Patent Publication Number: US-2020281436-A1

Title: Dish washing apparatus and dish drying apprartus

Description:
TECHNICAL FIELD 
     The present disclosure relates to dish washing and drying apparatus. More specifically it relates to conveyer type systems in which dishes are moved through a dishwashing system. 
     BACKGROUND 
     Commercial dishwashers are used in the food industry to clean a large volume of used dishes every day. They are typically installed in restaurants, canteens, and hotels. 
     There are several different categories of commercial dishwasher known today, and they are generally categorized by their washing capacity and/or other specifications. The capacities of commercial dishwashers can range from a few hundred dishes per hour to twenty thousand dishes or more per hour. It is common practice for the type of dishwashing apparatus to be selected according to the required washing rate. The other factors that may be considered before purchasing a commercial dishwasher include water and energy efficiency, as well as the operating cost and/or the use of green technologies. Recently, water scarcity and increasing operation costs have driven the commercial dishwasher industry to develop better performing dishwashing machines. 
     Besides washing capacities, commercial dishwashers can also be categorized into different types such as: conveyor type (e.g. freight-type) dishwashers for serving extremely high volume of dishes at an extremely high washing rate, rack-type dishwashers for serving a medium volume of dishes at a medium washing rate, and hood-type (over-the-counter) dishwashers for serving low volume of dishes at a low washing rate. There are also hybrid dishwasher types in between, the functions and working principles are generally the same. 
     A conveyor type dishwasher is usually installed for extreme high volume washing rate. This type of dishwasher has multiple chambers and treatment zones. The conveyor system with tooth-like structures for holding dishes moves at a constant speed, thereby moving the dishes in a forward direction passing through individual chambers and treatment zones. This type of dishwasher will wash and handle between ten to twenty thousand or more dishes per hour. The length of this type of dishwasher can vary from twenty to forty meters or more, and the width can vary from one to two or more meters. A small conveyor type dishwasher will wash and handle between three to ten thousand dishes. The length can vary from ten to twenty-five meters, and the width can vary from one to two or more meters. Due to the size of conveyor type dishwashers, they are usually deployed in large food catering businesses such as large hotels, and hospitals whereby there are centralized washing facility within the building. 
     Rack type dishwashers handle between two to five hundred racks per hour. Used dishes are loaded onto a rack and subsequently the rack is pushed into a machine feeder that drives the rack through the dishwasher and past multiple treatment zones. Each specially built rack holds between ten to twenty dishes. The length of this type of dishwasher varies between two to ten meters, and the width is about a meter wide. Rack type dishwashers are usually deployed in large restaurants, middle-sized hotels and school canteens. 
     Both conveyor and rack types of dishwashers can be custom-built to specific requirements. For example, extra chambers for additional rinsing, or an elongated conveyor belt to transport the racks and/or dishes away from the dishwasher to a clean collection zone may be added to the conventional dishwasher setup. 
     Hood-type dishwashers can handle between forty to one hundred racks per hour. The length of this type of dishwasher is usually less than a meter long. However, if desired, a single bowl stainless steel sink and/or a stainless steel table top may be installed for the pre and post washing process. This type of dishwasher is commonly deployed in small restaurants, or in places where space is at a premium within a kitchen setting. 
     Manual dishwashing requires a labourer to clean the dishes. The process is time-consuming, manually repetitive and monotonous. Although manual washing does not require electrical energy, water usage is usually high and dependent on the washing style that varies from person to person. The disadvantages of manual washing include the slow laborious process, high volume of man hours required, water wastage, and inconsistencies in quality and cleanliness of the cleaning, extensive manual washing also poses health risks to the labourer that washes the dishes as they may be come into contact with the detergent used. These disadvantages can be overcome by using automatic dishwashers. 
     Automatic dishwashers generally have multiple functions, as well as different zones and programs that are all integrated and work systemically within a standard dishwashing unit. If additional washing volume is needed, the units may have a function to alter the pre-set washing time such as by increasing or decreasing the washing speed. The program is designed to operate on a pre-set transportation routine to move the dishes through the different zones such as the prewash zone, main wash zone, post-wash zone, final-rinse zone, drying zone and collection zone. Each zone may have an associated tank in which sprayed liquid and an array of spray nozzles that are used to perform a pre-set function. 
     Another important factor when using commercial dishwashers is the operating cost. A newer model has cost effective operation system build into the features. Operating cost saving can be achieved by installing different type of sensor across the dishwasher. These sensors, ranged from temperature sensor, pressure and flow sensor or dish detecting sensor. These sensors provide inputs to a CPU unit to control, monitor and regulate the resources needed to run the dishwasher. Resources that can be optimized include water, electricity and detergent. 
     The conveyor and rack type dishwashers both require large installation and working space. The hood type dishwasher can achieve good economies of scale but it still requires a large workspace. 
     Within some types of dishwashing apparatus, a rubber material curtain may be installed as a water barrier between each treatment zones to contain the water used in each zone when a dish moves from a treatment zone to the next. These curtains are short, equally-spaced vertical cut slips that have insulation and a low friction coefficient to contain the heat within the designated space to reduce energy lost when the dish move to the next zone. 
     These zone transitions are difficult to optimize in terms of space usage. For example, as the dish progress from one heated water treatment zone to the next treatment zone, it faces three constraints. Firstly, the water outlet is positioned too near the entrance or extremely close to the next treatment zone, it may result in unwanted water spill over to the next zone. Usually, each treatment zone has its own collecting water tank. Therefore unwanted water spill in between the zone increases the workload of the water filtering system. Secondly, as the dish passes through, it has to touch the rubber material curtain, pushing it upward and along the distance travel. Once the rubber is pushed upward, there is an unwanted opening space, or gap. This opening space creates unwanted energy lose or allow the treatment water to pass through to the next zone. Most importantly, at the last treatment zone where heated air is blown downward to dry the wet dishes, the unwanted open space allows sudden hot air to escape the treatment zone. This is extremely dangerous for a labourer who collects the dish near the last treatment zone, which may result in burns from the hot air that escapes from the last treatment zone. Lastly, after the rubber material curtain touches the topside of the dish as it passes from one zone to the next, the rubber material curtain naturally drops down and touches the next dish. The residue on the rubber material curtain may be propelled from this action to various directions. Hence, the current dishwashing design requires a reasonable transition space in between the treatment zones. 
     A hood-type dishwasher machine has the advantage of containing the washing cycle within a prescribed space because the racks that hold the dishes do not move. Water is dispensed from a revolving mechanism, which is positioned at the top and at the bottom of the dishwasher machine. In this design, no transition space is needed as there is no spillage from one zone to the next. The machine just needs to run through the washing program cycle. However, this type of dishwasher usually does not include a high temperature drying cycle. This is not a cost effective solution to dry the dishes as the space within the dishwasher is always at a high humidity level. Hence, drying of the dishes is usually performed by manually wiping away of the remaining water residue. 
     Automatic dishwashers have improved the dish washing process, but the loading of used dishes and unloading of washed dishes still remains a manual labour intensive process. The washing capacity can only be as effective as the number dishes loaded and dispensed onto the conveyor or onto the rack-type dishwasher. Preparation and coordination are needed between the person who is loading the dish and the person stacking the dishes. It is common to see that there are at least two rows of personnel standing beside the entrance and exit of an automatic dishwasher to load and unload the dishes at a very fast pace. As the conveyor is moving at a constant speed, the handler has to decide the spacing between the dishes, and the orientation that the dishes are to face before and during the loading. This has to be performed in spilt second decision. Dishes loaded with wrong orientation may result in an unclean surface at the end of the washing process. In order to prevent this type of mistake, the loader has to be fully aware and concentrate on the task ahead. For the loader, if another cycle of the load is complete and if one of the dishes is loaded at the wrong orientation, the loader has to unload the dish and reload it to the desired orientation. By doing so, the loader may miss the next cycle of dish loading action. 
     If the dishes are made of a fragile material like porcelain or glass, the job of loading and unloading the dishes is more delicate as the dishes are more fragile. Any breakage of a dish will usually result in a shutdown of the dishwasher apparatus. Hence, the dishwashing capacity has a correlation with the workspace and manpower designated around the dishwasher. 
     Another less discussed issue for dishwashing apparatuses is the noise pollution caused during the loading and unloading of dishes. As the dishes collide against each other during loading and unloading, an unpleasant sound is generated. This could be one of the reasons that large volume dishwashers are not installed near or inside kitchens. 
     The hood-type dishwasher does not have the issues related to loading and unloading the dishes at a very fast pace. However, the pre- and post-preparation process is significantly slower. This type of dishwasher is relatively smaller than the other types of dishwashers discussed, but the space that is needed and used for the pre- and post-preparation processes is sometime more than the space required for the other types of dishwashers. Typically, the dishes have to be pre-rinsed before loading onto the rack. Then only when the rack is full then is it economical for the rack of dishes to be wash. Normally, there is at least sufficient space for three racks to be worked on prior to entering the dishwashing apparatus. After the washing cycle, a labourer has to dry and pack the dishes, and this requires at least another three to four racking spaces after the dishwashing apparatus. Hence, hood-type dishwashers may require a large working area that is equivalent to that of a mini size rack-type dishwasher. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present disclosure, a dishwashing apparatus comprises: a spray nozzle configured to spray a liquid onto a target zone; a first rod; a second rod; and a third rod; the first rod, second rod and third rod each having a screw thread on an outer surface and each being rotatable about a respective longitudinal axis; the first rod, second rod and third rod being arranged in a parallel configuration, at equal distances from a central axis, wherein the separation of each of the first rod, second rod and third rod from the central axis is configured or configurable to receive a plurality of dishes such that the screw thread on each of the rods engages with the circular rim or lip of the dishes and when the rods are rotated about their respective axes, the dishes are caused to move relative to the spray nozzle in the direction of the central axis and rotate as they pass through the target zone. 
     According to a second aspect of the present disclosure, a dish drying apparatus for drying dishes having a circular rim or lip is disclosed. The apparatus comprises: an air outlet configured to direct air onto a target zone; a first rod; a second rod; and a third rod; the first rod, second rod and third rod each having a screw thread on an outer surface and each being rotatable about a respective longitudinal axis; the first rod, second rod and third rod being arranged in a parallel configuration, at equal distances from a central axis, wherein the separation of each of the first rod, second rod and third rod from the central axis is configured or configurable to receive a plurality of dishes such that the screw thread on each of the rods engages with the circular rim or lip of the dishes and when the rods are rotated about their respective axes, the dishes are caused to move relative to the air outlet in the direction of the central axis and rotate as they pass through the target zone. 
     An advantage of embodiments of the invention is that when dishes are engaged by the three rods, they are held in three points. This means they cannot be moved by the liquid from the spray nozzle or the airflow from air outlet. Thus embodiments of the present invention provide for dish drying apparatus in which high velocity airflows can be used for drying. 
     The positions of the rods may be adjustable to allow the apparatus to accommodate different sized dishes. 
     According to a third aspect of the present invention a dishwashing system is provided which is configured to subject dishes to a plurality of treatments, each of the treatments being applied in a respective treatment zone, the dishwashing system comprising a dishwashing and dish drying apparatus arranged to move dishes through each of the treatment zones. The central axis of the dishwashing apparatus may be arranged at an angle to the horizontal direction such that the dishes raise in vertical direction as the dishes progress along the screw thread in the direction of the central axis. 
     The system may comprise a baffle device arranged to reduce water flow between a respective pair of treatment zones. In an embodiment, one of the treatment zones comprises a drying zone having a drying apparatus the drying zone comprises a baffle device configured to direct airflow from the air outlet onto the target zone. The baffle device may comprise a plurality of plates arranged to slide relative each other the plurality of plates arranged to provide an aperture having a size which is adjustable depending on a relative positioning of first, second, and third. 
     The position adjustment system may be configured to control the relative positioning of the plurality of plates. 
     A dishwashing system may comprise a plurality of dishwashing apparatuses. These may be fixed or adjustable to accommodate different sizes of dish. 
     The dishwashing system may further comprise a loading system a loading system, for loading dishes onto the dishwasher apparatus. The loading may comprise a pivotally movable arm or a robotic arm or a pair of curved guides having grooves configured to receive the rim or lip of a dish and transfer the dish from a horizontal orientation to a position in which the dish is in contact with the first, second and third rods. 
     The dishwashing system may further comprise an unloading system, for unloading dishes from the dishwasher apparatus. The unloading system may comprise a knockdown device or a cooperative robotic arm. 
     The dishes may be stored on trolleys which store dishes sorted according to a lip or rim diameter. 
     In order to allow non-circular dishes to be washed in the system a holder configured to hold dishes may be provided which comprises a circular ring configured to engage with the screw thread. 
     In order to allow items such as cutlery and utensils to be washed, a cage assembly comprising a plurality of rings configured to engage with the screw thread. May be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, embodiments of the present invention will be described as non-limiting examples with reference to the accompanying drawings in which: 
         FIG. 1  shows a dishwashing apparatus according to an embodiment of the present invention; 
         FIGS. 2A and 2B  show perspective views of a dishwashing system according to an embodiment of the present invention; 
         FIG. 2C  is a top down view of the dishwashing system shown in  FIGS. 2A and 2B ; 
         FIG. 3A  is a perspective view of a position adjustment system of the dishwashing apparatus according to an embodiment of the present invention; 
         FIG. 3B  is a perspective view of the dishwashing apparatus and position adjustment system separated into different zones by baffles according to an embodiment of the present invention; 
         FIG. 4A  shows a perspective view of the loading end of the dishwasher assembly according to an embodiment of the present invention; 
         FIG. 4B  shows an expanded view of a rod engaging with the circular rim of lip of a dish; 
         FIG. 4C  shows a perspective view of the leading end of a rod according to an embodiment of the present invention; 
         FIG. 4D  shows an expanded view of a rod engaging with the circular rim of lip of a dish; 
         FIG. 5  shows a cross sectional view of the varying gape of the dishwashing apparatus according to an embodiment of the present invention; 
         FIG. 6  shows a cross sectional view of the baffles in dishwashing system according to an embodiment of the present invention; 
         FIGS. 7A, 7B, and 7C  show loading of dishes of different respective sizes onto a dishwashing apparatus according to an embodiment of the present invention; 
         FIGS. 8A to 8D  show a cross sectional views of drum motor assembly inserted within one of the three rods of the dishwasher apparatus according to an embodiment of the present invention; 
         FIGS. 9A and 9B  show a perspective and a side view of the loading end of the dishwashing apparatus according to an embodiment of the present invention; 
         FIGS. 10A and 10B  respectively show a perspective view and a side view of the unloading end of a dishwashing system according to an embodiment of the present invention; 
         FIGS. 10C and 10D  show views of a collaborative unloading arm retrieving a dish from the unloading end of a dishwashing system according to an embodiment of the present invention; 
         FIGS. 11A and 11B  show a perspective view and a top view of a compact dishwashing system according to an embodiment of the present invention; 
         FIGS. 12A to 12D  show details of a dish lifting mechanism of a compact loading unit according to an embodiment of the present invention; 
         FIGS. 13A to 13E  show views of a dish loading arm system according to an embodiment of the present invention; 
         FIGS. 14A to 14D  show views of a dish unloading system according to an embodiment of the present invention; 
         FIG. 15  shows a trolley for use in a dishwashing system according to an embodiment of the present invention; 
         FIG. 16  shows various trolleys for use in a dishwashing system according to an embodiment of the present invention; 
         FIGS. 17A to 17C  show details of a dish lifting mechanism of a dish cart assembly and movement of a dish by a robotic arm in a system according to an embodiment of the present invention unit according to an embodiment of the present invention; 
         FIG. 18  shows a cage assembly for use in a dishwashing system according to an embodiment of the present invention; 
         FIGS. 19A to 19C  show dish holder devices for use in a dishwashing system according to an embodiment of the present invention; 
         FIG. 20  is a block diagram showing the control system of a dishwashing system according to an embodiment of the present invention; and 
         FIGS. 21A to 21C  show dishwashing apparatus according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a dishwashing apparatus according to an embodiment of the present invention. The dishwashing apparatus  10  is configured for washing dishes  30  having a circular rim or lip  32 . The dishwashing apparatus  10  comprises a spray nozzle  12  arranged to spray a liquid such as water or a water detergent mix onto a target zone. The dishwashing apparatus  10  further comprises a first rod  14 , a second rod  16 , and a third rod  18 . The first rod  14 , second rod  16 , and the third rod  18  are each provided with a screw thread  20  on an outer surface. Each rod is rotatable about a respective longitudinal axis. The first rod  14 , second rod  16 , and the third rod  18  are arranged in a parallel configuration, at equal distances from a central axis. The first rod  14 , second rod  16 , and the third rod  18  are arranged relative to the central to receive the dishes  30  such that the screw thread  20  on each of the rods  14 ,  16 , and  18  engages with the circular rim or lip  32 . When the first rod  14 , second rod  16 , and the third rod  18  are rotated about their respective axes, the dishes are caused to move relative to the spray nozzle in the direction of the central axis and rotate as the pass through the target zone. In some embodiments, the positions of the three rods are adjustable to accommodate different sizes of dishes. 
     The dishwashing apparatus  10  is designed to provide efficient cleaning of dishes with a circular rim and lip. In use, each dish with its circular rim and lip engages with the screw thread on the three rods and when the rods rotate, the dish is conveyed in the direction of the central axis. Additionally, the dishes also rotate around the central axis. Thus, as the dishes pass the spray nozzle, the rotation of the dishes results in the target zone of the spray nozzle moving around the dishes. Thus, a large area of the dish is spray cleaned as it passes through the target zone. Multiple spray nozzles may be used with the dishwashing apparatus to spray liquid onto multiple zones through which the dishes are conveyed resulting in highly targeted and high precision cleaning of the dishes. 
       FIGS. 2A and 2B  show a perspective views of a dishwashing system according to an embodiment of the present invention which comprises a dishwashing apparatus as described above with reference to  FIG. 1 .  FIG. 2A  shows the internal components of the dishwashing system and  FIG. 2B  shows an exterior view. The dishwasher system  100  comprises a support frame that may be divided into a lower portion  101   a  and an upper portion  101   b . The lower portion  101   a  supports the operational components of the dishwashing system such as a water holding tank  106 , a water pump  104 , a filtration system  103 , as well as a filter control unit  105  and a water heater. The upper portion  101   b  supports the dishwashing apparatus  10  as described above in relation to  FIG. 1 . Additionally, the upper portion  109  may also support a drying unit  107 , a pickup conveyor system  500 , and a control interface  102 . Affixed to the support frame of the dishwashing system are two collaborative robotic arms  200   a  and  200   b  respectively for loading and unloading dishes into and out of the dishwashing system  100 . The dishwashing system  100  may also include a trolley  300   a  for storing and organizing dishes to be loaded onto the apparatus and a trolley  300   b  for storing and organizing dishes which are unloaded from the dishwashing system. 
     The dishwashing system  100  may include a plurality of treatment zones, such as, a loading zone, a prewash zone, a main wash zone, a post wash zone, a pre-rinse zone, a rinse zone, a drying zone, and an unloading zone. The prewash zone, main wash zone, and rinse zone may have their own water tank and pump for recirculating water to a specific filter and spray nozzle configured to spray a liquid onto a targeted zone in each treatment zone. 
     In the drying zone, the spray nozzle may be configured to spray air into a targeted zone. The air may be heated. As the dishes pass the spray nozzle the rotation of the dishes results in the target zone of the spray nozzle moving around the dishes. Thus, a large area of the dish is dried by the air spray as it passes through the target zone. Multiple spray nozzles may be used in the drying zone within the dishwashing apparatus to spray air onto multiple zones through which the dishes are conveyed resulting in highly targeted and high precision drying of the dishes. 
     Dishes to be loaded into the dishwashing system  100  are stored in the trolley  300   a  and organized according to their size (i.e. the diameter of the rim/lip of the dish). The collaborative loading arm  200   a  picks up a specifically sized dish and loads the dish onto the dishwashing apparatus such that the screw threads on the three rods  14 ,  16 , and  18  engage with the rim or the lip of the dish being loaded at approximately the same time. Once the dish is engaged with the screw thread on the rods the dish is conveyed through the dishwashing apparatus in the direction of the central axis of the dishwashing apparatus through the dishwashing system  100 . Thus the dishes pass through the target area that is sprayed by the liquid from the spray nozzle  12 . The water pump  104  supplies water to a water spray device and water spray nozzle  12  for spraying a liquid onto a target zone. A drying unit  107  such as an air dryer dries the dishes after passing through the targeted zone. The dishes exit the dishwashing apparatus and fall onto a soft conveyor belt system  500  from where the collaborative robotic arm  200   b  picks up the dishes and transfers them to a trolley  300   b  for storage. A control interface  102  allows user input of controls to the functions of the dishwashing apparatus  10  and dishwashing system  100  such as controlling the collaborative robotic arms, the rotation of the rods and the activation of the support systems. 
     As shown in  FIG. 2B  the dishwasher system  100  comprises a plurality of panels  154  fixed onto the upper and lower portions of the frame structure  150 . The plurality of panels  154  may act as a sound barrier, a liquid barrier, and/or a heat barrier. The panels  154  may be removable to allow access for maintenance. The dishwashing system  100  may include a window panel  153  to allow visual inspection. A dish loading point (e.g. absent panel  151 ) is provided to allow dishes to be placed onto the dishwashing apparatus. The collaborative robotic arms  200   a  and  200   b  may be mounted on the frame structure  150  by a support bracket  155 . 
       FIG. 2C  is a top down view of the dishwashing system shown in  FIGS. 2A and 2B . As shown in  FIG. 2C  the dishwashing apparatus  10  is installed in the dishwashing system  100 . The dishwashing system  100  includes the collaborative robotic arms  200   a  and  200   b  for loading and unloading dishes into and from the dishwasher apparatus. The collaborative robotic arms are attached to the system via the support bracket  155 . The dishwashing system  100  also includes a soft conveyor belt system  500 . Aligned with the dishwashing system  100  are two trolleys  300   a  for storing dishes to be loaded and  300   b  for storing dishes that are unloaded. 
     In use, the trolley  300   a  presents a dish to be loaded at the upper most surface of the trolley and at a protruding position such that the collaborative robotic arm  200   a  may easily engage with the plate and transfer it to the dishwashing apparatus  10 . Once a dish is transferred to the dishwashing apparatus  10 , the rods of the dishwashing apparatus engage with the dish as described above and convey it through the dishwashing system until it exits the dishwashing apparatus  10  and lands on the soft convey system  500 . The collaborative robotic arm  200   b  then engages with the dish picks it up and transfers it to the trolley  300   b  for storage. 
       FIG. 3A  is a perspective view of a position adjustment system of the dishwashing apparatus according to an embodiment of the present invention. As shown in  FIG. 3A  the dishwasher apparatus  10  is installed in a frame  110 . The dishwashing apparatus  10  is supported by the frame  110 , which may be positioned in the uppermost portion  101   b  of a dishwashing system. The dishwashing apparatus  10  may be placed in the system in a substantially horizontal arrangement or more preferably at an angle such that the loading end is lower than the unloading end, this generally reduces the volume of water from a first zone entering a second zone but allows for water from a second zone to flow backwards into a first zone therefore keeping the liquid in the more forward zone cleaner. As mentioned previously, the first rods  14 , second rod  16 , and the third rod  18  are arranged in a parallel configuration, at equal distances from a central axis. The separation of each of the first rod  14 , second rod  16 , and the third rod  18  from the central axis is configured or configurable to receive a plurality of dishes such that the screw thread  20  on each of the rods  14 ,  16 , and  18  engages with the circular rim or lip of the dishes. That is, the positioning of the first rod  14 , second rod  16 , and third rod  18  are adjustable by a position adjustment system coupled to the rods  14 ,  16 , and  18 . The position adjustment system allows the separation of each of the first rod  14 , second rod  16 , and the third rod  18  from the central axis to be adjusted to the size of a specific dish type. This allows the dishwashing apparatus and system to accommodate varying sized dishes. 
     The position adjustment system controls the positioning/distance of the first rod  14 , second rod  16 , and third rod  18  from the central axis. In particular the position adjustment system includes a gear  459  and belt  458  that control the positioning of the three rods  14 ,  16 , and  18 . The gear  459  and belt  458  is driven by a motor  457 . The position adjustment system is coupled to both ends of the rods. 
     The gear  459  and belt  458  are connected to a drive shaft  460  that is rotatably mounted to the frame  110 . The drive shaft  460  extends the substantial length of the frame  110 , and includes two pairs of gears: a pair of upper gears  463 , and a pair of bottom gears  464  that control the positioning of the three rods  14 ,  16 , and  18 . The upper gear  463  engages with a vertical positioning gear  461  via a chain  462  that drives a telescopic linear screw assembly  455  mounted on the frame  110 . The telescopic linear screw  455  is rotatable either clockwise or counter clockwise to adjust the vertical position of the first rod  14 . The telescopic linear screw  455  rotatably connects to the first rod  14  by a shaft mounting  456 . 
     The bottom gear  464  engages with a horizontal positioning gear  466  via a chain  465  and controls the horizontal position of the second and third rods  16  and  18 . The horizontal positioning gear  466  drives a symmetrically ended screw  452 , the symmetrically ended screw  452  has an external helical thread at its first and second end which is compatible with the external thread on a shaft support  453  which couples to one of the rods  16  and  18 . The shaft support  453  may further engage with a support rod  467  via a secondary support member  469 . As the horizontal positioning gear  466  rotates it causes the symmetrically ended screw  452  to rotate and therefore the shaft support  453  which engages with the threaded portion of the symmetrically ended screw  452  is caused to moves linearly along symmetrically ended screw therefore changing the horizontal positioning of the first and second rods  16  and  18 . Therefore the position adjustment system causes the positioning/distance of the first rod  14 , second rod  16 , and third rod  18  from the central axis to change thereby allowing the dishwasher assembly to be able to engage the circular rim or lip of the dishes of different sizes. The secondary support member  469  engages with the support rod  467  to prevent the twisting of the shaft supports  453  when being driven by the symmetrically ended screw  452  preventing jamming of the horizontal movement of the rods  16  and  18 . Location sensors  468  may be mounted onto shaft supports  453  to allow for monitoring and/or control of the positioning of the rods. 
     The belt  462  and the chain  465  may be provided as bead chains. The use of a bead chain system provides a flexible, positive drive mechanism to move the three rods  14 ,  16 , and  18 . The bead chain takes advantage of the spherical shape of the beads in the chain that allow it to swivel thereby providing an omni-directional positive drive that allows great freedom in the positioning and orientation of the gear belt/chain systems within the dishwashing apparatus  10  and system  100 . 
       FIG. 3B  is a perspective view of the dishwashing apparatus and position adjustment system separated into different zones by baffles according to an embodiment of the present invention. 
       FIG. 3B  shows a dishwashing apparatus and position adjustment system according to the embodiment shown in  FIG. 3A  including baffles  404  installed to segment/compartmentalize the dishwashing system. A pickup conveyer  500  may also be attached to the dishwashing system  100  at the unloading end. The pickup conveyer  500  provides a surface for the dishes to be conveniently picked up from and then stored away. A dirt cover  401  and a dry cover  405  may be placed over the symmetrically ended screws  452  at the loading and unloading ends of the dishwasher to prevent water and dirt from collecting on the screw thread of the symmetrically ended screw  452 . 
       FIG. 4A  shows a perspective view of the loading end of the dishwasher assembly according to an embodiment of the present invention.  FIG. 4A  shows the first rod  14 , second rod  16 , and third rod  18  movably attached to the frame of a dishwasher system  100 . A collaborative robotic arm  200   a  with a dish gripper assembly  202  is capable of loading a dish onto the dishwasher apparatus. 
       FIG. 4B  shows an expanded view of the second rod  16  engaging with the circular rim of lip of a dish while  FIG. 4D  shows an expanded view of the third rod  18  engaging with the circular rim of lip of a dish. As shown in  FIGS. 4B and 4D  the second and third rods  16 , and  18  may each include a non-threaded lead area  470  before the screw threaded portion of the respective rod. The non-threaded lead area  470  allows the collaborative loading arms  200   a  to correctly align the dishes with the dishwasher apparatus such that each rod can engage with circular rim or lip of a dish at the same time. A similar non-threaded portion can be found on the first rod  14  as shown in  FIG. 4A . 
       FIG. 4C  shows a perspective view of the leading end of a typical rod according to an embodiment of the present invention. The screw treaded  473  on the rod (any of rods  14 ,  16 , and  18 ) includes an engagement portion  471  with a offset portion  472  with a cut away segment  474  that allows for easy loading of the dishes into the dishwasher apparatus  10 . 
     In use, the dishwashing apparatus  10  is controlled by a controller using signals from encoders which monitor the rotational positions of the rods such that when the collaborative robotic arm  200   b  loads a dish into the apparatus the dish may slide along the non-threaded portion  470  of the rods until the dish reaches the engagement lead thread portion  471 . The controller uses the signals from the encoders to ensure that the engagement thread portion  471  is aligned and engages with the rim or lip of the circular dish at substantially the same time. The controller also ensures that all the rods  14 ,  16 , and  18  start and rotate at the same time and speed thereby ensuring the dishes gripped by the thread move through the dishwasher system  100  and follows the thread on all the three rod  14 ,  16 , and  18  at a fixed rate. The screw threaded has a predetermined pitch and by skipping pitches in the screw thread the spacing between the dishes loaded into the system  100  may be varied. 
       FIG. 5  shows a cross sectional view of the varying gape of the dishwashing apparatus according to an embodiment of the present invention. The differing size (gape) of the cross sectional area defined by the three rods  14 ,  16 , and  18  is shown in  FIG. 5 . By being able to select the appropriate gape size the dishwasher apparatus  10  may accommodate small, medium, and large sized dishes. 
       FIG. 6  shows a cross sectional view of the baffles. The baffles comprise a top plate  904  and two bottom plates  905 ,  906 . The three plates  904 ,  905 , and  906  provide a variable aperture around the dishwasher apparatus  10  and co-operate with it to define a central orifice through which the dishwasher apparatus  10  passes and in turn conveys the dishes. The two bottom plates  905  and  906  include a sliding mechanism  918  that controls the orientation of the two plates  905  and  906  as they slide against each other. 
     The co-operative movement of the plates  904 ,  905 , and  906  may be in response to the movement of the three rods  14 ,  16 , and  18 . Accordingly, the orifice may be sized appropriately to allow differently sized dishes to pass through this ensures that the baffle functions optimally irrespective of the size of the dishes, for example when small bowls are used the orifice size is small optimally preventing overspray from the bowls leaving the specific zone and when large plates are in use the orifice size is large optimally preventing overspray from the large plates leaving the zone. 
     In some embodiments, a drying zone is formed by a plurality of baffles spaced relatively close together, for example between 5 cm and 50 cm apart. Extended nozzles are arranged at the top of the apparatus and are configured to blow air downward though the space between the baffles. The air may be heated. It is noted that in such an arrangement, the air flow is incident on the whole of each dish or substantially the whole of each dish from above. The effect of such an air flow is to is to drive any moisture downwards and thus to dry the dishes in an efficient manner. 
       FIG. 7A  shows the dishwashing apparatus engaging with large sized dishes according to an embodiment of the present invention.  FIG. 7B  shows the dishwashing apparatus engaging medium sized dishes according to an embodiment of the present invention.  FIG. 7C  shows the dishwashing apparatus engaging bowls according to an embodiment of the present invention. 
     As shown in  FIGS. 7A, 7B, and 7C , the loading of dishes onto the dishwashing apparatus can be varied to control the separation of dishes. The space in between the dishes is configurable according to the shape and/or need of the dish by varying the number of screw threads in between the dishes. For deep dishes such as the bowls shown in  FIG. 7C , the separation may be increased to allow the interior of the bowl to be cleaned. 
     In an embodiment, each of the three rods  14 ,  16 , and  18  are driven by an individual drum motor assembly  451  contained within the respective rod. 
       FIGS. 8A to 8D  show a cross sectional views of a drum motor assembly inserted within one of the three rods of the dishwasher apparatus according to an embodiment of the present invention. 
     As shown in  FIG. 8A  one of the rods  14 ,  16 ,  18  houses a drum motor assembly  476 . As shown in  FIG. 8B  the rod may comprise a metal shaft  475  (e.g. a steel shaft) and a hollow core  451  in which the drum motor assembly  476  is inserted. The screw thread is on the external facing of the metal shaft  475 . The screw thread  473  may be formed from plastic or rubber material. As shown in  FIG. 8C  the drum motor  476  includes an engagement end  484  that engages with the metal shaft  475  via a locking mechanism at  485  such as a pin lock  486  that firmly engages with the shaft at the locking position  485 . The drum motor assembly  476  also includes a first connecting shaft  477  for connecting the rod via the drum motor to the frame. Thus the drum motor can cause the rod to rotate around its central axis. At a second end  479  of the rod there is hole which receives a shaft  480  which couples the second end  479  of the rod to the frame and allows the rod to rotate. The shaft has a hollow body  481  to allow wiring to be connected an encoder. The drum motor system  451  also includes an encoder  483  and a plate  482  for determining the rotational position of the rod. Bearings  478  allow the rod to rotate against the shaft  480 . 
     Powering of the drum motor assembly causes the rod and external screw thread to rotate about the connection points to the dishwasher assembly and this rotation causes the dishes to move along the helical screw thread when engaged. 
       FIGS. 9A and 9B  show a perspective and a side view of the loading end of the dishwashing apparatus according to an embodiment of the present invention. 
     The dishwashing system as described above in  FIG. 3B  may further comprise at least one spray device  900  for spraying liquid onto dishes. The spray device  900  has an inlet, into which liquid can be pumped to flow to a plurality of spray nozzles  903 . The direction of the nozzles outlets may be varied from spray nozzle to spray nozzle such that different areas can be targeted. The spray nozzles are coupled to the spray device via T-junctions  902 . The each of the spray nozzles may be a hollow cone nozzle, a full cone spray nozzle, and/or a flat fan pray nozzle, optionally the water spray device  900  may utilize a variety of spray nozzle types to optimize the spraying of the target area. 
     As shown in  FIGS. 9A and 9B , the water spray device  900  has a circular/semi-circular/ring shape and the T-junction elements  902  with nozzles are spaced around the circumference of the water spray device  900  allowing water to be sprayed from multiple directions (upwardly, downwardly and from the left and right sides relative to the direction of movement of the dishes) towards the dishes. A plurality of spray devices  900  may be arranged one behind each other along the length of the dishwasher and/or in different treatment zones. 
     As shown in  FIGS. 9A and 9B , the baffle plates  904 ,  905 , and  906  are held in place by support wires  910  that couple to the dishwashing system. As described above in relation to  FIG. 6 , the baffle plates  904 ,  905  and  906  may include a sliding mechanism that controls the orientation of the two plates  905  and  906  as they slide against each other. 
       FIGS. 10A and 10B  respectively show a perspective view and a side view of the unloading end of a dishwashing system according to an embodiment of the present invention. 
     As shown in  FIGS. 10A and 10B , the dishwashing system  100  includes a knock down system for unloading the dishes from the dishwasher apparatus  10 . This knock down system comprises a pair of rotating rods  511 , each with a rotator  512  that includes a plurality of soft fins  513 . The rotating rods are each driven by a motor  510 . The plurality of soft fins  513  engage with the dishes as they leaves the screw threaded portion of the rods  14 ,  16 , and  18  and knocks it down from the dishwasher apparatus  10 . As shown in  FIGS. 10A and 10B , the dishes land on a pickup conveyor system  500  comprising a belt  502  with soft fins  503  to cushion the landing of the dish after it is knocked down. The pickup conveyor  500  may include a movable stopper  507  that correctly guides the dishes to a center point position from where it can be easily stored away either by hand or by the collaborative robotic arm  200 . It is noted that this configuration allows the dishes to exit the dishwashing system in an upward facing orientation which provides for easy later processing. As shown in  FIGS. 10A and 10B , the top surface  517  of the dishes  621  is facing upwards when the dishes  621  land on the conveyer  500 . 
       FIGS. 10C and 10D  show views of a collaborative unloading arm retrieving a dish from the unloading end of a dishwashing system according to an embodiment of the present invention. As shown in  FIGS. 10C and 10D , the movable stopper  507  controls the position of a dish  621  on the pickup conveyer  500 . The dish  621  can thus be lifted by a gripping mechanism  255  attached to the collaborative unloading arm  200   b . The stopper  507  also prevents this dishes from running off the pickup conveyor  500 . As illustrated in  FIG. 10D , the bottom surface  516  is facing downwards when the dishes are lifted. It is noted that the since the lip/rim of the dishes is located around the top surface of the dishes, the gripping mechanism  255  can move under the lip/rim of the dishes when they are in the upward facing position. 
       FIGS. 11A and 11B  show a perspective view and a top view of a compact dishwashing system according to an embodiment of the present invention. The compact dishwashing system comprises a compact loading unit  700  and a compact unloading unit  800 . The compact loading unit  700  is arranged at a loading point  151  and the compact unloading unit  800  is arranged at an unloading point  152 . The compact dishwashing system  125  has a lower portion  101  which houses a filtration system  103 , a water pump  104 , a filter control unit  105  and a water holding tank  106 . A control interface  102  is arranged at the side of the compact dishwashing system  125 . As shown in  FIGS. 11A and 11B , the compact dishwashing system  125  is housed within a housing comprising a plurality of panels  154 , in some places windows  153  are provided in the housing. The compact dishwashing system comprises a compact frame  400  which supports a compact dishwashing apparatus  450 . 
       FIGS. 12A to 12D  show details of a dish lifting mechanism of a compact loading unit according to an embodiment of the present invention. The compact loading unit  700  comprises a base portion  701  with two guide plates  702  which support a platform  703 . The vertical position of the platform can be changed by an elevator mechanism  704 . A pair of feeder housings  705  are provided at the top of the dish lifting mechanism. Grippers  706  are located in the feeder housings  705 . The grippers  706  are configured to grip the lips of dishes. 
     As shown in  FIG. 12A , the elevator mechanisms  704  can adjust the elevation height  712  of the platform  703  according to the stack height  713  of dishes loaded on the platform  703  at the loading point  151 . Thus, the top of the stack of dishes is adjacent to the grippers  706  within the feeder housings  705  as shown in  FIG. 12B . 
     As shown in  FIGS. 12C and 12D , the grippers move to an engaged position  707  and engage with the lip/rim  708  of a dish. A sensor  709  located on a guide plate  710  may sense the dish position and size. The grippers in the engaged position  707  then move to a lifted position  714  as shown in  FIG. 12C  this provides a gap  711  between the top dish and the lower dishes to allow the top dish to be loaded on to the dishwashing apparatus. 
       FIGS. 13A to 13E  show views of a dish loading arm system according to an embodiment of the present invention. The system may form a compact dish loading unit  700  for loading dishes onto a compact dishwashing apparatus  450  supported by a compact frame  400 . An arm  758  is mounted on an arm assembly  750 . The arm assembly  750  comprises a support bar  751  and a base extension  752 . The arm  758  is attached to the arm assembly  750  at a pivot point  753 . A curved rib  754  extends from the arm  758 . The rib curved rib  754  provides an arc platform  756 . A motor  757  located on the support bar  751  is used to cause the arm  758  to rotate around the pivot point  753 . The arm is provided with a telescopic arm  759  which allows the length of the arm to be adjusted to accommodate different dish sizes. 
     As shown in  FIG. 13B , the arm  758  can move rotationally around the pivot point  753  through a movement path  771 . In order to load dishes onto the dishwashing apparatus, initially, the dish lifting mechanism raises the top dish of a stack through a gap  711 , then the arm  758  engages with the top dish and moves through the movement path  771  to load the dish onto the dishwashing apparatus. 
     As shown in  FIG. 13C , a dish is held in three points by the arm mechanism. An extension assembly comprising an extension arm  761  with a gripper  762  at the end supports the rim/lip of the dish at the point closest to the pivot point  753 . The sides of the dish are supported by two side grippers  763  on telescopic arms  764  which extend from structure holes in the telescopic arms  759  that couple to the arms  758  attached to the pivot points  753 . 
     The arm assembly is moved by a cable  767  as shown in  FIG. 13D . The cable  767  is attached to each end of the curved rib  754 , and the cable is also looped around a spindle attached to the motor  757  mounted on the support arm  751 . When the motor  757  causes the spindle to rotate, the arm assembly moves rotationally around the pivot  753 . 
       FIG. 13E  shows the arm assembly in an upright position in which a dish is loaded onto the dishwashing apparatus. As illustrated in  FIG. 13E , the dish is gripped at three gripping points  770 . Once the dish is engaged by the threaded rods of the dishwashing apparatus, the dish is released at the three gripping points  770  and the arm assembly moves back through a return path  772  to load the next dish. 
       FIGS. 14A to 14D  show views of a dish unloading system according to an embodiment of the present invention. The system may form a compact dish unloading unit  800  as shown in  FIGS. 14A and 14B . The compact dish unloading unit  800  comprises a base portion  801  with two guide plates  802  which support a platform  803 . The vertical position of the platform can be changed by an elevator mechanism  804 . The base portion  801  and guide plates of the compact dish unloading unit  800  may be configured in an analogous manner to corresponding parts of the compact loading system  700  shown in  FIGS. 13A and 13B . 
     The elevator mechanism  804  is configured to adjust the elevation height of the platform  803  according to the number of dishes loaded on the platform  803 . Thus, as dishes are loaded on to the platform  803 , the elevation mechanism  804  moves the platform downwards in a vertical direction such that the upper surface of the stack of dishes on the platform is maintained in an effectively constant position, thereby allowing further dishes to be unloaded to approximately the same position. Thus, when dishes are unloaded, the distance though which they are moved does not change for different heights of the stack of unloaded dishes. 
     The compact dish unloading system  800  comprises an unloading arm system which unloads dishes  621  from the dishwashing apparatus  450  and stacks the dishes  621  on the platform  803 . The unloading arm system  850  comprises a pair of first extension arms  851  that are mounted on symmetry arms  860  of the assembly  450 . The symmetry arms  860  are coupled to the bottom pair of rods of the dishwashing apparatus. As shown in  FIG. 14B , the first extension arms  851  extend from the end of the dishwashing apparatus parallel to the axis of the rods. Each of the first extension arms  851  has an operating channel  852  which is a slit running substantially along the length of the first extension arms  851 . A second pair of extension arms  854  is respectively coupled to the first extension arms  851 . Motors  853  located at one end of the second extension arms  852  are configured to move the ends of the second extension arms  854  along the operating channels  852  in the first extension arms  851 . Further, a pair of gear systems  859  respectively control the rotational position of the second extension arms  854  relative to the first extension arms  851 . 
     The second extension arms  854  each have respective gripper channels  855  which are slits running substantially along the length of the second extension arms  854 . Gripper extensions  856  are arranged in the gripper channels  855 . The gripper extensions  856  have grippers  861  attached to their ends which are configured to grip the rim of the dish  621  which is unloaded from the dishwashing apparatus. 
     A centre shaft  857  extends from the pivot point of one of the second extension arms  854  with the corresponding first extension arm  852 . The centre shaft  857  extends into the gap between the pair of first extension arms  852 . A centre extension portion  858  is attached to the end of the centre shaft  857 . In the configuration shown in  FIG. 14A , the centre extension portion  858  has a support gripper  862  attached to the end which is configured to support the rim of the dish  621  as the dish is unloaded from the dishwashing apparatus. 
     The process of unloading a dish from the dishwashing apparatus will now be described with reference to  FIGS. 14C and 14D . As shown in  FIG. 14C , the grippers  861  move to an engagement position and engage with the upper lip/rim of a dish  621  which is in a vertical position having moved to the end of the threaded parts of the three rods. The support gripper  862  attached to the centre extension  858  engages with a lower end portion of the lip/rim of dish  621 . 
     Then, the gear  859  and motor  853  systems move the pair of second extension arms  854  along the respective operating channels  852 . The gear  859  and motor  853  systems then cause the second pair of extension arms  854  to rotate such that the dish  621  moves to a horizontal position for unloading as shown in  FIG. 14D . The dish is then released by the grippers  861  and the support controller  862 , and placed onto the platform  803  (or the top of a stack of dishes on the platform  803 ). Then, the platform moves downward  805  so that the next dish can be unloaded and placed on top of the stack. 
     The unloading of dishes in the manner described above has the advantage that the unloaded dishes are stacked facing upwards which allows for easy further processing of the dishes. 
       FIG. 15  shows a trolley for use in a dishwashing system according to an embodiment of the present invention. As shown in  FIG. 15 , the trolley  300  organizes the dishes according to their size (i.e. the diameter of the rim/lip of the dish). The trolley  300  may be used to store and organize dishes to be loaded onto the dishwashing apparatus (e.g. trolley  300   a ) or for storing dishes which are unloaded from the dishwasher apparatus (e.g. trolley  300   b ). 
     The trolley  300  comprises a frame, caster wheels  304  and a base  305 . A control and driving assembly  301  is located on the side of the trolley  300 . The control and driving assembly allows the position of the trolley  300  relative to the dishwashing apparatus to be controlled. This allows dishes to be loaded or unloaded from the trolley  300 . The control and driving assembly  301  comprises a position sensor  302  which detect the location of the trolley relative to the dishwashing system. The trolley  300  may be moved in along the direction  303  of the control and driving assembly  301  by the dishwashing apparatus. 
     Movement of the trolley allows the collaborative robotic arm  200   a  or  200   b  to do minimal work by ensuring that the dishes are moved from or to substantially the same position on the trolley in the  303  direction when the trolley is adjacent to the dishwashing apparatus as shown in  FIG. 2A to 2D . 
     A plurality of plate cart assemblies  600  are positioned on the base of the trolley  305 . The plate cart assemblies allow the dishes to be arranged into stacks according to their size for loading and/or unloading. As shown in  FIG. 15 , the plate cart assemblies include large sized plate cart assemblies  600   a , medium sized plate cart assemblies  600   b , and small sized plate cart assemblies  600   c , for holding large, medium and small sized dishes respectively. 
       FIG. 16  shows examples of trolleys for use in a dishwashing system according to an embodiment of the present invention. 
     In one example the trolley  354  has a circular base and can be rotated circularly  355  about its central axis. The plate cart assembles may be arranged in according to different plate cart layouts  353 . For example, for a trolley  300   a  may have a layout  353   a  for dirty plates and a trolley  300   b  may have a layout  353   b  for clean plates. The trolley may include attachment space  351  for attachments other than plate cart assemblies. This attachment space  351  may contain a wastage collection container  352  for collecting waste from dirty plates and dishes. 
       FIG. 17A to 17C  show details of a dish lifting mechanism of a dish cart assembly unit and movement of the dish by a robotic arm in a system according to an embodiment of the present invention. 
     The dish cart unit  600  comprises a base  602  and four pillar supports  603  arranged at equal distances from the center of the base  602 . Located within the four pillar supports  603  is a dish support base  601  that is movable in a vertical direction  630  from a lower position at the base of the pillar supports to an upper most position at the top of the pillar supports. The vertical position of the dish base support can be changed by an elevator mechanism. 
     As shown in  FIGS. 17A and 17B , the movement of the dish support base  601  allows the position of the top dish in a stack of dishes to be controlled. Thus, the top dish can be moved to a position for loading by a robotic arm  200   a.    
     As shown in  FIG. 17C , the top of each of the pillar supports  603  comprises a dish lifting mechanism which lifts the top dish of the stack of dishes so that it can be easily gripped by the robotic arm  200   a . The dish lifting mechanism comprises a driver portion  604  which is located inside each of the pillar supports  603 . A lifting arm  605  extends upwards from the driver portion  604 . A dish engagement foot  606  is located at the end of each of the lifting arms  605 . 
     The driver portion  604  can cause the lifting arms  605  to move upwards out of the support pillars  603 , thus when the dish engagement foot  606  contacts the rim of a dish, the dish is lifted upwards from the top of the stack. 
     When the dish is lifted upwards, it can be gripped by a dish engagement portion  201  at the end of the robotic arm  200   a . The dish engagement portion  201  of the robotic arm  200   a  comprises a dish gripper extension  202  and a dish gripper  203 . The dish gripper  203  has recesses  205  which are shaped to receive the rim of a dish. As shown in  FIG. 17C , the dish gripper extension  202  allows the dish gripper  203  to be moved to a position in which the rim of the upper-most dish engages with the recesses  205 . Thus, the upper-most dish can be lifted from the stack and loaded onto the dishwashing apparatus. 
     In the dishing washing and drying apparatus described above, dishes having a circular rim or lip may be washed and dried. In order to allow other items such as cutlery and utensils and non-circular shaped dishes to be washed and/or dried in the apparatus, the cage assembly described below with reference to  FIG. 18  and the dish holders described below with reference to  FIGS. 19A to 19C  may be used. 
       FIG. 18  shows a cutlery and utensil cage assembly with a circular lip/rim for use in a dishwashing system according to an embodiment of the present invention. As shown in  FIG. 18 , the cutlery and utensil cage assembly  650  comprises a plurality of rings  651  spaced along a plurality of reinforcing rods  652  to form a cage having a cylinder shape. A mesh including an end grid  654  surrounds the internal portion of the cage framework defining a cavity  656  within which utensils can be placed. The cutlery utensil cage assembly  650  includes an opening  655  that allows access to the internal cavity  656 . 
     In use, the cutlery and utensil cage assembly  650  is loaded onto a dishwasher assembly in a similar fashion as dishes except that instead of engaging with the lip/rim of the dish the threads on the rods of the dishwashing apparatus engages with the lip/rims of the plurality of rings  651  arranged on the outer surface of the cutlery and utensil cage assembly  650 . Accordingly, the cutlery and utensil cage assembly  650  is then caused to move through the dishwashing apparatus and rotates as it passes through a target zone of a spray nozzle. 
       FIGS. 19A to 19C  show dish holder devices for use in a dishwashing system according to an embodiment of the present invention. 
     As shown in  FIG. 19A  an irregular shaped dish  659  is attached to a dish holder device  658 . The dish holder device  658  has a circular rim  657  which engages with the thread on the rods of the dishwashing apparatus and thus allows the irregular shaped dish to be washed in the dishwashing apparatus described above. 
       FIGS. 19B and 19C  show examples of a dish holder device  658  which comprises a frame which grips dishes allowing them to be washed in dishwashing apparatus described above. In each case the dish holder  658  device has a circular rim  657  which engages with the thread on the rods of the dishwashing apparatus and thus allows the irregular shaped dish to be washed in the dishwashing apparatus described above. As shown in  FIG. 19B , a rectangular dish  660  is held by the frame of the dish holder  658  and as shown in  FIG. 19C  an oval dish  661  is held by the frame of the dish holder device  658 . 
       FIG. 20  is a block diagram showing the control system of a dishwashing system according to an embodiment of the present invention. As shown in  FIG. 20 , the control system  900  comprises a main program  910  which runs on a central processing unit (CPU) located in the control interface  102  described above. The control system  900  further comprises a shaft rotation sensing and control module  920 . The shaft rotation sensing and control module  920  comprises a shaft speed and synchronizing controller  922 , a dish count and location sensing module  924  and a load/unloading reference point module  926 . The shaft rotation sensing and control module  920  is coupled to sensing and control modules of the first shaft assembly  930 , the second shaft assembly  940  and the third shaft assembly  950 . The first shaft assembly  930  comprises a 12 o&#39;clock encoder  931  which is configured to count rotations of the first rod  14  of the dishwashing apparatus  10 ; an absolute rotary encoder  932  which is configured to determine the rotational position of the first rod  14  of the dishwashing apparatus; a speed controller  933  for the drum motor  934  that drives the first rod  14 ; the drum motor  934  itself; and gearing and leads  935  coupled to the drum motor  934 . The second shaft assembly  940  and the third shaft assembly  950  are configured in an analogous manner to the first shaft assembly  930  and so the descriptions are omitted. 
     The control system  900  further comprises a dish size controller  960 . The dish size controller  960  comprises a shaft support positioning system  961  comprising the motors that adjust the positions of the rods to allow different sized dishes to be received in the dishwashing apparatus, and a dish diameter center distance controller  962  which controls the shaft support positioning system  962 . 
     The control system  900  further comprises loading systems  970  and unloading systems  980  which may comprise robotic arms or loading/unloading systems as described above with reference to  FIGS. 10A to 10D, 11A to 11B, 13A to 13E, and 14A to 14D . 
     The control system  900  further comprises supportive function systems  990 . The supportive function systems comprise water pump systems  991 , waste collection systems  992 , a filter control system  993 , an air dryer  994 , heating elements  995 , power distribution  996 , the water tank controller  997  and various sensors  998  which may include temperature sensors, water/liquid level sensors, proximity sensors etc. 
     In use, the shaft rotation sensing and control module  920  receives signals from each of the shaft assemblies and controls the motor speed controllers of each if the shaft assemblies such that rotational position of the three rods is aligned, this ensures that dishes are engaged by the threads on the three rods at substantially the same time. The dish count and location sensing module  924  determines the count and location of dishes on the apparatus, this may be through sensors located in the system that determine the locations of dishes in the system. 
     The main program  910  may use sensed data from trolleys to determine that a change in position of the rods is required to accommodate a different dish size. Then once it has been determined that there are no longer dishes within the apparatus, for example by sensing the number of dishes loaded onto the apparatus and counting the number of unloaded dishes, the dish size controller  960 , causes the position of the rods to be adjusted to accommodate the new dish size. 
     The loading system  970  may also be controlled according to the dish type to adjust the spacing of dishes as described above in relation to  FIGS. 7A to 7C . 
     The supporting system functioning  990  may also be controlled according to the sensed position of dishes within the apparatus, for example, if there are a sequence of operational zones, these may be initiated once dishes have entered that specific zone. For this control the position of dishes within the apparatus may be sensed using sensors or may be calculated from the rotational speed of the rods. 
     In the embodiments described above, the lower two rods are arranged at the same vertical height and there is a single upper rod. In some embodiments, there is a single lower rod and two upper rods. Such an embodiment is described below with reference to  FIGS. 21A to 21C . 
       FIGS. 21A to 21C  show dishwashing apparatus according to an embodiment of the present invention.  FIG. 21A  is a perspective view,  FIG. 21B  is a side on view and  FIG. 21C  is an end on view.  FIG. 21C  also shows positions of the rods of the dishwashing apparatus which are movable to accommodate different dish sizes. 
     In this embodiment, the dishwashing apparatus  2100  comprises a first rod  2114 , a second rod  2116  and a third rod  2118 . As described above, each of the first rod  2114 , the second rod  2116  and the third rod  2118  are provided with a screw thread  20  on an outer surface. Each rod is rotatable about a respective longitudinal axis. The first rod  2114 , second rod  2116 , and the third rod  2118  are arranged in a parallel configuration, at equal distances from a central axis. When the first rod  2114 , second rod  2116 , and the third rod  2118  are rotated about their respective axes, dishes are caused to move relative to a spray nozzle in the direction of the central axis and rotate as the pass through a target zone. In this embodiment, the first rod  2114  is arranged as a lower rod, the position of which is not movable, and the second rod  2116  and the third rod  2118  are arranged as upper rods each occupying a position higher than the first rod  2114 . 
     The dishwashing apparatus  2100  is mounted on two base portions  2102  which are arranged at opposing ends of the dishwashing apparatus  2100 . The two base portions  2102  have raised pivot points  2104  at each side and cutaway portion in the center. Movable arms  2106  are attached to the pivot portions  2104 . A fixed arm  2108  is attached at the center of the cutaway portion of each base portion  2102 . The fixed arms  2108  support the first rod  2114 . Each end of the first rod  2114  is attached to one of the fixed arms  2108 . The movable arms  2106  on one side of the based portions  2102  support the second rod  2116  and the movable arms on the opposite side of the base portions  2102  support the third rod  2118 . Two shafts  2110  run between the two base portions  2102  between the pivot points  2102  parallel to the first rod  2114 , the second rod  2116  and the third rod  2118 . The movable arms  2106  are coupled to the shafts  2110  so that when the shafts  2110  turn in the pivot points  2104 , the movable arms  2106  also move around the pivot points  2106  such that the second rod  2116  and the third rod  2118  move closer together or further apart. 
     Baffles  2112  are mounted on the shafts  2110  such that the baffles can be moved together and further apart with the second rod  2116  and the third rod  2118 . 
     A loading system  2120  is provided at one end of the dishwashing apparatus  2100 . The loading system  2120  comprises a pair of belts  2122  which are provided with fins that support dishes  30  to be cleaned. Movement of the belts  2122  causes the dishes  30  to move upwards. A pair of guides  2124  are provided with grooves  2126  which receive the rim or lip of the dishes  30  and are curved such the dishes  30  are guided from a horizontal position to a vertical position by following the grooves  2126 . An actuator  2128  acts to push the dishes  30  from a position supported by the fins of the belts  2122  into the grooves  2122 . 
     As described above in relation to  FIG. 1 , once a dish is placed in a vertical position between the rods, the rotation of the rods causes the dish to move in a horizontal direction parallel to the rods through a cleaning and/or drying zone. 
       FIG. 21C  shows different possible positions of the movable arms  2106  to accommodate different sizes of dish. As shown in  FIG. 21C , with the movable arms  2106  in a first position, the second rod is in a first position  2116 A and the third rod is in a first position  2118 A this accommodates a large dish size  30 A. To accommodate a medium dish size  30 B, the movable arms  2106  can be moved inwards such the second rod is in a second position  2116 B and the third rod is in a second position  2118 B. To accommodate a small dish size  30 C, the movable arms  2106  can be moved to a third position in which the second rod is in a third position  2116 C and the third rod is in a third position  2118 C. 
     When the movable arms  2106  are moved, the baffles  2112  are also moved such that gap between the baffles  2112  accommodates the dishes being washed/dried. Further, the positions of the belts  2122  and guides  2124  of the loading system  2120  are also movable to accommodate different dish sizes. In this embodiment, the position of the first rod  2108  is not movable. 
     Whilst the foregoing description has described exemplary embodiments, it will be understood by those skilled in the art that many variations of the embodiments can be made within the scope and spirit of the present invention. 
     For example, while in the embodiments described above there are three rods which are each threaded to move dishes through the dishwashing apparatus, those of skill in the art will appreciate that four or more rods may be used in an analogous manner.