Washing machine and control method thereof

Abstract

Disclosed herein are a washing machine having a plurality of washtubs and a control method thereof. In the washing machine having a plurality of washtubs, if it is determined that a washtub that is not in operation is present, dozens of liters of water used in a washtub that is in operation are moved into and stored in the non-operating washtub rather than being discharged to the outside. The moved water may be utilized in a following washing or rinsing stage of the washtub, or a washing or rinsing stage of the other washtub.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Application No. 10-2009-41234, filed May 12, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

This application generally relates to a washing machine that is capable of recycling rinse water.

2. Description of the Related Art

Generally, a washing machine (i.e. a conventional drum washing machine) includes a single washtub, in which dirty laundry is washed using water and detergent. To wash laundry, the washing machine performs a series of operations, such as a washing stage, rinsing stage, dehydrating stage, etc.

With respect to laundry washing, it may often be impossible to wash all laundry in a single washtub due to differences in the type or quality thereof. Thus, in the case of a washing machine having a single washtub, a user may need to sort different clothing that is difficult to wash together, to wash the clothing separately. This causes inconvenience due to separate washing and forces the user to operate the washing machine several times (e.g., two times), resulting in a serious waste of time and energy. In addition, if a large-capacity washtub is used to wash only a small quantity of laundry, operating the large-capacity washtub causes unnecessary power consumption.

The entire washing operation of a washing machine is divided into a washing stage, rinsing stage, and dehydrating stage, and causes consumption of considerable water because wash water used in the rising stage is directly discharged to the outside rather than being recycled. Moreover, the rinsing stage may be carried out at least three times and in the extreme case, five or six times based on the quantity of laundry or the user's selection, causing an increase in the consumption of water. In particular, disposing water used in the last one of several rinsing strokes without recycling despite the water being relatively clean may problematically increase the usage of water in a washing machine.

Recently, a drying function has been added to a washing machine, allowing the washing machine to perform even a drying stroke in which dehydrated laundry is dried. The washing machine having the drying function includes a drying device, which blows hot air generated by a drying heater into a space, in which laundry is received, so as to dry the laundry. This kind of washing machine may perform the drying function independently using the drying device, or may perform the drying function after completion of a dehydrating stage in association with a washing function.

If the drying stroke begins, a blowing fan is operated and the drying heater is turned on, causing hot air from the drying heater to be blown into a rotating tub in which laundry is received. Thereby, the laundry in the rotating tub is dried as the laundry repeatedly rises and falls due to rotation of the tub. The high-temperature air blown into the rotating tub is changed into wet vapor containing moisture absorbed from the laundry, and the resulting wet vapor is directed along a wall surface of a washtub toward the blowing fan. In this case, as cold water is ejected from a condensing hose connected to an external water source to the wall surface of the washtub, the moisture contained in the wet vapor to be suctioned to the blowing fan after being circulated in the rotating tub is condensed on the wall surface of the washtub and moves down. A small quantity of condensed water collected at the bottom of the rotating tub is discharged to the outside through a discharge hole.

Drying laundry as described above may require supply of water from an external source, and the supplied water is directly disposed of without recycling despite the water being relatively clean, resulting in increase in the usage of water in a washing machine.

SUMMARY

Therefore, it is an aspect of the present invention to provide a washing machine having a plurality of washtubs and a control method thereof, which may reduce the quantity of water used in the washing machine to the maximum extent.

Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

The foregoing and/or other aspects of the present invention are achieved by providing a control method of a washing machine having a plurality of washtubs, the method including determining whether or not a washtub that is in operation is present, and if the presence of the washtub that is in operation is determined, moving water used in the washtub that is in operation to a washtub that is not in operation.

The determination of the presence of the washtub that is in operation may include determining whether or not a washtub that is performing any one of a washing stage, rinsing stage, dehydrating stage, and drying stage is present.

The determination of the presence of the washtub that is in operation may include determining whether or not a washtub that is in a last rinsing stage is present.

The determination of the presence of the washtub that is in operation may include determining whether or not a washtub that is in the drying stage is present.

The control method may further include sensing the level of water generated in the drying stage of the washtub that is in operation, and moving the water generated in the drying stage to the washtub that is not in operation if the sensed level of water is a preset value or more.

The control method may further include storing the water moved into the washtub that is not in operation until the washtub that is in operation is stopped.

The water, moved into the washtub that is not in operation, may be returned when the washtub that is in operation performs any one of a following washing stroke and rinsing stroke.

The foregoing and/or other aspects of the present invention are achieved by providing a control method of a washing machine having a plurality of washtubs, the method including determining whether or not a washtub that is in operation is present, if the presence of the washtub that is in operation is determined, determining whether or not movement of water used in the operation is needed, and if movement of the water used in the operation is needed, moving the water used in the operation to a washtub that is not in operation.

The determination as to whether movement of the water used in the operation is needed may include determining whether or not the washtub that is in operation completes a last rinsing stage, and determining whether or not the level of water generated in a drying stage reaches a preset value.

The foregoing and/or other aspects of the present invention are achieved by providing a washing machine including a plurality of washtubs including a washtub that is in operation and an additional washtub, a water moving device to move water between the plurality of washtubs, and a controller to control the water moving device to move the water used in a washtub that is in operation to an additional washtub.

The controller may move water used in a washtub that is in a last rinsing stage or in a drying stage into a washtub that is not in operation.

The controller may move water used in a washtub that is performing any one of a washing stage, rinsing stage, dehydrating stage, and drying stage to a washtub that is not in operation.

The water moved into the additional washtub may be stored under control of the controller until the washtub that is in operation is stopped.

The controller may return the water moved into the additional washtub when the washtub that is in operation performs any one of a following washing stage and rinsing stage.

The water moving device may include at least one connecting pipe connecting two washtubs to each other, and an opening/closing valve and pump provided at the connecting pipe.

The connecting pipe may have one end connected to at least one of a drainpipe and condensing duct of a first washtub, and the other end connected to at least one of a drainpipe and condensing duct of a second washtub.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a perspective view illustrating an external appearance of a washing machine according to an exemplary embodiment of the present invention;

FIG. 2 is a sectional view illustrating an interior configuration of the washing machine according to the embodiment of FIG. 1;

FIG. 3 is a schematic control block diagram of the washing machine according to the embodiment of FIG. 1;

FIG. 4 is a flow chart illustrating a control operation of the washing machine according to the embodiment of FIG. 1;

FIG. 5 is a view illustrating movement of rinse water used in the last rinsing stroke in the case where a first washtub is not in operation and a second washtub is in the last rinsing stroke in the washing machine according to the embodiment of FIG. 1;

FIG. 6 is a view illustrating a state wherein the rinse water used in the last rinsing stroke is stored in the second washtub in the washing machine according to the embodiment of FIG. 1;

FIG. 7 is a flow chart illustrating a control operation of a washing machine according to a second embodiment of the present invention;

FIG. 8 is a view illustrating movement of water generated in a drying stroke in the case where the first washtub is not in operation and the second washtub is in the drying stroke in the washing machine according to the second embodiment of the present invention;

FIG. 9 is a view illustrating a state wherein the water generated in the drying stroke is stored in the second washtub in the washing machine according to the second embodiment of the present invention; and

FIG. 10 is a flow chart illustrating an operation of moving water stored in one washtub into the other washtub to be newly operated in a washing machine according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.

FIG. 1 illustrates an external appearance of a washing machine according to an exemplary embodiment of the present invention.

As shown in FIG. 1, the washing machine according to the embodiment of the present invention includes a body 10 defining an external appearance of the washing machine, and a plurality of doors (e.g. two doors) 11 and 12 provided at upper and lower parts of the body 10 for input of laundry. An input unit 400 to allow a user to input commands related to washing courses and operations of the washing machine and a display unit 410 to display the washing courses and operations of the washing machine are arranged between the plurality of doors 11 and 12.

The input unit 400 includes a power button, an operating/stoppage button to begin an operation of the washing machine, a washtub selecting button to allow the user to perform, e.g., simultaneous washing/drying operations or independent washing/drying operations using at least a selected one of a plurality of washtubs (e.g. two washtubs) that are provided to enable sorted washing of laundry, and other course and function buttons used to select a washing course and washing function of each washtub. Of course, the form of the input unit 400 is not limited to that shown, and various other forms may also be possible.

Detergent supply units 21 and 22 to supply detergent into the plurality of washtubs are provided respectively at the left upper end and center of the body 10.

Although the embodiment of FIG. 1 illustrates the detergent supply units 21 and 22 to supply detergent into the plurality of washtubs, respectively, it may also be possible to realize a single detergent supply unit 21 or 22, a detergent flow path of which is divided into several paths connected to the plurality of washtubs, to supply detergent into the respective washtubs. In addition, positions of the detergent supply units 21 and 22 are not limited thereto, and the detergent supply units 21 and 22 may be installed at any other positions where the user may easily input detergent.

FIG. 2 illustrates an interior configuration of the washing machine according to the embodiment of the present invention of FIG. 1.

As shown in FIG. 2, in the washing machine according to the embodiment of FIG. 1, the plurality of washtubs (e.g., two washtubs) is vertically divided to enable sorted washing of laundry based on the capacity or type of the laundry. For example, a first washtub 31 for large-capacity washing (e.g., 13 Kg) is provided as a lower washtub, and a second washtub 32 for small-capacity washing (e.g. 3 Kg) is provided as an upper washtub.

Although the first and second washtubs 31 and 32 may have the same capacity range as occasion demands, differentiating the large-capacity and small-capacity washtubs may be more advantageous in consideration of characteristics of the washing machine having the plurality of washtubs 31 and 32. This serves, as mentioned above, to prevent unnecessary power waste by operating only the small-capacity second washtub 32 in the case of washing of a small quantity of laundry.

The first and second washtubs 31 and 32 have the same basic configuration, and cylindrical first and second drums 41 and 42 perforated with a plurality of holes are rotatably installed respectively in the first and second washtubs 31 and 32. Also, first and second motors 61 and 62 are mounted to rear outer surfaces of the first and second washtubs 31 and 32 and serve as drive devices to rotate first and second rotating shafts 51 and 52 connected to the first and second drums 41 and 42, so as to perform washing, rinsing, and dehydrating stages. Of course, the first and second motors 61 and 62 are not limited to the illustrated example, and the respective washtubs may be operated simultaneously or independently using a single motor, drive belt, clutch, etc.

First and second washing heaters 71 and 72 to heat water in the first and second washtubs 31 and 32 are installed respectively in the bottom regions of the first and second washtubs 31 and 32. Also, first and second water supply devices 101 and 102 are installed above the first and second washtubs 31 and 32, to supply water (wash water or rinse water) into the respective washtubs. The first and second water supply devices 101 and 102 include first and second water supply pipes 121 and 122, which connect an external water supply pipe 110 to the first and second detergent supply units 21 and 22 so as to supply water (wash water or rinse water) into the first and second washtubs 31 and 32, and first and second water supply valves 131 and 132 installed on positions of the first and second water supply pipes 121 and 122 to control water supply. With this configuration, water to be supplied into the first and second washtubs 31 and 32 moves by way of the first and second detergent supply units 21 and 22, thereby being supplied into the first and second washtubs 31 and 32 together with detergent in the first and second detergent supply units 21 and 22.

In the embodiment of the present invention, additionally, first and second drying devices 201 and 202 are installed to dry laundry in the first and second washtubs 31 and 32. The first and second drying devices 201 and 202 include first and second drying ducts 211 and 212, which are installed on the first and second washtub 31 and 32 and are used to introduce hot air into the first and second washtubs 31 and 32, first and second condensing ducts 221 and 222, which are installed at the rear side of the first and second washtubs 31 and 32 and are used to remove wet vapor generated in a drying stroke, first and second drying heaters 231 and 232 and first and second drying fans 241 and 242, which are installed in the first and second drying ducts 211 and 212 and are used to supply the hot air, and condensers installed in the first and second condensing ducts 221 and 222. The condensers include first and second ejecting nozzles 281 and 282, which are installed in the first and second condensing ducts 221 and 222 and are used to eject cold water, first and second cold water supply hoses 251 and 252 to supply cold water into the first and second ejecting nozzles 281 and 282, and first and second cold water valves 261 and 262, which are installed on positions of the first and second cold water supply hoses 251 and 252 and are adapted to be opened or closed for supply of cold water. The first and second condensing ducts 221 and 222 have discharge holes formed in the bottoms thereof for discharge of condensed water, and first and second drainpipes 311 and 312 are connected to the discharge holes via first and second drain hoses 271 and 272.

With the above-described configuration, air blown by operation of the first and second drying fans 241 and 242 is supplied into the first and second washtubs 31 and 32 after being heated by the first and second drying heaters 231 and 232, thereby acting to heat and dry laundry in the washtubs. Then, moisture contained in wet vapor generated in the drying of laundry may be removed while the wet vapor is suctioned to the first and second drying fans 241 and 242 through the first and second condensing ducts 221 and 222.

The first and second condensing ducts 221 and 222 define flow-paths extending between first and second air outlets 291 and 292 formed near the rear bottoms of the first and second washtubs 31 and 32 and suction ports of the first and second drying fans 241 and 242 installed on the first and second washtubs 31 and 32. The first and second condensing ducts 211 and 222 are bent by a predetermined curvature, an open side of each of which comes into direct contact with the rear surface of the first or second washtub 31 or 32 and the suction port of the first or second drying fan 241 or 242. Accordingly, the first and second drying fans 241 and 242 are operated to circulate air in, e.g., the drying stroke through the first and second air outlets 291 and 292 of the first and second washtubs 31 and 32, first and second condensing ducts 221 and 222, first and second drying fans 241 and 242, first and second drying ducts 211 and 212, and air inlets of the first and second washtubs 31 and 32 in sequence. The water supplied into the first and second condensing ducts 221 and 222 moves through the first and second condensing ducts 221 and 222 and is collected in the first and second washtubs 31 and 32. The collected water is periodically pumped so as to be drained to the outside by first and second drain devices 301 and 302 that will be described hereinafter, or is moved into and stored in the first or second wash tub (i.e. a washtub that is not in operation) by a water moving device 500 that will be described hereinafter. Here, the non-operating washtub denotes a washtub not actively under control, such as, e.g., a washtub stopped in operation or washtub before a washing stroke. Although details will be given hereinafter, the reason for moving water into the non-operating washtub is that the non-operating washtub has fewer control obstructing factors, such as, e.g., wetting of laundry and increase in the supply quantity of water. Reference numerals 81 and 82 represent first and second water-level sensors, which serve to sense the level of water generated in the drying stage.

Although this embodiment of the present invention employs the first and second drying devices 201 and 202 to dry laundry in the respective first and second washtubs 31 and 32, the drying device 211 or 212 may be mounted to only one of the first and second washtubs 31 and 32 based on the design of the washing machine. For example, the first drying device 201 may be mounted to only the first washtub 31. In this case, a pump 503 may be omitted. Alternatively, the second drying device 202 may be mounted to only the second washtub 32.

In this embodiment of the present invention, the first and second drain devices 301 and 302 are installed to drain water received in the first and second washtubs 31 and 32. The first and second drain devices 301 and 302 include the first and second drainpipes 311 and 312 connected to the bottoms of the first and second washtubs 31 and 32 so as to guide the water to the outside, and first and second drain pumps 321 and 322 installed on the first and second drainpipes 311 and 312. Each of the first and second drain devices 301 and 302 communicates with an external drainpipe 330.

Although this embodiment of the present invention employs the first and second drain pumps 321 and 322 to drain water from the first and second washtubs 31 and 32, the upper washtub of the washing machine, i.e. the second washtub 32 may be provided with a drain valve based on the configuration of the washing machine, allowing water in the second washtub 32 to be drained according to gravity.

In the embodiment of the present invention, the water moving device 500 is provided to move water from an operating washtub to a non-operating washtub, for example, to move water from the first washtub 31 to the second washtub 32, or vice versa. In this case, the water generated in the drying operation includes water supplied from an external water source, and condensed water obtained as moisture contained in air discharged from the washtub is condensed by the supplied water. The water moving device 500 includes a connecting pipe 501 to connect the first drainpipe 311 of the first washtub 31 to the second drainpipe 312 of the second washtub 32, and an opening/closing valve 502 and the pump 503 installed on the connecting pipe 501. The connecting pipe 501 connects a front end of the first drain pump 321 on the first drainpipe 311 of the first washtub 31 to a front end of the second drain pump 322 on the second drainpipe 312 of the second washtub 32. In this case, the connecting pipe 501 may connect the first condensing duct 211 of the first washtub 31 to the second condensing duct 222 of the second washtub 32 by connecting the first drain hose 271 and second drain hose 272 to each other.

One end of the connecting pipe 501 may be connected to any one or both of the first drainpipe 311 and first condensing duct 221, and the other end of the connecting pipe 501 may be connected to any one or both of the second drainpipe 312 and second condensing duct 222. That is, the connecting pipe 501 may connect a drainpipe of an operating washtub to a drainpipe of a non-operating washtub, a condensing duct of the operating washtub to the drainpipe of the non-operating washtub, the drainpipe of the operating washtub to a condensing duct of the non-operating washtub, or the condensing duct of the operating washtub to the condensing duct of the non-operating washtub.

The connecting pipe 501 is provided with the opening/closing valve 502 and pump 503. For example, the opening/closing valve 502 may be located near a junction of the connecting pipe 501 and second drainpipe 312. In this case, when it is unnecessary to direct water from the first washtub 31 to the second washtub 32 through the connecting pipe 501, it may be possible to reduce the quantity of water filled in a region of the connecting pipe 501 communicating with the first drainpipe 311. Also, the pump 503 may be located near a junction of the connecting pipe 501 and first drainpipe 311. In this case, when it is necessary to direct water from the second washtub 32 to the first washtub 31 through the connecting pipe 501, enhanced pumping efficiency may be accomplished. The enhanced pumping efficiency may also be accomplished even when it is necessary to direct water from the second washtub 32 to the first washtub 31 later.

FIG. 3 illustrates a schematic control configuration of the washing machine according to the embodiment of the present invention of FIG. 1.

As shown in FIG. 3, the washing machine according to this embodiment of the present invention includes the input unit 400, a controller 402, and a drive unit 404.

The input unit 400 is used to input operational information, related to washing courses and washing functions (e.g., simultaneous washing/drying or independent washing/drying) of the first and second washtubs 31 and 32 that are selected to be simultaneously or independently used, into the controller 402. The controller 402 controls respective devices of the washing machine in response to commands input by the user via the input unit 400. For example, to perform washing/dehydrating/drying strokes, the controller 402 may control devices for the washing/dehydrating/drying strokes, i.e. the first and second motors 61 and 62, first and second washing heaters 71 and 72, first and second water supply valves 131 and 132, first and second drying heaters 231 and 232, first and second drying fans 241 and 242, first and second cold water valves 261 and 262, first and second drain pumps 321 and 322, opening/closing valve 502, and pump 503. In a control method as will be described hereinafter, the controller 402 determines the operating stages of the first and second washtubs 31 and 32 and also, determines whether or not the respective devices are in operation.

The first and second water-level sensors 81 and 82 are installed close to the first and second air outlets 291 and 292 that are formed near the rear bottoms of the first and second washtubs 31 and 32 and serve to sense the level of water generated in the drying stage.

The controller 402 determines whether or not the first washtub 31 and second washtub 32 are in operation. If any one washtub is in operation and the other washtub is not in operation, the controller 402 moves water used in the operation, e.g., moves water from the operating washtub into the non-operating washtub, allowing the water to be stored in the non-operating washtub. More particularly, the controller 402 determines the presence of a washtub that is in operation. If the presence of the washtub that is in operation is determined, the controller 402 determines whether or not it is necessary to move water used in the operating washtub. If the movement of water used in the operating tub is necessary, the controller 402 moves the water from the operating washtub into a washtub that is not in operation, so as to store the water in the non-operating washtub.

For example, the controller 402 determines whether or not the first washtub 31 and second washtub 32 are in operation. If any one washtub is in the last rinsing stage and the other washtub is not in operation, the controller 402 moves water used in the last rinsing stage into the non-operating washtub, so as to store the water in the non-operating washtub. Since the rinse water used in the last rinsing stage is relatively clean, the rinse water may be recycled later as wash water or rinse water, enabling remarkable reduction in the usage of water in the washing machine. For example, if the first washtub 31 is in the last rinsing stage and the second washtub 32 is not in operation, the water used in the last rinsing stage is moved into and stored in the second washtub 32. In this case, if the second washtub 32 is in operation, the water in the first washtub 31 is discharged to the outside. On the contrary, if the second washtub 32 is in the last rinsing stage and the first washtub 31 is not in operation, the water used in the last rinsing stage is moved into and stored in the first washtub 31. In this case, if the first washtub 31 is in operation, the water in the second washtub 32 is discharged to the outside.

In addition, the controller 402 determines whether or not the first washtub 31 and second washtub 32 are in operation. If any one washtub is in the drying stage and the other washtub is not in operation, the controller 402 moves water generated in the drying stage into the non-operating washtub, so as to store the water in the non-operating washtub. Similar to the above-described rinse water, since the water generated in the drying stage is relatively clean, it may be recycled later as wash water or rinse water, enabling remarkable reduction in the usage of water in the washing machine. For example, if the first washtub 31 is in the drying stage and the second washtub 32 is not in operation, the water generated in the drying stage is moved into and stored in the second washtub 32. In this case, if the second washtub 32 is in operation, the water in the first washtub 31 is discharged to the outside. On the contrary, if the second washtub 32 is in the drying stage and the first washtub 31 is not in operation, the water generated in the drying stage is moved into and stored in the first washtub 31. In this case, if the first washtub 31 is in operation, the water in the second washtub 32 is discharged to the outside. The controller 402 senses the level of water generated in the drying stage and if the sensed level of water is a preset value or more, moves the water generated in the drying stage into the non-operating washtub, so as to store the water in the non-operating washtub.

After moving the water used in the operating washtub so as to store the water in the non-operating washtub, the controller 402 determines whether or not the first washtub 31 and second washtub 32 are in operation. If there is a washtub to be newly operated, the controller 402 moves the water stored in the non-operating washtub into the washtub to be newly operated, allowing the water to be used for a washing or rinsing stage. In this case, the water stored in the non-operating washtub is moved into the washtub to be newly operated before the newly operated washtub performs any one of washing and rinsing stages or during the washing or rinsing stage. If the newly operated washtub corresponds to the previous non-operating washtub and thus, receives water already, it may be impossible for the user to open a door of the washtub. Therefore, it may be necessary to move the stored water into an additional washtub and then, to return the water into the original washtub after completion of, e.g., laundry input and door closing operations.

The drive unit 404 serves to drive, e.g., the first and second motors 61 and 62, first and second washing heaters 71 and 72, first and second water supply valves 131 and 132, first and second drying heaters 231 and 232, first and second drying fans 241 and 242, first and second cold water valves 261 and 262, first and second drain pumps 321 and 322, opening/closing valve 502, and pump 503, based on drive control signals of the controller 402.

Hereinafter, a control method of the washing machine according to the embodiment of the present invention will be described with reference to FIG. 4.

If both washtubs are performing the last rinsing stroke, or if any one of the washtubs is performing the last rinsing stroke and the other washtub is in operation, a conventional control method is implemented. However, if one washtub is performing the last rinsing stroke and the other washtub is not in operation, the control method of the washing machine according to this embodiment of the present invention is utilized.

FIG. 4 illustrates a control operation of the washing machine according to the present embodiment of the present invention.

Referring to FIG. 4, the controller 402 first determines whether or not the first washtub 31 and second washtub 32 are in operation (600). In this case, the controller 402 determines whether the first washtub 31 or the second washtub 32 is in the last rinsing stage.

Then, the controller 402 determines, based on the determined result of the operation mode 600, whether or not any one of the first washtub 31 and second washtub 32 is in the last rinsing stage (610).

After determining the presence of the washtub that is in the last rinsing stage, the controller 402 determines whether or not the first washtub 31 is in the last rinsing stage (620). If the determined result shows that the first washtub 31 is in the last rinsing stage, the controller 402 determines whether or not the second washtub 32 is not in operation (630).

If the second washtub 32 is not in operation, the controller 402 opens the opening/closing valve 502 of the water moving device 500 and rotates the pump 503 forward, moving rinse water of the first washtub 31 used in the last rinsing stage into the second washtub 32 so as to store the rinse water in the second washtub 32 (640) (See FIG. 5). Thereby, the water may be recycled when the second washtub 32 performs a washing stage or rinsing stage later. In addition, to recycle the water when the first washtub 31 performs a following washing stage or rinsing stage, the water may be returned into the first washtub 31 by the water moving device 500. This may consequently reduce the usage of water in the washing machine.

If it is determined, based on the determined result of the operation mode 630, that the second washtub 32 is in operation, the controller 402 turns on the first drain pump 321 to discharge the rinse water of the first washtub 31 to the outside, in order to prevent the rinse water from having an effect on operation of the second washtub 32 (650).

Meanwhile, if it is determined, based on the determined result of the operation mode 620, that the first washtub 31 is not in the last rinsing stroke, the controller 420 determines that the second washtub 32 is in the last rinsing stroke and thus, determines whether or not the first washtub 31 is not in operation (660).

If it is determined, based on the determined result of the operation mode 660, that the first washtub 31 is not in operation, the controller 402 opens the opening/closing valve 502 of the water moving device 500 and rotates the pump 503 rearward, moving the rinse water of the second washtub 33 into the first washtub 31 so as to store the rinse water in the first washtub 31 (670). The water may be recycled when the first washtub 31 performs a following washing stage or rinsing stage. In addition, to recycle the water when the second washtub 32 performs a following washing stage or rinsing stage, the water may be directed into the second washtub 32 by the water moving device 500. This may consequently reduce the usage of water in the washing machine.

Meanwhile, if it is determined, based on the determined result of the operation mode 660, that the first washtub 31 is in operation, the controller 402 turns on the second drain pump 322 to discharge the rinse water of the second washtub 32 to the outside, to prevent the rinse water from having an effect on operation of the first washtub 31 (650).

If the first washtub is in the last rinsing stroke as described above or is in the drying stroke, the water used in the last rinsing stroke or generated in the drying stroke is moved into and stored in the second washtub that is not in operation. In this case, as shown in FIG. 6, the water stored in the second washtub functions as a so-called balance weight, acting to reduce the vibration and noise of the entire washing machine. This is equally applicable to the case where the water used in the last rinsing stroke and generated in the drying stroke is moved into and stored in the first washtub that is not in operation. The water moved into the non-operating washtub is stored until the operating washtub is stopped.

Hereinafter, a control method of a washing machine according to another embodiment of the present invention will be described with reference to FIG. 7.

If both washtubs are performing the drying stroke, or if any one of the washtubs is performing the drying stroke and the other washtub is in operation, a conventional control method is implemented. However, if one washtub is performing the drying stroke and the other washtub is not in operation, the control method of the washing machine according to the present embodiment is utilized.

Hereinafter, for convenience of description, the following description is based on an application example of the control method in the case where the drying devices 201 and 202 are installed to the respective first and second washtubs 31 and 32. However, the control method is equally applicable even to the case where a single drying device is installed to the first washtub 31 or the second washtub 32.

FIG. 7 illustrates the control operation of the washing machine according to another embodiment of the present invention.

Referring to FIG. 7, the controller 402 first determines whether or not the first washtub 31 and second washtub 32 are in operation (700). In this case, the controller 402 determines whether the first washtub 31 or the second washtub 32 is in the drying stage.

Then, the controller 402 determines, based on the determined result of the operation mode 700, whether or not any one of the first washtub 31 and second washtub 32 is in the drying stage (710).

After determining the presence of the washtub that is in the drying stage, the controller 402 determines whether or not the first washtub 31 is in the drying stage (720). If the determined result shows that the first washtub 31 is in the drying stage, the controller 402 determines whether or not the second washtub 32 is not in operation (730).

If the second washtub 32 is not in operation, the controller 402 opens the opening/closing valve 502 of the water moving device 500 and rotates the pump 503 forward, moving condensed water of the first washtub 31 (generated in the drying stage) into the second washtub 32 so as to store the condensed water in the second washtub 32 (740) (See FIG. 8). The water may be recycled when the second washtub 32 performs a following washing stage or rinsing stage. In addition, to recycle the water when the first washtub 31 performs a following washing stage or rinsing stage, the water may be returned into the first washtub 31 by the water moving device 500. This consequently may reduce the usage of water in the washing machine.

Meanwhile, if it is determined, based on the determined result of the operation mode 730, that the second washtub 32 is in operation, the controller 402 turns on the first drain pump 321 to discharge the condensed water of the first washtub 31 to the outside, in order to prevent the condensed water from having an effect on operation of the second washtub 32 (750).

If it is determined, based on the determined result of the operation mode 720, that the first washtub 31 is not in the drying stage, the controller 420 determines that the second washtub 32 is in the drying stage and thus, determines whether or not the first washtub 31 is not in operation (760).

If it is determined, based on the determined result of the operation mode 760, that the first washtub 31 is not in operation, the controller 402 opens the opening/closing valve 502 of the water moving device 500 and rotates the pump 503 rearward, moving condensed water of the second washtub 32 into the first washtub 31 so as to store the condensed water in the first washtub 31 (770). The water may be recycled when the first washtub 31 performs a following washing stroke or rinsing stroke. In addition, to recycle the water when the second washtub 32 performs a following washing stroke or rinsing stroke, the water may be returned into the second washtub 32 by the water moving device 500. This consequently may reduce the usage of water in the washing machine.

Meanwhile, if it is determined, based on the determined result of the operation mode 760, that the first washtub 31 is in operation, the controller 402 turns on the second drain pump 322 to discharge the condensed water of the second washtub 32 to the outside, in order to prevent the condensed water from having an effect on operation of the first washtub 31 (750).

If the first washtub is in the last rinsing stroke or is in the drying stroke as described above, the water used in the last rinsing stroke or generated in the drying stroke is moved into and stored in the second washtub that is not in operation. In this case, as shown in FIG. 9, the water stored in the second washtub functions as a so-called balance weight, acting to reduce the vibration and noise of the entire washing machine. This is equally applicable to the case where the water used in the last rinsing stroke and generated in the drying stroke is moved into and stored in the first washtub that is not in operation. The water moved into the non-operating washtub is stored until the operating washtub is stopped.

Also, although the present embodiment illustrates that the water of one washtub that is in the last rinsing stroke or in the drying stroke is moved into and stored in the other wash tub that is not in operation, thus acting as a so-called balance weight in the non-operating washtub, the present embodiment is not limited thereto. Simply acquiring the above-described balance weight via movement of water between both washtubs may be possible even when water is newly supplied into one washtub that is not in operation while the other washtub is in operation. In this case, the operating washtub may also include a washtub that is performing a washing, rinsing (initial rinsing or middle rinsing), or dehydrating stage except for the last rinsing stage or the drying stage. In addition, the operating washtub may include a washtub that is performing any one of a washing stage, rinsing stage, dehydrating stage, and drying stage.

Although the above described embodiments describe the movement of water from the operating washtub into the non-operating washtub, the embodiments of the present invention are not limited thereto, and water used in one washtub that is in operation may be moved into the other washtub that is in operation. For example, if it is necessary to supply water into the second washtub for a washing or rinsing stage while the first washtub is performing the last rinsing stage, the water used in the first washtub may be moved into the second washtub.

Hereinafter, a method of recycling the water moved into the non-operating washtub will be described specifically. For convenience of description, the following description is based on the case where two washtubs are provided, only one of which stores water therein, and both the washtubs are initially not in operation.

FIG. 10 illustrates an operation of moving water stored in one washtub into the other washtub to be newly operated in a washing machine according to a further embodiment of the present invention.

Referring to FIG. 10, the controller 402 determines whether or not any one of the first washtub 31 and second washtub 32 stores water (800).

If the presence of the washtub in which water is stored is determined, the controller 402 determines whether or not the first washtub 31 and second washtub 32 are in operation (801).

Then, the controller 402 determines, based on the determined result of the operation mode 801, whether or not any one of the first washtub 31 and second washtub 32 will be newly operated (802). Here, the washtub to be newly operated is a washtub that will begin a washing stage or rinsing stage.

If the presence of the washtub to be newly operated is determined, the controller 402 determines whether or not the washtub to be newly operated is the first washtub 31 (803).

If the washtub to be newly operated is the first washtub 31, the controller 402 determines whether or not the washtub in which water is stored is the first washtub 31 (804).

If the washtub in which water is stored is the first washtub 31, the controller 402 moves the water of the first washtub 31 into the second washtub 32 (805). This serves to prevent spillage of water when the user opens the door of the first washtub 31 for washing, or to prevent unwanted locking of the door due to the stored water before the user puts laundry into the first washtub because the washtub to be newly operated corresponds to the washtub in which water is stored.

After moving the water from the first washtub 31 into the second washtub 32, the controller 402 determines whether or not the input of laundry is completed (806). If the input of laundry is completed, the controller 402 returns the water from the second washtub 32 into the first washtub 31 (807). The returned water is recycled for operation of the first washtub 31.

On the contrary, if the washtub in which water is stored is the second washtub 32, the controller 402 determines whether or not the input of laundry into the first washtub 31 is completed (806). If the input of laundry is completed, the controller 402 moves the water from the second washtub 32 into the first washtub 31 (807). Accordingly, the stored water is recycled for operation of the first washtub 31.

If the washtub to be newly operated is the second washtub 32, the controller 402 determines whether or not the washtub in which water is stored is the second washtub 32 (808).

If the washtub in which water is stored is the second washtub 32, the controller 402 moves the water from the second washtub 32 into the first washtub 31 (809). This serves to prevent spillage of water when the user opens the door of the second washtub 32 for washing or to prevent unwanted locking of the door due to the stored water before the user puts laundry into the second washtub 32 because the washtub to be newly operated corresponds to the washtub in which water is stored.

After moving the water from the second washtub 32 into the first washtub 31, the controller 402 determines whether or not the input of laundry is completed (810). If the input of laundry is completed, the controller 402 returns the water from the first washtub 31 into the second washtub 32 (811). The returned water is recycled for operation of the second washtub 32.

On the contrary, if the first washtub 31 stores water, the controller 402 determines whether or not the input of laundry into the second washtub 32 is completed (810). If the input of laundry is completed, the controller 402 moves the water from the first washtub 31 into the second washtub 32 (811). Accordingly, the stored water is recycled for operation of the second washtub 32.

As is apparent from the above description, according to an embodiment of the present invention, rinse water used in the last rinsing stroke or condensed water generated in a drying stroke may be moved into and stored in a washtub that is not in operation, rather than being drained. This allows dozens of liters of water to be recycled in a following washing stroke or rinsing stroke of the washtub or a washing stroke or rinsing stroke of an additional washtub, resulting in considerable reduction in the usage of water in a washing machine.

Further, according to another embodiment of the present invention, water used in one washtub that is in operation may be moved into and stored in the other washtub that is not in operation, or newly supplied water may be stored in the non-operating washtub. The water stored in the non-operating washtub may serve as a so-called balance weight of the entire washing machine, acting to reduce the vibration and noise of the entire washing machine.

Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims

1. A control method of a washing machine having a plurality of washtubs, the method comprising:

determining whether or not a washtub that is in operation is present; and

if the presence of the washtub that is in operation is determined, moving water used in the washtub that is in operation to a washtub that is not in operation.

2. The control method according to claim 1, wherein the determining of the presence of the washtub that is in operation includes determining whether or not a washtub that is performing any one of a washing stage, rinsing stage, dehydrating stage, and drying stage is present.

3. The control method according to claim 2, wherein the determining of the presence of the washtub that is in operation includes determining whether or not a washtub that is in a last rinsing stage is present.

4. The control method according to claim 2, wherein the determining of the presence of the washtub that is in operation includes determining whether or not a washtub that is in the drying stage is present.

5. The control method according to claim 4, further comprising:

sensing a level of water generated in the drying stage of the washtub that is in operation; and

moving the water generated in the drying stage to the washtub that is not in operation if the sensed level of water is a preset value or more.

6. The control method according to claim 1, further comprising:

storing the water moved into the washtub that is not in operation until the washtub that is in operation is stopped.

7. The control method according to claim 5, further comprising returning the water, moved into the washtub that is not in operation, when the washtub that is in operation performs any one of a following washing stroke and rinsing stroke.

8. A control method of a washing machine having a plurality of washtubs, the method comprising:

determining whether or not a washtub that is in operation is present;

if the presence of the washtub that is in operation is determined, determining whether or not movement of water used in the operation is needed; and

if movement of the water used in the operation is needed, moving the water used in the operation to a washtub that is not in operation.

9. The control method according to claim 8, wherein the determining whether movement of the water used in the operation is needed includes determining whether or not the washtub that is in operation completes a last rinsing stage, and determining whether or not a level of water generated in a drying stage reaches a preset value.

10. A washing machine comprising:

a plurality of washtubs including a washtub that is in operation and an additional washtub;

a water moving device to move water between the plurality of washtubs; and

a controller to control the water moving device to move the water used in a washtub that is in operation to an additional washtub.

11. The washing machine according to claim 10, wherein the controller moves the water used in the washtub that is in operation, during a last rinsing stage or a drying stage, into the additional washtub, is the additional washtub not being in operation.

12. The washing machine according to claim 10, wherein the controller moves the water used in the washtub that is in operation, during any one of a washing stage, rinsing stage, dehydrating stage, and drying stage to the additional washtub, the additional washtub not being in operation.

13. The washing machine according to claim 10, wherein the water moved into the additional washtub is stored under control of the controller until the washtub that is in operation is stopped.

14. The washing machine according to claim 13, wherein the controller returns the water moved into the additional washtub when the washtub that is in operation performs any one of a following washing stage and rinsing stage.

15. The washing machine according to claim 10, wherein the water moving device includes at least one connecting pipe connecting the plurality of washtubs to each other, and an opening/closing valve and pump provided at the connecting pipe.

16. The washing machine according to claim 15, wherein the connecting pipe has one end connected to at least one of a drainpipe and condensing duct of the washtub that is in operation, and the other end connected to at least one of a drainpipe and condensing duct of the additional washtub.