Patent Application
20110017240
The invention relates to a conveyor dishwasher and to a method of operating such a conveyor dishwasher.
Accordingly, the invention relates, in particular, to a flight-type dishwasher (warewasher) or a rack conveyor dishwasher (warewasher).
Conveyor dishwashers (warewashers) are used commercially. In contrast to domestic dishwashers, in which the wash ware which is to be cleaned remains stationary in the machine as it is cleaned, the wash ware in conveyor dishwashers is transported through various treatment zones of the conveyor dishwasher.
In the case of conveyor dishwashers, the wash ware, for example crockery, pots, glasses, cutlery and other articles which are to be cleaned, is conveyed through a number of treatment zones, for example prewash zone(s), main wash zone(s), postwash or pre-rinse zone(s), final-rinse zone(s) and drying zone(s). However, different types of wash ware, on account of their final usage, their degree of soiling, their shape and the material used, require different treatment parameters for the individual process steps. Conveyor dishwashers nowadays, however, do not usually differentiate automatically between the types of wash ware, in which case the conventional systems are often designed, as a compromise, such that they can be used for a number of different types of wash ware.
U.S. Pat. No. 6,530,996 B2 describes a rack conveyor dishwasher in which the wash ware which is to be cleaned is fed to the respective treatment zones of the rack conveyor dishwasher in a state in which it is pre-sorted in racks. This conventional conveyor dishwasher provides sensors which can determine the type of wash ware which is to be cleaned by virtue of an identifying feature provided on the rack being sensed. A suitable (dish)washing programme of the conveyor dishwasher is selected in dependence on the identifying feature sensed.
DE 196 08 030 C1 discloses a further conveyor dishwasher in which, depending on the type and soiling of the wash ware which is to be cleaned in the individual treatment zones of the conveyor dishwasher, additional spray systems are switched on or off in order to change the distance in the treatment zones over which the wash ware is subjected to action.
It is already known in the case of a conveyor dishwasher from DE 10 2005 021 101 A1 for additional spray nozzles to be switched on and off in dependence on the transporting speed of the wash ware in the dishwashing zone of the conveyor dishwasher, in order thus to reduce the water consumption for final-rinse purposes. Sensors which sense the presence of crockery at the entrance to the conveyor dishwasher are provided here, the system automatically reducing the transporting speed when the quantity of wash ware passing into the conveyor dishwasher decreases.
The present invention is intended to achieve the object of providing a conveyor dishwasher which has at least one wash zone, at least one final-rinse zone and also a control arrangement and which, despite the reduction in the consumption of resources (clean water, chemicals and energy) during operation, can provide good treatment results for all types of wash ware. The intention is also to achieve the object of specifying a corresponding method of operating such a conveyor dishwasher.
On the one hand, providing a wash-ware detector makes it possible for the type of wash ware which is to be treated to be sensed automatically. On the other hand, it is possible to select automatically, for each type of wash ware sensed, an optimum treatment programme in at least one of the treatment zones of the conveyor dishwasher, and to set the process parameters associated with the treatment programme selected. The consumption of clean water, chemicals and energy can be reduced by the resulting optimum adaptation of the process parameters in relation to the respective treatment zones.
In order for it to be possible for the individual programme sequences in the treatment zones of the conveyor dishwasher to be adapted as optimally as possible to the type of wash ware sensed, the invention provides that the control arrangement assigns each type of wash ware which is to be treated in the treatment zones of the conveyor dishwasher to a previously defined or definable wash-ware group. For each wash-ware group, in turn, there is a defined treatment programme by which the wash ware of the type assigned to this wash-ware group is to be treated in at least one of the treatment zones of the conveyor dishwasher, for example in a prewash zone, in a main-wash zone, in a postwash or pre-rinse zone, in a final-rinse zone and/or in a drying zone.
The defined treatment programme for each wash-ware group is preferably a treatment programme which is adapted optimally in respect of economics. Accordingly, the invention makes it possible for the process parameters of the conveyor dishwasher to be automatically adapted optimally to the respective type of wash ware which is to be treated.
The invention thus makes it possible for the types of wash ware which are to be treated to be differentiated automatically and for the treatment parameters for the individual process steps to be adapted, during cleaning of the wash ware, to the wash-ware group to which the type of wash ware which is to be cleaned is assigned.
The “type of wash ware” is understood here as the type of wash ware which is to be treated and/or to be cleaned. The type of wash ware depends, for example, in particular on the size, the shape and/or the material of the wash ware which is to be cleaned.
In a preferred realization of the solution according to the invention, it is provided that at least the following wash ware can be detected with reference to the type of wash ware sensed:
The invention is based on the finding that the process parameters which are to be selected for effective treatment and/or cleaning in the individual treatment zones depend on the type of wash ware which is to be treated. The different types of wash ware here require suitable treatment programmes by which the wash ware is to be treated, for example, in the wash zones (prewash, main-wash, postwash zones) of the conveyor dishwasher. The treatment programmes are coordinated, in particular, from the point of view of a volume-flow quantity of wash liquid which is to be sprayed per unit of time in at least one of the wash zones and from the point of view of a nozzle pressure by which the wash liquid is sprayed in at least one of the wash zones. Thus for example lightly soiled crockery items, such as trays or drinking glasses, in contrast to heavily soiled crockery items with burnt-on, difficult-to-remove food residues, e.g. cooking utensils, heat-preserving containers, baking tins, etc., require only a comparatively small volume-flow quantity of wash liquid sprayed per unit of time in the wash zone and only a comparatively low nozzle pressure for spraying the wash liquid in the wash zone.
On the other hand, the different types of wash ware also require treatment programmes which are coordinated from the point of view of a volume-flow quantity of final-rinse liquid which is to be sprayed per unit of time in the final-rinse zone and by which the wash ware is treated in the final-rinse zone of the conveyor dishwasher.
The solution according to the invention makes it possible for the dishwashing mechanics of at least one wash zone, i.e. the volume-flow quantity of wash liquid which is to be sprayed per unit of time in the wash zone, and the nozzle pressure by which the wash liquid is sprayed in the wash zone, to be adapted optimally to the type of wash ware which is to be treated in the wash zone.
As an alternative, or in addition, the solution according to the invention also makes it possible for example for the volume-flow quantity of final-rinse liquid which is to be sprayed per unit of time in the final-rinse zone to be adapted optimally to the type of wash ware which is to be treated in the final-rinse zone.
As a result, “over-washing” for example of only lightly soiled crockery items, such as trays or drinking glasses, can be prevented in a straightforward but effective manner, in which case no more resources of energy, water, chemicals, etc. than necessary are used during the process for cleaning such merely lightly soiled crockery items.
It is thus possible to reduce the consumption of clean water sprayed onto the wash ware, for example, in the final-rinse zone in pure form or in a state in which it has been mixed with further additives. The reduced consumption of clean water in the conveyor dishwasher means that it is also possible to reduce the consumption of chemicals, in particular rinse aid and/or detergent, without resulting in any change in the concentration of chemicals in the respective liquid. Feeding a smaller quantity of clean water means that the quantity of water which is to be heated is smaller, as a result of which energy can be saved.
The object on which the invention is based is further achieved by a method of operating a conveyor dishwasher which has at least one wash zone and at least one final-rinse zone and also a control arrangement. The invention provides that the method implements the method steps which are specified hereinbelow. In the first instance, the type of wash ware which is to be treated is sensed. Thereafter, a previously defined or definable treatment programme by which the type of wash ware assigned to the wash-ware group is to be treated in the at least one wash zone is selected automatically for each wash-ware group, and the process parameters associated with the treatment programme selected are set. As an alternative, or in addition to, the last-mentioned method step, a previously defined or definable treatment programme by which the type of wash ware assigned to the wash-ware group is to be treated in the at least one final-rinse zone is selected automatically for each wash-ware group, and the process parameters assigned to the treatment programme selected are set.
The invention will be described hereinbelow with reference to the drawings and using preferred embodiments by way of example.
In the drawings:
The conveyor dishwasher 1 of
In the case of the conveyor dishwasher 1 which is illustrated in
As seen in the transporting direction 3, the wash ware, which is either accommodated directly on the conveying belt 2 or is retained by racks, runs, in the transporting direction 3, through the inlet tunnel 5, the following prewash zone 6, the first main-wash zone 7, the second main-wash zone 8, the postwash zone 9, the final-rinse zone 10 and a drying zone 26 into an outlet section 25.
The abovementioned treatment zones 6, 7, 8, 9 and 10 of the conveyor dishwasher 1 are each assigned spray nozzles 11, 12, 13, 14 and 15 via which liquid is sprayed onto the wash ware which is transported through the respective treatment zones 6, 78, 9 and 10 by the transporting arrangement 2. Each treatment zone 6, 7, 8, 9 and 10 is assigned a tank 16, 18, 20 and 22 in which sprayed liquid is accommodated and/or in which liquid for the spray nozzles of the relevant zones is provided. In the case of the conveyor dishwasher 1 which is illustrated in
Some of the final-rinse liquid sprayed is transported from zone to zone, counter to the transporting direction 3 of the wash ware, via a cascade system. The rest is channelled directly into the prewash tank 16 via a valve 77 and a bypass line 88.
The final-rinse liquid sprayed is collected in the tank 20 (postwash tank 20) of the postwash zone 9, from which it is delivered to the spray nozzles 14 (postwash nozzles 14) of the postwash zone 9 via a pump system. In the postwash zone 9, wash liquid is rinsed off from the wash ware. The liquid which accumulates here flows into the wash tank 18b of the second main-wash zone 8, is usually provided with a detergent and is sprayed onto the wash ware by a pump system via the nozzles 13 (wash nozzles 13) of the second main-wash zone 8. From the wash tank 18b of the second main-wash zone 8, the liquid flows into the wash tank 18a of the first main-wash zone 7. From there, the liquid is sprayed onto the wash ware anew via a further pump system, via the wash nozzles 12 of the first main-wash zone 7. From the wash tank 18a of the first main-wash zone 7, the liquid then flows into the prewash tank 16 of the prewash zone 6. The liquid in the prewash tank 16 is sprayed onto the wash ware via a pump system, via the prewash nozzles 11 of the prewash zone 6, in order for coarse dirt to be removed from the wash ware.
The individual dishwashing systems of the treatment zones 6, 7, 8, 9 and 10 ensure that the wash ware is sprayed both from the top side and from the underside.
The respective zones 6, 7, 8, 9 and 10 of the conveyor dishwasher 1 can be separated from one another via separating curtains 37. In the case of the embodiment which is illustrated in
The final-rinse zone 10 is followed, in the transporting direction 3 of the wash ware, by the already mentioned drying zone 26. In the drying zone 26, the wash ware is dried by way of dry and heated air in order for the moisture located on the wash ware to be blown off and dried up. In order to keep the moisture content of the air in a range which is favourable for drying purposes, it is conceivable, for example, to feed ambient air via an opening, for example through the exit opening for the wash ware. The hot and moisture-laden air is withdrawn from the drying zone 26 via a further opening, for example with the aid of a fan 31. It is advantageous here if the exhaust-air stream from the drying zone 26 passes a heat-recovery device 30, in which a condenser may be provided. The heat-recovery device 30 serves for recovering at least some of the heat energy contained in the exhaust air.
In the case current flight-type/rack conveyor dishwashers, the wash ware is conveyed through a number of treatment zones, for example prewash zones, main-wash zones, postwash zones, final-rinse zones and drying zones. As already indicated, different treatment parameters are required by different types of wash ware in the treatment zones of the conveyor dishwasher. The conveyor dishwashers which are known at present, however, do not differentiate automatically between the types of wash ware which are to be treated, in which case the conventional systems are usually designed, as a compromise, such that they can be used more or less efficiently for a number of types of wash ware. This approach means that usually significantly more resources (energy, water, chemicals, etc.) than would actually be necessary are used in order to treat the wash ware.
The conveyor dishwasher 1 according to the invention—as is illustrated, for example, in FIG. 1—is characterized in that a wash-ware detector 34 is provided, and this serves to sense the type of wash ware which is to be treated in the conveyor dishwasher 1. The term “wash-ware detector” used here is to be understood as any detector which is designed to sense and/or to determine the type of wash ware which is to be treated in the conveyor dishwasher 1. It is conceivable here, in particular, for the wash-ware detector 34 to have at least one detector device 35 which can sense the size, the shape and/or the material of the wash ware which is to be treated in the conveyor dishwasher 1.
In a preferred realization of the conveyor dishwasher 1 according to the invention, the wash-ware detector 34 has at least one preferably optically, inductively or capacitively operating detector device 35, in which case the size, the shape and/or the material of the wash ware can be directly sensed for the purpose of identifying the type of wash ware. The detector device 35, however, may also be formed by other types of detector, for example inductively operating proximity sensors, light sensors, light curtains, laser scanners, 3D lasers, cameras, rotary transducers, etc.
The wash-ware detector 34 is preferably arranged at the inlet 4 of the conveyor dishwasher 1, in order for it to be possible to sense the type of wash ware which is to be fed to the individual treatment zones 6, 7, 8, 9, 10 and 26 of the conveyor dishwasher 1. It would, of course, also be conceivable, however, for the wash-ware detector 34 to be arranged in a suitable manner in the interior of the conveyor dishwasher 1.
The conveyor dishwasher 1 according to the present invention also has a control arrangement 36, which is illustrated schematically in
As is illustrated in the drawings, the control arrangement 36 is connected to the wash-ware detector 34 in particular via a suitable communication connection, in order for the type of wash ware which is sensed by the wash-ware detector 34 as it is fed to the conveyor dishwasher 1 to be interrogated continuously or at predetermined times and/or as predetermined events occur.
The control arrangement 36 is designed such that the wash ware which is to be treated can be detected automatically with reference to the type of wash ware sensed by the wash-ware detector 34. The control arrangement 36 can preferably detect at least the following wash ware automatically:
For the case where the control arrangement 36 does not detect the wash ware with reference to the type of wash ware sensed, the relevant wash ware is identified as “other wash ware”.
The solution according to the invention is distinguished not just by the automatic sensing of the type of wash ware and by the automatic detection of the wash ware which is to be treated, but also by the additional functionality of the control arrangement 36, according to which the latter is designed to assign each type of wash ware sensed to a previously defined or definable wash-ware group.
This assigning capability ensures that wash ware of different types which can be treated with identical process parameters in the respective treatment zones 6, 7, 8, 9, 10 and 26 of the conveyor dishwasher 1 is combined into a wash-ware group. It has been found here that in order for, for example, plates produced from porcelain or from a porcelain-like material and cups and bowls produced from porcelain, a porcelain-like material, glass or a glass-like material to undergo prewashing, main washing, final rinsing and drying in the treatment zones 6, 7, 8, 9, 10 and 26, it is possible to select the same or more or less identical setting parameters in order to allow optimum treatment of these types of wash ware while making efficient use of resources.
In the case of trays, or tray-like articles, produced from a plastic material being treated, in contrast, it is possible to dispense with a prewash altogether, and the volume-flow quantity of final-rinse liquid which is sprayed per unit of time in the final-rinse zone 10 can be reduced in comparison with the treatment of, for example, plates, cups or bowls.
In the case of containers, in particular GN containers, pots and pans produced from a metal, in particular from stainless steel, in contrast, both the quantity of wash liquid which is sprayed per unit of time in the wash zones 6, 7, 8 of the conveyor dishwasher 1 and the nozzle pressure by which the wash liquid is sprayed in the wash zones 6, 7, 8 should be increased in comparison with other types of wash ware, in order for it to be possible to achieve effective cleaning. In addition to this, it is conceivable, during the treatment of the containers, pots and pans, to reduce the transporting speed at which these types of wash ware are transported through the respective treatment zones 6, 7, 8, 9, 10 and 26 of the conveyor dishwasher 1, in order thus for the respective periods of contact in the individual treatment zones to be increased. This, in turn, makes it possible to set to a relatively low value the volume-flow quantity of final-rinse liquid which is sprayed per unit of time in the final-rinse zone 10 of the conveyor dishwasher 1.
Cutlery and items of cutlery produced from metal, and in particular from stainless steel, require, for treatment in the prewash zone 6 and in the main-wash zones 7, 8, of the conveyor dishwasher 1, preferably the same or similar process parameters as are used in the prewashing and main washing of plates, cups or bowls.
However, in comparison with the treatment of plates, cups or bowls in the final-rinse zone 10 of the conveyor dishwasher 1, the type of wash ware to which cutlery and items of cutlery belong preferably requires an increased volume-flow quantity of final-rinse liquid per unit of time.
If the wash-ware detector 34 senses drinking glasses produced from glass or a glass-like material, it is sufficient for the treatment of this type of wash ware to dispense with a prewash in the prewash zone 6, since this type of wash ware would otherwise be soiled or adversely affected in addition by the usually already relatively heavily soiled wash liquid which is sprayed in the prewash zone 6. It is nevertheless conceivable, for the treatment of this type of wash ware (drinking glasses), for just one of the two main-wash zones 7, 8 which are illustrated in
In order also to prevent renewed soiling of this type of wash ware (drinking glasses) in the postwash zone 9 of the conveyor dishwasher 1, it is further preferred if, for the treatment of this type of wash ware, the postwash zone 9 is switched off, for example by the feed of postwash liquid to the postwash zone 9 being suppressed. It is optionally possible for the lack of pump-action dishwashing in the postwash zone 9 to be compensated for by additional clean-water dishwashing in the final-rinse zone 10, for example by an increased volume-flow quantity of final-rinse liquid being sprayed per unit of time in the final-rinse zone 10.
In order for it to be possible to select optimum process parameters for treating the respective types of wash ware, the following assignments are preferably made with the aid of the control arrangement 36:
The abovementioned wash-ware groups have already been defined beforehand. It is, of course, also conceivable, however, for the wash-ware groups to be altered by the operator of the conveyor dishwasher 1 if required.
The solution according to the invention is distinguished in that the control arrangement 36 is designed to select automatically, for each wash-ware group, a defined (previously defined or later defined by the user) treatment programme by which the type of wash ware assigned to the wash-ware group is to be treated in the prewash zone 6, in the main-wash zones 7, 8 and/or in the postwash zone 9, and to set the process parameters associated with the treatment programme selected. As an alternative, or in addition to this, the control arrangement 36 is also designed to select automatically, for each wash-ware group, a previously defined or definable treatment programme by which the type of wash ware assigned to the wash-ware group is to be treated in the final-rinse zone 10, and to set the process parameters associated with the treatment programme selected.
It is conceivable, for this purpose, for the control arrangement 36 to have, for example, a storage device (e.g., memory—not illustrated explicitly in
That preferred realization of the conveyor dishwasher 1 according to the invention which is illustrated in
On the other hand, the preferred realization of the conveyor dishwasher 1 provides that the control arrangement 36 sets automatically to a previously defined high value of greater than, for example, 650 l/min, as it detects wash ware belonging to the second wash-ware group, the volume-flow quantity of wash liquid which is to be sprayed per unit of time in each case in the two main-wash zones 7, 8. The nozzle pressure by which the wash liquid is sprayed in the two main-wash zones 7, 8 should likewise assume a high value here of, for example, greater than 0.4 bar.
As far as the treatment of the wash ware in the final-rinse zone 10 is concerned, the preferred realization of the control arrangement 36 provides that the control arrangement 36 sets automatically to a previously defined average value of, for example, 170 to 200 l/h, as it detects wash ware belonging to the first wash-ware group, a volume-flow quantity of final-rinse liquid which is to be sprayed per unit of time in the final-rinse zone 10. When it detects wash ware belonging to the second or third wash-ware group, in contrast, the control arrangement 36 is preferably designed to set automatically to a previously defined low value of, for example, less than 170 l/h the volume-flow quantity of final-rinse liquid which is to be sprayed per unit of time in the final-rinse zone 10. As it detects wash ware belonging to the fourth or fifth wash-ware group, in contrast, the control arrangement 36 sets automatically to a previously defined high value of, for example, greater than 200 l/h the volume-flow quantity of final-rinse liquid which is to be sprayed per unit of time in the final-rinse zone 10.
The values mentioned above are examples, which are not to be considered as restrictive.
It is conceivable in principle, in the case of the conveyor dishwasher 1 which is illustrated in
The invention is not restricted to the embodiments of
In particular, it is conceivable, for example, for the conveyor dishwasher 1 according to the present invention also to have a steaming zone (not illustrated explicitly in the drawings), in which case the control arrangement 36 may be designed to provide a setting automatically, for each wash-ware group, where the feed of steam to the steaming zone is switched on or off, the feed of steam to the steaming zone preferably being switched on automatically upon detection of wash ware belonging to the second wash-ware group.
It is likewise conceivable, in principle, for the conveyor dishwasher 1 according to the invention to have a direct-action detergent-spray system, in which case the control arrangement 36 is designed to provide a setting automatically, for each wash-ware group, where the feed of detergent to the direct-action detergent-spray system is switched on or off, or the quantity of detergent is controlled in dependence on the wash-ware group.
It is nevertheless conceivable for the control arrangement 36 to be designed to select automatically, for each wash-ware group, a previously defined or definable treatment programme by which the type of wash ware assigned to the wash-ware group is to be treated in the drying zone 26, and to set the process parameters associated with the treatment programme selected.
It is preferred, in principle, if the control arrangement 36 selects and correspondingly defines, optionally automatically, the process parameters which are optimum for the treatment of the respective types of wash ware, in order to make it possible, in principle, for the user of the conveyor dishwasher also to be capable of manually setting or altering the process parameters which prevail in the respective treatment zones.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 014 318.9 | Mar 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2009/035950 | 3/4/2009 | WO | 00 | 9/10/2010 |
