Patent Description:
Generally, a washing machine has on a front surface of a casing an input port for putting laundry into a drum which is rotatably installed in the casing, and has a door for opening and closing the input port. A portion of a rear surface of the door is in close contact with the front surface of the casing, and another portion of the rear surface protrudes rearwards to be inserted into the input port, thus preventing laundry or water contained in the drum from leaking to an outside through the input port.

Korean Patent Laid-Open Publication <CIT> has disclosed a washing machine including a wash reinforcement nozzle which sprays wash water into a drum, and a door wash nozzle which sprays wash water onto a door.

This washing machine is problematic in that a spray range through the wash reinforcement nozzle is restricted, so an area where washing cannot be performed occurs on an inner surface of the drum, and water sprayed from the wash reinforcement nozzle reaches only an interior of the drum, so it is difficult to wash an outer surface of the drum or an inner surface of a tub surrounding the drum.

<CIT>) relates to a method of cleaning a rotatably mounted washing machine drum which receives laundry to be washed.

First, an objective of the present disclosure is to provide a method of controlling a washing machine, which is improved in drum cleaning capability.

Second, an objective of the present disclosure is to provide a method of controlling a washing machine, which can cleanly wash an outer surface of a drum.

Third, an objective of the present disclosure is to provide a method of controlling a washing machine, which can cleanly wash an inner surface of a tub.

The present invention is defined by claim <NUM>.

The step (e) may include a step of repeating a first drum cleaning operation in which the drum is rotated at least once at a third set speed lower than the second set speed, and a second drum cleaning operation in which the drum is rotated at least once at a fourth set speed lower than the third set speed.

The step (b) may further include a step of feeding steam into the drum.

A water supply amount at the step (d) may be greater than a water supply amount at the step (a).

The first set speed may range from <NUM> to <NUM> rpm.

The second set speed may range from <NUM> to <NUM> rpm.

The third set speed may range from <NUM> to <NUM> rpm.

The step (e) may further include a step of repeating a third drum cleaning operation in which the drum is rotated at least once at the second set speed, and a fourth drum cleaning operation in which the drum is rotated at least once at the third set speed.

The method may further include a step of draining the tub after the step (e); and a step of feeding water into the drum through a direct water nozzle while rotating the drum at a speed higher than the first set speed.

The operation of the heater at the step (b) may be controlled such that a temperature of water contained in the tub reaches a first set temperature defined between <NUM> and <NUM>.

The operation of the heater at the step (e) may be controlled such that the temperature of water contained in the tub reaches a second set temperature higher than the first set temperature.

The fourth set speed may range from <NUM> to <NUM> rpm.

The control method of the washing machine according to the present disclosure is advantageous in that a heater is operated to sterilize water in a tub, thus providing good hygiene, and the rotating speed of a drum is controlled in this process to generate a water current moved upwards in a tub by friction with the drum, thus allowing both an outer surface of the drum and an inner surface of the tub to be evenly cleaned.

The above and other objectives, features, and advantages of the present disclosure will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings. However, the present disclosure may be embodied in other aspects without being limited to the embodiments disclosed below. The embodiments are provided to make the present disclosure complete and to sufficiently convey the scope of the present disclosure to those skilled in the art without departing from the scope of the claims. In the present specification, it should be noted that the same reference numerals are used to denote the same components throughout different drawings.

<FIG> is a perspective view of a washing machine according to an embodiment of the present disclosure. <FIG> is a side sectional view of the washing machine illustrated in <FIG>. <FIG> is a block diagram illustrating a control relationship between main components of the washing machine according to an embodiment of the present disclosure. <FIG> is a graph illustrating a method of controlling a washing machine according to an embodiment of the present disclosure.

Referring to <FIG>, a casing <NUM> defines the appearance of the washing machine, and an input port <NUM> is formed in a front surface of the casing to put laundry therein. The casing <NUM> may include a cabinet <NUM> which is opened at a front surface thereof and has a left surface, a right surface, and a rear surface, and a front panel <NUM> which is coupled to the open front surface of the cabinet <NUM>, with the input port <NUM> being formed thereon.

The lower surface and the upper surface of the cabinet <NUM> may be opened, and a horizontal base <NUM> may be coupled to the lower surface to support the washing machine. The casing <NUM> may further include a top plate <NUM> which covers the open upper surface of the cabinet <NUM>, and a control panel <NUM> which is disposed on an upper portion of the front panel <NUM>.

A tub <NUM> may be disposed in the casing <NUM> to contain water therein. An inlet is formed in the front surface of the tub <NUM> to allow laundry to be put therein. The cabinet <NUM> and the tub <NUM> are connected by an annular gasket <NUM>, so a passage for putting or taking laundry into or out from the casing is formed in a section extending from the inlet of the tub <NUM> to the input port <NUM>.

The door <NUM> for opening or closing the input port <NUM> may be rotatably coupled to the casing <NUM>. The door <NUM> may include a door frame <NUM> which is opened at a central portion thereof and is rotatably coupled to the front panel <NUM>, and a transparent window <NUM> which is installed in the open central portion of the door frame <NUM>. The window <NUM> may have a rearwardly convex shape, so at least a portion of the window may be located in an area surrounded by an inner circumferential surface of the gasket <NUM>.

The control panel <NUM> may include a display unit 14a which displays the operating state of the washing machine, and an input unit 14b which receives various control commands about the operation of the washing machine from a user.

The gasket <NUM> is formed such that each of front and rear ends has an annular shape, and has the shape of a tube extending from the front end to the rear end. The front end of the gasket <NUM> is secured to the casing <NUM>, and the rear end thereof is secured to the circumference of the inlet of the tub <NUM>. The gasket <NUM> may be made of a flexible or elastic material. The gasket <NUM> may be made of natural rubber or synthetic resin. In a state where the door <NUM> is closed, the front end of the gasket <NUM> is in close contact with the rear surface of the door <NUM>, thus preventing water in the tub <NUM> from leaking through the inlet of the gasket <NUM>.

Hereinafter, a portion defining the inner side of the tubular gasket <NUM> is referred to as an inner circumference (or inner circumferential surface) of the gasket <NUM>, and an opposite portion is referred to as an outer circumference (or outer surface) of the gasket <NUM>.

A drum <NUM> may be rotatably provided in the tub <NUM>. The drum <NUM> holds laundry therein, is disposed such that an inlet for putting laundry is located on a front surface, and rotates about a horizontal axis C. In this regard, the term "horizontal" is not a term used in a mathematically strict sense. That is, although the axis C is inclined at a predetermined angle with respect to a horizontal as in an embodiment, it may be said to be substantially horizontal when the axis is closer to the horizontal rather than vertical. Multiple holes (not shown) are formed in the drum <NUM> to introduce water contained in the tub <NUM> into the drum <NUM>.

A plurality of lifters 32a may be provided on the inner surface of the drum <NUM>. The plurality of lifters 32a may be disposed at a predetermined angle to the center of the drum <NUM>. When the drum <NUM> rotates, the laundry is repeatedly lifted and dropped by the lifters 32a.

A driving unit <NUM> is further provided to rotate the drum <NUM>. A driving shaft 38a rotated by the driving unit <NUM> may be coupled to the drum <NUM> via the rear surface of the tub <NUM>.

Preferably, the driving unit <NUM> includes a direct connected washing motor, and the washing motor may include a stator which is secured to the rear of the tub <NUM>, and a rotor which is rotated by a magnetic force acting between the rotor and the stator. The driving shaft 38a may be rotated integrally with the rotor.

The tub <NUM> may be supported by a damper <NUM> installed at the base <NUM>. The vibration of the tub <NUM> caused by the rotation of the drum <NUM> is attenuated by the damper <NUM>. Although not shown in the drawings, according to an embodiment, a hanger (e.g. spring) may be further provided to hang the tub <NUM> to the interior of the casing <NUM>.

The washing machine may include at least one water supply hose (not shown) which guides water fed from an external water source such as a faucet, and a water supply unit <NUM> which controls to supply water fed through at least one water supply hose to at least one water supply pipe <NUM>.

A dispenser <NUM> may be provided to feed additives such as detergent or a fabric softener into the tub <NUM> or the drum <NUM>. The additives may be classified according to the type and then be accommodated in the dispenser <NUM>. The dispenser <NUM> may include a detergent compartment (not shown) which accommodates the detergent, and a softener compartment (not shown) which accommodates the fabric softener.

At least one water supply pipe <NUM> or <NUM> may be provided to guide water supplied through the water supply unit <NUM>. The water supply unit <NUM> may include at least one feed valve to control at least one water supply pipe <NUM> or <NUM>.

At least one water supply pipe <NUM> or <NUM> may include a main water supply pipe <NUM> which guides water supplied through the water supply hose to the dispenser <NUM>, and a direct water supply pipe <NUM> which guides water supplied through the water supply hose to a direct water nozzle <NUM>.

The at least one feed valve may include at least one main feed valve <NUM> which controls the main water supply pipe <NUM>, and a nozzle feed valve <NUM> which controls the direct water supply pipe <NUM>.

Although not shown in the drawings, the main water supply pipe <NUM> may include a cold-water supply pipe which supplies cold water, a hot-water supply pipe which supplies hot water, a pre-water supply pipe which supplies cold water for prewash, and/or a bleach supply pipe which supplies water to a compartment containing bleach.

At least one main feed valve <NUM> may include a cold-water valve which controls the cold-water supply pipe, a hot-water valve which controls the hot-water supply pipe, and a pre valve which controls the pre-water supply pipe.

Further, the washing machine may include a steam generator <NUM> for feeding steam into the drum <NUM>, and a steam valve for controlling a steam supply pipe which guides water fed to the steam generator <NUM>.

The above-described feed valves are controlled by a control unit <NUM>. Unless otherwise specified, a "control" for various electrically operated components is defined as being made by the control unit <NUM>.

The gasket <NUM> may be provided with the direct water nozzle <NUM> which sprays water into the drum <NUM>. Water supplied through the water supply unit <NUM> is guided to the direct water nozzle <NUM> by the direct-water supply pipe <NUM>. The direct water nozzle <NUM> may be a swirl nozzle or a spray nozzle, but is not necessarily limited thereto.

Water discharged from the dispenser <NUM> is supplied through the water supply bellows <NUM> to the tub <NUM>. A water supply port (not shown) connected to the water supply bellows <NUM> may be formed in a side surface of the tub <NUM>. The water supply bellows <NUM> may be connected to the tub <NUM>, so water discharged from the dispenser <NUM> is primarily supplied to the tub <NUM>. However, some water dropped to the surface of the drum <NUM> may flow through the hole <NUM> into the drum <NUM>. As the level of water in the tub <NUM> is increased due to water supply, the drum <NUM> is submerged in the water. Even in this case, water is fed through the hole <NUM> into the drum <NUM>. In both of these cases, it will be defined as a case in which water is fed into the drum <NUM>.

A drain port may be formed in the tub <NUM> to discharge water, and a drain bellows <NUM> may be connected to the drain port. A pump <NUM> may be provided to pump water discharged from the tub <NUM> through the drain bellows <NUM>. A drain valve <NUM> may be further provided to control the drain bellows <NUM>. Water discharged through the drain bellows <NUM> is discharged through a drain pipe (not shown) to an outside of the washing machine.

The pump <NUM> may selectively perform a drain function of sending water discharged through the drain bellows <NUM> to the drain pipe, and a circulation function of sending water to a circulation pipe <NUM>. A number of techniques for selectively performing the drain function and the circulation function using a single pump are already well known, so a detailed description thereof will be omitted herein.

However, without being limited thereto, a circulation pump which is connected to the circulation pipe <NUM> to circulate water and a drain pump which is connected to the drain pipe to drain water may be separately provided.

The gasket <NUM> is provided with a circulation nozzle <NUM> which sprays water (circulating water) into the drum <NUM>. Water discharged from the pump <NUM> is supplied through the circulation pipe <NUM> to the circulation nozzle <NUM>.

The circulation nozzle <NUM> may be disposed on the gasket <NUM>. Preferably, the circulation nozzle <NUM> is formed integrally with the gasket <NUM>. A plurality of circulation nozzles <NUM> may be formed on the inner circumference of the gasket <NUM>.

A nozzle feed pipe <NUM> may include a tubular duct (not shown) extending along the outer circumference of the gasket <NUM>, and a plurality of discharge ports (not shown) protruding from the duct and passing through the gasket <NUM>. The plurality of discharge ports may supply circulating water to the plurality of circulation nozzles <NUM>, respectively. On the other hand, a heater <NUM> may be further provided to heat water contained in the tub <NUM>. The heater <NUM> may be disposed in the tub <NUM>, and be disposed under the drum <NUM> so as not to interfere with the drum <NUM>.

<FIG> is a graph illustrating a method of controlling a washing machine according to an embodiment of the present disclosure. To be more specific, the graph of <FIG> shows the rotating speed a of the drum, a water level frequency b (the higher the water level is, the lower a water level frequency value is) indicating the level of water contained in the tub <NUM>, an operation c of the drain valve <NUM>, an operation d of the cold-water valve, an operation e of the hot-water valve, an operation f of the pre valve, an operation g of the steam valve, an operation h of the bleach feed valve, a temperature i of water contained in the tub, and a total amount j of water supplied to the tub.

Referring to <FIG>, the method of controlling the washing machine according to an embodiment of the present disclosure includes a step S1 of supplying water to submerge at least a portion of the drum <NUM> into the tub <NUM>, and a step S2 of performing at least once an operation in which water contained in the tub <NUM> is heated by operating the heater <NUM> and the drum <NUM> is rotated at a first set speed.

At step S1, at least one main feed valve <NUM> is opened to supply water. The control unit <NUM> may shut off the main feed valve <NUM>, if it is determined that water has been supplied by a first set water supply amount (e.g., <NUM>) based on the water level frequency sensed by a water level sensor <NUM>. In a state where water is supplied by the first set water supply amount, the level of water in the tub <NUM> is higher than a level at which the lowermost end of the drum <NUM> contacts.

The water supply is stopped, and step S2 is performed. At step S2, the heater <NUM> is operated to heat water contained in the tub <NUM>. At this time, an operation in which the drum <NUM> is rotated at the first set speed for a predetermined time and then is stopped is repeated several times. The first set speed may range from <NUM> to <NUM> rpm, and preferably be <NUM> rpm.

Water contained in the tub <NUM> moves upwards along the inner surface of the tub <NUM> by friction action with the drum <NUM>. At this time, the water current is wound in the rotating direction of the drum <NUM>, and thus, the outer surface of the drum <NUM> and the inner surface of the tub <NUM> are washed by the water current.

At step S2, water may be supplied through the steam generator <NUM> while the drum <NUM> is repeatedly rotated and stopped. The steam valve is turned on to supply water to the steam generator <NUM>, and steam generated by the steam generator <NUM> is sprayed into the drum <NUM>. The amount of water supplied by the steam generator <NUM> may be approximately <NUM>, but is not necessarily limited thereto.

At step S2, the heater <NUM> may be controlled such that the temperature of water contained in the tub <NUM> reaches the first set temperature. A temperature sensor <NUM> may be provided to sense the temperature of water in the tub <NUM>, and the control unit <NUM> may control the operation of the heater <NUM> based on the sensing value of the temperature sensor.

The first set temperature may be a value defined between <NUM> to <NUM>. The drum <NUM> and the tub <NUM> may be sterilized by hot water which is heated by the heater <NUM>. Particularly in this temperature range, most bacteria are killed, so hygiene is improved. In an embodiment, the first set temperature is <NUM>, but is not necessarily limited thereto.

The operation of the heater <NUM> is stopped, and water contained in the tub <NUM> is drained (cf. portion indicated by "drain" in <FIG>). The drain valve <NUM> is opened, and the pump <NUM> is operated, thus draining water.

Subsequently, water is fed again into the tub <NUM>. As in step S1, at least a portion of the drum <NUM> is submerged in water contained in the tub <NUM> (S3).

At step S3, at least one main feed valve <NUM> is opened to supply water. The control unit <NUM> may shut off the main feed valve <NUM>, if it is determined that water has been supplied by a second set water supply amount (e.g., <NUM>) based on the water level frequency sensed by the water level sensor <NUM>. In a state where water is supplied by the second set water supply amount, the level of water in the tub <NUM> is higher than a level at which the lowermost end of the drum <NUM> contacts. The second set water supply amount may be greater than the first set water supply amount at step S1.

The water supply is stopped, and step S4 is performed. At step S4, the heater <NUM> is operated to heat water contained in the tub <NUM>. At this time, an operation in which the drum <NUM> is rotated for a predetermined time and then is stopped is repeated several times.

Step S4 includes a step of rotating the drum <NUM> at a second set speed at least once. The second set speed is lower than the first set speed, may range from <NUM> to <NUM> rpm, and preferably be <NUM> rpm. At step S4, an operation in which the drum <NUM> is rotated at the second set speed and then is stopped may be repeated several times.

At step S5 performed subsequent to step S4, a first drum cleaning operation and a second drum cleaning operation may be repeatedly performed.

The first drum cleaning operation is to rotate the drum <NUM> at a third set speed lower than the second set speed at least once. The third set speed may range from <NUM> to <NUM> rpm, and preferably be <NUM> rpm. An operation in which the drum <NUM> is rotated at the third set speed for a predetermined time and then is stopped may be repeated several times.

The second drum cleaning operation is to rotate the drum <NUM> at a fourth set speed lower than the third set speed at least once. The fourth set speed may range from <NUM> to <NUM> rpm, and preferably be <NUM> rpm. An operation in which the drum <NUM> is rotated at the fourth set speed for a predetermined time and then is stopped may be repeated several times.

On the other hand, the operation of the heater <NUM> may be controlled such that the water temperature in the tub <NUM> reaches the preset second set temperature while step S5 is performed. Here, the second set temperature may be defined between <NUM> and <NUM> similarly to the first set temperature. Preferably, the second set temperature may be higher than the first set temperature. In an embodiment, the second set temperature is <NUM>, but is not necessarily limited thereto.

Step S6 is performed subsequent to step S5. Step S6 is a step of repeatedly performing a third drum cleaning operation of rotating the drum <NUM> at the second set speed at least once, and a fourth drum cleaning operation of rotating the drum <NUM> at the third set speed at least once. The operation of the heater <NUM> may be controlled such that the water temperature in the tub <NUM> reaches the second set temperature while step S6 is performed.

Step S7 is performed to drain the tub <NUM> subsequent to step S6. At step S7, the drain valve <NUM> is opened, and the pump <NUM> is operated to discharge water.

After stopping to discharge water, a water supply step S8 is performed. At least one main feed valve <NUM> is opened to supply water.

Thereafter, step S9 of adding water to the drum <NUM> through the direct water nozzle <NUM> is performed while the drum <NUM> is rotated at high speed. At this time, the rotating speed of the drum <NUM> is higher than the first set speed, and is increased up to preferably <NUM> rpm. While water sprayed with strong water pressure through the direct water nozzle <NUM> is repelled by the drum <NUM>, the inner surface of the drum <NUM> may be powerfully washed. In addition, water scattered to an outside of the drum <NUM> powerfully washes the inner surface of the tub <NUM> by rotating the drum <NUM>. While step S9 is performed, a drain step S10 may be performed.

Step S9 and step S10 may be repeated one or more times. Subsequently, step S11 of discharging residual water may be further performed while the drum <NUM> is rotated at low speed of <NUM> rpm or less.

On the other hand, the washing machine may include an input unit (not shown) to allow a user to select and input a drum cleaning course. The above-described control method may be performed when the drum cleaning course is selected through the input unit.

Claim 1:
A method of controlling a washing machine configured such that a drum (<NUM>) having on a front surface thereof an inlet through which laundry is put is rotatably provided in a tub (<NUM>) containing water, the method comprising:
(a) a step of supplying water to submerge at least a portion of the drum (<NUM>) in the tub (<NUM>);
(b) a step of performing at least once an operation in which the water contained in the tub (<NUM>) is heated by operating a heater (<NUM>) and the drum (<NUM>) is rotated at a first set speed;
(c) a step of draining the tub (<NUM>);
(d) a step of supplying water to submerge at least a portion of the drum (<NUM>) in the tub (<NUM>),
wherein a water supply amount at the step (d) is greater than a water supply amount at the step (a); and
(e) a step of performing at least once an operation in which the water contained in the tub (<NUM>) is heated by operating the heater (<NUM>) and the drum (<NUM>) is rotated at a second set speed which is lower than the first set speed.