Washing machine

Abstract

To provide a washing machine capable of appropriately improving an unbalanced state according to a state of contents in a washing tub.SOLUTION: A washing machine comprises a washing tub for accommodating contents, a water supply valve for supplying water to the washing tub, a drain valve for draining water from the washing tub, an offset detection unit for detecting offset of the contents in the washing tub, a control unit for controlling opening and closing of the drain valve based on a detection result by the offset detection unit, and a water level sensor for detecting a water level in the washing tub, wherein the control unit stops dehydration and closes the drain valve when the offset detection unit detects offset of the contents, and opens the drain valve and restarts dehydration when an amount of change in the water level detected within a predetermined time in a state where the drain valve is closed is less than a specified amount.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The following disclosure relates to a washing machine.

Background Art

[0002] Patent Document 1 discloses a dehydration motion control method for a washing machine that, when an imbalance of the rotary tub is detected during the dehydration operation, repeats the operations of stopping and restarting the rotation of the rotary tub a predetermined number of times, and further, when an imbalance is detected, performs an imbalance correction process such as water supply to the rotary tub and agitation motion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a washing machine that can appropriately improve an unbalanced state according to the state of the contents in the washing tub.

Means for Solving the Problems

[0005] The washing machine of the present disclosure includes a washing tub that houses the contents, a water supply valve that supplies water to the washing tub, a drain valve that discharges water from the washing tub, a deviation detection unit that detects the deviation of the contents in the washing tub, a control unit that controls the opening and closing of the drain valve based on the detection result of the deviation detection unit, and a water level sensor that detects the water level in the washing tub. When the deviation detection unit detects the deviation of the contents, the control unit stops the dehydration and closes the drain valve, and when the amount of change in the water level detected within a predetermined time in the state where the drain valve is closed is less than a specified amount, the control unit opens the drain valve and resumes the dehydration.

Effects of the Invention

[0006] According to the present disclosure, it is possible to provide a washing machine that can appropriately improve an unbalanced state according to the state of the contents in the washing tub.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments of a washing machine and the like according to the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the content described in the following embodiments, and design changes can be appropriately made within the scope that satisfies the configuration of the present disclosure. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Hereinafter, the description will be centered on the main parts and the parts related to the present disclosure.

[0009] In the present disclosure, the "washing machine" generally means all devices that perform various processes such as washing on the laundry. Examples of the processing of the laundry include, for example, washing, drying, deodorizing, sterilizing, and the like. The laundry is not particularly limited. Examples of the laundry include, for example, fabric products. Specific examples of the laundry include, for example, clothing such as clothes, hats, and gloves; belongings such as shoes, bags, handkerchiefs, and towels; curtains; bedding such as blankets, bath mats, and futon covers; carpets; stuffed toys; and the like.

[0010] The "vertical washing machine" refers to a washing machine in which the rotation axis of the tub extends substantially along the vertical direction in the installed state.

[0011] (Embodiment 1) FIG. 1 is a perspective view schematically showing the appearance of the washing machine 1. FIG. 2 is a cross-sectional view schematically showing the internal structure of the washing machine 1. FIG. 3 is a block diagram of the washing machine 1. As shown in FIG. 1, the washing machine 1 is preferably a vertical washing machine. The configuration of the washing machine 1 includes a housing 10, a lid 11 disposed on the upper part of the housing 10, and an operation display unit 12.

[0012] The housing 10 is formed of, for example, metal or synthetic resin and is substantially rectangular in plan view. Usually, the washing machine 1 further includes a lid 11, and the housing 10 has an opening inside the lid 11. The lid 11 opens or closes the opening. The lid 11 is maintained openable and closable by, for example, a hinge (also referred to as a hinge). With the lid 11 open, laundry is put into the washing tub 13 through the opening. The operation display unit 12 displays various information and receives operations from the user.

[0013] As shown in FIG. 2, the washing machine 1 has, inside the housing 10, a washing tub 13 for accommodating contents such as laundry, an outer tub 14 disposed outside the washing tub 13, a drive unit 20, a water supply unit 30, a drainage unit 40, a water level sensor 60, and various functional units. Examples of the various functional units include the offset detection unit 50 and the capacity determination unit 70 shown in FIG. 3.

[0014] The washing tub 13, also referred to as an inner tub, is disposed inside the outer tub 14. Each of the washing tub 13 and the outer tub 14 has a bottomed cylindrical shape with one end (preferably the upper end) of the cylindrical body open. Examples of the bottomed cylindrical shape include a bottomed cylindrical shape and a bottomed rectangular cylindrical shape. Further, each of the washing tub 13 and the outer tub 14 has a bottom opening at a substantially central portion of the bottom surface. The bottom opening penetrates the lower portions of the washing tub 13 and the outer tub 14 and can function as a drainage unit for draining the water inside the washing tub 13 and the outer tub 14.

[0015] The washing tub 13 may be a washing tub (also referred to as a tub with holes) having holes provided in the side wall (peripheral surface) of the washing tub 13 for water to enter and exit between the washing tub 13 and the outer tub 14. Further, the washing tub 13 may be a washing tub (also referred to as a tub without holes) having no holes provided in the side wall of the washing tub 13 for water to enter and exit between the washing tub 13 and the outer tub 14. In FIG. 2, the case where the washing tub 13 is a tub without holes is illustrated. The tub without holes can store water by itself. The tub without holes may have holes or the like provided in the side wall for discharging water that jumps out from the upper part of the washing tub during dehydration in addition to the bottom opening. However, it is preferable that there are no holes provided for water to enter and exit between the outer tub 14 at a position below the maximum water level during the washing process or the rinsing process. Since the tub without holes drains water concentratedly from one bottom opening provided at the bottom, even if the amount of water draining from the laundry is small, the change amount of the water level can be detected by a water level sensor or the like. Therefore, it is suitable as a washing tub used in the washing machine of the present disclosure. A balancer (weight) may be arranged at the upper part of the washing tub.

[0016] The drive unit 20 includes a drive motor, a clutch-brake mechanism, a drive shaft, a stirring member 21, etc., and rotates the washing tub 13. The stirring member 21 (also referred to as a pulsator) is a member for stirring the laundry accommodated in the washing tub 13 and is arranged at the bottom of the washing tub 13. The stirring member 21 rotates or swings independently of the washing tub 13 by the drive of the drive motor via the drive shaft. The drive shaft is inserted through the bottom opening (i.e., the drainage path) of the washing tub 13. The drive motor and the clutch-brake mechanism drive the washing tub 13 and the stirring member 21 based on an instruction from the control unit 100, for example. The drive motor is, for example, a DC (direct current) motor unit and can switch the rotation direction in both the forward and reverse directions. The drive shaft has a double-shaft structure of a stirring shaft and a dehydration shaft. The stirring shaft is connected to the stirring member 21 and rotates the stirring member 21. The dehydration shaft is connected to the washing tub 13 and rotates the washing tub 13.

[0017] The water supply section 30 includes a water supply pipe 32 connected to a water source such as a faucet of a water supply system, and a water supply valve 31 for opening and closing the water supply pipe 32. The drainage section 40 includes a drainage channel and a drainage valve 41 for opening and closing the drainage channel. The opening and closing of the water supply valve 31 and the drainage valve 41 are controlled by the control section 100. When the water supply valve 31 is opened, water is supplied to the washing tub 13, and when the drainage valve 41 is opened, water is discharged from the washing tub 13. Examples of the water supply valve 31 and the drainage valve 41 include electromagnetic valves.

[0018] When the washing tub 13 is a tub without holes, as shown in FIG. 2, the drainage channel may include, for example, an inner tub drainage channel 42 for discharging the water accumulated in the washing tub 13, an outer tub drainage channel 43 for discharging the water accumulated in the outer tub 14, and an external drainage channel 44 for guiding the water discharged from the inner tub drainage channel 42 and the outer tub drainage channel 43 to the outside of the machine. When the washing tub 13 is a tub without holes, the drainage valve 41 is preferably disposed upstream (on the side of the washing tub 13) of the point where the inner tub drainage channel 42 and the outer tub drainage channel 43 merge. When the washing tub 13 is a tub with holes, it is not necessary to separate the drainage channel for discharging the water accumulated in the inner tub drainage channel 42 and the drainage channel for discharging the water accumulated in the outer tub drainage channel 43.

[0019] The water level sensor 60 detects the water level in the washing tub 13. The arrangement position of the water level sensor 60 is not particularly limited as long as it can detect the water level in the washing tub 13. Ordinary washing machines are equipped with a water level sensor to detect the water level of the water supplied into the washing tub. By using such a water level sensor, it is possible to estimate the amount of water drained from the laundry without adding a sensor for detecting a change in the center of gravity of the contents in the washing tub newly. Examples of the water level sensor include a diaphragm type (pressure type) water level sensor. The water level sensor may be connected to a tube 61. One end of the tube 61 is connected to the water level sensor, and the other end may be connected, for example, between the bottom opening of the washing tub 13 and the drain valve 41. Air is contained in the tube 61. When water drains from the laundry with the drain valve 41 closed, the pressure in the tube 61 connected to the drainage path connected to the washing tub 13 increases, and that pressure is detected by the water level sensor. The more water drains from the laundry, the higher the water level detected by the water level sensor. The water level sensor 60 may detect the water level of the water accumulated in the washing tub 13, or a liquid reservoir for accumulating water may be arranged upstream of the drain valve 41 (on the washing tub 13 side), and the water level of the water accumulated in the liquid reservoir may be detected.

[0020] The unbalance detection unit 50 detects the unbalance of the contents in the washing tub 13. The unbalance detection unit 50 only needs to be able to detect the presence or absence of unbalance of the contents such as the laundry in the washing tub 13. Examples thereof include a camera, a weight sensor, or a vibration sensor. In this specification, the unbalance of the contents in the washing tub 13 is also referred to as imbalance. The above-mentioned contents is a concept including not only the laundry itself but also the laundry containing water.

[0021] The capacity determination unit 70 measures the capacity of the laundry put into the washing tub 13. The capacity determination unit 70 may determine the capacity of the laundry based on, for example, the result of detecting the current or the driving rotation speed of the driving motor of the driving unit 20 by rotating the washing tub 13 with the laundry accommodated in the washing tub 13. Further, the capacity determination unit 70 may be a weight sensor, and may measure the weight of the laundry put into the washing tub 13 and determine the capacity of the laundry.

[0022] The control unit 100 is composed of a CPU, an MPU, etc., and executes a program stored in a storage device that can be provided inside or outside the washing machine 1. The control unit 100 may be a microcomputer including a CPU and a storage device, etc. Note that, as will be described later, at least a part of the processing performed by the control unit 100 may be performed outside the washing machine 1 (for example, a server capable of communicating with the washing machine 1).

[0023] The control unit 100 performs calculations and various processes based on, for example, operation instructions for the washing machine 1 acquired from the operation display unit 12, measurement values acquired from each member, determination results, etc. The operation instruction for the washing machine 1 is an instruction from a user or the like regarding, for example, setting or changing operation start (operation ON), operation stop (operation OFF), operation type (for example, washing, drying, tub cleaning, deodorization, etc.), operation mode (for example, standard mode, urgent mode, dry mode, etc.), operation time, etc.

[0024] The processing executed by the control unit 100 will be described below. In the washing machine 1, a series of washing processes such as washing, rinsing, and dehydration are usually performed. When the laundry is put into the washing tub 13 and the control unit 100 acquires an operation instruction from the operation display unit 12, the control unit 100 closes the drain valve 41, opens the water supply valve 31, and performs processes such as detergent input. When a predetermined amount of water accumulates in the washing tub 13, the control unit 100 closes the water supply valve 31 and drives the drive unit 20 in a state where water has accumulated in the washing tub 13, and rotates either one or both of the washing tub 13 and the stirring member 21 to perform the washing process. When the washing process ends, the rinsing process is performed. In the rinsing process, the control unit 100 opens the drain valve 41 to drain water from the washing tub, drives the drive unit 20 to dehydrate, then closes the drain valve 41 and opens the water supply valve 31. When a predetermined amount of water accumulates in the washing tub, the control unit 100 closes the water supply valve 31 and drives the drive unit 20 in a state where water has accumulated in the washing tub. Then, the control unit 100 opens the drain valve 41 to drain water from the washing tub and ends the rinsing process.

[0025] FIG. 4 is a flowchart showing a preferred example of the processing by the control unit 100 in Embodiment 1. In FIG. 4, the dehydration process after the rinsing process will be described. When the rinsing process ends, the control unit 100 opens the drain valve 41 (step S1) and rotates the washing tub 13 to start dehydration (step S2). Note that usually, since the drain valve 41 is open at the end of the rinsing process, in step S1, the control unit 100 may maintain the drain valve 41 in the open state. The time when the washing tub 13 starts to rotate with the drain valve 41 open is defined as the dehydration start time.

[0026] When dehydration starts, the unbalance detection unit 50 detects the vibration of the washing tub 13 and the unbalance of the weight of the contents, and outputs the detection result to the control unit 100. The control unit 100 controls the opening and closing of the drain valve 41 based on the detection result by the unbalance detection unit 50. Specifically, the control unit 100 determines the presence or absence of unbalance of the contents in the washing tub 13 based on the detection result input from the unbalance detection unit 50 (step S3). Note that the unbalance detection unit 50 may determine the presence or absence of unbalance of the contents in the washing tub 13 based on its own detection result, output the determination result to the control unit 100, and the control unit 100 may control the opening and closing of the drain valve 41 based on the determination result input from the unbalance detection unit 50.

[0027] In step S3, when no unbalance (unevenness) of the contents is detected, that is, when the determination result is "NO", the control unit 100 continues dehydration (step S4). The control unit 100 measures the dehydration time (step S5). When the dehydration time reaches the set time, that is, if the determination result in step S5 is "YES", the control unit 100 stops dehydration (step S6), closes the drain valve 41 (step S7), and ends a series of washing processes (END). The above dehydration time refers to the time from when the rotation of the washing tub 13 starts with the drain valve 41 open as the start time until the rotation speed of the washing tub 13 is maintained at a high speed of about 900 rpm.

[0028] If the dehydration time does not reach the set time in step S5, that is, if the determination result is "NO", the process returns to step S3, and the control unit 100 continues to determine whether there is unevenness of the contents in the washing tub 13.

[0029] In step S3, if unevenness (unbalance) of the contents is detected, that is, if the determination result is "YES", the control unit 100 stops the rotation of the washing tub 13 to stop dehydration (step S8) and closes the drain valve 41 (step S9). Then, the control unit 100 causes the water level sensor 60 to detect the water level in the washing tub 13 for a predetermined time with the drain valve 41 closed (step S10). The above-mentioned predetermined time is preferably, for example, 20 seconds or more and 5 minutes or less, and more preferably 1 minute or more and 3 minutes or less. The start time of the above-mentioned predetermined time refers to the time when the drain valve 41 is closed.

[0030] The water level sensor 60 receives an instruction from the control unit 100, detects the water level in the washing tub 13 with the drain valve 41 closed, and outputs the detection value to the control unit 100. The water level sensor 60 may detect the water level in the washing tub 13 at at least two points, that is, at the start time of the predetermined time (i.e., the time when the drain valve 41 is closed) and at the end time of the predetermined time, but may also continuously detect the water level in the washing tub 13 during the predetermined time. The control unit 100 calculates ΔH based on the detection value obtained from the water level sensor 60 and determines whether ΔH is equal to or greater than a specified amount (step S11).

[0031] The above-mentioned ΔH is obtained by [(water level detected by the water level sensor 60 at the end of the predetermined time - water level detected by the water level sensor 60 at the start of the predetermined time) / predetermined time]. The above-mentioned ΔH is preferably, for example, 3 mm / 1 minute or more in the case of a tub without holes. In the case where the washing tub 13 has holes, since the water spreads over the entire bottom of the tub, it is necessary to set a longer predetermined time to promote the water level change.

[0032] Since the laundry after the rinsing process contains a large amount of water, over time, the water contained in the laundry may drain out, or as the water drains out, the laundry stuck to the upper part of the side of the washing tub 13 may fall to the bottom of the washing tub 13 due to its own weight, causing the center of gravity of the contents in the washing tub 13 to move downward, and the unbalanced state may naturally be eliminated. In the present disclosure, the change in the center of gravity of the contents in the washing tub is captured by the change amount ΔH of the water level discharged from the washing tub 13 within a predetermined time with the drain valve 41 closed. The above-mentioned predetermined time means the time from the point when the drain valve 41 is closed as the start of the predetermined time to the point in time (end) after the elapse of the predetermined time from the start time. In general, the dehydration process is performed with the drain valve 41 open, and the water discharged from the washing tub is directly discharged outside the washing machine. Therefore, in a conventional washing machine, usually, the amount of water discharged from the laundry or the washing tub during the dehydration process is not measured.

[0033] If ΔH detected in step S11 is less than the specified amount, the amount of water draining out of the laundry is small, and it is considered that there is little possibility that the center of gravity in the washing tub 13 will change even if more time is allowed for water drainage from the laundry. Therefore, when the change amount of the water level discharged from the washing tub 13 within a predetermined time with the drain valve 41 closed is less than the specified amount, that is, when the determination result in step S11 is "NO", the control unit 100 returns to step S1 (I), opens the drain valve 41 (step S1), and resumes dehydration (step S2).

[0034] On the other hand, if ΔH detected in step S11 is equal to or greater than a specified amount, it is highly likely that water is continuously draining from the laundry, and by allowing a further predetermined additional time to elapse, the center of gravity of the contents in the washing tub is likely to change. Therefore, when the change amount ΔH of the water level detected within the above-mentioned predetermined time is equal to or greater than the specified amount, that is, when the determination result in step S11 is "YES", the control unit 100 returns to step S10 and allows a further additional time to elapse with the drain valve 41 closed. The control unit 100 calculates the change amount ΔH of the water level detected within the above-mentioned additional time based on the detection value input from the water level sensor 60 (step S11). If the determination result in step S11 becomes "YES" again, the processes of steps S10 and S11 may be repeated a plurality of times until the determination result in step S11 becomes "NO". In the processes of steps S10 and S11 from the second time onwards, the "predetermined time" can be read as the "additional time" and applied. The start time of the above-mentioned predetermined time refers to the point in time when the drain valve 41 is closed. Also, the length of the time set for the first predetermined time and the additional times from the second time onwards may be the same or different, and the specified amounts set may be the same or different.

[0035] (Embodiment 2) In Embodiment 2, the features specific to Embodiment 2 will be mainly described, and the description of the content overlapping with Embodiment 1 above will be omitted. The washing machine 1 of Embodiment 2 is substantially the same as the washing machine 1 of Embodiment 1 except that the detection of unbalance is performed multiple times.

[0036] FIG. 5 is a flowchart showing a preferred example of the processing by the control unit 100 in Embodiment 2. Even if an imbalance is detected once in step S3, there is a possibility of slight unevenness of the laundry, detection errors, etc., and there is a possibility that the imbalance can be eliminated without performing the imbalance correction rinsing described later. Therefore, when the determination result becomes "NO" in step S11 and returns to step S1 after going through steps S8 to S11 (I), the control unit 100, when the unevenness detection unit 50 detects unevenness of the contents in the washing tub 13 in the second and subsequent step S3 (x), may further cause the unevenness detection unit 50 to detect the unevenness of the contents (step S12). When the number of times (N1) that the unevenness detection unit 50 detects the unevenness of the contents in the washing tub 13 in step S12 is less than a predetermined number, the control unit 100 stops dehydration (step S8) and performs a process of closing the drain valve 41 (step S8). N1 is an integer of 1 or more. The processing after step S6 is the same as that in Embodiment 1, so the description is omitted. Further, when no imbalance is detected in step S3, that is, when the determination result is "NO", the process proceeds to step S4, but the processing in steps S4 to S7 is the same as that in Embodiment 1, so the description is omitted.

[0037] In step S12, the control unit 100 may cause the unevenness detection unit 50 to detect the unevenness of the contents again after a predetermined time has elapsed with the stirring member 21 and the washing tub 13 stopped. Further, the control unit 100 may cause the unevenness detection unit 50 to detect the unevenness of the contents again while performing processes such as rotating the stirring member 21 and rotating the washing tub 13, or after performing these processes.

[0038] The above N1 may be set in advance, or may be set according to the capacity of the laundry put into the washing tub 13. Specifically, it is preferable to set N1 to be larger as the capacity of the laundry is larger. The capacity of the laundry is preferably the capacity before water is supplied to the washing tub, that is, before the laundry contains water. The control unit 100 puts the laundry into the washing tub 13 Before water is supplied into the washing tub 13 (before the washing process), a capacity determination process for measuring the capacity of the laundry put into the washing tub may be performed.

[0039] When the capacity of the laundry is large, the vibration immediately after the start of dehydration tends to be large, and it becomes easier to detect imbalance in step S3. However, if the initial stage of dehydration can be overcome, dehydration may be completed safely. Therefore, when the capacity determination unit 70 determines that the capacity of the laundry is large, it is preferable to set the above N1 to a large value. For example, it is preferably 3 times or more and 5 times or less. On the other hand, when the capacity determination unit 70 determines that the capacity of the laundry is small and imbalance is detected in step S3, since it is less likely that the imbalance state will be resolved even if water drainage from the laundry is promoted, it is preferable to set N1 to be less than when the capacity of the laundry is large.

[0040] If the number of times of detecting the unevenness of the contents in step S12 is equal to or more than a predetermined number of times, it can be determined that the degree of unevenness of the contents is large, and there is little possibility of resolving the imbalance even if water drainage of the laundry is promoted in steps S8 to S11. Therefore, when the number of times the unevenness detection unit 50 detects the unevenness of the contents is equal to or more than a predetermined number of times, that is, when the determination result in step S12 is "YES", the control unit 100 closes the drain valve 41, opens the water supply valve 31 to supply water to the washing tub 13, and performs an imbalance correction rinsing process (step S12). In the imbalance correction rinsing process, the control unit 100 closes the drain valve 41, opens the water supply valve 31 to supply water to the washing tub 13, and rotates the washing tub 13 and the stirring member 21 with water stored in the washing tub 13 to loosen the unevenly distributed laundry, and then performs dehydration, whereby a series of washing processes are completed (END).

[0041] As described above, embodiments of the present disclosure have been explained. However, the present disclosure is not limited to the above embodiments and can be implemented in various forms without departing from the gist thereof. Also, a plurality of components disclosed in the above embodiments can be modified as appropriate. For example, a certain component among all the components shown in a certain embodiment may be added to the components of another embodiment, or some of the components among all the components shown in a certain embodiment may be deleted from the embodiment.

[0042] In addition, for the purpose of facilitating understanding of the invention, the drawings schematically show each component mainly. The thickness, length, number, interval, etc. of each illustrated component may be different from the actual ones for convenience in drawing preparation. Also, it goes without saying that the configuration of each component shown in the above embodiments is an example and is not particularly limited, and various changes can be made without substantially departing from the effects of the present disclosure.

Description of Reference Numerals

[0043] 1: Washing machine 10: Housing 11: Lid 12: Operation display unit 13: Washing tub (inner tub) 14: Outer tub 20: Driving unit 21: Stirring member 30: Water supply unit 31: Water supply valve 32: Water supply path 40: Drainage unit 41: Drain valve 42: Inner tub drainage path 43: Outer tub drainage path 44: External drainage path 50: Offset detection unit 60: Sensor (water level sensor) 61: Tube 70: Capacity determination unit 100: Control unit

Claims

1. A washing tub for containing the contents, A water supply valve for supplying water to the washing tub, A drain valve for draining water from the washing tub, An imbalance detection unit for detecting the imbalance of the contents in the washing tub, A control unit for controlling the opening and closing of the drain valve based on the detection result by the imbalance detection unit, A water level sensor for detecting the water level in the washing tub, and comprising, When the imbalance detection unit detects the imbalance of the contents, the control unit stops dehydration, closes the drain valve, and if the change amount of the water level detected within a predetermined time in the state where the drain valve is closed is less than a specified amount, opens the drain valve and resumes dehydration. A washing machine.

2. If the change amount of the water level per the predetermined time is equal to or more than the specified amount, and further if the change amount of the water level detected within an additional time in the state where the drain valve is closed is less than the specified amount, the control unit according to claim 1, opens the drain valve and resumes dehydration. The washing machine described.

3. If the number of times the imbalance detection unit detects the imbalance of the contents is less than a specified number of times, the control unit according to claim 1 or 2 stops dehydration and performs a process of closing the drain valve. The washing machine described.

4. If the number of times the imbalance detection unit detects the imbalance of the contents is equal to or more than a specified number of times, the control unit closes the drain valve, opens the water supply valve, supplies water to the washing tub, and performs an imbalance correction rinsing step. The washing machine described in claim 1 or 2.

5. The specified number of times for detecting the imbalance of the contents is set according to the capacity of the laundry put into the washing tub. The washing machine described in claim 1 or 2.

6. Having an outer tub disposed outside the washing tub, The washing tub is not provided with holes through which water enters and exits between the washing tub and the outer tub on the side wall of the washing tub. The washing machine described in claim 1 or 2.

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