WO2009028786A1

WO2009028786A1 - A method of controlling a dishwashing machine having a steam generator

Info

Publication number: WO2009028786A1
Application number: PCT/KR2008/003110
Authority: WO
Inventors: Jung Youp Han; Yong Jin Choi; Joon Ho Pyo; Young Hwan Park; Seong Ho Kim
Original assignee: Lg Electronics Inc.
Priority date: 2007-08-31
Filing date: 2008-06-04
Publication date: 2009-03-05
Also published as: US20090056752A1; KR20090022733A

Abstract

A method of controlling a home appliance, such as as dish washing machine, that includes supplying steam in a washing operation is disclosed. The method includes supplying steam generated by a steam generator (300), and supplying water to a water tank (330) of a steam generator (300) such that water overflows the water tank (330) of the steam generator (300) before and/or after steam is supplied to the washing chamber.

Description

A METHOD OF CONTROLLING A DISHWASHING MACHINE HAVING A STEAM GENERATOR

Technical Field

[1] The disclosure relates to home appliances, and more particularly to a method of controlling a home appliance, and even more particularly to a method of controlling dish washing machine, which prevents a steam generator from malfunctioning while promoting efficient washing via use of steam. Background Art

[2] Generally, a dish washing machine is an apparatus that automatically washes items, such as items disposed in a washing compartment, by spraying wash water toward the items at a high pressure to remove foreign matter, such as food particles and residues, which may be attached to surfaces of the items to be washed.

[3] One of the important factors associated with the dish washing machine relates to washability in association with removing foreign matter attached to the surfaces of items to be washed. In order to improve washability, it is necessary to increase a force required to remove foreign matter from the surfaces of items, namely, a spray pressure of the wash water. Disclosure of Invention Technical Problem

[4] However, when the spray pressure of the wash water is excessively high, items in the dish washing machine, such as dishes, may be damaged or even broken. Further, when the items are washed at a high spray pressure, the amount of the wash water required to wash the items increases. Furthermore, even if the wash water is sprayed at the items at a high spray pressure, it may still be difficult to remove foreign matter from the items.

[5] Steam may be used in dish washing, however, when steam is generated from "Hard water" unwanted matter, such as lime, may accumulate in a water tank of the steam generator and cause the steam generator to malfunction. Technical Solution

[6] Accordingly, a controlling method of a dish washing machine that substantially obviates one or more problems due to limitations and disadvantages of the related art is highly desirable.

[7] Accordingly, a method of controlling a dish washing machine that applies steam to a wash and prevents a steam generator from malfunctioning due to accumulation of unwanted matter in the water tank of the steam generator is highly desirable.

[8] At least one advantage of the present invention is to provide a method of controlling a dish washing machine capable of efficiently using wash water for washing dishes. [9] Advantages and features will be set forth in part in the description that 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 aforementioned advantages and features may be realized and attained by the exemplary structures and methods described in the written description, claims, and appended drawings.

Advantageous Effects

[10] A method of controlling a dish washing machine achieves at least the following effects and advantages. [11] First, there is an advantage of performing a method to prevent a steam generator from malfunctioning due to unwanted matter in the water tank of the steam generator by discharging the unwanted matter remaining in the steam generator the water tank of the steam generator before or after steam is generated. [12] Second, it is possible to use or reuse the wash water containing unwanted matter to wash the dishes by supplying water discharged from the steam generator to a tub or a sump of the dish washing machine. Thus, there is an advantage of reducing the amount of water used to wash the dishes. [13] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and should not be construed as limiting the scope of any claim.

Brief Description of the Drawings [14] The accompanying drawings, which are included to provide a further understanding of the embodiments described herein, are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings: [15] FIG. 1 illustrates a cross-sectional view of a dish washing machine capable of performing a method according to an embodiment of the invention. [16] FIG. 2 illustrates a washing process according to an embodiment of the invention, which may be performed in the dish washing machine of FIG. 1. [17] FIG. 3 illustrates a cross-sectional view of a dish washing machine capable of performing another method according to an embodiment of the invention.

Best Mode for Carrying Out the Invention [18] Reference will now be made in detail to the preferred embodiments, 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. [19] A configuration of a dish washing machine according to one embodiment of the invention will be described with reference to FIG. 1.

[20] The dish washing machine may include, for example, a case 100 forming an exterior of the dish washing machine, a door 120 opening and closing the case 100, and a control panel 130 mounted to the case 100 or the door 120 to enable a user to operate the dish washing machine, and a controller 132 and associated memory 134 to control the dish washing machine and store instructions and data, respectively. The controller 132 may be operationally coupled to electrically-operated parts, such as switches or a keyboard (not shown) on the control panel 130, a pump 210, a steam generator 300, valves 255, 265, and sump heater 290. The controller 132 and associated memory 134 may control the operation of the dish washing machine.

[21] A tub 110 is disposed in the case 100 to define a washing compartment 150 in the case 100 as a space that accommodates items, such as dishes, to be washed. A sump 200 for storing the wash water is arranged below the tub 110.

[22] The sump 200 includes a pump 210 for pumping the wash water stored in the sump

200. The sump may also include a filter (not shown) for filtering contaminated wash water. Further, a sump heater 290 may also be disposed in the sump 200, to heat the wash water stored in the sump 200.

[23] A first water supply tube 250 may be connected to the sump 200 to supply fresh water from an external water supply source to the sump 200. A water drain tube 270 may also be connected to the sump 200 to drain the wash water from the sump 200 to the outside of the dishwasher. A first water supply valve 255 to control the supply of water to the sump 200 may be installed on the water supply tube 250.

[24] At least one rack, such as rack 160, 170 may be arranged in the tub 110, namely, in the washing compartment 150. At least one spray arm 220, 230 may also be arranged in the washing compartment 150 to spray the water pumped by the pump 210 toward the at least one rack 160, 170.

[25] In the exemplary embodiment illustrated in FIG. 1, an upper rack 160 and a lower rack 170 are arranged at upper and lower portions of the washing compartment 150, respectively, and an upper spray arm 230 and a lower spray arm 220 are arranged to spray water, pumped by the pump 210, toward the upper rack 160 and the lower rack 170, respectively.

[26] In addition, a top nozzle 240 may be arranged at an upper portion of the washing compartment 150. The top nozzle 240 functions to spray the water, pumped by the pump 210, from the upper portion of the washing compartment 150 to a lower portion thereof.

[27] A dish washing machine according to the present invention may be configured not only to spray the wash water into the washing compartment 150 by the pump 210 and the spray arms 220, 230, and top nozzle 240, but also to spray or supply steam to the washing compartment 150. For this, the dish washing machine according to the present invention includes a steam generator 300 which may be operated independently of the sump heater 290 disposed in the sump 200.

[28] As shown in FIG. 1, the steam generator 300 may communicate with the first water supply tube 250 via the second water supply tube 260. The steam generator 300 also may communicate with the washing compartment 150 of the tub 110 via a steam supply tube 280. A second water supply valve 265 for controlling the supply of water to the steam generator 300 may be installed on the second water supply tube 260.

[29] The steam generator 300 may include a water tank 330, which stores water supplied into the steam generator 300, a steam heater 310 which heats the water stored in the water tank 330, and a water level sensor 320, which senses the water level of the water in the water tank 330 of the steam generator 300. The water level sensor 320 can sense, for example, a low water level and a high water level.

[30] The low water level may be set to protect the steam heater 310 in the steam generator

300 from, for example, becoming exposed to air. The high water level may be set to prevent the water supplied into the steam generator 300 from overflowing the water tank 330 when, for example, the steam generator 300 is operated.

[31] Referring to FIGs. 1 and 2, a process of washing items in a washing compartment, according to an embodiment of the invention, is provided.

[32] The process performed in the dish washing machine may include a preliminary washing cycle P, a main washing cycle M, a rinsing cycle R, and a drying cycle D. FIG. 2 also includes a period I, which denotes a time period before a process is performed in the dish washing machine.

[33] The preliminary washing cycle P may include washing the items using wash water without a detergent. The main washing cycle M may include washing the items using wash water with a detergent. The rinsing cycle R may include washing the items by spraying wash water onto the items after the main washing cycle M. The drying cycle D may include drying the dishes using heated air or non-heated air.

[34] First, in the preliminary washing cycle P, water may be supplied to the items to be washed without heating the water in the sump 200. The preliminary washing cycle P may be performed as a first attempt to remove foreign matter attached to the items being washed.

[35] In one embodiment, the upper spray arm 230 and the lower spray arm 220 may be alternately supplied with water to spray the water onto the items being washed. That is, a water spraying action performed in the preliminary washing cycle P may include an upper water spraying action for supplying water through the upper spray arm 230 and a lower water spraying action for supplying water through the lower spray arm 220. The spraying actions may be performed repeatedly. The spraying actions may alternate between the upper spray arm 230 and the lower spray arm 220. They may be performed for the same, or different, time intervals. For example, the upper water spraying action and the lower water spraying action may alternately be performed for one minute each.

[36] In one embodiment, during the preliminary washing cycle P, the steam heater 310 and the sump heater 290 may be maintained in an off state. In this state, an inner temperature of the washing compartment 150, into which the wash water is sprayed, is substantially the same as the temperature of the water supplied into the sump 200 from the outside.

[37] Also, heated washing water, with or without detergent, or unheated washing water, with or without detergent, may be supplied in the preliminary washing cycle P according to the present invention without departing from the scope of the invention.

[38] After the preliminary washing cycle P is completed, the main washing cycle M may be performed. The main washing cycle M may include a first main washing step Ml for spraying heated wash water onto items, a second main washing step M2 for alternately spraying steam and wash water onto the items, and a third main washing step M3 for spraying heated wash water to the items.

[39] At the first main washing step Ml, the wash water heated by the sump heater 290 may be supplied to the items being washed after a first set period of time following completion of the preliminary washing cycle P (S20).

[40] Specifically, the wash water heated by the sump heater 290 may be pumped to the upper spray arm 230 and the lower spray arm 220 by the pump 210 to alternately and repeatedly spray the items to be washed.

[41] In this case, the steam heater 310 may be maintained in an off state. The first set period of time may be stored in the controller 132 and/or associated memory 134 in advance. In other words, the first set period of time may be preset.

[42] At the second main washing step M2, the steam and wash water are alternately supplied for a second set period of time after the first main washing step Ml is completed. In other words, at the second main washing step M2, a steam spraying action for supplying steam to the items to be washed and a water spraying action for supplying wash water to the items to be washed are repeatedly and alternately performed a predetermined number of times and/or for a predetermined time period.

[43] In this case, the water spraying action functions to remove foreign matter attached to the items. The steam spraying action functions to steep foreign matter in steam such that the attachment between the foreign matter and the item being washed (e.g., rice residue and a dish, respectively) is weakened and the foreign matter attached to the item can be removed more easily than if the foreign matter were not steeped in steam.

[44] Further, in the steam spraying action, the steam heater 310 for generating steam may be maintained in an on state. In the water spraying action, the steam heater 310 may be in an off state. At the second main washing step M2, the sump heater 290 may be turned off, and the steam heater 310 for generating steam may be periodically powered on and off to alternately supply the wash water and steam to the items to be washed for the second set period of time.

[45] In this case, since the sump heater 290 may be maintained in an off state, unheated wash water may be supplied to the items to be washed through the upper spray arm 230 and the lower spray arm 220 during the water spraying action. In this case, since the supplied water may be used without being additionally heated in the second main washing step M2, there is an advantage of reducing power consumption.

[46] At the third main washing step M3, the wash water heated by the sump heater 290 may be supplied to the items to be washed for a third set period of time after the second main washing step M2 is completed.

[47] Specifically, the wash water heated by the sump heater 290 may be pumped to the upper spray arm 230 and the lower spray arm 220 by the pump 210 to alternately spray the items. In this case, the steam heater 310 may be maintained in an off state.

[48] When the main washing cycle M is completed, the circulated wash water may be discharged to the outside through the water drain tube 270, and the rinsing cycle R for supplying fresh water to the items to be washed may begin. In the rinsing cycle R, wash water may be supplied to the items to be washed. Generally, the wash water may be supplied in an unheated state.

[49] Further, when the rinsing cycle R is completed, the drying cycle D performs a drying operation by supplying, for example, heated air or non-heated air, to the items.

[50] Meanwhile, when the steam is generated using the steam generator 300, unwanted matter may accumulate in the water tank 330 for the following reason: if the hardness of the water supplied into the steam generator 300 is high, calcium hydrogen carbonate (Ca(HCO₃)₂) dissolved in the water may be precipitated in the form of lime (calcium carbonate (CaCO₃) and the like) when the water is heated. Particularly, such a phenomenon typically occurs in Europe and in American continental areas because water used in these areas is considered hard water having a high hardness factor.

[51] Further, the amount of unwanted matter, such as lime (calcium carbonate CaCCβ and the like), deposited in the water tank 330 increases as the steam spraying action is repeated and/or increasingly used. When the amount of the water present in the water tank 330 is small, the concentration of unwanted matter typically increases, which may cause damage to the steam heater 310 and malfunction of the steam generator 300. This is because the steam heater 310 may be corroded by lime.

[52] Accordingly, it is preferable to remove calcium and magnesium ions and the like dissolved in the residual water in the water tank 330 in advance, thereby preventing precipitation of lime and the like.

[53] For this, a method of controlling the dish washing machine includes an unwanted matter discharging step of discharging unwanted matter from the steam generator 300 by oversupplying water into the water tank 330 of the steam generator 300 at step S20 before a washing process for washing the items using the steam generated by the steam generator begins or at step SlO after the washing process is completed.

[54] In this case, the washing process may include all cycles, regardless of whether the cycle is enabled to use steam. For example, the washing process may include a preliminary washing cycle, a main washing cycle, and a rinsing cycle.

[55] Further, the unwanted matter discharging step performed after the washing process is completed may be performed at the same time a drying cycle D is performed and after the rinsing cycle is completed (SlO).

[56] In order to discharge unwanted matter outside of the steam generator, the controller

132 and associated memory 134 may cause water to be supplied to the water tank 330 in a predetermined amount or for a preset period of time. In this case, the predetermined amount or the preset period of time may be set based on information including the volume of the water tank 330.

[57] The additionally-supplied water may be introduced into the sump 200 or the tub 110 together with the water present in the water tank 330. Thus, according to one exemplary embodiment, the water supplied into the water tank 330 may be supplied to overflow from the water tank 330 into the sump 200 or the tub 110.

[58] Water overflowing the water tank 330 may be introduced into the tub 110 or the sump 200 through the steam supply line 280. The steam supply line 280 serves to introduce the steam to the tub 110 and also serves to introduce the water overflowing the water tank 330 into the tub 110 or the sump 200.

[59] In this embodiment, the steam supply line 280 may be installed at the upper portion of the water tank 330 to be connected to the tub 110. When unwanted matter is discharged from the water tank 330, the water tank 330 maintains a full water level. As a result, water may be oversupplied to the water tank 330 before and/or after the washing process, including the steam spraying action, and the supplied water, with unwanted matter from the water tank 330, may be discharged from the steam generator 300.

[60] Meanwhile, the unwanted matter discharging step may be performed at the same time the preliminary washing cycle P may be performed and before the main washing cycle M (Sl). Further, the unwanted matter discharging step may be performed at the same time the rinsing cycle R and after the main washing cycle M is completed (S2). The unwanted matter discharging step may be performed at the same time, for example, as a heating and rinsing cycle may be performed after the main washing cycle M is completed (S2). In this case, the heating and rinsing cycle may be a process of rinsing the items while spraying steam and water after the main washing cycle M is completed.

[61] Meanwhile, the unwanted matter discharging step may be performed at step S7 before the steam spraying action for supplying the steam generated by the steam generator 300 to the items and/or at step S 8 after the steam is supplied. Also in this case, the water supplied at the unwanted matter discharging step may be supplied to the water tank 330 to overflow the water tank 330.

[62] Further, the unwanted matter discharging step may be performed at step S3 before the second main washing step M2 or at step S4 after the second main washing step M2.

[63] Referring to FIG. 3, a dish washing machine according to another embodiment of the present invention is explained.

[64] The dish washing machine according to this embodiment is similar in some respects to the dish washing machine of the first described embodiment. Thus, the same components are designated by the same reference numerals and the detailed description thereof is omitted.

[65] However, the dish washing machine according to this embodiment includes auxiliary water drain tubes 360 and 380 disposed separately from the steam supply line 280, different from the above-described embodiment. The auxiliary water drain tubes 360 and 380 include a first auxiliary water drain tube 360 for draining water in the steam generator 300 to the outside of the dish washing machine and a second auxiliary water drain tube 380 for introducing water in the steam generator 300 to the tub 110 or the sump 200.

[66] Further, a flow control valve 350 for controlling the flow of water may be installed at a point of connecting the first auxiliary water drain tube 360 and the second auxiliary water drain tube 380. The flow control valve 350 may be configured to selectively open and close the auxiliary water drain tubes 360, 380 in a number of different combinations. For example, the flow control valve 350 may be any valve capable of selectively opening and closing the first auxiliary water drain tube 360 and the second auxiliary water drain tube 380. The flow control valve 350 may be capable of closing both the first auxiliary water drain tube 360 and the second auxiliary water drain tube 380.

[67] Further, a water drain pump 340 for discharging water to the auxiliary water drain tubes may be installed between the flow control valve 350 and the steam generator 300.

[68] Further, a steam control valve 285 may be installed on the steam supply tube 280, which introduces the steam generated in the steam generator 300 to the tub 110 or the sump 200. [69] A method of controlling the exemplary embodiment of the dish washing machine of

FIG. 3 is described below.

[70] When a washing step of washing the items using steam is performed, the steam generated by the steam generator may be introduced or sprayed into the washing compartment.

[71] In this case, the steam supply tube 280 for introducing the steam to the washing compartment 150 may be maintained in an open state. The auxiliary water drain tubes 360 and 380 are maintained in a closed state. That is, the steam control valve 285 installed on the steam supply tube 280 may be maintained in an open state. The flow control valve 350 installed on the auxiliary water drain tubes 360, 380 close both the first auxiliary water drain tube 360 and the second auxiliary water drain tube 380.

[72] Then, the steam generated by the steam generator 300 may be supplied into the tub

110 in a state where the water of the steam generator 300 is not discharged through the auxiliary water drain tubes 360 and 380. In this case, the steam supply tube 280 may be installed at an upper portion of the water tank 330. The auxiliary water drain tubes 360 and 380 may be installed at a position on the water tank 330 that is lower than a position of the steam supply tube 280 on the water tank 330.

[73] After and/or before the washing process, the unwanted matter discharging step may be performed to discharge unwanted matter from the water tank 330 of the steam generator 300 to a space outside of the water tank 330 of the steam generator 300.

[74] In the same respect, the unwanted matter discharging step may be performed before and/or after the main washing cycle, the second main washing step and the steam spraying action.

[75] In this case, water may be supplied to the water tank 330 in a state where the steam supply line 280 is closed. Then, the flow control valve 350 opens at least one of the first auxiliary water drain tube 360 and the second auxiliary water drain tube 380. Then, the water remaining in the steam generator 300 may be discharged outside of the steam generator 300 with the additionally supplied water. In this case, any unwanted matter within the steam generator 300 may also discharged outside of the steam generator 300.

[76] When only the first auxiliary water drain tube 360 is opened, water is introduced into the tub 110 again. When only the second auxiliary water drain tube 380 is opened, the water is discharged to the outside of the dish washing machine. Further, the water drain pump 340 may be operated to discharge water from the water tank 330. In this case, substantially all of the water remaining in the water tank 330 may be emptied from the water tank 330 of the steam generator 300.

[77] It will be apparent to those skilled in the art that various modifications and variations can be made from the embodiments described herein without departing from the spirit or scope of the inventions. Thus, it is intended that the claims appended hereto cover the modifications and variations. [78]

Claims

[1] A method of controlling a dish washing machine comprising: operating a process configured to wash items using steam generated by a steam generator; and discharging unwanted matter from the steam generator before or after a washing cycle of the process by oversupplying water to a water tank of the steam generator. [2] The method of claim 1, wherein the unwanted matter in the water tank is discharged from the steam generator by the water supplied to the water tank for a predetermined time without operating the steam generator. [3] The method of claim 1, wherein the water tank is filled with water while the unwanted matter is discharged from the steam generator. [4] The method of claim 1, wherein the unwanted matter and the water discharged from the water tank of the steam generator are introduced into a sump or a tub of the dish washing machine. [5] The method of claim 1, wherein the water in the water tank is discharged through a water discharge tube which is provided at the steam generator separately from a steam supply tube. [6] The method of claim 5 further comprising: controlling a discharge valve provided on the water discharge tube to selectively control the flow of discharged water and unwanted matter. [7] The method of claim 6, wherein controlling the discharge valve comprises: closing the discharge valve during the washing process; and opening the discharge valve during discharge of unwanted matter from the steam generator. [8] A method of controlling a dish washing machine comprising: performing a steam spraying action within a washing chamber, wherein the steam is generated by a steam generator; and discharging unwanted matter from the steam generator before or after the steam spraying action by oversupplying water to a water tank of the steam generator. [9] The method of claim 8 further comprising: introducing the discharged water and unwanted matter from the water tank into a sump or a tub of the dish washing machine. [10] The method of claim 8, wherein the water supplied to the water tank of the steam generator is a predetermined amount of water, or an amount of water released during a predetermined time period, the supplied water discharging unwanted matter from the water tank of the steam generator. [11] The method of claim 10, wherein the predetermined amount of the water or the predetermined time period is set based on information including a volume of the water tank of the steam generator. [12] The method of claim 9, wherein the discharged water is introduced into the sump or the tub through a steam supply tube provided at the steam generator. [13] A method of controlling a dish washing machine comprising: performing a main washing cycle that applies water with a detergent and steam, wherein the steam is generated by a steam generator; and discharging unwanted matter from the steam generator before or after the main washing cycle, wherein the steam generator discharges unwanted matter when the steam generator receives water in excess of a capacity of a water tank of the steam generator. [14] The method of claim 13, further comprising: performing a preliminary washing cycle prior to performing the main washing cycle, wherein unwanted matter is discharged during the preliminary washing cycle. [15] The method of claim 13 further comprising: performing a rinsing cycle after the main washing cycle, wherein unwanted matter is discharged during the rinsing cycle. [16] The method of claim 13, further comprising: performing a drying cycle, wherein unwanted matter is discharged during the drying cycle. [17] The method of claim 13, wherein the water tank is filled with water before or after the main washing cycle. [18] The method of claim 13, further comprising: emptying the water tank of water. [19] The method of claim 18, wherein the water in the water tank is removed through a discharge tube which is provided at the steam generator separately from a steam supply tube of the steam generator. [20] A method of controlling a dish washing machine comprising: performing a first main washing step that includes washing with heated water; performing a second main washing step that includes washing with water with a detergent and steam, wherein the water with a detergent and steam are sprayed at selective time periods; and discharging unwanted matter from the steam generator before or after the second main washing step by overflowing a water tank of the steam generator.