EP3393325B1

EP3393325B1 - A dishwasher and a control method thereof

Info

Publication number: EP3393325B1
Application number: EP15813873.5A
Authority: EP
Inventors: Ozgur OZTURK; Bulent Kucukcoskun; Serkan DEMIR; Engin Dik
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2015-12-22
Filing date: 2015-12-22
Publication date: 2019-08-07
Anticipated expiration: 2035-12-22
Also published as: EP3393325A1; WO2017108093A1; PL3393325T3; TR201618937A2

Description

This invention relates to a dishwasher whose washing performance has been improved and to a control method thereof.
It is known that the performance of a dishwasher depends on the conditions of use and on the correct functioning of the circulation pump which draws water from the sump, arranged in the lower section of the wash tub, to turn it back to the wash tub.
Depending on the conditions of use, in fact, the circulation pump may not draw and recirculate the nominal amount of water, during the washing or rinsing process.
The cleaning and rinsing performance of the dishwasher could hence be impaired by the recirculation of an insufficient amount of water, which can also lead to the formation of unpleasant smells in the wash tub.
Moreover, the functioning of the pump when the flow of washing/rinsing liquid has dropped below a certain level can lead to damages to the pump, due to its dry running condition.
Dishwashers have been developed which allow to control the correct functioning of the circulation pump and, hence, the correct performing of the washing or rinsing process.
An example of such a dishwasher is given in the international patent application n. WO 2005/089621 . The dishwasher therein described comprises a control card tracing the current drawn by the circulation pump and determining consequently the alteration of the conditions of use of the dishwasher, such as clogging of filter, increase in viscosity or in the amount of foam of the water, blocking of rotor or sticking of the pump felt, which affect how the current drawn from the network by the pump motor changes over the time. The identified problem is solved by changing the rpm of the circulation pump and/or its direction of rotation.
The control method proposed for such dishwasher, however, is particularly complex. Moreover, the only adjustment of the functioning parameters of the pump cannot ensure the restoration of the optimal conditions of use of the dishwasher.
An objective of the present invention is to provide a dishwasher and a control method thereof which, once it has been detected that the circulation pump does not draw and recirculate the nominal amount of water, allows to restore the optimal conditions of use of the dishwasher, removing the causes that are affecting the washing or rinsing performance negatively.
This objective has been achieved by the dishwasher as defined in claim 1 and by the control method thereof as defined in claim 3. Further achievements have been attained by the subject-matters respectively defined in the dependent claims.
The dishwasher of the present invention comprises a control unit which is programmed to command the performance of three operational steps upon the detection of a functioning problem of the circulation pump and in particular upon detection of dry running conditions of the circulation pump, which steps are: increasing the rpm of the circulation pump, resetting the position of the valve and drawing a specific further amount of water into the hydraulic circuit from the external source of water. These steps ensure that the optimal amount of washing liquid is allowed to recirculate through the wash tub, either removing the cause that is preventing part of the washing liquid from recirculating or restoring the correct amount of recirculating liquid.
In an embodiment, the dishwasher further comprises a timer for measuring a time interval during which the circulation pump is deactivated to cool down.
It is an object of the invention also a control method for a dishwasher comprising determining that the circulation pump is encountering a functioning problem, generating an error signal for the control unit associated with the functioning problem of the circulation pump and performing a restoring cycle, which comprises the three operational steps specified above.
In a version of the method, the restoring cycle further comprises a step for controlling if the correct functioning of the circulation pump has been restored, which step follows at least one of the three operational steps performed in order to remove the malfunctioning cause.
In a further version, in the restoring cycle, the rpm increasing step, the valve resetting step and the additional water drawing step are all performed before the circulation pump checking step.
In an alternative version, in the restoring cycle, the rpm increasing step, the valve resetting step and the additional water drawing step are performed in a sequence and after each of them, the circulation pump checking step is performed.
According to a version of the control method, the restoring cycle is repeated for a maximum number of repetitions, set by the producer, if the correct functioning of the circulation pump is not before restored.
According to a further version of the method, if the correct functioning of the circulation pump is not restored after the restoring cycle has been repeated for the maximum number of repetitions, it is envisaged to deactivate the circulation pump for an interval of time which is preset by the producer and which is measured by the timer of the dishwasher, in order to allow the circulation pump to cool down. Once the interval of time has passed, the restoring cycle is repeated until the correct functioning of the circulation pump has been restored or until the maximum number of repetitions has been reached again.
In a version of the method, the sequence of the restoring cycle repeated until the maximum number of repetitions is reached and the consequent deactivation of the circulation pump for the preset interval of time, is repeated until a maximum number of reiterations has been reached, if not previously interrupted by the restoring of the correct functioning conditions of the circulation pump.
According to a version, the method comprises a further step of generating an alarm signal to inform the user of the functioning problem of the circulation pump, if the correct functioning of the circulation pump has not been restored after the maximum number of reiterations has been reached.
Additional advantages of the dishwasher and of the control method of the present invention will become apparent with the detailed description of the embodiments with reference to the accompanying drawings in which:

Figure 1 - is the schematic view of a dishwasher.
Figure 2 - is a flow chart of a control method of a dishwasher according to the present invention.

Elements shown in figures are numbered as follows.

1. Dishwasher
2. Wash tub
3. Hydraulic circuit
4. First rotatable spray arm
5. Second rotatable spray arm
6. First rack
7. Second rack
8. Sump
9. Filter
10. Duct
11. Circulation pump
12. Valve
13. Control unit
14. Intake valve
15. Drain pump
16. Timer

The dishwasher 1 comprises a wash tub 2 in which the dishes to be washed, i.e. dishes, kitchenware, tableware, crockery etc. to be washed, are placed, and a hydraulic circuit 3, connectable to an external source of water, for circulating washing liquid through the wash tub 2.
The hydraulic circuit 3 has at least a first rotatable spray arm 4 and a second rotatable spray arm 5 which are arranged in the wash tub 2 to spray the dishes with the washing liquid. More in detail, according to a preferred embodiment illustrated in Figure 1, the dishwasher 1 comprises a first rack 6 and a second rack 7 which are extendably disposed into the wash tub 2 one above the other to be loaded by the user with the dishes to be washed and which are associated respectively with the first rotatable, lower, spray arm 4 and with the second rotatable, upper, spray arm 5.
The hydraulic circuit 3 further comprises a sump 8 which is arranged in the lower section of the wash tub 2 to collect the washing liquid that has been sprayed on the dishes during washing operation, i.e. during the washing and rinsing steps that are performed in order to clean the dishes, a filter 9 arranged in the sump 8 for preventing the dirt from getting into the circulation during washing, which dirt would decrease the effectiveness of washing, and a duct 10 for conveying the filtered washing liquid from the sump 8 to the first spray arm 4 and the second spray arm 5.
The dishwasher 1 comprises a circulation pump 11, driven by an electric motor with variable rpm and arranged on the hydraulic circuit 3 downward of the sump 8, with respect to the flowing direction of the washing liquid in the hydraulic circuit 3, to draw the washing liquid from the sump 8 toward the first and second spray arms 4 and 5 through the duct 10. The dishwasher 1 comprises also a valve 12, in particular a diverter valve, arranged on the hydraulic circuit 3 downward of the circulation pump 11, with respect to the flowing direction of the washing liquid in the hydraulic circuit 3, for allowing to selectively deliver the washing liquid to the first spray arm 4 and/or to the second spray arm 5, and a control unit 13 connected to the hydraulic circuit 3, to the circulation pump 11 and to the valve 12, for controlling their functioning during washing operation. More in detail, the control unit 13 controls the activation/deactivation of the circulation pump 11 and of the valve 12 and it controls the intake of water in the hydraulic circuit 3. In particular the hydraulic circuit 3 advantageously comprises an intake valve 14, to allow or to interrupt the intake of water from the external source.
The dishwasher 1 further comprises a drain pump 15, associated to the hydraulic circuit 3 for draining the water collected in the sump 8 at the end of the washing operation out of the dishwasher 1.
According to the invention, the control unit 13 is programmed to command the increasing of the rpm of the circulation pump 11, the resetting of the position of the valve 12 and the drawing of a further amount of water into the hydraulic circuit 3 from the external source of water upon the detection of a functioning problem of the circulation pump 11.
In particular, the control unit 13 of the dishwasher 1 according to the invention is programmed to overcome the malfunctioning of the circulation pump 11 deriving from dry run conditions, which occur when the amount of washing liquid drawn by the circulation pump 11 is less than the amount envisaged for the standard functioning conditions of the pump. Generally the dry run conditions of the pump are associated to a greater amount of current being drawn by the motor of the pump without however a correspondent increase of the rpm of the pump.
By commanding the performance of the above mentioned operating steps, the control unit 13 allows to overcome the causes that can lead to an insufficient amount of washing liquid being drawn by the pump 11 and recirculating through the wash tub 2. More specifically, by commanding the increase of the rpm of the circulation pump 11, the control unit 13 favors the removing of possible clogging of the filter 9 that would not allow a sufficient amount of washing liquid to reach the circulation pump 11.
By commanding the reset of the position of the valve 12, i.e. by commanding the valve 12 to be reenergized in order to reach the selected position, the control unit 13 allows to ensure that all the washing liquid recirculating in the hydraulic circuit 3 is actually reaching the selected spray arm, thus avoiding that a possible wrong positioning of the valve 12 could entail the dispersion of part of the washing liquid.
By commanding the drawing of a further specific amount of water, for instance preset by the producer or set by the control unit 13 depending on the detected functioning conditions of the pump 11, into the hydraulic circuit 3 from the external source of water, i.e. more specifically by commanding the opening of the intake valve 14, the control unit 13 allows to restore the optimal amount of washing liquid recirculating in the hydraulic circuit 3, for instance in the case in which one or more dishes or pieces of kitchenware or tableware not optimally disposed by the user in the wash tub 2 collect a certain amount of the washing liquid sprayed onto them, thus preventing such amount of the washing liquid from reaching the sump 8 and from recirculating through the wash tub 2.
Therefore, the control unit 13 of the dishwasher 1 according to the invention is programmed to remove the causes of the malfunctioning of the circulating pump 11 ensuring the restoration of the optimal functioning conditions of the latter and thus improving the cleaning efficiency of the dishwasher and avoiding the formation of bad odors.
In an embodiment in accordance with the flow chart illustrated in Figure 2, the circulation pump 11 is designed to create an error signal when encountering a functioning problem, i.e. when at least one of its functioning parameters depart of a certain degree, preset by the producer, from its nominal functioning parameters values, and to send such error signal to the control unit 13, which is programmed to respond to such error signal by commanding the performance of the three operational steps above specified.
In a different embodiment, the control unit 13 is programmed to detect the variations of the functioning parameters of the circulation pump 11, like for instance in particular the variations on the current drawn from the network by the motor of the pump 11 for detecting a functioning problem of the circulation pump 11. In this embodiment, the control unit 13 is programmed to command the performance of the three operational steps above specified once it has established that the variations of the functioning parameters of the circulation pump 11 are to be associated to a malfunctioning of the pump 11.
According to an embodiment, the dishwasher 1 further comprises a timer 16 aimed to measure a time interval during which the circulation pump 11 is deactivated to allow it to cool down.
It is an object of the present invention also a control method for a dishwasher 1 as above described.
The control method according to the invention, which is governed by the control unit 13, comprises, after the starting of the circulation pump 11, a step of determining that the circulation pump 11 is encountering a functioning problem.
As above specified this step can be performed by the circulation pump 11 itself, designed to create an error signal when encountering a functioning problem, or by the control unit 13, programmed to monitor the functioning parameters of the circulation pump 11 and to detect their possible variations.
The control method further comprises a step of generating an error signal associated with the functioning problem of the circulation pump 11 for the control unit 13.
More in detail, in the embodiment where the circulation pump 11 is designed to detect the occurring of a functioning problem, the error signal is created by the circulation pump 11 and sent by the latter to the control unit 13, as reported in Figure 2.
Differently, in the embodiment where the control unit 13 is programmed to monitor the functioning of the circulation pump 11 and to detect any malfunctioning of it, the error signal is the signal generated by the control unit 13 itself and that allows the latter to command the further operational steps aimed to remove the causes of the malfunctioning of the circulation pump 11.
The control method further comprises a restoring cycle, which includes an rpm increasing step for increasing the rpm of the circulation pump 11, by command of the control unit 13, a valve resetting step for resetting the position of the valve 12, by command of the control unit 13 and an additional water drawing step for drawing a further specified amount of water into the hydraulic circuit 3 from the external source of water, by command of the control unit 13.
The performance of such steps is aimed to remove the cause or the causes of the malfunctioning of the circulation pump 11.
In a version of this control method, the restoring cycle further comprises a circulation pump checking step for controlling if the correct functioning of the circulation pump 11 has been restored, which the circulation pump checking step follows at least one of the rpm increasing step, the valve resetting step and the additional water drawing step.
In particular in a further version of the method, in the restoring cycle, the rpm increasing step, the valve resetting step and the additional water drawing step are all performed before the circulation pump checking step. More clearly, when a malfunctioning of the circulation pump 11 is detected, the control unit 13 commands the execution of all the three steps aimed to remove the cause of the malfunctioning before verifying if the circulation pump 11 returned to its correct functioning.
In an alternative version of the method, in the restoring cycle, the rpm increasing step, the valve resetting step and the additional water drawing step are performed in a sequence and after each of them, the circulation pump checking step is performed. More clearly, when a malfunctioning of the circulation pump 11 is detected, the control unit 13 commands the execution of the three steps aimed to remove the cause of the malfunctioning one by one in a sequence and after the execution of each of them the circulation pump checking step is performed, so that if any of such three steps succeeds in removing the cause of the malfunctioning of the circulation pump 11, the washing operation can be continued without needing to perform further steps of the restoring cycle.
In a further version of the control method according to the invention, the restoring cycle is repeated until the correct functioning of the circulation pump 11 has been restored or until a maximum number of repetitions n, which is set by the producer, has been reached. Therefore, the rpm increasing step, the valve resetting step, the additional water drawing step and the circulation pump checking step are repeated until the outcome of the circulation pump checking step is positive, i.e. until the correct functioning of the circulation pump 11 is restored, or, if the restoration of the correct functioning of the circulation pump 11 cannot be reached, such steps are repeated for a maximum number of repetition n, according to the settings of the producer.
According to a preferred version of the control method for a dishwasher 1 comprising a timer 16 as above specified, the method further comprises the steps of deactivating the circulation pump 11, activating the timer 16, maintaining the circulation pump 11 deactivated until the time period measured by the timer 16 has reached a limit value T* and repeating the restoring cycle until the correct functioning of the circulation pump 11 has been restored or until the maximum number of repetitions n has been reached.
These further steps are performed after the circulation pump checking step of the restoring cycle, once the maximum number of repetitions n of the restoring cycle has been reached and if the correct functioning of the circulation pump 11 has not been restored. The deactivation of the circulation pump 11 for an interval of time T* which is set by the producer, such as for instance 30 seconds, allows the circulation pump 11, and in particular its motor, to cool down, before restarting the repetitions of the restoring cycle.
The steps of deactivating the circulation pump 11, activating the timer 16, maintaining the circulation pump 11 deactivated until the time period measured by the timer 16 has reached a limit value T* are in particular commanded by the control unit 13 which is programmed to this aim.
According to a version of the control method according to the invention, the maximum number of repetitions n of the restoring cycle and the steps of deactivating the circulation pump 11, activating the timer 16, maintaining the circulation pump 11 deactivated until the time period measured by the timer 16 has reached a limit value T* and repeating the restoring cycle until the correct functioning of the circulation pump 11 has been restored or until the maximum number of repetitions n has been reached, are repeated until a maximum number of reiterations X* has been reached.
The maximum number of reiterations X* allows to stop the performance of the control method after a certain number of trials to restore the correct functioning of the circulation pump 11 have been executed without succeeding.
In a further version, the control method comprises a further step of generating an alarm signal, such as for instance a visual or an acoustic signal or both, to inform the user of the functioning problem of the circulation pump 11, which step is performed if the correct functioning of the circulation pump 11 has not been restored after the maximum number of reiterations X* has been reached.
Therefore, in case the reiteration for a number X* of times of a number n of repetition of the restoring cycle and of the cooling down steps for the circulation pump 11 has been performed without succeeding in restoring the correct functioning of the circulation pump 11, the control unit 13 is programmed for commanding the generation of an alarm signal so that the user is informed of the malfunctioning of the circulation pump 11 and can act consequently.
The dishwasher 1 and the control method according to the invention allows therefore to perform various attempts to automatically remove the conditions that determine the malfunctioning of the circulation pump 11 and in particular the dry running conditions of the latter, without requiring the direct intervention of the user. The steps of the restoring cycle of the control method, in fact, are generally sufficient to allow the optimal amount of washing liquid envisaged for the correct functioning of the circulation pump 11 to be restored and hence to allow an efficient washing performance of the dishwasher.

Claims

A dishwasher (1) comprising:
- a wash tub (2) in which the dishes to be washed are placed;

- a hydraulic circuit (3) for circulating washing liquid through the wash tub (2), connectable to an external source of water and having at least a first rotatable spray arm (4) and a second rotatable spray arm (5) arranged in the wash tub (2) to spray the dishes with the washing liquid, a sump (8) which is arranged in the lower section of the wash tub (2) to collect the washing liquid that has been sprayed on the dishes during washing operation, a filter (9) preventing the dirt from getting into the circulation during washing, and a duct (10) for conveying the filtered washing liquid from the sump (8) to the first spray arm (4) and the second spray arm (5);

- a circulation pump (11) arranged on the hydraulic circuit (3) downward of the sump (8) to draw the washing liquid from the sump (8) toward the first and second spray arms (4, 5) through the duct (10);

- a valve (12) arranged on the hydraulic circuit (3) downward of the circulation pump (11) for allowing to selectively deliver the washing liquid to the first spray arm (4) or to the second spray arm (5);

- a control unit (13) connected to the hydraulic circuit (3), to the circulation pump (11) and to the valve (12), for controlling their functioning during washing operation; characterized in that the control unit (13) is programmed to command the performance of the following operational steps upon the detection of a functioning problem of the circulation pump (11) deriving from dry run conditions, which occur when the amount of washing liquid drawn by the circulation pump (11) is less than the amount envisaged for the standard functioning conditions of the pump (11):
- increasing the rpm of the circulation pump (11);

- resetting the position of the valve (12) by commanding the valve (12) to be reenergized in order to reach a selected position; and

- drawing a further amount of water into the hydraulic circuit (3) from the external source of water.
A dishwasher (1) as in Claim 1, characterized in that it further comprises a timer (16) aimed to measure a time interval during which the circulation pump (11) is deactivated to allow it to cool down.
A control method for a dishwasher (1) according to Claim 1 or 2 comprising the steps of:
- determining that the circulation pump (11) is encountering a functioning problem deriving from dry run conditions, which occur when the amount of washing liquid drawn by the circulation pump (11) is less than the amount envisaged for the standard functioning conditions of the pump (11);

- generating an error signal associated with the functioning problem of the circulation pump (11) for the control unit (13); and

- performing by command of the control unit (13) a restoring cycle comprising:
- an rpm increasing step for increasing the rpm of the circulation pump (11);

- a valve resetting step for resetting the position of the valve (12) by commanding the valve (12) to be reenergized in order to reach a selected position; and

- an additional water drawing step for drawing a further amount of water into the hydraulic circuit (3) from the external source of water.
A control method for a dishwasher (1) as in Claim 3, wherein the restoring cycle further comprises a circulation pump checking step for controlling if the correct functioning of the circulation pump (11) has been restored, which step follows at least one of the rpm increasing step, the valve resetting step and the additional water drawing step.
A control method for a dishwasher (1) as in Claim 4, wherein, in the restoring cycle, the rpm increasing step, the valve resetting step and the additional water drawing step are all performed before the circulation pump checking step.
A control method for a dishwasher (1) as in Claim 4, wherein, in the restoring cycle, the rpm increasing step, the valve resetting step and the additional water drawing step are performed in a sequence and after each of them, the circulation pump checking step is performed.
A control method for a dishwasher (1) as in any of the claims 3 to 6, wherein the restoring cycle is repeated until the correct functioning of the circulation pump (11) has been restored or until a maximum number of repetitions (n) has been reached.
A control method as in claim 7 for a dishwasher (1) according to Claim 2, further comprising the steps of:
- deactivating the circulation pump (11);

- activating the timer (16);

- maintaining the circulation pump (11) deactivated until the time period measured by the timer (16) has reached a limit value (T*);

- repeating the restoring cycle until the correct functioning of the circulation pump (11) has been restored or until the maximum number of repetitions (n) has been reached;

- which steps are performed after the circulation pump checking step of the restoring cycle, after the maximum number of repetitions (n) of the restoring cycle has been reached if the correct functioning of the circulation pump (11) has not been restored.
A control method as in claim 8, wherein the maximum number of repetitions (n) of the restoring cycle and the steps of deactivating the circulation pump (11), activating the timer (16), maintaining the circulation pump (11) deactivated until the time period measured by the timer (16) has reached a limit value (T*) and repeating the restoring cycle until the correct functioning of the circulation pump (11) has been restored or until the maximum number of repetitions (n) has been reached, are repeated until a maximum number of reiterations (X*) has been reached.
A control method as in claim 9, further comprising a step of generating an alarm signal to inform the user of the functioning problem of the circulation pump (11), which step is performed if the correct functioning of the circulation pump (11) has not been restored after the maximum number of reiterations (X*) has been reached.