Patent Description:
A laundry dryer may supply hot air to the inside of a drum in a situation in which laundry (e.g., clothes or bedclothes) to be dried is put into the rotating drum, such that the laundry dryer can remove moisture or humidity from the laundry to be dried.

Hot air to be supplied to the inside of the drum may be produced by electric resistance heat, combustion heat caused by a gas fuel, or a condenser constituting a heat pump cycle, such that the hot air can be supplied to the inside of the drum by activation of a circulation fan.

After laundry to be dried has been dehumidified and dried in the drum, air scheduled to exit the drum unavoidably includes moisture removed from the laundry, such that the resultant air is in a high temperature and humid state. In this case, dryers can be classified into a condensation-type dryer and an exhaust-type dryer according to methods of treating the air of high temperature and humidity.

The condensation-type dryer does not discharge the high temperature and humid air to the outside, and condenses moisture contained in the high temperature and humid air through heat exchange while allowing the high temperature and humid air to circulate therein. In contrast, the exhaust-type dryer directly discharges the high temperature and humid air to the outside. The condensation-type dryer is different in structure from the exhaust-type dryer in that condensation-type dryer has a structure for treating condensate water and the exhaust-type laundry dryer has a structure for exhausting the air.

On the other hand, in order to improve the drying efficiency of laundry, a laundry dryer having a means capable of spraying steam into the drum to sterilize laundry to be dried and the drum has been developed.

<CIT> relates to a laundry machine including a drum to receive laundry, a steam generator to generate steam to supply to the drum, a water container to hold water, and a pump configured to provide the water in the water container to the steam generator. A controller in the laundry machine can supply the water to the steam generator using the pump during the steam generation until the water reaches a predetermined water level.

<CIT> relates to a laundry dryer and how to use condensed water generated from the operation of the laundry dryer. In particular, it discloses how to supply steam using the collected condensed water. It discloses that the condensed water is supplied to the steam generator during the steam operation.

<CIT> has disclosed a steam spray-type laundry dryer that directly receives water for steam generation from an external water supply source, or receives such water for steam generation from a storage tank installed in the laundry dryer.

According to a conventional laundry dryer designed to supply water to a steam unit using the storage tank, when water stored in the storage tank is exhausted, a user separates the storage tank from the laundry dryer, refills the storage tank with water, and re-installs the storage tank in the laundry dryer, such that the storage tank of the laundry dryer can be replenished with water required for steam generation.

In this case, a water level sensor is installed in the storage tank to determine a level of residual water stored in the storage tank, such that the conventional laundry dryer can determine a water level of the residual water stored in the storage tank using the water level sensor. If there is a need to refill the storage tank with water, a water shortage notification message may be displayed on the laundry dryer such that the user can recognize such water shortage state of the storage tank.

Generally, a reed switch may be used as a water level sensor capable of measuring a water level of water stored in the storage tank. If the water level sensor is implemented as a reed switch, a water level measured when at least a predetermined amount of water remains in the storage tank due to a restricted sensing range of the water level sensor is determined to be a minimum water level.

Therefore, the conventional laundry dryer notifies the user of a water shortage state of the storage tank in a situation in which at least a predetermined amount of water remains in the storage tank. As a result, the user should refill (or replenish) the storage tank with water even though at least a predetermined amount of residual water is stored in the storage tank, resulting in user inconvenience.

In addition, the conventional laundry dryer unavoidably notifies the user of a water shortage state using a notification message even when a predetermined amount of water is stored in the storage tank, and the user may mistake the notification message for a malfunction.

Accordingly, the present invention is directed to a laundry dryer and a method for controlling the same that substantially obviate one or more problems due to limitations and disadvantages of the related art. The invention is defined by independent claims <NUM> and <NUM>.

An object of the present invention is to provide a laundry dryer capable of informing a user of a water shortage state indicating that a water level of water stored in a storage tank does not reach a target water level for enabling a steam unit to generate steam, and a method for controlling the same.

When the steam unit is not filled with water corresponding to a target water level, the laundry dryer may determine a water shortage state, such that the laundry dryer can provide a water shortage notification message in a situation in which the amount of residual water stored in the storage tank is minimized.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a laundry dryer includes a cabinet; a drum rotatably supported in the cabinet, and configured to receive hot air and steam; a steam unit disposed in the cabinet, and configured to generate the steam; a storage tank disposed in the cabinet, and configured to store water to be supplied to the steam unit; a supply pump disposed between the steam unit and the storage tank, and configured to transfer water stored in the storage tank to the steam unit; and a steam controller configured to operate the steam unit upon receiving a steam supply command so that the steam is supplied to the drum. If a water level of at least one of water stored in the steam unit and water stored in the storage tank is equal to or less than a predetermined water level, the steam controller provides a water shortage notification message for user recognition.

If a water level of at least one of water stored in the steam unit and water stored in the storage tank is equal to or less than a predetermined water level, the steam controller provides a water shortage notification message such that the user can recognize the water shortage notification message.

If steam is completely sprayed into the drum, the steam controller may operate the supply pump in a manner that the steam unit is filled with water corresponding to a predetermined target water level, so that water is supplied to the steam unit.

Although a predetermined time has elapsed from an operation start time of the supply pump, if the steam unit is not filled with water corresponding to the target water level, the steam controller may determine a water shortage state of the storage tank, and provides a water shortage notification message.

When determining the water shortage state of the storage tank, the steam controller may provide the water shortage notification message at any one of a first time where the water shortage state of the storage tank is determined and a second time where a subsequent steam supply command is input.

The steam unit may include a steam generator configured to store water received from the storage tank so as to generate steam, a spray nozzle configured to spray the steam generated by the steam generator into the drum, a water supply pipe configured to connect the supply pump to the steam unit so as to supply water stored in the storage tank to the steam generator, and a steam discharge pipe configured to connect the steam generator to the spray nozzle so that the steam generated by the steam generator is supplied to the spray nozzle.

The steam generator may include a steam housing configured to receive water received from the storage tank, a heater configured to heat water stored in the steam housing, and a water level sensor configured to measure a water level of the water stored in the steam housing.

The water level sensor may include a low water level sensor configured to measure a predetermined minimum water level in a manner that the heater is always immersed in the water stored in the steam housing, and a high water level sensor configured to measure the target water level to be stored in the steam housing for steam generation.

The water level sensor may include a low water level electrode installed at a position corresponding to the minimum water level to be stored in the steam housing, a high water level electrode installed at a position corresponding to the target water level to be stored in the steam housing for steam generation, and a common electrode installed at a position that is identical to or lower than that of the low water level electrode, and configured to be electrically connected to at least one of the low water level electrode and the high water level electrode through water stored in the steam housing, thereby recognizing a water level of stored water.

Although a predetermined time has elapsed from an operation start time of the supply pump, if the target water level is not satisfied, the steam controller may provide a water shortage notification message.

If the water level of water stored in the steam housing does not satisfy the minimum water level, the steam controller may operate the supply pump such that the minimum water level is satisfied.

The steam controller may provide the water shortage notification message through at least one of a display panel and a speaker.

In accordance with a method for controlling the laundry dryer, if the steam unit is not filled with water corresponding to a predetermined target water level, the water shortage state is determined, such that the laundry dryer can provide a water shortage notification message in a situation in which the amount of the residual water stored in the storage tank is minimized.

In accordance with another aspect of the present invention, a method for controlling a laundry dryer that dries laundry by supplying hot air and steam to a drum in which the laundry is placed according to claim <NUM> is provided.

The supplying the water stored in the storage tank to the steam unit may include supplying water by operating the supply pump until a water level of water stored in the steam unit satisfies a predetermined target water level, and if the target water level is satisfied or if a predetermined time has elapsed, stopping operation of the supply pump.

The supplying the water stored in the storage tank to the steam unit may include, if a predetermined time has elapsed from a specific time where there is no change in a current applied to the supply pump and load is not applied to the supply pump, stopping operation of the supply pump.

The determining the water shortage state may include, after lapse of a predetermined time in the supplying of the water, if the supply pump is stopped, determining that the target water level is not satisfied, thereby determining a water shortage state.

The performing the water shortage notification may include providing a water shortage notification message when the water shortage state is determined.

The performing the water shortage notification may include providing a water shortage notification message when a subsequent steam supply command is input.

The determining the water shortage state may include recognizing a water level of water stored in the storage tank, recognizing a water level of water stored in the steam unit, and if the water level of water stored in the storage tank is equal to or less than a predetermined water level, and if the water level of water stored in the steam unit does not satisfy the target water level, determining the water shortage state.

The performing the water shortage notification may include providing the water shortage notification message through at least one of a display panel and a speaker.

The method may further include, if a new drying process command is input after execution of the water shortage notification, and if the water level of water stored in the steam unit satisfies the target water level, proceeding to the supplying of the hot air.

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. In the following description, a detailed description of related known configurations or functions incorporated herein will be omitted to avoid obscuring the subject matter.

A laundry dryer and a method for controlling the same according to embodiments of the present disclosure will hereinafter be described with reference to the attached drawings.

<FIG> is a perspective view illustrating a laundry dryer <NUM> according to the present disclosure. <FIG> is a cross-sectional view illustrating the laundry dryer <NUM> according to the present disclosure.

Referring to <FIG> and <FIG>, a cabinet <NUM> forming an outer body of the laundry dryer <NUM> may include a front panel <NUM> to construct a front surface of the laundry dryer <NUM>, a back panel <NUM> to construct a back surface of the laundry dryer <NUM>, a pair of side panels <NUM> to construct side surfaces of the laundry dryer <NUM>, and a top panel <NUM> to construct a top surface of the laundry dryer <NUM>.

The front panel <NUM> may include an inlet <NUM> formed to communicate with a drum <NUM> to be described later, and a door <NUM> rotatably coupled to the cabinet <NUM> to open or close the inlet <NUM>.

The front panel <NUM> may include a control panel <NUM>.

The control panel <NUM> may include an input unit <NUM> to receive a control command from a user, a display unit <NUM> to display information such as a user-selectable control command thereon, and a main controller (not shown) to control a command required for performing procedures of the laundry dryer <NUM>.

The input unit <NUM> may include a power-supply request unit for requesting power supply from the laundry dryer <NUM>, a course input unit for selecting a user-desired course from among a plurality of courses, an execution request unit for requesting initiation of the user-selected course, and so on.

The display unit <NUM> may include at least one of a display panel and a speaker. The display panel may display and output characters and/or figures. The speaker may output a voice signal and a sound signal. The user who views information displayed on the display unit <NUM> can easily recognize a situation, a residual time, etc. of a current operating procedure of the laundry dryer <NUM>.

The cabinet <NUM> may include a drum <NUM>, a duct unit <NUM>, and a heat exchanger unit <NUM>. The drum <NUM> may be rotatably installed in the cabinet <NUM>, and may provide a space in which laundry is placed. The duct unit <NUM> may form a flow passage through which air discharged from the drum <NUM> is re-supplied to the drum <NUM>. The heat exchanger unit <NUM> may dehumidify and heat the air introduced into the duct unit <NUM>, and may re-supply the heated air to the drum <NUM>.

The drum <NUM> may include a cylindrical drum body <NUM>, a front surface of which is opened. The cabinet <NUM> may include a first support <NUM> and a second support <NUM>. The first support <NUM> may rotatably support the front surface of the drum body <NUM>. The second support <NUM> may rotatably support the back surface of the drum body <NUM>.

The first support <NUM> may include a first fixed body 22a fixed into the cabinet <NUM>, a drum inlet 22b formed to pass through the first fixed body in a manner that the inlet <NUM> can communicate with the inside of the drum body <NUM>, and a first support body 22c installed in the first fixed body 22a such that the first support body 22c is inserted into the front surface of the drum body <NUM>.

The first support <NUM> may further include a connection body 22d for connecting the inlet <NUM> to the drum inlet 22b. As illustrated in <FIG>, the connection body 22d may be formed in a pipe shape extending from the drum inlet 22b toward the inlet <NUM>. In addition, the connection body 22d may include an air outlet 22e formed to communicate with the duct unit <NUM>.

As can be seen from <FIG>, the air outlet 22e may be a passage for allowing internal air of the drum body <NUM> to flow into the duct unit <NUM>, and may be implemented as a through-hole formed to pass through the connection body 22d.

The second support <NUM> may include a second fixed body 23a fixed into the cabinet <NUM>, and a second support body 23b that is included in the second fixed body 23a and is inserted into the back surface of the drum body <NUM>.

The second support <NUM> may include an air inlet 23c that is formed to pass through the second fixed body 23a such that the inside of the drum body <NUM> communicates with the inside of the cabinet <NUM>.

In this case, the duct unit <NUM> may be configured to connect the air outlet 22e to the air inlet 23c.

The cylindrical drum body <NUM> may rotate through various shapes of drivers <NUM>.

For example, the driver <NUM> shown in <FIG> may include a motor <NUM> fixed into the cabinet <NUM>, a pulley <NUM> configured to rotate by the motor <NUM>, and a belt <NUM> configured to connect a circumferential surface of the pulley <NUM> to a circumferential surface of the drum body <NUM>.

In this case, the first support <NUM> may include a first roller R1 formed to rotatably support the circumferential surface of the drum body <NUM>, and a second roller R2 formed to rotatably support the circumferential surface of the drum body <NUM>.

However, the scope of the present disclosure is not limited thereto, a direct-driven type driver for rotating the drum by directly coupling the motor <NUM> to the drum without passing through the pulley and the belt can also be applied to the present disclosure within the scope of the present disclosure. A detailed description thereof will hereinafter be given with reference to one example of the driver <NUM>.

The duct unit <NUM> may include an exhaust duct <NUM> connected to the air outlet 22e, a supply duct <NUM> connected to the air inlet 23c, and a connection duct <NUM> provided with the heat exchanger unit <NUM> installed therein so as to connect the exhaust duct <NUM> to the supply duct <NUM>.

The heat exchanger unit <NUM> may be implemented as various devices capable of sequentially performing dehumidification and heating of air introduced into the duct unit <NUM>. For example, the heat exchanger unit <NUM> may be provided as a heat pump system.

In the heat pump system, the heat exchanger unit <NUM> may include a circulation fan <NUM>, a first heat exchanger (i.e., a heat absorption unit) <NUM>, and a second heat exchanger (i.e., a heating unit) <NUM>. The circulation fan <NUM> may enable the air to forcibly move along the duct unit <NUM>. The first heat exchanger <NUM> may perform a dehumidification function by lowering humidity of the air introduced into the duct unit <NUM>. The second heat exchanger <NUM> provided in the duct unit <NUM> may heat the air having passed through the first heat exchanger <NUM>. The circulation fan <NUM> may include an impeller 43a provided in the duct unit <NUM>, and an impeller motor 43b configured to rotate the impeller 43a.

The impeller 43a may be installed in any one of the exhaust duct <NUM>, the connection duct <NUM>, and the supply duct <NUM>. <FIG> illustrates an example of the impeller 43a provided in the connection duct <NUM> without being limited thereto. For convenience of description, the following description will hereinafter be given with reference to the example in which the impeller 43a is provided in the connection duct <NUM>.

The first heat exchanger <NUM> and the second heat exchanger <NUM> may be sequentially arranged in the direction from the exhaust duct <NUM> to the supply duct <NUM> within the connection duct <NUM>, and may be connected to each other through a refrigerant pipe <NUM> forming a circulation passage of the refrigerant.

The heat absorption unit implemented as the first heat exchanger <NUM> may transmit heat of the air introduced into the exhaust duct <NUM> to the refrigerant, thereby cooling the air and evaporating the refrigerant.

The heating unit implemented as the second heat exchanger <NUM> may transmit heat of the refrigerant having passed through the compressor <NUM> to the air, thereby heating the air and condensing the refrigerant.

In this case, moisture contained in the air may move along the surface of the first heat exchanger <NUM> while passing through the first heat exchanger <NUM>, such that the moisture is collected at the bottom surface of the connection duct <NUM>.

As described above, the heat exchanger unit <NUM> based on the heat pump system including the first heat exchanger <NUM> and the second heat exchanger <NUM> can be implemented as any one of known configurations, and a detailed description thereof will herein be omitted for convenience of description.

In order to collect condensate water collected at the bottom surface of the connection duct <NUM> after being condensed from the air having passed through the first heat exchanger <NUM>, a water collection unit <NUM> may be provided in the laundry dryer <NUM>.

The condensate water condensed in the first heat exchanger <NUM> may be primarily collected by the water collection unit <NUM>, and may be secondarily collected by a reservoir unit <NUM>. The water collection unit <NUM> may be provided in the connection duct <NUM>, and may be separately provided in a space spaced apart from the connection duct <NUM>.

The condensate water primarily collected by the water collection unit <NUM> may be supplied to the reservoir unit <NUM> through a condensate supply pipe <NUM>. In this case, a condensate pump <NUM> for smoothly discharging the condensate water may be installed in the condensate supply pipe <NUM>.

The reservoir unit <NUM> may include a reservoir tank <NUM> that can be drawn out from one side of the front panel <NUM> toward the outside. The reservoir tank <NUM> may be configured to collect condensate water received from the water collection unit <NUM> to be described later.

The user may withdraw the reservoir tank <NUM> from the cabinet <NUM> to remove condensate water from the reservoir tank <NUM>, and may then mount the reservoir tank <NUM> to the cabinet <NUM>. As a result, the laundry dryer according to the present disclosure may also be disposed in a place where a sewer or the like is not installed.

More specifically, the reservoir unit <NUM> may include a reservoir tank <NUM> and an inlet 72a. The reservoir tank <NUM> may be detachably coupled to the cabinet <NUM> to provide a space in which water is stored. The inlet 72a may be formed to pass through the reservoir tank <NUM> so that water discharged from the condensate supply pipe <NUM> is introduced into the reservoir tank <NUM>.

The reservoir tank <NUM> may be formed in a drawer-shaped tank that is drawn out from the cabinet <NUM>. In this case, the front panel <NUM> of the cabinet <NUM> may include a reservoir mounting hole in which the reservoir tank <NUM> is inserted.

A panel <NUM> may be fixed to the front surface of the reservoir tank <NUM>. The panel <NUM> may be detachably coupled to the reservoir mounting hole to form some parts of the front panel <NUM>.

The panel <NUM> may include a groove unit 71a into which a user hand is inserted such that the groove unit 71a can be grasped by the user hand. In this case, the panel <NUM> may serve as a handle that enables the reservoir tank <NUM> to be withdrawn from or inserted into the cabinet <NUM>.

The inlet 72a may be formed to receive condensate water discharged from a condensate nozzle <NUM> fixed to the cabinet <NUM>. The condensate nozzle <NUM> may be fixed to the top panel <NUM> of the cabinet <NUM> such that the condensate nozzle <NUM> is disposed over the inlet 72a when the reservoir tank <NUM> is inserted into the cabinet <NUM>.

The user may withdraw the reservoir tank <NUM> from the cabinet <NUM>, and may discard water stored in the reservoir tank <NUM> by turning over or tilting the reservoir tank <NUM> in the direction in which the inlet 72a is arranged. In order to easily discharge water stored in the reservoir tank <NUM> through the inlet 72a, a communication hole 72b may be formed to pass through the top surface of the reservoir tank <NUM>.

In addition, the laundry dryer <NUM> according to the present disclosure may include a first filter unit F <NUM> and a second filter unit F2 as a means for removing foreign materials such as lint or dust generated in a laundry drying process.

The first filter unit F <NUM> may be provided in the exhaust duct <NUM> that primarily filters out foreign materials contained in the air discharged from the drum <NUM>.

The second filter unit F2 may be disposed at a downstream side of the first filter unit F1 in a flow direction of air so as to secondarily filter out foreign materials contained in the air having passed through the first filter unit F1. More specifically, it may be preferable that the second filter unit F2 be disposed at an upstream side of the first heat exchanger <NUM> within the connection duct <NUM>. As a result, foreign materials contained in the air can be prevented from being accumulated in the first heat exchanger <NUM> acting as a heat absorption unit, such that throughput degradation or pollution of the first heat exchanger <NUM> can also be prevented.

A detailed structure of the first filter unit F <NUM> and the second filter unit F2 can be implemented as any means well known to those skilled in the art, and as such a detailed description thereof will herein be omitted for convenience of description.

Meanwhile, the laundry dryer <NUM> according to the present disclosure may further include a water supply unit <NUM> having an internal water supply unit <NUM> and an external water supply unit <NUM>, and a steam unit <NUM> configured to generate steam by receiving water from the water supply unit <NUM>.

The steam unit <NUM> may receive fresh water but not the condensate water, and may thus generate steam using the fresh water. In order to generate steam, the steam unit <NUM> may heat water, may use ultrasound, or may vaporize such water.

The steam unit <NUM> may receive water not only through the internal water supply unit <NUM> but also through the external water supply unit <NUM>, such that steam can be supplied to the inside of the drum body <NUM>.

The external water supply unit <NUM> may include a direct water-supply valve 82a adjacent or fixed to the back panel <NUM>, and a direct water-supply pipe 82b for supplying the steam unit <NUM> with water received from the direct water-supply valve <NUM>.

The direct water-supply valve 82a may be coupled to an external water-supply source. For example, the direct water-supply valve 82a may be coupled to a water supply pipe (not shown) extending to the back surface of the cabinet. For example, the direct water-supply valve 82a may be coupled to a water supply pipe (not shown) extending to the back surface of the cabinet. As a result, the steam unit <NUM> may be configured to directly receive water through the direct water-supply valve 82a.

Therefore, although the internal water-supply unit <NUM> is omitted or does not include water therein, the steam unit <NUM> may receive water required for steam generation through the direct water-supply valve 82a as necessary.

The direct water-supply valve 82a may be directly controlled by the steam controller <NUM>.

Although the steam controller <NUM> can be installed in the control panel <NUM>, the scope of the present disclosure is not limited thereto, and the steam controller <NUM> can also be implemented as a separate control panel to prevent overload of the control panel <NUM> and to prevent an increase in production costs. That is, the steam controller <NUM> may be included in a controller (not shown) disposed at the control panel <NUM> that controls commands of the input unit <NUM> and the display unit <NUM> and controls a command for performing a procedure of the laundry dryer <NUM>.

In this case, the steam controller <NUM> may be arranged adjacent to the steam unit <NUM>. The steam controller <NUM> may be mounted to the side panel <NUM> in which the steam unit <NUM> is installed, such that a control line connected to the steam unit <NUM> can be minimized in length.

Preferably, the steam unit <NUM> may be installed adjacent to the direct water-supply valve 82a. As a result, unnecessary residual water can be prevented from remaining in the direct water-supply valve 82b, and the steam unit <NUM> can immediately receive water as necessary.

On the other hand, the internal water-supply unit <NUM> may include a storage tank <NUM> for storing water therein, a supply pump <NUM> for receiving water from the storage tank <NUM> and supplying received water to the steam unit <NUM>, and a tank housing <NUM> for providing a space in which the storage tank <NUM> and the supply pump <NUM> are arranged.

The top panel <NUM> may include a tank withdrawal hole <NUM> that is formed in a region corresponding to an installation portion of the storage tank <NUM>.

The storage tank <NUM> is smaller in volume than the reservoir tank <NUM> of the reservoir unit <NUM>, such that the storage tank <NUM> can be easily withdrawn upward. Accordingly, the storage tank <NUM> may be configured to be easily withdrawn upward from the top panel <NUM>. As a result, since the withdrawal direction of the storage tank <NUM> is different from the withdrawal direction of the reservoir unit <NUM>, the possibility of user confusion may be greatly reduced.

The top panel <NUM> may include a withdrawal cover <NUM> that shields the tank withdrawal hole <NUM> to prevent the storage tank <NUM> from being arbitrarily drawn out.

The withdrawal cover <NUM> may include a panel connection unit <NUM> coupled to an outer circumferential surface of the tank withdrawal hole <NUM>. The panel connection unit <NUM> may extend from one side of the withdrawal cover <NUM> such that the withdrawal cover <NUM> can be rotatably coupled to the top panel <NUM>. The panel connection unit <NUM> and the top panel <NUM> may be hinge-coupled to each other.

On the other hand, a panel handle <NUM> that can be grasped by the user may be mounted on the withdrawal cover <NUM>. The panel handle <NUM> may be formed as a groove that is recessed downward from the withdrawal cover <NUM>.

A constituent element for informing the user of a water shortage state of the laundry dryer and a method for controlling the laundry dryer to inform the user of a water shortage state according to the present disclosure will hereinafter be described with reference to the attached drawings.

<FIG> is a schematic diagram illustrating an example of a connection state in which the storage tank, the supply pump, and the steam unit of the laundry dryer are coupled to each other according to the present disclosure. <FIG> is a cross-sectional view illustrating the steam generator of the laundry dryer according to the present disclosure.

Referring to <FIG> and <FIG>, the steam unit <NUM> for generating steam to supply the drum <NUM> with steam may be connected to the storage tank <NUM> through the supply pump <NUM>, and water stored in the storage tank <NUM> can flow into the steam unit <NUM> by activation of the supply pump <NUM>.

The steam unit <NUM> may include a steam generator <NUM>, a spray nozzle <NUM>, a water supply pipe <NUM>, and a steam discharge pipe <NUM>. The steam generator <NUM> may store water received from the storage tank <NUM>, and may generate steam. The spray nozzle <NUM> may spray steam generated by the steam generator <NUM> into the drum <NUM>. The water supply pipe <NUM> may connect the supply pump <NUM> to the steam unit <NUM> in a manner that water stored in the storage tank <NUM> can flow into the steam generator <NUM>. The steam discharge pipe <NUM> may connect the steam generator <NUM> to the spray nozzle <NUM> such that steam generated by the steam generator <NUM> can be supplied to the spray nozzle <NUM>.

The steam unit <NUM> may further include a shut-off valve <NUM> provided in the steam discharge pipe <NUM>. The shut-off valve <NUM> may shield (open or close) the steam discharge pipe <NUM> such that steam is supplied to the spray nozzle <NUM> or is not supplied to the spray nozzle <NUM>.

In this case, the supply pump <NUM> and the shut-off valve <NUM> can be controlled by the steam controller <NUM>.

In more detail, the steam generator <NUM> may generate steam by heating water stored in the storage tank. The steam generator <NUM> may include a steam housing <NUM> formed to store water received from the storage tank <NUM>, a heater <NUM> configured to heat water stored in the steam housing <NUM>, and a water level sensor <NUM> configured to measure a water level of water stored in the steam housing <NUM>.

In addition, the steam generator <NUM> may further include a temperature sensor <NUM> to measure a temperature of water stored in the steam housing <NUM>. The steam generator <NUM> may further include a pass pipe <NUM> provided in the steam housing <NUM> such that the steam generator <NUM> may discharge residual water stored in the steam housing <NUM> through the pass pipe <NUM> or may discharge water or steam through the pass pipe <NUM>.

The steam controller <NUM> may receive signals from the water level sensor <NUM> and the temperature sensor <NUM>, and may thus control the supply pump <NUM>, the heater <NUM>, and the shut-off valve <NUM> using the received signals.

For example, upon receiving a steam supply command, the steam controller <NUM> may recognize that a water level of water stored in the steam housing <NUM> reaches a target water level (H) using the water level sensor <NUM>. If the water level of water stored in the steam housing <NUM> does not reach the target water level (H), the steam controller <NUM> may operate the supply pump <NUM>. If the steam controller <NUM> recognizes that the water level of water stored in the steam housing <NUM> has reached the target water level (H) based on data received from the water level sensor <NUM>, the steam controller <NUM> may control the supply pump <NUM> to stop operation.

If the water level of water stored in the steam housing <NUM> reaches the target water level (H), the steam controller <NUM> may operate the heater <NUM>, may recognize that steam is generated in the steam housing <NUM> based on output data of the temperature sensor <NUM>, and may open the shut-off valve <NUM>, such that steam can be supplied into the drum through the spray nozzle <NUM>.

If it is determined that a water level of at least one of water stored in the steam unit <NUM> and water stored in the storage tank <NUM> is equal to or less than a predetermined water level, the steam controller <NUM> may provide a water shortage notification message such that the user who views the water shortage notification message can recognize a water shortage state of the laundry dryer <NUM>.

In this case, the water shortage notification message can be recognized by the user through at least one of the display panel and the speaker. That is, the display unit <NUM> may include at least one of a display panel capable of displaying characters, figures, etc. and the speaker capable of outputting a voice signal and a sound signal. Therefore, the water shortage notification message may be displayed on the display unit <NUM> using at least one of characters, figures, voice signals, and sound signals, such that the user can recognize the water shortage state of the laundry dryer.

In addition, the storage tank <NUM> includes a storage-tank water level sensor <NUM> configured to sense a water level of water stored in the storage tank <NUM>. The storage-tank water level sensor <NUM> may recognize the water level of water stored in the storage tank <NUM> using various water level measurement methods well known to those skilled in the art. For example, the storage-tank water level sensor <NUM> may recognize the water level of water stored in the storage tank <NUM> by measuring the weight of the storage tank <NUM>, or may recognize the water level of water stored in the storage tank <NUM> by sensing the height of a structure, the height of which is changed in response to the water level.

Therefore, the steam controller <NUM> may measure the water level of water stored in the storage tank <NUM> using the storage-tank water level sensor <NUM>, and may measure the water level of water stored in the steam housing <NUM> using the water level sensor <NUM> of the steam unit <NUM>. If the water level of at least one of water stored in the storage tank <NUM> and water stored in the steam housing <NUM> is equal to or less than a predetermined water level, a water shortage notification message can be displayed on the display unit <NUM> by the steam controller <NUM>.

More specifically, if a steam supply command is input to the steam controller <NUM> after execution of the drying operation, the steam controller <NUM> may operate the steam unit <NUM> to supply steam to the drum <NUM>. If steam is completely sprayed into the drum <NUM>, the steam controller <NUM> may operate the supply pump <NUM> until a water level of water stored in the steam housing <NUM> reaches the target water level (H) such that the supply pump <NUM> can be controlled to supply water to the steam housing <NUM>.

In this case, when the water level of water stored in the steam housing <NUM> does not reach the target water level (H) after lapse of a predetermined time from an operation start time of the supply pump <NUM>, the steam controller <NUM> may determine that there is no water in the storage tank <NUM>.

Of course, the steam controller <NUM> may receive load data of the supply pump <NUM>, and may determine whether a predetermined time (e.g., <NUM>~<NUM> seconds) has elapsed from a specific time where load is not supplied to the supply pump <NUM>. After lapse of the predetermined time (e.g., <NUM>~<NUM> seconds), if no load is supplied to the supply pump <NUM> and at the same time the water level of water stored in the steam housing <NUM> does not reach the target water level (H), the steam controller <NUM> may determine a water shortage state of the storage tank <NUM>. In this case, load data can be recognized through a change in current applied to the supply pump <NUM>.

Moreover, if the steam controller <NUM> determines a water shortage state of the storage tank <NUM>, the steam controller <NUM> may display a water shortage notification message at any one of a first time where the water shortage state of the storage tank <NUM> is determined and a second time where a subsequent steam supply command is input. In other words, as soon as the water shortage state is determined, the steam controller <NUM> may immediately display the water shortage notification message. Alternatively, if the steam supply command is input to the steam controller <NUM> after execution of the next drying operation, the steam controller <NUM> may display the water shortage notification message such that the user can recognize the water shortage state of the storage tank <NUM>. Of course, as soon as the water shortage state of the storage tank <NUM> is determined, the water shortage notification message is immediately displayed. Thereafter, when the subsequent steam supply command is input to the steam controller <NUM>, the water shortage notification message may be displayed again by the steam controller <NUM>.

The water level sensor <NUM> provided in the steam housing <NUM> may include a low water level sensor for measuring a minimum water level (L) to be stored in the steam housing <NUM>, and a high water level sensor for measuring a target water level (H) to be stored in the steam housing <NUM> for steam generation.

For example, the water level sensor <NUM> may include a low water level electrode 913b, a high water level electrode 913c, and a common electrode 913a. The low water level electrode 913b may be installed at a position corresponding to the minimum water level (L) to be stored in the steam housing <NUM>. The high water level electrode 913c may be installed at a position corresponding to the target water level (H) to be stored in the steam housing <NUM> for steam generation. The common electrode 913a may be installed at a position that is identical to or lower than that of the low water level electrode 913b, may be electrically coupled to at least one of the low water level electrode 913b and the high water level electrode 913c through water stored in the steam housing <NUM>, and may thus recognize the water level of water stored in the steam housing <NUM>.

In this case, the low water level electrode 913b may be arranged at an upper side of the heater <NUM> within the steam housing <NUM>. That is, the low water level electrode 913b may be arranged at an upper side of the heater <NUM> in a manner that the heater <NUM> can always be immersed in the water within the steam housing <NUM>.

Through the above-mentioned configurations, if the steam controller <NUM> determines that the water level of water stored in the steam housing <NUM> does not satisfy the minimum water level (L) based on data received from the common electrode 913a and the low water level electrode 913b, the steam controller <NUM> may operate the supply pump <NUM> without receiving the steam supply command, such that the minimum water level (L) can always be satisfied in the steam housing <NUM>. That is, in a situation in which the heater <NUM> is exposed outside without being immersed in water, if the heater <NUM> operates, the steam housing <NUM> may be heated and melted, resulting in occurrence of a fire. In order to address the above-mentioned issues, the steam housing <NUM> may be filled with water corresponding to a minimum water level (L) so that the heater <NUM> can always be immersed in water within the steam housing <NUM>.

After steam supply is completed, the steam controller <NUM> may operate the supply pump <NUM> in a manner that water required for subsequent steam generation can be prestored in the steam housing <NUM>. Thereafter, the steam controller <NUM> may control the supply pump <NUM> in a manner that the steam housing <NUM> can be filled with water corresponding to the target water level (H) through the common electrode 913a and the high water level electrode 913c.

In other words, upon receiving a steam supply command, the steam controller <NUM> may not supply water to the steam housing <NUM> by driving the supply pump <NUM>, and may allow the steam housing <NUM> to always be filled with water corresponding to the target water level (H) for steam generation. Thus, in a situation in which the steam housing <NUM> is filled with water corresponding to the target water level (H), if a steam supply command is input to the steam controller <NUM>, the steam controller <NUM> may generate and supply steam by operating the heater <NUM>, and may operate the supply pump <NUM> so that the steam housing <NUM> can be filled with water corresponding to the target water level (H). In this case, if the steam housing <NUM> is not filled with water corresponding to the target water level (H), the steam controller <NUM> may display a water shortage notification message for user recognition.

Through the above-mentioned configurations, if it is necessary to display the water shortage notification message in a situation in which the steam housing <NUM> is not filled with water corresponding to the target water level (H), the water shortage notification message may be displayed in a situation in which the amount of water stored in the storage tank <NUM> is minimized, such that the number of times that the user should refill the storage tank <NUM> with water can be minimized, resulting in an increase in user convenience.

When the water level of water stored in the storage tank <NUM> is measured using the storage-tank water level sensor <NUM> installed in the storage tank <NUM>, a specific state in which at least a predetermined amount of water is stored in the storage tank <NUM> may be determined to be a minimum water level according to measurement methods and structures of the storage-tank water level sensor <NUM>.

For example, assuming that the storage-tank water level sensor is implemented as a reed switch, a specific state in which <NUM>~<NUM> of water remains in the storage tank may be determined to be a minimum water level due to a restricted sensing range of the reed switch acting as the sensor. As a result, although <NUM>~<NUM> of water remains in the storage tank, the reed switch acting as the storage-tank water level sensor should unavoidably inform the user of a water shortage state of the storage tank, such that the user who recognizes the water shortage state has to replenish the storage tank with water, resulting in occurrence of user inconvenience.

In contrast, according to the embodiments of the present disclosure, even when residual water stored in the storage tank <NUM> does not satisfy the target water level (H) of the steam housing <NUM>, the supply pump <NUM> may operate in a manner that water stored in the storage tank <NUM> flows into the steam housing <NUM>. Thereafter, only when water capable of being supplied to the storage tank <NUM> through the supply pump <NUM> does not remain in the storage tank <NUM>, the water shortage notification message is displayed for user recognition. As a result, the number of times that the user should replenish the storage tank <NUM> with water can be minimized, resulting in an increase in user convenience.

Of course, in order to more correctly inform the user of the water shortage state, the laundry dryer according to the present disclosure may display the water shortage notification message for user recognition only when both the storage-tank water level sensor <NUM> and the water level sensor <NUM> of the steam unit <NUM> detect the water shortage state.

A method for controlling the laundry dryer according to the present disclosure will hereinafter be described with reference to the attached drawings.

<FIG> and <FIG> are flowcharts illustrating methods for controlling the laundry dryer according to the present disclosure.

Referring to <FIG> and <FIG>, a method for controlling the laundry dryer may include a hot-air supply step S <NUM>, a steam supply step S <NUM>, a water supply step S130, a water shortage determination step S140, and a water shortage notification step S150. In the hot-air supply step S110, when the drying process of laundry is performed, the laundry dryer may supply hot air to the drum. In the steam supply step S120, when the drying process of laundry is performed, the laundry dryer may supply steam to the drum through the steam unit. In the water supply step S130, the laundry dryer may operate the supply pump after completion of steam supply, such that water stored in the storage tank is supplied to the steam unit. In the water shortage determination step S140, after water is completely supplied to the steam unit, if a water level of at least one of water stored in the steam unit and water stored in the storage tank is equal to or less than a predetermined water level, the laundry dryer may determine occurrence of the water shortage state. In the water shortage notification step S150, the laundry dryer may display the water shortage notification message for user recognition.

In other words, according to the method for controlling the laundry dryer, upon receiving the steam supply command, the laundry dryer may not supply water to the steam unit by operating the supply pump, and may operate the supply pump after completion of steam supply so that water stored in the storage tank is supplied to the steam unit in a manner that the steam unit can be pre-filled with water corresponding to a target water level. In this case, when the steam unit is not filled with water corresponding to the target water level, the laundry dryer may determine a water shortage state of the storage tank, and may display a water shortage notification message.

In the water supply step S130, the laundry dryer may supply water to the steam unit by continuously operating the supply pump until a water level of water stored in the steam unit satisfies the target water level. If the target water level is satisfied or if a predetermined time has elapsed from activation of the supply pump, the laundry dryer may control the supply pump to stop operation.

Referring to <FIG>, if steam is supplied to the drum through the steam unit (S120), and if steam is completely supplied to the drum (Yes in S131), the laundry dryer operates the supply pump (S132) to fill the steam unit with water, such that water stored in the storage tank can be supplied to the steam unit.

If the steam unit is filled with water corresponding to the target water level (Yes in S141), the supply pump may stop operation (S142). That is, after completion of such steam supply, the steam unit can be filled with water corresponding to the target water level.

At this time, after the supply pump is driven (S132), in a situation in which the steam unit is not filled with water corresponding to the target water level (No in S141), if a predetermined time has elapsed (Yes in S143) from the above situation, the supply pump may stop operation (S144), and may display a water shortage notification message (S150).

For example, assuming that a time of about <NUM> seconds is required until the steam unit is filled with water corresponding to the target water level, although a time of about <NUM>-<NUM> seconds has elapsed from an operation start time of the supply pump, if the steam unit is not yet filled with water corresponding to the target water level, this means a water shortage state of the storage tank, such that a water shortage notification message is then displayed for user recognition. Of course, the above-mentioned time is merely an example for convenience of description, the scope of the present disclosure is not limited thereto, and the above-mentioned time can also be changed according to various conditions, for example, capacity of the steam unit, the amount of water to be supplied, capacity of the supply pump, etc..

Alternatively, as another example, the laundry dryer may measure a current applied to the supply pump, may measure load supplied to the supply pump based on a change in the current applied to the supply pump. Although a time of about <NUM>-<NUM> seconds has elapsed from a reference time where no load is applied to the supply pump, if load is not applied to the supply pump and at the same time the steam unit is not filled with water corresponding to the target water level, this means a water shortage state of the storage tank, such that a water shortage notification message may be displayed for user recognition.

Moreover, in the water shortage determination step S140, the laundry dryer may receive information about a water level of water stored in the storage tank using the storage-tank water level sensor installed in the storage tank, may receive information about a water level of water stored in the steam unit, and may then determine a water shortage state based on the received information. That is, in the water shortage determination step S140, if it is determined that the water level of water stored in the storage tank is equal to or less than a predetermined water level and the water level of water stored in the steam unit does not satisfy the target water level, this means a water shortage state. As a result, the laundry dryer may recognize both the water level of water stored in the storage tank and the water level of water stored in the steam unit, such that a water shortage state of the laundry dryer can be more correctly determined based on the recognized water levels.

In the water shortage notification step S150, the laundry dryer may display the water shortage notification message for user recognition using at least one of the display panel and the speaker. That is, the display unit of the laundry dryer may include at least one of the display panel for displaying characters, figures, etc., and the speaker capable of outputting voice signals and sound signals. Therefore, the water shortage notification message may be displayed on the display unit using at least one of characters, figures, voice signals, and sound signals, such that the user can recognize the water shortage state through the water shortage notification message.

In the water shortage notification step S150, if the water shortage state is determined in the water shortage determination step S140, the laundry dryer may display the water shortage notification message at any one of a first time where the water shortage state is determined and a second time where a subsequent steam supply command is input.

In other words, as soon as the water shortage state is determined in the water shortage determination step S140, the laundry dryer may immediately display the water shortage notification message. Alternatively, if the steam supply command is input to the laundry dryer after execution of the next drying operation, the laundry dryer may display the water shortage notification message so that the user can recognize the water shortage state. Of course, in the water shortage notification step S150, as soon as the water shortage state is determined, the laundry dryer may immediately display the water shortage notification message. Subsequently, when the subsequent steam supply command is input to the laundry dryer, the water shortage notification message may be displayed again. In addition, characters or figures indicating the water shortage state may be continuously displayed on the display panel as needed.

According to the method for controlling the laundry dryer, if a new drying process command is input to the laundry dryer after completion of the water shortage notification step S150, the laundry dryer may proceed to the hot-air supply step only when the water level of water stored in the steam unit satisfies a target water level.

For example, if the steam unit is not filled with water corresponding to the target water level, the water shortage notification message may be displayed. Thereafter, after the user who recognizes the water shortage notification message replenishes the storage tank with water, if a new drying process command is input to the laundry dryer, the laundry dryer may supply water corresponding to the target water level to the steam unit <NUM> by operating the supply pump, and may then proceed to the steam supply step.

In another example, although the water shortage notification message is displayed in a situation in which the steam unit is not filled with water corresponding to the target water level, if the user does not replenish the storage tank with water, and if a new drying process command is then input, the water shortage notification message may be displayed again. If the storage tank is replenished with water, the laundry dryer may operate the supply pump in a manner that the steam unit <NUM> can be filled with water corresponding to the target water level, and may then proceed to the above-mentioned steam supply step.

The laundry dryer and the method for controlling the same according to the present disclosure may control the steam housing to continuously receive water from the storage tank until the water level of water stored in the steam housing satisfies the target water level for steam generation. If the water level of water stored in the steam housing does not satisfy the target water level, the water shortage notification message may be displayed. As a result, the water shortage notification message may be displayed in a situation in which the amount of the residual water stored in the storage tank is minimized, such that the number of times that the user should refill the storage tank with water can be minimized, resulting in an increase in user convenience.

As is apparent from the above description, the laundry dryer and the method for controlling the same according to the embodiments of the present disclosure can determine a specific state in which a water level of water stored in the storage tank does not reach a target water level for enabling a steam unit to generate steam, to be a water shortage state, and can inform the user of a water shortage notification message after minimizing the amount of residual water stored in the storage tank. As a result, the number of times that the user should refill the storage tank with water can be minimized, resulting in an increase in user convenience.

The laundry dryer and the method for controlling the same according to the embodiments of the present disclosure can indirectly recognize the amount of water stored in the storage tank based on the amount of water supplied to the steam unit even when the water level sensor installed in the storage tank malfunctions or abnormally operates, such that occurrence of a water shortage notification message caused by a failure or malfunction of the water level sensor for the storage tank can be prevented.

In addition, the laundry dryer and the method for controlling the same according to the embodiments of the present disclosure can determine both a water level of water stored in the storage tank and a water level of water stored in the steam unit in response to data received from the water level sensor installed in the storage tank, such that the amount of residual water stored in the storage tank can be more correctly determined.

Claim 1:
A laundry dryer (<NUM>) comprising:
a cabinet (<NUM>);
a drum (<NUM>) rotatably supported in the cabinet (<NUM>) and configured to receive hot air and steam;
a steam unit (<NUM>) disposed in the cabinet (<NUM>) and configured to generate the steam;
a storage tank (<NUM>) disposed in the cabinet (<NUM>) and configured to store water to be supplied to the steam unit (<NUM>);
a supply pump (<NUM>) disposed between the steam unit (<NUM>) and the storage tank (<NUM>) and configured to transfer water stored in the storage tank (<NUM>) to the steam unit (<NUM>);
a water level sensor (<NUM>) configured to sense a water level of water stored in the steam unit (<NUM>);
a steam controller (<NUM>) configured to operate the steam unit (<NUM>) upon receiving a steam supply command so that the steam is supplied to the drum (<NUM>),
characterized in that
the laundry dryer further comprises a a storage-tank water level sensor (<NUM>) configured to sense a water level of water stored in the storage tank (<NUM>), and in that
the steam controller (<NUM>), based on that steam is completely sprayed into the drum (<NUM>), is configured to operate the supply pump (<NUM>) in a manner that the steam unit (<NUM>) is filled with water corresponding to a predetermined target water level (H), so that water is supplied to the steam unit (<NUM>), and
based on that a water level of at least one of water stored in the steam unit (<NUM>) and water stored in the storage tank (<NUM>) is equal to or less than a predetermined water level after water is completely supplied to the steam unit (<NUM>), the steam controller (<NUM>) is configured to provide a water shortage notification message for user recognition.