EP2781640A1

EP2781640A1 - Drum-type washing machine

Info

Publication number: EP2781640A1
Application number: EP12850049.3A
Authority: EP
Inventors: Tomoyuki Kikukawa; Katsuya Wakita; Wataru Uchiyama; Hiroto Nakama
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2011-11-14
Filing date: 2012-11-08
Publication date: 2014-09-24
Also published as: CN103930609A; EP2781640A4; JPWO2013073140A1; WO2013073140A1; CN103930609B

Abstract

A drum-type washing machine according to the present invention includes: a rotary drum which is formed in a bottomed cylindrical shape; a water tub which houses the rotary drum; a water circulation system which causes a circulation pump to circulate washing water in the water tub through a circulation path connected to the water tub; a motor which drives the rotary drum; a load detector which detects a load on the circulation pump; and a controller which controls at least one of a washing step and a rinsing step. Further, when the load detector detects a predetermined change in 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. Consequently, it is possible to prevent bubbles and air from entering the circulation pump, and prevents excessive bubbling or noise from being caused.

Description

TECHNICAL FIELD

The present invention relates to a drum-type washing machine which has means for circulating washing water.

BACKGROUND ART

Conventionally, a drum-type washing machine which has a circulation function of circulating washing water in a water tub by means of a circulation pump is disclosed to enhance washing power (see, for example, Patent Literature 1).
That is, the drum-type washing machine has the circulation pump as a driving source which sprays washing water on clothes in the water tub. The circulation pump is arranged in a circulation path through which washing water circulates, and the circulation pump is operated while a water level detector maintains a predetermined water level. With this configuration, it is possible to increase contacts between a processing target (laundry) and washing water, and efficiently wash the processing target.
However, when most of the laundry loaded in a rotary drum is highly absorbent clothes, the clothes absorb washing water and a water level of washing water in the rotary drum lowers. In this regard, lowering of the water level of the washing water is determined in some cases as a fluctuation of the water level caused when the circulation pump is driven. Hence, the operation of the circulation pump is continued, and bubbles and air enter the circulation pump. As a result, there is a problem that, when bubbles and air enter the circulation pump, excessive bubbling and noise are caused.

Citation List

Patent Literature

PTL 1: Unexamined Japanese Patent Publication No. 2010-36016

SUMMARY OF THE INVENTION

To solve the above problem, a drum-type washing machine according to the present invention includes: a rotary drum which is formed in a bottomed cylindrical shape; a water tub which houses the rotary drum; a water circulation system which causes a circulation pump to circulate washing water in the water tub through a circulation path connected to the water tub; a water supply unit which supplies water into the rotary drum or the water tub; a motor which drives the rotary drum; a load detector which detects a load on the circulation pump; a controller which controls at least one of a washing step and a rinsing step. Further, the controller employs a configuration of, when the load detector detects a predetermined change in load of the circulation pump while the motor and the circulation pump are being driven, stopping driving the motor and stopping a function of the circulation pump.
According to this configuration, even when the water level lowers due to the operation of rotating the rotary drum or driving the circulation pump, even if bubbles and air mix in the circulation pump through the circulation path, it is possible to detect that an output of the circulation pump lowers.
Further, when the load detector detects the predetermined change in load of the circulation pump, the circulation pump is stopped and driving of the motor is stopped. By this means, it is possible to cancel an influence on the fluctuation of the water level caused when the rotary drum is rotated or the circulation pump is driven, recover the water level, and prevent bubbles and air from mixing in the circulation pump through the circulation path. As a result, it is possible to prevent excessive bubbling or noise in the circulation pump caused by the mixed-in bubbles and air.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a schematic structure of a drum-type washing machine according to a first exemplary embodiment of the present invention.
FIG. 2A is a cross-sectional view of a circulation pump of the drum-type washing machine according to the first exemplary embodiment.
FIG. 2B is a side view of the circulation pump of the drum-type washing machine according to the first exemplary embodiment.
FIG. 3 is a circuit diagram of a load detector of the drum-type washing machine according to the first exemplary embodiment.
FIG. 4 is a time chart illustrating an operation of the drum-type washing machine according to the first exemplary embodiment.
FIG. 5 is a time chart illustrating an operation of a drum-type washing machine according to a second exemplary embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of the present invention will be described below with reference to the drawings. In addition, the present exemplary embodiments by no means limit the present invention. Further, in the following exemplary embodiments, washing water includes washing water in a washing step and rinse water in a rinsing step.

(FIRST EXEMPLARY EMBODIMENT)

FIG. 1 is a cross-sectional view illustrating a schematic structure of a drum-type according to a first exemplary embodiment of the present invention.
As illustrated in FIG. 1, the drum-type washing machine according to the present exemplary embodiment has at least water tub 3 which is swingably disposed inside washing machine main body 2, rotary drum 4 which is rotatably disposed in water tub 3, motor 6 which is attached to an outer side of a back surface of water tub 3, water supply system 7, drainage system 8, dry system 9, and water circulation system 16. Rotary drum 4 is driven to rotate by motor 6. In addition, the drum-type washing machine according to the present exemplary embodiment configures a so-called drum-type washing machine which has a function of executing at least a washing step, a rinsing step, a dewatering step and a drying step by automatic control according to mode setting and a control program. In this regard, dry system 9 may be removed.
Further, water supply system 7 adequately supplies water into water tub 3 as indicated by solid arrow A by opening and closing a water supply valve (not illustrated) configured by an electromagnetic valve. In this regard, a detergent in detergent accommodating unit 7a is configured to be adequately loaded in water tub 3 by using supplied water.
Further, drainage system 8 discharges washing water by opening and closing drain valve 19 along a path indicated by dashed-dotted line arrow B when necessary such as upon an end of the washing step or upon the end of the rinsing step. In this regard, the washing water is discharged to an outside of the drum-type washing machine through drainpipe 8a connected to a lower part of water tub 3 and along a path which passes through drainage filter 8b. In addition, drainage filter 8b captures lints and the like, and is configured to be detachable from an outside.
Further, water circulation system 16 circulates the washing water in water tub 3 by driving circulation pump 20 and repeatedly returning the washing water to water tub 3 through the following path, in a washing preparing step, the washing step or the rinsing step, when necessary. In this regard, the path of water circulation system 16 is configured by drainpipe 8a connected to the lower part of water tub 3, drainage filter 8b, inflow side path 31a of circulation path 31 to circulation pump 20, circulation pump 20, and discharge side path 31b of circulation path 31 from circulation path 20. By this means, it is possible to prevent a detergent loaded in water tub 3 from being blended earlier, prevent clothes from leaning to one side and improve functions of the washing step and the rinsing step.
Further, operation panel 21 is provided on a front upper part side of washing machine main body 2, and selection of a mode such as an operation course and various functions is inputted to an input setting unit of operation panel 21. In this regard, controller 22 displays input information on a display unit on operation panel 21 based on the input information of operation panel 21 to notify to a user. Further, when start of an operation is set according to the input from the input setting unit of operation panel 21, controller 22 receives an input of data from water level detector 40 which detects a water level in water tub 3 and starts driving the drum-type washing machine. Furthermore, controller 22 controls operations of the drain valve 19 and the water supply valve, and executes washing by operations such as the washing step, the dewatering step, and the drying step.
Still further, rotary drum 4 and water tub 3 are installed by inclining a rotary shaft direction of rotary shaft 4a downward at, for example, an inclined angle of θ = 20 ± 10 degrees from an opened front surface side (open-close door 5 side), to a back surface side (motor 6 side) with respect to a horizontal direction. In this case, rotary shaft 4a of rotary drum 4 is directly connected to a shaft of motor 6 provided in the back surface of water tub 3. By this means, even when rotary drum 4 is installed at the same height as when rotary shaft 4a of rotary drum 4 is installed in the horizontal direction, openings of water tub 3 and rotary drum 4 are directed obliquely upward. As a result, the user can easily put in and take out the laundry from rotary drum 4 without taking an unnatural posture such as squatting. Further, according to experiences of the inventors of the preset invention, by setting the inclined angle θ to 20 ± 10 degrees, it is possible to provide a state where a user who has a difference in height such as a child (except an infant) to a grown-up or a user of a wheelchair can most easily put in and take out the laundry. Furthermore, even when washing water stored on the back surface side of rotary drum 4 and supplied into rotary drum 4 is a little, it is possible to provide an advantage that a deep stored water state is achieved by inclining rotary drum 4.
Still further, water tub 3 is provided near and along rotary drum 4 while water tub 3 is inclined in the same way as rotary drum 4 in order to cause supplied water to efficiently work on the laundry in rotary drum 4.
Moreover, open-close door 5 is provided to washing machine main body 2 so as to tightly seal opening 13 of water tub 3 via sealing member 14 attached to a rim of open-close door 5, and open opening 13 of water tub 3.
A behavior and an effect of the rotary drum upon a washing operation of the drum-type washing machine according to the present exemplary embodiment will be described below.
First, rotary drum 4 is driven in a forward and reverse arc rotary drive mode and in a forward and reverse continuous rotary drive mode upon a washing operation. Meanwhile, the forward and reverse arc rotary drive mode refers to a drive mode of alternately repeating rapid forward arc rotation of driving rotary drum 4 at 90 degrees or more and 180 degrees or less, and rapid reverse arc rotation. Further, the forward and reverse continuous rotary drive mode refers to a drive mode of alternately repeating forward and reverse continuous rotations of rotary drum 4 at a rotation speed at which the laundry lifted up by rotation of rotary drum 4 makes a behavior of dropping from a height at which the weight of the laundry overweighs.
Furthermore, the forward and reverse arc rotary drive mode and the forward and reverse continuous rotary drive mode of rotary drum 4 are alternately executed in the washing step or in the washing step and the rinsing step. By this means, the laundry is lifted up at 90 degrees or more and 180 degrees or less at maximum due to arc rotation and rapid braking at a rapid speed at 90 degrees or more and 180 degrees or less of rotary drum 4. Further, it is possible to separate the laundry from the inner surface of rotary drum 4 by using the inertia and the weight of the laundry by performing rapid braking at a final stage of lifting up the laundry, and reliably drop the laundry to a side with the left and the right opposite to those of the side on which the laundry is lifted up by using the weight of the laundry. As a result, it is possible to apply a particularly high disentangling function (unraveling function) to the laundry which absorbs washing water, sufficiently swells, loosens and is in a slippery state.
Further, it is possible to apply a mechanical function such as dropping to the laundry and enhance washing performance.
Furthermore, according to the forward and reverse arc rotary drive mode of alternately repeating rapid forward arc rotation in a forward direction and rapid reverse arc rotation in a reverse direction of arc rotary drive, it is possible to alternately switch the left and the right of a lift-up position and a drop position of the laundry by alternate forward and reverse rapid arc rotary drive per arc rotary drive. Consequently, it is possible to more effectively prevent the laundry from entangling, and further enhance the disentangling function. Further, it is possible to enhance the washing performance by increasing the number of times to apply the mechanical function such as dropping to the laundry.
Furthermore, according to the high disentangling function, it is possible to prevent entanglement of the laundry caused when the washing step and the rinsing step proceed. As a result, it is possible to continuously execute effective beat washing in the forward and reverse arc rotary mode, and enhance a washing effect and a rinsing effect.
In addition, although it is possible to reduce entanglement, twists and wrinkles of the laundry only in the forward and reverse arc rotary drive mode, a position of the laundry in upper and lower directions is hardly switched and the laundry at the bottom part of rotary drum 4 hardly moves, and therefore uneven washing is likely to occur. Hence, the position of the laundry in the upper and lower directions is switched by using the forward and reverse arc rotary drive mode and the forward and reverse continuous rotary drive mode in combination. Consequently, it is possible to reduce entanglement, twists and wrinkles of the laundry in the forward and reverse continuous rotary drive mode, and reduce an unbalance caused when a mechanical function is applied to the laundry in the forward and reverse arc rotary drive mode. As a result, it is possible to achieve a behavior of stable hand washing while reducing entanglement, twists and wrinkles of the laundry in the forward and reverse arc rotary drive mode. Further, it is possible to achieve an even washing behavior which washes the laundry while reducing uneven washing by continuously moving the laundry in the forward and reverse continuous rotary drive mode and which is effective with respect to stubborn stains.
Water circulation system 16 of the drum-type washing machine according to the present exemplary embodiment will be described below with reference to FIG. 1, and Figs. 2A and 2B.
FIG. 2A is a cross-sectional view of the circulation pump of the drum-type washing machine according to the present exemplary embodiment. FIG. 2B is a side view of the circulation pump of the drum-type washing machine according to the present exemplary embodiment.
First, as illustrated in FIG. 1, circulation pump 20 is fixed and disposed on base plate 2a which is the bottom part of washing machine main body 2.
Further, as illustrated in Figs. 2A and 2B, circulation pump 20 is configured by resin pump casing 20b which accommodates impeller 20a fitted to resin mounting seat 35, and metal motor casing 20d of circulation motor 20c. In this regard, an opening side of pump casing 20b is fitted to mounting seat 35 such that the opening side is in contact with and integrated with bearing partition wall 20d1 at a front end of motor casing 20d. By this means, impeller 20a is directly connected to motor shaft 20e of circulation motor 20c. Further, circulation pump 20 is fixed to base plate 2a of washing machine main body 2 by, for example, bolts through mounting pieces 35a of attachment base 35.
Furthermore, discharge side path 31b of circulation path 31 connected to drainage connector 20g of circulation pump 20 is connected, from the outer surface side, to spray port 51 provided at the lowermost part of front end wall 3h around opening 13 of water tub 3 as illustrated in FIG. 1. Still further, as indicated by arrow a in FIG. 1, washing water from discharge side path 31b is sprayed between the back surface of front end wall 3h of water tub 3 and the top surface of front end wall 4b of rotary drum 4 corresponding to front end wall 3h. By this means, washing water is discharged in rotary drum 4 by circulation pump 20 through flow path 52 formed between the back surface of front end wall 3h of water tub 3 and the top surface of front end wall 4b of rotary drum 4. Meanwhile, inflow connector 20f of circulation pump 20 is connected to inflow side path 31a of circulation path 31, and the washing water in water tub 3 is poured in circulation pump 20 through drainpipe 8a provided at the lower part of water tub 3 by the driving of circulation pump 20.
Circulation pump 20 of water circulation system 16 configured as described above is controlled by controller 22 described below. In this regard, controller 22 controls circulation pump 20 by means of current detector 30 which is described below with reference to FIG. 3, current detector 30 being a load detector which detects a change in load of circulation motor 20c.
A method of controlling circulation motor 20c of circulation pump 20 will be described below with reference to Figs. 3 and 4.
FIG. 3 is a circuit diagram for explaining the load detector of the drum-type washing machine according to the first exemplary embodiment of the present invention. FIG. 4 is a time chart illustrating an operation of the drum-type washing machine according to the first exemplary embodiment of the present invention.
That is, as illustrated in FIG. 3, controller 22 has current detector 30 that measures a change in load of circulation motor 20c of circulation pump 20 as a drive current value or a drive power amount of circulation motor 20c in at least the washing step. In this regard, a control method of controlling circulation motor 20c which is generally used in recent years as current detector 30 by way of inverter control is applied and used. In addition, the drive current value of circulation motor 20c will be described below as an example of the change in load of circulation motor 20c.
Further, as described below with reference to FIG. 4, value W of a load on circulation motor 20c measured by current detector 30 and value WO of an initial load on circulation motor 20c in the washing step are compared with each other to detect a change in load of circulation motor 20c. In addition, a value obtained by calculating a time average when the number of rotations of circulation motor 20c is in a stationary state is preferably used as value WO of the initial load on circulation motor 20c. However, the value is not limited to this, and only needs to enable detection of a change in load.
First, the load detector which detects the change in load of circulation motor 20c of circulation pump 20 will be described with reference to FIG. 3.
As illustrated in FIG. 3, circulation motor 20c is driven by controller 22 which controls inverter circuit 27 based on signals from alternating-current power source 25, rectifier circuit 26, inverter circuit 27, and load detector 30. Rectifier circuit 26 converts alternating-current power from alternating-current power source 25 into direct-current power. Meanwhile, rectifier circuit 26 is configured by full-wave rectifier circuit 28 and a direct-current voltage doubler circuit. The direct-current voltage doubler circuit is configured by connecting capacitors 29a and 29b connected in series to a direct-current output terminal of full-wave rectifier circuit 28 and a connection point of capacitors 29a and 29b to one terminal of inputs of the alternating-current power source, and increases a voltage applied to inverter circuit 27. Inverter circuit 27 drives circulation motor 20c by converting the direct-current power converted by rectifier circuit 26 into three-phase alternating-current powers. The current detector which is load detector 30 is connected to a negative voltage side of inverter circuit 27, and detects currents flowing in lower arms of three phases of a U phase, a V phase, and a W phase of inverter circuit 27 by, for example, measuring voltages at both ends of a resistor. By this means, it is possible to detect an output current of inverter circuit 27, that is, a drive current value which is a phase current supplied to the U phase, the V phase, and the W phase of circulation motor 20c.
Further, controller 22 controls driving and rotation of circulation motor 20c by computing the drive current value of inverter circuit 27 based on the output signal of current detector 30, and applying a predetermined frequency or a predetermined voltage matching the set number of rotations. In this regard, by controlling circulation motor 20c to provide a drive current phase or a reactive current with respect to the output voltage outputted to each phase of inverter circuit 27 according to the load on circulation motor 20c, it is possible to drive and rotate circulation motor 20c at a set synchronous speed (the set number of rotations).
That is, it is possible to detect a load state of circulation motor 20c at all times by using above current detector 30.
An operation of executing the washing step by driving rotary drum 4 and circulation pump 20 will be described below with reference to FIG. 1 and FIG. 4.
First, the user puts the laundry in rotary drum 4, and operates operation panel 21 and starts the operation. By this means, controller 22 opens the electromagnetic valve of water supply system 7, and then water which is washing water is supplied into water tub 3.
Next, when water level detector 40 which is provided on a lower side of the back surface of water tub 3 detects that water is supplied to a predetermined water level, controller 22 closes the electromagnetic valve, stops water supply and starts rotating rotary drum 4. In this case, controller 22 drives circulation pump 20 while rotating rotary drum 4. By this means, it is possible to increase a contact time of the laundry and the washing water, and enhance washing performance.
However, when rotary drum 4 is rotated and circulation pump 20 is driven, the water level in water tub 3 lowers. Further, when there are a lot of highly absorbent fibers among the laundry such as cotton in rotary drum 4, the water level in water tub 3 lowers. Furthermore, when the laundry clothes absorb water and therefore the water level of washing water lowers too much, beat washing performance for the laundry lowers.
However, even if water level detector 40 detects the water level in water tub 3, it is difficult to determine whether the water level is fluctuated because rotary drum 4 is rotated and circulation pump 20 is driven or the water level lowers because the laundry clothes absorb water. Hence, when bubbles and air mix in circulation path 31 and enter circulation pump 20 in a state where the water level in water tub 3 cannot be accurately detected, an output to circulate the washing water in circulation pump 20 lowers. Further, when bubbles and air mix in circulation pump 20, circulation pump 20 causes excessive bubbling or noise in some cases.
Meanwhile, when circulation pump 20 is driven in a state where the amount of water in water tub 3 decreases and the water level lowers, circulation pump 20 is operated while the air mixes in circulation pump 20, that is, circulation pump 20 is driven in an air entrainment state.
Further, when circulation pump 20 is driven in the air entrainment state, the load on circulation pump 20 decreases as illustrated in FIG. 4, and therefore the load on circulation motor 20c also decreases. That is, it is possible to detect a state of circulation pump 20 based on the change in load of circulation motor 20c.
Hence, in the present exemplary embodiment, when the water level in the water tub significantly lowers and more air mixes in, air entrainment of circulation pump 20 is detected by using change in load of circulation motor 20c.
More specifically, as illustrated in FIG. 4, predetermined threshold Wd is set to a load on circulation motor 20c detected by the load detector. Further, when the load on circulation motor 20c is smaller than predetermined threshold Wd and change in load A which is (WO - Wd) or more compared to value WO of the load on circulation motor 20c in the stationary state, it is determined that circulation pump 20 causes air entrainment.
Furthermore, when current detector 30 detects air entrainment of circulation pump 20 as the change in load of circulation motor 20c, controller 22 controls the number of rotations of circulation motor 20c to stop the function of circulation pump 20. More specifically, rotation of circulation motor 20c is stopped or circulation motor 20c is driven by lowering the number of rotations to such a degree that circulation pump 20 cannot function. Further, the function of circulation pump 20 is stopped to prevent in advance the water level in water tub 3 from lowering or prevent bubbles and air from mixing in circulation path 31 and entering circulation pump 20. Consequently, it is possible to prevent excessive bubbling caused upon breakup of bubbles and air mixing in circulation pump 20, and noise caused upon breakup.
Next, controller 22 stops driving motor 6, and stops rotating rotary drum 4.
Next, while rotation of rotary drum 4 is stopped and in a state where the water level is stabilized by stopping driving circulation pump 20, water level detector 40 detects the water level in water tub 3. Further, when water level detector 40 detects that the water level is the predetermined water level or more, driving of rotary drum 4 and circulation pump 20 is started again. In this regard, when lowering of the water level in water tub 3 is caused when rotary drum 4 is rotated or circulation pump 20 is driven, washing water in the clothes and water tub 3 is reflected to the water level while rotation of rotary drum 4 is stopped and driving of circulation pump 20 is stopped, and the water level in water tub 3 is recovered. Hence, even when circulation pump 20 is driven again, the water level is recovered, so that bubbles and air are prevented from mixing in circulation path 31. As a result, it is possible to prevent lowering of an output of circulation pump 20, excessive bubbling and noise caused upon breakup.
Meanwhile, when water level detector 40 detects that the water level does not satisfy the predetermined water level, controller 22 determines that the laundry absorbs water and therefore the water level in water tub 3 lowers. Then, controller 22 opens the electromagnetic valve of water supply system 7, and supplies water to the predetermined water level in water tub 3 again. Subsequently, controller 22 drives motor 6, rotates rotary drum 4 and further drives circulation pump 20. As a result, it is possible to prevent excessive bubbling or noise of circulation pump 20, and execute the washing step without lowering the washing performance.
As described above, according to the present exemplary embodiment, current detector 30 detects a predetermined change in load of circulation motor 20c of circulation pump 20, so that, during the operation of circulation pump 20, it is possible to detect at all times based on the change in load of circulation motor 20c that bubbles and air mix in circulation pump 20. As a result, it is possible to prevent excessive bubbling caused upon breakup of bubbles and air mixing in circulation pump 20, or noise caused upon breakup by stopping driving circulation pump 20.
Further, by stopping driving circulation pump 20, washing water returns to the clothes and the water tub and is reflected to the water level in water tub 3, and the water level is recovered. Consequently, when circulation pump 20 is activated again, it is possible to prevent bubbles and air from mixing in the circulation path. As a result, it is possible to prevent lowering of an output of circulation pump 20, excessive bubbling and noise caused upon breakup of air.

(SECOND EXEMPLARY EMBODIMENT)

A drum-type washing machine according to a second exemplary embodiment of the present invention will be described below with reference to FIG. 5.
FIG. 5 is a time chart illustrating an operation of the drum-type washing machine according to the second exemplary embodiment of the present invention.
Further, as illustrated in FIG. 5, the drum-type washing machine according to the present exemplary embodiment differs from that of the first exemplary embodiment in stopping driving a motor and a function of a circulation pump, and detecting and controlling a water level by means of a water level detector after a predetermined time passes. The other configurations and operations are the same as those of the first exemplary embodiment, and will be described by employing the components and the operations of the first exemplary embodiment. By this means, it is possible to prevent error detection.
That is, as illustrated in FIG. 5, the drum-type washing machine according to the present exemplary embodiment detects value W of a change in load of circulation motor 20c as a drive current value by means of load detector 30 while rotary drum 4 and circulation pump 20 are driven. Further, when a load of circulation motor 20c is smaller than predetermined threshold Wd and load detector 30 detects the change in load A which is (WO - Wd) or more compared to value WO of the load on circulation motor 20c in a stationary state, a function of circulation pump 20 is stopped, that is, the number of rotations of circulation pump 20 is lowered or circulation pump 20 is stopped.
Next, controller 22 stops driving motor 6 and stops rotating rotary drum 4.
Next, the function of circulation pump 20 is stopped and controller 22 detects a water level in water tub 3 by means of water level detector 40 after predetermined time t1 has passed, in order to avoid error detection of load detector 30. In this case, when the detected water level is a predetermined water level or less, it is determined that the amount of water absorbed by clothes is great depending on a material and thus the water level lowers, and therefore bubbles and air mix in circulation path 31. In this case, controller 22 executes the washing step again after opening an electromagnetic valve of water supply system 7 and supplying water to a predetermined water level or supplying water for a predetermined time. By this means, the water level of washing water is detected after circulation pump 20 is stopped and predetermined time t1 passes, so that it is possible to accurately detect the water level in water tub 3. As a result, it is possible to supply an adequate amount of water according to the amount of water absorbed by clothes, the amount differing depending on a material, thereby washing the laundry with stable and high washing power.
In addition, although an example has been described with each of the above embodiments where a circulation pump is controlled based on a change in load of a circulation motor in the washing step, the present invention is not limited to this. For example, the circulation pump may be controlled in the rinsing step. By this means, it is possible to further enhance rinsing performance.
Further, although an example has been described with each of the above embodiments where a load detector detects a change in load as a drive current value of a circulation motor, the present invention is not limited to this. When, for example, driving is performed according to a driving method such as constant power amount control by using the circulation pump which is driven by inverter control, the load detector may detect and control a change in load such as a drive power amount or the number of rotations of the circulation motor. By this means, it is possible to provide the same effect.
Further, although an example has been described with each of the above embodiments where the load detector detects three-phase drive current values of the circulation motor, the present invention is not limited to this. For example, the load detector may be configured to detect one-phase or two-phase drive current values of three-phases of the circulation motor. By this means, it is possible to simplify the configuration of the load detector.
Further, although an example has been described with each of the above embodiments where a drive current value of the circulation motor is detected according to voltages at both ends of the resistor, the present invention is not limited to this. For example, a current sensor which is required for inverter drive may be configured to detect a drive current value. By this means, it is possible to achieve a low-cost and compact load detector.
As described above, a drum-type washing machine according to the present invention includes: a rotary drum which is formed in a bottomed cylindrical shape; a water tub which houses the rotary drum; a water circulation system which causes a circulation pump to circulate washing water in the water tub through a circulation path connected to the water tub; a water supply unit which supplies water into the rotary drum or the water tub; a motor which drives the rotary drum; a load detector which detects a load on the circulation pump; and a controller which controls at least one of a washing step and a rinsing step. Further, the controller is configured to, when the load detector detects a predetermined change in load of the circulation pump while the motor and the circulation pump are being driven, stop driving the motor and stop a function of the circulation pump.
According to this configuration, it is possible to prevent lowering of a water level in a water tub caused when the rotary drum is rotated, the circulation pump is driven or the laundry absorbs water, and prevent bubbles and air from mixing in the circulation path and entering the circulation pump. As a result, it is possible to prevent excessive bubbling in the circulation pump caused by the mixed-in bubbles and air, or noise caused upon breakup of air. Further, when the water level in the water tub lowers, washing water in clothes or the water tub is reflected to the water level and recovered while driving of the rotary drum and the function of the circulation pump are stopped. Consequently, even when the circulation pump is activated again, the water level is recovered, so that it is possible to prevent bubbles and air from mixing in the circulation path. By this means, it is possible to prevent lowering of an output of the circulation pump caused by air entrainment, and prevent lowering of washing power of the drum-type washing machine.
Further, the drum-type washing machine according to the present invention further has a water level detector which detects a water level of washing water, and the controller employs a configuration in which, when the water level detected by the water level detector is a predetermined water level or less after driving of the motor and a function of the circulation pump are stopped, the circulation pump is driven after the water supply unit supplies the additional amount of water.
According to this configuration, even when the water level lowers due to a great amount of water absorbed by clothes, it is possible to detect that bubbles and air mix in the circulation path by means of the load detector and the water level detector, thereby supplying the additional amount of water. Consequently, it is possible to stabilize the output of the circulation pump, and prevent excessive bubbling and noise caused upon breakup. Further, the output of the circulation pump is stabilized, so that it is possible to stably circulate washing water and pour the washing water on the laundry. As a result, it is possible to realize the drum-type washing machine which can further enhance washing performance and rinsing performance.
Further, the load detector of the drum-type washing machine according to the present invention employs a configuration of detecting a drive current value of the circulation motor of the circulation pump. According to this configuration, particularly when a circulation pump driven by an inverter is used, a current sensor which is required for inverter drive can configure the load detector. Consequently, it is possible to achieve a low-cost load detector.
Further, the load detector of the drum-type washing machine according to the present invention is configured to detect a drive power amount of the circulation motor of the circulation pump. According to this configuration, it is possible to use and drive the circulation pump driven by inverter control according to a driving method such as constant power amount control. As a result, it is possible to easily detect a change in load by means of the load detector and enhance precision.

INDUSTRIAL APPLICABILITY

A drum-type washing machine according to the present invention is useful in a technical field of a drum-type washing machine which prevents lowering of an output of a circulation pump, and washes the laundry accommodated in a rotary drum with high washing performance.

REFERENCE MARKS IN THE DRAWINGS

2: washing machine main body
2a: base plate
3: water tub
3h: front end wall
4: rotary drum
4a: rotary shaft
4b: front end wall
5: open-close door
6: motor
7: water supply system
7a: detergent accommodating unit
8: drainage system
8a: drainpipe
8b: drainage filter
9: dry system
13: opening
14: sealing member
16: water circulation system
19: drain valve
20: circulation pump
20a: impeller
20b: pump casing
20c: circulation motor
20d: motor casing
20d1: bearing partition wall
20e: motor shaft
20f: inflow connector
20g: drainage connector
21: operation panel
22: controller
25: alternating-current source
26: rectifier circuit
27: inverter circuit
28: full-wave rectifier circuit
29a: capacitor
30: current detector (load detector)
31: circulation path
31a: inflow side path
31b: discharge side path
35: mounting seat
35a: mounting piece
40: water level detector
51: spray port
52: flow path

Claims

A drum-type washing machine comprising:
a rotary drum which is formed in a bottomed cylindrical shape;

a water tub which houses the rotary drum;

a water circulation system which causes a circulation pump to circulate washing water in the water tub through a circulation path connected to the water tub;

a water supply unit which supplies water into the rotary drum or the water tub;

a motor which drives the rotary drum;

a load detector which detects a load on the circulation pump; and

a controller which controls at least one of a washing step and a rinsing step,

wherein, when the load detector detects a predetermined change in 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.
The drum-type washing machine according to claim 1, further comprising a water level detector which detects a water level of the washing water,
wherein, when the water level detected by the water level detector is a predetermined water level or less after driving of the motor and the function of the circulation pump are stopped and a predetermined time passes, the controller drives the circulation pump after the water supply unit supplies an additional amount of water.
The drum-type washing machine according to any one of claims 1 and 2, wherein the load detector detects a drive current value of a circulation motor of the circulation pump.
The drum-type washing machine according to any one of claims 1 and 2, wherein the load detector detects a drive power amount of a circulation motor of the circulation pump.