AUTOMATIC DOSING METHOD

Abstract

An automated dosing method for dosing a chemical in a tunnel dishwasher includes the steps of: detecting a rinse signal from a supplying solenoid valve for supplying a rinse water of the dishwasher; dosing a detergent amount apt to be inserted in a washing liquid, at a first load configuration of the dishwasher, for obtaining a washing mixture; and dosing a further detergent amount, apt to be inserted in the washing liquid for a restoration of the detergent in the washing mixture at an operating configuration of the dishwasher. The dosing step of a further detergent amount is performed periodically according to a predetermined time frequency.

Claims

1. An automated dosing method for dosing a chemical product in a tunnel dishwasher, comprising the steps of: detecting a rinse signal from a supplying solenoid valve for supplying a rinse water of the dishwasher; dosing a detergent amount apt to be inserted in a washing liquid, at a first load configuration of the dishwasher, for obtaining a washing mixture; dosing an additional detergent amount apt to be inserted in the washing liquid for a recovering of said detergent in said washing mixture at an operating configuration of the dishwasher, wherein said dosing step of an additional detergent amount is performed periodically according to a predetermined time frequency, equal to a recovery time interval t, said method also comprising a suspending step for suspending a contactor of said recovery time interval t at an interruption of said detecting step of the rinsing detection signal, and a reactivating step for reactivating said counter starting from a time t.sub.s at which said suspending step have been occurred, at a new detection of said rinsing signal.

2. The dosing method according to claim 1, further comprising a dosing step for dosing a rinse aid amount performed periodically.

3. The dosing method according to claim 1, wherein said dosing phase of a rinse aid amount has a flow rate, which is function of a volumetric flow rate of water used in a rinsing phase.

4. The dosing method according to claim 1, wherein said recovery time interval t is fixed or programmable by an operator.

5. The dosing method according to claim 1, wherein said dosing step of a detergent amount, at a first load configuration, has a time duration, which is function of a desired concentration value of the detergent in the washing mixture.

6. The dosing method according to claim 1, wherein said dosing step of an additional detergent amount has a time duration, which is function of a volumetric flow rate of the water used in a rinsing phase.

7. The dosing method according to claim 6, wherein said time duration is a function of said recovery time interval t.

8. A dosing system for dosing a chemical product comprising: a metering device; and a processing unit configured to perform an automated dosing method for dosing a chemical product in a tunnel dishwasher, comprising the steps of: detecting a rinse signal from a supplying solenoid valve for supplying a rinse water of the dishwasher; dosing a detergent amount apt to be inserted in a washing liquid, at a first load configuration of the dishwasher, for obtaining a washing mixture; dosing an additional detergent amount apt to be inserted in the washing liquid for a recovering of said detergent in said washing mixture at an operating configuration of the dishwasher, wherein said dosing step of an additional detergent amount is performed periodically according to a predetermined time frequency, equal to a recovery time interval t, said method also comprising a suspending step for suspending a contactor of said recovery time interval t at an interruption of said detecting step of the rinsing detection signal, and a reactivating step for reactivating said counter starting from a time t.sub.s at which said suspending step have been occurred, at a new detection of said rinsing signal.

9-10. (canceled)

11. A non-transitory computer readable medium having stored thereon computer executable instructions that, when executed by a processing unit, perform an automated dosing method for dosing a chemical product in a tunnel dishwasher, comprising the steps of: detecting a rinse signal from a supplying solenoid valve for supplying a rinse water of the dishwasher; dosing a detergent amount apt to be inserted in a washing liquid, at a first load configuration of the dishwasher, for obtaining a washing mixture; dosing an additional detergent amount apt to be inserted in the washing liquid for a recovering of said detergent in said washing mixture at an operating configuration of the dishwasher, wherein said dosing step of an additional detergent amount is performed periodically according to a predetermined time frequency, equal to a recovery time interval t, said method also comprising a suspending step for suspending a contactor of said recovery time interval t at an interruption of said detecting step of the rinsing detection signal, and a reactivating step for reactivating said counter starting from a time t.sub.s at which said suspending step have been occurred, at a new detection of said rinsing signal.

12. The dosing method according to claim 2, wherein the dosing step for dosing a rinse aid amount is performed periodically according to said predetermined time frequency.

Description

[0030] The present invention is now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to FIG. 1 of the attached drawing, which schematically shows the time course of some characteristic parameters of the object of the present invention.

[0031] The described method is particularly aimed to the dosing of detergent and/or rinse aid, in an industrial dishwasher of the tunnel kind.

[0032] As mentioned above, differently from the single tank washing machines, the tunnel machines have two separate environments, one for washing and the other for rinsing, environments sharing a same tank below.

[0033] In these machines, the racks, containing the crockery to be washed, pass through the entire dishwasher entering from one end of the machine and exiting from the opposite side, and the washing and rinsing phases take place simultaneously in different environments: while in one of the rooms the washing of a rack of dirty crockery is in progress, in another room the rinsing of another rack of crockery, already washed at an earlier time, takes place.

[0034] The method according to one embodiment of the present invention comprises a first step of a rinsing signal acquisition (RINSE signal), shown schematically in FIG. 1, corresponding to the actuation signal of the rinsing solenoid valve present in the dishwasher, i.e. of the solenoid valve which, when actuated, allows the passage of the rinsing water that is sprayed on the crockery to be rinsed.

[0035] The method is applicable regardless the specific kind of dishwasher, single or double solenoid valve.

[0036] In fact, in the so-called double solenoid valve dishwasher, a first solenoid valve dedicated to the loading of the water in the washing tank and a second solenoid valve dedicated to the rinsing operations are provided.

[0037] In the single solenoid valve dishwasher instead, the same valve is used for both the first loading and for rinsing. In this case the system detects the first loading condition based on the duration of activation of the sole available solenoid valve: a short-term activation (duration of less than a specific time threshold) is indicative of a rinsing phase, while an activation of long duration (higher than the specific threshold time duration) is indicative of a first loading phase. Typically, this time threshold is preset by the dosing system.

[0038] In both cases, the method according to the present invention provides an activation or a pause of a counter of the recovery phase as a function of the RINSE signal, in particular of the actuation signal of the rinsing solenoid valve.

[0039] As already mentioned, a first detergent dosing phase is carried out when a first loading condition is established, or when the empty washing tank of the dishwasher is filled with clean water, which in an industrial tunnel dishwasher generally occurs every two or three days or, in some cases, once a day.

[0040] The dosing phase of the first detergent loading comprises a step of inserting a determined detergent amount into the water previously inserted in the tank, defined in grams/litre by the manufacturer of the chemical product. In particular, it is necessary to not exceed this recommended amount of detergent to allow the dissolution of the detergent in the water and to not compromise the operation efficiency of the dishwasher.

[0041] The capacity of the washing tank is a defined parameter, which is preset by the operator.

[0042] Advantageously, using the above mentioned parameters, the method according to the invention obtains in an automatic way the detergent quantity required for the dosing operation as the product of the volumetric capacity of the tank (defined in litres) and the value of the detergent concentration (defined in grams/litre by the chemical product manufacturer).

[0043] Once the dosage relative to the first load have been done, the washing mixture in the tank, for example comprising the first loading water and the detergent dosed, it is in the ideal condition to perform the washing of the crockery.

[0044] During the washing step, the washing pump of the tunnel dishwasher machine takes the washing mixture from the washing tank, which is located in the lower part of the machine, and splash the pressurized mixture on the crockery in order to obtain the washing. In the tunnel dishwasher, although there are two distinct environments for washing and for rinsing the crockery, these sharing the underlying tank and therefore in the washing tank the clean and not soapy water used for rinsing is collected.

[0045] Obviously, the cleaning power of the mixture contained in the washing tank decreases during the operation of the machine because the rinsing water, not soapy, continuously falls into the washing tank and constantly dilutes its contents. As the washings are followed, it is therefore necessary to perform a detergent recovery phase, i.e. a dosing phase of a further amount of detergent to bring the washing mixture in the ideal detergent concentration conditions. Advantageously, the step of dosage of the additional amount of detergent of the further quantity of detergent (i.e. the recovery phase) is performed periodically according to a predetermined time frequency but adjusted by the RINSE signal, namely the activation of the rinsing solenoid valve.

[0046] As shown in the graph in FIG. 1, at the acquisition of the rinsing signal, a counter, which divides into a plurality of time intervals, of defined time duration t, the time duration of the rinsing signal, is activated, that as said in a tunnel dishwasher is a substantially continuous signal, during all the time in which the dishwashing machine is in operation.

[0047] Advantageously, the division of the rinsing duration in defined time intervals t allows to determine in an automatic the moment when it is necessary to dose the further detergent amount required for recovery the washing conditions, and also the relative amount to be dosed.

[0048] This amount is in fact obtainable from parameters defined and preset in the dosing system, in particular as the product of the volumetric flow rate of water used for rinsing (defined in litres/second), the recovery period t (defined in seconds) and the value of the detergent concentration to be obtained in the tank (defined in grams/litre by the manufacturer of the chemical product).

[0049] As schematically shown in FIG. 1, at each time interval t the method according to the present invention provides the dosing of a quantity of detergent in the washing water, calculated as described before:

Qt. DET=Flow Rate Rinsing Water*t*DET desired concentration.

[0050] In a first embodiment of the method according to the present invention, the time t is set in such a way as to be equal to the average time of a washing, that is to say to the transit time of a rack of crockery.

[0051] Advantageously, such kind of approach provides a detergent recovery in the tank at each leakage of a clean rack from the machine.

[0052] In an alternative embodiment, it is possible to perform a more or less frequent detergent restoration, without varying the amounts dispensed. For example, if 1 litre of clean water per minute is utilized for rinsing and a detergent concentration in the tank equal to 10 grams/litre have to be maintained, to compensate the clean water that continuously falls in the tank, 10 grams per minute or 5 grams every half minute or 30 grams every 3 minutes have to be dispensed without varying the dosing concentration nor the detergent consumption. In particular, more frequent is the dosing, more time the concentration degree of detergent in the washing tank is maintained constant. The user can thus advantageously program the parameter t in order to obtain the dosing frequency more suitable for his specific application.

[0053] At the end of the t period, the dosing system based on the method according to the present invention, therefore, it will activate automatically the detergent dosing pump, preferably with a value of maximum speed of the pump, for the time required for dosing a detergent amount obtained from the product defined above.

[0054] As regards the rinse aid dosing, at the first loading conditions, the dosing is not performed. The rinsing water containment boiler remains in fact loaded with water and rinse aid dosed in the last rinse phase before switching off the machine, for example the last rinse phase of the day before. In case of absolute first actuation of the machine, when the containment boiler is empty, the rinse aid dosing is still performed at the first rinsing stage.

[0055] In particular, at a rinsing signal, the rinse aid dosing is carried out taking into account the flow rate of the water used in the rinsing phase. The rinse aid is inserted in the duct that carries cold water to the containment boiler. Here the water is heated to a specific temperature T to ensure that the added rinse aid is correctly activated and the mixture of water and rinse aid can therefore be used for the crockery rinsing. The rinse aid inside the boiler has to be recovered during the rinsing cycle to ensure that the water and rinse aid mixture inside the boiler is always in suitable proportions to ensure optimal efficiency of the rinsing operations.

RINSE Flow Rate=Rinsing Water Flow Rate*Desired RINSE Concentration

[0056] Advantageously, the method according to the invention also provide in an automatic way the activation mode of the rinse aid pump, required to obtain a correct dosing of this chemical.

[0057] In fact, by a knowledge of the volumetric flow rate of the water used for rinsing (defined in litres/second), and thus also the flow rate of clean water that at every second enters in the boiler until the RINSE signal is active, and defined the rinse aid concentration which has to be maintained in the boiler (defined in grams/litre by the manufacturer of the chemical product), the dosing system based on the method according to the present invention adjust automatically the speed of the rinse aid dosing pump, in such a way as to ensure the flow rate of the chemical product required to maintain constant the concentration of the rinse aid in the boiler. For example, at every second the system injects in the boiler the rinse aid quantity required for adding the correct amount of chemical to the clean water entering in the boiler at the same time.

[0058] As shown in the graphs of FIG. 1, as regards the detergent dosing, the method according to the present invention provides that, during a regular operation of the dishwasher (RINSE signal active) the dosing device, or the detergent dosing pump, is activated periodically at the end of the time interval t to inject in the tank the amount of chemical product calculated as described above. If the dishwasher were to be stopped for any reason (RINSE signal inactive) the internal counter is paused, and then continued his counting from the point at which it had arrived, as soon as the dishwasher starts (RINSE active signal).

[0059] Therefore, advantageously, the method according to the present invention comprises a suspending step for suspending a counter of the recovery time interval t at an interruption of the detection phase of the rinse signal, and a reactivation phase of the counter starting from a time t.sub.s characteristic of the suspension phase, at a new detection of said rinsing signal.

[0060] Again, when the internal counter reaches a new time interval t of the set recovery time, a new dosing calculated as described above has to be done.

[0061] As regards the rinse aid instead, the dosing device, or the rinse aid dosing pump, is directly controlled by the rinse signal and until the latter is active, constantly doses chemical product into the water at the inlet of the boiler, as described above, or with a flow rate automatically calculated in such a way as to ensure the right concentration of chemical product in the clean water, which is fed into the boiler in a continuous manner.

[0062] If the machine is stopped for any reason (RINSE signal inactive) also the rinse aid dosing pump stops, and then starts again as soon as the dishwasher is reactivated again (RINSE signal active).

[0063] In this way, advantageously, even in case of malfunction, the delivery of the optimal and strictly necessary amount of product, so neither higher nor lower than the amount required for an efficient operation of the dosing system, is always guaranteed.

[0064] The present invention also includes an implementation of the described method via a computer program.

[0065] Advantageously, the computer program may be stored on a memory medium, for example readable by a programmable electronic device.

[0066] Furthermore, the computer program can be implemented through the development of software that can be supported by any programmable electronic device.

[0067] In the above preferred embodiments have been described and variants of the present invention have been suggested, but it is to be understood that the skilled in the art can make modifications and changes, without so departing from the related scope of protection, as defined by the attached claims.