Washing machine and control method thereof

A washing machine and a control method thereof to achieve washing performance using bubbles without damage to fiber structures of functional clothes. When a washing course of functional clothes is selected, a motor is frequently rotated at a period of a predetermined time or less, causing the clothes to uniformly adsorb the water. Thereafter, bubbles are generated and applied to the clothes. A drive operation rate of the motor is raised stepwise to wash the clothes to which the bubbles have been applied, so as to effectively remove sweat, contaminants, or the like contained in the clothes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 2009-0085296, filed on Sep. 10, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Embodiments relate to a washing machine and a control method thereof to achieve washing performance using bubbles without damage to fiber structures of functional clothes.

2. Description of the Related Art

Generally, a washing machine (normally, a drum washing machine) includes a water tub in which water (wash water or rinse water) is received, a drum rotatably mounted in the water tub, in which laundry fabric (hereinafter, referred to as fabric) is received, and a motor to generate drive force required to rotate the drum. The washing machine washes the fabric received in the drum via an action by which the fabric repeatedly rises along an inner wall of the drum and falls during rotation of the cylindrical drum.

The washing machine performs a series of operations, such as, e.g., a washing operation, a rinsing operation, and a dehydrating operation. The washing operation serves to separate contaminants from the fabric using detergent dissolved water (i.e. wash water). The rinsing operation serves to rinse bubbles or residual detergent out of the fabric using water containing no detergent (i.e. rinse water). The dehydrating operation serves to dehydrate the fabric via high speed rotation. Of these operations, more particularly, the washing operation is carried out in such a manner that water and detergent are input into the water tub when a user selects a washing course and thereafter, the detergent dissolved water is directed to the fabric via rotation of the drum, causing the fabric to be washed using falling force.

However, in the case of functional clothes, more particularly, sports clothes, such as, e.g., hiking clothes, ski wear, and golf wear, clothing surface or fiber structures may be substantially influenced by mechanical force. Therefore, to wash functional clothes with high performance, it may be necessary to effectively remove sweat, contaminants, etc. while maintaining the surface or fiber structures of the functional clothes, i.e. maintaining the functionality of the functional clothes.

Hiking clothes or ski wear have a special function of rapidly discharging sweat generated by the body while preventing invasion of snow, rainwater, etc. To realize this function, materials having coating, adhesion, and other special fiber structures are used. Functions of these materials may easily be destroyed due to surface damage under general washing conditions and alternatively, may exhibit malfunction as pores thereof are blocked by sweat, contaminants (dirt), etc. when repeatedly worn without washing.

Accordingly, without proper care functional clothes gradually become unsuitable for their intended purpose. Therefore, there is a need for a washing course suitable for functional clothes.

Recently developed washing machines have a washing course to wash functional clothes, such as sports clothes, outdoor clothes, etc. However, most of the recent washing machines only wash functional clothes by using mechanical force that is approximately half of a standard course and a delicate course to attempt to minimize damage to clothes. This has substantial drawbacks since maintaining the washing performance may cause deterioration in the functionality of the functional clothes, whereas maintaining the functionality of the functional clothes may result in deterioration of washing performance. Accordingly, there is a need for a control method to satisfy both the washing performance while maintaining functionality of the functional clothes.

SUMMARY

Therefore, it is an aspect to provide a washing machine and a control method thereof to achieve washing performance using bubble washing without damage to the surface or fiber structures of functional clothes.

In accordance with one aspect, a control method of a washing machine having a drum to receive clothes therein and a motor to rotate the drum includes determining whether a washing course of functional clothes is selected, generating bubbles of detergent dissolved water to apply the bubbles to the clothes, and raising a drive operation rate of the motor stepwise to wash the clothes to which the bubbles have been applied.

The functional clothes may include hiking clothes, ski wear, or golf wear.

The generation of the bubbles may include preparing the detergent dissolved water by supplying the water and detergent into a water tub, heating the detergent dissolved water to a preset temperature, and ejecting air droplets into the heated detergent dissolved water, so as to generate the bubbles.

The preset temperature may be set to 30° C. or less, so as not to damage the functional clothes.

The stepwise raising of the drive operation rate of the motor may include driving the motor at a first operation rate to prevent the clothes from clumping while soaking the clothes, and driving the motor at a second operation rate higher than the first operation rate to wash the clothes using mechanical force.

The first operation rate may be 2 seconds On/38 seconds Off, and the second operation rate may be 4 seconds On/58 seconds Off.

A total operation time of the motor when the motor is operated at the first operation rate and the second operation rate may be within a second time.

The second time may be approximately 6 minutes.

The control method may further include performing a wetting operation to cause the clothes to adsorb the water by driving the motor at a period of a first time or less prior to the generation of the bubbles when the washing course of the functional clothes is determined.

A drive period of the motor may be the drive operation rate of the motor as the sum of a motor On time and a motor Off time, and the first time is approximately 10 seconds.

The motor On time of the drive period of the motor may be 4 seconds or less.

The control method may further include rotating the drum forward and reverse for a predetermined time after final dehydration, to remove the water remaining on a surface of the clothes.

The control method may further include, when the washing course of the functional clothes is determined, guiding a user to input a predetermined weight or less of the clothes before supply of the water.

The control method may further include, when the washing course of the functional clothes is determined, controlling supply of the water to a preset amount or less without sensing a weight of the clothes.

In accordance with another aspect, a washing machine includes a water tub, a water supply device to supply water into the water tub, a detergent supply device to supply detergent, a circulating device to circulate the water supplied into the water tub, a drum mounted in the water tub to receive clothes therein, a motor to rotate the drum, and a control unit to control the water supply device and the detergent supply device so that the water and the detergent are supplied into the water tub, bubbles of detergent dissolved water are generated, and washing of functional clothes is performed using the bubbles by varying a drive operation rate of the motor stepwise for a washing period.

The control unit may control the motor at a drive period of a first time or less to cause the clothes to adsorb the water prior to performing the washing of the functional clothes using the bubbles.

The circulating device may include a circulating pipe to circulate the detergent dissolved water in the water tub, and an air guidance pipe to introduce air into the circulating pipe, and the control unit may generate the bubbles using the introduced air while circulating the detergent dissolved water present in a bottom region of the water tub using the circulating device.

The control unit may perform a first washing operation by driving the motor at a first operation rate to prevent the clothes from clumping, and a second washing operation by driving the motor at an operation rate higher than the first operation rate to wash the clothes to which the bubbles have been applied using raised mechanical force.

The control unit may limit a motor On time of the drive operation rate of the motor within a second time.

The control unit may control the drum to rotate forward and reverse for a predetermined time, to remove water remaining on a surface of the clothes after final dehydration.

The control unit may guide a weight of the clothes to a user, and may control the water supply device to supply the water to a preset amount or less.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiment, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

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

As shown inFIG. 1, the washing machine according to the embodiment includes a body10, a drum type water tub11mounted in the body10to receive water (wash water or rinse water) therein, and a cylindrical drum12rotatably mounted in the water tub11, the cylindrical drum12having a plurality of holes13.

A motor16as a drive device is mounted to a rear outer surface of the water tub11and serves to rotate a rotating shaft15connected to the drum12, to enable performance of washing, rinsing, and dehydrating operations. A washing heater17and a water level sensor18are mounted in a bottom region of the water tub11. The washing heater17serves to heat the water (i.e. detergent dissolved water) received in the water tub11. The water level sensor18serves to sense the amount of water (water level) received in the water tub11by detecting a variable frequency depending on the water level.

The water level sensor18controls a wash water level to prevent fabric input into the drum12from being completely wetted by the detergent dissolved water. The wash water level is a water level suitable to generate bubbles (hereinafter, referred to as a bubble generation water level) and corresponds to a level of the detergent dissolved water having a height of 5 cm or less from a surface of the drum12. If the detergent dissolved water supplied for bubble washing reaches the bubble generation water level, the supply of water (wash water) is stopped to prevent the detergent dissolved water from entering the drum12.

A door19having an entrance19ais coupled to a front surface of the body10to put fabric into the drum12or take the fabric out of the drum12. A detergent supply device20to supply detergent and a water supply device30to supply water (wash water or rinse water) are mounted above the water tub11.

The interior of the detergent supply device20is divided into a plurality of spaces. To allow a user to easily input detergent and rinse agent into the respective spaces, the detergent supply device20is positioned toward the front surface of the body10.

The water supply device30includes a first water supply pipe32, a second water supply pipe33, a water supply valve34, and a water supply nozzle35. The first water supply pipe32connects the detergent supply device20to an external water supply pipe31to supply water (wash water or rinse water) into the water tub11. The second water supply pipe33connects the detergent supply device20to the water tub11. The water supply valve34is installed on a portion of the first water supply pipe32to control the supply of water. The water supply nozzle35is installed at an exit of the second water supply pipe33. With this configuration, the water is supplied into the water tub11by way of the detergent supply device20, allowing the detergent received in the detergent supply device20to be supplied into the water tub11together with the water.

A circulating device50and a drain device60are mounted below the water tub11symmetrically about a pump case40. The circulating device50serves to circulate the water in the water tub11, and the drain device60serves to drain the water from the water tub11. A connection hose41is interposed between the water tub11and the pump case40to guide the water from the water tub11to the pump case40.

The circulating device50includes a circulating pump51, a circulating pipe52, a circulating nozzle53, an air inlet hole54, and an air guidance pipe55. The circulating pump51serves to reintroduce the water, guided into the pump case40, into the water tub11. The circulating pipe52is installed at an exit side of the circulating pump51to circulate the water. The circulating nozzle53is installed at an exit of the circulating pipe52to eject the water into the bottom region of the water tub11. The air inlet hole54is perforated in the circulating nozzle53to introduce air into the circulating nozzle53, the air being used to generate bubbles in the water (i.e. the detergent dissolved water) supplied into the bottom region of the water tub11. The air guidance pipe55has an air suction hole56to suction the interior air of the drum12, the air guidance pipe55serving to guide the suctioned air to the air inlet hole54.

The circulating pipe52is connected at one end thereof to the circulating pump51and at the other end thereof to the water tub11. Upon operation of the circulating pump51, the water received in the water tub11is guided into the pump case40through the connection hose41and then, the water guided into the pump case40is reintroduced into the water tub11through the circulating pipe52, resulting in circulation of the water. In this case, to allow the circulating water to be smoothly supplied into the bottom region of the water tub11, the circulating pipe52is connected to the water tub11at the lowest position of the water tub11.

The circulating nozzle53is a venturi tube to reduce the pressure of the circulating water, causing the air suctioned through the air suction hole56to be naturally introduced into the circulating nozzle53through the air guidance pipe55and the air inlet hole54. This air introduction allows the detergent contained in the water to be agglomerated without a separate air supply device, enabling generation of bubbles.

The drain device60includes a drain pump61to drain the water guided into the pump case40to the outside, and a drain pipe62installed at an exit side of the drain pump61to drain the water.

The circulating device50according to the embodiment circulates the water of the water tub11to generate bubbles. Hereinafter, a bubble generating process will be described in more detail with reference toFIGS. 2 to 6.

FIGS. 2 to 6are views illustrating generation of bubbles in the washing machine according to the embodiment.

InFIG. 2, as the water supplied through the water supply valve34is directed to the bottom region of the water tub11together with the detergent by way of the detergent supply device20, the resulting detergent dissolved water begins to be introduced into a space between the water tub11and the drum12until the detergent dissolved water reaches the bubble generation water level (e.g., a height of 5 cm or less from the surface of the drum12).

InFIG. 3, the circulating pump50is operated following the supply of the detergent dissolved water, causing the detergent dissolved water discharged from the circulating pump51to be introduced into the circulating nozzle53through the circulating pipe52. The detergent dissolved water is reduced in pressure while passing through the circulating nozzle53in the form of a venturi tube, resulting in expansion of a circulating flow path. This expanded circulating flow path allows the interior air of the drum12to be introduced into the circulating nozzle53through the air inlet hole54. The air introduced into the circulating nozzle53is ejected into the space between the water tub11and the drum12, creating air droplets in the detergent dissolved water supplied into the space between the water tub11and the drum12.

InFIG. 4, the air droplets created in the space between the water tub11and the drum12float up to the detergent dissolved water surface between the water tub11and the drum12, thereby forming bubbles to move upward from the space between the water tub11and the drum12. Then, the bubbles enter the drum12through the holes13perforated in the drum12and are dispersed in the drum12. Here, the resulting bubbles are obtained via combination of the detergent and the air droplets. When the bubbles generated between the water tub11and the drum12enter the interior of the drum12, the bubbles may pass through an opening perforated in a rear surface of the drum12, or may pass through a peripheral surface as well as the rear surface of the drum12.

InFIG. 5, the bubbles generated via combination of the detergent and the air droplets begin to rise in the interior of the drum12while accumulating on the detergent dissolved water surface, and after a predetermined time (approximately, 3 minutes) passes, are dispersed throughout the interior of the drum12, causing the level of the bubbles to rise. As the level of the bubbles rises, the bubbles act to cover the fabric input into the drum12, causing the high density detergent present on surfaces of the bubbles to be adsorbed into the fabric. Once the generation of the bubbles is stabilized, the level of the detergent dissolved water drops below the surface of the drum12, i.e. to a height in the space between the water tub11and the drum12.

InFIG. 6, when the level of the bubbles reaches a wash water level at which the fabric input into the drum12is sufficiently wet, the drum12is rotated to cause the high density detergent present on the surfaces of the bubbles to be adsorbed into the fabric, allowing the fabric input into the drum12to be washed using the bubbles.

FIG. 7is a control block diagram of the washing machine according to the embodiment. There is illustrated an input unit70, a control unit72, a drive unit74, and a display unit76.

The input unit70inputs operational information, such as a washing course selected by the user (e.g., a standard course or a functional clothes washing course), dehydration RPM, addition of rinsing, etc., to the control unit72.

The control unit72is a microcomputer to control general operations of the washing machine, such as washing, rinsing, dehydration, etc., according to the operational information input from the input unit70. With relation to the functional clothes washing course, to provide an algorithm that may achieve washing performance using bubbles even while substantially preventing the clothes from being damaged by mechanical force, the control unit72stores motor RPM, motor drive operation rate (motor On/Off time), bubble generating operation rate (circulating pump On/Off time), and wash time.

Accordingly, upon washing of functional clothes using bubbles, the control unit72controls the motor RPM, motor drive operation rate, and bubble generating operation rate, thereby controlling operation of the motor16and the circulating pump51to realize an effective washing operation.

The drive unit74drives the motor16, washing heater17, water supply valve34, circulating pump51, drain pump61, etc. according to a drive control signal of the control unit72.

The display unit76displays operating conditions of the washing machine according to a display control signal of the control unit72.

Hereinafter, an operating sequence and effects of the washing machine having the above described configuration and a control method of the washing machine will be described.

FIG. 8is a flow chart illustrating a control sequence for washing of functional clothes using bubbles in the washing machine according to the embodiment. This provides a control method to achieve washing performance while maintaining the functionality of functional clothes.

If the user selects the functional clothes washing course after putting functional clothes, such as sports clothes, outdoor clothes, or the like, into the drum12, information of the washing course selected by the user is input to the control unit72via the input unit70.

The control unit72determines based on the washing course information input from the input unit70whether or not the washing course selected by the user is the functional clothes washing course (100). If the selected washing course is not the functional clothes washing course, a general washing course is performed in the same manner as the prior art (101).

If it is determined from the operation100that the washing course selected by the user is the functional clothes washing course, the control unit72omits a weight sensing operation to reduce damage to the clothes, and guides input of clothes of 3 Kg or less via the display unit76(102). Thereafter, the control unit72sets the amount of wash water to a predetermined value (approximately, 15 liters) or less (103).

The reason why setting the amount of wash water to the predetermined value or less is because it has been experimentally found that the amount of wash water may cause damage to functional clothes.

Thereafter, the control unit72controls the water supply valve34to supply the detergent dissolved water required for bubble generation, allowing water (i.e. wash water) to be supplied into the water tub11by way of the first water supply pipe32and the detergent supply device20. In this case, the detergent in the detergent supply device20is dissolved in the supplied water (wash water), thereby being introduced into the water tub11through the second water supply pipe33and the water supply nozzle35together with the water (wash water). Thereby, as shown inFIG. 2, the resulting detergent dissolved water is supplied below the water tub11(i.e. into the space between the water tub11and the drum12) (104).

Once the detergent dissolved water is supplied, the control unit72performs a wetting operation to wet the functional clothes received in the drum12prior to performing a main washing operation using bubbles (106).

During the wetting operation, a drive period of the motor16is controlled to a predetermined first time (approximately, 10 seconds) or less so as to frequently rotate the drum12, allowing the functional clothes to frequently contact the detergent dissolved water of a low density or the water (although the functional clothes are actually smeared with the detergent dissolved water, the detergent is not sufficiently dissolved yet and therefore, the detergent dissolved water in contact with the clothes may be naturally referred to as the water). Since main components of the functional clothes are polyester and nylon having characteristics of low water absorption, to facilitate initial wetting for realization of washing performance, the functional clothes may need to frequently come into contact with the water for a short time to uniformly adsorb the water throughout the clothes surface. For example, a drive period of the motor16during the wetting operation is set to a drive operation rate of 2″/5″ (2 seconds On/5 seconds Off), 3″/4″ (3 seconds On/4 seconds Off), and 4″/3″ (4 seconds On/3 seconds Off). That is, a total drive period of On time and Off time of the motor16is programmed so as not to exceed a predetermined time (approximately, 10 seconds). Here, if the On time of the motor16is set to be long, damage to clothes by mechanical friction may occur and therefore, the On time of the motor16may be set to 4″ or less.

Accordingly, the motor16is frequently rotated by a short drive interval (the sum of On time and Off time) during a performance time of the wetting operation (approximately, 5 minutes), allowing the functional clothes to frequently come into contact with the water.

Thereafter, the control unit72operates the circulating pump51after supply of the detergent dissolved water, generating bubbles to dampen mechanical force that will be generated in a following main washing operation and allowing the bubbles to be applied to the functional clothes that are substantially stationary (108).

During the bubble application, the bubbles are generated according to a preset bubble generating operation rate (3 minutes On/30 seconds Off) after heating of the detergent dissolved water, to apply the detergent dissolved water to be applied to the functional clothes. This may enhance washing performance in the following main washing operation. The generation of the bubbles via operation of the circulating pump51is as shown inFIGS. 2 to 6.

If the circulating pump51is operated, the water received in the water tub11is guided into the pump case40through the connection hose41and in turn, the water guided into the pump case40is reintroduced into the bottom region of the water tub11through the circulating pipe52, enabling circulation of the water. In this case, when the circulating water passes through the circulating nozzle53after passing through the circulating pipe52, the pressure of the water is suddenly reduced, causing air to be naturally introduced into the circulating nozzle53through the air inlet hole54. Thereby, air droplets are ejected into the water (the detergent dissolved water) reintroduced into the bottom region of the water tub11, forming bubbles on the detergent dissolved water surface via combination with the detergent.

The bubbles generated via combination of the detergent and the air droplets begin to rise in the interior of the drum12and are dispersed throughout the interior of the drum12after the predetermined time (approximately, 3 minutes) passes, thereby allowing the detergent dissolved water to be effectively transmitted to the functional clothes located in the drum12.

After completion of the wetting operation and the bubble application and prior to initiating the main washing operation, the control unit72operates the washing heater17to heat the water to a preset temperature (not exceeding 30° C.) (110). In this case, the reason why the preset temperature does not exceed 30° C. is to realize an effective temperature to achieve washing performance without damage to the surface of the functional clothes.

After the bubbles are applied to the surface of the functional clothes, to perform the main washing operation using the bubbles, the control unit72performs a first main washing operation by rotating the drum12at a preset motor RPM (approximately, 40 RPM or less) and a preset first drive operation rate (for example, 2 seconds On/38 seconds Off) (112). The first main washing operation serves to loosen the functional clothes to allow mechanical force to be uniformly applied to the functional clothes.

The first main washing operation may have the effect of not only uniformly dispersing the clothes so as not to clump, but also substantially soaking the clothes.

Subsequently, the control unit72performs a second main washing operation by rotating the drum12at a second drive operation rate of the motor16(for example, 4 seconds On/58 seconds Off) higher than the drive operation rate in the first main washing operation to raise the mechanical force stepwise (114). The second main washing operation serves to remove sweat, contaminants, or the like from the functional clothes while mixing the detergent dissolved water of a high density on the surfaces of the bubbles with the functional clothes. In this case, the bubbles may act to dampen falling force caused upon rotation of the drum12and frictional force of the functional clothes, thereby preventing frictional damage to the functional clothes.

The control unit72limits a total operation time of the motor16within a second time (approximately, 6 minutes) according to a drive operation rate of the motor16for a total washing time (approximately, 30 minutes) of the first main washing operation and the second main washing operation. If the washing time exceeds the above time, the water repellency as one of the functionalities of the functional clothes may be deteriorated to a second grade when a washing operation is repeated 30 times or more. Therefore, the functional clothes may have properties not to satisfying the regulations of the Korean Consumer Agency and standards of certification organizations.

A valuation method and valuation basis per water repellency grade are shown inFIG. 9.

FIG. 9is a table illustrating a valuation basis per water repellency grade. The lower the water repellency grade, the more serious the deterioration in the functions of the functional clothes.

inFIG. 9, water repellency of a fifth grade represents that a clothes surface has no adhesion and wetting, water repellency of a fourth grade represents that a clothes surface has a little adhesion and wetting, water repellency of a third grade represents that only a region of a clothes surface in contact with water becomes wet, water repellency of a second grade represents that an entire clothes surface is partially wet, and water repellency of a first grade represents that a clothes surface and an opposite side thereof are completely wet.

Referring back toFIG. 8, subsequently, the control unit72determines whether it is a predetermined time (approximately, 3 minutes) until the washing time of the functional clothes using bubbles is completed (116). If the predetermined time has not yet been reached, the control unit72returns to the operation114to perform the following operations. If the predetermined time has been reached, the control unit72stops the circulating pump51to stop the generation of bubbles (118).

Thereafter, if the washing operation of the functional clothes using bubbles is completed, the control unit72performs dehydration by rotating the motor16at 600 RPM for 4 minutes or more to achieve dehydration performance while reducing damage to the functional clothes (120).

After completion of the dehydration, the control unit72performs a rinsing operation a preset number of rinsing times (approximately, 3 times), to achieve rinsing performance (122). In this case, similar to the dehydration after washing, dehydration during rinsing is performed by rotating the motor16at 600 RPM for 4 minutes or more to achieve dehydration performance while reducing damage to the functional clothes. However, intermediate dehydration before the last rinsing is performed only to sweep away water from the clothes surface by rotating the motor16at 100 RPM only for 1 minute to further reduce damage to the clothes.

After the rinsing operation is completed, similar to the dehydration after washing and the dehydration during rinsing, the control unit72performs final dehydration by rotating the motor16at 600 RPM for 4 minutes or more to achieve dehydration performance while reducing damage to the clothes (124).

Meanwhile, the control unit72performs unbalance control upon the dehydration after washing, upon the dehydration during rinsing, and upon the final dehydration. The unbalance control is applicable in any available conventional method.

After completion of the final dehydration, the control unit72rotates the drum12forward and reverse at a preset motor RPM (approximately 70 RPM, at which the clothes become adhered to a wall surface of the drum) and a drive operation rate (for example, 5 seconds On/10 seconds Off) for a predetermined time (approximately, 1-2 minutes), so as to remove water remaining on the surface of the functional clothes and thereafter, ends the washing of the functional clothes (126).

Although the embodiment exemplifies that the circulating pump51and the drain pump61are symmetrically arranged at opposite sides of the pump case40, the embodiment of the present invention is not limited thereto, and the circulating pump51and the drain pump61may be arranged in parallel in a front rear region of the body10. In addition, the embodiment of the present invention is applicable to any configuration to achieve circulation and drainage of water.

As is apparent from the above description, bubble washing may effectively remove sweat, contaminants, etc. without damage to the surface or fiber structures of functional clothes, achieving washing performance of a washing machine. Further, by performing a rinsing operation at the sufficient number of rinsing times, rinsing performance sufficient to rinse residual detergent out of a surface of the clothes as well as dehydration performance with reduced damage to the clothes may be accomplished, resulting in functionality of the clothes.