Method for assessing and guaranteeing the thermal hygiene effect in a multi-tank dishwasher

Abstract

Method for assessing and guaranteeing the thermal hygiene effect in a multi-tank dishwasher in which at least one sensor (40; 50, 51, 52, 53) is arranged which transmits the temperature inside at least one treatment zone (4, 14, 18, 25) to a machine control system (36), in particular to the control system of the multi-tank dishwasher, said method comprising the following method steps: a) detecting the temperature inside at least one of the treatment zones (4, 14, 18, 25) by means of the sensor (40, 50, 51, 53), b) determining the heat applied to the items to be cleaned in at least one of the treatment zones (4, 14, 18, 25), on the basis of the temperature determined under (a), c) subsequently comparing the heat input in the at least one treatment zone (4, 14, 18, 25) with a predefined heat input, and d) varying the transportation speed of the items to be washed through the multi-tank dishwasher as a function of the result of the comparison of the heat input values carried out according to method step (c), or varying the temperature J in at least one of the method parameters acting on the heat input values as a control variable in a control loop for at least one of the treatment zones (4, 14, 18, 25).

Description

[0001] The invention relates to a method for assessing and ensuring the thermal hygiene effect on items being washed in a dishwasher during the cleaning process. Technical area

[0002] In commercial settings, multi-tank dishwashers are used alongside single-chamber dishwashers for cleaning items. In multi-tank dishwashers, the items to be cleaned are transported through the various zones of the dishwasher by a conveyor system. These machines typically include at least one wash zone, at least one rinse zone, and optionally a drying zone. Multi-tank dishwashers, in which the items pass through different treatment zones, are generally designed as either belt conveyor or rack conveyor machines. Both designs share the common feature that the items are continuously transported through the individual treatment zones by the conveyor system. These treatment zones are usually designed as chambers with openings in the direction of travel of the conveyor system, through which the items are transported. State of the art

[0003] At the start of operation of a multi-tank dishwasher, the wash water reservoir for the wash zone is filled with fresh water and heated to the preset wash tank temperature. Detergent is then added to the wash water. This process is analogous if several wash zones are arranged in series. The wash zone typically has a wash water circulation pump that draws wash water from the reservoir and sprays it onto the items being washed via a spray system assigned to that zone, in order to remove the dirt adhering to the items. The wash water, along with the rinsed dirt, then flows back into the reservoir.

[0004] A sieve system filters the rinsed dirt out of the rinse water.

[0005] In the rinse cycle, loose detergent and dirt residues on the dishes are rinsed off with hot fresh water sprayed by a dedicated spray system. In some multi-compartment dishwasher models, the rinse water from the first use is collected in a pumped rinse tank and sprayed again onto the dishes using a pump and another spray system. This step takes place before the final rinse with fresh water. Some of the fresh water, or rinse water, is then added to the wash water reservoir to dilute the dirt particles present there. The dishes are then transported to the optional drying zone, where they are dried.

[0006] The cleaning result is significantly influenced by the process factors: cleaning agent concentration, contact time of the item being cleaned from initial contact with the rinse water in the first rinse zone until it leaves the final rinse zone, the mechanics of the spray systems or spray jets in the rinse zones, and the temperatures in the individual rinse zones. Methods for measuring the process parameters cleaning agent concentration, contact time of the item being cleaned with the rinse water in the first rinse zone until it leaves the final rinse zone, and the mechanics in the rinse zone are known. For example, the cleaning agent concentration is typically measured via the conductivity of the rinse liquid. The contact time is determined by the transport speed of the conveying system, and the washing mechanics are determined by the pressure of the circulation pump and the design of the nozzles of the spray system in the respective rinse zone.The temperature of the rinse water in each treatment zone is measured by temperature sensors. Because the rinse water cools down after leaving the spray nozzles of the spray system, the temperature reached on the surface of the item being cleaned is not identical to the rinse water temperature. However, for germ reduction on the surface of the item being cleaned, this temperature, as well as the duration for which these temperatures act on the item, is crucial. The duration of exposure to a specific temperature on the surface of the item being cleaned is referred to as the heat equivalent.

[0007] The relationship between temperature and time and germ reduction is, among other things, the basis of regulations and standards designed to ensure cleaning effectiveness in dishwashers. Based on tests conducted on multi-tank dishwashers, aimed at defining the process parameters necessary for reliable sanitization of the items being washed, DIN 10510 C.3 was adopted for Germany. This standard provides recommendations regarding temperature, detergent concentration, and the duration between the initial contact of the items with the wash liquid in the first wash zone and their exit from the final rinse zone. These parameters are then to be used in the individual process zones of the multi-chamber dishwasher to achieve the required germ reduction during operation at the customer's site. This standard is based on the germ reduction of precisely soiled test specimens after the cleaning process, as measured by contact plate tests.The test organism used in this test is E. faecium ATCC 6057.

[0008] The hygiene safety of multi-tank dishwashers at the end customer's site is verified through contact plate testing and the determination of the bacterial count in the wash water of the last wash tank. However, a disadvantage is that testing the bacterial reduction on-site at the customer's premises according to this standard is extremely complex and costly. Another drawback of this standard is that the same bacterial reduction could be achieved, for example, with a shorter contact time but higher temperatures in the individual treatment zones. This standard, however, does not permit such a scenario.

[0009] In the USA, the relationship between temperature and time and germ reduction is described by the NSF3 standard procedure. This standard is based on the reduction of tuberculosis bacteria, determined through experiments, through exposure to a specific temperature over time. The duration of this temperature effect is referred to as the "heat equivalent." The number of heat equivalents per second achieved at each temperature is specified in a table within this procedure. Using this table, a minimum temperature for the wash water in the main wash and rinse zones of a dishwasher is defined, which the dishwasher must reach to achieve the germ reduction required by this standard.For dishwasher manufacturers, this means that these temperatures must be factory-preset in the control system of the respective dishwasher and that these temperatures must actually be maintained during operation of the multi-tank dishwasher at the customer's site. In the process testing of a dishwasher using this method, a temperature sensor is attached to a plate. The plate is then placed in a predetermined position in the transport system of the multi-tank dishwasher and transported through the individual processing zones. The temperatures during the cleaning process are recorded. Based on the temperature profile during the transport of the items through the multi-tank dishwasher, the heat equivalents acting on the plate over the entire cleaning process are determined using the table mentioned above.This test must be performed for three different plate positions in a dish rack or on a conveyor belt. To meet the required germ reduction, at least 3600 heat equivalents must be achieved in each plate position, according to this regulation. An advantage of this method is that it can be carried out on-site at the customer's premises with relatively little effort to verify the proper functioning of the multi-tank dishwasher with regard to thermal sanitization. Another advantage is that the result is available immediately after the measurement, allowing for an immediate assessment of the cleaning process quality.

[0010] However, a disadvantage of operating the dishwasher is that the heat equivalents acting on the dishes during the washing process must be inferred from the temperatures of the wash water in the individual treatment zones, and not the actual heat equivalents applied to the items being washed.

[0011] In the field of cleaning and disinfection equipment, prEN ISO 15883-1 describes a method for assessing hygiene efficacy that also uses the relationship between microbial reduction and temperature over time. This relationship is referred to as the A0 value and is also presented in tabular form or calculated using a mathematical formula. The A0 value is described in more detail in Annex A of this standard and is defined as the time equivalent in seconds at 80°C at which a given disinfection effect is achieved. It corresponds analogously to the heat equivalents of the NSF3 standard, but based on a different test organism. The test organism used in this method is Enterococcus faetium. Here, too, a minimum A0 value to be achieved at every point in the cleaning / disinfection equipment's rinsing chamber is specified.However, this method is not yet used to assess commercial dishwashers in Europe.

[0012] The methods and standards described above for ensuring the cleaning result with regard to thermal sanitization in a multi-tank dishwasher all have the disadvantage that the process parameters are fixed during operation. This applies particularly to the temperatures in the wash and rinse zones. If several programs or transport speeds are selectable, the multi-tank dishwasher must be designed for the worst-case scenario. This generally means for the fastest transport speed.Because there is no known method for measuring the actual heat equivalents acting on the items being washed, which is integrated into the multi-chamber dishwasher's control system and regulates the washing process, the disadvantage arises that the multi-tank dishwasher cannot be optimally adapted to the actual washing process or program with regard to the heat equivalents. A further disadvantage of the current state of the art is that the actual heat equivalents transferred to the items being washed are not measured; instead, it is assumed that the required germ reduction is achieved based on the process parameters specified by the standard or procedure.

[0013] WO 97 / 29789 A1 discloses a monitoring procedure for sterilization processes.

[0014] EP 1 196 650 B1 relates to a method for monitoring a washing process. An independent, wireless monitoring device is attached to and moved along the conveyor belt of an industrial dishwasher. The measured data is recorded in a monitoring unit. This device allows the temperatures at the individual washing zones to be recorded and evaluated at a later time. Based on the measured temperature values, the heat equivalents transferred to the items being cleaned could then be determined. The difference to temperature recording according to the NSF3 standard method is that the temperature measurement is wireless.However, the device known from EP 1 196 650 B1, similar to the test method according to the NSF3 standard, serves only to control the process temperatures with regard to the measured process temperature, is not evaluated by the control system of the dishwasher and therefore does not serve to directly control the process parameters of the multi-tank dishwasher.

[0015] DE 196 08 036 C5 indicates that the dependence of the rinse water quantity on the transport speed of the conveying system of the multi-tank dishwasher is directly related. DE 196 08 036 C5 does not address in detail the dependence of the clear rinse water quantity on the heat equivalents actually transferred to the items being washed. Description of the invention

[0016] The object of the present invention is to provide a method for detecting the heat equivalents transferred to the material to be cleaned in order to eliminate the disadvantages of the prior art solutions described above and at the same time increase the process reliability with regard to the thermal hygiene effect.

[0017] According to the invention, this problem is solved by the features of claim 1.

[0018] Following the solution proposed according to the invention, a method for assessing and ensuring the thermal hygiene effect in a multi-tank dishwasher is proposed, in which at least one sensor is arranged that transmits the temperature within at least one treatment zone to a machine control, in particular the control of the multi-tank dishwasher. The following method steps are carried out: a) The sensor measures the temperature within at least one of the treatment zones, b) the heat input to the items to be cleaned in at least one of the treatment zones is then determined based on the temperature determined according to process step a), c) the heat input in the at least one treatment zone is then compared with a predetermined heat input, and d) depending on the result of the comparison of heat inputs carried out according to process step c), the transport speed of the items through the multi-tank dishwasher or a temperature ϑ of at least one process parameter affecting the heat inputs is varied as a manipulated variable in a control loop for at least one of the treatment zones. where, in the temperature measurement by at least one stationary sensor, a prediction of the heat input is made based on an extrapolation of the temperature values ​​of a subsequent treatment zone seen in the transport direction of the washed goods.

[0019] Within process step c), following the method proposed according to the invention, it is determined whether the heat input into at least one of the treatment zones corresponds to the specified heat input, exceeds the specified heat input or falls below the specified heat input.

[0020] Depending on the result of this comparison and, if applicable, other parameters relevant to the washing result, if the specified heat input is exceeded, the transport speed of the items being washed, which serves as a control variable for the control loop, is increased so that the items being washed are transported through the relevant treatment zone of the multi-tank dishwasher more quickly. Alternatively, instead of increasing the transport speed through the relevant treatment zone of the multi-tank dishwasher, if the specified heat input is exceeded, the temperature can be lowered in at least one heated zone of the treatment zones, or the temperature in a subsequent treatment zone can be lowered to compensate for the increased heat input in the preceding treatment zone.In addition, the temperature in a treatment zone already passed through by the items being washed can be lowered, which allows for energy savings in terms of heating at least one treatment zone and enables a predictive operating style of the multi-tank dishwasher, which is highly energy efficient.

[0021] If, however, it is determined that the specified heat input is not met by the actual heat input in at least one of the treatment zones, the transport speed of the items being washed through that zone can be reduced via the machine control system. Alternatively, if the aforementioned criterion is met—i.e., the actual heat input falls below the specified level—the system can also stop the flow of the items through the treatment zone of the multi-tank dishwasher and / or display this condition on the machine's screen, so that the operator is alerted and can take appropriate action.It is also possible, even if the heat input falls below the specified level in at least one of the treatment zones of the multi-tank dishwasher, to simply register this condition and take no action, but instead to ensure continuous monitoring of the heat input in the respective heated treatment zones of the multi-tank dishwasher. Continuous monitoring of the heat input in the heated treatment zones can also be carried out if it is determined that the specified heat input has been exceeded by the actual heat input.

[0022] The temperature in each treatment zone of the multi-tank dishwasher is measured by stationary sensors assigned to each zone and transmitted to the machine control system, which calculates the actual heat input in the treatment zones. Crucially, the stationary sensor transmits the temperatures measured individually in at least one treatment zone to the machine control system. The machine control system then calculates the actual heat input in one or more of the treatment zones already traversed or yet to be traversed, taking into account the transport distance of the items being washed in each zone and the transport speed.

[0023] In the machine control system, the actual heat input in the relevant treatment zone can be determined based on the temperature values ​​recorded by the stationary sensor, also depending on the residence time of the items being washed in the respective treatment zone.

[0024] In the machine control system of the multi-tank dishwasher, the predefined heat inputs into the overall system are stored to ensure hygienic effectiveness. This is achieved, for example, either by using heat equivalents (HUE) according to the NSF3 standard, or by using the A0 values ​​from EN 15883-1 Annex 1, or by any defined relationship between the temperature (ϑ) and corresponding heat equivalents. The actual heat input acting on the items in at least one of the treatment zones of the multi-tank dishwasher is then compared to this data stored in the machine control system and the resulting predefined heat inputs.

[0025] In a further embodiment of the method proposed according to the invention for assessing and ensuring the thermal hygiene effect in a multi-tank dishwasher, if the actual heat input falls below the predetermined level, the transport speed of the items being washed through one of the treatment zones can be temporarily set to 0, i.e., the transport of the items through the multi-tank dishwasher can be stopped. This results in a longer dwell time of the items in at least one of the treatment zones of the multi-tank dishwasher, thus increasing the actual heat input.

[0026] In practical implementation of the method proposed according to the invention, depending on the result of the comparison between the actual heat input and the respective predetermined heat input in at least one, preferably several, of the treatment zones of the multi-tank dishwasher, the volumetric flow rate of a fresh water stream supplied to, for example, a fresh water clear rinse zone can be varied, i.e., increased or decreased, or the temperature of the quantity of water supplied to the fresh water clear rinse zone can be varied in order to influence the actual heat input. Similarly, in practical implementation of the method proposed according to the invention, the volumetric flow rate circulated within a pump clear rinse zone of a multi-tank dishwasher can also be increased or decreased.In at least one of the wash zones upstream of the fresh water rinse zone or the pump rinse zone of the multi-tank dishwasher, the heating elements installed, for example, in the tanks associated with the wash zones, can have their heating output varied depending on the result of the comparison between the actual heat input and the specified heat input. In the drying zone of the multi-tank dishwasher, which is usually downstream of the fresh water rinse zone or the pump rinse zone, the temperature of the drying air blown onto the items being washed can be varied, i.e., its temperature can be increased or decreased, in order to vary, i.e., increase or decrease, the actual heat input.Furthermore, according to the method proposed in the invention, additional heat input into at least one of the treatment zones of the multi-tank dishwasher is possible by means of an infrared emitter, which is preferably arranged in or behind a drying zone in the direction of transport of the items being washed. This provides another way to influence the heat input into the overall multi-tank dishwasher system, even after the treatment zones upstream of the drying zone, which have already been traversed by the items being washed, have been passed through. As an alternative to the additional heat input via an infrared emitter, electromagnetic radiation, or microwave, shortwave, or longwave irradiation of the items being washed can be applied.

[0027] Based on the temperature data available in the machine control system of the multi-tank dishwasher, which is transmitted to it via the sensor permanently assigned to at least one treatment zone, the temperature can be adjusted in a treatment zone already passed through by the items being washed. Furthermore, a prediction of the heat input can be made based on an extrapolation of the temperature values ​​of a subsequent treatment zone in the direction of transport. If the temperature is measured in at least one of the treatment zones using a sensor permanently assigned to it, the temperature can be determined in that at least one treatment zone, or a temperature gradient present in a heated treatment zone can be modified.

[0028] Advantageously, the temperature can be adjusted in a treatment zone already passed by the goods being washed, and a prediction of the heat input can be made based on an extrapolation of the temperature values ​​in the transport direction of the goods being washed in subsequent treatment zones.

[0029] The method proposed according to the invention advantageously enables a multi-tank dishwasher to actively monitor the hygiene of the items being cleaned and, for example, to initiate suitable measures in the event of irregularities during the washing process, such as the introduction of items with different heat capacities and the associated change in energy consumption, or the introduction of cold water by the machine control system. These measures could include, for example, the aforementioned reduction or increase in the transport speed of a conveying device. Furthermore, the method proposed according to the invention allows for the straightforward demonstration of proper functioning of the multi-tank dishwasher with regard to its thermal hygiene effect during operation at the end user's site, without, for example, actively introducing bacterial strains specified in the aforementioned standards into the multi-tank dishwasher.

[0030] The method proposed according to the invention also allows for ensuring the hygienic effect during the operation of the multi-tank dishwasher at the operator's premises. drawing

[0031] The invention is described in more detail below with reference to the drawing.

[0032] It shows: Figure 1 shows a section of a continuous washing machine with a rinsing zone, a pump rinsing zone and a fresh water rinsing zone and wireless sensors not according to the invention, Figure 2 shows a section of a continuous washing machine with sensors assigned to each of the individual treatment zones, which are permanently installed according to the invention. Examples of implementation

[0033] According to the representation Figure 1A continuous dishwasher 1 is to be removed, in which the goods 32 to be cleaned are transported in the transport direction 2 through various treatment zones of the continuous dishwasher 1 and which does not serve to carry out a method according to the invention. A conveying device 3, which in the illustration according to Figure 1 Designed as an endless conveyor belt, it transports the item 32 to be cleaned through the various treatment zones of the continuous dishwasher 1. Viewed in the transport direction 2 of the item 32 to be cleaned, it first passes a rinsing zone 4.

[0034] Within rinsing zone 4, there is a first rinsing system 5 and a second rinsing system 6. Cleaning fluid 7 emerges from this system in a jet stream. The first rinsing system 5 and the second rinsing system 6 are supplied with cleaning fluid via a first pump 8. The first pump 8 is located within a rinsing zone tank 9, which is assigned to rinsing zone 4. A pump housing 10 is located in the upper part of the first pump 8; the rinsing zone tank 9 is covered by a tank cover screen 11. The rinsing zone tank 9, assigned to rinsing zone 4, contains a heated or unheated water supply.

[0035] Rinsing zone 4 is separated from the pump rinsing zone 14, which adjoins it (viewed in the transport direction 2 of the goods 32 to be cleaned), by means of a partition curtain 13. The rinsing zone tank 9 is separated from the tank located below the pump rinsing zone 14 or the fresh water rinsing zone 18 by a partition wall 12.

[0036] In the representation according to Figure 1 In a diagram that does not depict an embodiment of the invention, the material 32 to be cleaned, exiting the rinsing zone 4, enters a pump rinsing zone 14 after passing through the separating curtain 13. The pump rinsing zone 14 is supplied by a second pump 15. The cleaning fluid 7, exiting the pump rinsing zone 14 from a first spray tube 16 and a second spray tube 17, wets the material 32 to be cleaned from both the top and bottom. The spray tubes 16 and 17 arranged in the pump rinsing zone 14 are mounted on a curved tube, resulting in an offset of the first spray tube 16 relative to the second spray tube 17 in the pump rinsing zone 14.

[0037] The same applies to a fresh water rinsing zone 18, which can be located downstream of the pump rinsing zone 14. The fresh water rinsing zone 18 comprises an upper spray pipe 20 and a lower spray pipe 21. The two spray pipes 20 and 21 are also arranged offset from each other according to the spray pipe path 19 – viewed in the transport direction 2 of the material to be cleaned. The volume of fresh water exiting the upper spray pipe 20 and the lower spray pipe 21 wets the material to be cleaned 32 from both its top and bottom surfaces.

[0038] A heat recovery unit 23 is connected downstream of the fresh water rinsing zone 18. This unit contains an exhaust air fan 24, which extracts exhaust air from the continuous dishwasher 1. A drying zone 25 is connected to the heat recovery unit 23 in the transport direction 2 of the item 32 to be cleaned. The drying zone 25 includes a fan 26, to which a sensor 27 is assigned.

[0039] The air exiting the blower 26 is blown onto the top of the item to be cleaned via outlet nozzles 28. In the illustration according to Figure 1 The blower 26 is equipped with two outlet nozzles 28, which – viewed in the transport direction 2 of the item 32 to be cleaned – are arranged one behind the other. The drying zone 25 is shielded from an outlet section 30 of the continuous dishwasher 1 by a further separating curtain 33. In the area of ​​the outlet section 30 of the continuous dishwasher 1, as shown in the illustration in Figure 1The dried and partially cooled, now cleaned material 32 can be removed from the conveyor device 3, which is designed as a conveyor belt. The conveyor device 3, designed as a conveyor belt, is driven by a drive 31, which can be located at the end of the discharge section 30. (See illustration.) Figure 1Furthermore, it can be seen from the figure, which does not show an embodiment according to the invention, that non-inventive wireless sensors 40 can be attached to individual holding devices 33 of the conveying device 3. The mounting position of the wireless sensor 40 in the upper area of ​​holding devices 33 for the material 32 to be cleaned ensures that the temperature value detected by the sensor 40, which is transmitted via a signal 35 to a receiver 34 of the control unit 36, corresponds to the temperature of the material 32 to be cleaned that is held in the conveying device 3. Alternatively, the wireless sensor 40 can also be mounted on a transport element of the circulating conveying device 3, which is preferably designed as a conveyor belt, to detect and transmit the temperature signal 35. According to the figure in Figure 1In the illustrated non-inventive embodiment, the wireless sensor 40 is transported by the conveying device 3 together with the item 32 to be cleaned through the individual treatment zones 4, 14, 18, and 25 of the continuous dishwasher 1. The temperatures recorded can be transmitted to the control unit 36 ​​either continuously at the end of each individual treatment zone 4, 14, 18, 25 or at the end of the entire process section. The control unit calculates the heat equivalents transferred to the item 32 to be cleaned during the washing process and, if necessary, corrects, for example, the transport speed of the conveying device 3 in the transport direction 2, the temperature of the rinse water applied to the item 32 in the pump rinse zone 14 or in the fresh water rinse zone 18, or other process parameters.

[0040] Figure 2Figure 1 illustrates an embodiment according to the invention: a continuous dishwasher with fixed sensors assigned to each of the individual treatment zones.

[0041] By means of the method proposed according to the invention and the correspondingly designed continuous dishwasher 1, it is possible to always achieve an optimal transport speed of the conveying device 3 in the individual treatment zones 4, 14, 18, 25 of the continuous transport of the goods to be cleaned 32 through the continuous dishwasher 1, depending on the process steps taking place there.

[0042] In the various treatment zones 4, 14, 18, 25 of the continuous dishwasher 1, sensors 50, 51, 52, 53 are preferably installed in fixed positions. The respective installation positions of the sensors 50, 51, 52, 53 are shown as examples; depending on the other conditions, the positions of the respective sensors 50, 51, 52, 53 are selected such that the temperatures measured by them correspond to the temperatures of the goods 32 to be cleaned as they pass through the various treatment zones 4, 14, 18, 25 within the continuous dishwasher 1. The sensors 50, 51, 52, and 53 exchange measurement data with the control unit 36 ​​of the continuous dishwasher 1. The control unit 36, which is assigned to the continuous dishwasher 1, can either be an internal control unit, i.e. located inside the continuous dishwasher 1, or an external control unit, i.e. located outside the dishwasher 1.The control unit 36 ​​is located outside the continuous dishwasher 1. The control unit 36 ​​comprises a microprocessor (CPU) 45 and a data storage unit 46. All functions relating to the program steps running in the continuous dishwasher 1, including the procedure for assessing the hygienic effect running within the continuous dishwasher 1, are controlled via a main control line. The control unit 36 ​​also includes a measurement data acquisition unit 47, which records the temperature values ​​detected by the at least one stationary sensor 50, 51, 52, 53 and stores them in a data storage unit 46. The stationary sensors 50, 51, 52 and 53 are connected via the [unclear - possibly referring to a specific control unit or component]. Figure 2 The depicted line is connected to the control unit 36, via which the individual process steps of the continuous dishwasher 1 are controlled.

[0043] Furthermore, the control unit 36 ​​regulates the electrical power supply of pumps 8 and 15 via a power regulator, which can be installed upstream of each pump. A power regulator can also be installed upstream of the fresh water pump, i.e., the second pump 15, to control its electrical power supply. The same applies to a power regulator that controls the power supply of a heating element for the rinse water, as well as to another power regulator that controls the power supply of a heating element in a potentially installed instantaneous water heater or boiler for heating the rinse water.

[0044] The controller 36 stores the values ​​for the heat equivalents within its data memory 46. These values ​​are relevant for determining or classifying the hygienic performance of a continuous dishwasher 1, either according to the NSF3 standard or the A0 value method. For example, the data memory 46 of the controller 36 can store the following A0 values, according to prEN ISO 15883, which is expected to be used in Europe:

[0045] The A0 value, which can be obtained from the table above, is defined as the time equivalent in seconds during which a disinfection effect is achieved. The A0 value of a moist heat disinfection process indicates the killing of germs, specified as the time equivalent in seconds at a temperature transferred to the product, such as the item to be cleaned (item 32), by the process.

[0046] A permanently installed sensor 50, 51, 52, 53, which is used in a respective treatment zone 4, 14, 18, 25 of a continuous dishwasher 1, can be adjusted to the temperature sensor used within the NSF3 standard test procedure or the A 0 test procedure in such a way that the same heat equivalents can be determined via the control 36 within the continuous dishwasher 1 as in the NSF3 standard procedure or in the A 0 test procedure. The heat equivalents achieved within a program step are determined via the sensors 50, 51, 52, 53 installed according to the invention within the respective treatment zone 4, 14, 18, 25 or the sensors 40 installed on the transiting transport device according to the invention and the control 36 and compared with the table values ​​stored in the data memory 46, for example in the case of prEN ISO 15883-1, the values ​​stored there.If the values ​​for the heat equivalents reached within the respective treatment zones 4, 14, 18, 25 of the continuous dishwasher 1, determined via the sensors 50, 51, 52, 53 installed according to the invention within the respective treatment zones 4, 14, 18, 25 or via sensors 40 not installed according to the invention on the transport device, are too low, the temperature of the rinse solution held in the rinse solution tank can be increased via the control unit 36, or the temperature of the fresh water supplied within the rinse zone 18 via the rinse systems 20, 21 arranged there can be increased via the control unit 36. For this purpose, the corresponding power controllers assigned to the respective pumps 8, 15 are controlled via the control unit 36.Furthermore, depending on the heat equivalent values ​​calculated by the control unit 36, the transport speed of the item 32 to be cleaned in transport direction 2 through the continuous dishwasher 1 can be varied. If the heat equivalent values ​​required according to the aforementioned standards are not reached, the drive of the conveyor 3 can, for example, be influenced by the control unit 36 ​​so that it runs more slowly, thus transporting the item 32 to be cleaned through the individual treatment zones of the continuous dishwasher 1 at a lower speed. This increases the exposure time of the heat equivalents, ultimately contributing to ensuring or increasing the temperature acting on the item 32 to be cleaned or the cleaned item 32.

[0047] If the heat equivalent values ​​specified according to the NSF3 standard or prEN ISO 15883-1 are reached in the respective treatment zones 4, 14, 18, 25 of the continuous dishwasher 1, the items 32 to be cleaned are transported to the next of these treatment zones 4, 14, 18, 25. The determined heat equivalent values ​​can be displayed on a display 48.

[0048] A further advantage of the method proposed according to the invention, implemented in a continuous dishwasher 1, for assessing and ensuring the hygienic effect is that the continuous dishwasher 1 actively monitors the hygiene of the items 32 being cleaned. Irregularities in the washing process, such as the introduction of a large quantity of cold water into, for example, the rinse water tank and a resulting drop in temperature within the wash zone 4, can be compensated for by suitable countermeasures initiated via the control unit 36. For example, the final rinse cycle can be extended via the control unit 36, or the temperature of the rinse water tank can be increased by appropriately controlling a power regulator assigned to the heating element of the tank to counteract the temperature drop caused by the introduction of cold water.Furthermore, as mentioned above, it is possible to vary the transport speed of the conveyor belt through the individual treatment zones 4, 14, 18, 25 of the continuous dishwasher 1 based on the heat equivalent values ​​determined in the control unit 36, which are based on the temperatures detected by the non-inventive wireless sensors 40 or by the inventive stationary sensors 50, 51, 52, 53. Using the method proposed according to the invention, it is possible to detect the respective heat equivalents achieved at each process step within the continuous dishwasher 1, regardless of irregularities, before the start of each process step, and to evaluate them according to the requirements of the NSF3 standard or the prEN ISO 15883-1 standard and to control the process parameters of the continuous dishwasher 1 accordingly.The calculated heat equivalent values ​​can be displayed on display 48. This allows the user of the continuous dishwasher 1 to monitor and control the thermal hygiene effect during each process step.

[0049] The method proposed according to the invention can preferably be applied to the one described in the Figure 2 implement the multi-tank dishwasher shown, designed as a continuous flow dishwasher, which has at least one cleaning zone, one pump rinse zone, one fresh water rinse zone and, if necessary, one drying zone.

[0050] The above in connection with the Figure 1 and 2The illustrated continuous dishwasher 1 has a machine control unit comprising at least one microprocessor 45, a data storage device 46, a measurement data acquisition device 47, and a display 48. The temperatures within the at least one treatment zone 4, 14, 18, 25 are transmitted to the machine control unit 36 ​​via the sensors 27, the non-inventive wireless sensors 40, or the inventive stationary sensors 50, 51, 52, and 53. Prior to this, the temperatures within at least one of the treatment zones 4, 14, 18, 25 are detected by the non-inventive wireless sensors 40 or the inventive stationary sensors 50, 51, and 53. The machine control unit 36 ​​then determines the heat input to the items to be cleaned 32 in at least one of the treatment zones 4, 14, 18, 25 based on the previously determined temperature.In the machine control 36, a comparison is then performed between the heat input occurring in at least one treatment zone 4, 14, 18, 25 and a predetermined heat input. Depending on the result of this comparison of heat inputs, either the transport speed of the items being washed 32 through the continuous dishwasher 1 can be varied, or the temperature ϑ of at least one of the process parameters affecting the heat inputs can be varied as a manipulated variable in a control loop for at least one of the treatment zones 4, 14, 18, 25.

[0051] Depending on the result of the comparison, whether the heat input into at least one of the treatment zones 4, 14, 18, 25 corresponds to the specified heat input, it will be determined whether the specified heat input was exceeded, undershot, or exactly met.

[0052] If the specified heat input is exceeded, the transport speed of the items being washed 32 can be increased, or the temperature can be reduced in the relevant treatment zone 4, 14, 18, 25. If this is a heated treatment zone 4, 14, 18, 25, then, for example, in the case of a cleaning zone, the heating power of a heating element installed in a tank can be reduced, or the temperature can be reduced in a subsequent treatment zone – viewed in the direction of transport of the items being washed 32 through treatment zones 4, 14, 18, 25. It is also possible to reduce the temperature in a treatment zone 4, 14, 18, 25 that has already been passed by the items being washed 32, in order to optimize the required heating power input of the overall continuous dishwasher system 1.

[0053] If the comparison performed in the machine control 36 reveals that the actual heat input applied to the items 32 is less than the specified amount, the transport speed of the items 32 through at least one of the treatment zones 4, 14, 18, 25 can be reduced via the machine control 36. To achieve this, the drive powering the conveyor 3 can be reduced in terms of its rotational speed. Furthermore, the transport of the items 32 through the treatment zones 4, 14, 18, 25 in the conveying direction 3 can also be stopped via the machine control 36 and resumed after a dwell time. Alternatively, instead of interrupting the flow of the items 32 through the treatment zone 4, 14, 18, 25 of the continuous dishwasher 1, this can also simply be displayed on the display 48 of the machine control 36.Even if the specified heat input is exceeded by the actual heat input to the items being washed 32 in at least one of the treatment zones 4, 14, 18, 25, this fact can only be displayed via the display 48, whereby the operator(s) of the continuous dishwasher 1 are free to intervene via the machine control 36 and initiate countermeasures.

[0054] While in the continuous dishwasher according to Figure 1 If, according to the invention, the sensor 40 is not transported with the items to be cleaned 32 in the conveying direction 3 through the continuous dishwasher 1, the sensor 27 assigned to the drying zone 25 is permanently installed. The same applies to the Figure 2 The illustrated embodiment of the continuous flow dishwasher 1, where the sensors 50, 51, 52 and 53 are stationary and assigned to the respective treatment zones according to the invention. The Figure 1By means of the moving sensor 40 (not according to the invention), the temperature values ​​ϑ 1...n in the respective treatment zones 4, 14, 18, 25 can be determined during the transport of the items to be washed 32 in the conveying direction 3 through the continuous dishwasher 1, and after transmission to the machine control 36, the actual heat input in the respective treatment zones 4, 14, 18, 25 can be calculated. In the case of the Figure 2In the illustrated embodiment with stationary sensors 50, 51, 52 and 53 according to the invention, the heat input in the treatment zones 4, 14, 18, 25 is calculated taking into account the transport distance of the item to be cleaned 32 in the respective treatment zone in the conveying direction 3 and the prevailing speed of the conveying device 3. The heat input into at least one of the treatment zones 4, 14, 18, 25 can also be dependent on the residence time of the item to be cleaned 32 in the respective treatment zone 4, 14, 18, 25, for example by setting the restart time after a stop in the transport of the item to be cleaned 32 in the conveying direction 2 by the continuous dishwasher 1.

[0055] In the machine control 36, the specified heat inputs are stored either based on the heat equivalents (HUE) of the NSF3 standard or the A 0 values ​​of EN 15883-1 Annex 1 or an arbitrarily defined relationship between the temperature ϑ and the corresponding heat equivalents.

[0056] As explained above, if the heat input falls below the specified level due to the actual heat input in at least one of the treatment zones, the transport speed of the material 32 to be cleaned in transport direction 2 through one of the treatment zones 4, 14, 18, or 25 can be temporarily set to 0. To practically vary the heat input, the flow rate of the fresh water supplied to the fresh water clear rinse zone 18 can be varied, or the temperature of the fresh water 22 supplied to the fresh water clear rinse zone 18 can be adjusted. Within the pump clear rinse zone 14, the circulating flow rate can also be increased or decreased to vary the temperature. Heating elements arranged in tanks 9 in one or more rinse zones 4 of the continuous dishwasher 1 can have their heating power varied to vary the actual heat input in the rinse zones 4.Within the drying zone 25, the temperature of the air used for drying the goods 32 to be cleaned can be changed depending on the comparison of the specified heat input with the actual heat input.

[0057] In a further advantageous embodiment of the method proposed according to the invention, the Figure 2 The illustrated continuous dishwasher 1 is equipped with an infrared emitter, an electromagnetic radiation emitter or a microwave system or a short- or long-wave emitting device arranged behind the drying zone 25 in order to provide a further possibility, after passing through all treatment zones 4, 14, 18 and 25, to treat the goods 32 to be cleaned, which have already passed through the aforementioned treatment zones, again with regard to the heat input acting on the goods 32.

[0058] If the sensor is a moving sensor 40 not according to the invention, it can, in conjunction with the machine control 36, adjust the temperature in a treatment zone 4, 14, 18, 25 already passed by the item to be cleaned 32 and / or predict the heat input based on an extrapolation of the temperature values ​​of a subsequent treatment zone 4, 14, 18, 25 in the transport direction of the item to be cleaned 32, which enables an energy-optimized operating mode of the continuous dishwasher 1.

[0059] In the case of temperature measurement by means of a sensor 40 moving through the treatment zones 4, 14, 18, 25 not according to the invention, a correction of the temperature in a transport zone or a correction of the temperature in at least one tank 9 assigned to a treatment zone can be carried out.

[0060] Are sensors 50, 51, 52, 53 as described in... Figure 2In contrast, if, according to the invention, the stationary sensors are fixedly assigned to the treatment zones 4, 14, 18, 25, then temperature measurement is carried out directly in the treatment zone, or a change in a temperature gradient present in one of the heated treatment zones 4, 14, 18, 25 can be achieved. With stationary sensors 40, 50, 51, 52, 53 according to the invention, the temperature can be adjusted in a treatment zone 4, 14, 18, 25 that has already been passed by the item to be cleaned 32, and a prediction of the heat input can be made based on an extrapolation of the temperature values ​​in the subsequent treatment zones 4, 14, 18, 25 in the transport direction 2 of the item to be cleaned 32. Reference symbol list 1 Continuous dishwasher 34 Recipient 2 Direction of transport of goods to be cleaned 35 Temperature signal, wireless 3 Funding institution 36 steering 4 Flushing zone 38 Basket 5 first flushing system 40 wireless sensor 6 second flushing system 7 Cleaning fluid 42 Run-out area 8 first pump 43 Procedure management 9 Flushing zone tank 10 Pump housing 45 Microprocessor (CPU) 11 Tank cover screen 46 Data storage 12 partition 47 Measurement data acquisition device 13 Partition curtain 48 Display 14 Pump rinse zone 15 second pump 50 Sensor flushing zone 16 first spray tube 51 Sensor pump rinse zone 17 second spray tube 52 Sensor for fresh water rinse zone 18 Freshwater rinsing zone 53 Sensor drying zone 19 Spray pipe route 20 upper spray tube 21 lower spray tube 22 Fresh water jet 23 Heat recovery system 24 Exhaust fan 25 Drying zone 26 fan 27 sensor 28 Outlet nozzle 29 outlet opening 30 Run-off area 31 drive 32 Item to be cleaned 33 Holding facilities

Claims

1. Method for assessing and guaranteeing the thermal hygiene efficiency in a multi-tank dishwasher in which there is at least one sensor (40; 50, 51, 52, 53) that transmits the temperature inside at least one treatment zone (4, 14, 18, 25) to a machine control system (36), in particular to the control system of the multi-tank dishwasher, said method comprising the following method steps: a) detecting the temperature inside at least one of the treatment zones (4, 14, 18, 25) by means of the sensor (40, 50, 51, 53), b) determining the heat input applied to the items to be cleaned in at least one of the treatment zones (4, 14, 18, 25), on the basis of the temperature determined under a), c) subsequently comparing the heat input in the at least one treatment zone (4, 14, 18, 25) with a predefined heat input, and d) as a function of the result of the comparison of the heat input values according to method step c), varying the transport speed of the items to be cleaned through the multi-tank dishwasher, or varying the temperature 9 of at least one process parameter acting on the heat input values as a control variable in a control loop for at least one of the treatment zones (4, 14, 18, 25), wherein, when the temperature is detected by at least one stationary sensor, a prognosis of the heat input is made on the basis of an extrapolation of the temperature values of a downstream treatment zone (4, 14, 18, 25) viewed in the transport direction of the items to be cleaned.

2. Method according to Claim 1, characterized in that, in method step c), it is determined whether the heat input in the at least one treatment zone (4, 14, 18, 25) corresponds to the predefined heat input, exceeds the predefined heat input or is below the predefined heat input.

3. Method according to Claim 2, characterized in that, if the predefined heat input is exceeded, the transport speed of the items to be cleaned is increased as control variable.

4. Method according to Claim 2, characterized in that, if the predefined heat input is exceeded, the temperature in at least one heated zone of the treatment zones (4, 14, 18, 25) is lowered.

5. Method according to Claim 4, characterized in that the temperature in a downstream treatment zone is lowered.

6. Method according to Claim 4, characterized in that the temperature is lowered in a treatment zone of said treatment zones (4, 14, 18, 25) through which the items to be cleaned have already passed.

7. Method according to Claim 2, characterized in that, if the heat input is below the predefined heat input, the transport speed of the items to be cleaned through at least one of the treatment zones (4, 14, 18, 25) is reduced.

8. Method according to Claim 2, characterized in that a discontinue criterion is satisfied, and the passage of the items to be cleaned through the treatment zones (4, 14, 18, 25) of the multi-tank dishwasher is stopped and / or this status is displayed.

9. Method according to Claim 1, characterized in that the temperature of the treatment zones (4, 14, 18, 25) is in each case detected by respective stationary sensors, and the heat input in the treatment zones (4, 14, 18, 25) is calculated as a function of the distance travelled by the items to be cleaned in the zone and as a function of the conveyor belt speed.

10. Method according to Claim 10, characterized in that the heat input in at least one of the treatment zones (4, 14, 18, 25) is calculated as a function of the dwell time of the items to be cleaned in the respective treatment zone (4, 14, 18, 25).

11. Method according to Claim 1, characterized in that the predefined heat input values correspond either to the heat equivalents (HUE) of the NSF3 standard or to the A0 values of EN 15883-1 Annex A, or any defined relationship between the temperature ϑ and the corresponding heat equivalents.

12. Method according to Claim 2, characterized in that, if the actual heat input is below the predefined heat input, the transport speed of the items to be washed through one of the treatment zones (4, 14, 18, 25) is temporarily set to 0.

13. Method according to Claim 1, characterized in that, as a function of the result of method step c), a fresh water flow delivered in a fresh-water final-rinse zone is varied in terms of its volumetric flow, or the temperature of the water added in the fresh-water final-rinse zone is varied.

14. Method according to Claim 1, characterized in that, as a function of the result according to method step c), the volumetric flow circulated inside a pump-operated final-rinse zone is increased or reduced.

15. Method according to Claim 1, characterized in that, as a function of the result of method step c), the heating power of the heating elements installed in a washing zone of the multi-tank dishwasher is varied.

16. Method according to Claim 1, characterized in that, as a function of the result of method step c), the temperature of the air located inside a drying zone of the treatment zones (4, 14, 18, 25) is varied.

17. Method according to Claim 1, characterized in that, as a function of the result of method step c), additional heat is input into the treatment zones (4, 14, 18, 25) by means of an infrared emitter which, viewed in the transport direction of the items to be cleaned, is preferably arranged downstream of a drying zone.

18. Method according to Claim 1, characterized in that, as a function of the result of method step c), additional heat is input into at least one treatment zone (4, 14, 18, 25) by electromagnetic radiation or by microwaves or by short or long waves.

19. Method according to Claim 1, characterized in that, when the temperature is detected by at least one stationary sensor assigned to a treatment zone (4, 14, 18, 25), the temperature in the at least one treatment zone (4, 14, 18, 25) is determined, or a temperature gradient present in a heated zone of the treatment zones (4, 14, 18, 25) is modified.

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