DISHWASHER

TECHNICAL FIELD

The invention relates to a dishwasher comprising at least one rotating wash arm arranged to spray process water onto goods to be cleaned in a compartment of the dishwasher where operational states are determined by detecting splashes of process water, and a method at a dishwasher for determining operational states.

BACKGROUND

In dishwashers, it is desirable to detect various operational states causing failures that can lead to dishwasher damage. Further, it may be desirable to detect operational states of the dishwasher in order to take appropriate measures for controlling the operation of the dishwasher depending on the detected operational state. As an example, EP 2 599 424 discloses a dishwasher being equipped with a sensor, such as an accelerometer, for detecting abnormal vibrations which could signify a malfunction or warn of an imminent breakage. For instance, should rotating wash arms positioned in a washing compartment of the dishwasher come into contact with dishes, vibrations would be produced which could be transmitted through structures of the dishwasher and which therefore would be detectable by the sensor. In this regard, the abnormal vibrations could be communicated to a user and, in the most serious cases, could even stop the operation of the dishwasher.

A problem in the art is how to provide an efficient mechanism for detecting operational states of a dishwasher. SUMMARY

An object of the present invention is to solve or at least mitigate this problem in the art and to provide an improved dishwasher arranged with equipment for detecting an operational state of the dishwasher. This object is attained in a first aspect of the present invention by a dishwasher comprising at least one rotating wash arm arranged to spray process water onto goods to be cleaned in a compartment of the dishwasher. The dishwasher further comprises at least one sensor arranged to detect shocks caused by splashes of process water in the compartment, and arranged to communicate a signal in response thereto indicative of a detected property of the shocks. The dishwasher further comprises a controller arranged to receive the signal and to determine an operational state of the dishwasher according to the detected property.

This object is attained in a second aspect of the present invention by a method of determining an operational state of a dishwasher comprising at least one rotating wash arm arranged to spray process water onto goods to be cleaned in a compartment of the dishwasher. The method comprises detecting a property of shocks caused by splashes of process water in the compartment, and determining an operational state of the dishwasher according to the detected property.

Advantageously, the present invention enables detection of splashes of process water within the compartment of the dishwasher. The splashes onto inner walls of the compartment will result in shocks affecting the sensor comprised in the dishwasher. Thus, shocks caused by the splashes of process water in the compartment are detected, and by analysing a property of the shocks caused by the splashing water, different operational states of the dishwasher can be detected - and possibly attended to - as will be described in more detail with reference to embodiments of the invention.

In a first embodiment of the present invention, an operational state related to wash arm blockage is advantageously determined. By detecting irregularly occurring splashes of process water, i.e. the property of the shocks caused by the splashes being that the shocks occur irregularly on the sensor, it can be concluded that the one or more wash arms are at least partially blocked.

In an alternative to the first embodiment, the operational state related to wash arm blockage is advantageously determined by detecting that no splashes of process water occur, i.e. the property of the shocks caused by the splashes being that the no shocks at all occur on the sensor, implying that the one or more wash arms are completely blocked and hence do not splash any process water at all onto the inner walls of the compartment. In a second embodiment of the present invention, an operational state related to a low amount of goods to be cleaned being loaded in the

compartment is advantageously determined by detecting that the process water splashes onto the inner walls of the compartment with a strength that is greater than normal. Hence, the property of the shocks caused by the splashes is that the shocks have a relatively great strength, thereby making a great impact on the sensor. Thus, in case the detected property indicates that strength of the splashes of process water exceeds a predetermined threshold value, it can be concluded that the compartment is loaded with a small amount of goods to be cleaned. In contrast, in case the compartment is full of goods, the goods itself will acts as damping means for splashes. However, in case there are little (or even no) goods in the compartment, the process water will splash onto the inner walls of the compartment with greater strength.

In embodiments of the present invention, the detection that the compartment is loaded with a small amount of goods to be cleaned can advantageously be used for controlling a number of components of the dishwasher.

Firstly, the controller may advantageously control a water inlet in order decrease water supply to the dishwasher, thus saving water and contributing to increased sustainability. Secondly, the controller may advantageously control a circulation pump in order to decrease process water circulation speed of the dishwasher, thus providing more energy-efficient dishwasher control. Thirdly, the controller may control a drain pump in order to decrease process water drainage of the dishwasher, again saving water.

In yet a further embodiment of the present invention, the controller is advantageously arranged to communicate the operational state of the dishwasher to a user via a user interface, such that the user can take further action. This can be performed visually and/ or audibly via a user interface typically located at an upper section of the dishwasher door.

In still a further embodiment of the present invention, the controller is advantageously arranged to interrupt a current washing program in response to the determined operational state, in case the operational state is serious and may cause further damage to the dishwasher.

In yet another embodiment of the present invention, the controller advantageously determines that the operational state of the dishwasher is related to adequate rotation of the at least one wash arm, in case the detected property indicates regularly occurring splashes of process water. Thus, in case it is determined that the one or more wash arms rotate with an adequate rotational speed, it can be deducted that there is no wash arm blockage and that the dishwasher is operating correctly. In such a case, the controller may advantageously control a heater for heating the process water in response thereto.

It is noted that the invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following.

BRIEF DESCRIPTION OF THE DRA WINGS

The invention is now described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a dishwasher in which the present invention is implemented;

Figure 2 shows a top view of the dishwasher compartment of Figure 1; and

Figure 3 shows a flowchart of an embodiment of the method according to the present invention. DETAILED DESCRIPTION

The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

By the expression "process water" as used herein, is meant a liquid containing mainly water that is used in and circulates in a dishwasher. The process water is water that may contain detergent and/ or rinse aid in a varying amount. The process water may also contain soil, such as food debris or other types of solid particles, as well as dissolved liquids or compounds. Process water used in a main wash cycle is sometimes referred to as the wash liquid. Process water used in a rinse cycle is sometimes referred to as cold rinse or hot rinse depending on the temperature in the rinse cycle.

Figure 1 shows a dishwasher 10 in which the present invention is

implemented. It should be noted that dishwashers can take on many forms and include many different functionalities. The dishwasher 10 illustrated in Figure 1 is thus used to explain different embodiments of the present invention and should only be seen as an example of a dishwasher in which the present application can be applied. The dishwasher 10 comprises a washing compartment or tub 11 housing an upper basket 12, a middle basket 13 and a lower basket 14 for accommodating goods to be washed. Typically, cutlery is accommodated in the upper basket 12, while plates, drinking- glasses, trays, etc. are placed in the middle basket 13 and the lower basket 14.

Detergent in the form of liquid, powder or tablets is dosed in a detergent compartment located on the inside of a door (not shown) of the dishwasher 10 by a user, which detergent is controllably discharged into the washing compartment 11 in accordance with a selected washing programme. The operation of the dishwasher 10 is typically controlled by processing unit/ controller 40 executing appropriate software.

Fresh water is supplied to the washing compartment 11 via water inlet 15 and water supply valve 16. This fresh water is eventually collected in a so called sump 17, where the fresh water is mixed with the discharged detergent resulting in process water 18. At the bottom of the washing compartment is a filter 19 for filtering soil from the process water before the process water leaves the compartment via process water outlet 20 for subsequent re-entry into the washing compartment 11 through circulation pump 21. Thus, the process water 18 passes the filter 19 and is pumped through the circulation pump 21, which typically is driven by a brushless direct current (BLDC) motor 22, via a conduit 23 and respective process water valves 24, 25 and sprayed into the washing compartment 11 via nozzles (not shown) of a respective wash arm 26, 27, 28 associated with each basket 12, 13, 14. Thus, the process water 18 exits the washing compartment 11 via the filter 19 and is recirculated via the circulation pump 21 and sprayed onto the goods to be washed accommodated in the respective basket via nozzles of an upper wash arm 26, middle wash arm 27 and lower wash arm 28. The washing compartment 11 of the dishwasher 10 is drained on process water 18 with a drain pump 29 driven by a BLDC motor 30. It should be noted that it can be envisaged that the drain pump 29 and the circulation pump 21 may be driven by one and the same motor.

Further, the dishwasher of the present invention is arranged with at least one sensor, such as an accelerometer, for detecting shocks caused by splashes of process water 18 in the compartment 11, and to communicate a signal in response thereto indicative of a detected property of the shocks to the controller 40. In this particular exemplifying embodiment, three different sensors 31, 32, 33 are used, each one arranged in connection to the respective wash arm 26, 27, 28. Thus, when the upper wash arm 26 rotates periodically with an adequate rotational speed determined by the selected washing programme, process water will be discharged via the nozzles of the upper wash arm 26 and splash onto the upper sensor 31 with a given, adequate frequency (corresponding to the rotational speed of the upper wash arm 26 determined by the selected washing programme). As can be seen in Figure 1, the sensors are mounted in the chassis 34 and in mechanical contact with the inner wall of the washing compartment 11. In an embodiment, the sensors 31, 32, 33 are mounted in the door of the dishwasher while mechanically contacting the inner wall of the door. As soon as the process water 18 does not regularly splash onto the upper sensor 31 via the upper rotating wash arm 26, which splashes are detected at the upper sensor 26 in the form of shocks impacting on the inner wall of the compartment 11, the controller 40 deducts that wash arm blockage has occurred by receiving and analysing a signal from the upper sensor 31. Thus, a particular property of the shocks impacting on the upper sensor 31 is detected; in this case, the property is that the shocks occur irregularly (or not at all). Typically, the upper sensor 31 communicates a signal reflecting each shock impacting on the sensor and the controller 40 performs an analysis of the signal to determine the frequency with which the shocks impact on the sensor 31. From this analysis, the controller 40 determines the operational state of the dishwasher 10.

If the splashes are irregular, a partial wash arm blockage is determined, implying that the wash arm is not completely stuck but actually rotates, albeit with an irregular speed. On the other hand, if no splashes at all are detected, a complete wash arm blockage is determined, meaning that the wash arm is unable to rotate. The same reasoning can be made for the middle wash arm 27 and the associated middle sensor 32, and for the lower wash arm 28 and the associated lower sensor 33.

Figure 2 shows a top view of the dishwasher compartment 11 and the rotating upper wash arm 26. Each time the rotating wash arm passes the sensor 31, it will splash water onto the inner wall of the compartment with which the sensor is in mechanical contact, whereby the operational state of the dishwasher can be determined as has been discussed.

Again with reference to Figures 1 and 2, in an embodiment of the present invention, the controller 40 advantageously determines that the operational state of the dishwasher 10 is related to adequate rotation of one or more of the wash arms 31, 32, 33, in case the detected property indicates regularly occurring splashes of process water. Thus, in case it is determined that the one or more wash arms rotate with an adequate rotational speed, it can be deducted that there is no wash arm blockage and that the dishwasher is operating correctly. In such a case, the controller 40 may advantageously control a heater 35 for heating the process water 18 in response to the detected correct behaviour of the dishwasher 10.

In a further embodiment of the present invention, an operational state in the form of a low amount of goods to be cleaned in the compartment is detected. In this embodiment, if one or more of the upper, middle and lower sensors 31, 32, 33 detects that the process water 18 splashes onto the inner walls of the compartment 11 of the dishwasher 10 with a strength that is greater than normal, it is determined that the operational state of the dishwasher 10 relates to a low amount of goods to be cleaned in the compartment 11. Thus, the property of the shocks is that they make a greater impact than normal on the sensor(s) 31, 32, 33. This is determined by having the controller 40 compare the strength of the impacting shocks with a predetermined threshold value, and if the strength exceeds the threshold value, the shocks are considered strong enough to indicate that a low amount of goods has been loaded into the compartment 11. Advantageously, the detection of this operational can be used to control one or more components of the dishwasher 10. Firstly, if the amount of goods loaded in the compartment 11 is low, the controller 40 may advantageously control the supply of fresh water to the washing compartment 11 via water inlet 15 and water supply valve 16. A smaller amount of goods loaded in the compartment 11 requires a smaller amount of fresh water, thus saving water and contributing to increased sustainability.

Secondly, the controller 40 may advantageously control the circulation pump 21 in order to decrease circulation speed of the process water 18 , thus providing more energy- efficient dishwasher control. Thus, the process water 18 collected in the sump 17 exits the filter 19 at the bottom of the washing compartment 11 for filtering soil from the process water before the process water leaves the compartment via process water outlet 20 for subsequent reentry into the washing compartment 11 through the circulation pump 21 driven by the BLDC motor 22. The process water 18 re-enters the

compartment 11 via the conduit 23 and the respective process water valves 24, 25 and is sprayed into the washing compartment 11 via the nozzles of the respective wash arm 26, 27, 28 associated with each basket 12, 13 , 14. The controller hence controls the circulation pump 21 by adjusting the speed of the BLDC motor 22 to control the circulation of process water 18. A smaller amount of goods loaded in the compartment 11 requires a lower circulation speed, thus resulting in lower power consumption.

Thirdly, the controller 40 may control the drain pump 29 in order to decrease process water 18 drainage of the dishwasher, again saving water. The washing compartment 11 of the dishwasher 10 is drained on process water 18 with the drain pump 29 driven by a BLDC motor 30. A smaller amount of goods loaded in the compartment 11 generally results in less soil and dirt in the process water 18 , implying that the process water 18 can be used for a longer time period before draining via the circulation pump 29 is undertaken, again saving water. A further advantage with all these three embodiments relating to control of the water inlet 15, the circulation pump 21 and the drain pump 29 is that the dishwasher 10 will become more silent-running.

In a further embodiment, the controller 40 is advantageously arranged to communicate the operational state of the dishwasher 10 to a user via a user interface 36, such that the user can take further action. This can be performed visually and/ or audibly via the user interface 36 typically located at an upper section of the dishwasher door. In still a further embodiment of the present invention, the controller 40 is advantageously arranged to interrupt a current washing program in response to the determined operational state, in case the operational state is serious and may cause further damage to the dishwasher 10. The interruption may be

communicated via the user interface 36.

Figure 3 shows a flowchart of an embodiment of a method of determining an operational state of a dishwasher comprising at least one rotating wash arm arranged to spray process water onto goods to be cleaned in a compartment of the dishwasher. In a first step S101, a property of shocks caused by splashes of process water in the compartment is detected. Thereafter, in step S102 an operational state of the dishwasher is determined according to the detected property.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.