washing machine

Abstract

To provide a washing machine in which the occurrence of water biting in a washing tub in a dewatering step can be reduced.SOLUTION: A fully automatic washing machine 1 comprises: a drive motor 31 driving a washing and dehydrating tub; a control unit 101 controlling the drive motor 31; and a water level detector 60 which includes a pair of electrodes arranged in a space between a bottom surface portion of an outer tub and a bottom surface portion of the washing and dehydrating tub, and which detects an electric current flowing between the pair of electrodes changing according to the water level in the outer tub and outputs a detection signal showing the magnitude of the electric current. The control unit 101 detects the water level in the outer tub based on the detection signal from the water level detector 60 in the middle of increasing the rotation of the washing and dehydrating tub to the dewatering rotational frequency, and when based on the detected water level, determines that a drain failure state has occurred in which drainage from the outer tub is difficult to be performed smoothly, controls the drive motor 31 in such a manner that the increase of the rotation of the washing and dehydrating tub to the dewatering rotational frequency becomes slower than the case where the drain failure state has not occurred.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a washing machine. [Background technology]

[0002] Conventionally, in a washing machine, a spin-drying process is performed after the washing and rinsing processes. In the spin-drying process, the washing tub in which the laundry is stored, i.e., the washing and spin-drying tub or drum, rotates at high speed, and water is squeezed out of the laundry by centrifugal force generated in the washing tub. The water drained from the laundry is discharged into an outer tub surrounding the washing tub, and is discharged outside the machine through a drainage path consisting of a drain hose or the like (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-103419 A Summary of the Invention [Problem to be solved by the invention]

[0004] If foreign matter such as lint accumulates in the drain hose or if the drain hose is not properly installed outside the machine, the drainage from the outer tub may deteriorate. If the spin cycle is performed in such a state, the water discharged from the laundry will not be smoothly discharged from the outer tub, and there is a risk that the rotating washing tub and the water accumulated at the bottom of the outer tub will come into contact with each other while the rotation speed of the washing tub is being increased to a predetermined spin rotation speed, which may cause a so-called water bite, and there is a risk of abnormal noise due to water bite.

[0005] In addition, if the outer tub vibrates violently when the washing tub rotation speed is increased during the spin-drying process, the water drained from the laundry will sway inside the outer tub and will not be discharged smoothly, which may cause water to get stuck in the washing tub.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a washing machine capable of reducing the occurrence of water biting in the washing tub during the spin-drying process. [Means for solving the problem]

[0007] A washing machine according to a first aspect of the present invention includes an outer tub elastically supported in a housing, a drainage unit for draining water from the outer tub, a washing tub rotatably arranged in the outer tub and accommodating laundry, a drive motor for driving the washing tub, a control unit for controlling the drive motor to execute a spin-drying process for rotating the washing tub at a predetermined spin-drying speed, and a detection unit including a pair of electrodes arranged in a space between a bottom of the outer tub and a bottom of the washing tub, detecting a current flowing between the pair of electrodes that changes depending on a water level in the outer tub, and outputting a detection signal indicating the magnitude of the detected current. Here, the control unit detects, during the process of increasing the rotation speed of the washing tub to the spin-drying speed, rotating the washing tub at a first detection rotation speed lower than the spin-drying rotation speed, acquiring the detection signal from the detection unit during the rotation, and detecting the water level; When it is determined based on the detected water level that a poor drainage state occurs in which drainage from the outer tank is not performed smoothly, ,before Control the drive motor By rotating the washing tub at the first detection rotation speed for a longer time than when the poor drainage state does not occur, the start-up of the rotation of the washing tub to the dehydration rotation speed is delayed.

[0008] In addition, the "poor drainage state in which drainage from the outer tub is not performed smoothly" includes not only a state in which drainage from the outer tub is not performed smoothly at the time of judgment, but also a state in which drainage from the outer tub is not performed smoothly when the rotation speed of the washing tub increases after the judgment.

[0009] According to the above configuration, when a drainage problem occurs, the drainage of water from the laundry is suppressed, so that the water is prevented from accumulating in the outer tub until it touches the bottom of the washing tub, and the occurrence of water sticking in the washing tub can be reduced. Furthermore, the occurrence of abnormal noise due to water sticking can also be reduced. Furthermore, according to the above configuration, the time for which the washing tub is rotated at the first detection rotation speed is lengthened, so that when the water level in the outer tub is low, the rotation speed of the washing tub can be increased from the first detection rotation speed. Even if more water is discharged from the laundry due to the subsequent increase in rotation speed than at the first detection rotation speed, water is prevented from accumulating in the outer tub until it touches the bottom of the washing tub, thereby reducing the occurrence of water biting in the washing tub.

[0010] In the washing machine according to this aspect, the control unit determines whether or not the poor drainage state has occurred based on the detected water level.

[0011] If the drainage performance of the drain section deteriorates and water does not drain smoothly from the outer tank, the water level in the outer tank will increase.

[0012] According to the above configuration, the control unit determines whether or not a poor drainage condition has occurred based on the water level detected by the detection unit, so that it is possible to detect the occurrence of a poor drainage condition caused by a deterioration in the drainage performance of the drainage unit.

[0013] Also, in the washing machine according to this aspect, the control unit determines whether or not the poor drainage state has occurred based on the magnitude of the detected fluctuation in the water level.

[0014] If the outer tub vibrates significantly, causing the water in the outer tub to sway and preventing smooth drainage, the large vibrations of the outer tub will cause large fluctuations in the water level in the outer tub.

[0015] According to the above configuration, the control unit determines whether or not a poor drainage condition has occurred based on the magnitude of the water level fluctuation detected by the detection unit, so that it is possible to detect the occurrence of a poor drainage condition caused by large vibrations in the outer tank.

[0016] A washing machine according to a second aspect of the present invention comprises an outer tub elastically supported within a housing, a drainage unit for draining water from the outer tub, a washing tub rotatably arranged within the outer tub and containing laundry, a drive motor for driving the washing tub, a control unit for controlling the drive motor to execute a spin-drying process for rotating the washing tub at a predetermined spin-drying speed, and a detection unit including a pair of electrodes arranged in the space between a bottom portion of the outer tub and a bottom portion of the washing tub, detecting a current flowing between the pair of electrodes which changes depending on the water level in the outer tub, and outputting a detection signal indicating the magnitude of the detected current. The control unit is While the rotation of the washing tub is increased to the dehydration rotation speed, rotating the washing tub at a first detection rotation speed lower than the spin-drying rotation speed, acquiring the detection signal from the detection unit during the rotation, and detecting the water level; Based on the detected water level, The above Drainage from the outer tank is not smooth. Poor drainage condition It was determined that In case, Controlling the drive motor The time for which the washing tub is rotated at the first detection rotation speed is made longer than when the poor drainage state does not occur, or the acceleration when the rotation speed of the washing tub is increased from the first detection rotation speed is made smaller, thereby slowing down the start-up of the rotation of the washing tub to the dehydration rotation speed. The outer tub has a bottom surface formed with a recess recessed from an inner surface of the bottom surface, and the pair of electrodes protrude upward from the bottom surface of the recess. The control unit rotates the washing tub at a second detection rotation speed lower than the spin-drying rotation speed and higher than the first detection rotation speed, detects the water level with the detection unit during the rotation, and reduces the value of the spin-drying rotation speed when the detected water level is lower than a threshold value.

[0017] According to the above configuration, when the time for rotating the washing tub at the first detection rotation speed is extended, the rotation speed of the washing tub can be increased from the first detection rotation speed when the water level in the outer tub is low. Therefore, even if more water is discharged from the laundry due to the subsequent increase in rotation speed than at the first detection rotation speed, water is prevented from accumulating in the outer tub until it touches the bottom of the washing tub, thereby reducing the occurrence of water biting in the washing tub.

[0018] In addition, if the acceleration rate is reduced when increasing the rotation speed of the washing tub from the first detection rotation speed, less water is discharged from the laundry when the rotation speed increases from the first detection rotation speed, thereby preventing water from accumulating in the outer tub until it touches the bottom of the washing tub, thereby reducing the occurrence of water biting in the washing tub.

[0020] According to the above configuration, some of the water discharged from the laundry into the outer tub accumulates in the recess while the rotation of the washing tub rises from the first detection rotation speed. If the outer tub vibrates significantly while the rotation of the washing tub rises from the first detection rotation speed and reaches the second detection rotation speed, the water accumulated in the recess is scattered and removed from the recess, and water remaining in the recess when the second detection rotation speed is reached can be prevented.

[0021] The detector is configured such that a pair of electrodes protrude upward from the bottom surface of the recess, so that it can detect the water level in the recess. If the water leaks out of the recess due to large vibrations of the outer tub and the water level detected by the detector at the second detection rotation speed falls below the threshold, the value of the spin-dry rotation speed is lowered. This reduces the vibration of the outer tub when the washing tub rotates at the spin-dry rotation speed.

[0022] A washing machine according to a third aspect of the present invention comprises an outer tub elastically supported within a housing, a drainage unit for draining water from the outer tub, a washing tub rotatably arranged within the outer tub and storing laundry, a drive motor for driving the washing tub, a control unit for controlling the drive motor to execute a spin-drying process for rotating the washing tub at a predetermined spin-drying speed, and a detection unit including a pair of electrodes arranged in a space between a bottom portion of the outer tub and a bottom portion of the washing tub, detecting a current flowing between the pair of electrodes which changes depending on the water level in the outer tub, and outputting a detection signal indicating the magnitude of the detected current. The control unit rotates the washing tub at a first detection rotation speed lower than the spin rotation speed while ramping up the rotation of the washing tub to the spin rotation speed, acquires the detection signal from the detection unit within a predetermined acquisition period to detect fluctuations in the water level within the acquisition period, and when it determines based on the magnitude of the detected water level fluctuations that a poor drainage condition in which water is not being drained smoothly from the outer tub has occurred, it controls the drive motor so that the ramp-up of the rotation of the washing tub to the spin rotation speed is slower than if the poor drainage condition does not occur. If the outer tub vibrates significantly, causing the water in the outer tub to sway and preventing smooth drainage, the large vibrations of the outer tub will cause large fluctuations in the water level in the outer tub. According to the above configuration, the control unit determines whether or not a poor drainage condition has occurred based on the magnitude of the water level fluctuation detected by the detection unit while the washing tub is rotating at the first detection rotation speed, so that it is possible to detect the occurrence of a poor drainage condition caused by large vibrations of the outer tub. The present invention FourthThe washing machine according to the embodiment includes an outer tub elastically supported in a housing, a drainage unit for draining water from the outer tub, a washing tub rotatably arranged in the outer tub and accommodating laundry, a drive motor for driving the washing tub, a control unit for controlling the drive motor to execute a spin-drying process for rotating the washing tub at a predetermined spin-drying speed, and a detection unit including a light-emitting element and a light-receiving element located at a predetermined height from the bottom of the outer tub in a space between the bottom of the outer tub and the bottom of the washing tub, detecting the light transmittance between the light-emitting element and the light-receiving element, and outputting a detection signal according to the detected transmittance. Here, the control unit detects, during the process of raising the washing tub to the spin-drying speed, The washing tub is rotated at a first detection rotation speed which is lower than the spin-drying rotation speed, and the detection signal is obtained from the detection unit during the rotation. and detecting whether water is present at the predetermined height by detecting the presence of water at the predetermined height. Controlling the drive motor than when there is no water at said predetermined height By lengthening the time for rotating the washing tub at the first detection rotation speed, The washing tub rotation speed is slowed down. to.

[0023] According to the above configuration, when the water is not being smoothly discharged from the outer tub, the water discharge from the laundry is suppressed, so that the water is prevented from accumulating in the outer tub until it touches the bottom of the washing tub, and the occurrence of water pinching in the washing tub can be reduced. Furthermore, the occurrence of abnormal noise due to water pinching can also be reduced. Furthermore, according to the above configuration, the time for which the washing tub is rotated at the first detection rotation speed is lengthened, so that when the water level in the outer tub is low, the rotation speed of the washing tub can be increased from the first detection rotation speed. Even if more water is discharged from the laundry due to the subsequent increase in rotation speed than at the first detection rotation speed, water is prevented from accumulating in the outer tub until it touches the bottom of the washing tub, thereby reducing the occurrence of water biting in the washing tub. Effect of the Invention

[0024] According to the present invention, a washing machine capable of reducing the occurrence of water biting in the washing tub during the spin-drying process can be provided.

[0025] The effects and significance of the present invention will become clearer from the following description of the embodiments. However, the following embodiment is merely an example of how the present invention can be put into practice, and the present invention is not limited to the embodiment described below. [Brief description of the drawings]

[0026] [Figure 1]FIG. 1 is a side cross-sectional view of a fully automatic washing machine according to a first embodiment. [Diagram 2] Fig. 2(a) is a plan cross-sectional view of the outer tub according to embodiment 1. Fig. 2(b) is a side cross-sectional view of the periphery of the water level detector in the outer tub according to embodiment 1, taken along line AA' in Fig. 2(a). [Diagram 3] FIG. 3 is a block diagram showing a configuration of the fully automatic washing machine according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing a control process by the control unit in the spin-drying step according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing a water entrapment prevention control process according to the first embodiment. [Figure 6] Fig. 6(a) is a flowchart showing a water level abnormality determination process included in the water bite prevention control process according to embodiment 1. Fig. 6(b) is a flowchart showing a reference value acquisition process for acquiring a reference value of a detection signal used in the water level abnormality determination process according to embodiment 1. [Figure 7] FIG. 7 is a flowchart showing a vibration abnormality determination process included in the water bite prevention control process according to the first embodiment. [Figure 8] FIG. 8 is a flowchart showing a water entrapment prevention control process according to the first modified example. [Figure 9] Fig. 9(a) is a flowchart showing a water level detection process included in the water bite prevention control process according to Modification Example 1. Fig. 9(b) is a flowchart showing a water level abnormality determination process included in the water bite prevention control process according to Modification Example 1. [Figure 10] FIG. 10 is a flowchart showing a water entrapment prevention control process according to the second modified example. [Figure 11] FIG. 11 is a flowchart showing a control process by the control unit in the spin-drying step according to the third modified example. [Figure 12] FIG. 12 is a flowchart showing a vibration prevention control process according to the third modification. [Figure 13] FIG. 13 is a side cross-sectional view of the periphery of the water level detector in the outer tank according to the second embodiment. [Figure 14] FIG. 14 is a flowchart showing a water entrapment prevention control process according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, a fully automatic washing machine 1, which is one embodiment of a washing machine of the present invention, will be described with reference to the drawings.

[0028] <Embodiment 1> FIG. 1 is a side cross-sectional view of a fully automatic washing machine 1 according to the first embodiment.

[0029] The fully automatic washing machine 1 has a housing 10 which constitutes its exterior. The housing 10 includes a rectangular cylindrical body 11 with upper and lower open faces, a top plate 12 which covers the top face of the body 11, and a foot stand 13 which supports the body 11. A laundry insertion opening 14 is formed in the top plate 12. The laundry insertion opening 14 is covered by an upper lid 15 which can be opened and closed.

[0030] An outer tub 20 having an open top is elastically suspended and supported by four suspension rods 21 having vibration isolation devices within the housing 10. The outer tub 20 has a substantially cylindrical peripheral surface portion 201 and a substantially disk-shaped bottom surface portion 202.

[0031] A washing / dehydrating tub 22 with an open top is disposed within the outer tub 20. The washing / dehydrating tub 22 has a substantially cylindrical peripheral surface portion 22a and a substantially disk-shaped bottom surface portion 22b, and rotates about a rotation axis extending in the vertical direction. A large number of dehydration holes 22c are formed on the peripheral surface portion 22a of the washing / dehydrating tub 22 all around. The washing / dehydrating tub 22 corresponds to the washing tub of the present invention.

[0032] A balance ring 23 is provided on the upper part of the washing / drying tub 22. A pulsator 24 is rotatably disposed on the bottom part of the washing / drying tub 22. A plurality of blades 24a are provided radially on the surface of the pulsator 24.

[0033] A drive unit 30 that generates torque to drive the washing / spinning tub 22 and the pulsator 24 is disposed on the outside of the bottom surface 202 of the outer tub 20. The drive unit 30 includes a drive motor 31 and a transmission mechanism 32. The transmission mechanism 32 has a clutch mechanism 32a, and by switching operation of the clutch mechanism 32a, the torque of the drive motor 31 is transmitted only to the pulsator 24 to rotate only the pulsator 24 in the washing step and the rinsing step, and the torque of the drive motor 31 is transmitted to the pulsator 24 and the washing / spinning tub 22 to rotate the pulsator 24 and the washing / spinning tub 22 integrally in the spinning step.

[0034] A drain outlet 203 is formed in the bottom surface 202 of the outer tub 20. A drain unit 40 is connected to the drain outlet 203. The drain unit 40 includes a drain valve 41 and a drain hose 42 connected to the drain valve 41. When the drain valve 41 is opened, the water stored in the washing and spin-drying tub 22 and the outer tub 20 is drained outside the machine through the drain hose 42.

[0035] A water supply unit 50 for supplying tap water into the washing and spin-drying tub 22, i.e., the outer tub 20, is disposed at the rear of the top panel 12. The water supply unit 50 has a water supply valve 51. A water inlet 51a of the water supply valve 51 is connected to a water faucet via a water supply hose. When the water supply valve 51 is opened, tap water from the water faucet flows through a water supply passage 52 and is supplied into the washing and spin-drying tub 22 from a water inlet 53.

[0036] Fig. 2(a) is a plan cross-sectional view of the outer tub 20 according to embodiment 1. Fig. 2(b) is a side cross-sectional view of the outer tub 20 around the water level detector 60 according to embodiment 1, taken along line AA' in Fig. 2(a).

[0037] A step 204 extending from the center toward the outer periphery is provided on the bottom portion 202 of the outer tub 20, and the inner surface of the bottom portion 202 slopes downward from the right side of the step 204 in the direction of the dashed arrow in Fig. 2. On the left side of the step 204, where the inner surface of the bottom portion 202 is lowest, a drain recess 205 is formed by recessing the bottom portion 202, and a drain port 203 is provided within the drain recess 205. The inner surface of the bottom portion 202 of the outer tub 20 slopes downward from the center toward the outer periphery.

[0038] A cylindrical mounting hole 206 that protrudes slightly downward is formed in the bottom surface portion 202 of the outer tub 20 near the outer periphery and to the left of the drain recess 205, i.e., near the higher side of the inner surface of the bottom surface portion 202. An electrode-type conductivity sensor is attached from below to the mounting hole 206 as a water level detector 60. The water level detector 60 corresponds to the detection unit of the present invention.

[0039] The water level detector 60 has an upper part 60a having a cylindrical shape with an outer diameter smaller than that of the lower part 60b, and the upper part 60a is fitted into the mounting port 206. A packing 210 is provided between the lower part 60b and the mounting port 206 to seal the water. The tip of the upper part 60a protrudes above the inner surface of the bottom part 202 and has a groove part 61 in the center. The bottom surface of the groove part 61 is lower than the inner surface of the bottom part 202 around the mounting port 206, and the part of the groove part 61 lower than the inner surface of the bottom part 202 becomes a residual water pocket 207 recessed from the inner surface of the bottom part 202. In this embodiment 1, the residual water pocket 207 is a rectangular recess. The residual water pocket 207 may be a recess of any shape, such as a circle. The residual water pocket 207 corresponds to the recess of the present invention.

[0040] In the water level detector 60, a pair of electrodes 62 are provided on two opposing side wall surfaces of the groove portion 61. The pair of electrodes 62 have a rectangular plate shape and are disposed in the space between the bottom portion 202 and the bottom portion 22b of the washing and spin-drying tub 22 so as to protrude upward from the bottom surface of the residual water pocket 207 in the bottom portion 202.

[0041] The water level detector 60 is used to detect the water level in the outer tub 20 in the control process in the spin-drying step, which will be described later. When the water discharged from the laundry is discharged from the outer tub 20 in the spin-drying step, some of the water passes through the water level detector 60 and accumulates in the remaining water pocket 207. If water is not completely drained from the outer tub 20 and overflows from the drain recess 205, water may accumulate around the water level detector 60, higher than the upper surface of the remaining water pocket 207. When water accumulates at least in the remaining water pocket 207, water is present between the pair of electrodes 62.

[0042] When detecting the water level in the outer tub 20, the water level detector 60 applies a voltage to the pair of electrodes 62. When water is present between the pair of electrodes 62, a current corresponding to the conductivity of the water flows between the electrodes. As the water level in the outer tub 20 rises and the water level between the pair of electrodes 62 becomes higher, the surface area of ​​the electrode 62 in contact with the water increases, and therefore the current becomes larger.

[0043] The water level detector 60 detects the water level between the pair of electrodes 62, i.e., the current flowing between the pair of electrodes 62 which changes depending on the water level in the outer tub 20, and outputs a detection signal indicating the magnitude of the detected current to the control unit 101. In the first embodiment, the detection signal is a voltage signal, and in this case, the higher the water level in the outer tub 20, the larger the voltage value. The water level detector 60 can detect the water level in the outer tub 20 from the bottom surface of the residual water pocket 207, where the lower ends of the pair of electrodes 62 are located, to the position of the upper ends of the pair of electrodes 62.

[0044] FIG. 3 is a block diagram showing a configuration of the fully automatic washing machine 1 according to the first embodiment.

[0045] In addition to the above-mentioned configuration, the fully automatic washing machine 1 includes a control unit 100. The control unit 100 includes a control unit 101, a memory unit 102, a motor drive unit 103, a clutch drive unit 104, a water supply drive unit 105, and a drain drive unit 106. The fully automatic washing machine 1 also includes an operation unit 110 and a water level sensor 120.

[0046] The operation unit 110 includes various operation buttons such as a power button for turning on and off the power to the fully-automatic washing machine 1, a start / pause button for starting and pausing a washing operation, a course selection button for selecting an arbitrary operation course from a plurality of operation courses related to the washing operation, etc. The operation unit 110 outputs an input signal to the control unit 101 according to the operation button operated by the user.

[0047] Water level sensor 120 is a diaphragm type water level sensor, and is connected via a hose to an air trap provided at the bottom of outer tub 20. Water level sensor 120 detects the air pressure in the air trap to detect the water level in washing and spin-drying tub 22, i.e., in outer tub 20, and outputs a water level signal to control unit 101 according to the detected water level.

[0048] The motor driving unit 103 drives the driving motor 31 in accordance with a control signal output from the control unit 101. The motor driving unit 103 includes a rotation sensor that detects the rotation speed of the driving motor 31, an inverter circuit, etc., and adjusts the driving power so that the driving motor 31 rotates at the rotation speed set by the control unit 101.

[0049] The clutch driving unit 104 drives the clutch mechanism 32a of the transmission mechanism unit 32 in accordance with a control signal output from the control unit 101. The water supply driving unit 105 drives the water supply valve 51 in accordance with a control signal from the control unit 101. The drain driving unit 106 drives the drain valve 41 in accordance with a control signal from the control unit 101.

[0050] The storage unit 102 includes an EEPROM, a RAM, etc. The storage unit 102 stores programs for executing various operation courses of the washing operation. The storage unit 102 also stores various operation conditions used for the washing operation.

[0051] The control unit 101 includes a CPU and the like, and controls the motor drive unit 103, the clutch drive unit 104, the water supply drive unit 105, the drain drive unit 106, and the like in accordance with a program stored in the storage unit 102.

[0052] In the fully automatic washing machine 1, various washing courses are performed under the control of the control unit 101. In the washing course, the washing step, the intermediate spin-drying step, the rinsing step, and the final spin-drying step are performed in order. Depending on the washing course, the rinsing step may be performed twice, in which case the intermediate spin-drying step is performed after the first rinsing step.

[0053] Before the washing step, the load amount of laundry is detected. In the load amount detection, for example, after the laundry is put in, pulsator 24 rotates with no water in washing and spinning tub 22, and the load amount is determined based on the drive current of drive motor 31 and the amount of inertial rotation until drive motor 31 stops. The water level and time in the washing step and rinsing step are determined according to the detected load amount.

[0054] In the washing and rinsing steps, the pulsator 24 rotates rightward and leftward while water is stored in the washing and spin-drying tub 22. The rotation of the pulsator 24 generates a water flow in the washing and spin-drying tub 22. In the washing step, detergent is added to the washing and spin-drying tub 22, and the laundry is washed by the generated water flow and detergent. In the rinsing step, the laundry is rinsed by the generated water flow.

[0055] In the intermediate spin-drying step and the final spin-drying step, the washing / spin-drying tub 22 and the pulsator 24 rotate together at a high speed at a predetermined spin-drying speed. The laundry is spin-dried by the action of the centrifugal force generated in the washing / spin-drying tub 22. In the spin-drying step, the drain valve 41 is in an open state. The water squeezed out from the laundry is discharged into the outer tub 20 through the spin-drying hole 22c, and is discharged outside the machine through the drain outlet 203 and the drain hose 42.

[0056] The intermediate dehydration process and the final dehydration process are both dehydration processes, and hereinafter, when there is no need to distinguish between them, they will simply be referred to as dehydration processes.

[0057] However, if foreign matter such as lint accumulates in the drain hose 42 or if the drain hose 42 is not properly installed outside the machine, the drainage from the outer tub 20 may deteriorate. If the spin-drying process is performed in such a state, the water discharged from the laundry will not be smoothly discharged from the outer tub 20, and there is a risk that the rotating washing / spin-drying tub 22 will come into contact with the water accumulated at the bottom of the outer tub 20 while the rotation speed of the washing / spin-drying tub 22 is being increased to the spin-drying rotation speed, which may cause so-called water bite, and there is a risk of abnormal noise being generated due to water bite.

[0058] In addition, if the outer tub 20 vibrates significantly when the rotation speed of the washing and dehydrating tub 22 is increased during the dehydration process, the water drained from the laundry will sway inside the outer tub 20 and will not be drained smoothly, which may result in water getting stuck in the washing and dehydrating tub 22.

[0059] Therefore, in the first embodiment, when the rotation speed of the washing and dewatering tub 22 is increased in the dewatering process, a water bite prevention control process is executed to prevent the occurrence of water bite in the washing and dewatering tub 22.

[0060] Fig. 4 is a flowchart showing control processing by the control unit 101 in the spin-drying step according to the first embodiment. Fig. 5 is a flowchart showing water bite prevention control processing according to the first embodiment. Fig. 6(a) is a flowchart showing water level abnormality determination processing included in the water bite prevention control processing according to the first embodiment. Fig. 6(b) is a flowchart showing reference value acquisition processing for acquiring a reference value of a detection signal used in the water level abnormality determination processing according to the first embodiment. Fig. 7 is a flowchart showing vibration abnormality determination processing included in the water bite prevention control processing according to the first embodiment.

[0061] 4, when the spin-drying process is started, control unit 101 sets the target rotation speed of washing / drying tub 22 to a first rotation speed and starts drive motor 31 (S101). The first rotation speed is set to a rotation speed slightly higher than the rotation speed at the so-called horizontal resonance point (e.g., 50 to 60 rpm) at which washing / drying tub 22 and outer tub 20 greatly vibrate in the horizontal direction due to resonance, and is set to, for example, 120 rpm.

[0062] When the rotation speed of washing / drying tub 22 reaches the first rotation speed (S102: YES), control unit 101 maintains the rotation speed of washing / drying tub 22 at the first rotation speed (S103) and waits for a first maintenance time to elapse from the start of the maintenance (S104). The first maintenance time is a period of several tens of seconds, for example 30 seconds, and is set before the spin-drying process depending on the load of laundry in washing / drying tub 22, etc. While the first maintenance time elapses, most of the amount of water that can be discharged can be squeezed out of the laundry by centrifugal force acting at the first rotation speed.

[0063] When the first maintenance time has elapsed (S104: YES), the control unit 101 sets the target rotation speed to the second rotation speed and increases the rotation speed of the washing and spin-drying tub 22 (S105). The second rotation speed is set to a rotation speed slightly higher than the rotation speed at the so-called vertical resonance point (e.g., 200 to 220 rpm) at which the washing and spin-drying tub 22 and the outer tub 20 greatly vibrate in the vertical direction due to resonance, and is set to, for example, 240 rpm.

[0064] When the rotation speed of washing / drying tub 22 reaches the second rotation speed (S106: YES), control unit 101 maintains the rotation speed of washing / drying tub 22 at the second rotation speed (S107) and waits for the second maintenance time to elapse from the start of the maintenance (S104). The second maintenance time is a time of several tens of seconds to about one minute, for example 50 seconds, which is longer than the first maintenance time, and is set before the spin-drying process depending on the load of laundry in washing / drying tub 22, etc. Also, the second maintenance time can be extended by the water-biting prevention control shown in FIG. 5. During the second maintenance time, most of the amount of water that can be discharged can be discharged from the laundry by the centrifugal force acting at the second rotation speed.

[0065] When the second maintenance time has elapsed (S108: YES), the control unit 101 sets the target rotation speed to the spin-drying rotation speed and increases the rotation speed of the washing and spin-drying tub 22 (S109). The spin-drying rotation speed is set to, for example, 800 rpm. The spin-drying rotation speed in the final spin-drying step may be set higher than the spin-drying rotation speed in the intermediate spin-drying steps.

[0066] As the second maintenance time approaches the end, the amount of water drained from the laundry decreases, but as the rotation speed of the washing and spin-drying tub 22 increases from the second rotation speed, the centrifugal force acting on the laundry increases, and more water may be drained from the laundry than at the second rotation speed.

[0067] When the rotation speed of the washing / drying tub 22 reaches the spin-drying rotation speed (S110: YES), the control unit 101 maintains the rotation speed of the washing / drying tub 22 at the spin-drying rotation speed (S111) and waits for the spin-drying time to elapse from the start of the maintenance (S112). The spin-drying time is about several minutes to tens of minutes, and is set before the spin-drying process depending on the load of laundry in the washing / drying tub 22, etc.

[0068] When the spin-drying time has elapsed (S112: YES), the control unit 101 stops the drive motor 31 and stops the washing and spin-drying tub 22 (S113). Thus, the spin-drying process ends.

[0069] The first rotation speed and the second rotation speed are rotation speeds in the low-speed region, and the dehydration rotation speed is a rotation speed in the high-speed region.

[0070] In parallel with the control process for the spin-drying step in FIG. 4, the control unit 101 executes a control process for preventing water entrapment in FIG.

[0071] 5, control unit 101 monitors whether the rotation speed of washing / drying tub 22 has reached a second rotation speed (S201). The second rotation speed corresponds to a first detection rotation speed of the present invention.

[0072] When the rotation speed of washing / spinning tub 22 reaches the second rotation speed (S201: YES), control unit 101 operates water level detector 60, i.e., applies a voltage to pair of electrodes 62, and starts acquiring the detection signal output from water level detector 60, i.e., the voltage value (S202). The detection signal is acquired at a predetermined sampling rate, for example, at intervals of 0.1 seconds.

[0073] When a predetermined acquisition time, for example, 15 seconds, has elapsed since the start of acquisition of the detection signal (S203: YES), the control unit 101 stops the operation of the water level detector 60 and ends acquisition of the detection signal (S204). In this manner, a plurality of detection signals are acquired.

[0074] Next, the control unit 101 executes the water level abnormality determination process of FIG. 6(a) (S205), and also executes the vibration abnormality determination process of FIG. 7 (S206).

[0075] 6(a), the control unit 101 calculates the average value of the values ​​of the acquired detection signals, i.e., the voltage values ​​(S301). Next, the control unit 101 reads out the reference value of the detection signal from the storage unit 102 (S302). The reference value is acquired by the reference value acquisition process of FIG. 6(b).

[0076] The reference value acquisition process is executed at the end of the washing and rinsing steps, for example, between when the pulsator 24 stops operating and when draining starts. At this time, the pair of electrodes 62 of the water level detector 60 are entirely submerged in the water stored in the outer tub 20, and the value of the detection signal output from the water level detector 60 in this state, i.e., the voltage value, is set as the reference value. When the pair of electrodes 62 are entirely submerged, the detection signal does not change even if the water level changes. Therefore, the reference value is the value of the detection signal when the water level in the outer tub 20 is at the height of the upper ends of the pair of electrodes 62, i.e., the upper limit water level that the water level detector 60 can detect.

[0077] 6(b), the control unit 101 operates the water level detector 60 and starts acquiring a detection signal from the water level detector 60 (S401). The detection signal is acquired at a predetermined sampling rate, for example, at intervals of 0.1 seconds.

[0078] When a predetermined acquisition time, for example, 15 seconds, has elapsed since the start of acquisition of the detection signal (S402: YES), the control unit 101 stops the operation of the water level detector 60 and ends acquisition of the detection signal (S403).

[0079] The control unit 101 calculates an average value of the acquired detection signals (S404), and stores the calculated average value in the storage unit 102 as a reference value (S405).

[0080] The reference value obtained in the washing step is used in the spin-drying step after the washing step, and the reference value obtained in the rinsing step is used in the spin-drying step after the rinsing step.

[0081] Returning to Fig. 6(a), the control unit 101 calculates a water level judgment value by dividing the average value calculated in S301 by the reference value read out in S302 (S303). The water level judgment value is a value that expresses the water level in the outer tub 20 as a ratio to the upper limit water level that can be detected by the water level detector 60, and takes a value of 1 or less. In this way, the control unit 101 detects the water level in the outer tub 20 in the form of a water level judgment value from the detection signal obtained from the water level detector 60.

[0082] The current flowing through the pair of electrodes 62 differs depending on the conductivity of the water stored in the outer tub 20, even if the water level in the outer tub 20 is the same. The conductivity of the water in the outer tub 20 can change depending on the detergent and dirt components contained in the water. In the first embodiment, as described above, by using the reference value obtained in the washing process or rinsing process immediately before when the same water as that in the spin-drying process was stored, the water level in the outer tub 20 can be detected with high accuracy without being influenced by differences in the conductivity of the water.

[0083] Next, the control unit 101 determines whether or not the water level determination value is greater than a predetermined water level threshold (S304). The water level threshold is set to a value of 0.9, for example.

[0084] When the drainage performance of the drain unit 40 deteriorates due to the accumulation of foreign matter in the drain hose 42, causing a poor drainage state in which the water is not drained smoothly from the outer tub 20, the water drained from the laundry accumulates in the outer tub 20, and the water level in the outer tub 20 rises. This causes the water level judgment value to become greater than the water level threshold value.

[0085] When the control unit 101 determines that the water level determination value is greater than the water level threshold value (S304: YES), it sets a water level abnormality (S305), and thus ends the water level abnormality determination process.

[0086] 7, the control unit 101 divides the acquisition time, excluding an initial predetermined time, into a plurality of intervals (S501). When the acquisition time is 15 seconds, for example, a 12-second period from 3 seconds to 15 seconds is divided into six intervals of 2 seconds each.

[0087] Next, the control unit 101 calculates the difference between the minimum and maximum detection signals, i.e., the voltage values, acquired in each divided section (S502). When the outer tub 20 vibrates, the water in the outer tub 20 ripples, and the water level in the outer tub 20, i.e., the water level of the water present between the pair of electrodes 62, fluctuates. The difference value indicates the magnitude of the fluctuation in the water level.

[0088] The reason why an initial predetermined time of the acquisition time, for example, a time of less than 3 seconds, is excluded from the interval for calculating the difference value is that immediately after the start of operation of the water level detector 60, the detection operation is not stable due to the influence of an inrush current, etc., and the accuracy of the detection signal is low. Therefore, if acquisition of the detection signal is started after the detection operation of the water level detector 60 has stabilized, the initial predetermined time is not necessary.

[0089] Next, the control unit 101 sums up the difference values ​​of the respective sections to obtain a vibration determination value, which is the sum (S503). Then, the control unit 101 determines whether the vibration determination value is greater than a predetermined vibration threshold value (S504).

[0090] When vibrations of such magnitude that water cannot be smoothly drained from the outer tub 20 occur in the outer tub 20, the fluctuations in the water level in the outer tub 20 become large, and the vibration determination value becomes larger than the vibration threshold value.

[0091] When the control unit 101 determines that the vibration determination value is greater than the vibration threshold value (S504: YES), it sets a vibration abnormality (S505), and thus ends the vibration abnormality determination process.

[0092] In addition, in S503, the average value of the difference values ​​of each section may be calculated and the average value may be set as the vibration determination value. In this case, in the judgment in S504, the value obtained by dividing the vibration threshold value when the sum is the vibration determination value by the total number of difference values ​​is set as the vibration threshold value, and the judgment is substantially the same as the judgment in S504 when the sum is the vibration determination value.

[0093] In the first embodiment, the space between the pair of electrodes 62 is a residual water pocket 207, where water tends to accumulate more easily than in the bottom surface portion 202 around the outer tub 20, and when the outer tub 20 vibrates, rippling tends to occur between the pair of electrodes 62. For this reason, the magnitude of vibration of the outer tub 20 is easily detected.

[0094] Returning to Figure 5, when the water level abnormality determination process in Figure 6(a) and the vibration abnormality determination process in Figure 7 are completed, the control unit 101 determines whether or not at least one of the water level abnormality and the vibration abnormality has been set as a result of these abnormality determination processes (S207).

[0095] When at least one of the abnormality settings is made (S207), the control unit 101 determines that a poor drainage condition has occurred in which drainage from the outer tub 20 is not proceeding smoothly, and extends the second maintenance time during which the rotation speed of the washing and spin-drying tub 22 is maintained at the second rotation speed by a predetermined time, for example 10 seconds (S208).

[0096] As described above, the amount of water drained from the laundry decreases as the second maintenance time approaches the end. Therefore, even if a poor drainage state occurs, when the second maintenance time is extended, the rotation speed of the washing and dehydrating tub 22 can be increased from the second rotation speed with the water level in the outer tub 20 lower than when the second maintenance time is not extended. Therefore, even if the centrifugal force acting on the laundry increases and a lot of water is drained from the laundry again, water is prevented from accumulating in the outer tub 20 until it comes into contact with the bottom part 22b of the washing and dehydrating tub 22, and the occurrence of water biting in the washing and dehydrating tub 22 can be reduced.

[0097] <Effects of the First Embodiment> According to this embodiment 1, the fully automatic washing machine 1 includes a pair of electrodes 62 arranged in the space between the bottom portion 202 of the outer tub 20 and the bottom portion 22b of the washing and spin-drying tub 22, and is equipped with a water level detector 60 that detects the current flowing between the pair of electrodes 62, which changes depending on the water level in the outer tub 20, and outputs a detection signal indicating the magnitude of the detected current.The control unit 101 detects the water level in the outer tub 20 based on the detection signal from the water level detector 60 while the rotation of the washing and spin-drying tub 22 is being increased to the spin-drying rotation speed, and when it determines based on the detected water level that a poor drainage condition has occurred in which water is not being drained smoothly from the outer tub 20, it controls the drive motor 31 so that the increase in rotation of the washing and spin-drying tub 22 to the spin-drying rotation speed is slower than when a poor drainage condition does not occur.

[0098] According to this configuration, when poor drainage occurs, the discharge of water from the laundry is suppressed, so that water is prevented from accumulating in outer tub 20 until it contacts bottom surface portion 22b of washing / drying tub 22, and the occurrence of water pinching in washing / drying tub 22 can be reduced. Furthermore, the occurrence of abnormal noise due to water pinching can also be reduced.

[0099] Furthermore, according to this embodiment 1, the control unit 101 rotates the washing and spin-drying tub 22 at a second rotation speed lower than the spin-drying rotation speed, and during that time acquires a detection signal from the water level detector 60 to detect the water level in the outer tub 20, and controls the drive motor 31 so that when a poor drainage condition occurs, the washing and spin-drying tub 22 is rotated at the second rotation speed for a longer time than when a poor drainage condition does not occur.

[0100] According to this configuration, when the water level in the outer tub 20 is low, the rotation speed of the washing and dehydrating tub 22 can be increased from the second rotation speed. Therefore, even if the subsequent increase in rotation speed causes more water to be discharged from the laundry than at the second rotation speed, water is prevented from accumulating in the outer tub 20 until it comes into contact with the bottom portion 22b of the washing and dehydrating tub 22, thereby reducing the occurrence of water biting in the washing and dehydrating tub 22.

[0101] Furthermore, if the drainage performance of the drainage section 40 deteriorates and water does not drain smoothly from the outer tub 20, the water level in the outer tub 20 will increase.

[0102] According to this embodiment 1, the control unit 101 executes the water level abnormality determination process shown in Figure 6(a) to determine whether or not a poor drainage condition has occurred based on the magnitude of the water level detected by the water level detector 60, thereby making it possible to detect the occurrence of a poor drainage condition caused by a deterioration in the drainage performance of the drainage unit 40.

[0103] Furthermore, if the outer tub 20 vibrates strongly, causing the water in the outer tub 20 to sway and preventing smooth drainage, the strong vibration of the outer tub 20 will cause large fluctuations in the water level in the outer tub 20.

[0104] According to this embodiment 1, the control unit 101 executes the vibration abnormality determination process shown in Figure 6 (b) to determine whether or not a poor drainage condition has occurred based on the magnitude of the water level fluctuation detected by the water level detector 60, thereby making it possible to detect the occurrence of a poor drainage condition caused by large vibrations of the outer tank 20.

[0105] <Change Example 1> Fig. 8 is a flowchart showing a water bite prevention control process according to Modification Example 1. Fig. 9(a) is a flowchart showing a water level detection process included in the water bite prevention control process according to Modification Example 1. Fig. 9(b) is a flowchart showing a water level abnormality determination process included in the water bite prevention control process according to Modification Example 1.

[0106] In the fully automatic washing machine 1 of the above embodiment 1, as shown in Figure 5 etc., in the water bite prevention control process, a determination is made as to whether or not a water level abnormality has occurred based on the water level in the outer tub 20 detected while the washing and spin-drying tub 22 is rotating at the second rotation speed.

[0107] In contrast, in the fully automatic washing machine 1 of this modified example 1, as shown in Figure 8, etc., in the water bite prevention control process, a determination is made as to whether or not a water level abnormality has occurred based on the water level in the outer tub 20 detected while the washing and spin-drying tub 22 is rotating at the first rotation speed and the water level in the outer tub 20 detected while the washing and spin-drying tub 22 is rotating at the second rotation speed.

[0108] The following describes changes from the water entrapment prevention control process of the first embodiment.

[0109] 8, control unit 101 monitors whether the rotation speed of washing / drying tub 22 has reached the first rotation speed (S211). When the rotation speed of washing / drying tub 22 has reached the first rotation speed (S211: YES), control unit 101 executes the water level detection process of FIG. 9(a) (S212).

[0110] 9(a), the control unit 101 operates the water level detector 60 and starts acquiring a detection signal from the water level detector 60 (S311). The detection signal is acquired at a predetermined sampling rate, for example, at intervals of 0.1 seconds.

[0111] When a predetermined acquisition time, for example, 15 seconds, has elapsed since the start of acquisition of the detection signal (S312: YES), the control unit 101 stops the operation of the water level detector 60 and ends acquisition of the detection signal (S313).

[0112] Next, the control unit 101 calculates the average value of the acquired detection signals (S314). Furthermore, the control unit 101 reads out the reference value of the detection signals from the storage unit 102 (S315), and divides the average value by the reference value to obtain a first determination value (S316). The first determination value is stored in the storage unit 102.

[0113] Returning to FIG. 8, after the rotation speed of washing and spin-drying tub 22 reaches the second rotation speed, when control unit 101 finishes acquiring the detection signal from water level detector 60 (S201 to S204), in S205, it executes the water level abnormality determination process of FIG. 9(b) instead of the water level abnormality determination process of FIG. 6(a).

[0114] 9(b), the control unit 101 calculates an average value of the acquired detection signals (S321). Furthermore, the control unit 101 reads out a reference value of the detection signals from the storage unit 102 (S322), and divides the average value by the reference value to obtain a second determination value (S323).

[0115] Next, the control unit 101 reads out the first judgment value from the storage unit 102 and adds it to the second judgment value to obtain a water level judgment value (S324). Then, the control unit 101 judges whether the water level judgment value is greater than a predetermined water level threshold value (S325). The water level threshold value is set to a value twice the water level threshold value used in the water level abnormality judgment process of FIG. 6(a), for example, a value of 1.8.

[0116] When the control unit 101 determines that the water level determination value is greater than the water level threshold value (S325: YES), it sets a water level abnormality (S326).

[0117] In addition, in S324, the average value of the first judgment value and the second judgment value may be calculated, and the average value may be used as the water level judgment value. In this case, the water level threshold value for the judgment in S325 is set to the same value as the water level threshold value for the judgment in S304 of Fig. 6(a), and substantially the same judgment is made as in S325 when the sum value is the water level judgment value.

[0118] Furthermore, the first and second judgment values ​​may be compared separately with the water level threshold value of the same value as the judgment in S304 in Fig. 6(a), and if either judgment value is greater than the water level threshold value, a water level abnormality may be set. Also, the value of the water level threshold value to be compared may be different between the first and second judgment values.

[0119] According to the present modified example 1, the water level abnormality is judged taking into consideration the water level in the outer tub 20 when the laundry is being dewatered at the first rotation speed. Therefore, it is possible to more appropriately judge whether or not a drainage failure has occurred.

[0120] <Change Example 2> FIG. 10 is a flowchart showing a water entrapment prevention control process according to the second modified example.

[0121] In the fully automatic washing machine 1 of the above-mentioned embodiment 1, as shown in FIG. 5, when at least one of the water level abnormality and the vibration abnormality is set in the water bite prevention control process, the second maintenance time is extended.

[0122] In contrast, in the fully automatic washing machine 1 of this modified example 2, as shown in Figure 10, when at least one of a water level abnormality and a vibration abnormality is set in the water bite prevention control process, the acceleration when increasing the rotation speed of the washing and spin-drying tub 22 from the second rotation speed is reduced.

[0123] In the water entrapment prevention control process of the present modified example 2 shown in FIG. 10, instead of the process of S208 of the water entrapment prevention control process of the above-mentioned embodiment 1 shown in FIG. 5, the processes of S222 to S224 are executed.

[0124] 10, in S207, control unit 101 determines whether or not at least one of water level abnormality and vibration abnormality has been set. If no abnormality has been set (S207: NO), control unit 101 sets the acceleration for increasing the rotation speed from the second rotation speed to a first acceleration, for example, 30 rpm / s (S221). As a result, in S109 of the control process in FIG. 4, control unit 101 controls drive motor 31 so that the rotation speed of washing / spinning tub 22 increases to the spin-drying rotation speed at the first acceleration.

[0125] On the other hand, when at least one of the abnormality settings is performed (S207: YES), the control unit 101 sets the acceleration when increasing from the second rotation speed to a second acceleration smaller than the first acceleration, for example, 10 rpm / s (S222). As a result, in S109 of the control process in FIG. 4, the control unit 101 controls the drive motor 31 so that the rotation speed of the washing and spin-drying tub 22 increases at the second acceleration.

[0126] In this way, when the outer tub 20 is in a poor drainage state where the drainage is not performed smoothly, the rotation of the washing and dehydrating tub 22 is started up more slowly from the second rotation speed than when the drainage is not in a poor drainage state, so that the drainage of water from the laundry during the start-up is suppressed. This prevents water from accumulating in the outer tub 20 until it contacts the bottom part 22b of the washing and dehydrating tub 22, and reduces the occurrence of water biting in the washing and dehydrating tub 22.

[0127] Thereafter, the control unit 101 monitors whether the rotation speed of the washing and spin-drying tub 22 has reached a third rotation speed (S223). The third rotation speed is a rotation speed in a medium speed range that is higher than the second rotation speed and lower than the spin-drying rotation speed, and is set to, for example, 500 rpm.

[0128] By the time the rotation speed of the washing / drying tub 22 reaches the third rotation speed, a large amount of water has already been squeezed out of the laundry, so the amount of water coming out of the laundry decreases. Therefore, even if the acceleration is increased, the occurrence of water biting in the washing / drying tub 22 can be reduced.

[0129] Therefore, when the rotation speed of washing / spinning tub 22 reaches the third rotation speed (S223: YES), control unit 101 sets the acceleration to the first acceleration (S224). As a result, in S109 of the control process in FIG. 4, control unit 101 controls drive motor 31 so that the rotation speed increases to the spin-drying rotation speed at the first acceleration.

[0130] As described above, according to the present modified example 2, when a poor drainage state occurs in which the drainage from the outer tub 20 is not performed smoothly, the control unit 101 reduces the acceleration when increasing the rotation speed of the washing and dehydrating tub 22 from the second rotation speed. As a result, less water is discharged from the laundry when the rotation speed increases from the second rotation speed, so that the water is prevented from accumulating in the outer tub 20 until it contacts the bottom surface portion 22b of the washing and dehydrating tub 22, and the occurrence of water biting in the washing and dehydrating tub 22 can be reduced.

[0131] In the above example, when the rotation speed of the washing / drying tub 22 reaches the third rotation speed, the acceleration is changed from the second acceleration to the first acceleration, which is greater than the second acceleration. However, the rotation of the washing / drying tub 22 may be increased to the spin rotation speed while maintaining the second acceleration. In this case, the time required to increase the rotation speed to the spin rotation speed is longer, but the occurrence of water biting in the washing / drying tub 22 can be further reduced.

[0132] The configuration of this modified example 2 can be applied to the configuration of the above modified example 1. In this case, the process of S208 in Fig. 8 is replaced with the processes of S221 to S224 in Fig. 10.

[0133] <Change Example 3> Fig. 11 is a flowchart showing a control process by the control unit 101 in the spin-drying process according to the modified example 3. Fig. 12 is a flowchart showing a vibration prevention control process according to the modified example 3.

[0134] In the fully automatic washing machine 1 of the third modified example, the rotation speed of the washing and spin-drying tub 22 is temporarily maintained at the third rotation speed while being increased from the second rotation speed to the spin-drying rotation speed. Then, at the third rotation speed, a vibration prevention control process is executed to prevent vibration of the outer tub 20 based on the water level detected by the water level detector 60.

[0135] Referring to FIG. 11, when the second maintenance time has elapsed since the control unit 101 maintained the rotation speed of the washing and spin-drying tub 22 at the second rotation speed (S108: YES), the control unit 101 sets the target rotation speed to a third rotation speed, for example, 500 rpm, and increases the rotation speed of the washing and spin-drying tub 22 (S121).

[0136] When the rotation speed of washing / drying tub 22 reaches the third rotation speed (S122: YES), control unit 101 maintains the rotation speed of washing / drying tub 22 at the third rotation speed (S123) and waits for a third maintenance time to elapse from the start of the maintenance (S124). The third maintenance time may be about several tens of seconds.

[0137] When the third maintenance time has elapsed (S124: YES), the control unit 101 sets the target rotation speed to the dehydration rotation speed, and increases the rotation speed of the washing and dehydrating tub 22 (S109).

[0138] In parallel with the control process of FIG. 11, the control unit 101 executes the water entrapment prevention control process of FIG. 5 as well as the vibration prevention control process of FIG.

[0139] 12, control unit 101 monitors whether or not the rotation speed of washing / drying tub 22 has reached a third rotation speed (S601). The third rotation speed corresponds to a second detection rotation speed of the present invention.

[0140] When the rotation speed of washing / drying tub 22 reaches the third rotation speed (S601: YES), control unit 101 operates water level detector 60 and starts acquiring a detection signal from water level detector 60 (S602). The detection signal is acquired at a predetermined sampling rate, for example, at intervals of 0.1 seconds.

[0141] When a predetermined acquisition time, for example, 15 seconds, has elapsed since the start of acquisition of the detection signal (S603: YES), the control unit 101 stops the operation of the water level detector 60 and ends acquisition of the detection signal (S604).

[0142] Next, the control unit 101 calculates the average value of the acquired detection signals (S605). Furthermore, the control unit 101 reads out the reference value of the detection signals from the storage unit 102 (S606), and obtains a judgment value by dividing the average value by the reference value (S607). The judgment value is a value indicating the water level of the water in the outer tank 20 that exists between the pair of electrodes 62 of the water level detector 60.

[0143] Next, the control unit 101 judges whether the judgment value is smaller than a predetermined threshold value (S608). The threshold value is set to a value corresponding to a water level lower than the depth of the remaining water pocket 207, for example, a value of 0.5.

[0144] In a low-speed range such as the second rotation speed, some of the water discharged from the laundry into the outer tub 20 accumulates in the remaining water pocket 207. Normally, even when the rotation of the washing and dewatering tub 22 is increased from the second rotation speed to the third rotation speed, which is a medium-speed range, water remains in the remaining water pocket 207. However, if the outer tub 20 vibrates significantly while the rotation of the washing and dewatering tub 22 is increased from the second rotation speed to the third rotation speed, water is likely to splash out from the remaining water pocket 207, and water remaining in the remaining water pocket 207 can be suppressed.

[0145] When outer tub 20 does not vibrate greatly and sufficient water remains in remaining water pocket 207, the judgment value is equal to or greater than the threshold value. When the judgment value is equal to or greater than the threshold value (S608: NO), control unit 101 sets the dehydration rotation speed to the standard rotation speed, for example, 800 rpm (S609). As a result, in S111 of the control process in FIG. 11, control unit 101 rotates washing / dehydrating tub 22 at the standard rotation speed.

[0146] On the other hand, when water is discharged from the remaining water pocket 207 due to the outer tub 20 vibrating greatly, the judgment value becomes smaller than the threshold value. When the judgment value is smaller than the threshold value (S608: YES), the control unit 101 sets the dehydration rotation speed to a low speed rotation speed lower than the standard rotation speed, for example, 700 rpm (S610). As a result, in S111 of the control process in FIG. 11, the control unit 101 rotates the washing and dehydrating tub 22 at the low speed rotation speed.

[0147] In this way, according to the third modified example, when the rotation of the washing and dehydrating tub 22 is increased to the third rotation speed, i.e., the medium speed range, if it is detected that the outer tub 20 is vibrating significantly due to the water being discharged from the residual water pocket 207, the dehydration rotation speed is lowered. Therefore, it is possible to reduce the vibration of the outer tub 20 when the washing and dehydrating tub 22 rotates at the dehydration rotation speed.

[0148] <Embodiment 2> FIG. 13 is a side cross-sectional view of the periphery of the water level detector 70 in the outer tank 20 according to the second embodiment.

[0149] In the fully automatic washing machine 1 of the second embodiment, a photosensor type water level detector 70 is disposed on the bottom surface 202 of the outer tub 20 instead of the water level detector 60. The other configurations of the fully automatic washing machine 1 are similar to those shown in the above-mentioned first embodiment. The water level detector 70 corresponds to the detection unit of the present invention.

[0150] As shown in Fig. 13, the water level detector 70 is attached from below to a mounting port 206 provided on the bottom surface 202 of the outer tank 20. The water level detector 70 has a cylindrical shape with an upper part 70a having a smaller outer diameter than the lower part 70b, and the upper part 70a is fitted into the mounting port 206. A packing 210 is provided between the lower part 70b and the mounting port 206 to provide a water seal. The tip of the upper part 70a protrudes above the inner surface of the bottom surface 202, and has a groove 71 in the center.

[0151] A light-emitting element 72 and a light-receiving element 73 are arranged inside the tip of the water level detector 70 so as to face each other across a groove 71. On two opposing side walls of the groove 71, windows 74 that transmit light are provided in front of the light-emitting element 72 and the light-receiving element 73.

[0152] The light emitting element 72 and the light receiving element 73 are located in the space between the bottom surface 202 of the outer tub 20 and the bottom surface 22b of the washing and spin-drying tub 22, at a predetermined height from the inner surface of the bottom surface 202. The light emitted from the light emitting element 72 is received by the light receiving element 73. The amount of light received by the light receiving element 73 varies depending on the light transmittance between the light emitting element 72 and the light receiving element 73. The water level detector 70 detects the light transmittance and outputs a detection signal according to the detected transmittance to the control unit 101. In the second embodiment, the detection signal is a voltage signal.

[0153] The water level detector 70 detects the transmittance of air when no water is present at the height of the light-emitting element 72 and the light-receiving element 73. When water is present at the height of the light-emitting element 72 and the light-receiving element 73, the water level detector 70 detects the transmittance of water.

[0154] FIG. 14 is a flowchart showing a water entrapment prevention control process according to the second embodiment.

[0155] In the second embodiment, similarly to the first embodiment, in the spin-drying step, the control unit 101 executes the control process shown in Fig. 5. Furthermore, in parallel with the control process shown in Fig. 5, the control unit 101 executes the water-trapping prevention control process shown in Fig. 14.

[0156] 14, when the rotation speed of washing / spinning tub 22 reaches the second rotation speed (S701: YES), control unit 101 operates water level detector 70, i.e., causes light emitting element 72 to emit light, and starts acquiring a detection signal from water level detector 60 (S702). The detection signal is acquired at a predetermined sampling rate, for example, at intervals of 0.1 seconds.

[0157] When a predetermined acquisition time, for example, 15 seconds, has elapsed since the start of acquisition of the detection signal (S703: YES), the control unit 101 stops the operation of the water level detector 60 and ends acquisition of the detection signal (S704).

[0158] Next, the control unit 101 calculates an average value of the acquired multiple detection signals (S705). The average value of the detection signals indicates the light transmittance between the light emitting element 72 and the light receiving element 73 of the water level detector .

[0159] The control unit 101 determines whether the average value is within a predetermined range from the threshold value (S706). The threshold value is a value indicating the transmittance of water stored in the outer tub 20 in the washing process or rinsing process immediately before the spin-drying process. That is, the control unit 101 operates the water level detector 70 for a predetermined time at the end of the washing process or rinsing process, for example, between the time when the pulsator 24 stops operating and the time when water drainage starts, to obtain a detection signal. The control unit 101 then calculates the average value of the obtained detection signals and determines the calculated average value as the threshold value.

[0160] When poor drainage occurs due to the accumulation of foreign matter in the drain hose 42, causing the outer tub 20 to be unable to smoothly drain water, the water drained from the laundry accumulates in the outer tub 20, causing the water level in the outer tub 20 to rise and resulting in water being present at the height of the light emitting element 72 and the light receiving element 73. As a result, the water level detector 70 detects the transmittance of water, so that the average value of the detection signal falls within a predetermined range from the threshold value.

[0161] When the control unit 101 determines that the average value is within the predetermined range from the threshold value (S706: YES), it determines that a poor drainage state is occurring, and extends the second maintenance time by a predetermined time, for example, 10 seconds (S208).

[0162] The air permeability may be detected by the water level detector 70 when there is no water in the outer tub 20, such as immediately before the start of a washing operation, and the air permeability may be used as the threshold. In this case, if it is determined in S706 that the average value is not within a predetermined range from the threshold, the second maintenance time is extended in S707.

[0163] Furthermore, while washing and spinning tub 22 is rotating at the first rotation speed, control unit 101 may execute the same processes as S702 to S705 to obtain an average value of the detection signal from water level detector 70. In this case, control unit 101 sums or averages the average value obtained at the first rotation speed and the average value obtained at the second rotation speed, and in S706 determines whether the sum or average value is within a predetermined range from a threshold value set for this value.

[0164] Furthermore, the water level detector 70 may be configured to include a pair of electrodes similar to those of the water level detector 60 adjacent to the light emitting element 72 and the light receiving element 73, and to further output a detection signal corresponding to the current flowing between the electrodes. In this case, in the water bite prevention control process of FIG. 14, the control unit 101 acquires a detection signal corresponding to the current, and performs the vibration abnormality determination process of FIG. 6(b). Then, when the control unit 101 determines in S706 that the average value is within a predetermined range from the threshold value, or when a vibration abnormality is set in the vibration abnormality determination process, the control unit 101 extends the second maintenance time in S707. Furthermore, in this case, in the water bite prevention control process of FIG. 14, the control unit 101 may perform the water level abnormality determination process of FIG. 6(a), and may also extend the second maintenance time when a water level abnormality is set in the water level abnormality determination process.

[0165] Furthermore, in this embodiment 2, similar to the above-mentioned modified example 2, the processing of S707 in FIG. 14 may be replaced with the processing of S221 to S224 in FIG. 10, so that the acceleration when increasing the rotation speed from the second rotation speed is changed depending on the determination in S706.

[0166] <Effects of the second embodiment> According to this embodiment 2, the fully automatic washing machine 1 includes a light-emitting element 72 and a light-receiving element 73 located at a predetermined height from the bottom portion 202 of the outer tub 20 in the space between the bottom portion 202 of the outer tub 20 and the bottom portion 22b of the washing and spin-drying tub 22, and is equipped with a water level detector 70 that detects the light transmittance between the light-emitting element 72 and the light-receiving element 73 and outputs a detection signal according to the detected transmittance, and the control unit 101 detects whether or not water is present at the predetermined height based on the detection signal from the water level detector 70 while the washing and spin-drying tub 22 is being brought up to the spin-drying rotation speed, and when water is present at the predetermined height, controls the drive motor 31 so that the start-up of the rotation of the washing and spin-drying tub 22 is slower than when water is not present at the predetermined height.

[0167] According to this configuration, when poor drainage occurs, the discharge of water from the laundry is suppressed, so that water is prevented from accumulating in outer tub 20 until it contacts bottom surface portion 22b of washing / drying tub 22, and the occurrence of water pinching in washing / drying tub 22 can be reduced. Furthermore, the occurrence of abnormal noise due to water pinching can also be reduced.

[0168] <Other changes> In the above-mentioned embodiment 1, in the water bite prevention control process of Fig. 5, both the water level abnormality determination process of Fig. 6(a) and the vibration abnormality determination process of Fig. 6(b) are executed. However, in the water bite prevention control process, only one of the water level abnormality determination process and the vibration abnormality determination process may be executed.

[0169] Furthermore, in the above-mentioned embodiment 1, a residual water pocket 207 is provided on the bottom surface 202 of the outer tub 20, and a pair of electrodes 62 of the water level detector 60 protrude upward from the bottom surface of the residual water pocket 207. However, a configuration in which the residual water pocket 207 is not provided on the bottom surface 202 of the outer tub 20 may be adopted. In this case, it is preferable to adopt a configuration in which the pair of electrodes 62 of the water level detector 60 protrude upward from the inner surface of the bottom surface 202.

[0170] Furthermore, the water level detector 60 of the above-mentioned embodiment 1 may also be used as a dirt detector that detects dirt on the water accumulated in the washing process based on a change in the current flowing between the pair of electrodes 62. Similarly, the water level detector 70 of the above-mentioned embodiment 2 may also be used as a dirt detector that detects dirt on the water accumulated in the washing process based on a change in the light transmittance between the light emitting element 72 and the light receiving element 73. Furthermore, a sensor including a pair of electrodes, a light emitting element, and a light receiving element may be used as the water level detectors 60, 70, and in this case, dirt on the water in the washing process may be detected by this sensor.

[0171] Furthermore, in the above-mentioned first and second embodiments, an example in which the present invention is applied to a fully automatic washing machine 1 is shown. However, the present invention can also be applied to a fully automatic washer-dryer equipped with a clothes drying function. Furthermore, the present invention can also be applied to a drum-type washing machine and a drum-type washer-dryer that have a horizontal-axis drum as a washing tub.

[0172] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical ideas set forth in the claims. [Explanation of symbols]

[0173] 1. Fully automatic washing machine (washing machine) 10. Chassis 20 Outer tank 22 Washing and spinning tub (washing tub) 31 Drive motor 40 Drainage section 60 Water level detector (detection section) 62 electrodes 70 Water level detector (detection section) 72 Light emitting element 73 Photodetector 101 Control section 207 Water pocket (recess)

Claims

1. an outer tank elastically supported within a housing; A drainage section for draining water from the outer tank; A washing tub that is rotatably disposed in the outer tub and that accommodates laundry; A drive motor for driving the washing tub; A control unit that controls the drive motor to execute a spin-drying process of rotating the washing tub at a predetermined spin-drying rotation speed; A detection unit includes a pair of electrodes arranged in a space between a bottom surface of the outer tub and a bottom surface of the washing tub, detects a current flowing between the pair of electrodes that changes according to a water level in the outer tub, and outputs a detection signal indicating a magnitude of the detected current, The control unit is While the rotation of the washing tub is being increased to the spin-drying rotation speed, the washing tub is rotated at a first detection rotation speed which is lower than the spin-drying rotation speed, and the detection signal is obtained from the detection unit during the rotation to detect the water level; When it is determined based on the detected water level that a poor drainage state in which drainage from the outer tub is not smoothly occurring is occurring, the drive motor is controlled to make the time for rotating the washing tub at the first detection rotation speed longer than when the poor drainage state is not occurring, thereby slowing down the start-up of rotation of the washing tub to the dehydration rotation speed. A washing machine characterized by:

2. An outer tank elastically supported within a housing; A drainage section for draining water from the outer tank; A washing tub that is rotatably disposed in the outer tub and that accommodates laundry; A drive motor for driving the washing tub; A control unit that controls the drive motor to execute a spin-drying process of rotating the washing tub at a predetermined spin-drying rotation speed; A detection unit includes a pair of electrodes arranged in a space between a bottom surface of the outer tub and a bottom surface of the washing tub, detects a current flowing between the pair of electrodes that changes according to a water level in the outer tub, and outputs a detection signal indicating a magnitude of the detected current, The control unit is While the rotation of the washing tub is being increased to the spin-drying rotation speed, the washing tub is rotated at a first detection rotation speed which is lower than the spin-drying rotation speed, and the detection signal is obtained from the detection unit during the rotation to detect the water level; When it is determined based on the detected water level that a poor drainage state in which drainage from the outer tub is not smoothly occurring has occurred, the drive motor is controlled to make the time for rotating the washing tub at the first detection rotation speed longer than when the poor drainage state does not occur, or to slow down the rise in rotation of the washing tub to the dehydration rotation speed by reducing the acceleration when increasing the rotation speed of the washing tub from the first detection rotation speed; A recess is formed in the bottom surface of the outer tank, the recess being recessed from the inner surface of the bottom surface, the pair of electrodes protrude upward from a bottom surface of the recess, The control unit is rotating the washing tub at a second detection rotation speed which is lower than the spin-drying rotation speed and higher than the first detection rotation speed, and detecting the water level by the detection unit during the second detection rotation speed; When the detected water level is lower than a threshold value, the value of the spin-drying rotation speed is reduced. A washing machine characterized by:

3. The washing machine according to claim 1 or 2, The control unit determines whether or not the poor drainage state occurs based on the detected water level. A washing machine characterized by:

4. In the washing machine according to any one of claims 1 to 3, The control unit determines whether or not the poor drainage state occurs based on the magnitude of the detected fluctuation in the water level. A washing machine characterized by:

5. An outer tank elastically supported within a housing; A drainage section for draining water from the outer tank; A washing tub that is rotatably disposed in the outer tub and that accommodates laundry; A drive motor for driving the washing tub; A control unit that controls the drive motor to execute a spin-drying process of rotating the washing tub at a predetermined spin-drying rotation speed; A detection unit includes a pair of electrodes arranged in a space between a bottom surface of the outer tub and a bottom surface of the washing tub, detects a current flowing between the pair of electrodes that changes according to a water level in the outer tub, and outputs a detection signal indicating a magnitude of the detected current, The control unit is While the rotation of the washing tub is being increased to the spin-drying rotation speed, the washing tub is rotated at a first detection rotation speed which is lower than the spin-drying rotation speed, and the detection signal is acquired from the detection unit within a predetermined acquisition period to detect the fluctuation of the water level within the acquisition period; When it is determined based on the magnitude of the detected fluctuation in the water level that a poor drainage state in which drainage from the outer tub is not smoothly occurring is occurring, the drive motor is controlled so that the start-up of rotation of the washing tub up to the dehydration rotation speed is slower than when the poor drainage state is not occurring. A washing machine characterized by:

6. an outer tank elastically supported within a housing; A drainage section for draining water from the outer tank; A washing tub that is rotatably disposed in the outer tub and that accommodates laundry; A drive motor for driving the washing tub; A control unit that controls the drive motor to execute a spin-drying process of rotating the washing tub at a predetermined spin-drying rotation speed; A detection unit includes a light emitting element and a light receiving element located at a predetermined height from the bottom of the outer tub in a space between the bottom of the outer tub and the bottom of the washing tub, detects the light transmittance between the light emitting element and the light receiving element, and outputs a detection signal according to the detected transmittance. The control unit is While the washing tub is being raised up to the spin-drying rotation speed, the washing tub is rotated at a first detection rotation speed lower than the spin-drying rotation speed, and during this time, the detection signal is obtained from the detection unit to detect whether water is present at the predetermined height; When water is present at the predetermined height, the drive motor is controlled to rotate the washing tub at the first detection rotation speed for a longer time than when water is not present at the predetermined height, thereby slowing down the start-up of rotation of the washing tub to the dehydration rotation speed. A washing machine characterized by:

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