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(11) | EP 4 123 077 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 153(4) EPC |
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| (54) | CLOTHING TREATMENT APPARATUS |
| (57) A clothing treatment apparatus according to one embodiment of the present disclosure
comprises: a drum for accommodating laundry; a motor for driving the drum; a drying
unit for drying the laundry by heating the drum; and a current detection unit for
detecting a current flowing through the motor, wherein drying of the laundry can end
on the basis of a first current value detected by the current detection unit when
the motor drives the drum at a first revolutions per minute and a second current value
detected by the current detection unit when the motor drives the drum at a second
revolutions per minute that are greater than the first revolutions per minute. |
Technical Field
Background Art
[0002] A clothing treatment apparatus may include a washing machine for washing laundry, a dryer for drying laundry or wet clothing, an apparatus for refreshing clothing, etc. The washing machine may be a washer-dryer combo having a drying function.
[0003] For instance, the washing machine includes a tub (outer case) that stores washing water and a drum (inner case) that is rotatably provided in the tub. Laundry is put into the drum, and is washed by detergent and washing water as the drum rotates. The dryer dries the laundry by rotating the drum and applying heat the laundry in the drum.
[0004] Generally, drying may be performed by supplying high-temperature hot air into the drum to heat an object and thereby evaporate water. An exhaust-type dryer for discharging humid air to the outside of the washing machine and a circulation-type dryer for condensing water from humid air and supplying the water back to the drum may be provided.
[0005] Meanwhile, the clothing treatment apparatus may be provided with a heater. The heater is commonly operated while being submerged in water in the tub to directly heat water. Since such a type of heater should be operated while being always submerged in water for safety reasons, it may be used to heat water in the tub, but it is not suitable for heating air in the drum in a state where there is no water in the tub, or for heating wet laundry before spin-drying. Recently, a clothing treatment apparatus configured such that a drum is heated by an induction heating system is being used.
[0006] As drying is performed, the overall temperature rises. It is possible to detect dryness using the temperature characteristics of a lower temperature sensor mounted on a lower side of the tub. As the drying process proceeds, the temperature of the lower temperature sensor may be changed as follows.
[0007] That is, in initial and intermediate stages of the drying, the amount of heat for heating wet steam may be the same as the amount of heat for cooling condensate. However, in a late stage of the drying, the amount of heat for cooling condensate may be relatively larger than the amount of heat for heating dry air. Thus, the temperature in the tub may be decreased.
[0008] However, in the late stage of the drying, the wet steam in the tub is changed into dry air. At this time, since the amount of heat for cooling condensate on the rear of the tub becomes much larger than the amount of heat for heating the dry air, a value detected by the lower temperature sensor may be decreased with the lapse of time.
[0009] When the dryness is detected using the change in temperature detected by the upper temperature sensor and the lower temperature sensor and the change in difference (Delta T) between these temperatures, the temperature difference value (Delta T) may vary depending on the temperature condition in the tub such as intermittent drying or continuous drying or outside-air temperature, so that the dryness cannot be accurately detected.
[0010] Further, when the heating output of a heater greatly fluctuates, the overall system temperature (e.g. temperature in the tub) also fluctuates greatly, so that the probability of false detection in dryness may increase. Further, depending on the temperature of the condensate, the false detection in dryness may occur.
[0011] As described above, when the dryness is detected using the change in temperature detected by the upper temperature sensor and the lower temperature sensor and the change in difference (Delta T) between these temperatures, it is highly likely to change depending on external environment and system environment. Therefore, the accuracy of dryness detection may be deteriorated, and there is a possibility of false detection.
SUMMARY
[0013] An objective of the present disclosure is to provide a clothing treatment apparatus capable of precisely detecting dryness in a drying operation, such as a dryer, a washing machine, a washer-dryer combo, or a clothing refresh apparatus.
[0014] Further, an objective of the present disclosure is to provide a clothing treatment apparatus capable of effectively preventing the overheating of clothing.
[0015] Further, an objective of the present disclosure is to provide a dryness detection method that is relatively resistant to external environment.
[0016] Further, an objective of the present disclosure is to provide a clothing treatment apparatus capable of minimizing the effect of internal mechanical change such as a motor when determining dryness.
[0017] Further, an objective of the present disclosure is to provide a clothing treatment apparatus capable of precisely detecting a motor current.
[0018] In a clothing treatment apparatus, as the drying of laundry (clothing) is performed, the moisture content of a dried object is reduced, so that a weight is reduced. At this time, if the weight of the dried object is reduced, torque for rotating the drum may be reduced, so that the intensity of motor current may be reduced compared to the initial stage of drying.
[0019] In the process of drying laundry, the drum containing the laundry may be driven. For instance, the drum may be tumbling driven. In this case, wet laundry may have a relatively high current difference between the driving of the drum at high rpm and the driving of the drum at relatively low rpm. For example, if a water-balloon phenomenon occurs in the laundry, there may be a large difference in driving current when the laundry in which the water-balloon phenomenon has occurred is driven at high rpm and when the laundry is driven at low rpm. In contrast, dried laundry may have a relatively low current difference between the driving of the drum at high rpm and the driving of the drum at relatively low rpm.
[0020] A clothing treatment apparatus according to an aspect of the present disclosure may determine the dryness of clothing on the bases of motor current during a drying operation.
[0021] A clothing treatment apparatus according to an aspect of the present disclosure may perform a drying operation while changing the rpm of a drum, and may determine the dryness of clothing on the basis of motor current when the drum is driven at different rpm.
[0022] A clothing treatment apparatus according to an aspect of the present disclosure may determine the dryness of clothing on the basis of a current value when a drum is driven at first rpm and a current value when the drum is driven the second rpm greater than the first rpm.
[0023] A clothing treatment apparatus according to an aspect of the present disclosure may include a drum for accommodating laundry; a motor for driving the drum; a drying unit for heating the drum to dry the laundry; and a current detection unit for detecting current flowing through the motor, and may end the drying of the laundry on the basis of a first current value detected by the current detection unit when the motor drives the drum at first rpm and a second current value detected by the current detection unit when the motor drives the drum at second rpm greater than the first rpm.
[0024] The first current value may be a first current average value obtained by averaging currents sensed by the current detection unit in a section where the drum is driven at the first revolutions per minute, and the second current value may be a second current average value obtained by averaging currents sensed by the current detection unit in a section where the drum is driven at the second revolutions per minute.
[0025] The drying may end when a ratio of the first current value to the second current value is less than a predetermined reference value.
[0026] During the drying, the operation of driving the drum at the first revolutions per minute and the operation of driving the drum at the second revolutions per minute may be repeatedly performed.
[0027] The clothing treatment apparatus may further include a fan rotating in at least a part of the section during the drying, and the fan may be driven at a speed less than a predetermined speed or be stopped, when the current detection unit detects current flowing through the motor.
[0028] At least one of the first revolutions per minute and the second revolutions per minute may be smaller than revolutions per minute at which the laundry accommodated in the drum is attached to the drum and is rotated.
[0029] The first revolutions per minute may be 60 rpm or less, and the second revolutions per minute may be 100 rpm or more.
[0030] The clothing treatment apparatus may further include a memory storing the first current value and the second current value.
[0033] The induction heater may be spaced apart from the drum. The induction heater may be installed in the tub. The induction heater may be secured to the tub. In the clothing treatment apparatus such as a dryer having no tub, the induction heater may be disposed in or on an inner wall of a case.
[0034] In the clothing treatment apparatus having no tub such as the dryer, the induction heater may be disposed on the upper side, lower side, left side or right side of the drum in a case to be spaced apart from the drum.
[0036] The induction heater may generate a magnetic field. The induction heater heats the drum using a magnetic field.
[0037] The motor may stop the drum for a predetermined time, after the drum is rotated at the first rpm and the drum is rotated at the second rpm.
[0038] The motor may rotate the drum at the second rpm for a time longer than a time when the drum is rotated at the first rpm.
[0040] The clothing treatment apparatus may further include a control unit that controls the driving of the motor.
[0041] A clothing treatment apparatus according to an aspect of the present disclosure may end the drying of the laundry on the basis of at least one of a first current value detected by the current detection unit when the motor drives the drum at first rpm and a second current value detected by the current detection unit when the motor drives the drum at second rpm greater than the first rpm.
[0042] To be more specific, the first current value may be a first current average value obtained by averaging currents sensed by the current detection unit in a section where the drum is driven at the first revolutions per minute, and the second current value may be a second current average value obtained by averaging currents sensed by the current detection unit in a section where the drum is driven at the second revolutions per minute. The drying may end when at least one of ratios of the first current average value and the second current average value is less than a predetermined reference value.
[0043] Alternatively, the drying operation may be controlled on the basis of at least one of a maximum value, a minimum value, and a median value of motor current detected in a section where the drum is driven at the first or second rpm.
[0044] According to an aspect of the present disclosure, it is possible to check the current weight level of laundry, by performing a first storing step where a drum is driven at first revolutions per minute and a first current average value is stored as the drum is driven; a second storing step where the drum is driven at second revolutions per minute that are greater than the first revolutions per minute and a second current average value is stored as the drum is driven; and a step of calculating a ratio of the first current average value to the second current average value. Therefore, the drying degree of laundry can be determined through these steps.
[0045] A control method of a clothing treatment apparatus according to an aspect of the present disclosure may include a step of drying laundry; a first storing step where a drum is driven at first revolutions per minute and a first current average value is stored as the drum is driven; a second storing step where the drum is driven at second revolutions per minute that are greater than the first revolutions per minute and a second current average value is stored as the drum is driven; a step of calculating a ratio of the first current average value to the second current average value; and a step of determining whether laundry has been dried using the ratio.
[0046] Further, when it is determined in the determining step that the laundry has not been dried, the method may further include a step of performing a drying operation.
[0047] Further, after the step of performing the drying operation, the first storing step, the second storing step, the calculation step, and the determining step may be re-performed.
[0048] Further, the first storing step, the second storing step, the calculation step, and the determining step may be re-performed at regular time intervals.
[0049] Further, when it is determined in the determining step that the drying of the laundry is completed, the method may further include a step of performing additional drying and ending drying.
[0050] Further, at least one of the first revolutions per minute and the second revolutions per minute may be smaller than revolutions per minute at which the laundry accommodated in the drum is attached to the drum and is rotated.
[0051] Further, the step of determining whether the drying is completed may determine that the drying is completed when the ratio is smaller than a specific value.
[0054] A clothing treatment apparatus according to an aspect of the present disclosure may include a tub accommodating washing water; a drum rotatably provided in the tub and accommodating laundry; a motor for driving the drum; a drying unit for drying the laundry; and a control unit for controlling the driving of the motor. The control unit may drive the drum at first revolutions per minute, store a first current average value by the driving of the drum, drive the drum at second revolutions per minute greater than the first revolutions per minute, store a second current average value by the driving of the drum, calculate a ratio of the first current average value to the second current average value, and determine whether the drying of laundry is completed with the ratio.
[0055] Further, when it is determined that the drying of the laundry is not completed, the control unit may perform the drying operation.
[0056] Further, when a predetermine time has passed after the drying operation is performed, the control unit may re-perform the processes of storing the first current average value, storing the second current average value, calculating the ratio of the first current average value to the second current average value, and determining whether the drying is completed with the ratio.
[0057] Further, the control unit may re-perform, at regular time intervals, the processes of storing the first current average value, storing the second current average value, calculating a ratio of the first current average value to the second current average value, and determining whether the drying is completed with the ratio.
[0058] Further, when it is determined that the drying of the laundry is completed, the control unit may perform additional drying and then complete drying.
[0059] Further, at least one of the first revolutions per minute and the second revolutions per minute may be smaller than revolutions per minute at which the laundry accommodated in the drum is attached to the drum and is rotated.
[Advantageous Effects]
[0060] According to at least one of embodiments of the present disclosure, dryness can be precisely detected using motor current.
[0061] According to at least one of embodiments of the present disclosure, the overheating of clothing can be prevented and clothing can be effectively dried using an induction heater.
[0062] According to at least one of embodiments of the present disclosure, it is advantageous in that there is almost no change due to external factors such as external environment, and dryness is determined using only motor current, so that it is resistant to external environment. Therefore, dryness can be determined without being affected by a change in external environment.
[0063] Further, according to at least one of embodiments of the present disclosure, since dryness is determined using the ratio of current when a drum is driven at high revolutions per minute and low revolutions per minute, the influence of internal mechanical changes such as a motor can be minimized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064]
FIG 1 is a perspective view showing the outside of a clothing treatment apparatus according to an embodiment of the present disclosure.
FIG 2 is a sectional view showing the inside of the clothing treatment apparatus according to an embodiment of the present disclosure.
FIG 3 is a block diagram showing the control configuration of the clothing treatment apparatus according to an embodiment of the present disclosure.
FIGS. 4 to 6 are diagrams showing the operation state during drum stop, tumbling driving, and filtration driving, respectively.
FIG 7 is a schematic view of the clothing treatment apparatus according to an embodiment of the present disclosure.
FIGS. 8 and 9 are graphs for explaining an example of determining a drying end time.
FIG 10 is a flowchart showing a control method of a clothing treatment apparatus according to an embodiment of the present disclosure.
FIG 11 is a graph showing a drying operation (drying motion) by the control method of the clothing processing treatment according to an embodiment of the present disclosure.
FIG 12 is a graph showing a change in current value by the control method of the clothing processing treatment according to an embodiment of the present disclosure.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0065] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The same reference numerals are used throughout the drawings to designate the same or similar components, and a duplicated description thereof will be omitted.
[0066] The suffixes "module" and "unit" for components used in the following description are given or used in consideration of only the ease of describing the specification, and do not have distinct meanings or roles.
[0067] When it is determined that the detailed description of the known art related to an embodiment disclosed in the specification may be obscure the gist of the embodiment, the detailed description thereof will be omitted. Further, it is to be understood that the accompanying drawings are merely for making those skilled in the art easily understand the embodiment disclosed herein, the technical spirit of the present disclosure is not limited to the accompanying drawings, and the present disclosure covers all alternatives, modifications, and equivalents that fall within the spirit and scope of the present disclosure.
[0068] Herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.
[0069] Furthermore, although each drawing is described for the convenience of description, it is apparent to those skilled in the art that other embodiments may be implemented by combining at least two or more drawings without departing from the scope of the present invention.
[0070] Although the terms "first", "second", etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another component.
[0071] It should be understood that when a component is referred to as being "coupled" or "connected" to another component, it can be directly coupled or connected to the other component or intervening components may be present therebetween. In contrast, it should be understood that when a component is referred to as being "directly coupled" or "directly connected" to another component, there are no intervening components present.
[0072] Further, it should be understood that, when a first component such as a layer, a region or a module is referred to as being "on" a second component, the first component may be not only directly on the second component but a third component may be interposed between them.
[0073] Hereinafter, a clothing treatment apparatus and a control method thereof according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. Hereinafter, a washing machine will be described as a representative example of the clothing treatment apparatus according to the present disclosure. However, the clothing treatment apparatus of the present disclosure is not limited thereto.
[0074] Hereinafter, the clothing treatment apparatus according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2.
[0075] FIG 1 is a perspective view showing the outside of a washing machine according to an embodiment of the present disclosure. Further, FIG 2 is a sectional view showing the inside of the washing machine according to an embodiment of the present disclosure.
[0076] The washing machine according to an embodiment of the present disclosure may include a drum 30, and a drying unit 70 that heats the drum 30. Such a drying unit may include at least one heater 70. More preferably, the drying unit may include an induction heater 70. The washing machine may further include a cabinet 10 that defines an appearance.
[0077] The washing machine may further include a tub 20 that receives the drum 30. The tub 20 may be provided inside the cabinet 10. The tub 20 may provide a receiving space. The tub 20 may have on a front thereof an opening. The tub 20 may receive washing water. The tub 20 may be provided to receive the drum 30.
[0078] The drum 30 may be rotatably provided inside the tub 20. The drum 30 may be provided in the receiving space of the tub 20. The drum 30 may receive laundry. An opening may be provided in the front of the drum 30. The laundry may be put into the drum 30 through the opening.
[0079] A hole 30h may be formed in the circumferential surface of the drum 30 such that air and washing water communicate between the tub 20 and the drum 30. Hereinafter, the circumferential surface of the drum 30 may also be referred to as the body of the drum 30. The body of the drum 30 may extend in the shape of a cylinder.
[0080] The drum 30 may be formed of a conductor. The body of the drum 30 may be formed of a conductor. The body of the drum 30 may be formed of metal.
[0081] An induction heater or an IH module 70 may heat the drum 30. The induction heater 70 may generate a magnetic field. The induction heater 70 may be provided to heat the drum 30 using the magnetic field.
[0082] The induction heater 70 may be provided on the outer circumference of the tub 20. The induction heater 70 may be provided on the upper portion of the tub 20. The induction heater 70 may be secured to the tub 20. The induction heater 70 may be spaced apart from the drum 30. Here, the induction heater 70 may perform a laundry drying function by heating the drum 30. However, a general heater as well as the induction heater 70 may be provided. That is, various heaters such as a sheath heater or a heater using a heat pump may be provided.
[0083] Each of the tub 20 and the drum 30 may be formed in a cylindrical shape. Thus, the inner circumference and the outer circumference of each of the tub 20 and the drum 30 may be substantially formed in a cylindrical shape.
[0084] On the other hand, the clothing treatment apparatus such as a dryer may not be provided with the tub. The induction heater 70 may be provided in the cabinet. The induction heater 70 may be disposed inside the cabinet or on an inner wall thereof. The induction heater 70 may be spaced apart from the drum 30 and be secured to the cabinet 10.
[0085] FIG 2 illustrates the washing machine configured such that the drum 30 is rotated about a rotating shaft parallel to the ground. Unlike shown in the drawing, the drum 30 and the tub 20 may tilted rearward. The rotating shaft of the drum 30 may pass through the rear surface of the washing machine. That is, a straight line extending along the rotating shaft 42 of the driving unit 40 may pass through the rear surface of the washing machine.
[0086] The washing machine may further include a driving unit 40 that is provided to rotate the drum 30 inside the tub 20. The driving unit 40 may include a motor 41. The motor 41 may include the rotating shaft 42. The rotating shaft 42 may be connected to the drum 30 to rotate the drum 30 inside the tub 20.
[0087] The motor 41 may include a stator and a rotor. The rotor may be connected to the rotating shaft 42.
[0088] The driving unit 40 may include a spider 43. The spider 43 may be configured to connect the drum 30 and the rotating shaft 42 and to uniformly and stably transfer the rotating force of the rotating shaft 42 to the drum 30.
[0089] The spider 43 may be coupled to the drum 30 such that at least a portion thereof is inserted into the rear wall of the drum 30. To this end, the rear wall of the drum 30 may be formed to be recessed into the drum 30. Further, the spider 43 may be coupled to the drum in the form of being further inserted into the drum 30 at the rotation center of the drum 30.
[0090] A lifter 50 may be provided in the drum 30. A plurality of lifters 50 may be provided in the circumferential direction of the drum 30. The lifter 50 may perform the function of stirring laundry. For instance, as the drum 30 rotates, the lifter 50 may lift the laundry upward.
[0091] The laundry moved upward is separated from the lifter 50 by gravity to fall downward. The laundry may be performed by impact force caused by falling. Of course, the stirring of the laundry may enhance drying efficiency. The lifter 50 may be formed to extend from the rear end of the drum 30 to the front end thereof. The laundry may be evenly distributed from front to rear in the drum 30.
[0092] FIG 3 is a block diagram showing the control configuration of the washing machine according to an embodiment of the present disclosure.
[0093] Hereinafter, the control configuration of the washing machine according to an embodiment of the present disclosure will be described in detail with reference to FIG 3.
[0094] The control unit 90 serving as a main processor may be provided to control the operation of the washing machine. The operation of various control configurations that will be described later may be controlled through the control unit 90.
[0095] The motor 41 may drive the drum 30. That is, the motor 41 may be provided to rotate the drum 30. The rotating force of the motor 41 may be directly or indirectly transmitted to the drum 30. For instance, a direct-coupled motor in which the rotating force of the motor 41 is directly transmitted to the drum 30 may be used.
[0096] The driving pattern of the drum 30 may vary depending on the driving pattern of the motor 41. Thus, the control unit 90 may control the driving of the motor 41 to generate various driving operations, such as the tumbling driving, filtration driving, and spin driving of the drum. The driving state of the drum 30 may be referred to as the operation of the drum.
[0097] The tumbling driving (see FIG 5) of the drum 30 may be driving in which laundry in the drum 30 is lifted and then dropped as the drum rotates at about 40 to 46 RPM. That is, the tumbling driving may be referred to as driving in which washing or laundry wetting is performed by mechanical force through the fall of laundry and the friction with the drum. Since this is driving in which laundry is stirred in the drum 30, this is commonly used.
[0098] The filtration driving (see FIG 6) of the drum 30 may be driving in which laundry is in close contact with the inner circumference of the drum 30 inside the drum 30 so that the drum and the laundry are integrally rotated, as the drum rotates at about 100 RPM. Here, the laundry is spread on the inner circumference of the drum 30 and washing water is removed from the laundry.
[0099] The spin driving of the drum 30 may be driving in which washing water is centrifugally dehydrated from laundry as the drum 30 rotates about 800 RPM or more. The spin driving may be performed in a final washing process by a very large centrifugal force, so that all washing processes may be completed.
[0100] Thus, the RPM of the drum is increased in the order of the tumbling driving, the filtration driving, and the spin driving. The spin driving may be referred to as driving of continuously rotating the drum 30 in one direction, and the tumbling driving and the spin driving may be referred to as driving of repeating forward and reverse rotation and stop.
[0101] For washing, the washing water should be supplied from the outside of the washing machine to the inside of the tub. To this end, the washing machine may be provided with a water supply valve 23. The water supply valve may be connected to an external water supply source. When the water supply valve is operated, the washing water may be supplied to the inside of the washing machine.
[0102] If necessary, a plurality of water supply valves 23 may be provided. A cold-water valve 25 for supplying cold water from an external water supply source and a pre-valve 24 connected to a boiler or the like to supply water other than cold water, e.g. hot water may be provided.
[0103] When the temperature of the washing water is set to room temperature (cold water) during washing, the heating of the washing water may not be required. Thus, in this case, water supply may be performed only by the cold-water valve 25. However, when the temperature of the washing water is set to fixed temperature (25°C, 40°C, etc.) rather than room temperature during washing, washing water may be supplied through the pre-valve 24 and the cold-water valve 25. Of course, in the latter case, washing water may be supplied only through the cold-water valve 25.
[0104] Meanwhile, the pre-valve 24 and the cold-water valve 25 may be valves for supplying the same cold water. The watery supply through the pre-valve 24 may be the case of supplying water through the inside of the drum to the tub, and the water supply through the cold-water valve 25 may be the case of supplying water to the tub without passing through the inside of the drum. Of course, this may be performed in reverse.
[0105] Further, the pre-valve 24 may be a water supply valve for supplying washing water through a detergent box to the tub, and the cold-water valve 25 may be a water supply valve for directly supplying washing water to the inside of the tub without passing through the detergent box. Of course, this may be performed in reverse.
[0106] Thus, a plurality of water supply valves may be provided according to the temperature of washing water and the water supply course of washing water.
[0107] A water level sensor 26 may be provided to sense the water level of washing water supplied to the inside of the tub. That is, this may be referred to as a sensor for controlling a proper amount of washing water.
[0108] Generally, the water level sensor 26 may often use a frequency sensor that senses a water level through a frequency. This sensor senses the water level using a principle in which the sensed frequency varies depending on the water level. During washing, the water level sensor 26 senses the water level so that water is supplied between an empty water level and a maximum water level. The maximum water level is a heater protection water level as described above, and may be referred to as a water level at which a lower portion of the drum is submerged in the washing water. Generally, water is supplied until the level of the washing water becomes the heater protection water level after laundry fully absorbs the washing water.
[0109] The empty water level in the frequency sensor may be about 25.5 Khz, and the heater protection water level may be about 24.7 Khz. Of course, a specific frequency value may vary depending on the size of a washing machine, the model of the frequency sensor, and external environment. However, the higher the frequency in the frequency sensor, the lower the water level.
[0110] The control unit 90 controls the operation of the water supply valve 23 based on a water level value sensed by the water level sensor 26.
[0111] As an example of the heater, the induction heater (IH) 70 may be a heater that heats the drum 30 by induction. As described above, heaters other than the induction heater may be installed. Hereinafter, the induction heater 70 is described as an example of the heater, but the present invention is not limited thereto.
[0112] If the drum 30 is heated by the induction heater 70, the washing water may be heated. Of course, the washing water as well as the laundry contacting the drum 30 may be directly heated. The laundry absorbing the washing water may be directly heated by the heating method, thus making it possible to increase heating effect. Further, since the diffusion of heat to the surroundings is reduced, heating efficiency is further enhanced.
[0113] When washing, heating through the induction heater 70 may be performed based on temperature data sensed by a washing-water temperature sensor 28. That is, if the temperature of washing water reaches a preset temperature, heating may be completed.
[0114] By the induction heater 70, the drum 30 may be heated to about 160 °C in a short time. For instance, the outer-circumference temperature of the drum 30 may rise to 160 °C in about 3 seconds. Thus, since heat from the drum 30 is transmitted to the washing water and laundry, it may be necessary to prevent the overheating of the drum 30 or the overheating of the induction heater 70.
[0115] In order to prevent the overheating of the drum 30, a drying temperature sensor 29 may be provided. The drying temperature sensor 29 may be provided to directly or indirectly sense the outer-circumference temperature of the drum 30. When it is determined through the drying temperature sensor 29 that the drum 30 is overheated, the control unit 90 stops operating the induction heater 70.
[0116] The washing-water temperature sensor 28 may be mounted on the lower portion of the tub 20 to sense the temperature of the washing water. The drying temperature sensor 29 may be mounted on the upper portion of the tub 20 to sense the outer-circumference temperature of the drum 30. Thus, it is advantageous that both installation positions and sensing targets are different.
[0117] The washing-water temperature sensor 28 may directly sense the temperature of the washing water. The drying temperature sensor 29 may not be in contact with the rotating drum 30 to indirectly sense the temperature of the drum 30. Thus, it is advantageous that the sensing mechanisms or methods thereof are different from each other.
[0118] The washing-water temperature sensor 28 may be provided to sense the temperature of washing water when the drum 30 is stopped. This sensor may control so that the induction heater 70 is not operated when the washing-water temperature reaches a target temperature. The drying temperature sensor 29 may be provided to sense the temperature of the drum 30 when the drum 30 rotates. In particular, this sensor may be provided to sense the temperature when the drum 30 rotates and when the induction heater 70 rotates. Thus, it is advantageous that sensing times thereof are different from each other.
[0119] Such a dual sensor configuration may provide a safe washing machine and a method of controlling the apparatus.
[0120] As the drum 30 is driven, detergent water absorbed by laundry may be gradually discharged to the tub 20, thereby deteriorating washing effect. Thus, a circulation pump 80 for supplying or re-supplying the detergent water to the laundry may be provided.
[0121] The circulation pump 80 may be configured such that a portion of the washing water is pumped out from the bottom of the tub 20, and the washing water is sprayed from the top of the drum 30 to the laundry. The washing effect can be improved by the injection pressure of the washing water, and the washing water (detergent water) may be re-supplied to the laundry so that the laundry always maintains a sufficiently wet state. Therefore, even if the laundry is not immersed in the washing water, effective washing can be performed.
[0122] Washing through the washing machine may be performed through initial water supply, laundry wetting, heating, and a main washing step or section. After the main washing, rinsing and spin-drying may be performed to complete washing. The entire washing process or washing course is automatically performed in the order of a washing operation, a rinsing operation, and a spin-drying operation and then is completed.
[0123] The washing machine according to an embodiment of the present invention may further include a memory (not shown) in which various pieces of data are stored. The memory may store control data for controlling the operation of the washing machine, inputted operation setting data, data on an operation mode, reference data for determining an error, etc.
[0124] Further, data that is calculated, detected or measured during the operation of the washing machine may be stored in the memory.
[0125] The washing machine according to an embodiment of the present disclosure may further include a current detection unit (not shown) that detects current flowing through the motor 41. The current detection unit may detect current flowing through the motor 41 during operation, and input the detected current value into the control unit 90.
[0126] The control unit 90 may control the motor 41 so that the drum 30 rotates at predetermined revolutions per minute.
[0127] The control unit 90 may control so that the drum 30 is stopped after being rotated in any one direction at predetermined revolutions per minute, and is rotated in a predetermined direction by changing the revolutions per minute after a predetermined time.
[0128] The control unit 90 may control to repeat an operation where the drum 30 is stopped after being rotated in any one direction and is rotated in an opposite direction after a predetermined time.
[0129] The control unit 90 may control to store a current value measured by the current detection unit while the drum 30 is rotated.
[0130] The control unit 90 may control so that the drum 30 reaches target rpm by rotating the drum in a stopped position in any one direction and accelerating it for a predetermined time, maintains the target rpm for a predetermined time, and then is stopped.
[0131] Preferably, the current detection unit may detect the motor current in a maintaining section among three sections, i.e. an acceleration section in which the drum 30 is accelerated to target rpm, the maintaining section in which the drum maintains the target rpm, and a stop section.
[0132] Meanwhile, the control unit 90 may calculate the average of current values of the maintaining section in which the drum 30 is rotated at predetermined revolutions per minute. The calculated average value may be stored in the memory and/or the control unit 90. FIGS. 4 to 6 are diagrams showing a state during drum stop, tumbling driving, and filtration driving, respectively, in a method of controlling a washing machine according to an embodiment of the present disclosure.
[0133] In this embodiment, as shown in FIGS. 4 to 6, the washing water may be heated using a coil 71 of the induction heater 70. Unless contradicting this, the sheath heater 12 may be provided on the lower portion of the tub. That is, the washing machine according to this embodiment may include both the induction heater 70 and the sheath heater 12, and may include only the induction heater 70.
[0134] Thus, a mode in which washing water is heated using the sheath heater 12 as in the prior art may be used. On the other hand, a mode in which the washing water is heated using the induction heater 70 without operating the sheath heater 12 may be used.
[0135] As shown in FIG 5, as the drum 30 rotates during tumbling driving, laundry may be moved up by the lifter 30 and then be fallen by gravity, and circulating water may be sprayed into the drum 30. Further, the induction module may be driven, so that the drum 30 may be heated.
[0136] As shown in FIG 6, during filtration driving or filtration driving in circulation driving, as the drum rotates, laundry W may come into close contact with the inner circumference of the drum 30 to rotate integrally with the drum 30. This is because the centrifugal force generated by the rotation of the drum 30 is larger than gravity. At this time, the circulating water 30 may be sprayed into the drum, and the induction heater 70 may be driven to heat the drum 30.
[0137] FIGS. 5 and 6 show a state where washing water is circulated to be sprayed from the top of the drum 30 to the inside of the drum 30, and a state where the induction heater 70 (coil 71) is driven to provide a varying magnetic field to the drum 30. An eddy current is generated in the drum by a change in magnetic field, and heat is generated by the eddy current.
[0138] Thus, as shown in FIGS. 4 to 6, a heater protection water level is destroyed in the entire heating section, so that the water level will be always lower than the lowermost end of the drum, i.e., will be equal to or less than a circulation water level.
[0139] As described above, the tumbling driving of the drum may be referred to as driving in which laundry in the drum is lifted and dropped as the drum rotates at about 40 to 46 RPM. The tumbling driving may be referred to as driving in which washing or laundry wetting is performed by mechanical force through the fall of laundry and the friction with the drum. Since this is driving in which laundry is stirred in the drum, this is commonly used.
[0140] That is, the revolution number of about 40 to 46 RPM may correspond to a revolution number range in which laundry is bent and dropped in the drum 30. A motion in which the laundry is bent and dropped in the drum 30 may be referred to as a tumble or tumbling process.
[0141] Meanwhile, the washing machine according to an embodiment of the present disclosure may perform a drying function. In this case, the washing machine according to an embodiment of the present disclosure may be a washer-dryer combo. On the other hand, the clothing treatment apparatus according to an embodiment of the present disclosure may be a dryer for drying laundry or wet clothing.
[0142] Air may be cooled and water may be condensed and discharged on the inner circumference of the tub 20. In other words, even if there is no air circulation in the tub 20, the drying may be performed by condensing water.
[0143] Cooling water may be supplied into the tub 20 to improve drying efficiency by more effectively condensing water. As a surface area where the cooling water meets the tub 20, that is, a surface area where the cooling water contacts air increases, it is more advantageous. To this end, the cooling water may be supplied while being widely spread from a rear surface, one side or both sides of the tub 20. Through the supply of the cooling water, the cooling water may flow along the inner surface of the tub 20 to prevent it from being introduced into the drum.
[0144] In order to perform the drying function, in some cases, a fan (not shown) for blowing air into the tub 20 and a duct (not shown) equipped with the fan may be further provided. The blowing fan may control the flow or air in the clothing treatment apparatus during the drying process.
[0145] The clothing treatment apparatus such as the dryer may not provided with the tub 20. The blowing fan may circulate the air of the drum 30. Meanwhile, a separate heater may not be provided for drying laundry. That is, the laundry may be dried using the above-described heater, e.g., the induction heater 70. That is, washing-water heating during washing, object heating during spin-drying, and object heating during drying may be performed through one induction heater 70.
[0146] When the drum 30 is driven and the induction heater 70 is driven, the entire outer circumference of the drum 30 may be substantially heated. While the heated drum 30 exchanges heat with wet laundry, the laundry may be heated.
[0147] In this process, the air inside the drum 30 may also be heated. Thus, when the air is supplied into the drum 30, air from which water is evaporated through heat exchange may be discharged to the outside of the drum 30.
[0148] The air supply position and the air discharge position may be determined so that heated air is evenly supplied to the drying object and humid air is smoothly discharged. To this end, air may be supplied from the upper portion of the front of the drum 30, and the air may be discharged through the rear of the drum 30.
[0149] As described above, the induction heater 70 may be driven as the drum 30 is driven. At this time, the laundry may repeatedly rise and fall as the drum 30 is driven. That is, drying may be performed by the above-described tumbling driving. At this time, since the heating position of the drum 30 is not the lower portion of the drum 30 but is the upper portion thereof, the overheating of the clothing can be effectively prevented.
[0150] FIG 7 is a schematic view of the washing machine according to an embodiment of the present disclosure.
[0151] As described above, the washing machine according to this embodiment may include two temperature sensors 28 and 29.
[0152] The washing-water temperature sensor 28 may be mounted on the lower portion of the tub 20 to sense the temperature of washing water. The drying temperature sensor 29 may be mounted on the upper portion of the tub 20 to sense the temperature of the outer circumference of the drum 30.
[0153] The control unit 90 controls the heating of washing water and the driving of the induction heater 70 (or the coil 71 of the induction heater 70, which will be commonly referred to as the induction heater 70) based on the temperature detected by the drying temperature sensor 29 when washing is performed.
[0154] As shown in FIG 7, the coil 71 of the induction heater 70 may be mounted on the upper portion of the tub 20. That is, the induction heater 70 may be mounted on the outer circumference of the upper portion of the tub 20. In the clothing treatment apparatus such as the dryer having no tub 20, the induction heater may be disposed on the inside or inner wall of a case. Even in this case, the induction heater 70 may be disposed on the upper portion of the drum 30. Due to the mounting position of the induction heater 70, the outer circumference of the upper portion of the drum may be heated by the induction heater 70.
[0155] Meanwhile, the induction heater 70 may be disposed on the upper side, lower side, left side or right side of the drum in the case to be spaced apart from the drum, in the clothing treatment apparatus having no tub, such as the dryer.
[0156] Such a position of the induction heater 70 may be determined to effectively prevent the overheating of an object, because the object in the drum 30 does not contact the upper portion of the drum in a state where the drum 30 is stopped. Thus, as the drum 30 rotates, the induction heater 70 may be controlled to be driven. This means that the object may be evenly heated.
[0157] Here, the mounting position of the drying temperature sensor 29 may be important. This is because the temperature of the drum 30 by heating should be optimally measured and simultaneously the temperature of air in the tub 20 should be optimally measured.
[0158] The mounting position of the drying temperature sensor 29 may be one side of the induction heater 70, and it is advantageous that the mounting position is a position outside a projection plane to the lower side of the induction heater 70. To be more specific, the drying temperature sensor 29 may be mounted on the right side of the tub 20 at an approximately 2 o'clock position.
[0159] The drying temperature sensor 29 may be mounted to pass from the outside to the inside of the tub 20. Thus, a signal line or wire of the drying temperature sensor 29 may be provided outside the tub 20, and a sensing portion for sensing may be mounted to partially protrude from the inner circumference of the tub 20 inward in a radial direction.
[0160] Thus, the drying temperature sensor 29 may directly sense the temperature of air in space between the outer circumference of the drum 30 and the inner circumference of the tub. Through the sensing temperature, the temperature of the outer circumference of the drum 20 may be indirectly and experimentally sensed or estimated.
[0161] The control unit 90 may control the driving of the induction heater 70 based on the temperature sensed by the drying temperature sensor 29. That is, in order to prevent the drum 30 from being overheated and to prevent the internal temperature of the tub 20 from being overheated, the drying temperature sensor 29 may be used.
[0162] It is possible to detect dryness or humidity using the basic function and characteristics of the drying temperature sensor 29.
[0163] Since the washing-water temperature sensor 28 is provided to detect the temperature of washing water, it may be mounted on the lower portion of the tub 20. Thus, the mounting position of the washing-water temperature sensor 28 may be the same as in a general washing machine. That is, it may be provided on the lower side in the tub 20 to be immersed in the washing water and sense the temperature of the washing water. The washing-water temperature sensor 28 may be provided on an upper portion spaced apart from the bottom surface in the tub 20. In this case, it may be located on the lower portion rather than the bottom surface of the drum 30. Thus, the drying temperature sensor 29 may be referred to as an upper temperature sensor, while the washing-water temperature sensor 28 may be referred to as a lower temperature sensor.
[0166] FIGS. 8 and 9 show changes in temperature detected by the upper temperature sensor 29 and the lower temperature sensor 28 and changes in temperature difference (Delta T). For instance, FIG 8 shows a case where a dry load is 3kg, and FIG 9 shows a case where a dry load is 6kg.
[0167] In the drying operation where a wet object is dried by heating the drum, the temperature change and the temperature difference may have different aspects depending on a section where drying proceeds.
[0168] As drying is performed, the overall temperature rises. It is possible to detect dryness using the temperature characteristics of the lower temperature sensor 28 mounted on the lower side of the tub 20. As the drying process proceeds, the temperature of the lower temperature sensor 28 may be changed as follows.
[0169] That is, in initial and intermediate stages of the drying, the amount of heat for heating wet steam may be the same as the amount of heat for cooling condensate. However, in a late stage of the drying, the amount of heat for cooling condensate may be relatively larger than the amount of heat for heating dry air. Thus, the temperature in the tub may be decreased.
[0170] In addition, in the initial and intermediate stages of the drying, the amount of heat for cooling condensate supplied from the rear of the tub 20 and the amount of heat for heating wet steam may be in an equilibrium state, and the detection value of the lower temperature sensor 28 may also increase as the overall temperature rises.
[0171] However, in the late stage of the drying, the wet steam in the tub 20 is changed into dry air. At this time, since the amount of heat for cooling condensate on the rear of the tub 20 becomes much larger than the amount of heat for heating the dry air, a value detected by the lower temperature sensor 28 may be decreased with the lapse of time.
[0172] When the dryness is detected using the change in temperature detected by the upper temperature sensor 29 and the lower temperature sensor 28 and the change in difference (Delta T) between these temperatures, the temperature difference value (Delta T) may vary depending on the temperature condition in the tub 20 such as intermittent drying or continuous drying or outside-air temperature, so that the dryness cannot be accurately detected.
[0173] Further, when the heating output of a heater 70 greatly fluctuates, the overall system temperature (e.g. temperature in the tub) also fluctuates greatly, so that the probability of false detection in dryness may increase. Further, depending on the temperature of the condensate, the false detection in dryness may occur.
[0174] As described above, when the dryness is detected using the change in temperature detected by the upper temperature sensor 29 and the lower temperature sensor 28 and the change in difference (Delta T) between these temperatures, it is highly likely to change depending on external environment and system environment. Therefore, the accuracy of dryness detection may be deteriorated, and false detection may occur.
[0175] In a clothing treatment apparatus, as the drying of laundry (clothing) is performed, the moisture content of a dried object is reduced, so that a weight is reduced. At this time, if the weight of the dried object is reduced, torque for rotating the drum 30 may be reduced, so that the intensity of motor current may be reduced compared to the initial stage of drying. Therefore, a clothing treatment apparatus according to an aspect of the present disclosure can determine the dryness of clothing on the basis of motor current during the drying operation.
[0176] Further, a clothing treatment apparatus according to an aspect of the present disclosure may perform the drying operation while changing the rpm of the drum 30, and may determine the dryness of clothing on the basis of motor currents when the drum 30 is driven at different rpms. In the process of drying laundry, the drum 30 containing the laundry may be driven. For instance, the drum 30 may be tumbling driven. In this case, wet laundry may have a relatively high current difference between the driving of the drum at high rpm and the driving of the drum at relatively low rpm. For example, if a water-balloon phenomenon occurs in the laundry, there may occur a large difference in motor current for driving when the laundry in which the water-balloon phenomenon has occurred is driven at high rpm and when the laundry is driven at low rpm. In contrast, dried laundry may have a relatively low current difference between the driving of the drum 30 at high rpm and the driving of the drum at relatively low rpm.
[0177] Therefore, using this phenomenon, the control unit 90 may determine the dryness of clothing, on the basis of the first current value when the drum 30 is driven at the first revolutions per minute and the second current value when the drum 30 is driven at the second revolutions per minute greater than the first revolutions per minute. Further, according to an aspect of the present disclosure, the current detection unit may periodically or aperiodically measure motor current when the drum 30 is driven at high rpm and at low rpm, and may store the measured motor current value in the control unit 90 and/or the memory.
[0178] Meanwhile, the control unit 90 may calculate the average value or the median value of current detected by the current detection unit in a predetermined section such as the maintaining section. For example, the first current value may be the first current average value obtained by averaging currents detected by the current detection unit in the section in which the drum is driven at the first revolutions per minute, and the second current value may be the second current average value obtained by averaging currents detected by the current detection unit in the section in which the drum is driven at the second revolutions per minute.
[0179] Meanwhile, the control unit 90 may determine dryness on the basis of at least one of the average value, the maximum value, the minimum value, and the median value of motor current detected by the current detection unit in the section where the drum 30 is driven at the predetermined rpm. If the current value that is the standard for determining dryness is not reduced to be less than the previously detected/calculated current value by a predetermined level or more, it may be determined that dryness is high.
[0180] According to an embodiment, the control unit 90 may determine dryness using at least one ratio of current values such as the average value, the maximum value, the minimum value, and the median value. For example, if the ratio of the first current value and the second current value is less than a predetermined reference value, it may be determined that the drying is sufficiently performed.
[0181] The control unit 90 may repeatedly perform an operation in which the drum 30 is driven at the first revolutions per minute and an operation in which the drum is driven at the second revolutions per minute, during the drying operation. Thus, it is possible to repeatedly perform the detection for at least one of the current values and the determination of dryness.
[0182] The control unit 90 may additionally perform or end the drying operation on the basis of the determined dryness.
[0183] FIG 10 is a flowchart showing a control method of a washing machine according to an embodiment of the present disclosure.
[0184] Hereinafter, the process of determining dryness using the motor current value by the above-described drum driving will be described in detail with reference to FIG 10.
[0186] As the drying operation starts, the motor 41 may drive the drum 30 at the first revolutions per minute (S10). The current detection unit may detect the first current value when the drum 30 is driven at the first revolutions per minute. The first current value may be stored in the control unit 90 and/or memory. Since the first current value is stored in the section where the drum 30 rotates at the first revolutions per minute, the section may be referred to as the first storing step S10.
[0187] According to an embodiment, the control unit 90 may control to perform the first storing step S10 of calculating the first current average value obtained by averaging currents detected by the current detection unit in the section where the drum is driven at the first revolutions per minute, and of storing the first current average value by the driving of the drum 30.
[0188] Next, the motor 41 may drive the drum 30 at the second revolutions per minute greater than the first revolutions per minute (S20). The current detection unit may detect the second current value when the drum 30 is driven at the second revolutions per minute. The first current value may be stored in the control unit 90 and/or the memory. Since the second current value is stored in the section where the drum 30 is rotated at the second revolutions per minute, the section may be referred to as the 12-th storing step S20.
[0189] According to an embodiment, the control unit 90 may control to perform the second storing step S20 of calculating the first current average value obtained by averaging currents detected by the current detection unit in the section where the drum is driven at the second revolutions per minute, and of storing the second current average value by the driving of the drum 30.
[0190] Of course, the orders of the first storing step S10 and second storing step S20 may be interchanged. That is, first, the drum 30 may be driven at the second revolutions per minute greater than the first revolutions per minute, and the second current value (second current average value) by the driving of the drum 30 may be stored. Subsequently, the drum 30 may be driven at the first revolutions per minute, and the first current value (first current average value) by the driving of the drum 30 may be stored.
[0191] At least one of the first revolutions per minute and the second revolutions per minute may be smaller than revolutions per minute at which the laundry accommodated in the drum 30 is attached to the drum 30 and is rotated. That is, at least one of the first revolutions per minute and the second revolutions per minute may be revolutions per minute corresponding to tumbling driving.
[0192] This is because the effect can be relatively large when drying is performed according to tumbling driving as described above. However, the revolutions per minute of tumbling may vary depending on a situation. The revolutions per minute (rpm) optimized for the tumbling driving may vary depending on variables such as the type of load (e.g., laundry), a weight and the like. In order to use a difference in current when driven at different rpms, it is preferable that a difference between the rpm of a low rpm section and the rpm of a high rpm section is more than a predetermined level.
[0193] For instance, the first revolutions per minute may be 60 rpm or less. Further, for instance, the second revolutions per minute may be 100 rpm or more.
[0194] Next, the control unit 90 may compare the first current value with the second current value (S30). For example, the control unit 90 may perform a calculation step (S30) of calculating the ratio of the first current value (first current average value) to the second current value (second current average value).
[0195] As such, when the load spin-dried in the washing machine or the drier is dried, the current average value obtained by tumbling rotation at relatively low revolutions per minute in an initial stage and the current average value obtained by tumbling rotation at relatively high revolutions per minute may be obtained, and the ratio of the values may be obtained (low rpm current average/high rpm current average).
[0196] Next, a determining step S40 of determining whether the drying of laundry is completed may be performed using the ratio of the first current average value to the second current average value.
[0197] Subsequently, the drying operation may be performed using the set drying motion (S50). That is, when it is determined that the drying of laundry is not completed in the determining step S40 of determining whether the drying of laundry is completed, the drying operation may be performed.
[0198] After the step S50 of performing the drying operation, the first storing step S10, the second storing step S20, the calculation step S30, and the determining step S40 may be re-performed.
[0199] Further, the first storing step S10, the second storing step S20, the calculation step S30, and the determining step S40 may be re-performed at regular time intervals. That is, after the drying operation is performed (S50), it may be determined whether a set time has elapsed (S60). In this case, when the set time has elapsed, the first storing step S10, the second storing step S20, the calculation step S30, and the determining step S40 may be re-performed.
[0200] Thus, the first storing step S10, the second storing step S20, the calculation step S30, and the determining step S40 may be re-performed at regular time intervals.
[0201] For example, the current average value for tumble driving at low and high revolutions per minute at the intervals of 10 minutes may be calculated and be compared with a previously measured value to check the drying progress degree.
[0202] On the other hand, when it is determined that the drying of laundry is completed in the determining step S40 of determining whether the drying of laundry is completed, additional drying may be subsequently performed for a predetermined time (S70) and drying may be ended.
[0203] For example, the step S40 of determining whether the drying is completed may determine that the drying is completed when the ratio of the first current value (first current average value) to the second current value (second current average value) is smaller than a specific value.
[0204] For example, when a difference between the previously measured current value ratio and the currently measured current value ratio is less than 5%, it may be determined that the drying is completed.
[0205] On the other hand, in order to precisely measure motor current in a washing machine or dryer using a fan, the fan may be driven at low speed or stopped driving to measure the motor current. That is, when the current detection unit detects current flowing through the motor, the fan may be driven at a speed less than a predetermined speed or be stopped.
[0206] FIG 11 is a graph showing a drying operation (drying motion) by the control method of the washing machine according to an embodiment of the present disclosure.
[0208] In this drying operation, the drum may be first rotated for a certain time at a first rpm clockwise, be rotated for a certain time at a second rpm larger than the first rpm, and then be stopped rotating.
[0209] For example, as shown in FIG 11, after the drum is rotated for a certain time at 40 rpm, the rpm may increase to 52 rpm and then the drum may be rotated for a certain time.
[0210] At this time, the drum may be rotated for a relatively longer time at high rpm. For example, after the drum is rotated for 27 seconds at 40 rpm, the drum may be rotated for 30 seconds at 52 rpm. Thereafter, the drum may stop driving for a certain time.
[0211] This operation may be repeatedly performed by changing the rotating direction counterclockwise. That is, the drum 30 may be driven by changing only the rotating direction of the drum 30 at the same rpm for the same time.
[0212] Subsequently, the rpm may be gradually increased. This increasing step may correspond to a certain number of times. For example, the initial driving rpm of the drum 30 may be increased stepwise from 40 rpm through 44 rpm to 48 rpm, and then the same operation may be repeated in a state where the rpm is reduced again.
[0213] This operation may be repeatedly performed until drying is completed. That is, when it is determined that the drying of laundry is not completed in the determining step S40 of determining whether the drying of laundry is completed, the above-described drying operation may be performed.
[0214] At this time, after the drying operation is performed and it is determined whether a set time has elapsed (S60) as described above, the first storing step S 10, the second storing step S20, the calculation step S30, and the determining step S40 may be performed again.
[0215] FIG 12 is a graph showing a change in current value by the control method of the washing machine according to an embodiment of the present disclosure.
[0216] The change in current value according to the driving of the drum 30 actually represents a change in the current value according to the elapse of time in a load (laundry) having the weight of 3kg.
[0217] Referring to FIG 12, it can be seen that the current value for driving the drum 30 is gradually reduced as drying time progresses.
[0218] As such, in the dryness determining method according to an embodiment of the present disclosure described above with reference to FIG 10, it can be seen that the current value or the current average value is gradually reduced with the elapse of time. That is, it can be seen that the ratio of the current average value is also gradually reduced.
[0219] The reduction in the current average value is because the moisture content of a dried object is reduced as the drying of laundry (clothing) is performed, so that a weight is reduced. That is, when moisture evaporates and the weight of the dried object is reduced, the torque for rotating the drum 30 may be reduced, so that the intensity of motor current may be reduced compared to that in the initial drying stage.
[0220] In addition, wet laundry may have a relatively high current difference between the driving of the drum at high rpm and the driving of the drum at relatively low rpm. In contrast, dried laundry may have a relatively low current difference between the driving of the drum at high rpm and the driving of the drum at relatively low rpm.
[0221] Therefore, using this phenomenon, current (average current) may be measured and stored when the drum 30 is driven at high rpm and low rpm as described above, and dryness may be determined to be resistant to external environment by using the ratio of the current value.
[0222] That is, since the dryness detection method using the motor current almost has no change due to external factors such as external environment and detects dryness using only motor current, it is relatively resistant to external environment. In other words, the dryness detection method according to an embodiment of the present disclosure may determine dryness without being affected by a change in external environment.
[0223] Further, since dryness is determined using the ratio of current when the drum 30 is driven at high revolutions per minute and low revolutions per minute, the influence of internal mechanical changes such as the motor can be minimized.
[0224] The above description is merely illustrative of the technical idea of the present disclosure, and those of ordinary skill in the art to which the present invention pertains can make various modifications and variations without departing from the essential characteristics of the present disclosure.
1. A clothing treatment apparatus comprising:
a drum for accommodating laundry;
a motor for driving the drum;
a drying unit for drying the laundry by heating the drum; and
a current detection unit for detecting a current flowing through the motor,
wherein drying of the laundry ends on the basis of a first current value detected by the current detection unit when the motor drives the drum at a first revolutions per minute and a second current value detected by the current detection unit when the motor drives the drum at a second revolutions per minute that are greater than the first revolutions per minute.
2. The clothing treatment apparatus of claim 1, wherein the first current value is a
first current average value obtained by averaging currents sensed by the current detection
unit in a section where the drum is driven at the first revolutions per minute, and
the second current value is a second current average value obtained by averaging currents
sensed by the current detection unit in a section where the drum is driven at the
second revolutions per minute.
3. The clothing treatment apparatus of claim 1, wherein the drying ends when a ratio
of the first current value to the second current value is less than a predetermined
reference value .
4. The clothing treatment apparatus of claim 1, wherein, during the drying, the operation
of driving the drum at the first revolutions per minute and the operation of driving
the drum at the second revolutions per minute are repeatedly performed.
5. The clothing treatment apparatus of claim 1, further comprising:
a fan rotating in at least a part of the section during the drying,
wherein the fan is driven at a speed less than a predetermined speed or is stopped, when the current detection unit detects current flowing through the motor.
6. The clothing treatment apparatus of claim 1, wherein at least one of the first revolutions
per minute and the second revolutions per minute is smaller than revolutions per minute
at which the laundry accommodated in the drum is attached to the drum and is rotated.
7. The clothing treatment apparatus of claim 1, wherein the first revolutions per minute
are 60 rpm or less.
8. The clothing treatment apparatus of claim 1, wherein the second revolutions per minute
are 100 rpm or more.
9. The clothing treatment apparatus of claim 1, further comprising:
a tub for accommodating the drum.
a tub for accommodating the drum.
10. The clothing treatment apparatus of claim 1, wherein the drying unit comprises an
induction heater for heating the drum during the drying.