Patent Description:
<CIT> relates to a washing machine and pump for a washing machine. The pump is driven by a brushless DC motor and can be controlled by a controller for controlling the speed of the pump to maintain a flow-rate of water being pumped from the washing machine at a desirable level.

<CIT> relates to a drum-type washing machine in which a load detector which detects a load on the circulation pump. When the load detector detects a predetermined change in the load of the circulation pump while the motor and the circulation pump are being driven, the controller stops driving the motor and stops a function of the circulation pump.

<CIT> relates to a washing machine in which a pump motor is controlled to rotate a circulation pump at a fixed rotation speed, a value of current supplied to the pump motor is set to correlate with a water level in a washing tub to detect the current value supplied to the pump motor, and washing tub water supply to the washing tub is stopped when the water level in the washing tub reaches a predetermined level.

In general, a laundry treatment machine performs a washing process using friction between laundry and a tub, which rotates by receiving a driving force from a motor, after detergent, water and the laundry are inserted into the tub, and thus can wash the laundry without damaging or tangling the laundry.

The general laundry treatment machine is configured to supply water into the tub, drain a part of water, supply water again, and then completely drain water as a washing process proceeds.

To circulate or drain water, the laundry treatment machine includes a pump attached to a drain hose connected to the tub, and the pump includes a motor. As the pump operates due to the motor, water flowing toward a drain is supplied into the tub again through a circulation hose or is drained through the drain hose.

When the flow of water is controlled as described above, the pump can brake if the pump continues operating after water is completely drained or stops operating while water is not completely drained.

In addition, if the drain is clogged with foreign substances, water is not normally drained. In this case, since water is not completely drained, the pump continues operating and thus is overloaded due to the abnormal flow of water.

Accordingly, controlling the pump by sensing a load state of the tub or the drain hose is necessary.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a laundry treatment machine for sensing a voltage applied to a motor included in a pump for circulation and drainage of water to determine a load state of water inside a tub, and controlling operation of the motor more efficiently. This object is solved with the features of the claims.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a laundry treatment machine including an outer tub for accommodating water for washing laundry, a water level sensor for measuring a level of water in the tub, a pump for draining or circulating water, wherein a motor for operating the pump is included in the pump, a motor driver for supplying operation power to the motor, a motor controller for setting a rotation speed of the motor and applying a signal for controlling the motor to the motor driver, a current sensor for measuring a current of the operation power supplied from the motor driver to the motor, a speed sensor for measuring a rotation speed of the motor, and a main controller for applying a control command to the motor controller to start or stop operation of the motor, wherein the main controller controls the motor to stop by determining a load state of water and determining whether the level of water in the outer tub is zero, based on the current measured by the current sensor and the rotation speed of the motor measured by the speed sensor. The main controller is further configured to determine that the level of water in the outer tub is zero, and control the motor to stop if the rotation speed is increased and the current is reduced. Furthermore, the main controller is configured to count a number of times that the motor stops, and determine that water is completely drained, based on the level of water in the outer tub measured by the water level sensor, if the number of times that the motor stops is equal to or greater than a reference number.

A laundry treatment machine according to embodiments of the present invention achieves the following effect. In operation of a pump for circulating and draining water, since the load of water to be drained is sensed and whether an error occurs due to foreign substances is determined based on a current and a rotation speed of a motor included in the pump, unnecessary operation of the pump may not be performed, damage of the pump due to overload may be prevented, noise due to pump operation in overloaded state may be solved, and the efficiency of pump control may be improved.

Hereinafter, the present invention will be described in detail by explaining embodiments of the invention with reference to the attached drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to one of ordinary skill in the art. In the drawings, like reference numerals denote like elements.

The terms "module" and "unit" used to signify components are used herein to help the understanding of the components and thus should not be construed as having specific meanings or functions. Accordingly, the terms "module" and "unit" may be used interchangeably.

<FIG> is a perspective view of a laundry treatment machine <NUM> according to an embodiment of the present invention, and <FIG> is a schematic diagram showing the configurations of a tub and a pump <NUM> of the laundry treatment machine <NUM>, according to an embodiment of the present invention.

Referring to <FIG> and <FIG>, the laundry treatment machine <NUM> according to an embodiment of the present invention is a top-loading laundry treatment machine in which laundry is inserted into a tub from above. The top-loading laundry treatment machine includes the concept of a washing machine for performing washing, rinsing and spin-drying processes after laundry is inserted, or a drying machine for performing a drying process after wet laundry is inserted, and the following description is focused on the washing machine.

The washing machine <NUM> includes a casing for forming the exterior of the washing machine <NUM>, manipulation keys for receiving a variety of control commands input by a user, a control panel for providing a user interface using, for example, a display for displaying information about an operation state of the washing machine <NUM>, and a door for opening or closing an opening through which laundry enters or exits.

The control panel includes an input unit including a plurality of manipulation keys for manipulating an operation state of the laundry treatment machine <NUM>, and a display unit for displaying the operation state of the laundry treatment machine <NUM>.

The washing machine <NUM> includes the tub. The tub includes an outer tub <NUM> for accommodating water, and an inner tub <NUM> rotatably provided in the outer tub <NUM> to accommodate laundry.

The washing machine <NUM> may include a pulsator <NUM> rotatably provided at the bottom of the tub and, more particular, at the bottom of the inner tub <NUM>.

A driving device (not shown) provides a driving force for rotating the inner tub <NUM> and/or the pulsator <NUM>. In addition, a clutch (not shown) for selectively delivering the driving force of the driving device may be provided to rotate only the inner tub <NUM>, to rotate only the pulsator <NUM>, or to simultaneously rotate the inner tub <NUM> and the pulsator <NUM>.

The inner tub <NUM> has a plurality of holes (not shown) and thus water supplied into the inner tub <NUM> flows through the holes to the outer tub <NUM>. A water inlet valve (not shown) for opening or closing a water inlet hose (not shown) may be provided to supply water into the tub.

Water in the outer tub <NUM> is drained through a drain hose <NUM>, and a drain valve (not shown) for opening or closing the drain hose <NUM>, and the pump <NUM> for pumping water are provided.

In this case, the pump <NUM> discharges water through the drain hose <NUM> to the outside of the washing machine <NUM>, or supplies water through a circulation hose <NUM> into the tub again, depending on a rotation direction thereof.

A spray nozzle <NUM> may be provided at an end of the circulation hose <NUM> and thus the circulated and re-supplied water may be sprayed.

When water is supplied into the tub through the water inlet hose, a water level sensor (not shown) senses the level of water. In this case, if water is supplied to a first point <NUM>, the level of water corresponds to a height from the location of the drain hose <NUM> to the first point <NUM> and a level <NUM> is measured.

<FIG> is a block diagram of the laundry treatment machine <NUM> according to an embodiment of the present invention.

The washing machine <NUM> includes an input unit <NUM>, an output unit <NUM>, a water level sensor <NUM>, a current sensor <NUM>, a motor controller <NUM>, a motor driver <NUM>, a motor <NUM>, a speed sensor <NUM>, a driving controller <NUM>, a driving device <NUM>, and a main controller <NUM> for providing overall control to the washing machine <NUM>. The washing machine <NUM> may further include a storage (not shown) for storing data.

In this case, the motor <NUM> is a motor of the pump <NUM> mounted on the drain hose <NUM> for drainage and circulation of water, and the motor controller <NUM> and the motor driver <NUM> are used to control operation of the motor <NUM> of the pump <NUM>. Although the washing machine <NUM> further includes a plurality of sensors and additional devices related to the driving device <NUM>, and other elements such as a water inlet valve and a drain valve, descriptions thereof are omitted herein and the following description is focused on a configuration for controlling the pump <NUM>.

As an input means including the input unit <NUM> is manipulated, a specific signal is input to the main controller <NUM>. The input unit <NUM> includes a plurality of manipulation keys provided on the control panel, and may further include a specific input means such as a touchpad.

The input unit <NUM> inputs setting data such as a washing mode, a washing temperature, a water level, or a reservation time, and inputs a control command for starting or stopping operation of the washing machine <NUM> depending on the setting data.

The output unit <NUM> outputs the setting data input through the input unit <NUM>, e.g., the washing mode, the washing temperature, or the water level, and outputs process information such as a current washing process state and a remaining washing time.

The output unit <NUM> includes a display means for displaying the setting data or the process information in the form of text, a number, or an image. In addition, the output unit <NUM> may include a buzzer (not shown) or a speaker (not shown) for outputting a specific sound effect or an alarm, and a lamp (not shown) to be turned on or off to output an operation state or a warning.

The storage stores basic data for controlling operation of the washing machine <NUM>, control data for controlling the operation, input and output data, and data input from a plurality of sensors while the washing machine <NUM> operates.

The driving controller <NUM> controls the driving device <NUM> to rotate based on a control command of the main controller <NUM>. The driving device <NUM> includes another motor which rotates under control of the driving controller <NUM>. The driving device <NUM> rotates at least one of the pulsator <NUM> or the inner tub <NUM>.

The water level sensor <NUM> includes at least one sensor and measures the water level <NUM> in the tub. As described above, if water is supplied to the first point <NUM>, the water level <NUM> is measured and provided to the main controller <NUM> and the motor controller <NUM>.

The motor controller <NUM> generates a control signal for driving the motor <NUM> to operate the pump <NUM> depending on a control command of the main controller <NUM>. The control signal generated in this case is a switching control signal, e.g., a pulse width modulation (PWM) signal.

In addition, the motor controller <NUM> generates a revolutions per minute (RPM) signal for controlling a rotation speed of the motor <NUM>, as a control signal depending on a sensed load state of water. This signal sets a target rotation speed of the motor <NUM> and is variable depending on the load state of water.

In this case, the motor controller <NUM> outputs the PWM signal through a resistor-capacitor (RC) filter in such a manner that the PWM signal is input to the motor driver <NUM>, and the RPM signal corresponds to a speed control voltage VSP, is set within a range from direct-current (DC) 1V to 4V, and is input to the motor driver <NUM>.

The motor driver <NUM> supplies a current having a specific magnitude as motor driving power to the motor <NUM> based on the control signals input from the motor controller <NUM>, i.e., the PWM signal and the RPM signal. In this case, the motor driver <NUM> includes a sensorless integrated circuit (IC) and a protection circuit.

As such, the motor <NUM> rotates and water of the drain hose <NUM> is drained or circulated and supplied into the tub again.

The motor <NUM> is a motor included in the pump <NUM> as described above. In this case, the motor <NUM> is a brushless DC (BLDC) motor.

The motor <NUM> rotates clockwise or counterclockwise under control of the motor controller <NUM> and the motor driver <NUM>, and thus the pump <NUM> drains or circulates water.

For example, water is drained if the motor <NUM> rotates clockwise, and is circulated and supplied through the circulation hose <NUM> into the tub again if the motor <NUM> rotates counterclockwise.

The current sensor <NUM> measures the current supplied from the motor driver <NUM> to the motor <NUM> and inputs the same to the motor controller <NUM>. In addition, the current sensor <NUM> inputs the sensed current to the main controller <NUM>. The current sensor <NUM> includes an amplifier.

The speed sensor <NUM> measures a rotation speed of the motor <NUM> and inputs the same to the motor controller <NUM>. In this case, the speed sensor <NUM> measures the speed by receiving a voltage of the motor <NUM>, and a comparative value between a DC link voltage and a distribution value, and calculates RPM corresponding to the voltage.

In addition, the speed sensor <NUM> inputs the rotation speed of the motor <NUM> to the main controller <NUM>.

The main controller <NUM> controls input and output of data to and from the input unit <NUM> and the output unit <NUM>, and controls the data to be stored in the storage. The main controller <NUM> sets operation of the washing machine <NUM> based on the setting data input through the input unit <NUM>, and thus controls the washing machine <NUM> to operate. As such, the washing machine <NUM> performs a washing process, a rinsing process, and a spin-drying process. A washer & dryer may further perform a drying process. The main controller <NUM> controls the display of the output unit <NUM> to display a washing mode, a washing time, a spin-drying time, a rinsing time, or a current operation state.

When the washing machine <NUM> operates and starts to wash laundry, the main controller <NUM> controls the drain valve not to drain water and controls the water inlet valve to supply water into the tub.

The main controller <NUM> controls the pump <NUM> to operate while the washing process or the rinsing process is performed, in such a manner that water is supplied through the circulation hose <NUM> into the tub again, and applies a control command to the motor controller <NUM> to drain water when the washing process and the rinsing process are completed.

In this case, the motor controller <NUM> generates a control signal for operation of the pump <NUM> depending on the control command of the main controller <NUM>, and applies the same to the motor driver <NUM>, and the motor driver <NUM> supplies motor driving power to the motor <NUM> to operate the pump <NUM>.

The main controller <NUM> receives the current of the motor <NUM> of the pump <NUM> from the current sensor <NUM>, receives the rotation speed of the motor <NUM> from the speed sensor <NUM>, and determines whether the level of water in the tub is zero based on the current and the rotation speed. In this case, the current input from the current sensor <NUM> and to the main controller <NUM> is a value converted by an analog to digital converter (ADC), and the rotation speed input from the speed sensor <NUM> to the main controller <NUM> is a speed signal timer-processed by an encoder.

In addition, the main controller <NUM> determines whether overcurrent occurs and determines the load of water, based on the current and the rotation speed of the motor <NUM>.

The main controller <NUM> inputs the results of determining whether the level of water is zero, whether overcurrent occurs, and the load, to the motor controller <NUM>. As such, the motor controller <NUM> receives a zero water level signal, an overcurrent signal, and load data from the main controller <NUM>, and reflects the same in a control signal for controlling the motor <NUM> of the pump <NUM>.

In this case, when a set process is performed, if the pump <NUM> operates for drainage or circulation of water, the main controller <NUM> applies a control command to the motor controller <NUM> to control the pump <NUM> to start operation depending on the water level of the water level sensor <NUM>. Furthermore, the main controller <NUM> applies a control command to the motor controller <NUM> to control the pump <NUM> to stop operation depending on whether the level of water is zero, while the pump <NUM> operates.

In addition, the main controller <NUM> determines whether the washing machine <NUM> normally operates, based on data input from a plurality of sensors, and outputs an error through the output unit <NUM> if an error occurs.

<FIG> is a schematic diagram showing signal information depending on sensing of the load of the laundry treatment machine <NUM>, according to an embodiment of the present invention.

Referring to <FIG>, the main controller <NUM> determines whether the level of water is zero, determines whether overcurrent occurs, and determines the load of water, based on the current of the motor <NUM>, which is input.

from the current sensor <NUM>, and the rotation speed (e.g., RPM) of the motor <NUM>, which is input from the speed sensor <NUM>.

The main controller <NUM> determines that the level of water is zero, if the input rotation speed is increased and the current is reduced, according to a load sensing algorithm. In this case, the main controller <NUM> determines whether water is drained and the level of water is zero, in further consideration of the water level input from the water level sensor <NUM>.

Based on the input rotation speed of the motor <NUM> of the pump <NUM> and the current, the main controller <NUM> determines the load of water and determines whether overcurrent occurs, if the rotation speed of the motor <NUM> of the pump <NUM> is reduced and the current is increased.

Depending on the determination result of the main controller <NUM>, a zero water level signal, an overcurrent signal, and a load signal are input to the motor controller <NUM>, and the current of the current sensor <NUM>, the rotation speed of the speed sensor <NUM> (e.g., a currently measured RPM), and the water level of the water level sensor <NUM> are input to the motor controller <NUM>. In addition, a target RPM of the motor <NUM> for driving the pump <NUM> is input from the main controller <NUM> to the motor controller <NUM>.

The motor controller <NUM> generates a PWM signal based on the input data, sets a rotation speed of the motor <NUM>, and inputs the rotation speed to the motor driver <NUM>, and the motor driver <NUM> supplies driving power based thereon to the motor <NUM>. The current sensor <NUM> senses and inputs an output current input from the motor driver <NUM> to the motor <NUM>, to the motor controller <NUM> and the main controller <NUM>, and measures and inputs a rotation speed of the speed sensor <NUM> to the motor controller <NUM> and the main controller <NUM> if the motor <NUM> operates.

As such, the motor controller <NUM> varies control of the motor <NUM> based on the target RPM, the actually measured RPM, and the current value in consideration of the load state of water, whether the level of water is zero, and whether overcurrent occurs.

In addition, the main controller <NUM> applies a control command to the motor controller <NUM> to stop or restart operation of the motor <NUM> based on the load state of water, whether the level of water is zero, whether overcurrent occurs, and variations in current value and rotation speed.

<FIG> is a graph showing the relationship between a voltage and a rotation speed of the motor <NUM> in controlling the laundry treatment machine <NUM>, according to an embodiment of the present invention. In this case, a first line L1 shows an unloaded state, and a second line L2 shows a loaded state of water.

As illustrated in <FIG>, a rotation speed RPM of the motor <NUM> is increased in proportion to a speed control voltage VSP of the motor controller <NUM>.

In addition, when water is present in the tub, the relationship between the voltage and the rotation speed in the loaded state and the relationship in the unloaded state (i.e., zero water level) are compared as described below. At the same speed control voltage, the rotation speed of the motor <NUM> measured when water is not loaded (i.e., when the level of water is zero) is higher compared to that measured when water is present.

If cases of a first voltage V1 and a second voltage V2 are compared, the rotation speed of the motor <NUM> is increased in proportion to the voltage depending on the load of the water.

Accordingly, if a timing when water starts to be drained, a timing when the level of water is a half of an initial water level, and a timing when water is completely drained and thus the level of water is zero water are compared, the rotation speed of the motor <NUM> of the pump <NUM> is increased as the load of water is reduced.

In this case, if a drain filter is clogged with foreign substances, water may not be normally drained and thus a current for driving the motor <NUM> may be increased. In addition, it may be determined whether water is normally drained, based on a variation in the rotation speed of the motor <NUM> measured for a preset drain time.

As such, the main controller <NUM> may determine that an error occurs and thus output the error through the output unit <NUM>.

<FIG> is a flowchart of a method for controlling the laundry treatment machine <NUM> outside the scope of the claimed invention.

If the washing machine <NUM> starts operation depending on setting data and drains water in a washing process or a rinsing process, the main controller <NUM> applies a drain command to the motor controller <NUM> (S310).

The motor controller <NUM> generates a control signal for controlling the motor <NUM> of the pump <NUM>, and sets a voltage for setting a speed of the motor <NUM> (S320 and S330).

The motor driver <NUM> receives the control signal of the motor controller <NUM> and supplies driving power to the motor <NUM>, and thus the motor <NUM> rotates and operates (S340).

In this case, the speed sensor <NUM> measures the rotation speed of the motor <NUM> (S360), and applies the measured rotation speed to the main controller <NUM> and the motor controller <NUM>. The motor controller <NUM> generates a control signal for subsequent control of the motor <NUM> based on the input rotation speed.

The main controller <NUM> determines whether the measured rotation speed of the motor <NUM> is increased by a certain rate or more (S370). In this case, the main controller <NUM> determines whether the rotation speed of the motor <NUM> is increased by <NUM>% or more compared to a premeasured rotation speed.

If the rotation speed of the motor <NUM> is increased by the certain rate or more, the main controller <NUM> applies a motor stop command to the motor controller <NUM> (S400).

Meanwhile, the current sensor <NUM> measures a current applied from the motor driver <NUM> to the motor <NUM> (S380).

The main controller <NUM> compares the measured current value to a previous current value, and determines whether the current is reduced (S390). For example, the main controller <NUM> may determine whether the current is reduced by <NUM>% or more.

If the current is reduced by a certain value or more, the main controller <NUM> applies a motor stop command to the motor controller <NUM> (S400).

Otherwise, if the current is not reduced or is reduced by a value less than the certain value, or if the speed is not increased or is increased by a rate less than the certain rate, the motor <NUM> continues operating. While the motor <NUM> operates, the rotation speed and the current value thereof are sensed and variations therein are monitored.

As such, the main controller <NUM> determines whether overcurrent is supplied to the motor <NUM>, a load state, or whether the level of water is zero, based on the variations in the rotation speed and the current.

The main controller <NUM> stops the motor <NUM>, counts the number of times that the motor <NUM> stops, and determines whether the number of times that the motor <NUM> stops is equal to or greater than a reference number (S410).

If the number of times that the motor <NUM> stops is less than the reference number, after a specific period of time passes (S420), the main controller <NUM> applies a motor driving command to the motor controller <NUM> to drive the motor <NUM> again.

Otherwise, if the number of times that the motor <NUM> stops is equal to or greater than the reference number, the main controller <NUM> controls the water level sensor <NUM> to measure the level of water (S430).

The main controller <NUM> determines whether water is completely drained to a designated level, based on the measured level of water (S450). If water is not completely drained, the motor <NUM> is driven again to operate the pump <NUM> again.

If water is completely drained, the main controller <NUM> determines that drainage is completed (S460), and the method proceeds to a subsequent process.

Therefore, according to the present invention, a load state of water and an error in drainage due to, for example, foreign substances are sensed and overcurrent supplied to a motor is determined depending on variations in rotation speed and current value of the motor. Thus, operation of the motor is controlled. As such, the motor may be protected, may achieve noise reduction, and thus may be controlled more efficiently.

Although all elements constituting the embodiments of the present invention are described to be integrated into a single one or to be operated as a single one, the present invention is not necessarily limited to such embodiments.

Claim 1:
A laundry treatment machine comprising:
an outer tub (<NUM>) for accommodating water for washing laundry;
a water level sensor (<NUM>) for measuring a level (<NUM>) of water in the outer tub (<NUM>);
a pump (<NUM>) for draining or circulating water, wherein a motor (<NUM>) for operating the pump (<NUM>) is comprised in the pump (<NUM>);
a motor driver (<NUM>) for supplying operation power to the motor (<NUM>);
a motor controller (<NUM>) for setting a rotation speed of the motor (<NUM>) and applying a signal for controlling the motor (<NUM>) to the motor driver (<NUM>);
a current sensor (<NUM>) for measuring a current of the operation power supplied from the motor driver (<NUM>) to the motor (<NUM>);
a speed sensor (<NUM>) for measuring a rotation speed of the motor (<NUM>);
and
a main controller (<NUM>) for applying a control command to the motor controller (<NUM>) to start or stop operation of the motor (<NUM>)
characterized in that:
the main controller (<NUM>) is configured to control the motor (<NUM>) to stop in response to the result of determining a load state of water and determining whether the level (<NUM>) of water in the outer tub (<NUM>) is zero, based on the current measured by the current sensor (<NUM>) and the rotation speed of the motor (<NUM>) measured by the speed sensor (<NUM>),
wherein the main controller (<NUM>) is further configured to determine that the level (<NUM>) of water in the outer tub (<NUM>) is zero, and control the motor to stop if the rotation speed is increased and the current is reduced, and
wherein the main controller (<NUM>) is configured to count a number of times that the motor (<NUM>) stops, and determine that water is completely drained, based on the level (<NUM>) of water in the outer tub (<NUM>) measured by the water level sensor (<NUM>), if the number of times that the motor (<NUM>) stops is equal to or greater than a reference number.