KR20120116326A - Dishwasher and method of controlling the same - Google Patents

Abstract

PURPOSE: A dish washer and a control method thereof are provided to improve sanitation by sterilizing the dish washer according to input for selecting a sterilizing course when restarting the dish washer after left for a long time. CONSTITUTION: A dish washer comprises a control panel with an input part for selecting a sterilizing course, a tub(12) accommodating tableware, a water supply unit(110) supplying washing water, a sump(100) receiving the washing water supplied from the water supply unit, a heater heating the washing water in the sump, and a steam jet nozzle(27) jetting steam, created according to the operation of the heater, into the tub.

Description

Dishwasher and its control method {Dishwasher and method of controlling the same}

The present invention relates to a dishwasher and a control method thereof.

In general, the dishwasher refers to a device that sprays washing water into a processing chamber such as a tub in which dishes are stored, and removes dirt from the dishes (in the case of a dishwasher having a drying function, it is dried).

Hygienic management is important above all, such as dishwasher, if left unused for a long time, hygiene problems such as bacteria grow by the remaining moisture or food residues inside, such as odor occurs .

In particular, when the user operates the dishwasher after leaving the house for a long time due to vacation or business trip, the user operates the dishwasher once for the purpose of cleaning the inside of the dishwasher, and then inserts the dishes and restarts the dishwasher. It was. In this case, the user selects a course (for example, a normal course) from among various courses provided in the control panel, which is generally used for washing dishes, and performs a drying process of drying the dishes through high temperature heating. This process takes a long time to complete the operation, and the drying operation performed during the course of the course is performed for a long time enough to dry the dishes. In addition, power consumption is also a burden.

The present invention provides a dishwasher having a sterilization course optimized for the function of sterilizing the device itself to solve the above problems.

In addition, the present invention provides a dishwasher having a function capable of quickly sterilizing the device itself before washing the dish in earnest when operating after standing for a long time.

In addition, the present invention provides a dishwasher that saves time and power required for device sterilization.

The dishwasher of the present invention includes a control panel having an input unit for receiving a sterilization course selection; Tub for storing tableware; A water supply unit for supplying washing water; A sump containing the washing water supplied from the water supply unit; A heater provided for heating the washing water in the sump; And a steam injection nozzle for injecting steam generated according to the operation of the heater into the tub, wherein the sump is equipped with a filter for filtering foreign substances included in the wash water on a movement path of the wash water flowing into the sump. The filter mounting portion is formed, the interior of the sump containing the wash water and the tub is communicated by the filter mounting portion, the sterilization course performed by the selective input of the input unit is the washing water is supplied to the sump, by the heater operation And a steam supply stroke that generates steam by heating the washing water in the sump.

When the dishwasher of the present invention is restarted in a state of being left unused for a long time, hygiene is improved by sterilizing the device itself according to the selection input of the sterilization course.

In addition, the dishwasher of the present invention has an effect of improving the sterilization effect on the filter mounting portion with high contamination.

In addition, the dishwasher of the present invention by providing a separate course for sterilizing the device, it is effective to reduce the time and power required to sterilize the device compared to the conventional method of performing a conventional cleaning course for sterilizing the device have.

1 illustrates a dishwasher according to an embodiment of the present invention.
2 is a block diagram showing a control relationship between major components of the dishwasher according to the embodiment of the present invention.
3 is a perspective view illustrating the inside of the tub of FIG. 1.
4 is an exploded perspective view of the sump shown in FIG. 3.
FIG. 5 is a cross-sectional view illustrating a partition formed in the sump of FIG. 3.
6 illustrates a control panel of the dishwasher according to one embodiment of the present invention.
7 is a graph showing the configuration of the sterilization course of the dishwasher according to an embodiment of the present invention and the temperature change of the inner side of the tub according to the progress of the sterilization course.
8 is a table illustrating various types of courses provided through the dishwasher.
9 is a table showing heat killing conditions according to types of pathogens and microorganisms.

1 illustrates a dishwasher according to an embodiment of the present invention. 2 is a block diagram showing a control relationship between major components of the dishwasher according to the embodiment of the present invention. 3 is a perspective view illustrating the inside of the tub of FIG. 1. 4 is an exploded perspective view of the sump shown in FIG. 3. 5 is a cross-sectional view illustrating a partition formed in the sump 100 of FIG. 3.

1 to 3, the dishwasher 1 according to an embodiment of the present invention includes a cabinet 11 forming an exterior, dishes are accommodated, and washing water or steam is applied to process the dishes. The tub 12 which provides the process chamber 12a, and the door 20 which opens and closes the process chamber 12a are included.

Inside the tub 11 are racks 16 and 17 for storing dishes, washing water spray nozzles 13, 14 and 15 for spraying washing water toward the dishes stored in the rack, and steam into the processing chamber 12a. It is provided with a steam injection nozzle 27 for spraying.

The rack may be disposed at the lower and upper portions of the processing chamber 12a, respectively, and the first washing water injection nozzle 13 may spray the washing water from the lower side to the upper side toward the lower rack 16 provided at the lower portion of the processing chamber; A second washing water spray nozzle 14 for spraying the washing water from the lower side toward the upper rack 17 provided in the upper portion of the processing chamber, and a third washing water spray nozzle for spraying the washing water from the upper side to the lower side toward the upper rack. 15 may be provided.

The steam injection nozzle 27 is connected to the sump 100 through the steam supply passage 26, and the steam generated by being heated by the heater 22, which will be described later, in the washing water contained in the collecting unit 110, is the steam supply passage. It is supplied to the steam injection nozzle 27 through.

The first washing water spray nozzle 13, the second washing water spray nozzle 14, and the third washing water spray nozzle 15 are respectively a first spray nozzle connecting passage 18, a second spray nozzle connecting passage 19, and a third The washing water is supplied from the sump 100 through the injection nozzle connection passage 21.

The sump 100 includes a water collecting unit 110 containing the washing water. The washing water stored in the collecting unit 110 is pumped to the washing water injection nozzles 13, 14, and 15 by the pump 150. In particular, the pump 150 is operated and the washing water is injected into the tub 12, and the washing water collected in the tub bottom 12b flows back into the sump 100, thereby circulating the washing water between the sump and the tub. Therefore, the sump 100 is not only communicated with the inside of the tub through the steam injection nozzle 26, but also communicated with the tub through a path through which the wash water flows from the tub.

More specifically, the dishwasher 1 includes a filter 140 for filtering foreign matter such as food waste floating in the wash water, and the filter includes a flow path of the wash water flowing from the tub 12 into the sump 100. Is disposed on. To this end, the sump 100 is formed with a filter mounting portion 123 to which the filter 140 is mounted, and thus, the sump is communicated with the tub 12 through the filter mounting portion as well as the steam injection nozzle 27. . The flow path 170 is a flow path communicating the filter mounting part 123 and the water collecting part 110.

A path through which steam generated when the washing water in the sump 100 is heated by the heater 22 is supplied into the tub 12 is provided through a steam supply passage 26 and a steam injection nozzle 27. And a second flow path supplied through the filter mounting part 123. In particular, since the filter 140 is mounted on the second flow path, the filter is sterilized by steam.

The filter mounting part 123 may be recessed into the sump 100 so that the washing water flowing from the tub 12 may be smoothly gathered. Such a structure may also be easily detachable from the filter 140. .

The water supply unit 33 is connected to an external water source such as a faucet to supply washing water into the sump 100, a water supply passage 23 through which the washing water supplied from the external water source flows, and a water supply valve for intermitting the water supply passage. It may include (not shown), in the present embodiment, the water supply passage is directly connected to the sump, and passed through the filter 140 to the water collecting unit 110, but is not necessarily limited thereto. For example, water may be directly supplied into the tub 12 through the water supply passage 23, in which case, the washing water flows from the tub to the reservoir after passing through the filter mounting portion 123 and the filter. .

The drain 28 is for draining the wash water in the sump 100 to the outside of the dishwasher, and may include a drain pump 25. In the present embodiment, the filter mounting part 123 is connected to the drain passage 24, and when the drain pump 25 is operated, the washing water passing through the filter 140 is drained out of the dishwasher 1 through the drain passage. .

The pump 150 pumps the washing water collected in the water collecting unit 110 to at least one of the plurality of washing water injection nozzles 13, 14, and 15, and the washing motor 152 and the impeller 151 rotated by the washing motor. It may include.

On the other hand, although the arrangement relationship between the major components of the dishwasher 1 is schematically shown in FIG. 1, the arrangement relationship of each component pipe is not necessarily limited thereto. For example, when FIG. 1 is viewed in terms of arrangement between components, it may be understood that the washing motor 152 is disposed within the sump 100 (although such a structure is also possible), but this is due to the difficulty of illustration. In addition, other implementations can be said as much as possible.

In this embodiment, the cleaning motor 152 is disposed outside of the sump 100, in particular between the collecting part 110 and the collecting plate 121 (see FIG. 4), to increase the space utilization in the cabinet 11. It is possible to increase the capacity of the washing chamber (12a) accordingly.

The water level sensor 31 is for detecting the quantity of wash water supplied for dish washing, and is installed in the sump to detect the water level in the sump 100 or in the tub to sense the water level in the tub 12. Various implementations such as being installed are possible.

Alternatively, it is possible to detect the flow rate of the washing water installed on the flow path of the washing water supplied to the sump 100, and to estimate the amount of washing water required for washing or rinsing the dishes based on the detected flow rate.

The temperature sensor 32 is for estimating the temperature of the inner surface of the tub 12, but may be provided to directly measure the temperature of the inner surface of the tub 12, but is not necessarily limited thereto. 12) Even when provided to detect elements other than the inner side, it is sufficient that the temperature of the inner side of the tub 12 can be estimated from the sensed temperature value. However, the sterilization course provided by the dishwasher 1 according to the embodiment of the present invention reaches a temperature sufficient for killing pathogens and microorganisms by the temperature of the inner side of the tub by steam supplied into the tub 12. It is obvious that the temperature of steam is generally 100 degrees Celsius or more. When measuring the temperature of the air inside the tub through the temperature sensor, it will be difficult to estimate the temperature of the inner surface of the tub based on this. .

However, the temperature sensor 32 is not necessarily a configuration necessary for achieving the object of the present invention. Even when there is no temperature sensor 32 or when the temperature of the inner surface of the tub 12 cannot be estimated through the temperature sensor, the temperature of the inner surface of the tub increases as the time for supplying steam into the tub increases. Obviously, the temperature change of the inner surface of the tub according to the steam supply time can be known by experiment. Therefore, according to the correlation between the steam supply time into the tub 12 obtained by the experiment and the temperature change of the inner surface of the tub, during the sterilization course operation so that the temperature of the inner surface of the tub to meet the conditions for killing pathogens and microorganisms The time for which steam is supplied into the tub may be set.

The input unit 35 receives various control commands from the user for controlling the operation of the dishwasher 1 and may be provided through the control panel 200 (see FIG. 8). The input unit 35 may be implemented by various means such as a button, a dial, or a touch pad / screen.

In particular, the user can select and input the sterilization course through the input unit 35, if the sterilization course is selected through the input unit, the water supply unit 33, the heater 22, the pump ( 150), the drain 28 is operated, sterilization course is performed according to a predetermined algorithm.

The control unit 29 is for controlling each part constituting the dishwasher 1, and controls the overall operation of the dishwasher 1, and the term control or setting used in connection with the operation of each part is generally referred to below. Means control or setting by the control unit 29.

Referring to FIG. 4, the sump 100 may include a sump housing 120 and a sump cover 160. A sump housing 120 and a filter mounting part 123 may be formed in the sump housing 120, and the sump cover 160 is provided at an upper side of the sump housing 120, and the tub 12 may be connected to the sump housing. A plurality of micropores 164 may be formed to allow the incoming washing water to pass therethrough.

In addition, the sump cover 160 includes a first connector 161 connected to the first injection nozzle connection channel 18, a second connector 162 and a third injection nozzle connected to the second injection nozzle connection channel 19. A third connector 163 is formed to be connected to the connection passage 21.

The flow path switching unit 130 selectively supplies the washing water pumped by the pump 150 to at least one of the first washing water spray nozzle 13, the second washing water spray nozzle 14, and the third washing water spray nozzle 15. will be.

More specifically, the sump housing 120 is formed with a washing water supply passage 180 for guiding the washing water pumped by the pump 150, and the flow path switching unit 130 is the washing water injection nozzle 13 through the washing water supply passage. , 14, 15) to control the flowing water. As described above, the washing water spray nozzles 13, 14, and 15 may be provided in plural, and in this case, the washing water may be selectively selected by at least one of the plurality of washing water spray nozzles by the operation control of the flow path switching unit 130. Can be supplied.

The flow path switching unit 130 includes a flow path switching motor 132 and a rotating plate 131 rotated by the flow path switching motor. At least one hole is formed in the rotating plate 131.

When at least one hole formed in the rotating plate is located at a position corresponding to at least one of the plurality of connectors 161, 162, and 163 according to the rotation control of the flow path switching motor 132, it is supplied through the washing water supply passage 180. The washing water is sprayed through at least one of the plurality of washing water spray nozzles (13, 14, 15). That is, the washing water spraying of the plurality of washing water spraying nozzles 13, 14, and 15 is the washing water spraying nozzle communicating with the washing water supply passage 180 through the hole formed in the rotating plate 131.

On the other hand, the rotation of the rotating plate 131 is controlled stepwise by the flow path switching motor 132, the flow path switching motor advances by a certain angle each time the excitation state is changed by the input pulse signal, if the excitation state does not change It may be a step motor (step motor, stepper motor or stepping motor) to maintain a fixed position.

1 and 5, the sump housing 160 is formed to surround the impeller 151, and a flow guide 116 is formed to guide the flow of the washing water discharged through the wings of the impeller. The flow guide is connected to the wash water supply passage 180. The connector 180a formed in the flow guide 116 of FIG. 5 is for connection with the washing water supply passage 180.

The steam generated in the sump 100 by the operation of the heater 22 is injected into the tub 12 through the steam injection nozzle 27, and the other through the filter mounting part 123, as described above. Supplied into the tub. At this time, it is preferable that the internal space of the sump 100 is partitioned so that steam generated in the sump 100 can branch and flow into the steam injection nozzle 27 and the filter mounting part 123. To this end, a partition wall 115 is formed on the rear surface of the flow guide portion 116 surrounding the impeller 151, and the partition wall protrudes toward the water collecting portion 110 from the rear surface of the flow guide portion. In addition, a part of the partition wall 115 is formed around the inlet 116h of the pump 150, so that the inlet 116h of the pump 150 is positioned at one side of the inner space of the sump 100 partitioned by the partition wall. The other side of the sump internal space partitioned by the partition wall communicates with the steam supply passage 26. The connector 26a of FIG. 5 is connected to the steam supply passage 26.

In more detail, the partition wall 115 may be provided at an upper portion of the inner space of the reservoir 110. The partition wall 115 may not partition the inner space of the reservoir 110 but may partition the partitioned spaces so as to communicate with each other. As shown in FIG. 5, the partition wall 115 may extend by a predetermined length toward the lower side from the bow of the flow path guide part 116 forming the upper surface of the reservoir 110. Therefore, the first space 5 and the second space 7 partitioned on both sides by the partition wall 115 communicate with each other through a gap between the bottom of the partition wall 115 and the bottom surface of the reservoir 110. The wash water passing through the assembly 140 fills both the first space and the second space.

On the other hand, the heater 22 is sufficient to heat the wash water contained in the reservoir 110, may be provided so as to be exposed to the wash water contained in the reservoir, it is also embedded in the sump housing 120 (see Fig. 4) It is possible.

6 illustrates a control panel of the dishwasher according to one embodiment of the present invention. 7 is a graph showing the configuration of the sterilization course of the dishwasher according to an embodiment of the present invention and the temperature change of the inner side of the tub according to the progress of the sterilization course. 8 is a table illustrating various types of courses provided through the dishwasher. 9 is a table showing heat killing conditions according to types of pathogens and microorganisms.

Referring to FIG. 6, the dishwasher 1 according to the embodiment of the present invention includes a control panel 200 that provides an input unit 35.

In this embodiment, the control panel 200 is provided on the upper portion of the door 20 as an example, but is not limited thereto. For reference, the handle 20a of FIG. 6 is for the door 20 to be opened and closed.

The control panel 200 includes a button or operation keys 230 and 240 constituting the input unit 35, an indicator 210 for displaying a current stroke, and a display unit for displaying overall operation of the dishwasher 1. 220 is provided. The indicator 210 includes a plurality of light emitters flashing according to the current stroke, and blinks in response to the progress of the WASH, RINSE, and DRY strokes, and is completed when all the strokes are completed. (CLEAN) lights up for a predetermined time.

The user may set a rinse condition (RINSE OPTIONS) through the course setting unit 230, the rinse condition to add a sanitary rinsing (SANITARY), rinsing stroke for heating and spraying the washing water until a predetermined temperature is reached. EXTRA RINSE or the like may be provided.

Detailed administrations constituting the POWER SCRUB, NORMAL, QUICK, RINSE ONLY courses are shown in FIG. 8.

Referring to FIG. 8, the washing water heated into the tub 12 during the washing stroke (WASH) or the rinsing stroke (RINSE) is removed by removing the rinsing-only course among the strong washing course, the general course, the quick course and the rinsing course. Then, a drying stroke DRY is performed. Therefore, while these courses are performed, the temperature inside the tub 12 is raised, whereby a predetermined sterilizing effect can be expected. For this reason, in the conventional case where a sterilization course was not separately provided in the dishwasher, when the user operates the dishwasher that has been left unused for a long time, the power washing course (POWER SCRUB) must be used to sterilize the dishwasher itself before washing the dishes. ), The general course (NORMAL), or quick course (QUICK) was often driven. However, each of the above courses takes at least 78 minutes to complete the course, at least 10 L of water, and the temperature of the washing water sprayed from the washing stroke or the rinsing stroke reaches only 68 degrees Celsius, which kills pathogens and microorganisms. In spite of insufficient power, there were problems such as long operation time, excessive power and water consumption.

Therefore, the dishwasher 1 according to the embodiment of the present invention provides a sterilization course adapted to sterilize the device itself, and the sterilization course can be selected through the input unit 35 of the control panel 200. The sterilization course selection unit 240 of FIG. 6 is an input unit for receiving input of a sterilization course (STERILSZATION).

When the sterilization course is selected and input through the sterilization course selecting unit 240, the control unit 29 controls the sterilization course to operate according to a preset algorithm. Hereinafter, detailed administrations constituting the sterilization course will be described with reference to FIG. 7. Explain.

7, sterilization course provided through the dishwasher 1 according to an embodiment of the present invention is a steam supply stroke (Steam, 310), washing stroke (Washing, 320), drying stroke (Drying, 330) It includes.

In the steam supply stroke 310, steam is supplied into the tub 12 through the steam injection nozzle 27 and the filter mounting part 123. First, the washing water is supplied into the sump 100 through the control of the water supply 33, and the washing water in the sump is heated by the heater 22 to generate steam. At this time, some of the generated steam is injected into the tub 12 through the steam injection nozzle 27, the other part is supplied into the tub through the filter mounting portion 123 formed in the sump (100).

Since steam is supplied into the tub 12 during the steam supply stroke 310, the temperature of the inner side of the tub 12 gradually increases, and the temperature of the inner side of the tub is sufficient to heat and kill pathogens and microorganisms. The temperature should be maintained for a certain time. Temp0 in FIG. 7 is close to room temperature (20 degrees Celsius) at the initial temperature in tub 12.

9 shows heat killing conditions according to the types of pathogens and microorganisms, and most pathogens except anthrax have a characteristic of being extinct within a predetermined time at 60 degrees Celsius or more. However, tuberculosis bacteria, Pseudomonas aeruginosa, and enterococci can survive at least 10 minutes at a temperature of about 60 degrees Celsius, and in order to reduce the time required for death, it is necessary to raise the heating temperature to 60 degrees Celsius or more. In order to kill E. coli O157, the heating temperature must be maintained for at least 1 minute above 75 degrees Celsius. Therefore, the temperature of the inner surface of the tub 12 in the steam supply stroke 310 is preferably maintained for more than 1 minute at 75 degrees Celsius or more, in this case can kill most pathogens propagated in the tub 12.

The operation of the heater 22 in the steam supply stroke 310 is controlled based on the detected value of the temperature sensor 32, or obtains the temperature change of the inner surface of the tub 12 according to the operation time of the heater by an experiment, It may be controlled based on this as described above.

After the steam supply stroke 310, the pump 150 is operated and a washing stroke 320 for spraying the washing water into the tub 12 through the at least one washing water spray nozzle 13, 14, 15 may be further implemented. have.

In addition, after the washing stroke 320, the drain pump 25 is operated to drain the washing water in the sump 100, the drying stroke 330 to dry the inside of the tub 12 by operating the heater 22 is more Can be implemented.

The sterilization course described above is not intended to wash dishes, but to sterilize the dishwasher itself, and the steam stroke, washing stroke or drying stroke constituting the sterilization course are courses for washing dishes, for example. For example, compared to the administrations performed during the intensive cleaning course and the general course, it is sufficient to simply configure the operation algorithm, and the time required for each administration is also relatively short.

In particular, in order to sterilize pathogens, the temperature of the inner surface of the tub 12 must be raised to a predetermined temperature so as to satisfy the killing condition of the pathogen. As described above, the temperature of the inner surface of the tub is equal to or greater than 75 degrees for 1 minute. It can be seen that if the pathogen persists, most pathogens are killed. According to the experiments, the time taken for killing most pathogens as described above was sufficient after 20-30 minutes after the steam supply administration. In particular, since the washing stroke or drying stroke performed after the steam feeding stroke is shorter than the steam feeding stroke, all the strokes constituting the sterilization course can be completed in a relatively short time within 60 minutes.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

Claims (13)

A control panel having an input for receiving a sterilization course selection;
Tub for storing tableware;
A water supply unit for supplying washing water;
A sump containing the washing water supplied from the water supply unit;
A heater provided for heating the washing water in the sump; And
Steam injection nozzle for injecting steam generated by the operation of the heater into the tub,
The sump,
On the movement path of the washing water flowing into the sump, a filter mounting portion for mounting a filter for filtering foreign matter contained in the washing water is formed, the filter mounting portion is in communication with the inside of the sump containing the wash water,
Sterilization course performed by the selected input of the input unit,
Washing water is supplied to the sump, the dishwasher comprising a steam supply stroke for generating steam by heating the washing water in the sump by the heater operation. The method of claim 1,
Some of the steam generated in the sump is injected into the tub through the steam injection nozzle, the other part is supplied into the tub through the filter mounting portion. The method of claim 1,
When the steam is supplied into the tub by the heater operation, the inner surface temperature of the tub is maintained for more than 75 degrees for a predetermined time. The method of claim 3, wherein
The predetermined time is set to more than 1 minute dishwasher. The method of claim 3, wherein
Further comprising a temperature sensor for estimating the temperature of the inner surface of the tub,
Operation of the heater is controlled according to the temperature measured by the temperature sensor. The method of claim 1,
A washing water spray nozzle provided in the tub; And
Further comprising a pump for pumping the washing water in the sump to the washing water injection nozzle,
The sterilization course,
After the steam supply stroke, the washing machine further comprises a washing stroke for operating the pump to spray the washing water through the washing water spray nozzle. The method according to claim 6,
Further comprising a drain for draining the washing water in the sump,
Said meat course,
And after the washing stroke, operating the drainage part to drain the washing water in the sump and operating the heater. Selecting and sterilizing the course through the input unit; And
The sterilization course is operated,
The sterilization course is operated,
Controlling the dishwasher by heating the washing water contained in the sump to generate steam and supplying the generated steam to the tub through a steam injection nozzle and a filter mounting portion formed in the sump and communicating with the tub. Way. The method of claim 8,
The steam supplying step,
Control method of the dishwasher, characterized in that for controlling the operation of the heater so that the inner temperature of the tub lasts for more than 75 degrees for a predetermined time. The method of claim 9,
The predetermined time is a control method of the dishwasher, characterized in that more than 1 minute. The method of claim 9,
Operation of the heater in the steam supply step,
The control method of the dishwasher, characterized in that controlled based on the measured temperature of the temperature sensor reflecting the temperature change of the inner surface of the tub. The method of claim 8,
The sterilization course is operated,
After the steam supply step, the washing method of the dishwasher further comprises a washing step of spraying the washing water in the sump into the tub through the washing water injection nozzle. 13. The method of claim 12,
The sterilization course is operated,
And a drying step of draining all of the washing water in the sump and operating a heater provided to heat the washing water in the sump after the washing stroke.

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