Patent Description:
In general, a clothes treatment apparatus may include a washing machine, a dryer, a device for refreshing clothes, and the like. The washing machine may be a washing machine with a drying function.

In the washing machine, a drum accommodating laundry is rotatably provided in a tub that provides a space for storing water. Through holes are formed in this drum, so that water in the tub flows into the drum. In this state, when the drum is rotated, the laundry in the drum flows and contaminants of the laundry is removed.

Such a washing machine is also provided with a heater for heating the water in the tub. The heater is generally operated in a state of being submerged in water in the tub, thereby directly heating the water. However, since this type of heater must always be operated in a state of being submerged in water for safety reasons, it can be used to heat the water in the tub but not suitable to heat air in the drum when there is no water in the tub or to heat wet laundry before spin-drying.

Recently, a washing machine with a drum capable of being heated by an induction heating system has been used. Such a washing machine may be configured to have a heat sensor disposed between the drum and a tank (or tub) to sense the temperature of water or air in the tank.

In this way, the temperature of the drum is inevitably estimated based on the temperature of water or air, but since the temperature of the drum is sensitively changed according to an output from the induction heating system, the temperature of water or air changes slowly, and thus, a value sensed by so the heat sensor may not exactly reflect the change in temperature of the drum.

Meanwhile, US Patent Application Publication No. <CIT> discloses a method of estimating temperature using a characteristic change of load (or drum) according to the temperature, especially an inductance change.

<FIG> shows a resonant circuit for employing this method.

Referring to <FIG>, a resonance circuit <NUM> may be used to turn off driving of a power device Q1 near zero crossing of a grid voltage, and at this time, and in this case, a resonance frequency may be measured using an autonomously resonant voltage (fres).

An inductance (Leq) may be derived using the resonant frequency (fres) measured in this way and a relational expression <MAT> showing a relationship among a resonant frequency, an inductance, and a capacitance.

Here, as the temperature increases, the relative magnetic permeability increases and the inductance (Leq) also increases. Therefore, the temperature of the drum (load) <NUM> can be estimated through the change in inductance (Leq) according to the temperature change.

<FIG> shows a voltage waveform when measuring a resonance frequency, and <FIG> shows an enlarged view of a part A shown in <FIG>.

Referring to <FIG>, it can be seen that a resonance frequency (fres) changes by about <NUM>% when a load temperature changes by <NUM>. That is, it can be seen that a variation of resonance frequency (fres) according to a change in temperature is too small to estimate the temperature using the resonance frequency.

That is, referring to <FIG>, it can be seen that a portion of the waveform W after the circuit is turned off is small to measure a fluctuation.

In addition, a change in inductance (Leq) fluctuates by <NUM>%/°C. That is, the change in inductance (Leq) may fluctuate by <NUM>% depending on the temperature. In addition, a capacitance (Ceq) in a formula for calculating the resonant frequency (fres) should be less than <NUM>% depending on a dispersion of components and a dispersion of temperature changes.

<FIG> is a graph illustrating a relationship between a temperature and a resonance frequency when estimating the temperature using the resonance frequency.

Due to the circumstances described above, when the temperature is estimated using the resonant frequency, an error of the estimated temperature may occur by about ±<NUM> or more. However, in order to apply the above-described method to general washing machines, accuracy within ±<NUM> is required.

In addition, there is a problem in that power of the circuit must be turned off for a predetermined time in order to measure a resonance frequency of (fres).

Therefore, an improvement or a new method of estimating temperature of a drum accurately by solving the aforementioned problems is required.

A short summary of the most relevant background art is given below:
<CIT> discloses a laundry treatment apparatus, which includes a tub, a drum formed of a metal material and rotatably provided inside the tub to accommodate laundry, an induction module spaced apart from a circumferential surface of the drum to heat the circumferential surface of the drum via a magnetic field that is generated when current is applied to a coil, a lifter provided in the drum to move the laundry inside the drum when the drum rotates, a temperature sensor provided to sense a temperature of the drum, and a module controller configured to control an output of the induction module so as to control an amount of heat generated from the circumferential surface of the drum. The module controller controls the amount of heat based on the temperature sensed by the sensor.

<CIT> presents a method for energizing an induction heater of a laundry dryer that includes energizing the induction heater to heat a drum of the laundry dryer; interrupting the energization of the induction heater for a time interval, allowing an oscillator circuit of the induction heater to freely oscillate; measuring a resonant frequency of the oscillator circuit during the time interval; and determining a temperature of the drum based on the measured resonant frequency.

<CIT> presents a contactless device for measuring at least the temperature of a rotor of a high-speed rotary machine, in particular a turbomolecular vacuum pump, comprises at least one magnetic capsule mounted on the rotor of the pump. The capsule comprises a permanent magnet and at least one pastille of ferromagnetic material having a Curie temperature slightly higher than a maximum temperature to be measured. The magnetic permeability of this material strongly depends on temperature. The pastille is intended to alter the magnetic field generated by the magnet. A detector carried by the stator of the pump generates pulses representative of the magnetic field varying with the rotor temperature, generated by the capsule, whenever the latter passes in front of the detector.

An aspect of the present disclosure is to solve the above and other problems.

Another object of the present disclosure provides a clothes treatment apparatus such as a dryer, a washing machine or a dryer combined with a washing machine, or an apparatus for refreshing clothes.

Yet another object of the present disclosure provides a clothes treatment apparatus capable of heating a drum with an induction heater and accurately estimating temperature of the drum.

Yet another object of the present disclosure provides a clothes treatment apparatus capable of accurately estimating temperature of a drum by minimizing influence of a magnetic field generated by an induction heater.

Yet another object of the present disclosure provides a clothes treatment apparatus capable of accurately estimating temperature of a drum regardless of a distance between a load (drum) and a tub.

Yet another object of the present disclosure provides a clothes treatment apparatus capable of estimating temperature of a rotating load (drum).

Yet another object of the present disclosure provides a clothes treatment apparatus capable of continuously estimating temperature, without turning off a power device in order to estimate the temperature.

Yet another object of the present disclosure provides a clothes treatment apparatus capable of minimizing vibration due to unbalance even when a drum including a magnet rotates at a high speed in order to estimate the temperature.

One or more objects are achieved by the invention set out by the features of the independent claim.

In an aspect of the present disclosure, a clothes treatment apparatus includes a magnet and a coil.

The magnet may be provided to be movable with respect to the coil.

The clothes treatment apparatus includes a drum rotatably provided.

The coil is fixed to an outside of the drum. The coil is disposed at a position overlapping the magnet in a longitudinal direction of a central axis of rotation of the drum.

The magnet is fixed to the drum. The magnet has a residual magnetic flux density that varies depending on temperature.

The magnet may be disposed at a position where a straight line passing through the coil and perpendicular to a rotation center line of the drum meets the drum. The magnet may be disposed at a portion of the drum which passes a point at a shortest distance from the coil according to rotation of the drum.

The magnet is disposed at an outer circumferential surface of the drum.

The clothes treatment apparatus includes an induction heater that heats the drum. The induction heater may generate a magnetic field. The induction heater heats the drum using the magnetic field.

The induction heater may be fixed to the outside of the drum.

The clothes treatment apparatus includes a cabinet. The cabinet may form an exterior of the clothes treatment apparatus.

The drum is rotatably provided in the cabinet.

The drum may include a body in an elongated cylindrical shape and through holes formed in the body.

The clothes treatment apparatus may further include a non-magnetic counterbalance part. The counterbalance parts may be provided as one or more balance counter parts.

The counterbalance part may be provided in the drum. The magnet and the one or more counterbalance part may be arranged at regular intervals along a circumferential direction of the drum.

The clothes treatment apparatus may further include a lifter provided at an inner circumferential surface of the drum. The lifter may include a plurality of lifters arranged at regular intervals along a circumferential direction of the drum. The lifter may protrude from the inner circumferential surface of the drum.

The magnet may be disposed at an outer surface of a portion of the drum where the lifter is disposed. The magnet may be disposed at a position corresponding to the lifter. The magnet may face the lifter.

The magnet may be disposed at an outer surface of a portion of the drum where any one of the plurality of lifters is disposed. The magnet may be disposed at a position corresponding to the any one of the lifters. The magnet may face the any one of the lifters.

The counterbalance part may be provided inside other lifters among the plurality of lifters.

The coil may be disposed on the opposite side of the induction heater with respect to a center of the drum. The coil may be disposed within a range of ±<NUM> degrees from an opposite point of the induction heater with respect to the center of the drum.

The clothes treatment apparatus includes a controller connected to the coil. The controller estimates the temperature of the drum.

A magnetic flux density of the magnet passing through the coil may change according to rotation of the drum. A counter electromotive force may be induced in the coil according to a change in magnetic flux density passing through the coil.

The controller estimates the temperature of the drum based on the counter electromotive force induced in the coil.

The clothes treatment apparatus may be a dryer. The clothes treatment apparatus may be a dryer that does not include a tub.

The coil may be fixed to the inside of the cabinet in the outside of the drum. The coil may be fixed to a bottom surface of the cabinet. The coil may be fixed to an inner surface of the cabinet.

The induction heater may be disposed inside or at an inner wall of the cabinet. In a tub-free clothes treatment apparatus such as a dryer, the induction heater may be located at an upper side, a lower side, a left side, or a right side of the drum in a cabinet spaced apart from the drum. The coil may be positioned at a position opposite to the induction heater or may be fixed to be spaced apart from the drum at a position spaced apart from the induction heater with respect to a rotation direction of the drum.

The clothes treatment apparatus may be an integrated washer-dryer that performs washing and drying. The clothes treatment apparatus may be an integrated washer-dryer including a tub.

The tub may be disposed inside the cabinet. The tub may accommodate the drum. The tub may provide a space for storing water.

The drum may be rotatably provided in the tub.

The coil may be installed in the tub. The coil may be fixed to the tub. The coil may be disposed at a position overlapping the magnet in a longitudinal direction of a central axis of rotation of the drum.

The induction heater may be fixed to the tub. The induction heater may be disposed on an outer circumferential surface of the tub. The induction heater may be spaced apart from the drum.

The coil may be disposed on the opposite side of the induction heater with respect to a center of the tub. The coil may be disposed within a range of ±<NUM> degrees from an opposite point of the induction heater with respect to the center of the tub.

According to the present disclosure, when a permanent magnet is attached to the drum of the clothes treatment apparatus and rotates, temperature of a rotating load (drum) may be estimated using a voltage (counter electromotive force) that is induced in a pickup coil installed in a tub equipped with an induction heater.

In a specific example, a primary side may be configured with a pickup coil and a secondary side may be configured with a permanent magnet.

The primary side may be attached in the opposite direction to minimize a magnetic effect of the induction coil, and the secondary side may be attached by using a structure to an outside of one of the lifters located inside the load (drum).

In this state, as the load (drum) rotates, when the permanent magnet attached to the inside of the lifter of the load (drum) passes the pickup coil, a predetermined voltage (counter electromotive force) is induced in the pickup coil.

As described above, the temperature of the load (drum) may be estimated by using a characteristic that the voltage (counter electromotive force) induced in the pickup coil decreases at a predetermined rate as the temperature of the permanent magnet increases.

As a specific example for the above, an embodiment of the present disclosure provides a clothes treatment apparatus including: a cabinet; a drum rotatably provided in the cabinet; an induction heater disposed outside the drum and heating the drum; a magnet fixed to the drum and having a residual magnetic flux density that changes depending on temperature; and a coil fixed to the outside of the drum and disposed to overlap the magnet in a longitudinal direction of a central axis of rotation of the drum.

Another embodiment of the present disclosure may include a tub; a drum rotatably provided in the tub and accommodating an object; an induction heater fixed to the tub while being spaced apart from the drum to heat the drum; a coil installed in the tub; and a magnet installed at an outer surface of the drum and positioned to pass through a point which interacts with the pickup coil while the drum rotates.

In addition, the magnet may include a permanent magnet whose residual magnetic flux density changes depending on temperature.

In addition, the magnet may be a ferrite magnet.

In addition, the magnet may be installed at the outer surface of the drum.

In addition, the magnet may be installed on an opposing surface of a lifter installation position in the drum.

In addition, the pickup coil may be installed on the tub within a range of ±<NUM> degrees from the opposite side of the induction heater.

In addition, the magnet may be installed at a position passing a shortest distance from the pickup coil according to rotation of the drum.

In addition, the drum may further include a counterbalance part installed at a position that bisects an angle of the drum with respect to a position to which the magnet is attached.

The controller may further include a controller connected to the pickup coil and configured to estimate the temperature of the drum by using a counter electromotive force value transmitted by interaction between the pickup coil and the magnet.

Also, the controller may estimate the temperature of the drum by using a characteristic that a voltage induced in the pickup coil decreases at a predetermined rate as the temperature of the magnet increases.

Yet another embodiment of the present disclosure includes a fixing part such as the cabinet, a rotating part rotating with respect to the fixing part, and a coil is disposed in the fixing part, and a magnet is disposed at a position corresponding to the coil in the rotating part. The magnetic flux density passing through the coil changes according to the rotation of the rotating part, and a counter electromotive force is induced in the coil. Provided is a clothes treatment apparatus in which a residual magnetic flux density of the magnet changes according to temperature of the rotating part and the temperature of the rotating part is determined based on a value of the counter electromotive force.

The fixing part may be an inner wall of the cabinet or any position inside the cabinet, and may be a tub disposed inside the cabinet to accommodate the rotating part.

In a dryer or clothes treatment apparatus without a tub, the coil may be disposed at an inner wall of the cabinet outside the rotating part.

The rotating part includes a drum disposed to rotate inside the cabinet or the tub. The magnet is disposed at the drum, and may be disposed at an outer surface or an inner surface of the drum.

A lifter may be provided inside the drum, and the magnet may be disposed in a drum area corresponding to the lifter. The magnet may be disposed at the outer surface of the drum corresponding to the lifter or at the inner surface of the drum on which the lifter is mounted.

The coil and the magnet are arranged to overlap each other in the longitudinal direction of the drum.

Yet another embodiment of the present disclosure provides a method of controlling a clothes treatment apparatus, the method including driving the clothes treatment apparatus; sensing a counter electromotive force through the pickup coil; and estimating temperature of the drum by using a magnitude of the counter electromotive force.

In addition, in the estimating of the temperature of the drum, the temperature of the drum may be estimated by using a value of a counter electromotive force according to a change in the residual magnetic flux density of the magnet depending on the temperature of the drum.

Further, the driving of the clothes treatment apparatus may include heating and rotating the drum.

Further, the driving of the clothes treatment apparatus may include aligning the pickup coil and the magnet.

Further, the estimating of the temperature of the drum may include estimating the temperature of the drum using a characteristic that a voltage induced in the pickup coil decreases at a predetermined rate as the temperature of the magnet increases.

According to the present disclosure, there may be effects as follows.

First, it may be possible to accurately estimate temperature of a drum by using a characteristic of a magnet that a residual magnetic flux density decreases as temperature increases.

In addition, it may be possible to estimate temperature regardless of a gap structurally caused due to a load (drum) and a tub.

In addition, it is possible to accurately estimate temperature even under a condition in which a load (drum) is rotating.

Without turning off a power device in order to estimate temperature, it is possible to continuously estimate the temperature, thereby yielding high efficiency when a product is applied.

Hereinafter, description will now be given in detail according to exemplary embodiments disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components may be provided with the same or similar reference numbers, and description thereof will not be repeated.

In general, a suffix such as "module" and "unit" may be used to refer to elements or components. Use of such a suffix herein is merely intended to facilitate description of the specification, and the suffix itself is not intended to give any special meaning or function.

In addition, in the following description of the embodiments, a detailed description of known functions and configurations incorporated herein will be omitted when it may impede the understanding of the embodiments. The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings.

While terms including ordinal numbers, such as "first" and "second," etc., may be used to describe various components, such components are not limited by the above terms. The above terms are used only to distinguish one component from another.

It will be understood that when an element is referred to as being "connected with" or "coupled to" another element, the element can be connected with or coupled to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly connected with" or "directly coupled to" another element, there are no intervening elements present.

In addition, it will be understood that, when an element, such as a layer, a region, or a module, is "on" another element, the element may be located "directly on" the other element and other elements may be interposed between both elements.

Furthermore, although each drawing is described for convenience of explanation, it is also possible that another embodiment realized by those skilled in the art by combining at least two or more drawings may also falls within the scope of the present disclosure.

A clothes treatment apparatus of the present disclosure may correspond to a washing machine, a dryer, and a dryer-integrated washing machine (integrated washer-dryer). Hereinafter, a washing machine will be described as a representative example of the clothes treatment apparatus of the present disclosure. However, the clothes treatment apparatus of the present disclosure is not limited thereto.

Hereinafter, a clothes treatment apparatus according to an embodiment of the present disclosure will be described with reference to <FIG>.

<FIG> is a perspective view illustrating the outside of a clothes treatment apparatus according to an embodiment of the present disclosure. <FIG> is a cross-sectional view illustrating the interior of a clothes treatment apparatus according to an embodiment of the present disclosure. <FIG> is a conceptual diagram in which a separate-type induction heater module is mounted on a tub.

A washing machine according to an embodiment of the present disclosure includes a drum <NUM> and an induction heater <NUM> provided to heat the drum <NUM>. The washing machine further includes a cabinet <NUM> forming an exterior. The washing machine may further include a tub <NUM>.

The tub <NUM> may be provided inside the cabinet <NUM>. The tub <NUM> may provide an accommodation space. The tub <NUM> may accommodate washing water. The tub <NUM> may be provided to accommodate the drum <NUM>.

The drum <NUM> is rotatably provided inside the cabinet <NUM>. The drum <NUM> may be rotatably provided inside the tub <NUM>. The drum <NUM> may provide a space for accommodating laundry. An opening may be provided at a front of the drum <NUM>, so that laundry can be put into the drum <NUM>.

Through holes <NUM> may be formed in a circumferential surface of the drum <NUM> so that air and wash water can communicate with each other between the tub <NUM> and the drum <NUM>. Hereinafter, the circumferential surface of the drum <NUM> is also referred to as a body of the drum <NUM>. The body of the drum <NUM> may extend in a cylindrical shape.

The drum <NUM> may be formed of a conductor. The body of the drum <NUM> may be formed of a conductor. The body of the drum <NUM> may be formed of metal.

The induction heater or IH module <NUM> may heat the drum <NUM>. The induction heater <NUM> may generate a magnetic field. The induction heater <NUM> may be provided to heat the drum <NUM> using the magnetic field.

The induction heater <NUM> may be provided at an outer circumferential surface of the tub <NUM>. The induction heater <NUM> may be provided on the tub <NUM>. The induction heater <NUM> may be fixed to the tub <NUM>. The induction heater <NUM> may be spaced apart from the drum <NUM>.

Alternatively, the induction heater <NUM> is disposed outside the drum <NUM> in the cabinet <NUM>. The induction heater <NUM> may be fixed to an inner wall of the cabinet <NUM>. The induction heater <NUM> may be spaced apart from the drum <NUM>.

The tub <NUM> and the drum <NUM> may be each formed in a cylindrical shape. Inner and outer circumferential surfaces of the tub <NUM> and the drum <NUM> may be each formed in a substantially cylindrical shape.

<FIG> shows a clothes treatment apparatus in which the drum <NUM> rotates about a rotational shaft parallel to the ground. Unlike the drawing, the drum <NUM> and the tub <NUM> may each have a tilting shape that tilts to the rear. The rotational shaft of the drum <NUM> may pass through the rear surface of the clothes treatment apparatus. That is, a straight line extending from a rotational shaft <NUM> of a driver <NUM> may pass through a rear surface of the clothes treatment apparatus.

The washing machine may further include the driver <NUM> provided to rotate the drum <NUM> inside the tub <NUM>. The driver <NUM> may include a motor <NUM>. The motor <NUM> may include the rotational shaft <NUM>. The rotational shaft <NUM> may be connected to the drum <NUM> to rotate the drum <NUM> inside the tub <NUM> and/or the cabinet <NUM>.

The motor <NUM> may include a stator and a rotor. The rotor may be connected to the rotational shaft <NUM>.

The driver <NUM> may include a spider <NUM>. The spider <NUM> may be an element that connects the drum <NUM> and the rotational shaft <NUM> and uniformly and stably transmits a rotational force of the rotational shaft <NUM> to the drum <NUM>.

The spider <NUM> may be coupled to the drum <NUM> while at least partially inserted into a rear wall of the drum <NUM>. To this end, the rear wall of the drum <NUM> may be formed in a shape recessed inward of the drum <NUM>. In addition, the spider <NUM> may be coupled to the drum <NUM> while further inserted into the drum <NUM> at a center of rotation of the drum <NUM>.

A lifter <NUM> may be provided inside the drum <NUM>. A plurality of lifters <NUM> may be provided along a circumferential direction of the drum <NUM>. The lifter <NUM> may perform a function of agitating laundry. For example, in response to rotation of the drum <NUM>, the lifter <NUM> lifts the laundry upward.

The laundry moved upward is separated from the lifter <NUM> due to gravity and falls downward. Washing may be performed by an impact force caused by the falling of the laundry. The agitation of the laundry may enhance drying efficiency.

The lifter <NUM> may be formed by extending from a rear end of to a front end of the drum <NUM>. The laundry may be evenly distributed back and forth in the drum <NUM>.

The induction heater <NUM> is a device for heating the drum <NUM>.

As shown in <FIG>, the induction heater <NUM> may include a coil <NUM> that receives a current to generate a magnetic field. The coil <NUM> may generate an eddy current in the drum <NUM>. Hereinafter, the coil <NUM> of the induction heater <NUM> may be referred to as a heater coil <NUM> to be distinguishable from a coil <NUM> which will be described later.

The induction heater <NUM> may include a heater cover <NUM> that accommodates the coil <NUM>. Hereinafter, descriptions about the structure of the induction heater <NUM> and the principle on how the induction heater <NUM> heats the drum <NUM> will be omitted.

In the washing machine, the coil <NUM> may increase temperature inside the drum <NUM> as well as the drum <NUM> itself by heating the drum <NUM>. By heating the drum <NUM>, the induction heater <NUM> may heat the wash water in contact with the drum <NUM>. The induction heater <NUM> may heat the laundry in contact with the inner circumferential surface of the drum <NUM>. By increasing the temperature inside the drum <NUM>, the induction heater <NUM> may heat the laundry that is not in contact with the inner circumferential surface of the drum <NUM>.

The induction heater <NUM> may increase the washing water, laundry, and the ambient temperature inside the drum <NUM>, thereby enhancing the washing performance. The induction heater <NUM> may dry the laundry by increasing the laundry, the drum <NUM>, and the ambient temperature inside the drum <NUM>.

Although <FIG> illustrates an example where the induction heater <NUM> is provided on the tub <NUM>, it does not exclude that the induction heater <NUM> is provided on at least one of the upper side, lower side, and both sides of the tub <NUM>. The induction heater <NUM> may be installed at a position higher than a maximum water level for the wash water stored in the tub <NUM>.

Furthermore, the clothes treatment apparatus such as a dryer may not include the tub <NUM>, and the induction heater <NUM> may be installed at an inner wall of the cabinet <NUM>.

The induction heater <NUM> may be provided at one side of the outer circumferential surface of the tub <NUM>. The coil <NUM> may be provided by winding the induction heater <NUM> in the cover <NUM> at least once along a surface adjacent to the tub <NUM>.

The induction heater <NUM> may generate an eddy current in the drum <NUM> by radiating an induced magnetic field directly on the outer circumferential surface of the drum <NUM>, and consequently may directly heat the outer circumferential surface of the drum <NUM>.

The clothes treatment apparatus according to an embodiment of the present disclosure includes a controller (which may be the same element as a controller <NUM> shown in <FIG>: hereinafter, the controller will be described using reference number <NUM>) for controlling output of the induction heater <NUM>. The controller <NUM> may control turning on/off and output of the induction heater <NUM>.

The induction heater <NUM> may receive power by being connected to an external power supply source via an electric wire. Alternatively, the induction heater <NUM> may be connected to the controller <NUM>, which controls the operation of the washing machine, to receive power. The induction heater <NUM> may receive power from anywhere as long as the induction heater <NUM> is able to supply power to an internal coil <NUM>.

When electric power is supplied to the induction heater <NUM> and AC current flows through the coil <NUM> provided in the induction heater <NUM>, the drum <NUM> is heated.

When electric power is supplied to the induction heater <NUM> but the drum <NUM> does not rotate, only some surface portions of the drum <NUM> is heated, and thus, the corresponding portions may be overheated and the remaining portions of the drum <NUM> may not be heated or may be less heated. In addition, heat may not be smoothly supplied to the laundry accommodated in the drum <NUM>.

When the induction heater <NUM> is operated, the controller <NUM> may rotate the drum <NUM> through the motor <NUM> of the driver <NUM>. The controller <NUM> may cause the induction heater <NUM> to operate once the drum <NUM> rotates.

When all of the outer circumferential surface of the drum <NUM> can face the induction heater <NUM>, a speed at which the motor <NUM> of the driver <NUM> rotates the drum <NUM> may be any speed.

Meanwhile, as the drum <NUM> rotates, all surfaces of the drum <NUM> may be heated, and the laundry inside the drum <NUM> may be evenly exposed to heat.

Accordingly, in the clothes treatment apparatus according to an embodiment of the present disclosure, even in a case where the induction heater <NUM> is installed at only one of the upper, lower, and both sides of the outer circumferential surface of the tub <NUM>, it is possible to evenly heat the outer circumferential surface of the drum <NUM>.

According to an embodiment of the present disclosure, the induction heater <NUM> may heat the drum <NUM> to a high temperature within a very short time. The induction heater <NUM> may heat the drum <NUM> to a target temperature within a very short time. The induction heater <NUM> may heat the drum <NUM> to <NUM> ° C or higher within a very short time.

When the induction heater <NUM> is driven while the drum <NUM> is stopped or rotating at a very slow rotating speed, a specific portion of the drum <NUM> may be overheated very quickly. When the induction heater <NUM> is driven in a state in which the drum <NUM> is stopped or at a very slow rotating speed, heat may not be sufficiently transferred from the heated drum <NUM> to the laundry.

A correlation between the rotating speed of the drum <NUM> and the driving of the induction heater <NUM> may be very important. It may be more advantageous to rotate the drum <NUM> and drive the induction heater <NUM> than to drive the induction heater <NUM> and rotate the drum <NUM>.

<FIG> is a schematic diagram illustrating a configuration of a clothes treatment apparatus according to an embodiment of the present disclosure.

Hereinafter, a configuration of a clothes treatment apparatus according to an embodiment of the present disclosure will be described in detail with reference to <FIG>.

The clothes treatment apparatus according to an embodiment of the present disclosure includes the coil <NUM> installed outside the drum <NUM> and a magnet <NUM> installed on the drum <NUM>. The magnet <NUM> may be installed on the drum <NUM> and rotate integrally with the drum <NUM>. The magnet <NUM> may be disposed at a position that passes through a point which interacts with the coil <NUM> while the drum <NUM> rotates. Hereinafter, the coil <NUM> may be referred to as a sensing coil <NUM> to be distinguishable from the coil <NUM> of the induction heater <NUM>.

A magnetic flux density of the magnet <NUM> passing through the coil <NUM> may change according to rotation of the drum <NUM>. Accordingly, an induced electromotive force (counter electromotive force) may be generated in the coil <NUM>.

For example, the coil <NUM> may be a pickup coil. The pickup coil refers to a coil in which a voltage is induced when passing through a permanent magnet.

The clothes treatment apparatus according to an embodiment of the present disclosure includes the controller <NUM> that estimates temperature of the drum <NUM> based on a value of a counter electromotive force generated by the interaction between the coil <NUM> and the magnet <NUM>. The controller <NUM> may be connected to the coil <NUM>.

The magnet <NUM> may have a residual magnetic flux density that changes according to the temperature. The magnet <NUM> may include a permanent magnet in which a residual magnetic flux density changes according to the temperature.

The residual magnetic flux density of the magnet <NUM> may decrease constantly as the temperature increases. In an example, in the case of a ferrite magnet, which is a type of permanent magnet, the residual magnetic flux density may change at a rate of -<NUM>%/°C. That is, when the temperature of the magnet increases by <NUM>, the residual magnetic flux density may decrease by <NUM>%.

When the permanent magnet is attached to the drum <NUM> of the dryer or washing machine and the drum <NUM> is rotated, a specific voltage may be induced at a portion where a strong magnetic field of the permanent magnet is generated (see <FIG>).

An induced voltage (counter electromotive force) may change by a magnetic flux density of the permanent magnet. Since the magnetic flux density changes according to the temperature of the permanent magnet, the temperature of the drum <NUM> may be estimated using the induced voltage (counter electromotive force).

Referring to <FIG>, the coil <NUM> may be installed on the tub <NUM> on the opposite side of the induction heater <NUM>. The coil <NUM> may be installed on the tub <NUM> on the opposite side of the heater coil <NUM>.

In addition, the coil <NUM> may be installed on the tub <NUM> at a position in a range of ±<NUM> degrees from the opposite side of the induction heater <NUM>. The coil <NUM> may be installed on the tub <NUM> at a position in a range of ±<NUM> degrees from the opposite side of the heater coil <NUM>.

For example, in the case of a washing machine, the coil <NUM> may be attached to the tub <NUM>. The coil <NUM> may be attached on the tub <NUM> at a position in the opposite direction of the coil <NUM> of the induction heater <NUM> in order to minimize the effect of a magnetic field generated in the coil <NUM> of the induction heater <NUM>.

Meanwhile, when there is no installation space in the opposite direction of the coil <NUM> of the induction heater <NUM> on the tub <NUM> due to other washing heaters, etc., the pickup coil <NUM> may be installed on the tub <NUM> within a portion between the positions of adjacent lifters indicated by the dotted line in <FIG>, that is, in a range within ±<NUM> degrees from the opposite side of the coil <NUM> of the induction heater <NUM>.

For example, the lifters <NUM> for lifting laundry may be installed inside the drum <NUM> at equal intervals. In this case, the magnet <NUM> may be installed at a position of one of these lifters <NUM>. For example, when three lifters <NUM> are installed at equal intervals on the inner circumference of the drum, an angle between the lifters <NUM> may be <NUM> degrees. When these lifters <NUM> are aligned as shown in <FIG>, the pickup coil <NUM> may be installed within a range of two lower lifters <NUM>.

The magnet <NUM> may be installed at a position passing through a shortest distance from the coil <NUM> according to rotation of the drum <NUM>. That is, when the drum <NUM> rotates, the magnet <NUM> installed at the drum <NUM> may pass through a position at the shortest distance from the coil <NUM>.

The magnet <NUM> may be installed at an outer side of the drum <NUM>, which corresponds to a position of a lifter <NUM> of the drum <NUM>. Here, the dotted line in <FIG> indicates the position of the lifter <NUM>.

This is because, when the magnet <NUM> is installed inside the drum <NUM>, it is not possible to transmit a magnetic force to the pickup coil <NUM> due to a material characteristics of the load (drum) <NUM>.

In the meantime, a counterbalance part <NUM> may be provided at a position that bisects a circular angle of the drum <NUM> with respect to a position where the magnet <NUM> of the drum <NUM> is attached, that is, at a position of another lifter <NUM>.

For example, since counterbalance may be necessary when the washing machine rotates at a high speed, it is possible to keep the weight in balance by attaching the counterbalance part <NUM> formed of a material having non-magnetic properties.

In this case, as described above, for example, when the lifters <NUM> are located at positions by which an angle of the drum <NUM> is divided into three equal parts and the magnet <NUM> is provided at any one of the positions, the counterbalance parts <NUM> may be installed at the other two positions.

For example, since the dryer may not rotate at a high speed, the counterbalance part <NUM> for keep the weight in balance may not be installed.

Referring to <FIG>, the controller <NUM> may be connected to the coil <NUM>.

<FIG> are partially enlarged views illustrating an installation position of a magnet of the clothes treatment apparatus according to an embodiment of the present disclosure.

<FIG> shows an inner side of the drum <NUM> and a position of a lifter <NUM>. <FIG> shows an outer side of the drum <NUM> as the opposite side of the corresponding part. Referring to <FIG>, it is shown that the magnet <NUM> may be installed at a portion of the outside of the drum <NUM> where the lifter <NUM> is located.

That is, referring to <FIG>, the magnet <NUM> may be installed at an outer surface of the drum <NUM> opposite to the position where the lifter <NUM> is installed on the inner surface of the drum <NUM>. The magnet <NUM> may be located at a center of the position where the lifter <NUM> is installed.

<FIG> is a diagram illustrating an example of a magnet of a clothes treatment apparatus according to an embodiment of the present disclosure. <FIG> shows a side cross-section of the magnet <NUM>, and <FIG> shows a front side of the magnet <NUM>.

Referring to <FIG>, the magnet <NUM> may include a magnet fixing part <NUM> and a magnet body <NUM> fixed by the magnet fixing part <NUM>. That is, the magnet <NUM> may include the magnet body <NUM> and the magnet fixing part <NUM>.

The magnet fixing part <NUM> may have a shape embracing the magnet body <NUM> and firmly fix the magnet body <NUM>. The magnet fixing part <NUM> may be open to expose at least one surface of the magnet body <NUM>. Here, the open surface of the magnet body <NUM> may be a surface facing the coil <NUM>. That is, the magnet fixing part <NUM> may fix the magnet body <NUM> so that the surface of the magnet body <NUM> facing the coil <NUM> is open.

<FIG> is a graph illustrating a voltage induced in a coil of a clothes treatment apparatus according to an embodiment of the present disclosure.

When the load (drum) is rotated at a rotating speed of <NUM> rpm, which is a driving speed of a dryer or an integrated washer-dryer, after a permanent magnet having positive poles (N pole and S pole) is attached onto the load (drum) <NUM>, it may be seen that a specific voltage is induced in the coil <NUM> at a point (X, Y) where a magnetic field of the permanent magnet is generated the strongest, as shown in <FIG>.

In this case, as mentioned above, the voltage (counter electromotive force) induced in the coil <NUM> may vary depending on a magnetic flux density of the permanent magnet. In addition, the magnetic flux density of the permanent magnet may change depending on temperature, and therefore, temperature of the drum <NUM> in which the permanent magnet is installed may be estimated.

<FIG> is a diagram illustrating a thermal equivalent model of a clothes treatment apparatus according to an embodiment of the present disclosure. <FIG> is a graph showing temperature tracking of a magnet when the thermal equivalent model shown in <FIG> is used.

In order to verify the present disclosure, a simulation may be performed regarding a temperature estimation time for temperature of the load (drum) <NUM> and temperature of the magnet <NUM>.

Here, a ferrite permanent magnet can be used as the magnet <NUM>.

In one example, in analyzing thermal conductivity of the permanent magnet, parameters of the permanent magnet may be set to have thermal resistance of <NUM> [K/W], heat capacity of <NUM> [J/K], mass of <NUM> [kg], and size of 50x40x5 [mm].

Based on these parameter, a thermal equivalent model as shown in <FIG> may be configured.

In <FIG>, on the side of the drum <NUM>, heat generated by the induction heater <NUM> may be regarded as power. On the side of the magnet <NUM>, a circuit including a thermal resistance Rth, a capacitance Cth and a heat source K of the magnet may be configured, and temperature Tdrum of the drum <NUM> may be derived from the heat source K. In addition, on the side of air, the thermal resistance Rth and the heat source K of the air may be included, and the temperature Tmag of the magnet may be derived from the heat source K.

In this equivalent model, when temperature change of the permanent magnet is simulated under a condition where heat of <NUM> is applied to the load (drum) <NUM>, it may be seen that about <NUM> seconds are taken to reach an error range within <NUM>%, as shown in <FIG>.

In the case of an integrated washer-dryer, temperature of the load (drum) may increase by up to <NUM>/sec under the condition of a maximum output (for example, <NUM>. 9kW), so it can be said that the time of <NUM> seconds to reach the temperature is allowable. Therefore, it can be seen that an embodiment of the present disclosure is applicable to a general washing machine.

Meanwhile, the thermal resistance in air may be considered.

When this simulation is performed, the thermal resistance of air may be <NUM>/W under a condition where a distance between the load (the drum <NUM>) and the ferrite permanent magnet is <NUM>.

Since the thermal resistance of air has a sufficiently large value of <NUM>/W, a temperature difference between the load (drum) and the permanent magnet under a thermal equilibrium condition may occur less than <NUM>.

<FIG> is a flowchart illustrating a method of controlling a clothes treatment apparatus according to an embodiment of the present disclosure.

According to an embodiment of the present disclosure, temperature of the drum <NUM> may be estimated using the configuration as described with reference to <FIG>.

That is, the temperature of the drum <NUM> may be estimated using the coil <NUM>, which is installed in the tub <NUM>, and the magnet <NUM>, which is installed on the drum <NUM> and positioned to pass through a point which interacts with the coil <NUM> while the drum <NUM> rotates.

Hereinafter, a process of estimating the temperature of the drum <NUM> of the clothes treatment apparatus by using the coil <NUM> and the magnet <NUM> will be described in detail with reference to <FIG> and <FIG> together.

First, operation <NUM> of driving the clothes treatment apparatus may be performed. In this case, as mentioned above, the clothes treatment apparatus may correspond to a washing machine, a dryer, and a dryer-integrated washing machine (integrated washer-dryer). Hereinafter, a washing machine LG Electronics Inc. , Seoul National University R&DB Foundation, Application No.: <CIT> will be described as a representative example of the clothes treatment apparatus of the present disclosure. However, the clothes treatment apparatus of the present disclosure is not limited thereto.

The operation S10 of driving the clothes treatment apparatus may include operation S11 of heating and rotating a load (drum) <NUM>.

In addition, the operation S10 of driving the clothes treatment apparatus may include operation S12 of aligning the magnet (permanent magnet) <NUM> and the coil <NUM>. The operation S12 of aligning the magnet <NUM> and the coil <NUM> may be performed automatically or manually in the washing machine. Also, in some cases, the operation S12 of aligning the magnet <NUM> and the coil <NUM> may be omitted.

When the operation S12 of aligning the magnet <NUM> and the coil <NUM> is performed, the operation S11 of heating and rotating the load (drum) <NUM> may be performed again after the operation S12.

In this case, a counter electromotive force may be generated in the coil <NUM> by rotation of the magnet (secondary side) <NUM> attached to the drum <NUM> in operation S13.

Thereafter, operation S20 of sensing a counter electromotive force generated in the coil (primary side) <NUM> through the controller <NUM> may be performed.

Then, operation S30 of estimating temperature of the drum <NUM> by using a magnitude of the counter electromotive force may be performed.

As mentioned above, a voltage (counter electromotive force) induced through the coil <NUM> may vary depending on a magnetic flux density of the permanent magnet. In addition, the magnetic flux density of the permanent magnet may change at a predetermined rate depending on the temperature, and thus, the temperature of the drum <NUM> in which the permanent magnet is installed may be estimated.

That is, in the operation S30 of estimating the temperature of the drum <NUM>, the temperature of the drum <NUM> may be estimated by using a counter electromotive force value according to a change in the residual magnetic flux density of the magnet <NUM> depending on the temperature of the drum <NUM>.

In other words, in the operation S30 of estimating the temperature of the drum <NUM>, the temperature of the drum <NUM> may be estimated by using a characteristic that the voltage induced in the coil <NUM> decreases at a predetermined rate as the temperature of the magnet <NUM> increases.

According to the present disclosure as described above, it may be possible to accurately estimate the temperature of the drum by using a characteristic of the magnet in which the residual magnetic flux density decreases as the temperature increases.

Claim 1:
A clothes treatment apparatus comprising:
a cabinet (<NUM>);
a drum (<NUM>) rotatably provided in the cabinet (<NUM>);
an induction heater (<NUM>) disposed outside the drum (<NUM>) and heating the drum (<NUM>); and
a magnet (<NUM>) fixed to the drum (<NUM>) and having a residual magnetic flux density that changes depending on temperature;
characterized in that:
the magnet (<NUM>) is disposed at an outer circumferential surface of the drum (<NUM>); and
the clothes treatment apparatus comprises:
a coil (<NUM>) fixed to the outside of the drum (<NUM>) and disposed to overlap the magnet (<NUM>) in a longitudinal direction of a central axis of rotation of the drum (<NUM>); and
a controller (<NUM>) configured to estimate the temperature of the drum (<NUM>) based on a value of a counter electromotive force induced in the coil (<NUM>) generated by the interaction between the coil (<NUM>) and the magnet (<NUM>).