EP2775895B1

EP2775895B1 - Ware washer with at least one washing system realized as a recirculating circuit

Info

Publication number: EP2775895B1
Application number: EP12780987.9A
Authority: EP
Inventors: Markus Heidt; Harald Disch; Harry Braun
Original assignee: Premark FEG LLC
Current assignee: Premark FEG LLC
Priority date: 2011-10-20
Filing date: 2012-10-16
Publication date: 2016-01-13
Anticipated expiration: 2032-10-16
Also published as: WO2013059141A2; CN103889298A; AU2012326378A1; WO2013059141A3; AU2012326378B2; EP2775895A2

Description

The invention relates to a ware washer with a wash system recirculation circuit and, in particular, the invention relates to an industrial ware washer for crockery or utensils, which is realized as an automatic programmable machine or as a conveyor ware washer.
The invention also relates to a method for operating such a ware washer.
The invention is thus directed to a method for operating a ware washer and to a ware washer itself having at least one washing system realized as a recirculating circuit. The washing system has a nozzle system with at least one wash nozzle for spraying washing fluid onto the items to be washed, a washing tank for collecting at least part of the sprayed washing fluid and a wash pump for supplying washing fluid collected in the washing tank to the at least one wash nozzle. Also provided in the case of the ware washer according to the invention is a dirt collecting system which is associated with the at least one wash zone and serves to separate dirt particles from the sprayed washing fluid which flows back into the washing tank by means of gravity. Further provided is a dirt discharge pump which is connected or can be connected on the intake side to the dirt collecting system and is connected or can be connected on the delivery side to a dirt discharge pipe system for the discharge, when necessary, of at least part of the washing fluid that has passed into the dirt collecting system and at least part of the dirt particles separated from the washing fluid collected in the washing tank by way of the dirt collecting system.
Ware washers for crockery or utensils according to the invention are either automatically programmable machines in the form of box-type ware washers (also referred to as batch dishwashers) or conveyor ware washers.
Conveyor ware washers are in the form, in particular, of flight-type ware washers or rack conveyor ware washers. Conveyor ware washers are usually used in the industrial sector. In contrast to box-type ware washers, in which the items to be washed remain in a fixed position in the machine during washing, conveyor ware washers have the items conveyed through different treatment zones of the conveyor ware washers.
A conveyor ware washer usually has at least one pre-wash zone and at least one main wash zone, which is arranged downstream of the pre-wash zone(s), as seen in the conveying direction of the items to be washed. Usually at least one post-wash zone or pre-rinse zone is arranged downstream of the main-wash zone(s), and at least one final rinse zone is arranged downstream of the post-wash zone(s), as seen in the conveying direction. As seen in the conveying direction, the items, which are either accommodated directly on the conveying belt or are retained by racks, run, in the conveying direction, usually through an entrance tunnel, the following pre-wash zone(s), main-wash zone(s), post-wash zone(s), final rinse zone(s) and a drying zone into an exit section.
The aforementioned wash zones of the conveyor ware washer are each assigned a washing system which has a wash pump and a line system (wash-line system) which is connected to the wash pump via which washing fluid is supplied to the nozzle system or to the at least one wash nozzle of the nozzle system. The washing fluid supplied to the at least one wash nozzle of the nozzle system is sprayed, in the respective wash zones of the conveyor ware washer, onto the items to be washed, which are conveyed through the respective wash zones by a conveying device of the conveyor ware washer. Each wash zone is assigned a tank, in which the fluid sprayed by the wash nozzles is accommodated and/or in which fluid for the nozzle systems of the relevant treatment zones is supplied.
In the case of the conveyor ware washers which are known customarily from the prior art, final rinse fluid in the form of fresh water, which may be in pure form or have further additives, for example rinse aid, mixed with it, is sprayed onto the items via the spray nozzles of the final rinse zone. At least part of the sprayed final rinse fluid is conveyed from zone to zone, counter to the conveying direction of the items, via a cascade system.
The sprayed final rinse fluid is collected in a tank (post-washing tank) of the post-wash zone, from which it is delivered to the spray nozzles (post-wash nozzles) of the post-wash zone via the wash pump of the washing system belonging to the post-wash zone. In the post-wash zone, washing fluid is rinsed off from the items to be washed. The fluid which accumulates here flows into the washing tank of the at least one main wash zone, which is arranged upstream of the post-wash zone, as seen in the conveying direction of the items to be washed. Here, the fluid is usually provided with a detergent and is sprayed onto the items by a pump system (wash pump), which belongs to the washing system of the main-wash zone, via the nozzles (wash nozzles) of the main-wash zone. From the washing tank of the main-wash zone, the fluid then flows - if there is no further main wash zone provided - into the pre-washing tank of the pre-wash zone. The fluid in the pre-washing tank is sprayed onto the items via a pump system (pre-wash pump), which belongs to the washing system of the pre-wash zone, via the pre-wash nozzles of the pre-wash zone, in order for coarse soiling to be removed therefrom.
Conveyor ware washers are usually provided with wash pumps by means of which the final rinse fluid which is to be sprayed in the final rinse zone is supplied to the line system of the final rinse zone. This ensures, in particular, a more or less constant volume flow of the final rinse fluid in the final rinse zone. However, it is also conceivable to utilize the on-site line pressure - for example the pressure of the fresh-water supply - in order to channel the final rinse fluid to the line system of the final rinse zone. In the latter case, an activatable valve may be provided between the line system and the spray nozzles of the final rinse zone in order for it to be possible to interrupt the supply of final rinse fluid to the spray nozzles at certain times or altogether.
Box-type ware washers are ware washers which can be loaded and unloaded manually. These include hood-type ware washers or front-loader ware washers. Front-loader ware washers may be in the form of under-counter machines, counter-top machines or free-standing front-loader ware washers.
A ware washer realized in the form of a box-type ware washer usually has a treatment chamber for washing items. A washing system realized as a recirculating circuit is usually formed in this treatment chamber. The treatment chamber usually has arranged beneath it a washing tank, in which fluid can flow back out of the treatment chamber under gravitational force. The washing tank contains washing fluid, which is usually water, to which, if appropriate, detergent can be supplied.
The washing system has a wash pump, a line system, which is connected to the wash pump, and a nozzle system with at least one wash nozzle. The washing fluid located in the washing tank can be delivered by the wash pump, via the line system, to the at least one wash nozzle and sprayed in the treatment chamber, by this at least one wash nozzle, onto the items to be washed. The sprayed washing fluid then flows back into the washing tank under gravitational force.
Conventional ware washers realized as box-type ware washers normally operate in two main process steps, that is to say in the first instance washing with washing fluid and then final rinsing with heated fresh water, which has rinse aid metered into it. The washing fluid contains water and metered detergent. In order for it to be possible to carry out these two process steps, an industrial ware washer realized as a box-type ware washer is usually provided with two independent fluid systems, which are completely separate from one another. One of these two fluid systems is a washing-fluid circuit, which is responsible for washing the items and makes use of already used fluid from the washing tank. The other fluid system is a final rinse fluid system, which usually has a boiler for heating fresh water.
The main task of final rinsing with a final rinse fluid is that of removing the washing fluid located on the items. In addition, the final rinse fluid which flows off into the washing tank during final rinsing serves for regenerating the washing fluid in the washing tank.
Before new fresh water is supplied for final rinsing, usually the same quantity of washing fluid is pumped out of the washing tank into the on-site waste water network.
A particular type of industrial ware washer in the form of a box-type ware washer is constituted by hood-type ware washers. The treatment chamber thereof for washing items is enclosed by a hood. The hood can be raised upward, in order for the treatment chamber to be loaded, and then lowered again, in order for the items to be treated. Hood-type ware washers are provided, virtually without exception, with an inflow table and an exit table. The inflow table, in many cases, is realized as a pre-cleaning station for pre-cleaning the items by rinsing and/or by manual removal of soiling from the items, prior to the latter being pushed into the hood-type ware washer in a rack. The pre-cleaning by preliminary rinsing normally takes place manually. The preliminary rinsing for the pre-cleaning is usually carried out using on-site, cold or pre-heated fresh water. In some cases, an additional cleaning chemical is also used for preliminary rinsing. The exit table serves for drying purposes and for unloading the racks of items.
Irrespective of whether the ware washer is realized as a box-type ware washer or conveyor ware washer, it is usually the case that the items are subjected to a manual preliminary cleaning operation and manual pre-washing before being supplied to the ware washer. This is intended to prevent premature contamination of the washing fluid as a result of coarse soiling, such as, for example, serviettes or food leftovers.
Document WO 2011/043864 A2 discloses one such ware washers in the form of a coveyor-type ware washer.
The invention is intended to achieve the object of increasing the through-put capacity of a ware washer of the type mentioned in the introduction. In particular, the intention is to specify a method and a ware washer by means of which a relatively large quantity - in comparison with conventional machines - of items can be effectively washed per unit of time without additional personnel being necessary here in order to load and unload the machine.
Accordingly, a ware washer which has at least one washing system realized as a recirculating circuit is proposed, wherein the at least one washing system has a nozzle system with at least one wash nozzle, a washing tank and a wash pump for supplying washing fluid collected in the washing tank to the at least one wash nozzle. A dirt collecting system is associated with the at least one washing system and is realized in order to separate dirt particles from the sprayed washing fluid which flows back into the washing tank by means of gravity. A dirt discharge pump is connected or can be connected on the intake side to the dirt collecting system and is connected or can be connected on the delivery side to a dirt discharge pipe system for the discharge from the wash zone, where necessary, of at least part of the washing fluid that has passed into the dirt collecting system and at least part of the dirt particles separated from the washing fluid collected in the washing tank by way of the dirt collecting system.
According to the invention, the ware washer also has a waste water pump which is connected or can be connected on the intake side to the washing tank and is connected or can be connected on the delivery side to the waste water pipe system for the pumping out, when necessary, of at least part of the washing fluid collected in the washing tank; said waste water pump may be activated in coordination with the dirt discharge pump.
The advantages which can be achieved by the solution according to the invention are obvious: By providing, on the one hand, a dirt collecting system and, on the other hand, a pump-out system comprising the waste water pump, which is connected or can be connected on the intake side to the washing tank and is connected or can be connected on the delivery side to the waste water pipe system, it is possible to automate the pre-washing operation, which is usually carried out manually outside the wash zone, and to assign this function to the ware washer. By virtue of this function being performed by the ware washer, it is thus possible to dispense with the working step of the items being subjected to manual pre-cleaning. This reduces working times and thus increases the through-put capacity of the ware washer.
Tests carried out within the context of the invention showed that, in the case of a conventional hood-type ware washer, which can usually be operated only by a single individual, it is possible to achieve a capacity increase of around 20% using the solution according to the invention. This is attributable, in particular, to the fact that the additional machine function of integrated pre-washing makes it possible to dispense with the pre-washing operation which has to be carried out manually for conventional machine loading. In the case of conventional ware washers, such a capacity increase can be achieved only when more personnel are used to operate the ware washer.
In the case of the method according to the invention, during a pre-wash phase, the wash pump of the ware washer is activated in such a manner that at least part of the washing fluid collected in the washing tank is supplied to the at least one wash nozzle in order to allow the items to be prewashed. Then, during a dirt discharging phase, the dirt discharge pump is activated in such a manner that at least part of the dirt particles separated from the washing fluid by way of the dirt collecting system is supplied to the dirt discharge pipe system in order to allow the dirt particles to be discharged from the machine or the wash zone. During a following main wash phase, the wash pump is activated in such a manner that at least part of the washing fluid collected in the washing tank is supplied to the at least one wash nozzle in order to wash the items. Finally, during a pump-out phase, the waste water pump is activated in such a manner that at least part of the washing fluid collected in the washing tank is supplied to the waste water pipe system.
Advantageous developments of the ware washer according to the invention are specified in dependent claims 2 to 12, and advantageous developments of the method according to the invention are specified in dependent claims 14 and 15.
Thus, in a preferred development of the ware washer according to the invention, it is provided that the dirt collecting system has a tank covering sieve and a dirt collecting region for collecting the dirt particles separated from the washing fluid by means of the tank covering sieve. The dirt collecting region is preferably open upward, but is completely closed at the sides. The dirt discharge pipe system here should be connected or connectable to the dirt collecting region.
It is conceivable here for the tank covering sieve to be arranged above the dirt collecting region and to be provided with a run-off inclination in the direction of a supply opening, wherein the upwardly open dirt collecting region should be arranged below the supply opening in such a manner that the dirt particles separated by means of the tank covering sieve can pass into the dirt collecting region by means of the supply opening.
Providing the tank covering sieve, preferably realized as a planar sieve, on the one hand and the dirt collecting system on the other hand ensures that the dirt particles rinsed off from the items in the washing system and the dirt particles otherwise introduced into the washing fluid can be separated effectively from the washing fluid and collected, and concentrated, in the dirt collecting region. Since the dirt collecting region is completely closed at the sides (i.e. fluid-tight), the dirt particles collected in the dirt collecting region are encapsulated in relation to the washing fluid in the washing tank, and therefore even relatively small dirt particles possibly arising as a result of the dirt particles collected in the dirt collecting region being dissolved cannot pass back into the washing fluid accommodated in the washing tank.
It is, on the other hand, provided, in the case of the solution according to the invention, that the dirt collecting region is connected or can be connected to the dirt discharge pipe system via the dirt discharge pump, wherein the dirt particles collected in the dirt collecting region can be removed from the washing system, together with at least part of the washing fluid which has passed into the dirt collecting region of the dirt collecting system, by means of the dirt discharge pipe system. This can reduce the residence time of the dirt particles in the dirt collecting region, and thus in the washing system, and therefore it is no longer possible for dirt to dissolve on account of the recirculation of the washing fluid in the washing system.
Accordingly, it is possible to use the solution according to the invention - despite the pre-cleaning carried out automatically in the machine - to achieve a constant washing result even as the washing time increases, wherein re-contamination of the items by dirt particles in the washing fluid is effectively prevented.
In a preferred realization of the ware washer according to the invention, it is provided that the latter is provided with a control device which is realized to activate, selectively, in a synchronized manner, the wash pump, the dirt discharge pump and the waste water pump. In specific terms, the control device is designed such that, during a pre-wash phase, at least part of the washing fluid collected in the washing tank is supplied to the at least one wash nozzle by means of the wash pump. During a dirt discharging phase, at least part of the dirt particles separated from the washing fluid by way of the dirt collecting system is supplied, together with at least part of the washing fluid which has passed into the dirt collecting system, to the dirt discharge pipe system by means of the dirt discharge pump. During a main wash phase, at least part of the washing fluid collected in the washing tank is supplied to the at least one wash nozzle by means of the wash pump and, during a pump-out phase, at least part of the washing fluid collected in the washing tank is supplied to the waste water pipe system by means of the waste water pump. The control device is preferably realized to activate the dirt discharge pump in dependence on the amount of dirt particles separated from the washing fluid by way of the dirt collecting system.
It is conceivable here, for example, for there also to be provided a device for detecting the fill level in the washing tank, wherein the control device is realized to activate the dirt discharge pump automatically and preferably selectively automatically in dependence on the detected fill level.
In a particularly easy-to-achieve, but nevertheless effective, embodiment, the control device is realized to activate the dirt discharge pump for a previously fixed duration, wherein this previously fixed duration depends on the detected fill level. As an alternative, or in addition, it is conceivable if the control device has a comparator for comparing the detected fill level with at least one previously fixed or fixable threshold value, wherein the control device activates the dirt discharge pump for a previously fixed duration dependent on the result of the comparison carried out by means of the comparator.
As an alternative to this, it is conceivable for the control device to activate the dirt discharge pump until a previously fixed volume of washing fluid, or washing fluid with separated dirt particles, is pumped out by means of the dirt discharge pump, wherein the previously fixed volume is dependent on the detected fill level. With this embodiment too, it is conceivable in addition, or as an alternative, for the control device to have a comparator in order to compare the detected fill level with the at least one previously fixed or fixable threshold value, wherein the control device activates the dirt discharge pump until a previously fixed volume of washing fluid, or washing fluid with dirt particles, which is dependent on the result of the comparison carried out by means of the comparator, is pumped out.
In this context, it is provided, according to a development of the ware washer according to the invention, that the dirt discharge pump is assigned a device which serves to determine a volume of washing fluid, or washing fluid with separated dirt particles, discharged by the dirt discharge pump.
The device used for detecting the fill level in the washing tank is, for example, a fill level sensor which is arranged in the washing tank and is designed to detect the current fill level in the washing tank continuously or at predetermined times and/or in the case of predetermined events. It is conceivable here, for example, to provide a pressure sensor which is arranged in the washing tank and detects a hydrostatic pressure in the washing fluid accommodated in the washing tank at the level of the pressure sensor continuously or at predetermined times or in the case of predetermined events, wherein the detected hydrostatic pressure value is converted into a corresponding fill level value by means of the control device.
The device used to detect the fill level in the washing tank may also be, for example, a fill level limit switch, which is arranged in the washing tank and is designed to detect whether the fill level in the washing tank falls below a previously fixed fill level threshold value. In the case of this embodiment, it is advantageous if the control device is realized to activate the dirt discharge pump automatically and preferably selectively automatically when the previously fixed fill level threshold value is not met.
In a preferred development of the last-mentioned embodiment, the device used for detecting the fill level in the washing tank is constituted by at least two fill level limit switches which are arranged in the washing tank and are designed, in such a manner that they can detect whether the fill level in the washing tank falls below a first and/or a second previously fixed fill level threshold value. In the case of this realization of the ware washer according to the invention, it is advantageous if the control device is realized to activate the dirt discharge pump for a first previously fixed or fixable duration when it is detected, by means of the at least two fill level limit switches arranged in the washing tank, that only the first fill level threshold value is not met. Furthermore, the control device here should be realized in such a manner that the dirt discharge pump is activated for a second previously fixed or fixable duration when it is detected, by means of the at least two fill level limit switches which are arranged in the washing tank, that, in addition to the first, also the second fill level threshold value is not met. The first fill level threshold value here corresponds to a level which lies above the second fill level threshold value.
As an alternative to the last-mentioned embodiment, it is conceivable if the device for detecting the fill level in the washing tank is constituted by two fill level limit switches, wherein these at least two fill level limit switches are arranged in the washing tank and designed in such a manner that they detect whether the fill level in the washing tank falls below a first and/or second previously fixed fill level threshold value. It is advantageous here if the control device is realized to activate the dirt discharge pump until a previously fixed first volume of washing fluid, or a washing fluid with dirt particles, is pumped out by means of the dirt discharge pump when it is detected, by means of the at least two fill level limit switches, that only the first fill level threshold value is not met. In addition, the control device should be realized to activate the dirt discharge pump until a previously fixed second volume of washing fluid is pumped out by means of the dirt discharge pump when it is detected, by means of the at least two fill level limit switches, that the second fill level threshold value is also not met.
In addition, the solution according to the invention provides an effective method for discharging dirt particles from the washing fluid, and therefore it is possible to realize a longer service life for the washing fluid than is the case with conventional solutions. This makes it possible to use the washing fluid for cleaning a greater quantity of crockery before it has to be changed over. This reduces, in particular, the amount of fresh water, detergent and heating energy used.
Exemplary embodiments of the solution according to the invention will be explained in more detail hereinbelow with reference to the accompanying drawings, in which:

figure 1: shows, schematically, a first embodiment of a ware washer realized in the form of a conveyor ware washer;
figure 2: shows, schematically, a second embodiment of a ware washer realized in the form of a conveyor ware washer;
figure 3: shows a hydraulics diagram for a washing system of a ware washer which is realized as a conveyor ware washer and has an integrated pre-wash function and dirt discharge means;
figure 4: shows a hydraulics diagram for a washing system of a first embodiment of a ware washer which is realized as a box-type ware washer and has an integrated pre-wash function and dirt discharge means;
figures 5a-c: show program-sequence descriptions for a ware washer with an integrated pre-wash function and dirt discharge means; and
figure 6: shows a hydraulics diagram for a washing system of a second embodiment of a ware washer which is realized as a box-type ware washer and has an integrated pre-wash function and dirt discharge means.

Figure 1 shows a schematic longitudinal-section view of an example of a conveyor ware washer 50 which is realized in accordance with the teaching of the present invention. The conveyor ware washer 50 according to the illustration in figure 1 has a pre-wash zone 51 and a main wash zone 52, which is arranged downstream of the pre-wash zone 51, as seen in the conveying direction T of the items to be washed (not illustrated in figure 1) In the case of the conveyor ware washer 50 illustrated in figure 1, a post-wash or pre-rinse zone 53 is arranged downstream of the main wash zone 52, and a final rinse zone 54 is arranged downstream of the post-wash or pre-rinse zone 53, as seen in the conveying direction T.
In the case of the conveyor ware washer 50 illustrated, at least the pre-wash zone 51 and the main wash zone 52 are each realized as washing system 10-1 and washing system 10-2, respectively.
The items, which are either accommodated directly on a conveying belt 58 or are retained by racks, run, in the conveying direction T, through an entrance tunnel 55, the following pre-wash zone 51, the main wash zone 52, the post-wash zone 53, the final rinse zone 54 and a drying zone 56 into an exit section 57.
The aforementioned treatment zones 51, 52, 53, 54 of the conveyor ware washer 50 are each assigned spray nozzles 13-1, 13-2, 13-3, 13-4, via which fluid is sprayed onto the items, which are conveyed through the respective treatment zones 51, 52, 53, 54 by the conveying belt 58. At least the pre-wash zone 51, the main wash zone 52 and the post-wash or pre-rinse zone 53 are each assigned a tank (washing tank 14-1, 14-2, 14-3), in which sprayed washing fluid is accommodated and/or washing fluid for the spray nozzles 13-1, 13-2, 13-3 of the relevant zones 51, 52, 53 is supplied.
The pre-wash zone 51, the main wash zone 52 and the post-wash zone 53 of the conveyor ware washer 50 according to the first embodiment of the invention, which is illustrated in figure 1, each have a washing system 10-1, 10-2, 10-3. Each washing system 10-1, 10-2, 10-3 is made up of a wash pump 11-1, 11-2, 11-3, of a line system 12-1, 12-2, 12-3, which is connected to the wash pump 11-1, 11-2, 11-3, and of the spray nozzles 13-1, 13-2, 13-3, which are connected to the line system 12-1, 12-2, 12-3.
Also provided is a control device 100 (illustrated only schematically in the drawings) that is connected with the machine components and programmed or otherwise configured to effect and control washing operations. In the case of the embodiment of the invention realized as a conveyor ware washer 50, the control device serves (inter alia) to activate the respective wash pumps 11-1, 11-2, 11-3 of the washing systems 10-1, 10-2, 10-3 during a washing process such that, at least at certain times, washing fluid is supplied, via the associated line system 12-1, 12-2, 12-3, to the spray nozzles 13-1, 13-2, 13-3 of the nozzle system associated with the respective washing system 10-1, 10-2, 10-3. At the same time, the control device 100 serves to activate the wash pump 11-1 and the dirt discharge pump 74-1, in a synchronized manner according to the invention, in order to improve the dirt discharge specifically in that region of the machine 50 which is in the vicinity of the entrance. This measure makes it possible to dispense with manual preliminary cleaning (pre-washing) which is usually carried out outside the machine, wherein it is ensured, in particular, that coarse soiling such as, for example, food leftovers or serviettes, which, up until now, have been removed from the items by manual preliminary cleaning, does not adversely affect the washing performance of the pre-wash zone 51.
The construction and the functioning of the washing system assigned to the at least one wash zone 51 in the case of the conveyor ware washer 50 shown in figures 1 and 2 will be described in more detail at a later stage in the text with reference to the hydraulics diagram according to figure 3.
In the case of the conveyor ware washer 50 illustrated in figure 1, final rinse fluid in the form of fresh water, which may have further chemical additives, for example rinse aid, mixed with it, is sprayed onto the items (not illustrated in figure 1) via the spray nozzles 13-4 of the final rinse zone 54, these nozzles being arranged above and below the conveying belt 58. As is illustrated in figure 1, it is also possible for laterally arranged spray nozzles 13-5 to be provided in the final rinse zone 54.
A part of the final rinse fluid sprayed in the final rinse zone 54 is conveyed from zone to zone, counter to the conveying direction T of the items, via a cascade system. The rest of the final rinse fluid is channeled directly into the pre-washing tank 14-1 of the pre-wash zone 51 via a valve 59 and a bypass line 60.
The final rinse fluid sprayed in the final rinse zone 54 is collected in the tank (post-wash or pre-rinse tank 14-3) of the post-wash or pre-rinse zone 53, from which it is delivered to the spray nozzles 13-3 (post-wash or pre-rinse nozzles) of the post-wash or pre-rinse zone 53 via the wash pump 11-3, which belongs to the washing system 10-3 of the post-wash or pre-rinse zone 53. In the post-wash or pre-rinse zone 53, washing fluid is rinsed off from the items to be washed.
The fluid which accumulates here flows into the washing tank 14-2 of the main wash zone 52, is usually provided with a detergent and is sprayed onto the items by means of a wash pump 11-2, which belongs to the washing system 10-2 of the main wash zone 52, via the spray nozzles 13-2 (wash nozzles) of the washing system 10-2, which belongs to the main wash zone 52.
From the washing tank 14-2 of the main wash zone 52, the washing fluid then flows into the pre-washing tank 14-1 of the pre-wash zone 51. The washing fluid collected in the pre-washing tank 14-1 is sprayed onto the items in the pre-wash zone 51 by means of a wash pump 11-1, which belongs to the washing system 10-1 of the pre-wash zone 51, via the spray nozzles 13-1 (pre-wash nozzles) of the washing system 10-1, which belongs to the pre-wash zone 51, in order for coarse soiling to be removed from the items.
In the case of the conveyor ware washer 50 illustrated in figure 1, the main wash zone 52 has a tank covering sieve 20-2, which is arranged above the main washing tank 14-2. During operation of the conveyor ware washer 50, washing fluid is sprayed onto the items via the spray nozzles 13-2 (wash nozzles) of the washing system 10-2. The sprayed washing fluid flows back into the washing tank 14-2 of the main wash zone 52 under gravitational forces, wherein the dirt particles rinsed off from the items in the main wash zone 52 are held back by the tank covering sieve 20-2, provided the dirt particles are larger than the mesh width of the tank covering sieve 20-2. The mesh width of the tank covering sieve 20-2 is preferably approximately 1 mm to 4 mm.
In the case of the conveyor ware washer 50 which is illustrated schematically in figure 1, cleaning of the tank covering sieve 20-2 requires operation to be interrupted, so that the tank covering sieve 20-2 can be cleaned manually.
Part of the washing fluid sprayed in the main wash zone 52 passes into the washing tank (pre-washing tank 14-1) of the pre-wash zone 51 via an overflow system 61. As is also the case with the main wash zone 52, the pre-wash zone 51 is provided with a tank covering sieve 20-1, which is realized as a planar sieve. This tank covering sieve 20-1 is arranged above the washing tank (pre-washing tank 14-1) of the pre-wash zone 51, in order for dirt particles to be separated from the washing fluid which is sprayed in the pre-wash zone 51 and flows back into the pre-washing tank 14-1 under gravitational force. The mesh width of the tank covering sieve 20-1 is preferably in a range between approximately 1 mm and 4 mm.
Since - as explained in the introduction - the concentration of dirt in the washing fluid is at its greatest in the pre-wash zone 51, since it is here that most dirt accumulates, the conveyor ware washer 50 illustrated in figure 1 is provided with a dirt collecting system 70 which is assigned to the pre-wash zone 51 and has a dirt collecting region 71-1 arranged in the pre-wash zone 51, and in particular within the pre-washing tank 14-1. The construction and the functioning of the dirt collecting system 70 which is used in the case of the conveyor ware washer 50 illustrated in figure 1 will be described in more detail hereinbelow with reference to the illustration in figure 3.
In the case of that embodiment of the conveyor ware washer 50 which is illustrated in figure 1, the dirt collecting region 71 serves to collect the dirt particles separated from the washing fluid by means of the tank covering sieve 20-1. In specific terms, and as will be described in more detail hereinbelow with reference to the hydraulics diagram in figure 3, the dirt collecting region 71-1 is realized as a chamber which is arranged in the pre-washing tank 14-1, is completely closed at its sides and is open in the upward direction, and therefore, via this opening, it is possible for the dirt particles separated by means of the tank covering sieve 20-1 to pass into the chamber-like dirt collecting region 71-1. Since the dirt collecting region 71 is completely closed at the sides it is possible to prevent effectively the situation where the dirt particles collected in the dirt collecting region 71-1 can pass back into the pre-washing tank 14-1 and contaminate the washing fluid collected in the pre-washing tank 14-1.
In specific terms, and as will be described in more detail hereinbelow with reference to the illustration in figure 3, it is preferred if the tank covering sieve 20-1 is arranged above the dirt collecting region 71-1 and has a run-off inclination in the form of a slope running in the direction of a supply opening 22, wherein the upwardly open dirt collecting region 71-1 is arranged below the supply opening 22, and therefore the dirt particles separated by means of the tank covering sieve 20-1 can pass into the dirt collecting region 71-1 by means of the supply opening 22.
It is conceivable here, in particular, for the tank covering sieve 20-1 to be realized at least in regions in the manner of a funnel, wherein the supply opening 22 is realized within the funnel-shaped region 21 of the tank covering sieve 20-1, and preferably in the center of the funnel-shaped region 21 of the tank covering sieve 20-1 (cf., in this respect, in particular also the illustration in figure 3).
The dirt collecting system 70 which is used in the case of the embodiment illustrated in figure 1 also has a dirt discharge pipe system which is connected to the dirt collecting region 71-1, comprises a vertical pipe 72-1 and a dirty-water line 73-1 and by means of which dirt particles collected in the dirt collecting region 71-1 are discharged from the pre-wash zone 51. As is illustrated, a dirt discharge pump 74-1 is arranged in the dirt discharge pipe system 72-1, 73-1. The inlet, on the intake side, of the dirt discharge pump 74-1 is connected to the lower region of the dirt collecting region 71-1 via the vertical pipe 72-1, which belongs to the dirt discharge pipe system 72-1, 73-1. The outlet, on the delivery side, of the dirt discharge pump 74-1 opens out into the dirty-water line 73-1, which belongs to the dirt discharge pipe system.
In the case of the embodiment illustrated in figure 1, the dirty-water line 73-1 leads to an external dirt collecting container 80, which is arranged outside of the pre-wash zone 51, upstream of the entrance tunnel 55 of the conveyor ware washer 50. This external dirt collecting container 80 preferably has a sieve and a connection 81 to a waste water system.
Since, when washing fluid is being sprayed in the pre-wash zone 51, it is not possible to prevent part of the sprayed washing fluid from passing into the dirt collecting region 71, the dirt discharge pump 74-1 delivers out of the pre-wash zone 51 not just the dirt particles separated by means of the tank covering sieve 20-1, but also part of the washing fluid. The material removed from the dirt collecting region 71-1 (dirt particles and washing fluid) is sieved in the dirt collecting container 80, wherein the liquid constituents (washing fluid) can be fed to a waste water system via the outflow connection 81 and the solids remaining in the dirt collecting container 80 (dirt particles) can then be disposed of. As is illustrated in figure 2, it is also conceivable, as an alternative to the embodiment illustrated in figure 1, to pump the dirt particles with the waste water out of the pre-wash zone 51 into a waste disposal system 82, wherein this system 82 can be positioned locally directly alongside the conveyor ware washer 50 or else further away. The waste disposal system 82 used may be constituted by squeezing-out systems for separating solids and liquids and/or comminuting systems (grinding, cutting systems, etc.). It is preferably likewise the case that the material removed from the dirt collecting region 71-1 (dirt particles and washing fluid) is sieved in the waste disposal system 82, wherein the liquid constituents (washing fluid) can be supplied to a waste water system via an outflow connection 83 and the solids remaining in the waste disposal system 82 (dirt particles) can then be disposed of. In the case of the embodiment of figure 2, the control device 100 likewise serves to activate the wash pump 11-1 and the dirt discharge pump 74-1, in a synchronized manner according to the invention, in order to improve the dirt discharge specifically in that region of the machine 50 which is in the vicinity of the entrance.
In the case of those exemplary embodiments of the conveyor ware washer 50 according to the invention which are illustrated in figures 1 and 2, the washing system assigned to the pre-wash zone 51 is also provided in each case with a waste water pump 40 which is connected or can be connected on the intake side to the washing tank 14-1 and is connected or can be connected on the delivery side to a waste water pipe system 41. As is also the case with the other pumps belonging to the washing system (wash pump 11-1, dirt discharge pump 74-1), the waste water pump 40 can be activated by the control device 100 in order, when necessary, for at least part of the washing fluid collected in the washing tank 14-1 to be pumped out into an on-site waste water network via the waste water pipe system 41.
According to the invention, a device 42 for determining the degree of dirt in the washing fluid is also provided. In the case of the embodiments which are illustrated by way of example in figures 1 and 2, the device 42 for determining the degree of dirt in the washing fluid has at least one turbidity sensor, which is arranged in the waste water pipe system 41, and realized, in such a manner in order to determine the degree of dirt in the washing fluid flowing through the waste water pipe system 41 when washing fluid is being pumped out of the washing tank 14-1.
The construction and the functioning of a washing system which is used, for example, in a ware washer realized as a conveyor ware washer according to figures 1 and 2 will be described hereinbelow with reference to the hydraulics diagram illustrated in figure 3. The washing system can nevertheless also be used in a ware washer realized as a box-type ware washer, as will be described with reference to the illustration in figure 4.
The dirt collecting system 70 which is illustrated schematically in figure 3 is arranged within a washing tank 14-1 of a conveyor ware washer 50. The dirt collecting system 70 has a tank covering sieve 20-1 which is arranged preferably in the washing tank 14-1, above the level of the washing fluid accommodated in the washing tank 14-1. The tank covering sieve 20-1 serves to separate dirt particles from the sprayed washing fluid which flows back into the washing tank under gravitational force. For this reason, a suitable mesh width has to be provided for the tank covering sieve 20-1.
The dirt collecting system 70 also has a dirt collecting region 71, which is realized as a completely closed chamber which is open in the upward direction. Via the opening of the dirt collecting region 71, which is realized as a chamber, the dirt particles separated by the tank covering sieve 20-1 are supplied to the dirt collecting region 71. For this purpose, it is preferred if the tank covering sieve 20-1 has a run-off inclination in the form of a slope running in the direction of a supply opening 22, wherein the upwardly open dirt collecting region 71 is arranged below the supply opening 22. As is illustrated in figure 3, it is conceivable, for example, for the tank covering sieve 20-1 to be realized at least in regions in the manner of a funnel, wherein the supply opening 22 is realized within the funnel-shaped region 21 of the tank covering sieve 20-1, and preferably in the tapered region of the funnel-shaped region 21 of the tank covering sieve 20-1.
It is also preferred if the dirt collecting region 71 is realized in a funnel-shaped manner at the upper end, in order for it to be possible for it to be inserted into the supply opening 22 of the tank covering sieve 20-1 and accommodated therein.
During operation of the ware washer, washing fluid is sprayed in the wash zone 51 assigned to the washing system, wherein part of the sprayed washing fluid flows back into the washing tank 14-1 via the tank covering sieve 20-1. The rest of the sprayed washing fluid flows directly, under gravitational force, into the dirt collecting region 71 via the supply opening 22, which is provided in the tank covering sieve 20-1.
If the ware washer is realized as a conveyor ware washer (cf. figures 1 and 2), it is the case that - as already indicated - during operation of the ware washer, washing fluid is sprayed onto the items via the spray nozzles 13-1 (pre-wash nozzles) and/or via the spray nozzles 13-2 (wash nozzles). If the ware washer, in contrast, is realized as a box-type ware washer (cf. figure 4), and therefore the items to be treated remain stationary and the individual treatment steps take place chronologically one after the other, then it is the case that, during operation of the ware washer, the washing fluid is sprayed onto the items in the wash zone via the wash nozzles designated "13" in figure 4.
The dirt particles rinsed off from the items during the washing operation - provided they are larger than the mesh width of the tank covering sieve 20-1 - are prevented by the tank covering sieve 20-1 from passing into the washing fluid collected in the washing tank 14-1. Rather, the dirt particles separated by the tank covering sieve 20-1 are moved, by the run-off inclination, to the supply opening 22 and thus pass into the dirt collecting region 71. Since the side walls of the dirt collecting region 71 are completely closed, it is no longer possible for the dirt particles collected in the dirt collecting region 71 to pass into the washing fluid which is collected in the washing tank 14-1. Even if the dirt particles collected in the dirt collecting region 71 are comminuted further as a result of washing fluid falling downward, it is still not possible for this dirt to pass into the washing fluid collected in the washing tank 14-1, and thus to increase the content of dirt in the washing fluid.
In order for it to be possible for the dirt collecting region 71 to be emptied automatically, the dirt collecting system 70 also has a dirt discharge pipe system. In the case of that embodiment of the dirt discharge system 70 which is illustrated in figure 3, said dirt discharge pipe system comprises a vertical pipe 72-1, which is connected to the lower region of the dirt collecting region 71. The vertical pipe 72-1 is connected to the inlet, on the intake side, of a dirt discharge pump 74-1. The outlet, on the delivery side, of the dirt discharge pump 74-1 opens out into a dirty-water line 73-1, and therefore, upon activation of the dirt discharge pump 74-1, the contents of the dirt collecting region 71 can be removed from the wash zone.
Also provided in the case of the hydraulics diagram illustrated in figure 3 is a waste water pump 40 which is connected or can be connected on the intake side to the washing tank 14-1 and is connected or can be connected on the delivery side to a waste water pipe system 41 for the pumping out, when necessary, of at least part of the washing fluid collected in the washing tank 14-1.
The hydraulics diagram illustrated in figure 4 shows, schematically, a washing system which is suitable, in particular, for use in the treatment chamber of a ware washer realized as a box-type ware washer. Such a ware washer has a program control device 100, for controlling at least one wash program, and a treatment chamber, which can be closed by a door (not shown) or a hood (not shown) and is intended for accommodating items to be washed (not shown), for example crockery, silverware, pots, pans and/or trays.
A washing tank 14 for accommodating sprayed fluid from the treatment chamber 4 is located below the treatment chamber 4. A wash pump 11 is provided for delivering washing fluid from the washing tank 14, through a washing-fluid-line system 5, to wash nozzles 13. The wash nozzles 13 are directed, in the treatment chamber 4, on to the region of the items to be washed, in order to spray washing fluid onto the items. The sprayed washing fluid flows back into the washing tank 14 under gravitational force. Therefore, the washing tank 14, the wash pump 11, the washing-fluid-line system 5, and the wash nozzles 13, together with the treatment chamber 4, form a washing fluid circuit.
A final rinse system contains a final rinse pump 44 for delivering final rinse fluid through a final-rinse-line system 48 to final rinse nozzles 49 which, in the treatment chamber 4, are directed on to the region of the items to be washed. The final rinse fluid sprayed by the final rinse nozzles 49 flows from the treatment chamber 4 into the washing tank 14 under gravitational force. The final-rinse-line system 48 connects the delivery side of the final rinse pump 44 to the final rinse nozzles 49.
It is possible for the wash nozzles 13 and the final rinse nozzles 49 to be arranged above and/or below, and if desired also to the side of, the item-containing region and to be directed in each case toward the item-containing region, in which the items can be positioned in the treatment chamber 4 in order to be washed.
It is preferable for a multiplicity of wash nozzles 13 to be provided on at least one upper washing arm, for a multiplicity of wash nozzles 13 to be provided on at least one lower washing arm, for a multiplicity of final rinse nozzles 49 to be provided on at least one upper final rinse arm and for a multiplicity of final rinse nozzles to be provided on at least one lower final rinse arm.
Before final rinse fluid is sprayed, in each case a quantity of washing fluid which corresponds to the quantity of final rinse fluid which is to be sprayed is pumped out of the washing tank 14 by means of a waste water pump 40, of which the intake side is connected to a sump of the washing tank 14.
If, prior to initial start up of the ware washer realized as a box-type ware washer, the washing tank 14 is empty, it has to be filled with fresh water first of all via a fresh-water line (not shown) or by means of the final rinse system, which contains the final rinse pump 44.
The final rinse fluid may be fresh water or fresh water mixed with rinse aid.
The washing fluid contains detergent, which is metered, by a detergent-metering device (not shown), into the fluid contained in the washing tank 14.
The ware washer according to the hydraulics diagram shown in figure 4 is provided in each case with a fresh water connection 46, which can be connected to a fresh water supply network. The fresh water connection 46 can be connected to the intake side of the final rinse pump 44 via a fresh water supply valve, which can be controlled by the control device 100, and via an air gap and, preferably, via a boiler 45. Rinse aid can be metered into the fresh water, for example, in the boiler 45.
The boiler 45 is provided with at least one level sensor for regulating the level of fluid in the boiler 45 by corresponding opening and closure of the fresh water valve at the fresh water connection 46 by means of the control device 100.
As is also the case with the above-described conveyor ware washers, the ware washer realized as a box-type ware washer, according to the hydraulics diagram shown in figure 4, has no external pre-cleaning station (that is to say one which is arranged outside the machine or treatment chamber 4) since, in the case of the exemplary embodiments illustrated, pre-cleaning of the items to be washed takes place within the treatment chamber 4. In particular this thus dispenses, according to the invention, with time-consuming (manual) pre-cleaning prior to the items being closed in the treatment chamber 4.
In order that the machine can carry out the pre-cleaning within the treatment chamber 4 itself, without the washing fluid becoming too contaminated in the process (which would reduce the quality of a following washing process), the washing system illustrated in figure 4 is provided with a dirt collecting system 70 and a waste water pump which is connected or can be connected on the intake side to the washing tank 14 and is connected or can be connected on the delivery side to a waste water pipe system 41 in order to pump out, when necessary, at least part of the washing fluid collected in the washing tank 14.
A device 42 for determining the degree of dirt in the washing fluid is also provided, wherein this device 42 preferably has at least one turbidity sensor, which is arranged and realized in such a manner in order to determine the degree of dirt in the washing fluid flowing through the waste water pipe system 41 when washing fluid is being pumped out of the washing tank 14.
The construction and the functioning of the washing system 70 have already been described with reference to the illustration in figure 3. To avoid repetition, reference is made to what has already been said.
The interaction of the wash pump 11 (and/or 11-1), of the dirt discharge pump 74 (and/or 74-1) and of the waste water pump 40 will be described hereinbelow with reference to the program sequences shown in figures 5a to c. In specific terms, the invention provides a control device 100 which is realized to activate, selectively, in a synchronized manner, the wash pump 11 and/or 11-1, the dirt discharge pump 74 and/or 74-1 and the waste water pump 40 in such a way that

during a pre-wash phase S1, at least part of the washing fluid collected in the washing tank 14 and/or 14-1 is supplied to the at least one wash nozzle 13 and/or 13-1 by means of the wash pump 11 and/or 11-1; and/or
during a dirt discharging phase S2, at least part of the dirt particles separated from the washing fluid by way of the dirt collecting system 70 is supplied to the dirt discharge pipe system 72, 73 and/or 72-1, 73-1 by means of the dirt discharge pump 74 and/or 74-1; and/or
during a main wash phase S3, at least part of the washing fluid collected in the washing tank 14 and/or 14-1 is supplied to the at least one wash nozzle 13 and/or 13-1 by means of the wash pump 11 and/or 11-1; and/or
during a pump-out phase S4, at least part of the washing fluid collected in the washing tank 14 and/or 14-1 is supplied to the waste water pipe system 41 by means of the waste water pump 40.

In the pre-wash phase S1, during which at least part of the washing fluid collected in the washing tank 14 and/or 14-1 is supplied to the at least one wash nozzle 13 and/or 13-1 by means of the wash pump 11 and/or 11-1, in order for the wash fluid to be sprayed onto the items to be washed, coarse soiling such as, for example, food leftovers are rinsed off from the items, this soiling being removed from the items in conventional machines during the manual pre-washing.
In the case of the program sequence which is shown schematically in figure 5a, the pre-wash phase S1 is followed by a dirt discharging phase S2. In the case of this dirt discharging phase S2, at least some of the dirt particles separated from the washing fluid by way of the dirt collecting system 70 are supplied to the dirt discharge pipe system 72, 73 and/or 72-1, 73-1 by means of the dirt discharge pump 74 and/or 74-1. This therefore constitutes a (first) pump-out phase, which is carried out by the dirt discharge pump 74 and/or 74-1. In this case, at least many of the dirt particles separated from the washing fluid by way of the dirt collecting system 70 are pumped preferably into a dirt container provided externally or internally (in relation to the ware washer).
In the case of the program sequence which is shown schematically in figure 5a, the dirt discharging phase S2 does not take place immediately following completion of the pre-wash phase S1. Rather, there is a pause lasting preferably approximately 1 to 2 seconds, during which neither the wash pump 11 and/or 11-1 nor the dirt discharge pump 74 and/or 74-1 is activated, between the end of the pre-wash phase S1 and the start of the dirt discharging phase S2. This pause provides for better concentration of dirt in the dirt collecting region 71 of the dirt collecting system 70. Since the operation of both the wash pump 11 and/or 11-1 and of the dirt discharge pump 74 and/or 74-1 is stopped for a brief period of time, it is ensured that the dirt particles which are to be discharged in the dirt discharging phase S2 collect in a particularly effective manner in the dirt collecting region 71 of the dirt collecting system 70.
In the case of the program sequence which is illustrated schematically in figure 5a, the dirt discharging phase S2, which lasts for example approximately 2 to 3 seconds, is followed by the main wash phase S3, during which at least part of the washing fluid collected in the washing tank 14 and/or 14-1 is applied to the at least one wash nozzle 13 and/or 13-1 by means of the wash pump 11 and/or 11-1, in order for this washing fluid to be sprayed onto the items to be washed. Soiling left on the items is removed therefrom in this way. Depending on the degree of dirt and/or treatment program selected, the main wash phase usually lasts 20 to 45 seconds.
In the case of the program sequence which is illustrated schematically in figure 5a, completion of the main wash phase S3 is followed by a further (second) pump-out phase S4, during which at least part of the washing fluid collected in the washing tank 14 and/or 14-1 is supplied to the waste water pipe system 41 by means of the waste water pump 40.
This is followed, in particular in the case of the ware washer realized as a box-type ware washer, by a final rinse phase S5, in the case of which, by means of a final rinse system, final rinse fluid, in particular fresh water with rinse aid possibly metered into it, subjects the already washed items to final rinsing, i.e. the washing fluid still adhering to the items is rinsed off. Spraying final rinse fluid during the final rinse phase S5 serves, at the same time, to regenerate the washing fluid collected in the washing tank 14 and/or 14-1.
In the case of the program sequence which is illustrated schematically in figure 5a, a measuring phase S6 takes place in parallel with, or immediately after the final rinse phase S5, for the purpose of determining the degree of dirt in the washing fluid pumped out in the pump-out phase S4 and located in the waste water pipe system 41. This can be done, for example, by way of a turbidity measurement. During the measuring phase S6, therefore, the quality of the washing fluid is checked. If the quality falls below a previously fixed or fixable limit value, i.e. if the washing fluid tested in the measuring phase S6 has a certain (previously fixed or fixable) degree of turbidity, the quantity of final rinse fluid sprayed during the final rinse phase S5 is correspondingly increased automatically in order to regenerate (dilute) the washing fluid sufficiently for the washing fluid then to have the predetermined quality again. It is conceivable here for the duration of the final rinse phase S5 to be selected in dependence on the washing fluid quality determined during the measuring phase S6.
For the individual phases, in the case of the program sequence shown in figure 5a, the following durations are conceivable:

duration t1 of the pre-wash phase S1: 4 to 12 seconds, preferably 6 to 10 seconds, even more preferably 8 seconds;
duration t2 of the pause between the pre-wash phase S1 and the dirt discharging phase S2: 1 to 3 seconds, preferably 1 to 2 seconds;
duration t3 of the dirt discharging phase S2: 1 to 8 seconds, preferably 2 to 5 seconds;
duration t4 of the main wash phase S3: 10 to 90 seconds, preferably 20 to 50 seconds, or as an alternative 40 to 50 seconds, preferably 42 to 48 seconds;
duration t5 of the pump-out phase S4: 2 to 10 seconds, preferably 3 to 6 seconds;
duration t6 of the final rinse phase S5 (depending on the degree of dirt in the washing fluid): 4 to 10 seconds, preferably 5 to 8 seconds, even more preferably 7 seconds.

The values indicated above should be considered merely as examples rather than having any limiting effect. In particular the same or similar values are possible for the program sequences illustrated in figure 5b and figure 5c.
Figure 5b illustrates, schematically, a further example of a program sequence for a ware washer according to the present invention. In contrast to the program sequence which is described with reference to the illustration in figure 5a, the program sequence shown in figure 5b has no pause between the pre-wash phase S1 and the dirt discharging phase S2. Rather, in the case of the exemplary embodiment according to the program sequence illustrated in figure 5b, the dirt discharge pump 74 and/or 74-1 is still activated during the pre-wash phase S1 and initiates the dirt discharging phase S2. Since there is no pause between the pre-wash phase S1 and the dirt discharging phase S2, and the pre-wash phase S1 and the dirt discharging phase S2 overlap in time, the overall duration of the washing cycle can be shortened correspondingly.
Figure 5c illustrates, schematically, a further example of a program sequence for a ware washer according to the present invention. Specifically, figure 5c shows two successive cycles. In the case of the first cycle, which is indicated by "①" in figure 5c, first of all a pre-wash phase S1 and then a dirt discharging phase S2 and main-wash phase S3 take place - as is also the case with the program sequence shown in figure 5a - wherein there is once again a pause between the pre-wash phase S1 and the dirt discharging phase S2.
In the case of the alternative illustrated in figure 5c, in contrast to the program sequence shown in figure 5a, in the first cycle ① the main wash phase S3 is followed immediately by the final rinse phase S5, rather than by a pump-out phase S4.
In a following, second cycle, which is indicated by "②" in figure 5c, a pre-wash phase S1 takes place, as do a main wash phase S3 and a pump-out phase S4, but no dirt discharge phase S2 after the pre-wash phase S1.
In the case of the second cycle ② of the program sequence which is illustrated schematically in figure 5c, the measuring phase S6, during which the degree of dirt in the washing fluid pumped out during the pump-out phase S4 and located in the waste water pipe system 41 is determined, takes place parallel with, or immediately after, the final rinse phase S5. The quantity of final rinse fluid sprayed during the final rinse phase S5 here depends on the washing fluid quality determined during the measuring phase S6.
In the case of the embodiments of the ware washer according to the invention, the control device 100 is designed to activate, selectively, in a synchronized manner, the wash pump 11 (and/or 11-1), the dirt discharge pump 74 (and/or 74-1) and the waste water pump 40, and therefore it is possible to realize the program sequences described above with reference to the illustrations in figures 5a to 5c. It is, in particular, conceivable here for the recirculating circuit of the washing system to be interrupted for a certain period of time t2 once the pre-wash phase S1 has been carried out, and for the dirt particles to be discharged once the pre-wash phase S1 has been carried out or, at the latest, after this period of time t2 has elapsed. For this purpose, the control device 100 is connected to the pumps 11, 74 via control lines 100-1, 100-2. If wash pump recirculation is interrupted for a short period of time, the washing fluid can vortex on the sieve. The kinetic energy of the dirt particles contained therein decreases as a result, and therefore they can be sucked more easily into the dirt collecting region 71 by means of the dirt discharge pump 74. The control device 100 here may be realized as part of a machine control means or integrated therewith.
The control device 100 preferably has a microprocessor with a program code which can be run thereon and triggers the timed activation of the pumps 11, 74. The intention here is for the control device 100 to be realized preferably for cyclically repeating the synchronized activation of the wash pump 11 and of the dirt discharge pump 74, in order to ensure a regular discharge of dirt particles.
In addition, the dirt discharge pump 74 may be designed in order that, continuously or at predetermined times and/or in the case of predetermined events, the dirt particles collected in the dirt collecting region 71 are removed together with the washing fluid likewise collected in the dirt collecting region 71. In particular, it is conceivable here for the dirt discharge pump 74 to be activated, via the already mentioned control means 100, in dependence on the quantity of dirt particles collected in the dirt collecting region 71.
Nevertheless, it is, of course, conceivable, for dirt to be pumped out of the dirt collecting region 71 in dependence on, for example, the level in the dirt collecting region 71, the level in the washing tank 14, or other factors.
If the dirt collecting system 70 is used in a conveyor ware washer 50 (cf., for example, figures 1 to 4), it is also conceivable for the dirt discharge pump 74 to be activated, for example, in dependence on the conveying speed at which the items to be washed are conveyed through the treatment zones of the conveyor ware washer 50 or, for example, in dependence on the quantity of final rinse fluid which is sprayed per unit of time in the final rinse zone 54.
It is, of course, possible for dirt to be discharged not just at the start of each washing cycle S3, but also at the end thereof or in the middle. The essential factor is for the discharging operation to be cyclically repeated, in order for a uniformly high washing quality to be achieved.
A further washing system, which - as is also the case with the washing system which is illustrated schematically in figure 4 - is suitable, in particular, for use in the treatment chamber of a ware washer realized as a box-type ware washer, will be described hereinbelow with reference to the hydraulics diagram illustrated in figure 6.
The washing system according to figure 6 differs from the washing system described above with reference to the illustration in figure 4, in particular, in that the control device 100 is realized to activate the dirt discharge pump 74 in dependence on the amount of dirt particles separated from the washing fluid by way of the dirt collecting system 70. Specifically, the washing system which is illustrated schematically in figure 6 uses a device 99 which serves to detect the fill level in the washing tank 14. This device 99 is connected to the control device 100, wherein the control device 100 is realized to activate the dirt discharge pump 74 automatically and preferably selectively automatically in dependence on the detected fill level. The washing fluid level in the washing tank 14 during pre-washing serves here as an indicator of the quantity of dirt introduced into the washing system. Use is made here of the finding that the backflow of washing fluid into the washing tank 14 decreases as the introduction of dirt during pre-washing increases, since, in the case of a high level of dirt being introduced, the sieve surface of the dirt collecting system 70 (i.e. the tank covering sieve 20) becomes blocked, at least in part, and thus prevents, at least in part, the backflow of the washing fluid into the washing tank 14.
In order for it to be possible for the dirt discharge pump 74 to be activated preferably automatically in accordance with the quantity of dirt introduced, the fill level in the washing tank 14 is detected in the case of the embodiment illustrated in figure 6, wherein the dirt discharge pump 74 is activated, by means of the control device 100, in dependence on the detected fill level.
It is conceivable here for the control device 100 to be realized to activate the dirt discharge pump 74 for a certain duration, wherein this certain duration has been previously fixed and depends on the detected fill level (and thus on the quantity of dirt introduced into the washing system).
In order for the dirt discharge pump 74 to be activated as precisely as possible, it is conceivable for the control device 100 to have a comparator in order for the fill level value detected by means of the device 99 to be compared with at least one previously fixed or fixable threshold value. It is conceivable here for the control device 100 to activate the dirt discharge pump 74 for a previously fixed duration, wherein this previously fixed duration depends on the result of the comparison carried out by means of the comparator.
In the case of the washing system illustrated schematically in figure 6, the control device 100 is also realized to activate the dirt discharge pump 74 selectively until a previously fixed volume of washing fluid is pumped out by means of the dirt discharge pump 74. This previously fixed volume of washing fluid is dependent on the fill level detected by means of the device 99. For this purpose, it is provided that the dirt discharge pump 74 is assigned a device 98 by means of which the volume of washing fluid, or washing fluid with dirt particles, discharged from the washing system by the dirt discharge pump 74 is determined.
The device 99 for detecting the fill level in the washing tank 14 is preferably a fill level sensor which is arranged in the washing tank 14 and is designed to detect the fill level in the washing tank 14 continuously or at predetermined or predeterminable times or in the case of predetermined or predeterminable events. It is recommended here, for example, to provide a pressure sensor which is arranged in the washing tank 14 and designed to detect the hydrostatic pressure in the washing fluid accommodated in the washing tank 14 at the level of the pressure sensor. The control device 100 should be realized here to determine the current fill level in the washing tank 14 by way of the detected hydrostatic pressure. It is, of course, also the case, however, that other embodiments are possible for detecting and determining the fill level of the washing fluid in the washing tank 14.
In a preferred realization of the washing system which is illustrated schematically in figure 6, it is provided that the device 99 used for detecting the fill level in the washing tank 14 is constituted by a total of two fill level limit switches which are arranged in the washing tank 14 and designed such that these fill level limit switches can determine whether the fill level in the washing tank 14 falls below a first (upper) fill level threshold value, and whether the fill level in the washing tank 14 likewise falls below, in addition, a second (lower) fill level. It is conceivable here, for example, for the control device 100 to activate the dirt discharge pump 74 for a first previously fixed or fixable duration when the two fill level limit switches detect that only the first (upper) fill level threshold value is not met. On the other hand, the control device 100 should activate the dirt discharge pump 74 for a second previously fixed or fixable duration when the two fill level threshold values detect that the second (lower) fill level threshold value is also not met.
As an alternative to this, it is conceivable for the control device 100 to be realized to activate the dirt discharge pump 74 until a previously fixed volume of washing fluid is pumped out by means of the dirt discharge pump 74 when the two fill level limit switches detect that only the first (upper) fill level threshold value is not met, whereas the control device 100 activates the dirt discharge pump 74 until a previously fixed second volume of washing fluid is pumped out by means of the dirt discharge pump 74 when the two fill level limit switches detect that the second (lower) fill level threshold value is also not met.
In a conceivable realization of the washing system which is illustrated schematically in figure 6, it is provided that, for example, 0.2 to 0.4 liters of washing fluid are discharged from the dirt collecting system 70 by means of the dirt discharge pump 74 if, during pre-washing, the minimum washing fluid level in the washing tank 14 remains below the level 01 depicted in figure 6. If the minimum washing fluid level drops to a value between the level 01 and the level 02, likewise depicted in figure 6, for example 1.2 to 2.0 liters of washing fluid are discharged by means of the dirt discharge pump 74. If the minimum washing fluid level falls below the level 02, pre-washing is interrupted, on account of the degree of dirt being too high, and then 2.5 to 3.5 liters of washing fluid are discharged. The quantities of washing fluid discharged in each case should be selected such that they are sufficient to wash out the entire sieve and dirt collecting system.
The invention is not restricted to the embodiments described in conjunction with the drawings.
It is thus conceivable, for example, for the tank covering sieve 20, 20-1 of the dirt collecting system 70 not to have an essentially centrally arranged supply opening 22, via which the dirt particles separated by means of the tank covering sieve 20, 20-1 pass into the dirt collecting region 71, 71-1. Rather, it is also possible for this supply opening 22 to be realized as a gap which is provided on a peripheral region of the tank covering sieve 20, 20-1.
It is also conceivable, in principle, for the supply opening 22 to be covered over by means of a coarse sieve, wherein this coarse sieve should preferably have a mesh width which is greater than the mesh width of the tank covering sieve 20, 20-1. Providing a coarse sieve of this type makes it possible to prevent effectively the situation where, for example, items of silverware or other utensils, other than dirty-water particles, pass accidentally into the dirt collecting region 71, 71-1.

Claims

Ware washer, in particular an industrial ware washer for crockery or utensils, which is realized as an automatic programmable machine or as a conveyor ware washer (50), wherein the ware washer has at least one washing system realized as a recirculating circuit, wherein the at least one washing system has a nozzle system with at least one wash nozzle (13; 13-1) for spraying washing fluid onto the items to be washed, a washing tank (14; 14-1) for collecting at least part of the sprayed washing fluid and a wash pump (11; 11-1) for supplying washing fluid collected in the washing tank (14; 14-1) to the at least one wash nozzle (13; 13-1), wherein there is provided a dirt collecting system (70) which is associated with the at least one washing system and is realized in order to separate dirt particles from the sprayed washing fluid which flows back into the washing tank (14; 14-1) by means of gravity, and wherein there is provided a dirt discharge pump (74; 74-1) which is connected or can be connected on the intake side to the dirt collecting system (70) and is connected or can be connected on the delivery side to a dirt discharge pipe system (72, 73; 72-1, 73-1) for the discharge, when necessary, of at least part of the washing fluid that has passed into the dirt collecting system (70) and at least part of the dirt particles separated from the washing fluid collected in the washing tank (14; 14-1) by way of the dirt collecting system (70),
characterized in that the ware washer also has a separate waste water pump (40) which is connected or can be connected on the intake side to the washing tank (14; 14-1) and is connected or can be connected on the delivery side to a waste water pipe system (41) for the pumping out, when necessary, of at least part of the washing fluid collected in the washing tank (14; 14-1), said waste water pump may be activated in coordination with the dirt discharge pump.
Ware washer according to Claim 1, wherein the dirt collecting system (70) has a tank covering sieve (20; 20-1) and a dirt collecting region (71) for collecting the dirt particles separated from the washing fluid by means of the tank covering sieve (20; 20-1), wherein the dirt collecting region (71) is open upwards but is completely closed at the sides, and wherein the dirt discharge pipe system (72, 73; 72-1, 73-1) is connected or can be connected to the dirt collecting region (71),
wherein the tank covering sieve (20; 20-1) is arranged above the dirt collecting region (71) and has a run-off inclination in the direction of a supply opening (22), wherein the upwardly open dirt collecting region (71) is arranged below the supply opening (22) in such a manner that the dirt particles separated by means of the tank covering sieve (20; 20-1) pass into the dirt collecting region (71) by means of the supply opening (22),
wherein the covering sieve (20; 20-1) is realized at least in regions in the manner of a funnel, and wherein the supply opening (22) is realized within the funnel-shaped region (21) of the tank covering sieve (20; 20-1), and preferably in the tapered region of the funnel-shaped region (21) of the tank covering sieve (20; 20-1).
Ware washer according to Claim2, wherein the supply opening (22) is realized in a central position of the tank covering sieve (20; 20-1),
wherein there is also provided a coarse sieve which covers the supply opening (22) at least in part and has a mesh width which is greater than the mesh width of the tank covering sieve (20; 20-1).
Ware washer according to one of Claims 1 to 3, wherein the waste water pipe system (41) is connected or can be connected to a waste water network on the building side and the dirt discharge pipe system (72, 73; 72-1, 73-1) is connected or can be connected to a dirt collecting container (80) which is realized externally of the washing system or with a waste disposal system (82) which is realized externally of the ware washer, and/or
wherein a device (42) for determining the degree of dirt in the washing fluid is also provided.
wherein the device (42) for determining the degree of dirt in the washing fluid has at least one turbidity sensor, which is arranged and realized in such a manner in order to determine the degree of dirt in the washing fluid flowing through the waste water pipe system (41) when the washing fluid is being pumped out of the washing tank (14; 14-1).
Ware washers according to one of Claims 1 to 4, wherein there is also provided a control device (100) which is realized to activate, selectively, in a synchronized manner, the wash pump (11; 11-1), the dirt discharge pump (74; 74-1) and the waste water pump (40) in such a way that
- during a pre-wash phase, at least part of the washing fluid collected in the washing tank (14; 14-1) is supplied to the at least one wash nozzle (13, 13-1) by means of the wash pump (11; 11-1);

- during a dirt discharging phase, at least part of the dirt particles separated from the washing fluid by way of the dirt collecting system (70) is supplied to the dirt discharge pipe system (72, 73; 72-1, 73-1) by means of the dirt discharge pump (74; 74-1);

- during a main wash phase, at least part of the washing fluid collected in the washing tank (14; 14-1) is supplied to the at least one wash nozzle (13; 13-1) by means of the wash pump (11; 11-1); and

- during a pump-out phase, at least part of the washing fluid collected in the washing tank (14; 14-1) is supplied to the waste water pipe system (41) by means of the waste water pump (40).
Ware washer according to Claim 5, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) during the pre-wash phase or after completion of the pre-wash phase, and preferably in a time-delayed manner after completion of the pre-wash phase, but prior to the start of the main wash phase, and/or
wherein the control device (100) is realized to activate the waste water pump (40) after completion of the main wash phase, and/or
wherein the control device (100) is realized to activate the waste water pump (40) in dependence on the degree of dirt in the washing fluid,
wherein the length of the pump-out phase, during which the waste water pump (40) is activated by the control device (100), depends on the degree of dirt in the washing fluid.
Ware washer according to one of Claims 5 or 6, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) in dependence on the amount of dirt particles separated from the washing fluid by way of the dirt collecting system (70),
wherein there is also provided a device (99) for detecting the fill level in the washing tank (14; 14-1), wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) automatically and preferably selectively automatically in dependence on the detected fill level,
wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) for a previously fixed duration, wherein the previously fixed duration depends on the detected fill level, and/or
wherein the control device (100) has a comparator for comparing the detected fill level with at least one previously fixed or fixable threshold value, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) for a previously fixed duration dependent on the result of the comparison carried out by means of the comparator.
Ware washer according to Claim 7, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) until a previously fixed volume of washing fluid is pumped out by means of the dirt discharge pump (74; 74-1), wherein the previously fixed volume of washing fluid is dependent on the detected fill level,
wherein the control device (100) has a comparator for comparing the detected fill level with at least one previously fixed or fixable threshold value, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) until a previously fixed volume of washing fluid, which is dependent on the result of the comparison carried out by way of the comparator, is pumped out.
Ware washer according to one of Claims 1 to 8, in particular Claim 7 or 8, wherein there is also provided a device (98), which is associated with the dirt discharge pump (74; 74-1), for determining a volume of washing fluid discharged by the dirt discharge pump (74; 74-1).
Ware washer according to one of Claims 7 to 9, wherein the device (99) for detecting the fill level in the washing tank (14; 14-1) has at least one fill level sensor which is arranged in the washing tank (14; 14-1) for continuously detecting the fill level, and/or
wherein the device (99) for detecting the fill level in the washing tank (14; 14-1) has a pressure sensor arranged in the washing tank (14; 14-1) for detecting hydrostatic pressure in the washing fluid accommodated in the washing tank (14; 14-1) at the level of the pressure sensor, and wherein the control device (100) is realized to determine the current fill level in the washing tank (14; 14-1) by way of the detected hydrostatic pressure, and/or
wherein the device (99) to detect the fill level in the washing tank (14; 14-1) has at least one fill level limit switch arranged in the washing tank (14; 14-1) for detecting whether the fill level in the washing tank (14; 14-1) falls below a previously fixed fill level threshold value,
wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) automatically and preferably selectively automatically when the previously fixed fill level threshold value is not met.
Ware washer according to Claim 10, wherein there are provided at least two fill level limit switches arranged in the washing tank (14; 14-1) for detecting whether the fill level falls below a first and/or second previously fixed fill level threshold value, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) for a first previously fixed or fixable duration when it is detected that only the first fill level threshold value is not met, and it is realized to activate the dirt discharge pump (74; 74-1) for a second previously fixed or fixable duration when it is detected that the second fill level threshold value is also not met, and/or
wherein there are provided at least two fill level limit switches arranged in the washing tank (14; 14-1) for detecting whether the fill level falls below a first and/or second previously fixed fill level threshold value, wherein the control device (100) is realized to activate the dirt discharge pump (74; 74-1) until a previously fixed first volume of washing fluid is pumped out by means of the dirt discharge pump (74; 74-1) when it is detected that only the first fill level threshold value is not met, and it is realized to activate the dirt discharge pump (74; 74-1) until a previously fixed second volume of washing fluid is pumped out by means of the dirt discharge pump (74; 74-1) when it is detected that the second fill level threshold value is also not met.
Ware washer according to one of Claims 1 to 11, wherein the ware washer is realized as a conveyor ware washer (50), wherein the conveyor ware washer (50) has at least one washing zone (51, 52) and at least one rinsing zone (54) as well as a conveying device (58) for conveying the items to be washed through the at least one washing zone (51, 52) and the rinsing zone (54) connected downstream of the at least one washing zone (51, 52) in the conveying direction (T) of the items to be washed, wherein the washing system is associated with the at least one washing zone (51, 52), or
wherein the ware washer is realized as an automatic programmable machine and has a treatment chamber, wherein the washing system is associated with the treatment chamber,wherein there is also provided a rinsing system with at least one rinse pump (44) and a rinse nozzle system (49) arranged in the treatment chamber in order to spray rinsing fluid, in particular fresh water, in the treatment chamber during a rinse phase,
wherein the amount of rinsing fluid sprayed is controlled in dependence on the degree of dirt in the washing fluid,
wherein the amount of rinsing fluid sprayed in the treatment chamber during the rinse phase is dependent on the amount of washing fluid removed from the washing tank (14; 14-1) by means of the waste water pump (40) during a pump-out phase.
Method for operating a ware washer according to one of Claims 1 to 12, wherein the method has the following method steps:
i) during a pre-wash phase, the wash pump (11; 11-1) is activated in such a manner that at least part of the washing fluid collected in the washing tank (14; 14-1) is supplied to the at least one wash nozzle (13; 13-1) for the pre-washing of the items to be washed;

ii) during a dirt discharging phase, the dirt discharge pump (74; 74-1) is activated in such a manner that at least part of the washing fluid that has passed into the dirt collecting system (70) and at least part of the dirt particles separated from the washing fluid collected in the washing tank (14; 14-1) by way of the dirt collecting system (70) is supplied to the dirt discharge pipe system (72, 73; 72-1, 73-1) for discharging dirt particles out of the treatment zone or treatment chamber of the ware washer;

iii) during a main wash phase, the wash pump (11; 11-1) is activated in such a manner that at least part of the washing fluid collected in the washing tank (14; 14-1) is supplied to the at least one wash nozzle (13; 13-1) for the main washing of the items to be washed; and

iv) during a pump-out phase, the waste water pump (40) is activated in such a manner that at least part of the washing fluid collected in the washing tank (14; 14-1) is supplied to the waste water system (41).
Method according to Claim 13, wherein the method step ii) is carried out after completion of the method step i), and preferably in a time-delayed manner after completion of the method step i), but prior to the start of the method step iii), and/or
wherein the method step iv) is carried out after completion of the method step iii), and/or
wherein the degree of dirt in the washing fluid is determined in the washing fluid supplied to the waste water pipe system (41) in the method step iv), wherein the method also has the following method step after the method step iv):
v) during a rinse phase, rinsing fluid is supplied to a rinse nozzle system (49) by way of at least one rinse pump (44) for rinsing the items to be washed.
Method according to one of Claims 13 or 14, wherein the fill level in the washing tank (14; 14-1), is detected and in the method step ii), the dirt discharge pump (74; 74-1) is activated automatically and preferably selectively automatically in dependence on the detected fill level,
wherein in the method step ii), the dirt discharge pump (74; 74-1) is activated for a previously fixed duration, wherein the previously fixed duration is dependent on the detected fill level,
wherein the detected fill level is compared to at least one previously fixed or fixable threshold value, and wherein in the method step ii), the dirt discharge pump (74; 74-1) is activated for a previously fixed duration in dependence on the result of the comparison, or
wherein the volume of washing fluid which is discharged by way of the dirt discharge pump (74; 74-1) during the dirt discharging phase in the method step ii) is determined, and wherein in the method step ii), the dirt discharge pump (74; 74-1) is activated until a previously fixed volume of washing fluid is pumped out by means of the dirt discharge pump (74; 74-1), wherein the previously fixed volume of washing fluid is dependent on the detected fill level.