Washing machine

Abstract

To provide a washing machine capable of determining a rinsing state of laundry with good accuracy, and capable of finishing the laundry in a cleanly rinsed state.SOLUTION: A fully automatic washing machine 1 includes: a control part 301 which executes a washing step of washing laundry using water including a detergent, a rinsing step of rinsing the laundry using water, and a dewatering step of dewatering the laundry by generating centrifugal force by rotation of a washing and dewatering tub; and a conductivity sensor 60 for measuring conductivity of water accumulated at a bottom part of an outer tub. In the dewatering step following the rinsing step, the control part 301 executes a spin-drying conductivity measuring step of measuring conductivity of spin-dried liquid which is dewatered from the laundry and accumulated in the outer tub, by the conductivity sensor 60, and adjusts the number of times of rinsing step on the basis of the conductivity of the spin-dried liquid.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Conventionally, there is known a washing machine that detects the conductivity of the rinsing water (hereinafter referred to as "rinsing water") stored in an outer tub to check the degree of rinsing of laundry and adjusts the number of rinsing steps to prevent insufficient rinsing. An example of such a washing machine is shown in the following Patent Document 1.

[0003] In the washing machine of Patent Document 1, a predetermined amount of rinse water is supplied into the water receiving tub (outer tub) in the rinsing process. As the washing and spin-drying tub rotates, the rinse water in the water receiving tub is pumped to the top of the washing and spin-drying tub through the circulating water passage by a pump, and is sprayed into the inside of the washing and spin-drying tub from a water supply nozzle. The conductivity of the rinse water is detected by a conductivity detection means in the middle of the circulating water passage. If the conductivity is greater than a predetermined value, and the number of repetitions has not reached a predetermined number, the rinsing process is repeated via an intermediate spin-drying process. If the number of repetitions has reached a predetermined number, the rinsing process of the pool rinse is performed. In the pool rinse, water is supplied to the washing and spin-drying tub, i.e., the water receiving tub, to a predetermined water level, and an agitator blade arranged in the washing and spin-drying tub rotates to agitate the laundry. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-308485 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional washing machine that detects the conductivity of the rinse water stored in the outer tub, if the laundry cannot be rinsed properly and the detergent is not smoothly discharged from the laundry into the rinse water, the detected conductivity of the rinse water will be low, and there is a concern that the laundry will be determined to have been sufficiently rinsed even though a lot of detergent remains in the laundry, and the wash cycle will end in an insufficient rinse state.

[0006] In the washing machine of Patent Document 1, for example, if the positioning of the laundry in the washing and spin-drying tub causes the sprayed water to not cover the laundry properly, it may become difficult for the detergent to be smoothly discharged from the laundry into the rinsing water.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a washing machine that can accurately determine the degree to which laundry has been rinsed and can finish washing the laundry in a thoroughly rinsed state. [Means for solving the problem]

[0008] A washing machine according to a main aspect of the present invention includes an outer tub arranged in a housing and storing water, a washing unit including an inner tub and a drive motor arranged in the outer tub and applying a mechanical force based on a torque generated by the drive motor to laundry contained in the inner tub, a control unit that controls the operation of the washing unit to execute a washing operation including a washing process for washing the laundry with water containing detergent, a rinsing process for rinsing the laundry with water, and a dewatering process for dewatering the laundry by generating a centrifugal force by rotating the inner tub, and a conductivity sensor for measuring the conductivity of water accumulated at the bottom of the outer tub. Here, the control unit executes a dewatering conductivity measurement process for measuring the conductivity of the dewatering water squeezed out from the laundry and accumulated in the outer tub with the conductivity sensor in the dewatering process following the rinsing process, and adjusts the number of times of the rinsing process based on the conductivity of the dewatering water.

[0009] For example, when the conductivity of the deliquescence is measured in the spin-drying process following the second rinsing process, the control unit can adjust the number of rinsing processes by adding a rinsing process after the spin-drying process if it determines that rinsing is insufficient based on the conductivity of the deliquescence, and by not adding a rinsing process after the spin-drying process if it determines that rinsing is sufficient based on the conductivity of the deliquescence.

[0010] Alternatively, when the conductivity of the deliquescence is measured in the spin-drying process following the first rinsing process, the control unit can adjust the number of rinsing processes by performing two rinsing processes after the deliquescence process when it determines, based on the conductivity of the deliquescence, that rinsing may be insufficient with one remaining rinsing process, and performing one rinsing process after the deliquescence process when it determines, based on the conductivity of the deliquescence, that rinsing may be sufficient with one remaining rinsing process.

[0011] According to the washing machine of this embodiment, the conductivity of the water that may contain the detergent from the laundry is directly measured, so unlike the case where the conductivity of the rinsing water stored in the outer tub is measured, the amount of detergent remaining in the laundry is reliably reflected in the measured conductivity. This allows the degree of rinsing of the laundry to be accurately determined, and if rinsing is insufficient, the number of rinsing steps can be increased, so that the laundry can be thoroughly rinsed.

[0012] The washing machine according to the present aspect may further include a water supply device including a water supply valve connected to a water faucet and supplying tap water into the outer tub. In this case, the control unit may be configured to operate the water supply device to store tap water in the outer tub, execute a water conductivity measurement step of measuring the conductivity of the tap water with the conductivity sensor, determine the conductivity of the tap water as a reference conductivity, correct the conductivity of the drained water to be smaller as the reference conductivity is larger, and adjust the number of rinse steps based on the corrected conductivity of the drained water.

[0013] According to the above configuration, the conductivity of the drained water is corrected using the reference conductivity, thereby eliminating the effects of differences in the properties of tap water, making it possible to accurately determine the amount of detergent remaining on the laundry.

[0014] When the electrical conductivity of the drainage is corrected using the reference electrical conductivity as described above, the washing machine may be further configured to include a detergent tank for storing liquid detergent and a detergent dispenser for automatically dispensing the detergent in the detergent tank into the outer tub. In this case, the control unit may be configured to operate the detergent dispenser and the water supply device to store water containing detergent in the outer tub during water supply in the washing step, and to execute the water conductivity measurement step before the detergent dispenser dispenses the detergent into the outer tub.

[0015] According to the above configuration, it is possible to prevent the detergent dispensed by the detergent dispenser from being mixed into the tap water measured in the water conductivity measurement process, and it is possible to prevent the conductivity of tap water with a high detergent concentration from being set to the reference conductivity.

[0016] When the drainage conductivity is corrected using the reference conductivity as described above, the control unit may be further configured to store the reference conductivity in the storage unit, and when the conductivity of the tap water measured in the water conductivity measurement step is smaller than the reference conductivity stored in the storage unit, the control unit may be configured to determine the conductivity of the tap water as a new reference conductivity.

[0017] According to the above-mentioned configuration, the smallest conductivity among the conduction water conductivity measured in the water conductivity measuring process is set as the reference conductivity, so that even in a situation where the tap water stored in the outer tub may be affected by the dirt or detergent on the laundry, the conductivity of the conduction water close to the original value is set as the reference conductivity by repeated washing operations. Therefore, it is possible to more accurately determine the amount of detergent remaining on the laundry.

[0018] As described above, when a configuration is adopted in which the drainage conductivity is corrected using a reference conductivity, the control unit can be configured to perform a first water conductivity measurement process before the washing process, perform a second water conductivity measurement process after the dehydration process following the first rinsing process, determine the smaller of the two tap water conductivities measured in the first and second water conductivity measurement processes as the reference conductivity, and perform the drainage conductivity measurement process in the dehydration process following the second rinsing process.

[0019] According to the above configuration, the conductivity of the water conduction measured in the first and second water conductivity measuring steps can be set as the reference conductivity, which is less affected by laundry dirt and detergent and is closer to the original value. Therefore, it is possible to more accurately determine the amount of detergent remaining in the laundry.

[0020] When the electrical conductivity of the drainage is corrected using the reference electrical conductivity as described above, the electrical conductivity sensor may include a pair of electrodes arranged to protrude upward from the inner surface of the bottom part of the outer tank. In this case, the control unit may be configured to monitor the rate of change of the electrical conductivity measured by the electrical conductivity sensor in the water electrical conductivity measurement step, and determine the electrical conductivity after the rate of change becomes equal to or less than a specified value as the electrical conductivity of the tap water, and to monitor the rate of change of the electrical conductivity measured by the electrical conductivity sensor in the drainage electrical conductivity measurement step, and determine the electrical conductivity after the rate of change becomes equal to or less than the specified value as the electrical conductivity of the drainage.

[0021] According to the above configuration, the conductivity measured when the pair of electrodes is completely submerged is determined to be the conductivity of tap water and the conductivity of the deliquescence, so that the conductivity of the tap water itself and the conductivity of the deliquescence itself can be accurately measured.

[0022] In the washing machine according to this aspect, the washing operation may include at least two rinse steps, an intermediate spin-dry step following the first rinse step, and a final spin-dry step following the second rinse step, in which the inner tub rotates at a higher spin-dry speed and for a longer spin-dry time than in the intermediate spin-dry step. In this case, the control unit may be configured to execute the dehydration conductivity measuring step in the final spin-dry step, and when adding the rinsing step based on the dehydration conductivity, to change the spin-dry speed to a lower value and / or the spin-dry time to a shorter value in the final spin-dry step being executed, and to execute the final spin-dry step after the added rinsing step.

[0023] According to the above configuration, the time required for the final spin-drying step before the added rinsing step can be shortened, and the increase in the time required for the washing operation due to the addition of the rinsing step and the final spin-drying step can be suppressed. Effect of the Invention

[0024] According to the present invention, a washing machine can be provided that can accurately determine the degree of rinsing of laundry and can finish rinsing the laundry thoroughly.

[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 an embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a water supply device according to an embodiment. [Diagram 3] Fig. 3(a) is a plan cross-sectional view of an outer tank according to an embodiment, and Fig. 3(b) is a side cross-sectional view of the outer tank and the periphery of a conductivity sensor taken along line AA' in Fig. 3(a) according to an embodiment. [Figure 4] FIG. 4 is a block diagram showing a configuration of a fully automatic washing machine according to an embodiment. [Diagram 5] FIG. 5 is a flowchart showing a control process by the control unit during a washing operation according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing a control process by the control unit in a water conductivity measuring step included in a washing operation according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing a control process by the control unit in a drainage conductivity measuring step included in a washing operation according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing a control process by the control unit during a washing operation according to the first modified example. [Figure 9] FIG. 9 is a flowchart showing a control process by the control unit in a rinse addition determination step included in a washing operation according to the first modified example. [Figure 10] FIG. 10 is a flowchart showing a control process by the control unit during a washing operation according to the second modified example. 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] FIG. 1 is a side cross-sectional view of a fully automatic washing machine 1. As shown in FIG.

[0029] The fully automatic washing machine 1 has a housing 10 that forms an outer shell. The housing 10 includes a rectangular cylindrical body 11 with open top and bottom faces, a top panel 12 that covers the top face of the body 11, and a foot stand 13 that supports the body 11. A laundry inlet 14 is formed in the top panel 12. The laundry inlet 14 is covered by a top lid 15 that can be opened and closed freely. A control unit 16 is disposed inside and in front of the top panel 12. The control unit 16 controls the washing operation performed by the fully automatic washing machine 1.

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

[0031] A washing / dehydrating tub 22 is disposed within the outer tub 20. The washing / dehydrating tub 22 is cylindrical with a bottom, opens upward, and rotates around a rotation axis extending vertically. A large number of dehydration holes 22a are formed around the entire inner circumferential surface of the washing / dehydrating tub 22. In addition, a large number of discharge holes 22b are formed in the inner bottom surface of the washing / dehydrating tub 22.

[0032] A balance ring 23 is provided on the top of the washing / drying tub 22. A pulsator 24 is disposed on the bottom of the washing / drying tub 22. A plurality of blades 24a are provided radially on the surface of the pulsator 24. The washing / drying tub 22 corresponds to the "inner tub" of the present invention.

[0033] A drive unit 30 is disposed on the outside of the bottom surface 202 of the outer tub 20, generating torque for driving the washing and spin-drying tub 22 and the pulsator 24. 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 and spin-drying tub 22 to rotate the pulsator 24 and the washing and spin-drying tub 22 integrally in the spin-drying step.

[0034] Washing / spinning tub 22, pulsator 24, and drive unit 30 constitute a washing unit WU. In washing unit WU, drive motor 31 rotates pulsator 24 to generate a water flow in washing / spinning tub 22, and thereby applies a mechanical force based on the torque generated by drive motor 31 to the laundry accommodated in washing / spinning tub 22.

[0035] A drain outlet 203 is formed in the bottom surface 202 of the outer tub 20. A drain valve 40 is provided in the drain outlet 203. The drain valve 40 includes, for example, a valve and a torque motor that opens and closes the valve. A drain hose 41 is connected to the drain valve 40. When the drain valve 40 is opened, water stored in the washing and spin-drying tub 22 and the outer tub 20 is drained outside the machine through the drain hose 41.

[0036] The outer tub 20 is provided with a water level detection unit 50 that detects the water level in the outer tub 20. The water level detection unit 50 includes an air trap 51 formed at the bottom of the outer tub 20, and a water level sensor 53 connected to the air trap 51 via a hose 52. The water level sensor 53 is a diaphragm-type water level sensor, and detects the water level in the outer tub 20 by detecting the air pressure in the air trap 51, which changes depending on the water level in the outer tub 20.

[0037] A water supply device 100 is disposed at the rear of the top panel 12. The water supply device 100 is connected to a water faucet and has a function of supplying water to the washing and spin-drying tub 22, i.e., the outer tub 20. Tap water is supplied to the outer tub 20 from the water supply device 100. Furthermore, the water supply device 100 also has a function of automatically putting liquid detergent into the washing and spin-drying tub 22, i.e., the outer tub 20.

[0038] FIG. 2 is a diagram showing a schematic configuration of the water supply device 100. As shown in FIG.

[0039] The water supply device 100 includes a water supply valve unit 110, a water inlet portion 120, a first water supply passage 130, a second water supply passage 140, a three-way valve 150, a pump 160, and a detergent tank 170.

[0040] The water supply valve unit 110 is a so-called double valve, and has a first water supply valve 111 and a second water supply valve 112. A water inlet 113 of the water supply valve unit 110 is connected to a water faucet via a water supply hose (not shown). The rated flow rate of the first water supply valve 111 is greater than the rated flow rate of the second water supply valve 112. The first water supply valve 111 and the second water supply valve 112 correspond to the "water supply valves" of the present invention.

[0041] Water inlet section 120 is formed in a box shape, and is located above the rear part of washing / drying tub 22. Water inlet 121 that opens downward is formed in the bottom surface of water inlet section 120. As shown in FIG. 1, water inlet 121 is located above the rear end part of washing / drying tub 22, and faces the inside of washing / drying tub 22.

[0042] The first water supply passage 130 and the second water supply passage 140 are disposed between the water supply valve unit 110 and the water inlet portion 120. The first water supply passage 130 has an upstream end connected to the first water supply valve 111, and a downstream end connected to the water inlet portion 120. The second water supply passage 140 has an upstream end connected to the second water supply valve 112, and a downstream end connected to the water inlet portion 120.

[0043] The three-way valve 150 is disposed in the second water supply passage 140. The pump 160 is, for example, a piston pump, and is disposed in the second water supply passage 140 downstream of the three-way valve 150.

[0044] Liquid detergent is stored in the detergent tank 170. An inlet 171 is formed in the upper surface of the detergent tank 170. A filter (not shown) that captures foreign matter entering through the inlet 171 is attached to the inlet 171. A discharge portion 172 that protrudes downward is formed in the bottom surface of the detergent tank 170. A cylindrical discharge port 173 is formed on the periphery of the discharge portion 172. A supply pipe 180 is connected to the discharge port 173. The detergent tank 170 is connected to the three-way valve 150 via the supply pipe 180.

[0045] The second water supply valve 112, the second water supply passage 140, the three-way valve 150, the pump 160 and the detergent tank 170 constitute a detergent dispenser 100a.

[0046] When supplying water into outer tub 20, first water supply valve 111 and second water supply valve 112 are opened. This causes water supply device 100 to discharge water from above washing / dehydrating tub 22 into washing / dehydrating tub 22.

[0047] When detergent dispenser 100a dispenses detergent into washing / drying tub 22, i.e., outer tub 20, during water supply, three-way valve 150 is switched to a state in which supply pipe 180 communicates with the downstream side of three-way valve 150 in second water supply passage 140. Next, pump 160 is operated, and air on the upstream side of pump 160 in second water supply passage 140 is sucked in, creating negative pressure on the upstream side. As a result, liquid detergent in detergent tank 170 is sucked in and sent into second water supply passage 140 via supply pipe 180, as shown by the dashed line in FIG. 2. An amount of detergent according to the operation time of pump 160 accumulates in second water supply passage 140.

[0048] Next, three-way valve 150 is switched to a state in which the upstream side and downstream side of three-way valve 150 in second water supply passage 140 are in communication with each other. Second water supply valve 112 is opened, and water from a water faucet is supplied into second water supply passage 140, as shown by the solid arrow in FIG. 2. The water flowing through second water supply passage 140 washes away the detergent accumulated in second water supply passage 140. The detergent washed away by the water flows together with the water into water inlet portion 120, and is poured into washing and spin-drying tub 22 from water inlet 121.

[0049] Fig. 3(a) is a plan cross-sectional view of the outer tank 20. Fig. 3(b) is a side cross-sectional view of the outer tank 20 around the conductivity sensor 60, taken along line AA' in Fig. 3(a).

[0050] 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. 3. 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.

[0051] 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 60 is attached to the mounting hole 206.

[0052] The conductivity sensor 60 has a cylindrical shape with an upper portion 60a having a smaller outer diameter than the lower portion 60b, and the upper portion 60a is fitted into the mounting port 206. A packing 210 is provided between the lower portion 60b and the mounting port 206 to provide a water seal. The tip of the upper portion 60a protrudes above the inner surface of the bottom portion 202, and has a groove portion 61 in the center. The bottom surface of the groove portion 61 is lower than the inner surface of the bottom portion 202 around the mounting port 206, and the portion of the groove portion 61 lower than the inner surface of the bottom portion 202 becomes a residual water pocket 207 recessed from the inner surface of the bottom portion 202.

[0053] Conductivity sensor 60 has a pair of electrodes 62 provided on two opposing side wall surfaces of groove portion 61. The pair of electrodes 62 have a rectangular plate shape and are disposed in the space between bottom portion 202 and washing / dehydrating tub 22 so as to protrude upward from the bottom surface of residual water pocket 207, which is part of the inner surface of bottom portion 202.

[0054] The conductivity sensor 60 is used to measure the conductivity of tap water supplied from the water supply device 100 into the outer tub 20 and the conductivity of water squeezed out from the laundry in the spin-drying process (hereinafter referred to as "dehydrated water"). When a voltage is applied to a pair of electrodes 62 and tap water or dehydrated water accumulates between the two electrodes 62, a current having a magnitude (value) according to the conductivity of the tap water or dehydrated water flows between the electrodes 62. The conductivity sensor 60 outputs a signal according to the current value to the control unit 301 as a conductivity signal indicating the conductivity.

[0055] FIG. 4 is a block diagram showing the configuration of the fully automatic washing machine 1. As shown in FIG.

[0056] In addition to the above-mentioned configuration, the fully automatic washing machine 1 includes an operation unit 70 and a display unit 80. The control unit 16 also includes a control unit 301, a memory unit 302, a motor drive unit 303, a clutch drive unit 304, a water supply valve drive unit 305, a three-way valve drive unit 306, a drain valve drive unit 307, and a pump drive unit 308.

[0057] The operation unit 70 includes various operation buttons such as a power button for turning the power on and off, a start button for starting a washing operation, and a course selection button for selecting an operation course, and outputs operation signals corresponding to these operation buttons to the control unit 301.

[0058] The display unit 80 includes a plurality of LEDs and a 7-segment display, and in accordance with control signals from the control unit 301, displays the operation course, the progress and remaining time of the washing operation, and displays various errors.

[0059] Water level sensor 53 outputs a water level signal to control unit 301 according to the water level in washing and spin-drying tub 22, i.e., in outer tub 20.

[0060] The motor driving unit 303 drives the driving motor 31 in accordance with a control signal output from the control unit 301. The motor driving unit 303 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 301. Furthermore, the motor driving unit 303 includes a current detection circuit that detects the current flowing through the driving motor 31.

[0061] The clutch driving unit 304 drives the clutch mechanism 32 a of the transmission mechanism unit 32 in accordance with a control signal output from the control unit 301 .

[0062] The water supply valve driving unit 305 drives the first water supply valve 111 and the second water supply valve 112 in accordance with a control signal from the control unit 301 .

[0063] The three-way valve driving unit 306 drives the three-way valve 150 in accordance with a control signal from the control unit 301 .

[0064] The drain valve driving unit 307 drives the drain valve 40 in accordance with a control signal from the control unit 301 .

[0065] The pump driving unit 308 drives the pump 160 in accordance with a control signal from the control unit 301 .

[0066] The storage unit 302 includes an EEPROM, a RAM, etc. Programs for executing various operation courses of the washing operation are stored in the storage unit 302. In addition, various operation conditions used in the washing operation are stored in the storage unit 302.

[0067] The control unit 301 includes a CPU, etc., and controls the display unit 80, motor drive unit 303, clutch drive unit 304, water supply valve drive unit 305, three-way valve drive unit 306, drain valve drive unit 307, pump drive unit 308, etc. in accordance with programs stored in the memory unit 302 based on signals from the operation unit 70, water level sensor 53, conductivity sensor 60, etc.

[0068] In the fully automatic washing machine 1, various operation courses of the washing operation are performed under the control of the control unit 301. The washing operation includes a washing process, a rinsing process, and a spin-drying process. The spin-drying process includes an intermediate spin-drying process performed in the middle of the washing operation and a final spin-drying process performed at the end of the washing operation.

[0069] In this embodiment, in the final spin-drying step following the rinsing step, a dewatering conductivity measuring step is performed in which the conductivity of the dewatered liquid squeezed out of the laundry and accumulated in the outer tub 20 is measured by the conductivity sensor 60. Then, the amount of detergent remaining in the laundry is determined based on the measured conductivity of the dewatered liquid. If the conductivity of the dewatered liquid is high because a large amount of detergent remains in the laundry, a rinsing step is added after the final spin-drying step.

[0070] The conductivity of the drainage may vary depending not only on the amount of detergent remaining in the laundry but also on the properties of the water contained in the laundry, i.e., tap water. The properties of tap water may differ depending on the region. For example, when tap water is hard water containing a large amount of calcium ions and magnesium ions, the conductivity is higher than when tap water is soft water containing fewer of these ions. Therefore, in this embodiment, in order to eliminate the influence of differences in the properties of tap water, a water conductivity measurement process is performed to measure the conductivity of tap water supplied from the water supply device 100. Then, the conductivity of the tap water is determined as a reference conductivity, and whether or not to add a rinsing process is determined based on the conductivity of the drainage corrected by the reference conductivity.

[0071] Fig. 5 is a flowchart showing the control process by the control unit 301 in the washing operation. Fig. 6 is a flowchart showing the control process by the control unit 301 in the water conductivity measuring step included in the washing operation. Fig. 7 is a flowchart showing the control process by the control unit 301 in the drainage conductivity measuring step included in the washing operation.

[0072] After putting laundry into washing and spin-drying tub 22, the user operates operation unit 70 to start the washing operation.

[0073] 5, when the washing operation is started, the control unit 301 first executes a load amount detection step for detecting the load amount of laundry in the washing and spinning tub 22 (S101). That is, the control unit 301 operates the drive motor 31 to rotate the pulsator 24, and determines the load amount based on the drive current of the drive motor 31 and the amount of inertial rotation until the drive motor 31 stops. The larger the load amount is, the larger the drive current is, and the smaller the amount of inertial rotation is. The control unit 301 sets the amount of water to be supplied in the washing process and the rinsing process (washing water level, rinsing water level) and the amount of detergent to be dispensed in the washing process according to the detected load amount. The larger the load amount is, the larger the amount of water to be supplied and the amount of detergent to be dispensed are.

[0074] Next, the control unit 301 executes a first water conductivity measuring step for measuring the conductivity of tap water supplied by the water supply device 100 (S102).

[0075] 6, control unit 301 opens first water supply valve 111 and second water supply valve 112 to start water supply by water supply device 100 to outer tub 20 (S201). Tap water is discharged from water inlet 121 of water supply device 100 into washing and spin-drying tub 22. After dripping onto laundry contained in washing and spin-drying tub 22, the tap water flows out from spin-drying holes 22a and discharge holes 22b of washing and spin-drying tub 22 and accumulates at the bottom of outer tub 20.

[0076] The control unit 301 measures the conductivity using the conductivity sensor 60 at regular sampling time intervals, for example, at intervals of 0.1 seconds, and monitors whether the rate of change in conductivity has reached a specified value or not by comparing the conductivity measured previously with the conductivity measured this time (S202 to S204).

[0077] The pair of electrodes 62 of the conductivity sensor 60 are arranged to protrude upward from the inner bottom surface of the outer tub 20, so they gradually become submerged as tap water accumulates. Until the pair of electrodes 62 are completely submerged, the surface area of ​​the electrodes 62 that are in contact with the tap water changes, so the magnitude of the current flowing between the electrodes changes, and the conductivity changes. For this reason, the conductivity of the tap water itself cannot be measured accurately.

[0078] When the pair of electrodes 62 is completely submerged, the measured conductivity stops changing and the rate of change reaches a specified value or less. When the control unit 301 determines that the rate of change in conductivity has reached a specified value or less (S203: YES), it determines the currently measured conductivity, i.e., the conductivity immediately after it reaches a specified value or less, as the conductivity of tap water (hereinafter referred to as "water conductivity") (S205). This allows the conductivity of the tap water itself to be measured accurately.

[0079] The conductivity may be measured multiple times after the rate of change becomes equal to or less than the specified value, and the average value of the multiple conductivities may be determined as the water conductivity.

[0080] When the water conductivity is measured in this manner, the first water conductivity measuring process is completed. The water supply device 100 continues to supply water to the outer tub 20.

[0081] 5, when the first water conductivity measuring step is completed, the control unit 301 checks whether or not the reference conductivity is stored in the memory unit 302 (S103). If the reference conductivity is stored in the memory unit 302 (S103: YES), the control unit 301 determines whether or not the water conductivity measured in the water conductivity measuring step is smaller than the reference conductivity (S104).

[0082] If the reference conductivity is not stored in the memory unit 302 (S103: NO), or if the water conductivity is smaller than the reference conductivity stored in the memory unit 302 (S104: YES), the control unit 301 determines the water conductivity as a new reference conductivity and stores the new reference conductivity in the memory unit 302 (S105).

[0083] On the other hand, when the water conductivity is equal to or higher than the reference conductivity stored in the storage unit 302 (S104: NO), the control unit 301 maintains the reference conductivity stored in the storage unit 302.

[0084] Next, the control unit 301 executes the washing process (S106 to S108). First, the control unit 301 performs a water supplying operation to store water containing detergent in the outer tub 20 (S106). The control unit 301 closes the second water supply valve 112 and keeps the first water supply valve 111 open. The water supply device 100 continues to supply water from the first water supply valve 111. Furthermore, the control unit 301 operates the detergent supply device 100a to supply the detergent into the outer tub 20 in an amount set according to the load amount. Note that when the detergent is supplied, the second water supply valve 112 is opened, and the open state is maintained even after the detergent is supplied. After that, when the water level in the outer tub 20 reaches the washing water level set according to the load amount, the control unit 301 closes the first water supply valve 111 and the second water supply valve 112 to stop the water supply.

[0085] Next, the control unit 301 performs the washing operation (S107). The control unit 301 operates the drive motor 31 to rotate the pulsator 24 alternately to the right and left with stops in between. The rotation of the pulsator 24 generates a water flow in the washing and spin-drying tub 22, and the laundry is washed by the force of the water flow, i.e., the mechanical force and the detergent force. The control unit 301 stops the pulsator 24 when a predetermined washing time has elapsed.

[0086] Next, the control unit 301 performs a draining operation by opening the drain valve 40 (S108). The water containing detergent stored in the outer tub 20 is drained outside the machine through the drain hose 41. When a certain time has passed since the lowest water level was detected by the water level detection unit 50 and the water in the outer tub 20 has been completely drained, the washing process ends. The drain valve 40 remains open.

[0087] If the detergent dispenser 100a is set not to dispense detergent automatically, the detergent dispenser 100a does not operate during the water supply operation in the washing step. In this case, the user manually dispenses detergent into the washing and spin-drying tub 22 during the water supply operation, etc.

[0088] Next, control unit 301 executes an intermediate spin-drying step (S109). Control unit 301 operates drive motor 31 to rotate washing / spin-drying tub 22 together with pulsator 24 at a high speed at a predetermined spin-drying rotation speed (e.g., 800 rpm). At this time, control unit 301 gradually increases the rotation speed of washing / spin-drying tub 22 up to the spin-drying rotation speed. That is, control unit 301 performs steady rotation for a certain period of time at a first rotation speed (e.g., 120 rpm) and a second rotation speed (e.g., 240 rpm) higher than the first rotation speed during the increase in the rotation speed.

[0089] The laundry is pressed against the inner peripheral surface of the washing / dehydrating tub 22 by the centrifugal force generated by the rotation of the washing / dehydrating tub 22, and water is squeezed out of the laundry. The liquid drained from the laundry is discharged into the outer tub 20 through the dehydration holes 22a, and is then discharged outside the machine through the drain hose 41.

[0090] When a predetermined spin-drying time has elapsed since the rotation speed of washing / drying tub 22 reaches the spin-drying rotation speed, control unit 301 stops washing / drying tub 22. This ends the intermediate spin-drying process. Drain valve 40 remains open.

[0091] In addition, the dehydration time does not have to be the time from when the rotation speed of the washing and dehydrating tub 22 reaches the dehydration rotation speed to when the washing and dehydrating tub 22 is stopped, but may be the time from when the rotation of the washing and dehydrating tub 22 starts to when it is stopped.

[0092] Next, the control unit 301 executes a shower rinsing process as a first rinsing process (S110). In the shower rinsing process, the control unit 301 opens the first water supply valve 111 and the second water supply valve 112 to allow the water supply device 100 to supply water into the washing and spin-drying tub 22, and operates the drive motor 31 to rotate the washing and spin-drying tub 22 together with the pulsator 24 at a low speed.

[0093] Tap water discharged from the water inlet 121 of the water supply device 100 is sprayed onto the laundry that has been brought to the inner peripheral side of the washing and dewatering tub 22 by the intermediate dewatering process. As the laundry absorbs the water sufficiently, the water that is not absorbed by the laundry flows out from the laundry together with the detergent. This causes the laundry to be rinsed.

[0094] When a predetermined rinsing time has elapsed, control unit 301 stops washing and spin-drying tub 22. This ends the shower rinsing process.

[0095] Next, the control unit 301 executes an intermediate spin-drying process (S111). The detergent remaining in the laundry is discharged together with the water sufficiently contained in the laundry by the shower rinsing process. Thus, the laundry is spun and rinsed. When the intermediate spin-drying process is completed, the drain valve 40 is closed.

[0096] Next, the control unit 301 executes a second water conductivity measuring step (S112), whereby the water conductivity is measured in the same manner as in the first water conductivity measuring step.

[0097] The control unit 301 determines whether the water conductivity measured in the second water conductivity measuring step is smaller than the reference conductivity (S113). If the water conductivity is smaller than the reference conductivity stored in the memory unit 302 (S114: YES), the control unit 301 determines the water conductivity as a new reference conductivity and stores the new reference conductivity in the memory unit 302 (S114). On the other hand, if the water conductivity is equal to or greater than the reference conductivity stored in the memory unit 302 (S113: NO), the control unit 301 maintains the reference conductivity stored in the memory unit 302.

[0098] The tap water supplied from the water supply device 100 is stored in the outer tub 20 via the washing and spin-drying tub 22. Therefore, the tap water is likely to come into contact with the laundry stored in the washing and spin-drying tub 22, and dirt adhering to the laundry is likely to mix with the tap water. Therefore, in the first water conductivity measuring step performed before the washing step, the tap water stored in the outer tub 20 is likely to contain dirt, and the measured water conductivity is likely to be affected by the amount of dirt. Furthermore, if detergent is manually added before the first water conductivity measuring step, the measured water conductivity is likely to be affected by the detergent.

[0099] On the other hand, in the second water conductivity measuring step performed after the intermediate spin-drying step following the first rinsing step, the soil on the laundry has been removed in the washing step, so the measured water conductivity is less affected by the amount of soil compared to the first water conductivity measuring step. Furthermore, when detergent is manually dispensed, the water conductivity measured in the first water conductivity measuring step is easily affected by the detergent, so the effect of the detergent on the water conductivity in the second water conductivity measuring step may be smaller than that in the first water conductivity measuring step. Note that, when detergent is automatically dispensed by the detergent dispenser 100a, the water conductivity measured in the first water conductivity measuring step is less affected by the detergent, so the effect of the detergent on the water conductivity in the second water conductivity measuring step may be larger than that in the first water conductivity measuring step, since the detergent used in the washing step may remain.

[0100] For these reasons, when the tap water stored in the outer tub 20 is unlikely to contain laundry dirt or when detergent is automatically added manually, the water conductivity measured in the first water conductivity measuring step may be smaller than the water conductivity measured in the second water conductivity measuring step. On the other hand, when the tap water stored in the outer tub 20 is likely to contain laundry dirt or when detergent is automatically added manually, the water conductivity measured in the second water conductivity measuring step may be smaller than the water conductivity measured in the first water conductivity measuring step.

[0101] In this embodiment, the control unit 301 executes the processes of steps S103 to S105 and S112 to S114 to determine the smaller of the two water conductivities measured in the first and second water conductivity measuring steps as the reference conductivity. This allows the water conductivity (tap water conductivity) that is less affected by laundry stains and detergent and is closer to the original value to be set as the reference conductivity.

[0102] Furthermore, in this embodiment, when the water conductivity measured in the water conductivity measuring process is smaller than the reference conductivity stored in the memory unit 302, the control unit 301 determines the water conductivity as a new reference conductivity. As a result, the smallest water conductivity among the water conductivities measured in the first and second water conductivity measuring processes is set as the reference conductivity. Therefore, even in a situation where the tap water stored in the outer tub 20 may be affected by laundry stains or detergent, a water conductivity (tap water conductivity) that is less affected by laundry stains and detergent and is closer to the original value is set as the reference conductivity by repeated washing operations.

[0103] Next, the control unit 301 executes a reservoir rinsing process as the second rinsing process (S115 to S117). First, the control unit 301 performs a water supplying operation to store water in the outer tub 20 (S115). The control unit 301 keeps the first water supply valve 111 and the second water supply valve 112 open and continues the water supply to the outer tub 20 that was started in the second water conductivity measuring process. When the water level in the outer tub 20 reaches the rinsing water level set according to the load amount, the control unit 301 closes the first water supply valve 111 and the second water supply valve 112 to stop the water supply.

[0104] Next, the control unit 301 performs the pool rinse operation (S116). The control unit 301 operates the drive motor 31 to rotate the pulsator 24 alternately to the right and left with stops in between. The rotation of the pulsator 24 generates a water flow in the washing and spin-drying tub 22, and the laundry is rinsed by the force of the water flow. As a result, the detergent remaining on the laundry is discharged. The control unit 301 stops the pulsator 24 when a predetermined rinse time has elapsed.

[0105] Next, the control unit 301 performs a draining operation by opening the drain valve 40 (S117). When the water in the outer tub 20 is completely drained, the pooling and rinsing process ends. The drain valve 40 remains open.

[0106] Next, the control unit 301 executes the final spin-drying process (S118). The control unit 301 operates the drive motor 31 to rotate the washing / spin-drying tub 22 together with the pulsator 24 at a predetermined high-speed spin-drying rotation speed. In the final spin-drying process, the spin-drying rotation speed is set to be higher than that in the intermediate spin-drying process (for example, 1000 rpm). As in the intermediate spin-drying process, the control unit 301 gradually increases the rotation speed of the washing / spin-drying tub 22 up to the spin-drying rotation speed. The liquid removed from the laundry is discharged into the outer tub 20 through the spin-drying holes 22a of the washing / spin-drying tub 22.

[0107] In the final spin-drying process, a spin-drying time is set longer than that in the intermediate spin-drying process. When the spin-drying time has elapsed since the spin-drying rotation speed was reached, the control unit 301 stops the washing and spin-drying tub 22. This ends the final spin-drying process. When the final spin-drying process ends, the drain valve 40 is closed.

[0108] The control unit 301 executes a drained water conductivity measuring step in which the conductivity of the drained water squeezed out of the laundry and accumulated in the outer tub 20 is measured by the conductivity sensor 60 in the final spin-drying step (S119).

[0109] 7, the control unit 301 closes the drain valve 40 (S301). This makes it easier for the dehydrated liquid discharged into the outer bath 20 to accumulate at the bottom of the outer bath 20.

[0110] The control unit 301 measures the conductivity using the conductivity sensor 60 at a fixed sampling time interval, for example, 0.1 second intervals, and compares the conductivity measured previously with the conductivity measured this time to monitor whether the rate of change in conductivity has reached a specified value or less (S302 to S304). The pair of electrodes 62 of the conductivity sensor 60 are gradually submerged in water as the drained liquid accumulates in the outer bath 20.

[0111] When the pair of electrodes 62 are completely submerged, the measured conductivity stops changing and the rate of change reaches a specified value or less. When the control unit 301 determines that the rate of change of the conductivity has reached a specified value or less (S303: YES), it determines the currently measured conductivity, i.e., the conductivity immediately after it reaches a specified value or less, as the conductivity of the drainage (hereinafter referred to as the "drainage conductivity") (S305). This allows the conductivity of the drainage itself to be measured accurately.

[0112] The conductivity after the rate of change becomes equal to or less than the specified value may be measured multiple times, and the average value of the multiple conductivities may be determined as the drainage conductivity.

[0113] The control unit 301 opens the drain valve 40 (S306). As a result, the dehydrated liquid discharged into the outer tub 20 is discharged outside the apparatus via the drain hose 41.

[0114] The drainage conductivity measuring process is thus completed. The drainage conductivity measuring process is started at the same time that the rotation of the washing and dewatering tub 22 is started, and is completed at least by the time the rotation speed of the washing and dewatering tub 22 reaches the dewatering rotation speed.

[0115] Returning to FIG. 5, after the removal conductivity measurement process is completed, and further after the final spin-drying process is completed, the control unit 301 corrects the removal conductivity measured in the removal conductivity measurement process by using the reference conductivity stored in the memory unit 302. That is, the control unit 301 obtains the corrected removal conductivity (hereinafter referred to as the "corrected conductivity") by subtracting the reference conductivity from the removal conductivity (S120). For a given removal conductivity, the corrected conductivity becomes smaller as the reference conductivity becomes larger. The corrected conductivity is a value that accurately reflects the amount of detergent remaining on the laundry, removing the effects of differences in the properties of tap water.

[0116] Next, the control unit 301 judges whether or not the corrected conductivity is greater than a predetermined threshold value (S121). When a large amount of detergent remains in the laundry and rinsing is insufficient, the corrected conductivity becomes greater than the threshold value.

[0117] If the corrected conductivity is equal to or lower than the threshold value (S121: NO), it can be determined that there is no insufficient rinsing, and therefore the control unit 301 ends the washing operation without adding an additional rinsing step.

[0118] On the other hand, if the corrected conductivity is greater than the threshold value (S121: YES), it can be assumed that rinsing is insufficient, and so control unit 301 executes a pool rinse process as an additional rinsing process. That is, control unit 301 executes a water supply operation, a pool rinse operation, and a drainage operation (S122 to S124). This resolves the insufficient rinsing of the laundry.

[0119] When the additional rinsing step is completed, the control unit 301 executes a final spin-drying step (S125) and then ends the washing operation.

[0120] <Effects of the embodiment> According to this embodiment, the control unit 301 executes a dehydration conductivity measurement step in which the conductivity of the dehydration liquid squeezed out of the laundry and accumulated in the outer tub 20 is measured by the conductivity sensor 60 in the dehydration step following the rinsing step, and adjusts the number of rinsing steps based on the conductivity of the dehydration liquid. Specifically, the control unit 301 measures the conductivity of the dehydration liquid in the final dehydration step, and if it determines that rinsing is insufficient based on the conductivity of the dehydration liquid, it adds a rinsing step after the final dehydration step, and if it determines that rinsing is sufficient based on the conductivity of the dehydration liquid, it does not add a rinsing step after the final dehydration step.

[0121] According to this configuration, the conductivity of water that may contain detergent from the laundry is directly measured, so the amount of detergent remaining in the laundry is reliably reflected in the measured conductivity, unlike when the conductivity of rinsing water stored in the outer tub 20 is measured. This makes it possible to accurately determine how well the laundry has been rinsed, and to add more rinsing steps if rinsing is insufficient, thereby enabling the laundry to be thoroughly rinsed.

[0122] Furthermore, according to this embodiment, the control unit 301 operates the water supply device 100 to store tap water in the outer tub 20, executes a water conductivity measurement step in which the conductivity of the tap water is measured by the conductivity sensor 60, and determines the conductivity of the tap water to be the reference conductivity. Then, the control unit 301 corrects the conductivity of the drained water so that it becomes smaller as the reference conductivity is larger, and adjusts the number of rinsing steps based on the corrected conductivity of the drained water.

[0123] According to this configuration, the conductivity of the drained water is corrected using the reference conductivity, thereby eliminating the effects of differences in the properties of tap water, making it possible to accurately determine the amount of detergent remaining on the laundry.

[0124] Furthermore, according to this embodiment, when supplying water in the washing step, the control unit 301 operates the detergent dispenser 100a and the water supplying device 100 to store water containing detergent in the outer tub 20. Then, the control unit 301 executes the first water conductivity measuring step before the detergent is dispensed into the outer tub 20 by the detergent dispenser 100a.

[0125] This configuration prevents the detergent dispensed by the detergent dispenser 100a from being mixed into the tap water measured in the first water conductivity measurement process, and prevents the conductivity of tap water with a high detergent concentration from being set to the reference conductivity.

[0126] Furthermore, according to this embodiment, the control unit 301 stores the reference conductivity in the memory unit 302, and when the conductivity of the tap water measured in the water conductivity measurement process is smaller than the reference conductivity stored in the memory unit 302, the control unit 301 determines the conductivity of the tap water to be the new reference conductivity.

[0127] According to this configuration, the smallest conductivity of the water conduction measured in the water conductivity measurement process is set as the reference conductivity, so even if the tap water stored in the outer tub 20 is affected by the dirt on the laundry or detergent, the conductivity of the water conduction close to the original value is set as the reference conductivity by repeated washing operations. Therefore, it is possible to more accurately determine the amount of detergent remaining on the laundry.

[0128] Furthermore, according to this embodiment, the control unit 301 executes a first water conductivity measuring step before the washing step, and executes a second water conductivity measuring step after the spin-drying step (intermediate spin-drying step) following the first rinsing step.The control unit 301 then determines the smaller of the two tap water conductivities measured in the first and second water conductivity measuring steps as the reference conductivity, and executes a drainage conductivity measuring step in the spin-drying step (final spin-drying step) following the second rinsing step.

[0129] According to this configuration, of the two tap water conductivities measured in the first and second water conductivity measuring steps, the tap water conductivity that is less affected by laundry dirt and detergent and is closer to the original value can be set as the reference conductivity, making it possible to more accurately determine the amount of detergent remaining in the laundry.

[0130] Furthermore, according to this embodiment, the conductivity sensor 60 includes a pair of electrodes 62 arranged to protrude upward from the inner surface of the bottom portion 202 of the outer tank 20. Then, in the water conductivity measurement process, the control unit 301 monitors the rate of change of the conductivity measured by the conductivity sensor 60, and determines the conductivity after the rate of change becomes equal to or less than a specified value as the conductivity of tap water. Furthermore, in the removal conductivity measurement process, the control unit 301 monitors the rate of change of the conductivity measured by the conductivity sensor 60, and determines the conductivity after the rate of change becomes equal to or less than the specified value as the conductivity of removal.

[0131] According to this configuration, the conductivity measured when the pair of electrodes 62 is completely submerged is determined to be the conductivity of tap water and the conductivity of the dehydrated water, so that the conductivity of the tap water itself and the conductivity of the dehydrated water itself can be accurately measured.

[0132] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications of the embodiment of the present invention are possible.

[0133] <Change Example 1> In the above embodiment, after the final spin-drying step is completed, it is determined whether or not to add a rinsing step based on the conductivity of the drained water.

[0134] In contrast, in this modified example, in the final spin-drying step, it is determined whether or not to add a rinse step based on the electrical conductivity of the dehydrated water. Furthermore, if it is determined that a rinse step should be added, the spin-drying speed is lowered and / or the spin-drying time is shortened in the final spin-drying step being performed.

[0135] Fig. 8 is a flowchart showing a control process by the control unit 301 in a washing operation according to Modification 1. Fig. 9 is a flowchart showing a control process by the control unit 301 in a rinse addition determination step included in the washing operation according to Modification 1.

[0136] 8, when the drainage conductivity measuring step is completed in the final spin-drying step (S119), the control unit 301 executes an additional rinsing determination step (S126).

[0137] 9, the control unit 301 corrects the drainage conductivity measured in the drainage conductivity measurement step by using the reference conductivity stored in the storage unit 302. That is, the control unit 301 obtains a corrected conductivity by subtracting the reference conductivity from the drainage conductivity (S401). Then, the control unit 301 determines whether the corrected conductivity is greater than a threshold value (S402).

[0138] If the corrected conductivity is equal to or lower than the threshold value (S402: NO), it can be determined that there is no insufficient rinsing, and therefore the control unit 301 ends the additional rinsing determination process.

[0139] On the other hand, if the corrected conductivity is greater than the threshold value (S402: YES), it can be assumed that rinsing is insufficient, and therefore the control unit 301 sets an additional flag (S403). The additional flag is provided in the control unit 301, for example.

[0140] Furthermore, the control unit 301 changes the spin rotation speed of the final spin water step to a lower value, and also changes the spin time of the final spin water step to a shorter value (S404). For example, the spin rotation speed and spin time are changed to those of the intermediate spin water steps. In this case, the final spin water step is essentially changed to the intermediate spin water step. Thereafter, the control unit 301 ends the rinse addition determination process. Note that the rinse addition determination process ends at least before the rotation speed of the washing and spin water tub 22 reaches the spin water rotation speed.

[0141] Note that the control unit 301 may change only either the spin rotation speed or the spin time in the final spin step.

[0142] Returning to Fig. 8, after the rinse addition determination step is completed, and further after the final spin-dry step is completed, the control unit 301 determines whether or not the addition flag is set (S127). If the addition flag is not set (S127: NO), the control unit 301 ends the washing operation. On the other hand, if the addition flag is not set (S127: NO), the control unit 301 executes a pool rinse step as an additional rinse step (S122-S124), and then executes a final spin-dry step (S125), and ends the washing operation.

[0143] According to the configuration of this modified example, when a rinse step is added and a final rinse step is executed again after the rinse step, the spin rotation speed is changed to be lower and / or the spin time is changed to be shorter in the final spin step before the added rinse step. This makes it possible to shorten the time required for the final spin step before the added rinse step, and to suppress the increase in the time of the washing operation due to the addition of the rinse step and the final spin step.

[0144] <Change Example 2> In the above embodiment, the control unit 301 measures the conductivity of the dehydration in the final spin-drying process, and if it determines that the rinsing is insufficient based on the conductivity of the dehydration, it adds a rinsing process after the final spin-drying process, and if it determines that the rinsing is sufficient based on the conductivity of the dehydration, it does not add a rinsing process after the final spin-drying process.

[0145] In contrast, in this modified example, the control unit 301 measures the conductivity of the deliquescence in the intermediate spin-drying step following the first rinsing step, and if it determines based on the conductivity of the deliquescence that rinsing may be insufficient in the one remaining rinsing step, it performs two rinsing steps after the intermediate spin-drying step, and if it determines based on the conductivity of the deliquescence that rinsing may be sufficient in the one remaining rinsing step, it performs one rinsing step after the intermediate spin-drying step.

[0146] FIG. 10 is a flowchart showing the control process by the control unit 301 during a washing operation according to the second modified example.

[0147] 10, when the shower rinsing process, which is the first rinsing process, is completed (S110), the control unit 301 performs an intermediate spin-drying process (S130). Furthermore, the control unit 301 executes a drainage conductivity measuring process in the intermediate spin-drying process (S131) ​​to measure the drainage conductivity.

[0148] After the removal conductivity measurement step is completed, when the intermediate spinning step is also completed, the control unit 301 obtains a corrected conductivity by subtracting the reference conductivity from the removal conductivity (S132), and determines whether the corrected conductivity is greater than a predetermined threshold value (S133). The threshold value in this modification is set to be greater than the threshold value in the above embodiment.

[0149] If the corrected conductivity is greater than the threshold value (S133: YES), the remaining rinse step may not be sufficient for rinsing, so the control unit 301 executes two rinse steps by sequentially executing a pool rinse step (S134-S136), an intermediate spin-dry step (S137), a pool rinse step (S138-S140), and a final spin-dry step (S141).

[0150] On the other hand, if the corrected conductivity is equal to or lower than the threshold value (S133: NO), the one remaining rinse step may be sufficient for rinsing, so the control unit 301 sequentially executes the pool rinse step (S138 to S140) and the final spin-dry step (S141) to perform one rinse step.

[0151] As with the above embodiment, the configuration of this modified example makes it possible to accurately determine the degree to which the laundry has been rinsed, and if the rinsing is insufficient, the number of rinsing steps can be increased, thereby enabling the laundry to be thoroughly rinsed.

[0152] In this modified example, the detergent dispenser 100a of the water supply device 100 may include, as the liquid dispenser, a fabric softener tank in which liquid fabric softener is stored, in addition to the detergent tank 170. The fabric softener tank is connected to the second water supply passage 140 via a three-way valve, similar to the detergent tank 170. In this case, the fabric softener in the fabric softener tank may be automatically dispensed into the outer tub 20 in the final rinsing step (pooling rinsing step) executed before the final spin-drying step.

[0153] <Other changes> In the above embodiment, the water conductivity measurement process is performed twice, that is, before the washing process and after the intermediate spin-dry process following the rinsing process. However, the water conductivity measurement process may be performed only once, either before the washing process or after the intermediate spin-dry process following the rinsing process. When the water conductivity measurement process is performed only once, as in the above embodiment, when the water supplying device 100 is provided with a detergent dispenser 100a that automatically dispenses the detergent in the detergent tank 170, it is preferable that the water conductivity measurement process is performed before the washing process. On the other hand, when the water supplying device 100 is provided with a detergent case in the middle of the water supply path to the outer tub 20, into which a single dose of detergent is dispensed, and when tap water always passes through the detergent case when water is supplied from the water supplying device 100, it is preferable that the water conductivity measurement process is performed after the intermediate spin-dry process following the rinsing process so that the detergent dispensed from the detergent case into the outer tub 20 does not affect the water conductivity measurement process.

[0154] Furthermore, in the above embodiment, a shower rinsing step is executed as the first rinsing step. However, a pool rinsing step may be executed as the first rinsing step. However, when a shower rinsing step is executed as the first rinsing step, insufficient rinsing is more likely to occur than when a pool rinsing step is executed, so it is very meaningful for the fully automatic washing machine 1 to have a function for adjusting the number of rinses based on the conductivity of the liquid drained from the laundry.

[0155] Furthermore, the configuration and arrangement of the conductivity sensor 60 are not limited to those in the above embodiment, and any configuration and arrangement may be used as long as the conductivity of the water retained in the outer tank 20 and the drained water can be measured.

[0156] Furthermore, the configuration of the detergent dispenser 100a is not limited to that of the above embodiment. For example, the detergent dispenser 100a may not be included in the water supplying device 100, but may be provided separately from the water supplying device 100.

[0157] Furthermore, in the above embodiment, an example in which the present invention is applied to a fully automatic washing machine 1 has been 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 shaft type drum as an inner tub inside an outer tub. In a drum type washing machine and a drum type washer-dryer, a washing unit is formed by a drum and a drive motor that rotates the drum, and the drum rotates to tumble the laundry, thereby applying a mechanical force to the laundry.

[0158] 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]

[0159] 1. Fully automatic washing machine (washing machine) 10. Chassis 20 Outer tank 22 Washing and spinning tub (inner tub) 31 Drive motor 60 Conductivity Sensor 62 electrodes 100 Water supply equipment 100a Detergent dispenser 111 First water supply valve (water supply valve) 112 Second water supply valve (water supply valve) 170 Detergent tank 202 Bottom part 301 Control Unit 302 Storage section WU Washing Unit

Claims

1. an outer tank disposed within the housing and configured to store water; a washing unit including an inner tub and a driving motor disposed in the outer tub, the washing unit applying a mechanical force based on a torque generated by the driving motor to laundry contained in the inner tub; a control unit that controls an operation of the washing unit to execute a washing operation including a washing process for washing laundry with water containing detergent, a rinsing process for rinsing the laundry with water, and a dewatering process for dewatering the laundry by generating centrifugal force through rotation of the inner tub; a conductivity sensor for measuring the conductivity of the water accumulated at the bottom of the outer tank; The control unit is a drainage conductivity measuring step of measuring the conductivity of drainage liquid squeezed out from the laundry and accumulated in the outer tub by the conductivity sensor in the dewatering step subsequent to the rinsing step; Adjusting the number of rinse steps based on the conductivity of the drained liquid. A washing machine characterized by:

2. The washing machine according to claim 1, The water supply device further includes a water supply valve connected to a water faucet and supplies tap water into the outer tub. The control unit is A water conductivity measuring step is carried out in which tap water is stored in the outer tank by operating the water supply device and the conductivity of the tap water is measured by the conductivity sensor; The conductivity of the tap water is determined as a reference conductivity; The electrical conductivity of the drained liquid is corrected so as to be smaller as the reference electrical conductivity is larger; adjusting the number of rinse steps based on the corrected conductivity of the drained water; A washing machine characterized by:

3. The washing machine according to claim 2, The washing machine further includes a detergent tank for storing a liquid detergent, and a detergent dispenser for automatically dispensing the detergent in the detergent tank into the outer tub. The control unit is When supplying water in the washing step, the detergent dispenser and the water supplying device are operated to store water containing detergent in the outer tub; The water conductivity measuring step is performed before the detergent is dispensed into the outer tub by the detergent dispenser. A washing machine characterized by:

4. The washing machine according to claim 2 or 3, A storage unit is further provided, The control unit is storing the reference conductivity in the storage unit; When the conductivity of the tap water measured in the water conductivity measuring step is smaller than the reference conductivity stored in the memory unit, the conductivity of the tap water is determined to be a new reference conductivity. A washing machine characterized by:

5. The washing machine according to claim 2, The control unit is A first water conductivity measuring step is carried out before the washing step; A second water conductivity measuring step is carried out after the first rinsing step and the subsequent dehydration step; determining the smaller of the two conductivity values ​​of the tap water measured in the first and second water conductivity measuring steps as the reference conductivity; The dewatering conductivity measuring step is carried out in the dewatering step following the second rinsing step. A washing machine characterized by:

6. The washing machine according to claim 2, the electrical conductivity sensor includes a pair of electrodes arranged to protrude upward from an inner surface of a bottom portion of the outer tank, The control unit is In the water conductivity measuring step, a rate of change in the conductivity measured by the conductivity sensor is monitored, and the conductivity after the rate of change becomes equal to or less than a specified value is determined as the conductivity of the tap water; In the drainage conductivity measuring step, a rate of change in the conductivity measured by the conductivity sensor is monitored, and the conductivity after the rate of change becomes equal to or less than the specified value is determined as the drainage conductivity. A washing machine characterized by:

7. The washing machine according to claim 1, The washing operation includes at least two rinsing steps, an intermediate spin-drying step following a first rinsing step, and a final spin-drying step following a second rinsing step in which the inner tub is rotated at a higher spin-drying speed for a longer spin-drying time than in the intermediate spin-drying step, The control unit is The dewatering conductivity measuring step is carried out in the final dewatering step, When the rinsing step is added based on the electrical conductivity of the drained water, the spinning speed is changed to be lower and / or the spinning time is changed to be shorter in the final spinning step being performed; performing the final spin-drying step after the additional rinsing step; A washing machine characterized by:

Images