Patent Description:
A dishwasher is a household appliance for washing up dirt such as food wastes on the dishes or the cooking utensils (hereinafter, referred to as 'washing object') by high-pressure washing water sprayed from a spray arm.

The dishwasher generally includes a tub forming a washing chamber and a sump mounted on the bottom of the tub to store the washing water. Then, the washing water is moved to the spray arm by the pumping operation of a washing pump installed inside the sump, and the washing water moved to the spray arm is sprayed at high pressure through a spray hole formed in the spray arm. Then, the washing water sprayed at a high pressure impinges against the surface of the washing object, so that the dirt on the washing object falls to the bottom of the tub.

Meanwhile, the dishwasher performs washing of the washing object by using a heated washing water or performs sterilization by supplying steam to the washing object. Conventional dishwashers generally generate hot water or steam by heating washing water stored in the sump through a heater provided inside the sump. In this case, since the heater should be exposed to the inside of the sump to contact the washing water, the water level inside the sump should be controlled so that the heater is not exposed to prevent overheating of the heater. In addition, since the heat transfer is possible only when the heater is in contact with the washing water, there exists a problem in that the heat exchange efficiency is lowered as foreign matter adheres to the surface of the heater and durability is deteriorated as the surface of the heater is corroded.

In order to overcome such disadvantages, a dishwasher in which a heater is installed on a pump has recently been developed. In this case, the heater heats the washing water inside the pump to generate hot water or steam. Control is required to appropriately achieve generation of steam through such a washing pump.

<CIT> relates to a dishwasher which is capable of supplying steam evenly to washing objects placed in front or rear portions of a rack, and a control method thereof.

<CIT> relates to a control method of a dishwasher, which can achieve an improvement in washing performance via supply of steam.

<CIT> relates to a dishwasher capable of spraying steam through a spray arm and a method of controlling a dishwasher that sprays steam to perform a drying cycle.

<CIT> relates to a dishwasher and a control method for a dishwasher.

<CIT> relates to a steam generator sensing abnormal scale of a heater mounted therein.

The present invention has been made in view of the above problems, and provides a control method for a dishwasher in which steam is generated appropriately by controlling a washing pump. The scope of the present invention is defined by the appended independent claim, which relates to a control method for a dishwasher , with further preferred features of the invention defined by the dependent claims. In the following, when referring to a dishwasher, this dishwasher is related to the claimed control method for a dishwasher, but not as such forming part of the claimed scope of the invention.

In accordance with an aspect of the present invention, a method of controlling a dishwasher includes: a steam supply step of supplying washing water to the sump from an external water source; and a steam generation step of maintaining a water level of the washing water existing inside the washing pump at a certain water level or higher and heating the washing water.

The method further includes a sump washing step of supplying the washing water to the sump from an external water source before the steam supply step and then draining the washing water supplied to the sump.

In the sump washing step, the washing pump does not operate.

The water level of the washing water supplied to the sump in the water supply for steam step is lower than the water level of the washing water supplied to the sump in the sump washing step.

The washing pump includes a steam discharge pipe connected to the steam nozzle to discharge steam generated therein, and an amount of washing water supplied to the sump in the steam supply step is set so that the water level of the washing water when flowing into the washing pump is lower than a lowermost end of the steam discharge pipe.

The method further includes: a washing process step of spraying the washing water on a washing object to remove dirt attached to the washing object; and a steam washing process step of discharging steam to the washing object, wherein the steam washing process step comprises the steam supply step and the steam generation step, wherein the water level of the washing water supplied to the sump in the steam supply step is lower than the water level of the washing water supplied to the sump in the washing process step.

The plurality of spray arms are disposed vertically, wherein the washing pump is connected to a spray arm which is disposed at an uppermost end of the plurality of spray arms in the steam generation step.

The method further includes: a hot water circulation step for heating the washing water and sending the washing water to at least one of the plurality of spray arms by the washing pump, before the steam generation step.

In the steam generation step, when the hot water circulation step is completed, the water level of the washing water existing inside the washing pump is maintained at a certain level or higher and the heated washing water stored in the washing pump is heated to generate steam.

Execution time of the steam generation step is longer than execution time of the hot water circulation step.

The hot water circulation step and the steam generation step are repeatedly performed.

A temperature at which the washing pump heats the washing water in the steam generation step is higher than a temperature at which the washing pump heats the washing water in the hot water circulation step.

The washing pump sends the washing water to all of the plurality of spraying arms in the hot water circulation step.

The dishwasher further includes: a check valve which is disposed between the sump and the washing pump, wherein the check valve is opened to allow the washing water to flow from the sump to the washing pump in the hot water circulation step.

In accordance with another aspect of the present invention, not forming part of the claimed scope, a dish washer includes: a tub which accommodates a washing object; a plurality of spray arms which spray washing water into the tub and are disposed vertically; a sump which stores the washing water; a washing pump comprising an impeller which sends the washing water stored in the sump and a washing motor which rotates the impeller; a heater which heats the washing water inside the washing pump; and a controller which controls the washing motor and the heater, wherein the controller operates the heater to generate steam while maintaining water level of the washing water existing inside the washing pump at a certain level or higher.

The dish washer further includes: a switching valve which selectively connects the washing pump with at least one of the plurality of spray arms, wherein the controller controls the switching valve to connect the washing pump to a spray arm which is disposed at an uppermost end of the plurality of spray arms, when generating the steam.

The controller operates the washing motor and the heater simultaneously to spray heated washing water through at least one of the plurality of spray arms and then operates the heater to generate steam in a state of maintaining the water level of the washing water existing inside the washing pump at a certain level or higher.

The dish washer further includes: a check valve disposed between the sump and the washing pump, wherein the check valve is opened to allow the washing water to flow from the sump to the washing pump when the washing motor operates, and is closed to allow the washing water to be stored inside the washing pump when the washing motor is stopped.

The dish washer further includes: a water supply valve which intermits washing water supplied from an external water source; and a draining pump which drains the washing water stored in the sump to the outside, wherein the controller opens the water supply valve to supply the washing water from the external water source to the sump, and then operates the draining pump to drain the washing water supplied to the sump, wherein the controller does not operate the washing motor and the heater from the opening of the water supply valve to the operation of the draining pump.

The objects, features and advantages of the present invention will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which:.

Exemplary embodiments of the present invention are described with reference to the accompanying drawings in detail. The same reference numbers are used throughout the drawings to refer to the same or like parts. Detailed descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention.

Hereinafter, the present invention will be described with reference to the drawings for explaining a dishwasher and a controlling method therefor according to embodiments of the present invention.

<FIG> is a schematic structural view of a dishwasher according to an embodiment of the present invention, and <FIG> is a configuration view of a dishwasher according to an embodiment of the present invention.

The dishwasher <NUM> according to an embodiment of the present invention includes a case <NUM> that forms an outer appearance, a tub <NUM> that is provided inside the case <NUM> and forms a washing chamber 12a in which a washing object is accommodated, a door <NUM> that is provided on the front surface of the tub <NUM> and opens and closes the washing chamber 12a, a sump <NUM> that is disposed below the tub <NUM> and stores washing water, a plurality of spray arms <NUM>, <NUM>, <NUM> that spray washing water into the tub <NUM>, a washing pump <NUM> that sends washing water stored in the sump <NUM> to the plurality of spray arms <NUM>, <NUM>, <NUM>, a heater <NUM> that heats the washing water inside the washing pump <NUM>, a check valve <NUM> that is disposed between the sump <NUM> and the washing pump <NUM> and opened to allow the washing water to flow from the sump <NUM> to the washing pump <NUM>, a steam nozzle <NUM> that is provided in the door <NUM> and discharges the steam generated in the washing pump <NUM> into the tub <NUM>, a switching valve <NUM> that selectively connects the washing pump <NUM> to at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>, a water supply valve <NUM> that supplies the washing water from an external water source to the sump <NUM>, a flow meter <NUM> that measures the flow rate of the washing water supplied from the external water source to the sump <NUM>, and a draining pump <NUM> that drains the washing water stored in the sump <NUM> to the outside,.

The tub <NUM> is formed in a hexahedron shape having an opened front surface and forms a washing chamber 12a therein. A communication hole 12c through which the washing water flows into the sump <NUM> is formed in a bottom 12b of the tub <NUM>. The washing chamber 12a is provided with a plurality of racks <NUM> and <NUM> for receiving the washing object. The plurality of racks <NUM> and <NUM> include a lower rack <NUM> disposed at a lower portion of the washing chamber 12a and an upper rack <NUM> disposed at an upper portion thereof. The lower rack <NUM> and the upper rack <NUM> are vertically spaced apart and can be slid forwardly of the tub <NUM> to be drawn out.

The plurality of spray arms <NUM>, <NUM>, and <NUM> are disposed in the vertical direction. The plurality of spray arms <NUM>, <NUM>, and <NUM> include a lower spray arm <NUM> which is disposed in the lowermost end and sprays washing water from the lower side to the upper side toward the lower rack <NUM>, an upper spray arm <NUM> which is disposed in the upper side of the lower spray arm <NUM> and sprays washing water from the lower side to the upper side toward the upper rack <NUM>, and a top spray arm <NUM> which is disposed in the upper end of the washing chamber 12a that is above the upper spray arm <NUM> and sprays washing water from the upper side to the lower side.

The plurality of spray arms <NUM>, <NUM>, and <NUM> are supplied with the washing water from the washing pump <NUM> through a plurality of spray arm connecting flow paths <NUM>, <NUM>, and <NUM>. The plurality of spray arm connecting flow paths <NUM>, <NUM>, and <NUM> include a lower spray arm connecting flow path <NUM> connected to the lower spray arm <NUM>, an upper spray arm connecting flow path <NUM> connected to the upper spray arm <NUM>, and a top spray arm connecting flow path <NUM> connected to the top spray arm <NUM>.

The sump <NUM> is disposed below the bottom 12b of the tub <NUM> to collect washing water. The sump <NUM> is connected to a water supply flow path <NUM> through which washing water supplied from an external water source flows. The water supply flow path <NUM> is provided with the water supply valve <NUM> for intermitting washing water supplied from the external water source. When the water supply valve <NUM> is opened, the washing water supplied from the external water source flows into the sump <NUM> through the water supply flow path <NUM>. The water supply flow path <NUM> is provided with a flow meter <NUM> for measuring the flow rate of the washing water flowing into the sump <NUM> through the water supply flow path <NUM>.

The sump <NUM> is connected to a drainage flow path <NUM> for guiding the stored washing water to the outside of the dishwasher <NUM>. The drainage flow path <NUM> is provided with the draining pump <NUM> for draining the washing water in the sump <NUM> through the drainage flow path <NUM>. The draining pump <NUM> includes a draining motor (not shown) for generating a rotational force. When the draining pump <NUM> is operated, the washing water stored in the sump <NUM> flows to the outside of the case <NUM> through the drainage flow path <NUM>.

A filter <NUM> is installed in the communication hole 12c to filter the dirt from the washing water moving from the tub <NUM> to the sump <NUM>.

The washing pump <NUM> sends the washing water stored in the sump <NUM> to at least one of the plurality of spray arms <NUM>, <NUM> and <NUM>. The washing pump <NUM> is connected to the switching valve <NUM> and a washing water supply path <NUM>. When the washing pump <NUM> is operated, the washing water stored in the sump <NUM> flows into the washing pump <NUM> through a water collecting flow path <NUM> and is then sent to the switching valve <NUM> through the washing water supply flow path <NUM>. A check valve <NUM> is provided inside the water collecting flow path <NUM> or between the water collecting flow path <NUM> and the washing pump <NUM>.

The washing pump <NUM> is installed at one lateral side of the sump <NUM>. The washing pump <NUM> is connected to a steam hose <NUM>. The steam generated in the washing pump <NUM> is supplied to a steam nozzle <NUM> through the steam hose <NUM>.

The heater <NUM> is coupled to the lower side of the washing pump <NUM> to heat the washing water in the washing pump <NUM>. The heater <NUM> generates hot water by heating the washing water flowing in the washing pump <NUM> when the washing pump <NUM> operates. The heater <NUM> generates steam by heating the washing water existing inside the washing pump <NUM> while maintaining the level of the washing water existing inside the washing pump <NUM> at a certain level or higher. Accordingly, the heater <NUM> generates steam by heating the washing water existing inside the washing pump <NUM>, while intermittently operating the washing pump <NUM>, or the heater <NUM> generates steam by heating the washing water stored in the washing pump <NUM>, when the washing pump <NUM> is stopped.

The hot water generated by the heater <NUM> is sprayed into the tub <NUM> through at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>. The steam generated by the heater <NUM> flows along the steam hose <NUM> and is discharged into the tub <NUM> through the steam nozzle <NUM>.

The steam nozzle <NUM> is provided at the lower end of the door <NUM> to discharge the steam generated by the heater <NUM> to the washing chamber 12a. The steam discharged from the steam nozzle <NUM> is applied to the washing object accommodated in the lower rack <NUM> and/or the upper rack <NUM>.

The switching valve <NUM> selectively connects the sump <NUM> to at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>. The switching valve <NUM> selectively supplies the washing water sent by the washing pump <NUM> to at least one of the lower spray arm <NUM>, the upper spray arm <NUM>, and the top spray arm <NUM>. The switching valve <NUM> selectively connects the washing water supply flow path <NUM> and at least one of the plurality of spray arm connecting flow paths <NUM>, <NUM>, and <NUM>. The switching valve <NUM> is disposed in the sump <NUM>.

The check valve <NUM> is disposed between the sump <NUM> and the washing pump <NUM> and is opened in the direction of the washing pump <NUM> from the sump <NUM>. The check valve <NUM> is opened to allow the washing water to flow from the sump <NUM> to the washing pump <NUM> and is closed to allow the steam not to flow from the washing pump <NUM> to the sump <NUM>. The check valve <NUM> is opened by rotating the lower portion around the upper portion. The check valve <NUM> is disposed inside the water collecting flow path <NUM> or connected between the water collecting flow path <NUM> and the washing pump <NUM> to open and close the water collecting flow path <NUM>.

The check valve <NUM> is opened when the washing pump <NUM> operates to flow the washing water, and is closed when the washing pump <NUM> stops and the washing water does not flow. The check valve <NUM> is opened by the flow pressure of the washing water of the washing pump <NUM>. According to an embodiment, the check valve <NUM> may be a solenoid valve that is opened or closed by an electronic signal.

The check valve <NUM> is formed to allow the washing water to flow from the washing pump <NUM> to the sump <NUM> even when it is closed during operation of the draining pump <NUM>.

<FIG> is a perspective view of a washing pump according to an embodiment of the present invention, <FIG> is an exploded perspective view of a washing pump according to an embodiment of the present invention, <FIG> is an exploded perspective view of a heater according to an embodiment of the present invention, and <FIG> is a schematic cross-sectional view of a washing pump according to an embodiment of the present invention.

The washing pump <NUM> according to an embodiment of the present invention includes a cylindrical housing <NUM> which is coupled to the sump <NUM>, a washing water intake pipe <NUM> which is connected to the housing <NUM> and through which the washing water flows into the housing <NUM> by the rotation of an impeller <NUM>, a washing water outflow pipe <NUM> which is connected to the housing <NUM> and through which the washing water is discharged to the outside of the housing <NUM> by the rotation of the impeller <NUM>, an impeller <NUM> which is disposed inside the housing <NUM> and sends the washing water introduced into the washing water intake pipe <NUM> to the washing water outflow pipe <NUM>, a washing motor <NUM> which rotates the impeller <NUM>, a heater <NUM> which is coupled to the housing <NUM> and generates steam by heating the washing water inside the housing <NUM>, and a steam discharge pipe <NUM> which is disposed in the washing water outflow pipe <NUM> and discharges steam generated by the heater <NUM>.

The housing <NUM> is formed in a cylindrical shape having opened top and bottom surfaces. The housing <NUM> is coupled to the sump <NUM>. A housing cover <NUM> is coupled to the upper end of the housing <NUM>, and the heater <NUM> is coupled to the lower end thereof. The housing cover <NUM> covers the upper portion of the housing <NUM>, and the housing cover <NUM> is provided with the washing motor <NUM> for rotating the impeller <NUM> by generating a rotational force.

A partition wall <NUM> is disposed inside the housing <NUM>. The partition wall <NUM> is disposed at the middle end of the housing <NUM> to divide an internal space vertically. The partition wall <NUM> is disposed below the impeller <NUM>. The partition wall <NUM> is disposed above the washing water intake pipe <NUM> and disposed below the washing water outflow pipe <NUM>. The partition wall <NUM> forms a lower chamber C1 and an upper chamber C2 inside the housing <NUM>. The lower chamber C1 is the place where a negative pressure is generated by the rotation of the impeller <NUM> and the upper chamber C2 is the place where the impulse <NUM> is accommodated and a positive pressure is generated by the rotation of the impeller <NUM>. The lower chamber C1 is connected to the sump <NUM> through the water collecting flow path <NUM> and the washing water intake pipe <NUM>. The upper chamber C2 is connected to the switching valve <NUM> through the washing water outflow pipe <NUM> and the washing water supply flow path <NUM>. In addition, it is connected to the steam nozzle <NUM> through the steam discharge pipe <NUM> and the steam hose <NUM>.

The partition wall <NUM> divides the washing pump <NUM> into a pump lower portion <NUM> through which the washing water is introduced by the rotation of the impeller <NUM> and a pump upper portion <NUM> through which the washing water is discharged by the rotation of the impeller <NUM>. The washing water is introduced to the inside of the pump lower portion <NUM>, and the lower chamber C1 is formed in the inside of the pump lower portion <NUM>. The pump lower portion <NUM> includes a lower portion of the housing <NUM> and the washing water intake pipe <NUM>. The pump lower portion <NUM> may further include a heater cover <NUM> of the heater <NUM>.

The pump upper portion <NUM> discharges washing water or steam to the outside, and forms the upper chamber C2 therein. The pump upper portion <NUM> includes an upper portion of the housing <NUM>, the washing water outflow pipe <NUM>, the steam discharge pipe <NUM>, and the housing cover <NUM>. The impeller <NUM> is disposed inside the pump upper portion <NUM> and the washing motor <NUM> is disposed in the upper side of the pump upper portion <NUM>.

The partition wall <NUM> includes a partition hole <NUM> for communicating the lower chamber C1 and the upper chamber C2. The upper surface of the upper chamber C2 side of the partition wall <NUM> is formed in a volute shape so that the washing water introduced to the upper chamber C2 through the partition hole <NUM> from the lower chamber C1 is guided to the washing water outflow pipe <NUM>. A guider (not shown) protruding downward is formed on the lower surface of the lower chamber C1 side of the partition wall <NUM>. The guider of the partition wall <NUM> guides the washing water introduced into the lower chamber C1 through the washing water intake pipe <NUM> to the partition wall hole <NUM>. The guider of the partition wall <NUM> allows the washing water in the lower chamber C1 to be uniformly heated by the heater <NUM>.

The impeller <NUM> is rotated by the washing motor <NUM> and flows the washing water in the housing <NUM> to send to the outside. The impeller <NUM> is rotatably disposed in the upper chamber C2. The impeller <NUM> sends the washing water introduced into the upper chamber C2 from the lower chamber C1 through the partition hole <NUM> to the washing water outflow pipe <NUM>.

The washing water intake pipe <NUM> is connected to the lower chamber C1 side of the housing <NUM>. The washing water intake pipe <NUM> is connected to the water collecting flow path <NUM> to allow the washing water of the sump <NUM> to flow into the lower chamber C1. The washing water intake pipe <NUM> is disposed to protrude outward from the lower sidewall of the housing <NUM>. The washing water intake pipe <NUM> is disposed in such a manner that the pipe direction is horizontal, so that the washing water flows in the horizontal direction.

The washing water outflow pipe <NUM> is connected to the upper chamber C2 side of the housing <NUM>. The washing water outflow pipe <NUM> is connected to the washing water supply flow path <NUM> so that the washing water in the upper chamber C2 is discharged to the washing water supply flow path <NUM>. The washing water outflow pipe <NUM> is disposed to protrude outward from the upper side wall of the housing <NUM>. The washing water outflow pipe <NUM> is horizontally disposed so that the washing water flows in a horizontal direction.

The steam discharge pipe <NUM> is connected to the upper chamber C2 side of the housing <NUM>. The steam discharge pipe <NUM> is disposed above the partition wall <NUM>. The steam discharge pipe <NUM> may be disposed at various positions of the housing <NUM> so as to connect the upper chamber C2 of the housing <NUM> and the steam hose <NUM>. In the present embodiment, the steam discharge pipe <NUM> is disposed in the washing water outflow pipe <NUM>. The steam discharge pipe <NUM> is disposed to be inclined so that the steam discharge direction is inclined upward. The steam discharge direction of the steam discharge pipe <NUM> is perpendicular to the washing water discharge direction of the washing water outflow pipe <NUM>.

The steam discharge pipe <NUM> is connected to the steam hose <NUM> and discharges the steam generated in the housing <NUM> by the heater <NUM> to the steam hose <NUM>. The steam hose <NUM> is connected to the upper chamber C2 through the steam discharge pipe <NUM>.

The heater <NUM> is connected to the lower end of the housing <NUM> to form a bottom surface of the housing <NUM>. The heater <NUM> heats the washing water flowing inside the housing <NUM> when the impeller <NUM> rotates. The heater <NUM> generates steam by heating the washing water stored inside the housing <NUM>. The heater <NUM> is disposed below the washing water intake pipe <NUM>. The heater <NUM> is disposed below the partition wall <NUM>. A part of the heater <NUM> is disposed inside the housing <NUM>.

The check valve <NUM> is coupled to the washing water intake pipe <NUM>. The upper end of the check valve <NUM> is coupled to the upper end of the washing water intake pipe <NUM>. The check valve <NUM> is opened when the impeller <NUM> rotates and is closed when the impeller <NUM> does not rotate. The check valve <NUM> is opened when the washing motor <NUM> is operated and closed when the washing motor <NUM> is stopped. The check valve <NUM> is closed when the heater <NUM> generates steam so that the steam generated inside the housing <NUM> is prevented from flowing out to the sump <NUM> through the lower chamber C1 and the washing water intake pipe <NUM>. However, when steam is generated while the impeller <NUM> rotates, the check valve <NUM> may be opened such that the level of the washing water existing inside the housing <NUM> is maintained at a certain level or higher.

The check valve <NUM> is configured to allow the washing water to flow from the washing pump <NUM> to the sump <NUM> during operation of the draining pump <NUM>. The check valve <NUM> is formed in such a manner that a part of the lower portion of the washing water intake pipe <NUM> is opened when it is closed. The check valve <NUM> is formed to block <NUM>% to <NUM>% of the cross-sectional area of the washing water intake pipe <NUM> when it is closed, and is preferably formed to cover <NUM>% of the cross-sectional area of the washing water intake pipe <NUM>.

The check valve <NUM> may be closed to prevent the washing water and the steam from flowing from the washing pump <NUM> to the sump <NUM> during the steam generation of the heater <NUM>. However, when steam is generated, while the impeller <NUM> rotates, the check valve <NUM> may be opened such that the level of the washing water existing in the housing <NUM> is maintained at a certain level or higher. When the draining pump <NUM> and the motor <NUM> are stopped (when not operating), the check valve <NUM> may store the washing water inside the housing <NUM>. The heater <NUM> heats the washing water stored inside the housing <NUM> by the check valve <NUM> and generates steam.

The heater <NUM> according to an embodiment of the present invention includes a heater cover <NUM> which forms a bottom surface of the housing <NUM>, a heating element <NUM> which is joined to the lower side of the heater cover <NUM> and heats the heater cover <NUM>, a heater plate <NUM> which is joined to the lower side of the heating element <NUM> and the heater cover <NUM> and transfers the heat of the heating element <NUM> to the heater cover <NUM>, a thermostat <NUM> which supplies power to the heating element <NUM> and adjusts the temperature of the heating element <NUM>, a wire <NUM> which electrically connects the heating element <NUM> and the thermostat <NUM>, and a heater shield <NUM> which covers a part of the heater plate <NUM> from the lower side.

The heater cover <NUM> is coupled to the lower end of the housing <NUM> and forms the bottom surface of the housing <NUM> of the washing pump <NUM>. The upper surface of the heater cover <NUM> is in contact with the washing water. The heating element <NUM> and the heater plate <NUM> are joined to the lower side of the heater cover <NUM>. The heater cover <NUM> is heated by the heating element <NUM> and the heater plate <NUM> to heat the washing water.

The circumference of the heater cover <NUM> is formed in a circular shape, and a plurality of bends in a vertical direction are formed at the position of concentric circle. The heater cover <NUM> is partly annularly protruded upward (toward the partition wall <NUM> side of the washing pump <NUM>). A part of the heater cover <NUM> protrudes inward of the housing <NUM> to form an annular space in which a part of the heating element <NUM> is accommodated. A part of the heater cover <NUM> is disposed between the washing water accommodated in the housing <NUM> and the heating element <NUM>. Thus, the heating element <NUM> is not in contact with the washing water accommodated in the housing <NUM>.

The heater cover <NUM> includes a cover base <NUM> having a disk shape, a cover holder <NUM> protruding upward from the circumference of the cover base <NUM>, and a cover rim <NUM> which is formed around the cover holder <NUM> and is coupled with the housing <NUM>.

The cover base <NUM> is formed of a circular plate and forms a central portion of the heater cover <NUM>. The central portion of the heater plate <NUM> is joined to the lower side of the cover base <NUM>. The cover base <NUM> and the central portion of the heater plate <NUM> are joined by brazing.

The cover holder <NUM> is formed in a ring shape protruding upward. The cover holder <NUM> forms an annular space in which a part of the heating element <NUM> is accommodated. In the annular space of the cover holder <NUM>, a heating main body <NUM> of heating element <NUM> described later is accommodated. A part of the heating element <NUM> is joined to the inside of the cover holder <NUM>. The cover holder <NUM> and a part of the heating element <NUM> are joined by brazing.

The longitudinal section from the center to the radial direction of the cover holder <NUM> is formed in an open curve whose lower side is open. At least part of the cover holder <NUM> is formed to correspond to a part of the shape of the heating element <NUM> accommodated in the annular space of the cover holder <NUM>. The cover holder <NUM> accommodates a part of the heating element <NUM> and is in direct contact with a part of the heating element <NUM>. The inner surface of the outer circumference of the cover holder <NUM> is spaced apart from the outer circumferential surface of a part of the heating element <NUM> accommodated in the annular space of the cover holder <NUM>.

The cover rim <NUM> is formed in a rim shape. The cover rim <NUM> is formed to surround the lower end of the housing <NUM>. The circumferential end of the cover rim <NUM> protrudes upward and is coupled with the housing <NUM>. Since the cover rim <NUM> is not in contact with the heater plate <NUM> and the heating element <NUM>, it is heated to a relatively low temperature.

The heating element <NUM> receives power from the thermostat <NUM> through a wire <NUM> and generates heat. The heating element <NUM> heats the heater cover <NUM> and the heater plate <NUM>. The heater cover <NUM> is joined to the upper side of the heating element <NUM> by brazing, and the heater plate <NUM> is joined to the lower side thereof by brazing.

The outer circumference of a part of the heating element <NUM> is spaced apart from the portion of the heater cover <NUM> forming an annular space. A part of the heating element <NUM> is accommodated in the annular space formed in the heater cover <NUM> and disposed inside the housing <NUM>. The heating element <NUM> is disposed below the heater cover <NUM> forming the bottom surface of the housing <NUM> and disposed in the outside of the washing pump <NUM> but partially disposed in the inside of the housing <NUM>.

The heating element <NUM> includes an arc-shaped heating main body <NUM> for generating heat and a heating terminal <NUM> for supplying power to the heating main body <NUM>.

The heating main body <NUM> is formed in an arc shape whose center angle is larger than <NUM> degrees. The heating main body <NUM> is accommodated inside the cover holder <NUM>. The upper surface and the inner circumferential surface of the heating main body <NUM> come into contact with the heater cover <NUM> to heat the heater cover <NUM>. The lower surface and the outer circumferential surface of the heating main body <NUM> are brought into contact with the heater plate <NUM> to heat the heater plate <NUM>. The heating main body <NUM> is disposed higher than the lower end of the housing <NUM>.

The heating terminal <NUM> receives power from the thermostat <NUM> through the wire <NUM> and transfers the power to the heating main body <NUM>. A plurality of heating terminals <NUM> are provided at both ends of the heating main body <NUM>. The plurality of heating terminals <NUM> are extended from both ends of the heating main body <NUM> and formed to be inclined downward. That is, the plurality of heating terminals <NUM> are formed to protrude downward from a plane formed by the lower end of the heating main body <NUM>.

The heater plate <NUM> is heated by the heating element <NUM> to heat the cover base <NUM> of the heater cover <NUM>. The heater plate <NUM> uniformly distributes the heat of the heating element <NUM> to uniformly heat the heater cover <NUM>. The heater plate <NUM> is formed in a bowl shape. The circumferential inner surface of the heater plate <NUM> is in contact with the heating element <NUM>, but the circumferential outer surface thereof is spaced apart from the heater cover <NUM>. A heater shield <NUM> is disposed below the heater plate <NUM>.

<FIG> is a block diagram of a dishwasher according to an embodiment of the present invention, and <FIG> is a view showing each process in a method of controlling a dishwasher according to an embodiment of the present invention.

A controller <NUM> receives the flow rate of the washing water measured by the flow meter <NUM>, and controls the water supply valve <NUM>, the washing motor <NUM> of the washing pump <NUM>, the heater <NUM>, the draining pump <NUM>, and the switching valve <NUM> to perform washing for the washing object. The controller <NUM> performs each process according to the washing course selected by a user.

In the present embodiment, the controller <NUM> sequentially performs a preliminary washing <NUM> P310, a preliminary washing <NUM> P320, a preliminary washing <NUM> P330, a steam washing P340, a main washing P350, a rinsing P360, and a heat rinsing P370.

A plurality of preliminary washings P310, P320, P330 are a process for spraying washing water on the washing object to remove dirt attached to the washing object. In each of the plurality of preliminary washings P310, P320, P330, the controller <NUM> controls the water supply valve <NUM> to supply the washing water from the external water source into the sump <NUM>. After the water supply, the controller <NUM> operates the washing pump <NUM> to send the washing water in the sump <NUM> and controls the switching valve to spray the washing water through at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>. The washing water sprayed through at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM> drops the dirt attached to the washing object onto the bottom 12b of the tub <NUM> and collects it in the filter <NUM>. After spraying the washing water, the controller <NUM> operates the draining pump <NUM> to drain the washing water in the sump <NUM> to the outside.

In the present embodiment, it is illustrated that the preliminary washing P310, P320, P330 is performed three times, but may be performed at least once, i.e., various number of times, according to the embodiment.

The steam washing P340 is a process in which heated washing water is sprayed on a washing object and steam is applied to the washing object to sterilize and to soak the washing object. Details of the steam washing P340 will be described later with reference to <FIG>.

The main washing P350 is a process of heating the washing object by spraying the heated washing water onto the washing object and removing the dirt attached to the washing object. During the main washing P350, the controller <NUM> controls the water supply valve <NUM> to supply the washing water from the external water source to the sump <NUM>, and then controls the heater <NUM> to heat the washing water, operates the washing pump <NUM> to spray the heated washing water through at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>, and then operates the draining pump <NUM> to drain the washing water in the sump <NUM> to the outside. During the main washing P350, the washing detergent may be mixed with the washing water.

The rinsing P360 is a process for removing residual dirt attached to the washing object. In the rinsing P360, the controller <NUM> controls the water supply valve <NUM> to supply the washing water from the external water source to the sump <NUM>, and then operates the washing pump <NUM> to spray the washing water through at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>, and then operates the draining pump <NUM> to drain the washing water in the sump <NUM> to the outside. During the rinsing P360, the rinsing detergent may be mixed with the washing water.

The heat rinsing P370 is a process for heating the washing object by spraying heated washing water onto the washing object. In the heat rinsing P370, the controller <NUM> controls the water supply valve <NUM> to supply the washing water from the external water source to the sump <NUM>, and then controls the heater <NUM> to heat the washing water, operates the washing pump <NUM> to spray the heated washing water through at least one of the plurality of spray arms <NUM>, <NUM>, and <NUM>, and then operates the draining pump <NUM> to drain the washing water in the sump <NUM> to the outside.

According to the embodiment, the steam washing P340 may be performed between the main washing P350 and the rinsing P360, between the rinsing P360 and the heat rinsing P370, or after the heat rinsing P370.

<FIG> is a flowchart showing a method of controlling a dishwasher according to an embodiment of the present invention, <FIG> is a view showing the state of a washing pump after completion of sump washing in a method of controlling a dishwasher according to an embodiment of the present invention, <FIG> is a view showing the state of a washing pump during hot water circulation in a method of controlling a dishwasher according to an embodiment of the present invention, <FIG> is a view showing the state of a washing pump when starting a steam generation in a method of controlling a dishwasher according to an embodiment of the present invention, and <FIG> is a view showing the state of a washing pump when a steam generation is completed in a method of controlling a dishwasher according to an embodiment of the present invention.

The controller <NUM> performs a preliminary washing draining P339 at a final step of the preliminary washing <NUM> P330. In the preliminary washing draining P339, the controller <NUM> operates the draining pump <NUM> to drain the washing water stored in the sump <NUM> to the outside. When the controller <NUM> operates the draining pump <NUM>, the washing water stored in the sump <NUM> is discharged to the outside of the case <NUM> through the drainage flow path <NUM>.

When all of the washing water stored in the sump <NUM> is drained, the controller <NUM> stops the draining pump <NUM> and performs the steam washing P340.

The controller <NUM> performs a water supply for sump washing P341 of the steam washing P340. In the water supply for sump washing P341, the controller <NUM> opens the water supply valve <NUM> to supply the washing water from the external water source to the sump <NUM>. When the controller <NUM> opens the water supply valve <NUM>, the washing water supplied from the external water source flows into the sump <NUM> through the water supply flow path <NUM>. The controller <NUM> closes the water supply valve <NUM> when it is determined that a proper amount of washing water is supplied to the sump <NUM> at the flow rate of the washing water measured by the flow meter <NUM>.

When the water supply for sump washing P341 is completed, the controller <NUM> performs a draining for sump washing P342. In the draining for sump washing P342, the controller <NUM> operates the draining pump <NUM> to drain the washing water supplied to the sump <NUM> to the outside through the drainage flow path <NUM>. At this time, the dirt in the sump <NUM> is discharged to the outside through the drainage flow path <NUM> along with the washing water. The controller <NUM> stops the draining pump <NUM> when sensing that all the washing water in the sump <NUM> has been drained through the draining motor of the draining pump <NUM>.

During the draining for sump washing P342, the washing water inside the housing <NUM> of the washing pump <NUM> flows to the sump <NUM> through a gap between the lower end of the check valve <NUM> and the lower portion of the washing water intake pipe <NUM> and then discharged to the outside through the drainage flow path <NUM>. Accordingly, as shown in <FIG>, when the draining for sump washing P342 is completed, no washing water or very little washing water is stored inside the housing <NUM> of the washing pump <NUM>. When the draining for sump washing P342 is completed, the water level of the washing water inside the housing <NUM> of the washing pump <NUM> is lower than the upper end of the heater <NUM>.

The controller <NUM> does not operate the washing motor <NUM> of the washing pump <NUM> and the heater <NUM> from the start of the water supply for sump washing P341 to the completion of the draining for sump washing P342. The water supply for sump washing P341 and the draining for sump washing P342 are steps for removing dirt inside the sump <NUM> (and the washing pump <NUM>), and remove dirt in the sump <NUM> by supplying the washing water to the sump <NUM>, and then draining the washing water intactly.

When the draining for sump washing P342 is completed, the controller <NUM> performs a water supply for steam P343. During the water supply for steam P343, the controller <NUM> opens the water supply valve <NUM> to supply the washing water from the external water source to the sump <NUM>. When the controller <NUM> opens the water supply valve <NUM>, the washing water supplied from the external water source flows into the sump <NUM> through the water supply flow path <NUM>. The controller <NUM> closes the water supply valve <NUM> when it is determined that a proper amount of washing water has been supplied to the sump <NUM> at the flow rate of the washing water measured by the flow meter <NUM>.

During the water supply for steam P343, it is preferable that the water level of the washing water supplied to the sump <NUM> is lower than the water level of the washing water supplied to the sump <NUM> during the water supply of the plurality of preliminary washings P310, P320 and P330, the main washing P350, the rinsing P360, and the heat rinsing P370. In addition, it is preferable that the water level of the washing water is supplied to the sump <NUM> during the water supply for steam P343 is lower than the water level of the washing water supplied to the sump <NUM> during the water supply for sump washing P341. The amount of the washing water supplied to the sump <NUM> during the water supply for steam P343 is satisfactory as long as the washing water supplied to the sump <NUM> fills the housing <NUM> of the washing pump <NUM>. In the amount of the washing water supplied to the sump <NUM> during the water supply for steam P343, it is preferable that the water level is lower than the lowermost end of the steam discharge pipe <NUM> when the washing water flows into the housing <NUM> of the washing pump <NUM>.

As shown in <FIG>, even if the water supply for steam P343 is completed, no washing water or very little washing water is stored inside the housing <NUM> of the washing pump <NUM>. Since the check valve <NUM> is closed during the water supply for steam P343, the water level of the washing water inside the housing <NUM> of the washing pump <NUM> is lower than the upper end of the heater <NUM> when the draining for sump washing P342 is completed.

When the water supply for steam P343 is completed, the controller <NUM> controls the switching valve <NUM> to connect the washing pump <NUM> to all of the plurality of spray arms <NUM>, <NUM>, and <NUM> (P344). The controller <NUM> controls the switching valve <NUM> so that the washing water supply path <NUM> is connected to all of the plurality of spray arm connecting flow paths <NUM>, <NUM>, and <NUM>.

When the control of the switching valve <NUM> of the controller <NUM> is completed, the controller <NUM> operates the heater <NUM> and the washing motor <NUM> to circulate the hot water (P345). The controller <NUM> operates the heater <NUM> to heat the washing water flowing in the housing <NUM> of the washing pump <NUM>, and operates the washing motor <NUM> to send the heated washing water to all of the plurality of spray arms <NUM>, <NUM>, and <NUM>. The controller <NUM> simultaneously operates the heater <NUM> and the washing pump <NUM> to spray the heated washing water through all of the plurality of spray arms <NUM>, <NUM>, and <NUM>. The heated washing water sprayed through all of the plurality of spray arms <NUM>, <NUM> and <NUM> is applied to the washing object and then flows to the bottom 12b of the tub <NUM> and is collected in the sump <NUM>. The washing water collected in the sump <NUM> flows to the washing pump <NUM> and is heated and sent.

Referring to <FIG>, when the controller <NUM> operates the washing motor <NUM>, the check valve <NUM> is opened so that the washing water stored in the sump <NUM> is filled in the housing <NUM> through the water collecting flow path <NUM> and the washing water intake pipe <NUM>, and then sent to the plurality of spray arms <NUM>, <NUM> and <NUM> through the washing water outflow pipe <NUM>.

The controller <NUM> stops the heater <NUM> and the washing motor <NUM> when a set time is elapsed, thereby completing a hot water circulation (P346). Referring to <FIG>, when the controller <NUM> stops the washing motor <NUM>, the check valve <NUM> is closed so that the heated washing water is stored in the housing <NUM>. The water level of the washing water stored in the housing <NUM> is higher than the uppermost end of the heater <NUM> and lower than the lowermost end of the steam discharge pipe <NUM>.

The above described hot water circulation through the operation of the heater <NUM> and the washing motor <NUM> may be omitted depending on an embodiment.

When the hot water circulation is completed, the controller <NUM> controls the switching valve <NUM> so that the washing pump <NUM> is connected to the top spray arm <NUM> which is a spray arm disposed at the uppermost end among the plurality of spray arms <NUM>, <NUM> and <NUM> (P347). The controller <NUM> controls the switching valve <NUM> so that the washing water supply path <NUM> is connected to the top spray arm connecting flow path <NUM>.

When the control of the switching valve <NUM> of the controller <NUM> is completed, the controller <NUM> operates the heater <NUM> to generate steam (P348). The controller <NUM> operates the heater <NUM> to generate steam while maintaining the washing water in the housing <NUM> at a certain level or higher.

In a steam generation method according to an <NUM>. p example not forming part of the claimed scope of protection, the controller <NUM> operates only the heater <NUM> while the washing motor <NUM> is stopped and heats the washing water stored in the housing <NUM> of the washing pump <NUM>. The certain level in the present embodiment may be based on the upper end of the heating element <NUM> of the heater <NUM>. Accordingly, the controller <NUM> can generate steam by operating the heater <NUM> while maintaining the water level higher than the upper end of the heating element <NUM> of the heater <NUM> in a state where the washing motor <NUM> is stopped.

When the heater <NUM> heats the washing water that is not flowing in the housing <NUM> to a high temperature, steam is generated inside the housing <NUM>. Since the washing water in the housing <NUM> should be vaporized when steam is generated, the controller <NUM> does not operate the washing motor <NUM> and maintains a stopped state. The steam generated inside the housing <NUM> flows to the steam nozzle <NUM> through the steam discharge pipe <NUM> and the steam hose <NUM>. The steam discharged from the steam nozzle <NUM> is applied to the washing object.

Referring to <FIG>, since the washing motor <NUM> is stopped in this example when steam is generated, the check valve <NUM> is closed so that the washing water heated during the hot water circulation is stored in the housing <NUM>. The heater <NUM> heats the heated washing water stored in the housing <NUM> to generate steam.

Most of the steam generated inside the housing <NUM> of the washing pump <NUM> flows into the steam hose <NUM> through the steam discharge pipe <NUM> without flowing into the washing water supply path <NUM> through the washing water outflow pipe <NUM>. Since the cross sectional area of the flow path of the washing pump <NUM> connected to the top spray arm <NUM> is smaller than the cross sectional area of the flow path connected to the other spray arm, and the height of the flow path of the washing pump <NUM> connected to the top spray arm <NUM> is higher than height of the flow path connected to the other spray arm, most of the steam generated in the housing <NUM> flows to the steam hose <NUM> through the steam discharge pipe <NUM> in a state where the switching valve <NUM> connects the washing pump <NUM> to the top spray arm <NUM>.

In the above-described steam generation, the controller <NUM> operates the heater <NUM> at a temperature higher than the hot water circulation P345. That is, the temperature at which the heater <NUM> heats the washing water during the steam generation is higher than the temperature at which the heater <NUM> heats the washing water during the hot water circulation P345. The controller <NUM> operates the heater <NUM> at a temperature of <NUM> degrees Celsius or more, and it is preferable that the actual washing water is heated to <NUM> degrees Celsius.

The controller <NUM> stops the heater <NUM> to complete the steam generation when a set time is elapsed (P349). It is preferable that the controller <NUM> makes the execution time of the steam generation P348 in which only the heater <NUM> is operated to be longer than the execution time of the hot water circulation P348 in which the heater <NUM> and the washing motor <NUM> are simultaneously operated.

The controller <NUM> performs the hot water circulation P348 such that the washing water stored in the sump <NUM> passes through the check valve <NUM> and is sufficiently introduced into the housing <NUM> of the washing pump <NUM> to be stored therein. The controller <NUM> performs steam generation P348 so that the water level of the washing water inside the housing <NUM> which is lowered by the steam generation is not lowered than the upper end of the heating element <NUM> of the heater <NUM>.

Referring to <FIG>, when the steam generation is completed, the water level of the washing water inside the housing <NUM> is lowered. Since the amount of steam supplied into the tub <NUM> during the steam generation is limited to the amount of washing water that can be stored inside the housing <NUM>, it is necessary to supply the washing water to the inside of the housing <NUM> again after the steam generation so as to supply more steam into the tub <NUM>.

After completing the steam generation, the controller <NUM> controls the switching valve <NUM> to connect the washing pump <NUM> to all of the plurality of spray arms <NUM>, <NUM> and <NUM> (P344) and to operate the heater <NUM> and the washing motor <NUM> (P345) to perform the hot water circulation again. In addition, the controller <NUM> stops the heater <NUM> and the washing motor <NUM> (P346) to complete a second hot water circulation, and then controls the switching valve <NUM> so that the washing pump <NUM> is connected to the top spray arm <NUM> and the heater <NUM> is operated (P348) to perform the steam generation again.

In the steam generation method according to the present invention, the controller <NUM> operates the heater <NUM> while operating the washing motor <NUM> to heat the washing water stored inside the housing <NUM> of the washing pump <NUM>. The certain water level in the present embodiment may be formed higher than the upper end of the heating element <NUM> of the heater <NUM>. However, in the present embodiment, the certain water level may be formed lower than the water level of the state where the heated washing water is stored in the housing <NUM> as the washing motor <NUM> is stopped and the check valve <NUM> is closed, in a state where the hot water circulation is completed.

The heater <NUM> heats the washing water to a high temperature while the water level inside the housing <NUM> is maintained at a certain level, so that steam is generated inside the housing <NUM>. According to the present invention, a part of the washing water inside the housing <NUM> may flow, but the flow thereof may be slight so that the washing water inside the housing <NUM> is vaporized. The impeller <NUM> is rotated so that the washing water having the above-mentioned level flows, and both the steam and the heated washing water may be discharged to the steam nozzle <NUM> due to the rotation of the impeller <NUM>.

In the steam generation method according to the present invention, since the impeller <NUM> is rotated, the water level of the washing water existing inside the housing <NUM> can be maintained at a certain level or higher. Therefore, unlike the case of generating steam while stopping the impeller <NUM>, according to the example described above, the water level of the washing water existing inside the housing <NUM> can be maintained to some extent. This is advantageous in that it is not necessary to repeat the hot water circulation (P348) process for supplying the washing water into the housing <NUM> in order to maintain the water level of the washing water inside the housing <NUM> at a certain level or higher.

After completing the steam generation, the controller <NUM> operates the draining pump <NUM> to drain the washing water stored in the sump <NUM> to the outside and performs the main washing (P350).

After completing the steam generation, the controller <NUM> does not drain and controls the water supply valve <NUM> to additionally supply the washing water from the external water source to the sump <NUM>, and then may perform the main washing (P350). In this case, the hot water generated during the steam generation can be used, thereby saving the energy used for the heater <NUM>.

According to the dish washer of the present invention and the controlling method therefor, one or more of the following effects can be obtained.

First, as the steam is generated from the pump after the sump is washed, the decrease of steam generation due to the dirt and the pump failure can be prevented.

Second, the steam is smoothly discharged while reducing the waste of energy and generating the steam quickly, by controlling the amount of washing water that is supplied during water supply before the steam is generated.

Third, the washing water stored in the sump is transferred to the pump by circulating washing water before steam generation.

Fourth, the steam is generated quickly by preheating the washing water when the washing water is circulated before steam generation.

Fifth, the water level of the washing water existing inside the washing pump is maintained at a certain level or higher to prevent the overheat of the heater due to lack of washing water.

Sixth, the loss of steam through the washing water circulating flow path can be minimized by connecting the washing pump to the spray arm disposed in the uppermost end during steam generation.

Claim 1:
A method of controlling a dishwasher (<NUM>) comprising a tub, a plurality of spray arms (<NUM>, <NUM>, <NUM>) for spraying washing water into the tub, a steam nozzle (<NUM>) for spraying steam into the tub, a sump (<NUM>) for storing the washing water, and a washing pump (<NUM>) for sending the washing water stored in the sump (<NUM>) to the tub by the rotation of an impeller (<NUM>) and heating the washing water contained therein, the method comprising:
a preliminary washing step including: <NUM>) supplying washing water to the sump (<NUM>) from an external water source, <NUM>) operating the washing pump (<NUM>) so that washing water in the sump (<NUM>) is sprayed through at least one of the plurality of spray arms (<NUM>, <NUM>, <NUM>), and <NUM>) operating a draining pump (<NUM>) to drain the washing water in the sump (<NUM>) to the outside;
a sump washing step of supplying the washing water to the sump (<NUM>) from the external water source before a subsequent steam supply step and then draining the washing water supplied to the sump (<NUM>);
a water supply for steam step of supplying washing water to the sump (<NUM>) from the external water source;
operating a washing motor (<NUM>) to rotate the impeller (<NUM>) so that the washing water supplied to the sump (<NUM>) flows to the washing pump (<NUM>); the method being characterized by
a steam generation step of maintaining a water level of the washing water existing inside the washing pump (<NUM>) at a certain water level or higher and heating the washing water by operating the washing motor (<NUM>) to rotate the impeller (<NUM>) and a heater (<NUM>) included in the washing pump (<NUM>).