The invention relates in particular to a commercial ware washer for washing dishes or utensils which is configured as a box-type ware washer or as a conveyer ware washer.

The invention is consequently directed at a ware washer which comprises at least one wash zone configured as a recirculation circuit. The wash zone configured as a recirculation circuit comprises a nozzle system having at least one wash nozzle for spraying wash liquid onto the wash ware to be washed, a wash tank for catching at least part of the sprayed wash liquid and a wash pump for feeding wash liquid collected in the wash tank to the at least one wash nozzle. In addition, the ware washer comprises a dirt catching system which is associated with the at least one wash zone and which has at least one tank cover filter for separating dirt particles from the sprayed wash liquid which flows back into the wash tank as a result of gravity.

The document DE 10 2009 048 810 A1 relates to the dishwasher that has a wash system with a nozzle system with at least one wash nozzle for spraying wash liquid, a wash tank, and a wash pump by means of which wash liquid collected in the wash tank is feed to the at least one wash nozzle. A dirt-collecting system has at least one tank-covering screen to separate off particles of dirt from the wash liquid. The dirt-collecting system also has a dirt-collecting region arranged in the wash system and is intended for collecting the particles of dirt which have been separated off from the wash liquid with the aid of the tank-covering screen, wherein the dirt-colleting region is open at the top, but closed all the way around the sides, and wherein there is also a dirt-discharging pipe system by means of which the particles of dirt collected in the dirt collecting region are discharged from the wash system.

The document WO 2013/059141 A2 relates to a ware washer that has at least one washing system with a recirculating circuit with at least one wash nozzle, one washing tank, and one wash pump. A dirt collecting system is associated with the washing system and the dirt discharge pump is connected to a dirt discharge pipe system in order to discharge at least part of the dirt particles separated from the washing fluid out of the washing system. A wastewater pump is connected or can be connected on the intake side of the washing tank and is connected or can be connected on the delivery side to a wash water pipe system for the pumping out, where necessary, of at least part of the washing fluid collected in the washing tank.

The document DE 10 2010 063 711 A1 relates to a dishwasher comprising at least one washing system embodied as a circulation circuit. The at least one washing system has a nozzle system with at least one washing nozzle for spraying washing liquid onto the items to be washed, a washing tank for collecting at least a part of the sprayed washing liquid and a washing pump for supplying washing liquid collected in the washing tank to the at least one washing nozzle. A dirt collecting system associated with the at least one wash system is further provided for collecting dirt particles from the sprayed and gravity sprayed into the wash tank, and a dirty water pump connected to the dirty collecting system for discharging the dirt particles from the dirty collection system. A control device is provided, which is designed to control the washing pump and the dirty water pump in a manner matched to one another so that the recirculation circuit of the washing system can be interrupted for a first time period, and the discharge of the dirt particles takes place within this first time period.

The document DE 10 2005 008 987 B3 relates to a multi-tank dishwasher with at least one washing zone for acting upon a wash batch with washing water in a washing chamber and comprising at least one washing water storage tank, at least one filter housing and a backwash device.

Box-type ware washers are manually loadable and unloadable ware washers. The box-type ware washers (or else referred to as "batch dish washers") may be rack-type push-through ware washers for washing dishes, also referred to as hood-type ware washers, or front loaders ("front loader ware washers"). Front loaders may be under-counter machines, counter-top machines or free-standing ware washers with front loading ("free standing front loaders").

A ware washer configured as a box-type ware washer normally comprises a treatment chamber for the washing of wash ware. Generally, there is arranged below the treatment chamber a wash tank in which liquid can flow back from the treatment chamber as a result of gravity. Situated in the wash tank is wash liquid, which is normally water, to which, if appropriate, cleaning agent can be supplied.

A ware washer configured as a box-type ware washer furthermore comprises a wash system having a wash pump, having a line system which is connected to the wash pump, and having a nozzle system which has at least one wash nozzle. The wash liquid situated in the wash tank can be delivered via the line system to the at least one wash nozzle by the wash pump and sprayed through said at least one wash nozzle in the treatment chamber onto the wash ware to be washed. The sprayed wash liquid then flows back into the wash tank as a result of gravity.

Conveyer ware washers are in particular flight-type ware washers or rack conveyer ware washers. Conveyer ware washers are normally used in the commercial sector. By contrast to box-type ware washers, in which the wash ware to be washed remains positionally fixed in the machine during washing, in conveyer ware washers, the wash ware is conveyed through different treatment zones of the conveyer ware washer.

A conveyer ware washer normally comprises at least one pre-wash zone and at least one main wash zone, which, as seen in the conveying direction of the wash ware, is arranged downstream of the pre-wash zone(s). As seen in the conveying direction, downstream of the main wash zone(s) there are generally arranged at least one post-wash zone or pre-rinse zone and at least one final rinse zone, connected downstream of the post-wash zone(s). As seen in the conveying direction, either the wash ware received directly on the conveyer belt or the wash ware held by racks normally runs, in the conveying direction, through an entry 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.

Said wash zones of the conveyer ware washer each have associated therewith a wash system, comprising a wash pump and a line system (wash line system) which is connected to the wash pump and via which wash liquid is fed to the nozzle system or to the at least one wash nozzle of the nozzle system. The wash liquid fed to the at least one wash nozzle of the nozzle system is sprayed in the respective wash zones of the conveyer ware washer onto the wash ware which is being conveyed by a conveying device of the conveyer ware washer through the respective wash zones. Each wash zone has associated therewith a tank in which the liquid sprayed by the wash nozzles is received and/or in which liquid for the nozzle systems of the respective treatment zones is provided.

In the conveyer ware washers conventionally known from the prior art, final rinse liquid in the form of fresh water, which may be pure or mixed with further additives, such as for example rinse aid, is sprayed via the spray nozzles of the final rinse zone onto the wash ware. At least part of the sprayed final rinse liquid is conveyed via a cascade system from zone to zone in the direction opposite the conveying direction of the wash ware.

The sprayed final rinse liquid is caught in a tank (post-wash tank) of the post-wash zone, from which it is delivered via the wash pump of the wash system belonging to the post-wash zone to the spray nozzles (post-wash nozzles) of the post-wash zone. Wash liquid is rinsed off the wash ware in the post-wash zone. The liquid occurring here flows into the wash tank of the at least one main wash zone, which at least one main wash zone, as seen in the conveying direction of the wash ware, is connected upstream of the post-wash zone. Here, the liquid is normally provided with a cleaning agent and, by way of a pump system (wash pump) belonging to the wash system of the main wash zone, is sprayed via the nozzles (wash nozzles) of the main wash zone onto the wash ware. From the wash tank of the main wash zone, the wash liquid - if no further main wash zone is provided - subsequently flows into the pre-wash tank of the pre-wash zone. The liquid in the pre-wash tank is, via a pump system (pre-wash pump) belonging to the wash system of the pre-wash zone, sprayed via the pre-wash nozzles of the pre-wash zone onto the wash ware, in order to remove coarse impurities from the wash ware.

Ware washers are conventionally equipped with wash pumps, which feed to the line system of the final rinse zone the final rinse liquid to be sprayed. This ensures, in particular, a virtually constant volume flow of the final rinse liquid 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 conduct the final rinse liquid to the line system of the final rinse zone. In this last-mentioned case, an actuable valve may be provided between the line system and the spray nozzles of the final rinse zone, in order to be able to achieve an intermittent or complete interruption to the supply of final rinse liquid to the spray nozzles.

Irrespective of whether a ware washer is configured as a box-type ware washer or as a conveyer ware washer, commercial ware washers for washing dishes consequently normally comprise at least one wash zone which is configured as a recirculation circuit and which comprises a nozzle system having at least one wash nozzle for spraying wash liquid onto the wash ware to be washed, a wash tank for catching at least part of the sprayed wash liquid and a wash pump for feeding liquid collected in the wash tank to the at least one wash nozzle.

Since a wash zone configured as a recirculation circuit is used for washing the wash ware, at least part of the wash liquid already sprayed in the wash zone is guided in a circuit, and so there is the risk that, owing to the permanent circulation of the wash liquid, the dirt particles removed from the wash ware are subjected to repeated comminution and thus can longer be readily separated from the wash liquid by filter devices, etc. Accordingly, for a wash zone configured as a recirculation circuit, there is the risk of the contamination with dirt of the wash liquid in the wash zone increasing as the washing time increases, with the result that there is a greater risk of wash ware being recontaminated and the washing result worsens overall.

This problem occurs in particular in the case of the pre-wash or main wash zones of a ware washer configured as a conveyer ware washer. Since, in conveyer ware washers, the washing liquid used flows in cascade form in the direction opposite the conveying direction of the wash ware to be washed, the concentration of dirt in the wash liquid is greatest in the at least one pre-wash zone compared to the concentration of dirt in the wash liquid in the remaining treatment zones, since the pre-wash zone is where the most dirt occurs.

On the other hand, it is unavoidable that, during the operation of a ware washer configured as a conveyer ware washer, part of the more heavily contaminated wash liquid in the pre-wash zone is "entrained" into the at least one main wash zone, which is connected downstream of the pre-wash zone, through the conveyance of the washware. This increases the contamination with dirt of the wash liquid in the main wash zone, and therefore the washing result in the main wash zone can also worsen.

In order for the dirt particles introduced into the ware washer to be separated from the wash liquid used to wash the wash ware, it is generally known to used filter devices in the form of dirt filter baskets, in which the dirt particles introduced into the ware washer are collected. In the case of ware washers configured as box-type ware washers, such a dirt filter basket is normally arranged in the sump of the treatment chamber, above the wash tank.

On the other hand, with regard to ware washers which are configured as conveyer ware washers, it is known for at least the pre-wash tank, which is associated with the pre-wash zone, and preferably also the main wash tank, which is associated with the at least one main wash zone, to be equipped with planar filters and dirt filter baskets.

During operation of the ware washer, configured either as a box-type ware washer or as a conveyer ware washer, the dirt particles washed off the wash ware by means of the circulating wash water then fall onto the planar filters as a result of gravity. There, the dirt particles are separated from the wash liquid flowing back into the corresponding wash tank. The separated dirt particles are then normally washed into a dirt filter basket.

The present invention is based on the problem that, in the solutions known hitherto from the prior art, in which use is made of planar filters or dirt filter baskets for separating dirt particles from a circulating wash liquid, there is the risk that the dirt particles accumulating on the planar filter or in the dirt filter basket are comminuted by the permanent circulation of the wash liquid to such an extent as the washing time increases that the dirt particles have a particle size which is no longer covered by the mesh size of the planar filter or of the dirt filter basket, so that, despite the provision of a planar filter or dirt filter basket, the situation in which dirt particles increasingly accumulate in the wash liquid as the washing time increases can no longer be prevented.

In this context, the document DE 10 2009 048 810 A1 has disclosed that the at least one wash zone of the ware washer is assigned a dirt catching system, which comprises a tank cover filter for separating dirt particles from the sprayed wash liquid which flows back into the wash tank of the wash zone, configured as a recirculation circuit, as a result of gravity. The dirt catching system known from this prior art comprises a dirt collection region in which the dirt particles separated from the wash liquid by means of the tank cover filter are collected. The dirt collection region is connected fluidically to a dirt discharge pipe system such that, by means of a dirt discharge pump, the dirt particles collected in the dirt collection region of the dirt catching system are able be removed when required.

The dirt catching system known from the document DE 10 2009 048 810 A1 has disadvantages in practical use, however, in particular concerning the dirt discharge capacity actually realized during the operation of the ware washer. It has been found that, for emptying the dirt collection region, the dirt discharge pump has to be operated continuously over a relatively long period of time. During this period of time, recirculation of the wash liquid in the wash zone should be interrupted too. However, this has the consequence that a continuous rinsing or washing operation is influenced by way of the conventional dirt discharge system. In particular, the dirt discharge system known from DE 10 2009 048 810 A1 leads to an extension of the program cycles that is often not able to be accepted by the ware washer operators, or to a reduction in the quantity of items of wash ware washed by the ware washer per unit of time.

Accordingly, the present invention is based on the object, proceeding from a dirt catching system as is known, at least in principle, from DE 10 2009 048 810 A1, of further developing said dirt catching system such that, in an effective but nevertheless easily realizable manner, the risk of recontamination of the wash ware can be reduced and the washing result can be improved overall, on the one hand, and the operation and in particular the washing capacity of the ware washer is not adversely affected, on the other hand.

Said object is achieved according to the invention in that, in a ware washer of the type mentioned in the introduction, a dirt catching system which is associated with the at least one wash system of the ware washer is provided, wherein the dirt catching system has associated therewith a tank cover filter which is configured to separate dirt particles from the sprayed wash liquid which flows back into the wash tank as a result of gravity. As also in the case of dirt catching system known from the document DE 10 2010 063 711 A1, the dirt catching system according to the invention comprises a dirt collection region which is arranged at least in part in the wash tank and is upwardly open and serves for collecting the dirt particles separated from the wash liquid by means of the tank cover filter.

In the solution according to the invention, in addition, a dirt discharge system which is connected fluidically to the dirt collection region is provided with a dirt discharge pipe system by means of which the dirt collection region is able to be emptied when required.

The solution according to the invention is characterized in particular in that the dirt collection region of the dirt catching system has associated therewith a pressure equalizing system for being able to equalize, by means of said pressure equalization system, a negative pressure which builds up locally in the dirt collection region when the dirt collection region is emptied.

The advantages obtainable with the solution according to the invention are self-evident: in that the dirt collection region has associated therewith a pressure equalizing system for equalizing the negative pressure which builds up locally in the dirt collection region when the dirt collection region is emptied, the process for emptying the dirt collection region, and in particular the length of time required for this purpose, is shortened in comparison with a dirt catching system having a dirt collection region as is known from the document DE 10 2010 063 711 A1. It has been recognized here that, by means of the pressure equalization system, not only can the negative pressure building up locally in the dirt collection region be reduced or equalized, but in addition thereto a vortex flow is formed in the dirt collection region when the dirt collection region is emptied, with which vortex flow the wash liquid, laden with dirt particles, rotates in the dirt collection region and in this way the emptying of the dirt collection region is significantly sped up.

As a consequence thereof, a regular discharge of dirt during the continuous operation of the ware washer is able to be realized without, for this purpose, the running time of the ware washer having to be extended. Consequently, not only is the risk of recontamination of the wash ware reduced (since the quality of the wash liquid is optimized due to a regular discharge of dirt), but also the capacity of the ware washer is not adversely affected.

There are various possibilities for the realization of the pressure equalizing system. In particular, the pressure equalizing system may be configured at least in regions in a side wall of the dirt collection region. In this case, the pressure equalization system may comprise for example a flexible wall region which, during the emptying process of the dirt collection region, is deformed into the dirt collection region in order, in this way, to equalize a negative pressure which builds up locally in the dirt collection region when the dirt collection region is emptied.

Alternatively, the pressure equalization system comprises a wall region which is permeable to wash liquid and preferably not permeable to dirt particles, such as for example a filter, in particular a fine filter. Alternatively, slot-like openings or point-like openings are also conceivable. The permeable wall region or the filter and/or the slot-like or point-like openings are preferably formed peripherally in the side wall of the dirt collection region in such a manner that vortex formation in the wash liquid, laden with dirt particles, in the dirt collection region is promoted when the dirt collection region is emptied.

According to the invention, the dirt discharge system comprises a dirt discharge pump, the suction side of which is connected or connectable fluidically to the dirt collection region. As an alternative to a dirt discharge pump, it is also conceivable for an actuatable valve to be provided in the dirt discharge pipe system, such that the dirt collection region is able to be emptied, as a result of gravity, when required, specifically when the valve is open. The provision of a dirt discharge pump is preferable, however, since, with such a dirt discharge pump, the time to be provided for the emptying of the dirt collection region can be significantly reduced.

On the other hand, if a dirt discharge pump is used, it has to be ensured that it is indeed substantially only the wash liquid laden with dirt particles and collected in the dirt collection region that is removed via the dirt discharge pump. For this purpose, according to embodiments of the present invention, it is provided that the pressure equalizing system is configured in a side wall of the dirt collection region between a connecting piece, by means of which the dirt collection region is connected or connectable fluidically to the dirt discharge pipe system, and the opposite upper end region of the dirt collection region. In particular, the pressure equalization system should in this case, wherever possible, be provided in a central or upper region of the dirt collection region. It is particularly efficient if the pressure equalizing system is configured in a region of the side wall of the dirt collection region above a level of 30% of the length of the dirt collection region measured from the connecting piece to the upper end region of the dirt collection region.

The dirt collection region should comprise a capacity of at least 0.5 l and at most 3.0 l . Preferably, the capacity of the dirt collection region lies in a range of between 1.0 l and 2.0 l. This involves a compromise in which both the time required for emptying the dirt collection region and the frequency of an emptying process to be carried out for the dirt collection region are taken into consideration.

Furthermore, it is provided according to the invention in particular that the dirt discharge pipe system and the suction-side inlet and pressure-side outlet of the dirt discharge pump comprises an effective diameter which is larger in comparison with wash pumps used in ware washers, in particular an effective diameter of at least 5 cm. This, too, has a positive effect regarding the time required for emptying the dirt collection region.

The provision of the pressure equalizing system makes it possible for the dirt collection region to be emptied in an extremely short time. In particular, it allows the solution according to the invention to use a dirt discharge pump comprising a pump capacity of at least 100 l per minute and preferably a pump capacity of at least 110 l per minute.

In particular, the solution according to the invention provides an effective method for discharging dirt particles from the wash liquid, so that a longer service life for the wash liquid in comparison with conventional solutions is able to be realized. In this way, it is possible for the wash liquid to be used for a greater number of wash cycles before it has to be replaced. This saves in particular fresh water, cleaning agent and heating energy.

Preferably, the dirt discharge pump is designed to remove the dirt particles collected in the dirt collection region from the wash zone continuously or at given times and/or events.

Accordingly, the solution according to the invention allows the dirt particles collected in the at least one wash zone of the ware washer by means of the dirt catching system also to be removable from the ware washer automatically. Such dirt discharge, carried out automatically, relieves the personnel operating the ware washer. Moreover, influencing or blocking of the recirculation of the wash liquid in the wash zone due to overfilling of the dirt collection region can be prevented in an effective manner.

Exemplary embodiments of the solution according to the invention will be described in more detail below with reference to the appended drawings.

In the drawings:

• FIGURE 1 schematically shows a ware washer, configured in the form of a conveyer ware washer, according to a first embodiment of the invention;
• FIGURE 2 schematically shows a ware washer, configured in the form of a conveyer ware washer, according to a second embodiment of the invention;
• FIGURE 3 schematically shows a ware washer, configured in the form of a conveyer ware washer, according to a third embodiment of the invention; and
• FIGURE 4 schematically shows the wash tank of a wash zone of a ware washer, configured as a conveyer ware washer or as a box-type ware washer, with an embodiment of a dirt catching system.

FIGURE 1 shows, in a schematic longitudinal sectional view, an example of a conveyer ware washer 50 configured according to the teachings of the present invention. The conveyer ware washer 50 according to the illustration in FIGURE 1 comprises a pre-wash zone 51 and a main wash zone 52, which, as seen in the conveying direction T of the wash ware (not illustrated in FIGURE 1), is arranged downstream of the pre-wash zone 51. As seen in the conveying direction T, downstream of the main wash zone 52 there are arranged in the conveyer ware washer 50 illustrated in FIGURE 1 a post-wash or pre-rinse zone 53 and a final rinse zone 54, connected downstream of the post-wash or pre-rinse zone 53. The wash ware, either received directly on a conveyer belt 58 or held by racks, runs, in the conveying direction T, through an entry 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.

Said treatment zones 51, 52, 53, 54 of the conveyer ware washer 50 each have associated therewith spray nozzles 13-1, 13-2, 13-3, 13-4 via which liquid is sprayed onto the wash ware which is being conveyed by the conveyer belt 58 through the respective treatment zones 51, 52, 53, 54. At least the pre-wash zone 51, the main wash zone 52 and the post-wash or pre-rinse zone 53 each have associated therewith a tank (wash tank 14-1, 14-2, 14-3) in which sprayed wash liquid is received and/or in which wash liquid for the spray nozzles 13-1, 13-2, 13-3 of the respective zones 51, 52, 53 is provided.

The pre-wash zone 51, the main wash zone 52 and the post-wash zone 53 of the conveyer ware washer 50 according to the first embodiment of the invention illustrated in FIGURE 1 each comprise a wash system 10-1, 10-2, 10,3. Each wash system 10-1, 10-2, 10-3 is composed of a wash pump 11-1, 11-2, 11-3, a line system 12-1, 12-2, 12-3, which is connected to the wash pump 11-1, 11-2, 11-3, and the spray nozzles 13-1, 13-2, 13-3, which are connected to the line system 12-1, 12-2, 12-3.

Furthermore, provision is made of a control device 100 (illustrated schematically in the figures), which serves (inter alia) for suitably actuating the respective wash pumps 11-1, 11-2, 11-3 of the wash systems 10-1, 10-2, 10-3 during a wash process, in order, at least intermittently, to feed wash liquid 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 wash system 10-1, 10-2, 10-3.

In the conveyer ware washer 50 illustrated in FIGURE 1, final rinse liquid in the form of fresh water, which may be mixed with further, chemical additives, such as for example rinse aid, is sprayed via the spray nozzles 13-4, arranged above and below the conveyer belt 58, of the final rinse zone 54 onto the wash ware (not illustrated in FIGURE 1). As illustrated in FIGURE 1, laterally arranged spray nozzles 13-5 may also be provided in the final rinse zone 54.

Part of the final rinse liquid sprayed in the final rinse zone 54 is conveyed via a cascade system from zone to zone in the direction opposite the conveying direction T of the wash ware. The remaining part is conducted via a valve 59 and a bypass line 60 directly into the pre-wash tank 14-1 of the pre-wash zone 51.

The final rinse liquid sprayed in the final rinse zone 54 is caught 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 via the wash pump 11-3 belonging to the wash system 10-3 of the post-wash or pre-rinse zone 53 to the spray nozzles 13-3 (post-wash or pre-rinse nozzles) of the post-wash or pre-rinse zone 53. Wash liquid is rinsed off the wash ware in the post-wash or pre-rinse zone 53.

The liquid occurring here flows into the wash tank 14-2 of the main wash zone 52, is normally provided with a chemical cleaning agent and, by means of a wash pump 11-2 belonging to the wash system 10-2 of the main wash zone 52, is sprayed via the spray nozzles 13-2 (wash nozzles) of the wash system 10-2 belonging to the main wash zone 52 onto the wash ware.

From the wash tank 14-2 of the main wash zone 52, the wash liquid subsequently flows into the pre-wash tank 14-1 of the pre-wash zone 51. In the pre-wash zone 51, the wash liquid collected in the pre-wash tank 14-1 is, by means of a wash pump 11-1 belonging to the wash system 10-1 of the pre-wash zone 51, sprayed via the spray nozzles 13-1 (pre-wash nozzles) of the wash system 10-1 belonging to the pre-wash zone 51 onto the wash ware, in order to remove coarse impurities from the wash ware.

In the conveyer ware washer 50 illustrated in FIGURE 1, the main wash zone 52 comprises a tank cover filter 20-2 which is arranged above the main wash tank 14-2. During operation of the conveyer ware washer 50, wash liquid is sprayed via the spray nozzles 13-2 (wash nozzles) of the wash system 10-2 onto the wash ware. The sprayed wash liquid flows back into the wash tank 14-2 of the main wash zone 52 as a result of gravity, wherein the dirt particles rinsed off the wash ware in the main wash zone 52 are retained by the tank cover filter 20-2, provided that the dirt particles are larger than the mesh size of the tank cover filter 20-2. Preferably, the mesh size of the tank cover filter 20-2 is approximately 1 mm to 4 mm.

In the conveyer ware washer 50 schematically illustrated in FIGURE 1, for the purpose of cleaning the tank cover filter 20-2, the rinse operation has to be interrupted in order to allow the tank cover filter 20-2 to be cleaned manually.

Part of the wash liquid sprayed in the main wash zone 52 passes via an overflow system 61 into the wash tank (pre-wash tank 14-1) of the pre-wash zone 51. Like the main wash zone 52, the pre-wash zone 51 is equipped with a tank cover filter 20-1 configured as a planar filter. Said tank cover filter 20-1 is arranged above the wash tank (pre-wash tank 14-1) of the pre-wash zone 51 in order to separate dirt particles from the wash liquid which has been sprayed in the pre-wash zone 51 and is flowing back into the pre-wash tank 14-1 as a result of gravity. The mesh size of the tank cover filter 20-1 preferably lies in a range between approximately 1 mm and 4 mm.

Since - as explained in the introduction - the concentration of dirt in the wash liquid is at its greatest in the pre-wash zone 51, since this is where the most dirt occurs, the conveyer ware washer 50 illustrated in FIGURE 1 is equipped with a dirt catching system 70 which is associated with the pre-wash zone 51 and which comprises a dirt collection region 71-1 arranged in the pre-wash zone 51 and in particular within the pre-wash tank 14-1. The construction and the functioning of the dirt catching system 70 used in the conveyer ware washer 50 illustrated in FIGURE 1 is described in more detail below with reference to the illustration in FIGURE 4.

In that embodiment of the conveyer ware washer 50 which is illustrated in FIGURE 1, the dirt collection region 71 serves for collecting the dirt particles separated from the wash liquid by means of the tank cover filter 20-1. Specifically, and as described in more detail below with reference to the illustration in FIGURE 4, the dirt collection region 71-1 is configured as a chamber which is arranged in the pre-wash tank 14-1 and which is open toward the top and which comprises a pressure equalizing system at its sides. Via the upper opening, the dirt particles separated out by means of the tank cover filter 20-1 can pass into the chamber-like dirt collection region 71-1. The fact that the dirt collection region 71 comprises a pressure equalizing system at the sides means that particularly quick emptying of the dirt collection region 71 is able to be realized.

Specifically, and as described in more detail below with reference to the illustration in FIGURE 4, it is preferable for the tank cover filter 20-1 to be arranged above the dirt collection region 71-1 and to comprise a drainage slope in the form of an incline directed toward a feed opening 22, wherein the dirt collection region 71-1, which is configured upwardly open, is arranged below the feed opening 22 in such a manner that the dirt particles separated out by means of the tank cover filter 20-1 can pass via the feed opening 22 into the dirt collection region 71-1.

Here, it is conceivable in particular that the tank cover filter 20-1 is configured in a funnel-shaped manner at least in regions, wherein the feed opening 22 is configured inside the funnel-shaped region 21 of the tank cover filter 20-1, and preferably at the apex of the funnel-shaped region 21 of the tank cover filter 20-1 (cf. in this respect also in particular the illustration in FIGURE 4).

The dirt catching system 70 used in the embodiment illustrated in FIGURE 1 also comprises a dirt discharge pipe system which is connected to the dirt collection region 71-1 and which consists of a vertical pipe 72-1 and a dirty-water line 73-1 and which serves for discharging from the pre-wash zone 51 the dirt particles collected in the dirt collection region 71-1. As illustrated, a dirt discharge pump 74-1 is arranged in the dirt discharge pipe system 72-1, 73-1. The inlet, on the suction side, of the dirt discharge pump 74-1 is connected to the lower region of the dirt collection region 71-1 via the vertical pipe 72-1 belonging to the dirt discharge pipe system. The outlet, on the pressure side, of the dirt discharge pump 74-1 opens in the dirty-water line 73-1 belonging to the dirt discharge pipe system.

In the embodiment illustrated in FIGURE 1, the dirty-water line 73-1 leads to an external dirt catching container 80, which is arranged outside the pre-wash zone 51 upstream of the entry tunnel 55 of the conveyer ware washer 50. This external dirt catching container 80 preferably comprises a filter and a connection 81 to a wastewater system.

Since, when wash liquid is sprayed in the pre-wash zone 51, it is not possible to prevent part of the sprayed wash liquid from passing into the dirt collection region 71, not only the dirt particles separated out by means of the tank cover filter 20-1 but also part of the wash liquid are delivered from the pre-wash zone 51 via the dirt discharge pump 74-1. The material removed from the dirt collection region 71-1 (dirt particles and wash liquid) is filtered in the dirt catching container 80, wherein the liquid constituent parts (wash liquid) can be fed to a wastewater system via the outflow connection 81 and the solids remaining in the dirt catching container 80 (dirt particles) can subsequently be disposed of.

As illustrated in FIGURE 2, it is, as an alternative to the embodiment illustrated in FIGURE 1, also conceivable for the dirt particles to be pumped with the wastewater out of the pre-wash zone 51 into a waste disposal system 82, wherein said system 82 may be positioned in terms of location either directly adjacent to the conveyer ware washer 50 or else further away. Squeezing-out systems for separating solids and liquids and/or comminuting systems (grinding systems, chopping systems, etc) may be used as a waste disposal system 82.

The material removed from the dirt collection region 71-1 (dirt particles and wash liquid) is preferably likewise filtered in the waste disposal system 82, wherein the liquid constituent parts (wash liquid) can be fed to a wastewater system via an outflow connection 83 and the solids remaining in the waste disposal system 82 (dirt particles) can subsequently be disposed of.

According to embodiments of the solution according to the invention, it is provided that the material removed from the dirt collection region 71-1 (dirt particles and wash liquid) is fed to a heat recovery system (heat exchanger) in order to "recover" at least a portion of the thermal energy of the material removed from the dirt collection region 71-1 and to use this for heating the liquids to be sprayed in the ware washer (wash liquid or final rinse liquid).

For example, it is conceivable that, firstly, the material removed from the dirt collection region 71-1 is filtered, wherein subsequently only the liquid constituent parts (wash liquid) are fed to the heat recovery system. In this way, it is possible to reduce the risk of a blockage or fault due to dirt particles in an effective manner.

Alternatively or additionally, it is also conceivable that, after the dirt particles are separated from the material removed from the dirt collection region 71-1, the liquid constituent parts (wash liquid) are possibly treated in such a manner that the liquid constituent parts can be fed back to the wash system of the ware washer. A treatment possibly to be carried out could be filtration.

FIGURE 3 illustrates a further embodiment of the conveyer ware washer 50 configured according to the teachings of the present invention. This embodiment is substantially identical to the embodiment described above with reference to the illustration in FIGURE 1 or FIGURE 2, albeit with the exception that not only the pre-wash zone 51 but also the main wash zone 52 is equipped with a dirt catching system 70, the construction and functioning of which will be described in more detail below with reference to the illustration in FIGURE 4.

By contrast to the embodiment illustrated in FIGURE 1, in the conveyer ware washer 50 shown in FIGURE 3, there is consequently provided in or above the main wash tank 14-2 a tank cover filter 20-2 which comprises a feed opening 22 (cf. FIGURE 4), wherein a dirt collection region 71-2, which is configured upwardly open, is arranged below the feed opening 22. In said dirt collection region 71-2, the dirt particles separated out by means of the tank cover filter 20-2 are introduced into the dirt collection region 71-2 via the feed opening 22.

In that embodiment of the solution according to the invention which is illustrated in FIGURE 3, a dirt discharge pipe system consisting of a dirty-water line 73-2 and a vertical pipe 72-2 is provided at the lower region of the dirt collection region 71-2. The material collected in the dirt collection region 71-2 (wash liquid and separated dirt particles) passes via a dirt discharge pump 74-2 into a dirt catching container 80 formed externally of the main wash zone 52 or into a waste disposal system 82 formed externally of the conveyer ware washer 50.

The construction and the functioning of the dirt catching system 70 are described in more detail below with reference to the illustration in FIGURE 4.

The dirt catching system 70 is arranged within a wash tank 14 of a conveyer ware washer 50 or of a ware washer configured as a box-type ware washer. The dirt catching system 70 comprises a tank cover filter 20 which is preferably arranged in the wash tank 14 above the liquid level of the wash liquid received in the wash tank 14. The tank cover filter 20 serves for separating dirt particles from the wash liquid which has been sprayed and is flowing back into the wash tank as a result of gravity. For this reason, the tank cover filter 20 is to be provided with a suitable mesh size.

A dirt collection region 71 which is configured as an upwardly open chamber also belongs to the dirt catching system 70. The dirt particles separated out by the tank cover filter 20 are fed via the opening of the dirt collection region 71 configured as a chamber to the dirt collection region 71. For this purpose, it is preferable for the tank cover filter 20 to comprise a drainage slope in the form of an incline directed toward a feed opening 22, wherein the dirt collection region 71, which is configured upwardly open, is arranged below the feed opening 22.

As indicated in FIGURE 4, there is provided in particular in the upper region of the side wall of the dirt collection region 71 a pressure equalizing system 90, which is shown schematically there. In that embodiment of the dirt catching system 70 which is shown schematically in FIGURE 4, the pressure equalizing system 90 is formed by a wall region in the side wall of the dirt collection region 71, which wall region is permeable to wash liquid. In particular, it is conceivable for a fine filter to be used as the pressure equalizing system.

Alternatively or additionally, other openings, in particular slot-like or point-like openings, in particular for promoting vortex formation of the wash liquid, laden with dirt particles, in the dirt collection region 71, are also conceivable.

It can furthermore be seen in FIGURE 4 that the pressure equalizing system 90 is configured in a region of the side wall of the dirt collection region 71 above a level of 30% of the length of the dirt collection region 71 measured from the connecting piece 75 to the upper end region of the dirt collection region 71. As a result of this arrangement, a situation in which, during operation of the dirt discharge pump, uncontaminated wash liquid is sucked in via the pressure equalizing system 90, configured for example as a fine filter, is prevented in an effective manner.

As illustrated in FIGURE 4, it is conceivable for example that the tank cover filter 20 is configured in a funnel-shaped manner at least in regions, wherein the feed opening 22 is configured inside the funnel-shaped region 21 of the tank cover filter 20, and preferably in the tapered region of the funnel-shaped region 21 of the tank cover filter 20.

It is furthermore preferable for the dirt collection region 71 to be configured in a funnel-shaped manner at the upper end (cf. the funnel-shaped region 75 in FIGURE 4), so as to be able to be inserted into, or received inside, the feed opening 22 of the tank cover filter 20.

During operation of the ware washer (not shown in FIGURE 4), wash liquid is sprayed in the wash zone, wherein part of the sprayed wash liquid flows back into the wash tank 14 via the tank cover filter 20. The remaining part of the sprayed wash liquid flows, as a result of gravity, directly into the dirt collection region 71 via the feed opening 22 provided in the tank cover filter 20. The dirt particles rinsed off the wash ware during the wash process are prevented by the tank cover filter 20 from passing into the wash liquid collected in the wash tank 14, provided that they are larger than the mesh size of the tank cover filter 20. Rather, the dirt particles separated out by the tank cover filter 20 are moved to the feed opening 22 by way of the drainage slope and thereby pass into the dirt collection region 71.

In order for it to be possible for the dirt collection region 71 to be emptied preferably automatically, the dirt catching system 70 preferably also comprises a dirt discharge pipe system. In that embodiment of the dirt discharge system which is illustrated in FIGURE 4, said dirt discharge pipe system consists of a vertical pipe 72 which is connected to the lower region of the dirt collection region 71. The vertical pipe 72 is connected to the inlet, on the suction side, of a dirt discharge pump 74. The outlet, on the pressure side, of the dirt discharge pump 74 opens in a dirty-water line 73, with the result that, when the dirt discharge pump 74 is activated, the contents of the dirt collection region 71 can be removed from the wash zone.

The dirt discharge pump 74 is preferably designed to remove the dirt particles collected in the dirt collection region 71 together with the wash liquid likewise collected in the dirt collection region 71 continuously or at given times and/or events. It is in particular conceivable here for the dirt discharge pump 74 to be actuated via the already mentioned control unit 100 in dependence on the quantity of dirt particles collected in the dirt collection region 71.

Nevertheless, it is of course conceivable for dirt to be pumped out of the dirt collection region 71 in dependence on, for example, the level in the dirt collection region 71, the level in the wash tank 14, or other factors.

If the dirt catching system 70 is used in a conveyer ware washer 50 (cf. for example FIGURE 1 to FIGURE 3), it is furthermore conceivable for the dirt discharge pump 74 to be activated for example in dependence on the conveying speed at which the wash ware is conveyed through the treatment zones of the conveyer ware washer 50, or for example in dependence on the quantity of final rinse liquid sprayed in the final rinse zone 54 per unit of time.

The invention is not restricted to the embodiments described in conjunction with the drawings.

In this regard, it is conceivable for example for the tank cover filter 20, 20-1, 20-2 of the dirt catching system 70 not to comprise a substantially centrally arranged feed opening 22 via which the dirt particles separated out by means of the tank cover filter 20, 20-1, 20-2 pass into the dirt collection region 71, 71-1, 71-2. Rather, said feed opening 22 may also be configured as a gap which is provided at an edge region of the tank cover filter 20, 20-1, 20-2.

Furthermore, it is in principle conceivable for the feed opening 22 to be covered by means of a coarse filter, wherein said coarse filter should preferably have a mesh size which is larger than the mesh size of the tank cover filter 20, 20-1, 20-2. The provision of such a coarse filter can, in an effective manner, prevent for example items of cutlery or other utensils, as opposed to dirty-water particles, from inadvertently passing into the dirt collection region 71, 71-1, 71-2.

Although a description has been given of the solution according to the invention in figures 1 to 3 in conjunction with a conveyer ware washer 50, it is of course also conceivable for a ware washer configured as a box-type ware washer to be equipped with a dirt catching system 70.