE values can thus be achieved if relatively high temperatures are used for a relatively short time during the washing and/or rinsing process, or if relatively low temperatures are used for a relatively long time. This relationship of time and temperature in order to achieve the required 3,600 HUE-values is shown in FIG. 2.

[0073] In the following text, by referring to the drawing in FIG. 3 an exemplary embodiment of the conveyor dishwasher according to the invention will be described in more detail. Although this embodiment involves a conveyor dishwasher, it should be noted that this is not to be regarded as restrictive. Instead, the monitoring system according to the invention can also be used in a programmable box-type dishwasher, in particular a commercial dishwasher.

[0074] Specifically, FIG. 3 schematically illustrates a conveyor dishwasher 2 with a conveyor device 4 for conveying washware, not depicted, in a conveying direction 8 through the conveyor dishwasher 2. The conveyor dishwasher 2 has at least one washing zone, for example as shown in FIG. 3, a pre-wash zone 12 and a main wash zone 14, which seen in the conveying direction 8 is arranged after the pre-wash zone 12.

[0075] As seen in the conveying direction 8, after the at least one wash zone 12, 14 a post-wash zone 16 (or pumped final rinse zone) and after the post-wash zone 16 at least one final rinse zone (or fresh water final rinse zone) is arranged, for example only one single final rinse zone 18 as shown. In the conveyor dishwasher 2 shown in FIG. 3 the final rinse zone 18 is followed in the conveying direction 8 of the washware by a drying zone 40. The respective zones 12, 14, 16, 18, 40 of the conveyor dishwasher 2 can be separated via partition curtains 47. In the embodiment shown in FIG. 3 the inlet tunnel 10 itself is also separated from the inlet 11 by a partition curtain 47. The provision of the partition curtains 47 prevents excess spraying of wash liquid and final rinse liquid and the escape of steam from the conveyor dishwasher 2.

[0076] The above-mentioned treatment zones 12, 14, 16, 18 of the conveyor dishwasher 2 are assigned spray nozzles 20, 22, 24, 26, 28, 30. These spray nozzles 20, 22, 24, 26, 28, 30 are used to spray liquid onto the washware when this is being conveyed by the conveyor device 4 through each of the treatment zones 12, 14, 16, 18. The individual spray systems of the treatment zones 12, 14, 16, 18 ensure that the washware to be treated is sprayed from both the top and the bottom.

[0077] In the conveyor dishwasher 2 schematically shown in FIG. 3, however, the final rinse zone 18 has not only downwards directed upper spray nozzles 20 and upwards directed lower spray nozzles 22, but also transversely directed lateral spray nozzles 24 on each side of the conveyor device 4. The use of lateral spray nozzles 24 allows a precise spraying of the washware surfaces (surfaces of the dishes) with final rinse liquid, even in obscured zones. In particular in a fully loaded conveyor system, i.e. when the dish rack is loaded plate to plate, the use of lateral nozzles 24 in the final rinse zone 18 has a clear advantage with regard to the final rinse result (effective rinsing of cleaner residues off the washware surfaces even in obscured zones), compared to systems in which in the final rinse zone 18 only upper and lower nozzles 20, 22 are provided, but no cross-directed lateral spray nozzles 24.

[0078] The post-wash zone 16, main wash zone 14 and pre-wash zone 12 are also assigned tanks (post-wash tank 32, main wash tank 34, pre-wash tank 36) for collecting sprayed liquid and/or for providing liquid for the spray nozzles 26, 28, 30 of the relevant treatment zones 14, 16, 18.

[0079] As already indicated, in the conveyor dishwasher 2 shown in FIG. 3, final rinse liquid, which is composed of fresh water with added rinse aid, is sprayed onto the washware, not shown, via the spray nozzles 20, 22, 24 arranged above and below the conveyor device 4 and laterally positioned in the final rinse zone 18. A part of the sprayed final rinse fluid is conveyed via a cascade system against the transport direction 8 of the washware from treatment zone to treatment zone. The remainder of the final rinse liquid sprayed in the final rinse zone 18 is directed via a valve V1 and a bypass pipe 38 directly into the pre-wash tank 36 assigned to the pre-wash zone 12.

[0080] In the cascade system the final rinse liquid sprayed by the final rinse nozzles 20, 22, 24 flows under gravity from the final rinse zone 18 into the post-wash tank 32 assigned to the post-wash zone 16. The final rinse liquid which is sprayed in the final rinse zone 18 and captured by the post-wash tank 32 is then pumped by means of a post-wash pump 45 to the spray nozzles (post-wash nozzles 26) of the post-wash zone 16.

[0081] In the post-wash zone 16, wash liquid is rinsed off the washware. The resulting liquid (post-wash liquid) flows under gravity into the main wash tank 34 assigned to the main wash zone 14. A drainage element 39, such as a drain floor or a baffle plate, is preferably provided which directs the post-wash liquid sprayed by the washer nozzles 26 into the main wash tank 34. In accordance with another embodiment, not shown, the drainage element 39 can be omitted if the main wash tank 34 extends below the post-wash nozzles 26 of the post-wash zone 16.

[0082] The liquid collected by the main wash tank 34 of the main wash zone 14 usually has a washing chemical added to it in the form of a cleaning agent (detergent), and with the aid of a main wash pump 35 is sprayed onto the washware via the spray nozzles (main wash nozzles 28) of the main wash zone 14. The wash liquid sprayed with the main washer nozzles 28 flows into the main wash tank 34 under gravity.

[0083] The main wash tank 34 is fluidically connected via an overflow pipe 37 to the pre-wash tank 36 associated to the pre-wash zone 12. Via this overflow pipe 37, the wash liquid sprayed in the main wash zone 14 arrives in the pre-wash tank 36 if a sufficient quantity of wash liquid is collected in the main wash tank 34.

[0084] The liquid collected in the pre-wash tank 36 of the pre-wash zone 12 is then sprayed onto the washware by means of a pre-wash pump 33 via the spray nozzles (prewash nozzles 30) of the pre-wash zone 12, in order to remove coarse dirt from the washware. The wash liquid sprayed with the pre-wash nozzles 30 flows into the pre-wash tank 36 under gravity.

[0085] The pre-wash tank 36 is provided with an overflow line 31, which is used to drain away the excess quantity of liquid to a waste water network, if a maximum fluid level in the pre-wash tank 36 is exceeded.

[0086] As already indicated, the liquid sprayed in the main wash zone 14 and in the pre-wash zone 12 contains a wash chemical in the form of a cleaning agent (detergent). This wash chemical is added as required to the liquid collected in the main wash tank 34 of the main washing zone 14 by means of a cleaning agent dosing device.

[0087] The cleaning agent dosing device has a corresponding 51 dosing pump, whose inlet side is flow-connected to a reservoir 52 for wash chemicals. On the pressure side the dosing pump 51 is connected to the main wash tank 34. The dosing pump 51 of the cleaning agent dosing device is preferably embodied as a controllable dosing pump 51. For this purpose the dosing pump 51 is connected via a control bus or similar (wired or wireless) control line to the control device 50 of the conveyor dishwasher 2.

[0088] As already mentioned, the final rinse zone 18 directly follows the drying zone 40 in the conveying direction 8. In the drying zone 40 the washware is dried with dry warmed air to blow away or dry off the moisture on the washware. To keep the moisture content of the air within a favorable range for drying, it is possible to supply external air to the drying zone 40, for example, via an opening, for instance through the outlet opening for the washware.

[0089] The warm and moist air in the drying zone 40 is then extracted from the drying zone 40, for example by means of a blower 41, through a further opening. It is advantageous in this case if the stream of exhaust air from the drying zone 40 passes through a device 42 for heat recovery, in which for example a condenser can be provided. The device 42 for heat recovery is used to recover at least a portion of the heat energy contained in the exhaust air.

[0090] If before the conveyor dishwasher 2 is first started the tanks assigned to the wash zones 12, 14 and 16 (pre-wash tank 36, main wash tank 34, post-wash tank 32) are empty or only insufficiently filled, these must first be filled via a fresh water pipe 90 and/or by spraying final rinse liquid in the final rinse zone 18. The fresh water pipe 90 can be connected via a controllable valve V3 to a fresh water supply network. The quantity of wash liquid available in the main washing zone 14 and in the pre-wash zone 12 can be monitored in each case by means of a level sensor provided in the main wash tank 34 or by means of a level sensor provided in the pre-wash tank 36, and notified to a control device 50.

[0091] The final rinse zone 18, may—as shown in FIG. 3—be assigned a fresh water reservoir 30 for the temporary storage of at least a portion of the fresh water used for the final rinse. The fresh water reservoir 30 is provided, on the one hand, with a fresh water connection which can be connected via a controllable fresh water supply valve V2 to a fresh water supply network, and on the other hand connected on the inlet side to a final rinse pump 43. Of course, it is also conceivable to dispense with a fresh water reservoir 30 for temporary storage of at least a portion of the fresh water provided for the final rinse and to connect the fresh water supply valve V2 directly to the inlet side of the final rinse pump 43.

[0092] The pressure side of the final rinse pump 43 is connected via a pipe system to a water heater 9. The pipe system is embodied in such a way that the liquid pumped by the final rinse pump 43 to the spray nozzles 20, 22, 24 of the final rinse zone 18 first passes through the device 42 for heat recovery before it reaches the water heater 9. In this way it is possible to use at least a portion of the thermal energy of the discharged exhaust air for heating up the liquid supplied to the spray nozzles 20, 22, 24 of the final rinse zone 18.

[0093] The fresh water supplied to the final rinse pump 43 either directly from the fresh water supply valve V2 or from the fresh water reservoir 30 is dosed with rinse aid by means of a rinse aid dosing device. The rinse aid dosing device has a (rinse aid) dosing pump 57 and a rinse aid reservoir 58. In a particularly preferred manner the rinse aid dosing pump 57 is arranged in such a way that the addition of rinse aid to the fresh water takes place at a position in which the fresh water was not yet been heated. Studies have shown that a much better and more uniform mixing of the rinse aid with the fresh water occurs when the rinse aid is added to unheated fresh water. In particular, the addition of rinse aid should be carried out in fresh water which has a temperature of less than 40° C., and preferably less than 30° C.

[0094] Therefore, in the embodiment of the conveyor dishwasher 2 shown in FIG. 3 the rinse aid dosing takes place between the final rinse pump 43 and the water heater 9 or the device 42 for heat recovery. For this purpose a supply pipe is provided which discharges in the pipe system between the final rinse pump 43 and the device 42 for heat recovery, and which is connectable via the dosing pump 57 to the rinse aid reservoir 58.

[0095] Like the dosing pump 51 of the cleaning agent dosing device, the rinse aid dosing pump 57 is preferably also connected via a suitable control bus to the control device 50 of the conveyor dishwasher 2, so that the rinse aid dosing pump 57 can also be correspondingly activated via the control device 50.

[0096] In the conveyor dishwasher 2 shown in FIG. 3 the above-mentioned control device 50 is only indicated schematically. The control device 50 to automatically adjust a final rinse liquid quantity to be sprayed per unit of time in the final rinse zone 18 and/or for automatically adjusting a wash liquid quantity to be sprayed per unit of time in the main wash zone 14. Preferably, the control device 50 is designed to control the different controllable components of the conveyor dishwasher 2, such as the individual pumps and valves, in accordance with a pre-defined or pre-definable program sequence, so as to control the process parameters in the individual treatment zones 12, 14, 16, 18 of the conveyor dishwasher 2, and in particular to allow the process parameters in the final rinse zone 18 and/or in the main wash zone 14 to be adjusted.

[0097] Also, the control device 50 is preferably designed to adjust the temperature of the final rinse liquid to be sprayed in the final rinse zone 18 and/or the temperature of the wash liquid to be sprayed in the main wash zone 14.

[0098] It is also advantageous if the control device 50 is designed to control the conveyor device 4 to adjust a specific conveying speed of the washware to be treated, and thus the action time of the washware in the individual treatment zones of the dishwasher 2.

[0099] The dishwasher 2 represented schematically in FIG. 3 is characterized by the fact that a monitoring system for monitoring the operation of the dishwasher 2 is provided. Specifically, the purpose of the monitoring system is to monitor continuously during the operation of the dishwasher 2 whether the hygiene-relevant temperatures in the individual treatment zones of the dishwasher 2 are complied with.

[0100] For this purpose, the monitoring system integrated in the dishwasher 2 has at least one temperature sensor 60 which is designed, or used, to record a temperature profile with respect to time, which corresponds to the temperature profile with respect to which an item of washware is subjected when it is treated in the individual treatment zones of the dishwasher 2.

[0101] For example, the at least one temperature sensor 60 of the monitoring system is or can be connected to the conveyor device 4 of the dishwasher 2 in such a way or be integrated in the conveyor device 4 in such a way that as the washware is conveyed the at least one temperature sensor 60 is also conveyed through the at least one treatment zone of the dishwasher 2.

[0102] The at least one temperature sensor 60 is assigned a storage unit, in which the time-temperature profile recorded by the temperature sensor 60 is temporarily stored. In this way, it is possible that after the passage of the at least one temperature sensor 60 through the treatment zones, or at least through a portion of the treatment zones, the recorded time-temperature profile can be read out from the storage unit assigned to the temperature sensor 60.

[0103] The readout of the data from the temperature sensor 60 is preferably carried out with a read/write unit 61 provided on the outlet tunnel of the conveyor dishwasher 2. The purpose of this read/write unit 61 is, in particular, to transfer data and/or commands preferably wirelessly between the at least one temperature sensor 60 and at least one evaluation device 62. In particular, the at least one read/write unit 61 is designed to read out, preferably automatically after the end of the recording of n whole-number temperature profiles, these temperature profiles and/or the data corresponding to the temperature profiles from the temperature sensor 60, where n 1.

[0104] The evaluation device 62 of the monitoring system is designed not only to receive the data of the temperature profile with respect to time recorded by the at least one temperature sensor 60, but also to evaluate them. For this purpose, the evaluation device 62 is designed (e.g., programmed or otherwise configured) in particular to ascertain a value of a notional unit of quantity of heat from the temperature profile recorded by the temperature sensor 60.

[0105] For example, for this purpose the evaluation device 62 is designed to extract a temperature value from the temperature profile recorded by the at least one temperature sensor 60 at pre-defined or pre-definable times (measurement points), and from the extracted temperature value to determine an equivalent value of a quantity of heat according to a pre-defined or pre-definable mapping. An example of such a mapping is shown in FIG. 1.

[0106] In accordance with advantageous implementations, the corresponding temperature value is extracted from the recorded temperature profile once per second and in accordance with the mapping, for example the mapping shown in FIG. 1, converted into an equivalent value of a quantity of heat.

[0107] The evaluation device 62 of the monitoring system is also designed to determine the value of the notional heat quantity unit by forming a sum of the equivalent values of the quantity of heat from measurement points of the temperature profile. In this context, it is conceivable that the determined value of the notional heat quantity unit is compared with a predetermined setpoint value, such as—expressed in terms of the requirements in accordance with NSF—the 3,600 HUE values. At the same time, a warning and/or notification to this effect should be output by the evaluation device 62 if the measured value of the notional heat quantity unit falls below the setpoint value.

[0108] The read/write unit 61 is preferably provided with an interface to send the data read out from the temperature sensor 60 to the evaluation device 62 or the control device 50 of the dishwasher 2.

[0109] As is schematically indicated in FIG. 3, viewed in the conveying direction of the washware in front of the first treatment zone of the dishwasher 2 an inlet region 11 is provided, in which a further read/write unit 63 or similar unit, such as an inductively operated unit of the monitoring system, is arranged. This read/write unit 63 can be used to initiate the temperature sensor 60, as soon as it moves past the region of influence of the read/write unit 63 via the conveyor device 4.

[0110] The control device 50 of the dishwasher 2 according to the invention is also preferably designed (e.g., programmed or otherwise configured) so as to adjust the temperature in the at least one wash zone 10, 12, 14, and/or at least one final rinse zone 16, 18, or the temperature of the liquid to be sprayed in the at least one washing zone 10, 12, 14 and/or the at least one final rinse zone 16, 18, and/or the speed at which the washware is conveyed through the treatment zones 10, 12, 14, 16, 18, 40 of the dishwasher 2.

[0111] In this context it is conceivable if the control device 50 preferably automatically adjusts the temperature or the action time/conveying speed, in order to ensure at all times that the hygiene-relevant temperatures in accordance with the current standard or directive are complied with.

[0112] It is also conceivable that the control device of the dishwasher 2 informs the operator of the dishwasher 2 accordingly, preferably via data transmission (app/cloud).

[0113] In the following the underlying concept of the invention is summarized once again as follows:

[0114] During normal operation a temperature sensor 60, fixed for example to the conveyor belt of the conveyor device 4, passes through the wash and final rinse zones of the conveyor dishwasher 2. During the traverse, the temperature is recorded as a function of time. The recording starts when the sensor enters the cleaning tunnel and is stopped on its exit. At the same time, the recorded temperature profile is transferred to the evaluation device 62, which can be part of the control device 50 of the dishwasher 2 (e.g. via RFID, Bluetooth, WiFi, NFC, radio, etc.), and is converted into the HUE-value obtained in accordance with the NSF/ANSI3 specifications. This may be displayed and documented directly on the evaluation device 62 and/or control device 50 (operating log) or forwarded to a management system.

[0115] The monitoring system integrated in the dishwasher 2 consists of at least one temperature sensor 60 and at least one read/write unit 61, 63 as well as at least one evaluation device 62. The temperature sensor 60 can be mounted on or integrated in the conveyor belt, the dish rack, a piece of dishware (plate, small bowl, glassware, cutlery, cookware, etc.) or a specific measurement body. The sensor itself is provided with a data store which can record the temperature profile as a function of time.

[0116] The recording is started as soon as the temperature sensor 60 enters or is inserted into the cleaning tunnel of the machine 2. In so doing, the “Start” command can be triggered by the write/read unit 63 itself or an additional sensor (e.g. inductive sensor).

[0117] At the end of the tunnel, the recorded temperature profile is transferred as a data block by a second read/write unit 61 to the machine controller 50 or the evaluation device 62 (e.g. via RFID, Bluetooth, WiFi, NFC, radio, etc.).

[0118] The machine controller 50 or the evaluation device 62 calculates the HUE-value obtained in accordance with NSF/ANSI3 from the temperature profile, and depending on the result, can output information to operators or to the management system. For example, the HUE-value could be directly displayed and evaluated on a display unit of the machine controller 50 or the evaluation device 62 (green for >3,600 HUE and red for <3,600 HUE). Also, it is conceivable to change the operating state of the machine 2 depending on the HUE value (for example hygiene stop), or to change the operating parameters (e.g. tank temperature, conveyor speed, throughput, etc.). For documentation of the hygiene performance the HUE values can either be stored directly in the operating log of the machine stored or transferred to an external database.

[0119] Based on this concept, the following variations would be possible:

[0120] The starting and the reading of the measurement series could also be implemented by only one read/write unit 63.

[0121] An immediate, continuous data transfer from the temperature sensor 60 to the machine controller 50 or the evaluation device 62 (e.g. via radio) would also be conceivable.

[0122] If a temperature sensor 60 mounted on the washware (for example, dishes) or on a specific test specimen is used, readout using an external or separate readout/evaluation unit is also conceivable. This could be located in a control cabinet of the dishwasher 2 or in an additional hand-held device. In this case the starting and the reading of the measurement would also be possible using a smartphone app (via WiFi, Bluetooth, NFC, etc.).

[0123] If the system is used in stationary machines (cover-type and under-counter machines) the measurement would be started by a read/write unit at the beginning of the wash cycle and evaluated after the completion of the rinse cycle. Of course, the implementation via a smartphone app (via WiFi, Bluetooth, NFC, etc.) would also be feasible here.

[0124] By means of the method described above the hygiene parameters temperature (HUE-value) prescribed within the NSF/ANSI3 can be implemented and documented costeffectively and automatically.

[0125] The invention is not limited to the embodiments shown in the drawings, rather it results from a combination of all the features disclosed herein.