Patent Publication Number: US-11642000-B2

Title: Dishwashing machine and method

Description:
CROSS REFERENCE TO A RELATED APPLICATION 
     This application is a US 371 application from PCT/EP2018/073266 entitled “A DISHWASHING MACHINE AND METHOD” filed on Aug. 29, 2018 and published as Wo 202/043285 A1 on Mar. 5, 2020. The technical disclosures of every application and publication listed in this paragraph are hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a dishwashing machine and a method of controlling a dishwashing machine. 
     BACKGROUND 
     Dishwashing machines (also referred to as dishwashers) are used for washing items such as crockery and cutlery. A known dishwashing machine comprises a washing compartment for holding one or more items to be washed, and a washing mechanism for washing those items. Such a washing mechanism typically comprises one or more spray arms. Typically a user can select from a plurality of pre-defined washing cycles via a user interface on a front face of the dishwashing machine 
     SUMMARY 
     According to a first aspect disclosed herein, there is provided a dishwashing machine comprising: a controller; a spray arm assembly comprising a spray arm having one or more spray holes for spraying a washing load with water, and a pipe for delivering water to the spray arm; a pump for pumping water through the pipe and to the spray arm; the pipe being constructed and arranged to at least partially restrict flow of water from the pump to at least a part of the spray arm dependent on spray arm orientation relative to the pipe, a power consumption of the pump thereby being dependent at least in part on spray arm orientation relative to the pipe; and the controller being configured to monitor the power consumption of the pump in order to determine rotational information of the spray arm. 
     By monitoring the cycle of power consumed by the pump, the controller can accurately determine when the spray arm is blocked by an obstruction in the dishwashing machine, such as an incorrectly placed item to be washed. This is because when the spray arm is rotating normally, the power consumption of the pump follows a particular expected cycle. If the power consumption of the pump differs from this cycle then the controller knows that the spray arm is not rotating correctly. This arrangement helps to prevent damage to the spray arm and the water pump since the washing cycle can be stopped if the spray arm is blocked. It also ensures that the quality of cleaning provided by the dishwashing machine is not impacted by the spray arm not rotating correctly. 
     In an example, the pipe comprises a barrier for at least partially restricting the flow of water to the spray arm. 
     In an example, the barrier is integrally formed with the pipe. 
     In an example, the barrier projects upwardly from an end face of the pipe. 
     In an example, the one or more spray holes are oriented so as to facilitate rotation of the spray arm when water is ejected from the one or more spray holes. 
     In an example, the spray arm comprises a first side and a second side, and wherein the first side of the spray arm has more spray holes than the second side of the spray arm. 
     In an example, the controller is configured to determine the rotational information of the spray arm by comparing a determined power consumption of the pump with an expected power consumption of the pump. 
     In an example, the controller is configured to cause an alert to be output to a user when the determined power consumption of the pump differs from the expected power consumption of the pump by more than a predetermined value. 
     In an example, the controller is configured to cause an alert to be output to a user when the determined power consumption of the pump differs from the expected power consumption of the pump for longer than a predetermined time period. 
     According to a second aspect disclosed herein, there is provided a method comprising: monitoring a power consumption of a pump for pumping water to a spray arm assembly of a dishwashing machine, a power consumption of the pump being dependent at least in part on an orientation of the spray arm relative to a pipe that is constructed and arranged to at least partially restrict flow of water from the pump to at least part of the spray arm; and determining rotational information of the spray arm using information from the monitored power consumption of the pump. 
     In an example, the method comprises determining rotational information of the spray arm by comparing a determined power consumption of the pump with an expected power consumption of the pump. 
     In an example, the method comprises causing an alert to be output to a user when the determined power consumption of the pump differs from the expected power consumption of the pump by more than a predetermined value. 
     In an example, the method comprises causing an alert to be output to a user when the determined power consumption of the pump differs from the expected power consumption of the pump for longer than a predetermined time period. 
     In an example, the method comprises halting a washing cycle of the dishwashing machine when the determined power consumption of the pump differs from the expected power consumption of the pump. 
     In an example, the method comprises automatically restarting the washing cycle when it is determined that the alert has been cleared. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To assist understanding of the present disclosure and to show how embodiments may be put into effect, reference is made by way of example to the accompanying drawings in which: 
         FIG.  1    shows schematically a dishwashing machine according to an example; 
         FIG.  2    shows schematically a view of a spray arm assembly according to a first example, with the spray arm in a first orientation; 
         FIG.  3    shows schematically a view of a spray arm assembly according to a first example, with the spray arm in a second orientation; 
         FIG.  4    shows schematically a view of a spray arm assembly according to a second example, with the spray arm in a first orientation; 
         FIG.  5    shows schematically a view of a spray arm assembly according to a second example, with the spray arm in a second orientation; 
         FIG.  6    shows schematically a plan view of a spray arm assembly according to a second example, with the spray arm in a first orientation; 
         FIG.  7    shows schematically a plan view of a spray arm assembly according to a second example, with the spray arm in transition between a first orientation and a second orientation; 
         FIG.  8    shows schematically a plan view of a spray arm assembly according to a second example, with the spray arm in a second orientation; 
         FIG.  9    shows schematically a plan view of a spray arm assembly according to a second example, with the spray arm in transition between a second orientation and a first orientation; and 
         FIG.  10    shows schematically a plot of power consumption of a pump against time, according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure has applicability to dishwashing machines (also referred to as dishwashers). Dishwashing machines are used to automate the washing of items associated with food preparation and/or cooking and/or eating. Such items include crockery such as plates, bowls, cups, mugs etc. Such items may also include cutlery such as knives, forks, spoons, or indeed any other cooking or eating utensil. Other items that may be washed include glassware, food containers etc. 
       FIG.  1    schematically shows an example of a dishwashing machine  100 . The dishwashing machine  100  comprises a main body  102 , within which there is a washing compartment  104 . The washing compartment  104  comprises a lower portion  106  and an upper portion  108 . The lower portion  106  comprises a tray or rack  110  for holding items to be washed, and the upper portion  108  comprises a tray or rack  112  for holding items to be washed. The racks  110  and  112  can be moved in and out of the washing compartment  104  on roller assemblies. 
     Items to be washed are schematically shown at  114 . In this case the items to be washed are schematically represented by plates  116  and  118  on rack  112 , and plates  120  and  122  on rack  120 . Of course there may alternatively be any other type of item to be washed or combination of items to be washed. In the example of  FIG.  1    a washing mechanism  123  comprises spray arm  124  in lower portion  106 , and spray arm  126  in upper portion  108 . In other examples the upper spray arm  126  is omitted. Each spray arm comprises a series of holes or nozzles which can spray water upwardly towards the items to be washed  114 , while the spray arms  124  and  126  rotate. These are commonly referred to as spray holes. They may also be referred to as water outlets. Rotation of the spray arms  124  and  126 , whilst ejecting water therefrom, helps to clean the items in a washing load. 
     In the example of  FIG.  1    the spray arm  124  is connected to pipe  125 . The pipe  125  enables rotation of spray arm  124  about a central axis of the pipe  125 . The pipe  125  and spray arm  124  may be considered to be comprised in a spray arm assembly  121 . In the example of  FIG.  1    the spray arm  126  is connected to pipe  127 . The pipe  127  enables rotation of spray arm  126  about a central axis of the pipe  127 . 
     The dishwashing machine  100  further comprises water inlet  128  and water outlet  130  for enabling water to be fed to and taken away from the dishwashing machine respectively. In some examples a heater element (not shown) is provided for heating water as necessary. In other examples hot and cold water is drawn from a building&#39;s supply as required. A power connection is schematically shown at  132 , which enables the dishwashing machine to be connected to mains electrical power for powering the dishwashing machine. 
     A water pump is schematically shown at  150 . The water pump  150  is constructed and arranged to distribute water around the dishwashing machine  100 . For example, the water pump  150  can pump water to spray arms  124  and  126 . Water that has been sprayed falls back down to a base or sump  152  of the dishwashing machine  100 , from where that water can be recycled (after filtering, in some examples) by the pump  150 . 
     In some examples rotation of the spray arms  124  and  126  is effected by the force of water being ejected from spray holes of the spray arms. In such examples the spray holes may be arranged and/or oriented so as to facilitate such rotation. Additionally or alternatively one or more motors, shown schematically at  148 , may be provided for powering rotation of the spray arms  124  and  126 . 
     A controller is schematically shown at  134  for controlling operations of the dishwashing machine. The controller  134  can, for example, cause the dishwashing machine to operate according to one or more pre-determined washing cycles selected via a user interface  136 . The available washing cycles may differ from each other by temperature and/or duration, for example. Via the user interface  136  a user may also be able to select whether the washing cycle is for a full or half load. A display  138  is also provided which can display information to the user. This may include information such as confirming a user&#39;s washing cycle selection, as well as information such as time remaining of a washing cycle that is in progress. 
     A door of the dishwashing machine is schematically shown at  140 . The door  140  is connected to main body  120  via hinges  142  and  144 . In  FIG.  1    the door is in an open position enabling access to washing compartment  104 . The door  140  may be moved to a closed position so that the washing compartment  104  is then substantially enclosed. The door  140  may also include a receptacle for holding dishwashing detergent (e.g. a dishwashing machine cube) which can be released in to the dishwashing machine during a wash. The receptacle for holding washing detergent may of course also be positioned elsewhere within the dishwashing machine. The dishwashing machine may also include one or more further receptacles for containing dishwashing machine salt and/or rinse aid, for example. 
     A washing cycle of a dishwashing machine  100  includes three basic phases. First, the items to be washed  114  are wetted by the washing mechanism  123 . Next, the items to be washed  114  are cleaned by the washing mechanism  123  spraying them with a mixture of hot water and a dishwashing detergent. Finally, the items to be washed  114  are rinsed with clean water and then air dried by the residual heat in the dishwashing machine or dried by a fan circulating hot air around the washing compartment  104 . 
     The present inventor has realised that occasionally during a washing cycle one or both of the spray arms  124 ,  126  stop rotating. For example, a spray arm  124 ,  126  may come into contact with an item to be washed  114 , which impedes spray arm rotation. This can result in inadequate cleaning of the items to be washed  114  because the water sprayed by the impeded spray arm cannot reach all of the items to be washed  114 . 
       FIGS.  2  to  5    show a spray arm assembly  221  fluidly connected to a pump  254 . The spray arm assembly  221  includes a spray arm  224  mounted on a pipe  225 . The pipe  225  fluidly connects the spray arm assembly  221  to the pump  254  so that the pump  254  can deliver water to the spray arm  224 . The spray arm  224  is mounted to the pipe  225  so that the spray arm  224  can rotate about the pipe  225 . In examples the pipe  225  remains static or fixed while the spray arm  224  rotates about the pipe  225 . To this end the pipe  225  may be considered a stator, and the spray arm  224  may be considered a rotor. A suitable bearing assembly may be provided between the spray arm  224  and the pipe  225  to facilitate the relative rotation. In the example shown in  FIGS.  2  to  5   , the spray arm  224  rotates in a clockwise direction when viewed in plan. In other examples the spray arm  224  may rotate in an anticlockwise direction. 
     The spray arm  224  includes a plurality of spray holes  256 . In this example, each spray hole  256  comprises an aperture. A liquid such as water can be ejected out of each spray hole  256 . The pump  254  can pump water through the pipe  225 , into the spray arm  224 , and out of the spray holes  254  to clean any items to be washed  214 . 
     In in this example, rotation of the spray arm  224  is effected by the force of water being ejected from the spray holes  256 . One or more of the plurality of spray holes  256  may be oriented so as to facilitate such rotation. 
     The pipe  225  includes a barrier portion  258 . The barrier  258  is constructed and arranged to at least partially restrict the flow of water from the pump  254  to a part of the spray arm  224  when the spray arm  224  is in one or more certain orientations as it rotates relative to the pipe  225 . This decreases the flow of water to that part of the spray arm  224  relative to the other part of the spray arm  224 . In this example, the barrier  258  is a separate piece that is attached to an end of the pipe  225 . In another example, the barrier  258  may be integrally formed with the pipe  225 . In one example, the barrier  258  is also constructed and arranged to direct the flow of water from the pump  254  to a part of the spray arm  224  when the spray arm  224  is in a certain orientation as it rotates relative to the pipe  225 . This increases the flow of water to that part of the spray arm  224  relative to the other part of the spray arm  224 . In some examples, the barrier  258  projects substantially upwardly from an end face of the pipe  225 . In some examples, the barrier  258  projects vertically from the end face of the pipe  225 . In some examples the barrier  258  may has a semi-circular shape. In some examples a radius of curvature of the barrier  258  is the same as a radius of curvature of the pipe  225 . In some examples, the barrier  258  is in a fixed position relative to the pipe  225 . 
     In some examples, the pump  254  is a centrifugal pump. The power consumed by the pump  254  is dependent on the volume of water moved by the pump  254 , through the pipe  225 , to the spray arm  224  and out of the spray holes  256 . As mentioned above, according to examples, the barrier  258  at least partially impedes the flow of water from the pump  254  to a part of the spray arm  224  when the spray arm  224  is in certain orientations. Therefore, the flow of water from the pump  254  to the spray arm  224  varies depending on the orientation of the spray arm  224  relative to the pipe  225 . As a result, the power consumed by the pump  254  varies depending on the orientation of the spray arm  224  relative to the pipe  225 . 
     The flow of water from the pump  254 , through the pipe  225  and into the spray arm  224  is represented by the dashed arrows. 
     A controller  234  is provided. The controller  234 , which may be a processor or microprocessor or the like, is configured to monitor the power consumption of the pump  254 . Monitoring the power consumption of the pump  254  allows for rotational information about the spray arm  224  to be determined. This is because, in normal operation when the spray arm  224  is continually rotating as intended, the power consumed by the pump will conform to a particular profile because of the cyclical water flow resistance provided by the barrier  258 . If the power consumption deviates from this profile by more than a predetermined value then the controller  234  determines that the spray arm  224  is not rotating as intended (e.g. the spray arm  224  may have become stuck against an item to be washed  214 ). The predetermined value may be a fixed power consumption (e.g. +/−1 W), or it may be a percentage of the power consumption (e.g. +/−5%). As a consequence, the controller  234  may cause an alert to be output to a user by, for example, displaying an error message on a display, and/or outputting a warning sound through a speaker. In one example, the controller  234  may deactivate the dishwashing machine if it determines that the spray arm  224  is not rotating as expected. 
     As shown, the spray arm  224  has a first side  260  and a second side  262 . In the example shown in  FIGS.  2  and  3   , the first side  260  of the spray arm  224  has the same number of spray holes  256  as the second side  262  of the spray arm  224 . That is in  FIGS.  2  and  3    each side of the spray arm  224  comprises five spray holes  256 . In the example shown in  FIGS.  4  to  10   , the first side  260  of the spray arm  224  has more spray holes  256  than the second side  262  of the spray arm  224 . In the example of  FIGS.  4  to  10    the first side  260  has five spray holes and the second side  262  has three spray holes. 
       FIG.  2    shows the spray arm  224  in a first orientation relative to the pipe  225 , is the pipe  225  being fixed in position. In this first orientation, the barrier  258  restricts the flow of water from the pump  254  to the spray holes  256  of the first side  260  of the spray arm  224 . Therefore, the amount of power consumed by the pump  254  is relatively low because the volume of water conveyed by the pump  254  is relatively low due to the flow restriction provided by the barrier  258 . 
       FIG.  3    shows the spray arm  224  in a second orientation relative to the pipe  225 . In  FIG.  3    the spray arm  224  has rotated 180 degrees relative to  FIG.  2   . In this second orientation, the barrier  258  restricts the flow of water from the pump  254  to the spray holes  256  of the second side  262  of the spray arm  224 . As with the orientation shown in  FIG.  2   , the amount of power consumed by the pump  254  is relatively low because the volume of water conveyed by the pump  254  is relatively low due to the flow restriction provided by the barrier  258 . 
     When the spray arm  224  is in an orientation between the first orientation shown in  FIG.  2    and the second orientation shown in  FIG.  3   , the volume of water conveyed by the pump  254  and ejected by the spray holes increases because the barrier  258  becomes less of a restriction and water can more easily flow to both sides  260 ,  262  of the spray arm  224 . This will be explained in more detail below. 
     Thus where mention is made above to the power consumption of the pump being relatively low (e.g. when in the positions of  FIGS.  2  and  3   ), this may be considered as relatively low compared to when the spray arm  224  is not aligned with the barrier  258  (e.g. when the spray arm  224  is not in the positions of  FIGS.  2  and  3   ). 
     The cyclical nature of the change in the volume of water output through the spray holes  256  as the spray arm  224  rotates results in a cyclical power consumption profile for the pump  254  (mentioned above). The controller  234  can monitor the power consumed by the pump  254  and can cause an alert to be output to the user if the power consumption is not as expected, which may indicate that the spray arm  224  has got stuck and has stopped rotating, or its rotation is impeded. 
     In the example shown in  FIGS.  4  and  5   , the second side  262  of the spray arm  224  has fewer spray holes  256  than the first side  260  of the spray arm  224 . This construction of the spray arm  224  further restricts the output of water that can be conveyed through the second side  262  of the spray arm  224 . This may help provide a more recognisable pump power consumption profile. 
     The operation of the spray arm  224  and the controller  234  will now be described in more detail with respect to the partial cross section plan views shown in  FIGS.  6  to  9   .  FIGS.  6  to  9    show the spray arm  224  as it rotates in a clockwise direction during use of the dishwashing machine in which it is installed. 
       FIG.  6    shows the spray arm  224  in its first orientation as shown in  FIG.  4   . In this position, the volume of water ejected from the first side  260  of the spray arm  224  is V 1  and the volume of water ejected from the second side  262  of the spray arm  224  is V 2 . V 1  is approximately the same as V 2  due to the effect of the barrier  258  impeding water flow to the first side  260  of the spray arm  224  being mitigated by there being fewer spray holes  256  in the second side  262  of the spray arm  224 . In this orientation the power consumed by the water pump  254  in ejecting the water may be considered P 12 . 
       FIG.  7    shows the spray arm  224  in between rotating from its first orientation to its second orientation. In this position, the volume of water ejected from the first side  260  of the spray arm  224  is V 3  and the volume of water ejected from the second side  262  of the spray arm  224  is V 4 . V 3  is larger than V 4  due to there being more spray holes  256  in the first side  260  of the spray arm  224 . In this orientation the power consumed by the water pump  254  in ejecting the water may be considered P 34 . 
       FIG.  8    shows the spray arm  224  in its second orientation as shown in  FIG.  5   . In this position, the volume of water ejected from the first side  260  of the spray arm  224  is V 5  and the volume of water ejected from the second side  262  of the spray arm  224  is V 6 . V 5  is larger than V 6  due to the barrier  258  impeding water flow to the second side  262  of the spray arm  224 , and due to there being more spray holes  256  in the first side  260  of the spray arm  224 . In this orientation the power consumed by the water pump  254  in ejecting the water may be considered P 56 . P 56  is higher than P 12  because in the orientation of  FIG.  8    the barrier  258  only restricts water flow to the second side  262  of the spray arm  224 , which has fewer holes than the first side  260  of the spray arm  224 . However, in the orientation of  FIG.  5   , the barrier  258  impedes water flow to the first side  260  of the spray arm  224 . 
       FIG.  9    shows the spray arm  224  in between rotating from its second orientation to its first orientation. In this position, the volume of water ejected from the first side  260  of the spray arm  224  is V 7  and the volume of water ejected from the second side  262  of the spray arm  224  is V 8 . V 7  is larger than V 8  due to there being more spray holes  256  in the first side  260  of the spray arm  224 . In this orientation the power consumed by the water pump  254  in ejecting the water may be considered P 78 . P 78  is approximately the same as P 34  because in the positions of the spray arm  224  in  FIGS.  7  and  9    the barrier  258  equally restricts water flow to each side  260 ,  262  of the spray arm  224 . 
     Since the volume of water ejected out of the spray arm  224  varies as the spray arm  224  rotates over time, the power consumed by the water pump  254  also varies as the spray arm  224  rotates over time. As such, the power consumption of the pump  254  can be predicted over time. 
       FIG.  10    shows an example of pump power consumption fluctuating over time as the spray arm  224  rotates, between a minimum power consumption when the spray arm  224  is in the position shown in  FIG.  6    and a maximum power consumption when the spray arm is in the position shown in  FIG.  8   . The dishwashing machine  200  may include a data storage for storing information related to the expected power consumption of the pump  254 . For example, the data storage may store expected power consumption information, for example as represented by the graph show in  FIG.  10   . 
     According to examples the controller  234  is configured to monitor the power that is consumed by the pump  254  as the spray arm  224  rotates. In some examples, the controller  234  is configured to cause an alarm to be output to a user if the power consumption deviates from the expected profile shown in  FIG.  10    by more than a predetermined or threshold value (e.g. by more than 5%). The alarm may be a signal to a speaker to output an alert or buzzer sound. In another example, the alarm may be a visual alert output to a display. The alarm may alert or prompt the user to fix the fault e.g. to move the item that is blocking the spray arm  224 . If the power consumption deviates from the expected profile by less than a predetermined value then in some examples the controller  234  takes no action, but continues to monitor the power consumed by the pump  254 . This allows for minor variations in power consumption of the pump to be accounted for, which may not be a result of the spray arm  224  getting stuck on an item to be washed. 
     In another example, the controller  234  is configured to cause an alarm to be output if the power consumption deviates from the expected profile shown in  FIG.  10    for more than a predetermined time period (e.g. ten seconds). 
     In some examples, when the determined power consumption of the pump  254  differs from the expected rate by more than a predetermined threshold value or for more than a predetermined period of time, the controller  234  is configured to halt the washing cycle. Halting the washing cycle may include halting power and/or water to the spray arm(s). In some examples the washing cycle is only resumed after the door of the washing machine has been opened and closed (i.e. indicative that a user has cleared the obstruction), and/or after a certain user input on the user interface  136  (e.g. pressing an “OK” button), and/or after one or more test rotations of the spray arm(s). In some examples the washing cycle may be automatically restarted after it has been determined that an alert state (e.g.) blockage of spray arm, has been cleared. 
     The above example allows for the controller  234  to accurately estimate when the spray arm  224  has been blocked by an obstruction in the dishwashing machine  200 , such as caused by an incorrectly placed item to be washed. The controller  234  can then alert the user so that the user can remove the obstruction. This helps to prevent damage to the spray arm  224  and the water pump  254 , and it also ensures that the cleaning quality of a washing cycle is not compromised by the spray arm  224  being unable to rotate. 
     Reference is made herein to data storage for storing data, such as memory. This may be provided by a single device or by plural devices. Suitable devices include for example a hard disk and non-volatile semiconductor memory. 
     The examples described herein are to be understood as illustrative examples of embodiments of the invention. Further embodiments and examples are envisaged. Any feature described in relation to any one example or embodiment may be used alone or in combination with other features. In addition, any feature described in relation to any one example or embodiment may also be used in combination with one or more features of any other of the examples or embodiments, or any combination of any other of the examples or embodiments. Furthermore, equivalents and modifications not described herein may also be employed within the scope of the invention, which is defined in the claims.