EP2156775B1

EP2156775B1 - Control method for a dishwasher

Info

Publication number: EP2156775B1
Application number: EP09010552.9A
Authority: EP
Inventors: Seong Ho Kim; Young Hwan Park; Yong Jin Choi
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2008-08-21
Filing date: 2009-08-17
Publication date: 2019-05-22
Anticipated expiration: 2029-08-17
Also published as: CN101653352B; US20100043832A1; EP2156775A2; KR20100023172A; CN101653352A; EP2156775A3

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a control method for a dishwasher. More particularly, the present invention relates to a control method of a dishwasher capable of securing enough washing efficiency without an operation of a sump heater provided in a sump to contain washing water or rinsing water and capable of reducing wasted power.

Discussion of the Related Art

Conventional dishwashers are generally automated washing machines, which spray washing water and detergent to soiled dishes, glassware, flatware, etc. (hereinafter dishes) placed in a tub to remove foreign particles, such as food scraps, left on the dishes, to automatically wash the dishes.
The dishwashers are operated generally based on a washing cycle for spraying washing water mixed with detergent into a tub containing the dishes to remove foreign particles from the dishes. Dishwashers also have rinsing cycles for spraying a washing water free of detergent into the tub to remove the remaining foreign matter and the detergent after the washing cycle has been performed. Finally, a drying cycle is usually performed after the washing and rinsing cycles to dry the dishes. Recently, a dishwasher that is capable of heating washing water in the washing cycle to further increase the washing effect has been developed.
Conventional dishwashers generally perform the washing, rinsing and drying cycles sequentially. As mentioned above, recently the washing water has been heated during in the washing or rinsing cycle. The reason why the washing or rinsing water is heated in the washing or rinsing cycles is to maximize the washing efficiency. As a result, to heat the washing water or rinsing water, a sump heater is provided in a sump where the washing/rinsing water collects.
Sump heaters, however, use an electric heater, which has several disadvantages. An electric heater may consume large amounts of power, beyond that which the system may actually need, thus lowering the system's power efficiency.
Dishwashers may be preferable to hand washing to reduce the amount of time and water that is used to wash a large amount of dishes. The large power consumption of a dishwasher caused by an electric heater, however, may make it less desirable for a user to operate a dishwasher.
WO 2008/047981 A1 describes a method of controlling a dishwasher. The method includes performing a preliminary washing for washing dishes using washing water not containing detergent, performing a main washing for washing the dishes using washing water containing detergent, and performing a rinsing for rinsing the dishes. A steam supplying step is performed during the step of main washing and the step of heating rinsing. However, in both of these steps, the steam supplying and the water supplying are repeated alternately, which increases energy consumption.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a control method of a dishwasher. The control method may perform a more efficient drying.
Additional advantages and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
The above identified problems are solved by the features of the independent claim. Preferably, a control method of a dishwasher comprising a washing compartment, a sump configured to contain water, a steam generator, and at least one spraying arm. The method may include performing a washing cycle comprising spraying water toward at least one rack provided in the washing compartment and supplying steam to the washing compartment, the spraying water and the supplying steam being repeated alternately until a temperature of the water reaches a preset first temperature; and drying including heating the washing compartment by supplying steam to the washing compartment, until a temperature of a dish contained in the washing compartment reaches a preset second temperature, and exhausting the heated air inside the washing compartment outside.
In one embodiment, the first temperature may be between 47°C and 53°C. The second temperature may be between 63°C and 67°C. The supplying steam in the performing of the washing cycle may be performed more than three times for 3 to 5 minutes. The supplying steam in the drying may be performed for more than 15 minutes.
Preferably, a control method of a dishwasher comprising a washing compartment, a sump configured to contain washing water, a steam generator and at least one spraying arm, the control method includes performing a washing cycle comprising spraying water to at least one rack provided in the washing compartment and supplying steam to the washing compartment until a temperature of the water reaches a preset first temperature, the spraying water and the supplying steam being repeated alternately in a state of a sump heater being turned off and a temperature of the water supplied to the washing compartment increasing over a preset temperature; and supplying steam to the washing compartment and exhausting air outside the washing compartment until a temperature of a dish placed in the washing compartment reaches a preset second temperature.
In one embodiment, the first temperature may be between 47°C and 53°C and the second temperature may be between 63°C and 67°C. The supplying steam in the performing of the washing cycle may be performed more than three times per 3 to 5 minute. The supplying steam in the drying may be performed for more than 15 minutes.
Preferably, a control method of a dishwasher including a washing compartment, a sump configured to contain water, a steam generator and at least one spraying arm, the control method may include spraying water to the washing compartment, with increasing a temperature of washing water by using steam; and supplying steam to the washing compartment to increase a temperature inside the washing compartment and exhausting air from inside the washing compartment to outside the washing compartment, the exhausting air being performed after the increase of the temperature inside the washing compartment in the supplying steam.
In embodiments, the temperature of the washing water may be increased by repeating the spraying water and the supplying steam alternatively. The spraying water and the supplying steam may be repeated alternatively more than three times. The temperature of the washing water may be increased gradually by the steam supplied to the washing compartment at the steam generator.
According to the control method of the dishwasher, washing efficiency may be secured without an operation of a sump heater provided in a sump containing washing or rinsing water. Also, wasted energy may be reduced.
Furthermore, in case of a dishwasher not including a sump heater, a temperature of washing or rinsing water may be increased by the steam. As a result, without the sump heater heating water, corresponding washing efficiency may be secured.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention.
In the drawings:

FIG. 1 is a sectional view schematically illustrating a dishwasher controlled according to an exemplary embodiment of a control method in accordance with an embodiment of the invention; and
FIG. 2 is a diagram schematically illustrating an overall operation of a dishwasher in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to the specific embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
FIG. 1 is a sectional view schematically illustrating a dishwasher controlled according to an exemplary embodiment of a control method in accordance with an embodiment of the invention; and
With reference to FIG. 1, a structure of the dishwasher will be explained. The dishwasher may include a case 100 defining an exterior appearance thereof, a door 120 capable of opening and closing allowing for access an interior of the case 100, a controller 102 to control the functioning of the dishwasher, and a control panel 130 mounted on the case 100 or door 120 so that a user may operate the dishwater.
In the case 100 may be provided a washing compartment 150 defined by a tub 110. Dishes may be placed in the washing compartment 150. A sump 200 is positioned under the tub 110. The sump is configured to contain water, such as washing and rinsing water. A washing pump 210 and a filter (not shown) may be provided in the sump 200. The washing pump 210 pumps the washing water held in the sump 200 and the filter (not shown) filters contaminated water. In addition, a sump heater 290 may be provided in the sump 200 to heat water that is collected and held in the sump 200.
A first water supply pipe 250 and a water drain pipe 270 may be connected with the sump 200. New clean water may be drawn from an external water source through the first water supply pipe 250 and the washing water inside the sump 200 may be drained outside through the water drain pipe 270. A first water supply valve 255 may be installed along the first water supply pipe 250 to control the supply of water to the sump 200.
At least one rack and spraying arm may be provided in the tub 110, specifically, in the washing compartment 150. Dishes are placed on the rack and the water pumped by the washing pump 210 is sprayed to the rack through the spraying arm.
Shown in FIG. 1, an upper rack 160 and a lower rack 170 are disposed in an upper portion and a lower portion of the washing compartment 150, respectively. An upper spraying arm 230 and a lower spraying arm 220 are disposed toward the upper rack 160 and the lower rack 170, respectively, to spray the water pumped by the washing pump 210. A top nozzle 240 may also be provided in the upper portion of the washing compartment 150 to spray the water pumped by the washing pump 210 downward.
Additionally, steam may be supplied to the washing compartment 150 by using the washing pump 210 and the spraying arms 230 and 220. A steam generator 300 may be further provided in the dishwasher, which may be operated separately from the sump heater 290. As illustrated in FIG. 1, the steam generator 300 is in communication with the first water supply pipe 250 and is in communication with the washing compartment 150 via a steam supply pipe 280. A second water supply valve 265 may be installed at a second water supply pipe 260 to control the supply of the water to the steam generator 300.
The steam generator 300 may include a steam heater 310 heating the water supplied to the steam generator 300 and a water level sensor 320 sensing a water level inside the steam generator 300. For example, the water level sensor 320 may sense a low level and a high level. The low level is predetermined to protect the steam heater 310 of the steam generator 300 from damage that might incur should the water level fall too low. The high level is predetermined to prevent the water supplied to the steam generator 300 from overflowing from the steam generator 300.
In addition, the steam generator 300 may include a steam supply valve (not shown) to control the flow of steam through the steam supply pipe 280 by opening and closing. This would provide for scheduled introduction of steam in accordance with a predetermined washing or steam cycle.
A pollution level sensor (not shown) may be provided at a predetermined portion of the sump 200 to measure a pollution level of the washing water circulated in the tub 110.
Additionally, the door 120 may include an exhaust fan 190 and an exhaust duct 192 to exhaust damp air from the washing compartment 150.
The controller 102 may control the dishwasher in accordance with predetermined instructions stored in a memory (not shown). The controller 102 may be operationally coupled with at least the control panel 130, the washing pump 210, and the steam generator 300 so that the they may be operated in accordance with a user's selection on the control panel 130.
The operational mode of the dishwasher may be determined according to a user's selection or a type of dishes being washed. Of course, the operational mode may also be predetermined according to a pollution level of the dishes to be washed. That is, a plurality of operational modes may be preprogrammed in the dishwasher in this exemplary embodiment. If the operational modes are preprogrammed, the number of rotations per minute of the motor and/or the amount of detergent may be determined according to the operational mode.
A control method and an operation of the dishwasher in accordance with an embodiment of the invention will now be described. The control method of the dishwasher may include performing washing, rinsing, and drying cycles. During the washing cycle, food scraps remaining on dishes are removed. Then once the washing cycle is complete, the dishes are rinsed during the rinsing cycle. The moisture remaining on the dishes may then be removed during the drying cycle. To perform a specific function, smaller processes may be performed intermittently among the three just mentioned processes.
The control method of the dishwasher of the exemplary embodiment will now be discussed in more detail. FIG. 2 is a diagram schematically illustrating overall operations of the dishwasher in accordance with an embodiment of the invention. The control method may include performing a preliminary wash cycle (P), performing a washing cycle (W), rinsing (R), and drying (D).
First, during the preliminary washing cycle (P), the water supplied from an external water source may be sprayed toward dishes in the washing compartment 150 without being heated by the sump heater 290. This preliminary washing cycle (P) may be performed to primarily remove food scraps on the dishes and soften any scraps that are not easily removed.
At this time, the water spraying of the preliminary washing cycle (P) includes supplying the water by using the upper spraying arm 230 (hereinafter, "upper spraying") and supplying the water by using the lower spraying arm 220 (hereinafter, "lower spraying"). The upper spraying and the lower spraying may be repeated alternately, any number of times, for a preset time period. For example, the upper spraying and the lower spraying may be repeated alternately for a number of minutes. The water used in the preliminary washing cycle (P) may be supplied from an external water supply source and may be, for example, cold water or warm water.
While warm water may tend to enhance the washing efficiency and reduce the washing time, it is preferable in this exemplary embodiment that warm water is not supplied or used at this step to save energy costs. Thus, as illustrated in FIG. 2, the water supplied to the dishwasher has its spraying process repeated without changes of the temperature (Tw) .
Once the performing of the preliminary washing cycle (P) is complete, the performing of the main washing cycle (W) may begin. In the main washing cycle (W), the supplying of the water (wsl, ws2, ws3) and the supplying of the steam (st1, st2, st3) may be repeated until a preset condition (w1) is satisfied for a preset time period.
The supplying of the water (wsl, ws2, and ws3) may separate or wash foreign matter from the dishes and the supplying of the steam (st1, st2, and st3) may soak and soften foreign matter stuck on surfaces of the dishes. The repeating of the steam supplying (st1, st2, st3...stn) and the water spraying (wsl, ws2, ws3...wsn) may gradually increase the temperature of the washing water. This occurs as the water that is sprayed into the washing compartment exchanges heat with the air containing the steam that is also introduced into the washing compartment 150.
The steam supplying (st1, st2, st3...stn) and the water spraying (wsl, ws2, ws3...wsn) may be repeated until the temperature of the washing water reaches a preset first temperature. Of course, the condition may also be preset based on a predetermined number of steam or washing repetitions, and not a predetermined temperature condition.
In addition, in one embodiment, each of the steam supplying steps (st1, st2, st3, ..., stn) may be performed for 3 to 5 minutes and may be performed more than three times. Thus, the steam supplying steps (st1, st2, st3, ..., stn) and the water spraying steps (wsl, ws2, ws3, ..., wsn) may be repeated alternately more than three times. Further, the water spraying steps (wsl, ws2, ws3, ..., wsn) may be performed using the upper and lower spraying arms 220 and 230.
Specifically, as illustrated in FIG. 2, an operation time (T(st)) of the steam supplying unit may be between 3 and 5 minutes. In FIG. 2, the steam supplying is repeated eleven times.
If the water to be used during the washing and rinsing cycle is heated by the sump heater 290 large qualities of energy may be consumed. Thus, according to the control method of this exemplary embodiment, the water is heated efficiently without the need for operation of the sump heater 290. Further, steam may be used to increase the temperature of the washing water, whether or not the sump heater 290 is provided or activated.
The temperature of the washing water heated by the steam in the washing cycle (W) may be near approximately 50°C. As illustrated in FIG. 2, the upper spraying arm and the lower spraying arm, that are provided in the washing compartment, may spray the water alternately in a predetermined interval in each water spraying step (wsl, ws2, ws3, ..., wsn). The first temperature (T1) may be in a range between 47°C and 53°C to make it possible to wash the dishes efficiently.
Once the washing cycle (W) is complete, the washing water used in the washing cycle (W) may be drained and new water may be added and used during the rinsing cycle (R) . The rinsing (R) may be performed once with the new water that has been supplied. However, where necessary, the water draining and new water supplying steps may be repeated several times to ensure the rinsing cycle (R) sufficiently rinses the dishes with new, clean water.
As illustrated in FIG. 2, the rinsing cycle (R) may include a first rinsing step (r1) and a second rinsing step (r2). The temperature of the washing water (washing temperature), which has increased gradually while steam was introduced during the washing cycle (W) may then decrease gradually during the rinsing cycle (R). The washing temperature decreases because the steam supply has stopped, the sump heater 290 is turned off, and new water is being supplied. It may be preferable during the rinsing cycle (R), to spray the water by alternately using the upper and lower spraying arms, similar to the washing cycle (W), for a preset time period.
Once the rinsing cycle (R) is complete, the drying cycle (D) may begin. The drying cycle (D) may include increasing the washing temperature by supplying steam to the washing compartment 150 (d1), until the temperature of the dishes contained therein reaches a preset second temperature (T2). The drying cycle (D) may also include exhausting damp air from inside the washing compartment 150 to outside (d2). Steam generated at the steam generator may again be supplied to the washing compartment 150. The temperature of the dishes contained in the washing compartment 150 may then be heated by the steam, without any need for an auxiliary heater.
The temperature inside the washing compartment 150 is represented by the graph of FIG. 2 for time period D as a dotted curved line A. The solid curved line in the same figure is for period D and represents the temperature of the washing water or the temperature of the sump heater containing the washing water. The completion of the heating process during the drying cycle may be determined by the temperature inside the washing compartment 150, for example.
In one embodiment, the time (T(d1)) that steam is supplied during the heating period (d1) may be more than 15 minutes. While steam is supplied to the washing compartment 150 by the steam generator 300, water may be supplied to the steam generator 300.
In one embodiment, the second temperature (T2) may be in a range between 63°C and 67°C. This range of the temperature makes it possible to dry the dishes via the exhaust (d2) of the heated air following the heating cycle (D). Thus, if the temperature inside the washing compartment 150 reaches the second temperature, the exhaust fan 190 is initiated to exhaust damp air from the washing compartment 150, such that the dishes may be dried efficiently. The moisture remaining on the dishes in the rinsing cycle (R) may be evaporated during the heating (r1) of the drying cycle (D) and the moisture may be exhausted via the exhaust process (d2).
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

A control. method of a dishwasher comprising a washing compartment (150) to receive dishes therein, a sump (200) configured to contain water, a steam generator, at least one rack, and at least one spraying arm (220, 230), the method comprising:
performing a washing cycle including the steps of:
spraying water toward the rack, and

supplying steam to the washing compartment, wherein the steps of spraying water and supplying steam are repeated alternately until a temperature of the water reaches a preset first temperature; and

performing a drying cycle,

characterized in that

the step of performing the drying cycle includes:
heating the washing compartment by introducing steam into the washing compartment until an internal temperature of the washing compartment reaches a preset second temperature, and

exhausting the heated air from the washing compartment to an outside of the washing compartment once the preset second temperature is reached.
The control method of claim 1, wherein the first temperature is between 47°C and 53°C.
The control method of claim 1, wherein the second temperature is between 63°C and 67°C.
The control method of claim 1, the step of supplying steam during the washing cycle further comprising:
supplying steam in at least three cycles, wherein each cycle lasts a period of 3 to 5 minutes.
The control method of claim 1, the step of supplying steam during the washing cycle further comprising:
supplying steam for a period of at least than 15 minutes.