EP3469977B1

EP3469977B1 - Method for selecting washing operation for a dishwasher

Info

Publication number: EP3469977B1
Application number: EP17195633.7A
Authority: EP
Inventors: Irfan KARAZOR
Original assignee: Vestel Elektronik Sanayi ve Ticaret AS
Current assignee: Vestel Elektronik Sanayi ve Ticaret AS
Priority date: 2017-10-10
Filing date: 2017-10-10
Publication date: 2020-06-24
Anticipated expiration: 2037-10-10
Also published as: EP3469977A1; TR201716833A2

Description

The present invention relates to a washing control method according to claim 1 of the present disclosure, and to a dishwasher according to claim 2 of the present disclosure.

Background of the Invention

A dishwasher or a dishwashing machine is a mechanical device for cleaning dishware and cutlery i.e. dishes. The dishwasher cleans by spraying wash water, i.e. cold or hot water mixed with wash detergent, at the dishes. A mix of water and dishwasher detergent, i.e. the wash water is pumped to one or more rotating spray arms, which blast the dishes with the wash water. The wash water washes the contaminants i.e. the leftover food particles adhered to the dishes being washed, off the dishes and the wash water along with the contaminants collects in a dishwasher compartment, i.e. a sump, generally located at the bottom of the dishwasher beneath the space where the dishes are stacked for washing. In a complete washing operation for a given set of dishes being washed, several such spraying sessions from the spray arms, generally referred to as washing cycles or wash cycles are required to clean the dishes to a desired degree. The complete washing operation generally includes, besides the multiple washing cycles, one or more rinse cycles, and a drying cycle.
For achieving the multiple washing cycles during the complete washing operation, generally, the wash water along with the contaminants, hereinafter referred together to as the wash water, is either circulated back from the dishwasher compartment to the spray arms for reuse in a subsequent washing cycle of the same dishes or is drained out off the dishwasher and fresh water is added into the dishwasher for the subsequent washing cycle. Whether to drain the wash water off the dishwasher or to reuse the wash water for a subsequent washing cycle of the same dishes depends on the suitability of the wash water for reuse. The suitability of the wash water that has been used in a previous washing cycle for the dishes depends on the amount of the contaminants present in the wash water from the previous washing cycle of the complete washing operation. If the wash water from the previous one or more washing cycles during the complete washing operation is suitably clean, then the same wash water is circulated, by a circulation pump driven by a motor, from the dishwasher compartment to the rotating spray arms of the dishwasher via one or more circulation hoses that fluidly connect the dishwasher compartment to the spray arms of the dishwasher. However, if the wash water from the previous one or more washing cycles during the complete washing operation is not suitably clean or in other words is dirty then the wash water is drained off the dishwasher.
The suitability of the wash water for reuse in a subsequent washing cycle after one or more previous washing cycles is conventionally determined from turbidity of the wash water. If the turbidity of wash water exceeds a predetermined, i.e. threshold turbidity, the wash water is deemed to be unfit for a subsequent washing cycle and is therefore drained off the dishwasher. Such an approach is conventionally known and an example of such an approach is disclosed in United States Patent Application number 20080128001 A1 titled Washing control apparatus and method of dish washing machine. The turbidity sensors measure turbidity of the wash washer generally by measuring optical properties of the wash water such as light scattering properties of the wash water. The amount of light scattered is influenced by many aspects of the particles i.e. the contaminants suspended in the wash water for example color, shape, and reflectivity. Thus, different wash waters having same amount of contaminants present may vary in their turbidity measurements depending on color or reflectivity of the contaminants, and thus one of the wash water samples may be concluded to be suitable for use in subsequent washing cycle whereas another wash water sample may be concluded to be unsuitable for use in subsequent washing cycle, albeit both the wash water samples have same number of contaminants. Furthermore, the turbidity may also be influenced by color of the detergent used. Also, due to the fact that heavier contaminants may settle quickly and may not contribute to the turbidity reading, the turbidity readings may change depending on location from which the wash water was tested.
Hence, there exists a need for a technique for selecting or controlling washing operation that is independent of turbidity measurements of the wash water.
Further, PCT Patent Application No. WO2017059896 discloses a method and appliance for controlling a circulation pump. The appliance for washing and rinsing goods comprises a circulation pump, a sensing arrangement arranged to measure an indication of circulation pump pressure or process water flow rate through the circulation pump, and a controller arranged to control operating speed of the circulation pump. The controller is further arranged to detect that the indicated circulation pump pressure or process water flow rate through the circulation pump is insufficient and gradually reduce operating speed of the circulation pump until the circulation pump pressure or the process water flow rate through the circulation pump is at a sufficient operational level. Further, a pump control scheme is applied which closely tracks falling pressure or reduced flow rate of the pump in order to restore the pressure/flow rate at a satisfactory level.
Furthermore, US Patent Application No. US20110114132 discloses a ware washer, which is designed as a programmable machine or as a conveyor ware washer, which has at least one pump, at least one line system connected to the pump, and at least one nozzle system connected to the line system and having at least one nozzle, a liquid being supplied at least intermittently to the at least one nozzle via the line system. A sensor device connected to a control device is provided for detecting a profile of the volumetric flow rate of the liquid in the line system and for comparing the detected flow rate profile with a predetermined flow rate profile. The control device is designed, in the event of a deviation of the detected flow rate profile from the predetermined flow rate profile, automatically either to carry out a regulating action on the operation of the ware washer as a function of the size and the time gradient of a difference between the predetermined flow rate profile and the detected flow rate profile or to issue a fault warning via an optical and/or acoustic interface or to issue a fault warning to a remote maintenance station via a remote control interface.

Object of the Invention

It is therefore an object of the present invention to provide an efficient technique for selecting or controlling washing operation in a dishwasher, preferably a washing control method and a washing control apparatus for selecting washing operation for a dishwasher.

Summary of the Invention

The aforementioned object is achieved by a washing control method according to claim 1 of the present invention, which presents a first aspect of the present technique. The washing control method for the dishwasher, hereinafter also referred to as the method, is used in a dishwasher having a motor to drive a circulation pump for circulating wash water through a circulation hose from a dishwasher compartment towards spray arms of the dishwasher. In the method according to the invention, a flow rate of the wash water is detected by a flow meter. The flow rate is detected of the wash water flowing in the circulation hose of the dishwasher while washing is performed using the wash water, i.e. when the wash water is being circulated into the circulation hose from the dishwasher compartment. Thereafter in the method, a washing operation based on the detected flow rate of the wash water is determined by using a control unit. The washing operation may be either to reuse the wash water for a subsequent washing cycle or to drain off the wash water and optionally to introduce fresh water to replace the wash water so drained off.
The flow rate measured or detected indicates a viscosity of the wash water which in turn indicates the number of contaminants suspended or dissolved in the wash water. When the amount of the contaminants in the wash water is high the wash water is more viscous than when the amount of the contaminants in the wash water is low, and thus a flow rate of the wash water through the circulation hose is lower when the wash water has more contaminants than a flow rate of the wash water through the circulation hose when the wash water has lesser contaminants. Thus, the control unit selects or determines the washing operation i.e. whether to re-circulate the wash water for subsequent washing cycle or to drain off the wash water, based on the flow rate of the wash water through the circulation hose of the dishwasher. Thus, the method of the present technique is independent of turbidity measurement of the wash water which might not be measured in a correct or efficient way.
The washing control method according to the invention comprises the determining, by the control unit, of the washing operation based on the detected flow rate of the wash water further includes:

determining a motor speed corresponding to the flow rate detected by the flow meter;
comparing the detected flow rate to a predetermined threshold reference flow rate for the wash water corresponding to the motor speed so determined, and
selecting one of a first washing operation of the dishwasher when the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate and a second washing operation of the dishwasher when the detected flow rate of the wash water exceeds the predetermined threshold reference flow rate.

The flow rate of the wash water through the circulation hose is dependent on the viscosity of the wash water and on a speed of the motor driving the circulation pump pumping the wash water into the circulation hose. The present embodiment of the method factors in the motor speed at the time when the flow rate of the wash water is detected or determined by the flow meter. The flow rate of the wash water varies proportionately to the motor speed. For different phases of the complete washing operation, and particularly for different phases of a given washing cycle different motor speeds are pre-set, and thus the motor speeds are predetermined i.e. the motor speed at a given instance of time during the washing cycle is known. The invention envisages a reference table that may be stored in a memory unit of the dishwasher or otherwise provided to the control unit, having different motor speeds and corresponding predetermined threshold reference flow rates indicative of suitability of the wash water for reuse in subsequent washing cycle. Therefore, by determining the flow meter output, i.e. the flow rate, at a given motor speed and comparing it with the predetermined threshold reference flow rate at the same motor speed, one of the following may be concludes and the washing operation may be proceeded accordingly:

(a) determined flow meter output, i.e. the determined or detected flow rate of the wash water is greater than the predetermined threshold reference flow rate, i.e. the wash water is flowing at high flow rate and thus the viscosity of the wash water is low and therefore the wash water can be used further to continue washing i.e. the wash water may be used in a subsequent washing cycle; or
(b) determined flow meter output, i.e. the determined or detected flow rate of the wash water is equal to or less than the predetermined threshold reference flow rate, i.e. the wash water is flowing at lower flow rate and thus the viscosity of the wash water is high and therefore the wash water cannot be used further to continue washing i.e. the wash water needs to be drained off the dishwasher, and optionally replaced by adding fresh water or more water.

The method of the present invention includes draining of the wash water if the first washing operation of the dishwasher is selected i.e. when the wash water is determined to be unsuitable for use in the subsequent washing cycle owing to the detected flow rate of the wash water through the circulation hose; and continuing washing using the wash water if the second washing operation of the dishwasher is selected, i.e. when the wash water is determined to be suitable for use in the subsequent washing cycle owing to the detected flow rate of the wash water through the circulation hose.
The aforementioned objective is also achieved by a dish washer according to claim 2, which presents a second aspect of the present technique. As aforementioned the washing control apparatus of the present technique is used in a dishwasher that has a motor to drive a circulation pump for circulating wash water through a circulation hose from a dishwasher compartment towards spray arms of the dishwasher. The washing control apparatus includes a flow meter and a control unit. The flow meter detects a flow rate of wash water in the circulation hose of the dishwasher while washing is performed using the wash water i.e. when the wash water is being circulated into the circulation hose from the dishwasher compartment. The control unit determines a washing operation based on the detected flow rate of the wash water.
As aforementioned, the washing operation may be either to reuse the wash water for a subsequent washing cycle or to drain off the wash water and optionally to introduce fresh water to replace the wash water. Thus, the control unit selects or determines the washing operation i.e. whether to re-circulate the wash water for subsequent washing cycle or to drain off the wash water, based on the flow rate of the wash water through the circulation hose of the dishwasher.
According to the invention, the control unit determines a motor speed corresponding to the flow rate detected by the flow meter. The control unit thereafter compares the detected flow rate to a predetermined threshold reference flow rate for the wash water corresponding to the motor speed so determined. The control unit, finally, determines the washing operation by selecting between a first washing operation of the dishwasher when the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate and a second washing operation of the dishwasher when the detected flow rate of the wash exceeds the predetermined threshold reference flow rate.
As aforementioned for the first aspect of the present technique, the flow rate of the wash water through the circulation hose is dependent on the viscosity of the wash water and on the speed of the motor driving the circulation pump pumping the wash water into the circulation hose. The control unit factors in the motor speed at the time when the flow rate of the wash water is detected or determined by the flow meter. The apparatus of the present technique envisages a reference table that may be stored in a memory unit of the dishwasher or otherwise provided to the control unit, having different motor speeds and corresponding predetermined threshold reference flow rates indicative of suitability of the wash water for reuse in subsequent washing cycle. Therefore, from the flow meter output, i.e. the flow rate, at a given motor speed, the control unit by comparing the flow rate with the predetermined threshold reference flow rate at the same motor speed, is able to conclude whether the wash water may be used in a subsequent washing cycle or the wash water needs to be drained off the dishwasher, and optionally replaced by adding fresh water or more water.
According to the invention, the control unit is configured to initiate a drainage operation of the wash water if the first washing operation of the dishwasher is selected or to continue washing using the wash water if the second washing operation of the dishwasher is selected.
In the present technique, the flow meter is positioned at the circulation hose that fluidly connects the dishwasher compartment and at least one of the spray arms of the dishwasher, i.e. in other words the dishwasher compartment and the at least one of the spray arms of the dishwasher are in fluid communication via the circulation hose.
Further benefits, goals and features of the present invention will be described by the following specification of the attached figures, in which components of the invention are exemplarily illustrated. Components of the system and the method according to the invention, which match at least essentially with respect to their functions, can be marked with the same reference sign, wherein such components do not have to be marked or described in all figures.
The invention is just exemplarily described with respect to the attached figures in the following.

Brief Description of the Drawings

Fig. 1 schematically represents an exemplary embodiment of a washing control apparatus of the present technique,
Fig. 2 is a flow chart depicting a washing control method of the present technique, and
Fig. 3 schematically represents an exemplary embodiment of a dishwasher of the present technique; in accordance with aspects of the present technique.

Detailed Description of the Drawings

It may be noted that in the present disclosure, the terms 'first', 'second', 'third', etc are used herein only to facilitate discussion and carry no particular temporal or chronological significance unless otherwise indicated.
Fig. 1 depicts a washing control apparatus 1 that is used in a dishwasher 10 schematically depicted in a side sectional view in Fig. 3.
As shown in FIG. 1, the dishwasher 10 includes a machine body 11 having a washing space defined therein and a door 12 to open and close the front part of the dishwasher 10 through which one or more dishes 5 that are to be cleaned are stacked or placed in the washing space of the dishwasher 10. Generally, at one side of the door 12 is mounted a drying fan 14 to dry the dishes 5 after being cleaned, usually as a last phase or cycle of a complete washing operation of the dishes 5. The complete washing operation generally includes multiple washing cycles of the dishes 5, one or more rinse cycles, and a drying cycle. The dishwasher 10 includes an input panel 130 using which a user of the dishwasher 10 may select different washing programs that are to be performed by the dishwasher 10 during the complete washing operation.
In the dishwasher 10 is mounted a washing tub 20, in which a plurality of dish baskets 22 to receive dishes 5, racks 24 to slidably support the dish baskets 22, and an upper spray arm 26a also referred to as the upper injection nozzle 26a, a middle spray arm 26b also referred to as the middle injection nozzle 26b, and a lower spray arm 26c also referred to as the lower injection nozzle 26c are mounted. Specifically, the upper spray arm 26a, the middle spray arm 26b, and the lower spray arm 26c are mounted above and below the dish baskets 22 to inject wash water in form of jets 9. It may be noted that the number of spray arms 26a, 26b, 26c depicted in Fig. 3 are for exemplary purposes only and in other embodiments (not shown) of the dishwasher 10, a number of the spray arms 26a, 26b, 26c may be more than or less than the number of the spray arms 26a, 26b, 26c depicted in the example of Fig. 3.
The upper spray arm 26a and the middle spray arm 26b are fluidly connected with a dishwasher compartment 42 or a sump 42 i.e. a hollow or depression or a container in which the wash water collects after impacting and falling off the dishes 5, via a circulation hose 28a, also referred to as a first supply pipe 28a. The lower spray arm 26c is fluidly connected to the dishwasher compartment 42 via a circulation hose 28b, also referred to as a second supply pipe 28b. The phrase 'fluidly connected' as used herein means is/are in fluid communication with, i.e. in other words, the wash water can flow from the dishwasher compartment 42, also referred to as the dishwasher chamber 42, to the spray arms 26a, 26b, 26c via the circulation hoses 28a, 28b.
At the bottom of the washing tub 20 is mounted a heater 30 to heat the wash water. Specifically, the heater 30 is disposed in a heater receiving groove 32 formed at the bottom of the washing tub 20.
A space 40, within the machine body 11 at the bottom of the washing tub 20, houses the dishwasher compartment 42. Within the space 40 is present a circulation pump 46, also referred to as a washing pump 46, to pump the wash water from the dishwasher compartment 42 into the circulation hoses 28a, 2b. At one side of the dishwasher compartment 42 are mounted a drainage pump 48 and a drainage pipe 50 to drain off the wash water, when desired or when so determined by the washing control apparatus 1, i.e. to release the contaminated wash water to the outside of the dishwasher 10. The circulation pump 46 is driven by a motor 120, also referred to as a drive unit 120. The motor 120 also optionally drives the drainage pump 48 and/or the fan 14.
As shown in Fig. 1 and Fig. 3, the dishwasher 10 includes a flow meter 105 and a control unit 110 that together form the washing control apparatus 1 of the present technique. The flow meter 105 is positioned at the circulation hose 28a that fluidly connects the dishwasher compartment 42 and the spray arms 26a, 26b of the dishwasher 10. In another embodiment (not shown) the flow meter 105 is positioned at the circulation hose 28b that fluidly connects the dishwasher compartment 42 and the spray arm 26c of the dishwasher 10.
The flow meter 105 is a device that measures a flow rate or a rate of flow i.e. quantity of the wash water per time unit moving through the circulation hose 28a, 28b at which the flow meter 105 is installed. The flow meter 105 is also referred to as a flow gauge, a flow indicator, or a liquid meter. The flow meter 105 detects a flow rate of the wash water in the circulation hose 28a of the dishwasher 10 when the wash water is being circulated via the circulation hose 28a from the dishwasher compartment 42 towards the spray arms 26a, 26b. The control unit 110, for example a processor, determines a washing operation based on the detected flow rate of the wash water. Fig. 2 presents a washing control method 500, hereinafter also referred to as the method 500, of the present technique and hereinafter Fig. 2 in combination with Figs. 1 and 3 has been used to further explain functioning of the flow meter 105 and the control unit 110 of the washing control apparatus 1.
Within the method 500 according to the invention, in a step 510 a flow rate of the wash water is detected by the flow meter 105. As aforementioned the flow rate is detected of the wash water flowing in the circulation hose 28a of the dishwasher 10 from the dishwasher compartment 42 towards the spray arms 28a, 28b. Thereafter in the method 500, in a step 520 a washing operation based on the detected flow rate of the wash water is determined by the control unit 110.
The washing operation may be either to reuse the wash water for a subsequent washing cycle or to drain off the wash water and optionally to introduce fresh water to replace the wash water. The flow rate measured or detected by the flow meter 105 indicates a viscosity of the wash water, which in turn indicates the amount of contaminants suspended or dissolved in the wash water from the dishes 5. As aforementioned, a flow rate of the wash water through the circulation hose 28a is lower when the wash water has more contaminants than a flow rate of the wash water through the circulation hose 28a when the wash water has lesser contaminants. Thus, the control unit 110 selects or determines the washing operation i.e. whether to re-circulate the wash water for subsequent washing cycle or to drain off the wash water, based on the flow rate of the wash water through the circulation hose 28a of the dishwasher 10.
In an embodiment of the method 500, the step 520 further includes:

a step 522 of determining a motor speed, a speed of the motor 120, corresponding to the flow rate detected by the flow meter 105;
a step 524 of comparing the detected flow rate to a predetermined threshold reference flow rate for the wash water corresponding to the motor speed so determined, and
a step 526 of selecting one of a first washing operation of the dishwasher 10 when the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate and a second washing operation of the dishwasher 10 when the detected flow rate of the wash water exceeds the predetermined threshold reference flow rate.

The flow rate of the wash water through the circulation hose 28a is dependent on the viscosity of the wash water and on a speed, i.e. rotations per minute, of the motor 120 driving the circulation pump 46 pumping the wash water into the circulation hose 28a. The flow rate of the wash water varies proportionately to the motor speed of the motor 120. A reference table or list is provided to or stored in the control unit 110 that has stored therein different motor speeds of the motor 120 and corresponding predetermined threshold reference flow rates indicative of suitability of the wash water for reuse in subsequent washing cycle. The control unit 110 receives the flow meter 105 output, i.e. the flow rate of the wash water through the circulation hose 28a, at a given motor speed and compares the flow rate with the predetermined threshold reference flow rate for the same motor speed.
In another embodiment of the washing control apparatus 1, the control unit 110 determines a motor speed corresponding to the flow rate detected by the flow meter 105. The control unit 105 checks for the motor speed at a time when the flow meter signal is received by the control unit 110 from the pre-set motor speeds available to the control unit 110. The control unit 110 thereafter compares the detected flow rate to the predetermined threshold reference flow rate for the wash water corresponding to the motor speed so determined. The control unit 110, finally, determines the washing operation by selecting between a first washing operation of the dishwasher 10 when the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate and a second washing operation of the dishwasher 10 when the detected flow rate of the wash exceeds the predetermined threshold reference flow rate.
The first washing operation, i.e. when the when the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate, indicates a washing operation wherein the wash water is not to be used in the subsequent washing cycle. The control unit 110 thus initiates a drainage operation of the wash water i.e. when the first washing operation of the dishwasher is selected, for example by driving the drainage pump 48 to exit the water through the drainage pipe or hose 50.
The second washing operation, i.e. when the when the detected flow rate of the wash water exceeds the predetermined threshold reference flow rate, indicates a washing operation wherein the wash water is to be used in the subsequent washing cycle. The control unit 110 thus initiates a subsequent washing cycle with the wash water i.e. when the second washing operation of the dishwasher is selected, for example by driving the circulation pump 46 to pump the wash water through the circulation hoses 28a, 28b and subsequent ejection of the wash water in form of the jets 9 from the spray arms 26a, 26b, 26c 50.
Thus, as shown in Fig. 2 the method 500 after the step 520 either proceeds to a step 530 in which the wash water is drained off the dishwasher 10 if the first washing operation of the dishwasher 10 is selected by the control unit 110 or proceeds to a step 540 in which the washing of the dishes 5 Is continued using the wash water if the second washing operation of the dishwasher 10 is selected by the control unit 110.
Thus, a washing control technique for a dish washer 10 is presented according to the invention. The dishwasher 10 includes a motor 120 driving a circulation pump 46 for circulating wash water through a circulation hose 28a, 28b from a dishwasher compartment 42 towards spray arms 26a, 26b, 26c, a control unit 110, and a flow meter 105 for detecting a flow rate of the wash water in the circulation hose 28a while washing is performed using the wash water. A washing operation based on the detected flow rate of the wash water is determined by the control unit 110. The flow rate indicates a viscosity of the wash water, which in turn indicates amount of contaminants in the wash water. Thus, from the flow rate the control unit 110 determines whether to re-circulate the wash water for subsequent washing cycle or to drain the wash water off the dishwasher 10.

List of reference signs

1: washing control apparatus
5: dishes
9: jets
10: dishwasher
11: machine body
12: door
14: drying fan
20: washing tub
22: dish baskets
24: racks
26a: upper spray arm
26b: middle spray arm
26c: lower spray arm
28a: circulation hose
28b: circulation hose
30: heater
32: heater receiving groove
40: space
42: dishwasher compartment
46: circulation pump
48: drainage pump
50: drainage pipe
105: flow meter
110: control unit
120: motor
130: input panel
500: washing control method
510: detecting a flow rate of the wash water by the flow meter
520: determining a washing operation by the control unit
522: determining a motor speed
524: comparing the detected flow rate to a predetermined threshold reference flow rate
526: selecting one of a first washing operation and a second washing operation
530: draining the wash water off the dishwasher
540: continued washing of the dishes using the wash water

Claims

A washing control method (500) for a dishwasher (10), the dishwasher (10) having a motor (120) to drive a circulation pump (46) for circulating wash water through a circulation hose (28a, 28b) from a dishwasher compartment (42) towards one or more spray arms (26a, 26b, 26c) of the dishwasher (10), the washing control method (500) comprising:
- detecting (510), by a flow meter (105), a flow rate of the wash water in the circulation hose (28a) of the dishwasher (10) while washing is performed using the wash water; and

- determining (520), by a control unit (110), a washing operation based on the detected flow rate of the wash water,
wherein determining (520), by the control unit (110), the washing operation based on the detected flow rate of the wash water comprises:
- determining (522) a motor speed corresponding to the flow rate detected by the flow meter (105);

- comparing (524) the detected flow rate to a predetermined threshold reference flow rate for the wash water corresponding to the motor speed so determined, and

- selecting (526) one of a first washing operation of the dishwasher (10) if the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate and a second washing operation of the dishwasher (10) if the detected flow rate of the wash water exceeds the predetermined threshold reference flow rate,
characterized by

- draining (530) of the wash water if the first washing operation of the dishwasher (10) is selected, and

- continuing (540) washing using the wash water if the second washing operation of the dishwasher (10) is selected.
A dishwasher (10) comprising a washing control apparatus (1), the dishwasher (10) having a motor (120) to drive a circulation pump (46) for circulating wash water through a circulation hose (28a, 28b) from a dishwasher compartment (42) towards one or more spray arms (26a, 26b, 26c) of the dishwasher (10), the washing control apparatus (1) comprising:
- a flow meter (105) configured to detect a flow rate of the wash water in the circulation hose (28a) of the dishwasher (10) while washing is performed using the wash water; and

- a control unit (110) configured to determine a washing operation based on the detected flow rate of the wash water,
wherein the control unit (110) is configured:
- to determine a motor speed corresponding to the flow rate detected by the flow meter (105);

- to compare the detected flow rate to a predetermined threshold reference flow rate for the wash water corresponding to the motor speed so determined, and

- to determine the washing operation by selecting one of a first washing operation of the dishwasher (10) if the detected flow rate of the wash water does not exceed the predetermined threshold reference flow rate and a second washing operation of the dishwasher (10) if the detected flow rate of the wash water exceeds the predetermined threshold reference flow rate,
characterized in that
the control unit (110) is further configured:
- to initiate a drainage operation of the wash water if the first washing operation of the dishwasher (10) is selected; and

- to continue washing using the wash water if the second washing operation of the dishwasher (10) is selected.
The dishwasher (10) according to claim 2, wherein the flow meter (105) is positioned at the circulation hose (28a, 28b) fluidly connecting the dishwasher compartment (42) and at least one of the spray arms (26a, 26b, 26c) of the dishwasher (10).