Patent Publication Number: US-2013240001-A1

Title: Conveyor dishwasher

Description:
The invention relates to a conveyor dishwasher and, in particular, to a conveyor dishwasher having at least one wash zone and at least one final rinse zone and also having a conveyor apparatus for conveying washware through the at least one wash zone and the at least one final rinse zone. 
     The conveyor dishwasher according to the invention is, in particular, a commercial conveyor dishwasher and can be in the form of a flight-type dishwasher (flight-type warewasher) or a rack-conveyor dishwasher (rack-conveyor warewasher). 
     Conveyor dishwashers (conveyor warewashers) are used in the commercial sector. In contrast to domestic dishwashers, in which the washware to be cleaned remains stationary in the machine during cleaning, in conveyor dishwashers the washware is conveyed through various treatment zones of the machine. 
     In the case of conveyor dishwashers, the washware, for example trays, tableware, pots, glasses, cutlery and other articles which are to be cleaned, is conveyed through a plurality of treatment zones, for example prewash zone(s), main wash zone(s), postwash or prerinse zone(s), final rinse zone(s) and drying zone(s). A conveyor apparatus which generally has compartments for holding washware is used to convey washware in a conveying direction through the conveyor dishwasher. In the case of a flight-type dishwasher, the compartments can be formed by supporting fingers on a conveyor belt of the conveyor apparatus. In the case of rack-conveyor dishwashers, dish racks in which compartments can be formed in order to hold the washware to be treated serve as the conveyor apparatus. It is feasible here for the dish racks to be conveyed through the rack-conveyor dishwasher by a conveying device. 
     The washware to be cleaned is usually presorted before being placed on the conveyor belt. For example, U.S. Pat. No. 6,530,996 B2 discloses a rack-conveyor dishwasher in which the washware to be treated is fed to the respective treatment zones in a state in which it is presorted in dish racks. 
     With regard to tray or tray-like articles, the presorting process is usually performed by the set of tableware and cutlery being removed from a tray to be cleaned and the tray then being stacked in front of the conveyor apparatus or in the feed region (dirty side) of the conveyor dishwasher. The trays from this stack of trays are from time to time placed, in manner sorted by type, in the conveyor belt of the dishwasher and cleaned. This procedure of sorting by type has the advantage that trays cannot cast spray shadows over smaller items of washware which have been stacked behind the trays. Furthermore, this procedure greatly simplifies the sequence of work for stacking and destacking and makes it more efficient in comparison to mixing the washware with the trays to be cleaned. 
     However, while the trays from this stack of trays are placed, in a manner sorted by type, in the conveyor belt of the dishwasher and cleaned, it is not possible to clean other washware, for example plates, bowls or other tableware, since the trays which are to be placed in the conveyor belt usually have to be placed in the conveyor belt transverse to the conveying direction and therefore take up all the available surface area of the conveyor belt. Therefore, a relative large amount of time is required to clean trays in comparison to other types of washware. 
     Furthermore, the operating personnel of the conveyor dishwasher at the machine inlet have to include each tray twice in their sequence of work: the first time when removing the items of cutlery and tableware from the tray to be cleaned and the second time when actually placing the tray in the conveyor belt of the conveyor dishwasher. 
     On the basis of this problem, the object of the present invention is to develop a conveyor dishwasher of the type cited in the introductory part in such a way that this enables the entire washing and rinsing process to be made more efficient, as a result of which, in particular, the working time of the dishwashing personnel can be reduced and the consumption of resources by the dishwasher can be reduced. 
     According to the invention, this object can be achieved by the subject matter claimed below. 
     In this regard, a typical tray or tray-like item of washware has a lengthwise dimension and a widthwise dimension, where the widthwise dimension is smaller than the lengthwise dimension. The end edges of the tray or tray-like washware item define the lengthwise dimension and the sides edges of the tray or tray-like washware item define the widthwise dimension. 
     In accordance with the subject matter, the invention proposes that the conveyor apparatus of the conveyor dishwasher has a first conveyor belt for trays or tray-like washware, and a second conveyor belt, which runs parallel to the first conveyor belt, for other washware, with the first conveyor belt having a width which is reduced in comparison to the second conveyor belt in such a way that a tray or a tray-like item of washware can be held by the first conveyor belt only when it is in a state in which it is placed on edge and is oriented parallel to the conveying direction. 
     The tray or tray-like washware may typically be placed on either an end edge or a side edge on the first conveyor belt. The tray or tray-like washware item is considered oriented parallel to the conveying direction if either the lengthwise dimension or the widthwise dimension of the tray or tray-like washware item runs substantially paralallel to the conveying direction. 
     The term “width of the conveyor belt” used here is to be understood to mean the horizontal extent of the conveyor belt transverse, that is to say perpendicular, to the conveying direction. 
     Since a separate conveyor belt (first conveyor belt) is provided in the conveyor dishwasher according to the invention for trays or tray-like articles, it being possible for trays or tray-like articles to be in a state in which they are placed on edge and are oriented parallel to the conveying direction in the conveyor belt, it is possible for the trays or tray-like articles to be cleaned with other washware at the same time, without the risk of the trays or tray-like articles casting a spray shadow on the washware which is to be cleaned at the same time as the trays or tray-like articles during cleaning. 
     Furthermore, the orientation of the trays or tray-like articles parallel to the direction in which the first and second conveyor belts run results in minimal utilization of the surface area of the total belt surface area. This minimal utilization of surface area means that the second conveyor belt, which is provided for the other washware, can continue to be used virtually without restriction. Both racks of glasses and GN containers can be placed on the second conveyor belt next to a tray which is disposed on the first conveyor belt. 
     Therefore, the arrangement of two conveyor belts reduces the length of the overall washing and rinsing process in a commercial scullery and therefore reduces the working time of the dishwashing personnel and also, secondly, reduces the consumption of resources by the conveyor dishwasher. 
     In a preferred embodiment of the solution according to the invention, provision is made for the conveying speed of the first conveyor belt to be increased relative to the conveying speed of the second conveyor belt. This increase in the conveying speed enables each tray to be placed in position, without delay, at the time at which all the items of cutlery and tableware are removed from the tray. Accordingly, it is possible for the trays to not be deposited in a stack after the items of tableware and cutlery possibly present on the tray are removed from them, but rather for the trays to be placed directly into the first conveyor belt. Therefore, a second working step involving the respective tray is dispensed with in this embodiment. Automatic destacking of trays at the machine outlet is likewise preferred for this machine configuration since, under certain circumstances, the operating personnel at the machine outlet may be unable to cope with destacking the conveyor dishwasher on account of the cleaning processes running in parallel on the two conveyor belts. 
     The concept of providing a separate conveyor belt for specific types of washware can be extended as desired and various combinations of individual conveyor belts are possible. Therefore, in a preferred embodiment of the solution according to the invention, provision is also made for at least one further conveyor belt, which runs parallel to the first and second conveyor belts, to be used, with this further conveyor belt preferably being provided for items of cutlery. In this case, it is preferred when the further conveyor belt which is provided for items of cutlery runs directly next to the first conveyor belt and between the first and second conveyor belts. In this embodiment, it is no longer necessary for the operator of the conveyor dishwasher to manually remove the set of cutlery from the respective tray at the machine inlet. Since the tray is placed on edge in order to be fed and placed on the first conveyor belt, the set of cutlery falls automatically—driven by the force of gravity—from the upended tray into the cutlery lane (further conveyor belt) and likewise into a provided container after washing and drying. Therefore, the handling actions for the cutlery are completely dispensed with. 
     Furthermore, special lanes for individual types of washware, for example plates and/or bowls, can be provided since automatic destacking systems for all these types of washware are already known from semi- and fully automatic technology. On account of the degree of automation which is increased by virtue of these special lanes in conjunction with automated destacking, working time can be saved both at the clean end and at the dirty end of the conveyor dishwasher. The dishwashing process therefore runs more efficiently and its overall length is reduced, so that, in addition to working time, resources can be saved. 
    
    
     
       The invention will be described below by way of example on the basis of various embodiments and with reference to the drawings. Parts which are the same or have the same functions are provided with the same reference numerals here. 
       In the drawings: 
         FIG. 1  shows a schematic longitudinal view of a conveyor dishwasher in which a conveyor apparatus according to the invention can be used to treat (clean and dry) a plurality of types of washware, which are arranged next to one another, at the same time; 
         FIG. 2   a  shows a plan view of a sub-region of a first exemplary embodiment of a conveyor apparatus which can be used in a conveyor dishwasher according to  FIG. 1 ; 
         FIG. 2   b  shows a cross-sectional view of the conveyor apparatus according to  FIG. 2   a;    
         FIG. 3   a  shows a plan view of a sub-region of a second exemplary embodiment of a conveyor apparatus which can be used in a conveyor dishwasher according to  FIG. 1 ; 
         FIG. 3   b  shows a cross-sectional view of the conveyor apparatus according to  FIG. 3   a;    
         FIG. 4   a  shows a plan view of a sub-region of a third exemplary embodiment of a conveyor apparatus which can be used in a conveyor dishwasher according to  FIG. 1 ; and 
         FIG. 4   b  shows a cross-sectional view of the conveyor apparatus according to  FIG. 4   a.    
     
    
    
       FIG. 1  shows a schematic longitudinal view of an exemplary embodiment of a conveyor dishwasher  1  in which a conveyor apparatus  2  is used for conveying washware (not illustrated in  FIG. 1 ) through the conveyor dishwasher  1  in a conveying direction T. As will be described later with reference to the illustrations in  FIGS. 2 to 4 , the conveyor apparatus  2  is designed, according to the invention, to treat (clean and dry) a plurality of types of washware, which are arranged next to one another, at the same time, in order to thus make the entire washing and rinsing process more efficient, as a result of which, in particular, the working time of the dishwashing personnel can be reduced and the consumption of resources by the dishwasher can be reduced. 
     As can be seen in the illustration in  FIG. 1 , the conveyor dishwasher  1  according to the exemplary embodiment has at least one wash zone (as illustrated in  FIG. 1  for example), a prewash zone  10  and two main wash zones  11 . 1 ,  11 . 2  which are arranged downstream of the prewash zone  10  as seen in the conveying direction T. 
     As seen in the conveying direction T, a postwash zone  12  is arranged downstream of the at least one wash zone  10 ,  11 . 1 ,  11 . 2 , and at least one final rinse zone, for example only a single final rinse zone  13  as illustrated, is arranged downstream of the postwash zone  12 . In the conveyor dishwasher  1  illustrated in  FIG. 1 , the final rinse zone  13  is followed in the conveying direction T of the washware by a drying zone  14 . 
     The respective zones  10 ,  11 . 1 ,  11 . 2 ,  12 ,  13 ,  14  of the conveyor dishwasher  1  can be separated from one another by means of separating curtains  5 . In the embodiment illustrated in  FIG. 1 , the inlet tunnel  3  of the conveyor dishwasher  1  itself is also separated from the inlet  4  by means of a separating curtain  5 . The provision of the separating curtains  5  prevents wash liquid and final rinse liquid spraying between zones and prevents vapours escaping from the conveyor dishwasher  1 . 
     The treatment zones  10 ,  11 . 1 ,  11 . 2 ,  12 ,  13  of the conveyor dishwasher  1  have associated spray nozzles  30   a ,  30   b ,  31 . 1   a ,  31 . 1   b ,  31 . 2   a ,  31 . 2   b ,  32   a ,  32   b ,  33   a ,  33   b ,  33   c . These spray nozzles  30   a ,  30   b ,  31 . 1   a ,  31 . 1   b ,  31 . 2   a ,  31 . 2   b ,  32   a ,  32   b ,  33   a ,  33   b ,  33   c  serve to spray liquid onto the washware which is to be treated as the washware is conveyed through the respective treatment zones  10 ,  11 . 1 ,  11 . 2 ,  12 ,  13  by the conveyor apparatus  2 . The individual spray systems of the treatment zones  10 ,  11 . 1 ,  11 . 2 ,  12 ,  13  ensure that the washware which is to be treated is hosed down both from the top and from the bottom. 
     However, in the conveyor dishwasher  1  schematically illustrated in  FIG. 1 , the final rinse zone  13  not only has downwardly directed upper spray nozzles  33   a  and upwardly directed lower spray nozzles  33   b , but also transversely directed lateral final rinse nozzles  33   c  on either side of the conveyor apparatus  2 . The use of lateral final rinse nozzles  33   c  permits areas of the washware (areas of the tableware) to be sprayed with final rinse liquid in a targeted manner in shadow zones too. The use of lateral final rinse nozzles  33   c  in the final rinse zone  13  has a significant advantage in terms of the final rinse result (effective rinsing-off of detergent residues from surfaces of the tableware in shadow zones too) compared to systems in which only upper and lower final rinse nozzles  33   a ,  33   b  and no transversely directed lateral final rinse nozzles  33   c  are provided in the final rinse zone  13 , specifically when the conveying system is fully loaded, for example with plate-to-plate loading of the dish rack. 
     The postwash or prerinse zone  12 , main wash zones  11 . 1 ,  11 . 2  and prewash zone  10  also have associated tanks (postwash tank  22 , main wash tank  21 . 1 ,  21 . 2 , prewash tank  20 ) for accommodating sprayed liquid and/or for providing liquid for the spray nozzles  30   a ,  30   b ,  31 . 1   a ,  31 . 1   b ,  31 . 2   a ,  31 . 2   b ,  32   a ,  32   b  of the relevant treatment zones  10 ,  11 . 1 ,  11 . 2 ,  12 . 
     As already indicated, final rinse liquid, which comprises fresh water with rinse aid which is added in a metered fashion, is sprayed onto the washware (not illustrated) by means of final rinse nozzles  33   a ,  33   b ,  33   c  which are arranged above and below the conveyor apparatus  2  and on the side in the conveyor dishwasher  1  illustrated in  FIG. 1 . A portion of the sprayed final rinse liquid is conveyed from treatment zone to treatment zone via a cascade system in the opposite direction to the conveying direction T of the washware. The remaining portion of the final rinse liquid sprayed in the final rinse zone  13  is conducted directly to the prewash tank  20  which is associated with the prewash zone  10  via a valve V 1  and a bypass line  6 . 
     In the cascade system, the final rinse liquid sprayed by the final rinse nozzles  33   a ,  33   b ,  33   c  flows from the final rinse zone  13  into the postwash tank  22 , which is associated with the postwash zone  12 , due to the force of gravity. The final rinse liquid sprayed in the final rinse zone  13  and collected by the postwash tank  22  is then delivered to the spray nozzles of the postwash zone  12  (upper and lower postwash nozzles  32   a ,  32   b ) with the aid of a postwash pump  36 . 
     Wash liquid is rinsed off from the washware in the postwash zone  12 . The liquid (postwash liquid) produced in the process flows into the first main wash tank  21 . 1 , which is associated with the first main wash zone  11 . 1 , due to the force of gravity. A discharge element  7 , for example a discharge base or a baffle plate, which conducts the postwash liquid sprayed by the postwash nozzles  32   a ,  32   b  into the main wash tank  21 . 1  is preferably provided for this purpose. According to another embodiment (not illustrated) of the conveyor dishwasher  1 , the outlet element  7  can be dispensed with if the main wash tank  21 . 1  extends as far as beneath the postwash nozzles  32   a ,  32   b  of the postwash zone  12 . 
     The liquid accommodated by the main wash tank  21 . 1  of the first main wash zone  11 . 1  is usually provided with a detergent and sprayed onto the washware by means of the spray nozzles of the first main wash zone  11 . 1  (upper and lower main wash nozzles  31 . 1   a ,  31 . 1   b ) with the aid of a first main wash pump  35 . 1 . The wash liquid which is sprayed by the main wash nozzles  31 . 1   a ,  31 . 1   b  then flows back into the main wash tank  21 . 1  due to the force of gravity. 
     The main wash tank  21 . 1  is fluidically connected to the main wash tank  21 . 2 , which is associated with the second main wash zone  11 . 2 , via an overflow line  9 . 1 . The wash liquid which is sprayed in the first main wash zone  11 . 1  enters the main wash tank  21 . 2  of the second main wash zone  11 . 2  via this overflow line  9 . 1  when there is a sufficient quantity of wash liquid in the main wash tank  21 . 1  of the first main wash zone  11 . 1 . 
     The liquid accommodated by the main wash tank  21 . 1  of the second main wash zone  11 . 2  is sprayed onto the washware by means of the spray nozzles of the second main wash zone  11 . 2  (upper and lower main wash nozzles  31 . 2   a ,  31 . 2   b ) with the aid of a second main wash pump  35 . 2 . The wash liquid which is sprayed by the main wash nozzles  31 . 2   a ,  31 . 2   b  then flows back into the main wash tank  21 . 2  of the second main wash zone  11 . 2  due to the force of gravity. 
     The main wash tank  21 . 2  of the second main wash zone  11 . 2  is fluidically connected to the prewash tank  20  which is associated with the prewash zone  10  via an overflow line  9 . 2 . The wash liquid which is sprayed in the second main wash zone  11 . 2  enters the prewash tank  20  via this overflow line  9 . 2  when there is a sufficient quantity of wash liquid in the main wash tank  21 . 2  of the second main wash zone  11 . 2 . 
     The liquid accommodated in the prewash tank  20  of the prewash zone  10  is then sprayed onto the washware by means of the spray nozzles of the prewash zone  10  (upper and lower prewash nozzles  30   a ,  30   b ) with the aid of a prewash pump  34 , in order to remove coarse particles of dirt from the washware. The wash liquid which is sprayed by the prewash nozzles  30   a ,  30   b  then flows back into the prewash tank  20  due to the force of gravity. 
     The prewash tank  20  is provided with an overflow line  8  which is used to feed the excess quantity of liquid to a waste water system if a specific liquid level in the prewash tank  20  is exceeded. 
     As already indicated, the liquid which is sprayed in the main wash zones  11 . 1 ,  11 . 2  and in the prewash zone  10  preferably contains detergent which is added in a metered fashion with the aid of a detergent metering apparatus (not shown in the drawings), for example, to the liquid which is accommodated in the main wash tank  21 . 1  of the first main wash zone  11 . 1 . 
     As already mentioned, the final rinse zone  13  is followed by the drying zone  14  in the conveying direction T. In the drying zone  14 , the washware is dried using dry and heated air in order to blow off and/or dry up the moisture on the washware. In order to keep the moisture content of the air in a range which is expedient for drying, it is feasible, for example, to supply external room air to the drying zone  14  via an opening, for example through the outlet opening for the washware. 
     The warm and moisture-laden air in the drying zone  14  is then drawn-off from the drying zone  14  via a further opening, for example with the aid of a fan  15 . It is advantageous here if the exhaust-air stream from the drying zone  14  passes a heat recovery device  16  in which, for example, a condenser can be provided. The heat recovery device  16  serves to recover at least some of the thermal energy contained in the exhaust air. This recovered thermal energy can be used, for example, to heat the liquid which is to be sprayed in the final rinse zone  13 . 
     If, before initial starting of the conveyor dishwasher  1 , the tanks (prewash tank  20 , main wash tank  21 . 1 ,  21 . 2 , postwash tank  22 ) which are associated with the treatment zones  10 ,  11 . 1 ,  11 . 2 ,  12  are empty or insufficiently filled, the tanks first have to be filled via a fresh water line  18  and/or by spraying final rinse liquid in the final rinse zone  13 . The fresh water line  18  can be connected to a fresh water supply system via an actuable valve V 3 . The quantity of wash liquid available in the main wash zones  11 . 1 ,  11 . 2  and in the prewash zone  10  can in each case be monitored and signalled to a control device  40  with the aid of a level sensor which is provided in the main wash tank  21 . 1 ,  21 . 2  of the first and/or second main wash zone  11 . 1 ,  11 . 2  and with the aid of a level sensor which is provided in the prewash tank  20 . 
     The final rinse zone  13  can—as illustrated in FIG.  1 —have an associated fresh water container  23  for temporarily storing at least a portion of the fresh water which is provided for final rinsing purposes. The fresh water container  23  is firstly provided with a fresh water connection which can be connected to a fresh water supply system via an actuable fresh water feed valve V 2 . Secondly, the fresh water container  23  is connected to the intake end of a final rinse pump  37 . 
     The delivery end of the final rinse pump  37  is connected to the upstream end region  47  of a main line system  44  by means of which fresh water is conveyed from the fresh water container  23  to the final rinse nozzles  33   a ,  33   b ,  33   c  when the final rinse pump  37  is operated. Specifically, the main line system  44  connects the delivery end of the final rinse pump  37  to a water heater  17  (boiler). In this case, the main line system  44  is designed in such a way that the liquid which is supplied from the final rinse pump  37  to the final rinse nozzles  33   a ,  33   b ,  33   c  first passes the heat recovery device  16  before reaching the water heater  17 . In this way, it is possible to use at least some of the thermal energy of the exhaust air which is discharged to the drying zone  14  to heat up the liquid which is supplied to the spray nozzles  33   a ,  33   b ,  33   c  via the main line system  44 . 
     Various embodiments of conveyor apparatuses  2  for conveying washware through the conveyor dishwasher  1  which is schematically illustrated in  FIG. 1  will be described below with reference to the illustrations in  FIGS. 2   a  to  4   b.    
     Specifically,  FIGS. 2   a  and  2   b  schematically show a region of a first exemplary embodiment of a conveyor apparatus  2  which is suitable for use in a conveyor dishwasher  1  according to the illustration in  FIG. 1 . In this case,  FIG. 2   a  shows a plan view of the machine outlet-end region of the conveyor apparatus  2 , while  FIG. 2   b  illustrates the corresponding cross-sectional view. 
     Accordingly, the conveyor apparatus  2  which is illustrated in  FIGS. 2   a  and  2   b  has a first conveyor belt  50  for trays or tray-like washware  100  and also a second conveyor belt  51 , which runs parallel to the first conveyor belt  50 , for other washware, in particular plates  101 , bowls  102  and/or cutlery  103 . The first conveyor belt  50  is relatively narrow in comparison with the second conveyor belt  51 , and therefore a tray or tray-like item  100  of washware can be held by the first conveyor belt  50  only in a state in which it is placed on edge and is oriented parallel to the conveying direction T. The orientation of the washware  100  which is to be held by the first conveyor belt  50  parallel to the direction in which the first conveyor belt  50  runs results in minimal utilization of the surface area of the total belt surface area. In other words, the first conveyor belt  50  has a width which is reduced in such a way that only a minimal surface area of the total belt surface area is occupied by the first conveyor belt  50 , this specifically permitting trays or tray-like washware  100  to be placed in position when this washware  100  is in a state in which it is placed on edge and is oriented parallel to the conveying direction T. 
     This means that it is possible for the second conveyor belt  51 , as before, to have a sufficient width in order to continue to be able to be used almost without restriction for conveying other washware, in particular plates  101 , bowls  102  and/or cutlery  103 , through the individual treatment zones of the conveyor dishwasher  1 . Therefore, for example, racks of glasses or GN containers can, as before, also be placed on the second conveyor belt  51  next to the tray or tray-like item  100  of washware which is held on the first conveyor belt  50 . 
     In the embodiment which is illustrated in  FIGS. 2   a  and  2   b , a tray  100  and two plates  101  are arranged next to one another merely as an example, with the tray  100  being disposed on the first conveyor belt  50  of the conveyor apparatus  2  and the plates  101  being disposed on the second conveyor belt  51  of the conveyor apparatus  2 . In this embodiment, the plates  101  are retained on the second conveyor belt  51  with the aid of compartments, with these compartments being formed by supporting fingers  63  which are provided on the second conveyor belt  51 . 
     As already indicated, the second conveyor belt  51  has—despite the provision of a first conveyor belt  50  which runs parallel to the second conveyor belt  51 —a sufficient width to also be able to accommodate conventional racks of glasses etc. This is achieved without the conveyor dishwasher  1  having to have a conveyor apparatus  2  which is wider overall. 
     The solution according to the invention therefore allows both trays or tray-like washware  100  and other washware, in particular plates  101 , bowls  102  and/or cutlery  103 , to be cleaned at the same time. Therefore, cleaning processes which proceed in parallel can be implemented on both conveyor belts  50 ,  51 , this ultimately reducing the total length of the washing and rinsing process in a commercial scullery. This in turn reduces the working time of the dishwashing personnel and leads to a reduction in the consumption of resources by the conveyor dishwasher  1 . 
     As can be seen in the illustration in  FIG. 2   b  in particular, the first conveyor belt  50  is designed to hold trays or tray-like washware  100  in the exemplary embodiment of the conveyor apparatus  2 , with this washware being supported on the first conveyor belt surface by means of a border or edge region  100 ′. In order to securely retain the tray-like washware  100  which is held on the first conveyor belt  50  and is placed on edge, it is advantageous, in particular, if a guide which is associated with the first conveyor belt  50  is provided. This guide preferably serves not only to retain the washware  100  on the first conveyor belt  50 , but also to guide the washware  100  which is held on the first conveyor belt  50  as it is conveyed through the respective treatment zones of the conveyor dishwasher  1 . 
     In the embodiment of the conveyor apparatus  2  which is illustrated in  FIGS. 2   a  and  2   b , a guide of this kind is implemented in the form of a lower guide groove at one end and in the form of an upper guide rail at the other end. The illustration in  FIG. 2   b  shows, in particular, that a guide groove  60 , which is formed in the first conveyor belt  50  and runs in the longitudinal direction of the first conveyor belt  50 , is designed to guide and retain the tray-like item  100  of washware which is held on the first conveyor belt  50 . This guide groove  60  serves to hold a border or edge region  100 ′ of a tray or tray-like item  100  of washware which is placed on the first conveyor belt  50 . 
     In addition to the (lower) guide groove,  60 , an upper guide element  61 , which is situated opposite the first conveyor belt  50  and is implemented as a guide rail in this case, is used in the embodiment which is illustrated in  FIGS. 2   a  and  2   b . As indicated in  FIG. 2   b , this guide element  61  is designed to hold a region  100 ″ of a tray or tray-like item  100  of washware which is placed on the first conveyor belt  50  and to guide the washware  100  as it is conveyed through the individual treatment zones of the conveyor dishwasher  1 . It is clear that the washware  100  which is placed on edge on the first conveyor belt is securely retained on the first conveyor belt  50  on account of the provision of the lower guide groove  60  and of the upper guide element  61 . 
     As can be seen in the illustration in  FIG. 2   b , the upper guide element  61  is preferably designed to hold a region  100 ″ of the tray or tray-like item  100  of washware which is placed on the first conveyor belt  50 , which region  100 ″ is situated opposite the border or edge region  100 ′ by means of which the tray or tray-like item  100  of washware is supported on the first conveyor belt  50 . 
     In order to be able to hold trays or tray-like washware with different dimensions on the first conveyor belt  50 , it is advantageous if the upper guide element  61  is adjustable in the vertical direction. In this way, the upper guide element  61 , in a manner which is simple to implement, can be matched to the height of a tray or tray-like item  100  of washware which is to be held by the first conveyor belt  50  and is placed on edge. Accordingly, the first conveyor belt  50  is suitable firstly for holding trays  100  which are supported on the first conveyor belt  50  by means of their longitudinal side edge, and secondly for holding trays  100  which are supported on the first conveyor belt  50  by means of their transverse side edge. Therefore, the first conveyor belt  50  can be used flexibly for various applications. 
     The illustration in  FIG. 2   b , in particular, shows that a belt guide  62  which is associated with the first conveyor belt  5  is provided in the exemplary embodiment of the conveyor apparatus  2  which is schematically shown in said illustration. A belt guide  62  of this kind is advantageous, in particular, when—as in the embodiment which is illustrated in  FIGS. 2   a  and  2   b —the first conveyor belt  50  is in the form of an endless drive belt. The provision of a belt guide  62  of this kind ensures, in a simple to implement yet effective manner, that the first conveyor belt  50  always runs parallel to the second conveyor belt  51 . Furthermore, it has proven advantageous if the first conveyor belt  50  is in the form of a flat belt, a V-belt, a toothed belt or a round belt, in order to provide additional guidance of the first conveyor belt  50 . 
     As indicated in  FIG. 2   b , the belt guide  62  which is associated with the first conveyor belt  50  can be fixed, for example, to belt rod shafts  55  of the second conveyor belt  51 , as a result of which the conveyor apparatus  2  is provided with a compact design. However, it goes without saying that other embodiments for fixing the belt guide  62  are feasible. 
     As already cited, a guide groove  60 , which is formed in the first conveyor belt  50  and runs in the longitudinal direction of the first conveyor belt  50 , is provided in the embodiment which is illustrated in  FIGS. 2   a  and  2   b , it being possible for a border or edge region  100 ′ of a tray or tray-like item  100  of washware which is placed on the first conveyor belt  50  to be held in the guide groove in order to guide the washware  100  which is placed on edge on the first conveyor belt  50  as it is conveyed through the respective treatment zones of the conveyor dishwasher  1 . However, instead of a guide groove  60  of this kind, it is also feasible for the belt guide  62  to be used to not only guide the first conveyor belt  50 , but also the washware  100 , which is placed on the first conveyor belt  50 , as it is conveyed through the respective treatment zones of the conveyor dishwasher  1 . If—as illustrated in  FIG. 2   b —the belt guide  62  is in the form of a vertically oriented guide face, this vertically oriented guide face can, at the same time, serve as a stop face for a border or edge region  100 ′ of a tray or tray-like item  100  of washware which is held on the first conveyor belt  50  and is placed on edge. Although not illustrated in the drawings, it is therefore feasible for the border or edge region  100 ′ of the tray or tray-like item  100  of washware which is held on the first conveyor belt  50  and is placed on edge to be supported on the vertically oriented guide face of the belt guide  62 , this enabling the washware  100  which is held on the first conveyor belt  50  to be guided through the respective treatment zones of the conveyor dishwasher  1 . 
     In one possible implementation, the upper guide element  61  is in the form of a guide rail. This guide rail preferably runs in such a way that a tray or tray-like item  100  of washware, which is held on the first conveyor belt  50 , is transferred from its state in which it is placed on edge to its horizontally oriented normal state and then destacked at the outlet of the conveyor dishwasher  1 , that is to say downstream of the at least one final rinse zone  13  as seen in the conveying direction T. In this embodiment, the tray or tray-like washware  100  which was originally held on the first conveyor belt  50  is therefore automatically destacked at the machine outlet, this enabling a further reduction in operating personnel at the machine outlet. 
     It is preferred, in principle, if the first conveyor belt  50 , which is provided for conveying trays or tray-like washware  100 , has a higher conveying speed in comparison to the second conveyor belt  51  which is provided for other washware. The increase in the conveying speed enables the trays or the tray-like washware  100  to be placed in position, without delay, at the time at which all the items of cutlery and tableware are removed from the tray. Therefore, the trays  100  are not deposited in a stack after the items of tableware and cutlery are removed, but rather are placed directly into the first conveyor belt  50 . Therefore, a second working step with the respective tray  100  is dispensed with in this embodiment. 
     In a preferred implementation of the last-mentioned embodiment, provision is made for a common drive apparatus to be provided for the first and second conveyor belts  50 ,  51 , the first and second conveyor belts  50 ,  51  being jointly driven by means of the common drive apparatus. The provision of a common drive apparatus simplifies the overall design of the conveyor dishwasher. 
     In order to be able to implement different conveying speeds in a common drive apparatus for the first and second conveyor belts  50 ,  51 , it is feasible for the first conveyor belt  50  to be connected to the common drive apparatus by means of a first drive shaft which is associated with the first conveyor belt  50  and a first gear mechanism apparatus which is associated with the first conveyor belt  50 , while the second conveyor belt  51  is connected to the common drive apparatus by means of a second drive shaft which is associated with the second conveyor belt  51  and a second gear mechanism apparatus which is associated with the second conveyor belt  51 . The respective transmission ratio of the first and the second gear mechanism apparatus is preferably selected in such a way that the conveying speed at which an item  100  of washware which is held by the first conveyor belt  50  is conveyed through the respective treatment zones of the conveyor dishwasher  1  is higher than the conveying speed at which an item  100  of washware  101 ,  102 ,  103  which is held by the second conveyor belt  51  is conveyed through the respective treatment zones of the conveyor dishwasher  1 . 
     However, as an alternative to this, it goes without saying that it is also possible to provide an associated drive apparatus for each conveyor belt  50 ,  51  for the purpose of driving the corresponding conveyor belt  50 ,  51  in such a way that an item of washware which is held by the respective conveyor belt  50 ,  51  is conveyed through the respective treatment zones of the conveyor dishwasher  1  at a conveying speed which is or can be set individually for the respective conveyor belt  50 ,  51 . 
     A further embodiment of the solution according to the invention will be described below with reference to the illustrations in  FIGS. 3   a  and  3   b . Specifically, these figures schematically show the machine outlet-end region of a second exemplary embodiment of a conveyor apparatus  2  which is suitable for use in a conveyor dishwasher  1  according to the illustration in  FIG. 1 . 
     The embodiment of the conveyor apparatus  2  which is illustrated in  FIGS. 3   a  and  3   b  differs from the embodiment which is described above with reference to the illustrations in  FIGS. 2   a  and  2   b  in that, in addition to the first and second conveyor belts  50 ,  51 , a further conveyor belt  52  is provided. In the embodiment which is illustrated in  FIGS. 3   a  and  3   b , this further conveyor belt  52  runs parallel to the first and second conveyor belts  50 ,  51  and serves to hold cutlery or cutlery-like washware  103 . In this case, provision is preferably made for the further conveyor belt  52  to run directly next to the first conveyor belt  50  and between the first and second conveyor belts  50 ,  51 . 
     Like the first conveyor belt  50 , the further conveyor belt  52  also has a reduced width in comparison to the total belt surface area, and in particular in comparison to the width of the second conveyor belt  51 , in order to ensure minimal utilization of the surface area of the total belt surface area. In other words, despite the provision of the first conveyor belt  50  and of the further conveyor belt  52 , the second conveyor belt  51  is suitable, as before, for holding, for example, racks of glasses or two items of washware which are arranged next to one another, for example a plate  101  and a bowl  102 . 
     It is likewise preferred if, after passing through the conveyor dishwasher  1 , the cutlery  103  which is held by the further conveyor belt  52  falls into a container which is provided at the machine outlet, this enabling a further reduction in operating personnel at the machine outlet. In particular, this embodiment enables handling actions for cutlery to be completely dispensed with both at the machine inlet (dirty end of the conveyor dishwasher  1 ) and at the machine outlet (clean end of the conveyor dishwasher  1 ). 
     The concept of the plurality of conveyor belts which run in parallel can be extended virtually as desired in this sense and various combinations of conveyor belts which are specially provided for specific types of washware are possible. In addition to the above-described solutions in which up to three conveyor belts  50 ,  51 ,  52  which run in parallel are provided, it is feasible, in particular, to provide special conveyor lanes for plates  101  and bowls  102  since automatic destacking systems for these types of washware are already known from semi- and fully automatic technology. 
     Therefore, with regard to a conveyor dishwasher  1  which operates as efficiently as possible, it is advantageous if, in addition to the first conveyor belt  50  which is specially designed for holding trays or tray-like washware  100 , and in addition to the further conveyor belt  52  which is specially designed for holding cutlery  103 , further conveyor belts or conveyor belt lanes which are designed in respect of a special type of washware are provided. 
     In this connection, reference is made to the embodiment which is illustrated in  FIGS. 4   a  and  4   b . The conveyor apparatus  2  which is partially illustrated in these figures corresponds substantially to the embodiment which is described above with reference to the illustration in  FIGS. 3   a  and  3   b , but with the second conveyor belt  51  now having been subdivided into a conveyor lane for the type of washware “plates” and a further conveyor lane for the type of washware “bowls”. In other words, in the embodiment which is illustrated in  FIGS. 4   a  and  4   b , the second conveyor belt  51  is subdivided into two conveyor belts  51   a ,  51   b  which run parallel to one another. Although not illustrated in the drawings, each conveyor belt  51   a ,  51   b  has an automatic stacking or destacking device at the machine inlet (dirty end of the conveyor dishwasher  1 ) and/or at the machine outlet (clean end of the conveyor dishwasher  1 ) in order to stack plates  101  into or to destack plates  101  from the conveyor belt  51   a  and in order to stack bowls  102  into the conveyor belt  51   b  or to destack bowls  102  from the conveyor belt  51   b.    
     This subdivision of the second conveyor belt  51  into special lanes and automated stacking and destacking increase the degree of automation of the conveyor dishwasher  1 , and therefore working time can be saved both at the clean end and at the dirty end of the conveyor dishwasher  1 . The dishwashing process therefore runs more efficiently and its total length is reduced, and therefore, in addition to working time, resources can also be saved. 
     It is feasible for a common drive apparatus to be provided for the second conveyor belt  51  and the at least one further conveyor belt  52 , or for the conveyor belt  51  which is subdivided into two conveyor belts  51   a ,  51   b  and the at least one further conveyor belt  52 , the corresponding conveyor belts  51 ,  51   a ,  51   b ,  52  being jointly driven by means of the common drive apparatus. The conveying speed of each conveyor belt  50 ,  51 ,  51   a ,  51   b ,  52  can preferably be set individually. 
     The illustration in  FIG. 4   b  shows that the respective upper faces of the conveyor belts  50 ,  51   a ,  51   b  and  52  of the conveyor apparatus  2  lie in a common horizontal plane. This allows washware to also be held across a plurality of conveyor belts  50 ,  51   a ,  51   b  and  52 , that is to say by a plurality of conveyor belts  50 ,  51   a ,  51   b  and  52  at the same time. 
     It should be noted that the invention is not restricted to the exemplary embodiments which are illustrated above with reference to the drawings, but rather can be gathered by examining all the individual features disclosed in these exemplary embodiments together.