washing machine

Abstract

A washing machine comprises: a motor (6), a washing tub (8) having an outer tub (3) and an inner tub (4), a drainage path (15) connected to a drainage port (3G) of the outer tub (3), an overflow path (17) connected to an overflow port (3E) arranged in the outer tub (3) at a position higher than the drainage port (3G), a drainage valve (16) for opening and closing the drainage path (15), a water supply valve (14) for supplying water into the washing tub (8), a water level detection unit for detecting the water level in the washing tub (8), and a microcomputer (21) for executing a washing operation. During the washing operation, the microcomputer (21) ends the rinsing process with the drainage valve (16) closed, and during the tub washing process, the microcomputer (21) raises the water level in the washing tub (8) to a tub washing water level (W3) that is above the overflow port (3E) and below the opening (3D) of the outer tub (3) while the drainage valve (16) is still closed.

Description

Technical Field

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

[0002] The washing machine described in Patent Document 1 below includes: a water tub with a drain port formed at its bottom; a drain hose connected to the drain port; a drain valve for opening and closing the drain hose; and a rotating tub housed in the water tub in a longitudinally axial configuration. The washing machine can perform a tub wash mode for cleaning the water tub and the rotating tub. During the tub spin wash process in the tub wash mode, the rotating tub rotates while the drain valve is open to continuously drain water from the water tub. This causes the water in the water tub and the rotating tub to gradually rise in a mortar-like manner to a level that prevents overflow. The water tub and the rotating tub are cleaned by dehydration caused by the centrifugal force at this time and the water flow generated by the rotation of the rotating tub.

[0003] Not limited to the washing machine of Patent Document 1, in the washing tub of a general washing machine, mold is sometimes generated by using biofilms formed by detergent residues and dirt (hereinafter referred to as "dirt") remaining after the washing operation as nutrients. Since biofilms are mostly generated near the surface of the water stored in the washing tub during the washing operation, in order to prevent the generation of biofilms, that is, the generation of mold, it is necessary to remove the dirt at a higher position in the washing tub. However, when water is always drained from the drain port on the lower side during the rotary washing process of the tub as in Patent Document 1, even if the rotating tub is rotated, the water level in the water tub and the rotating tub is difficult to reach the dirt, so it is difficult to effectively remove the dirt through the water flow. In addition, the dirt that has been removed with great difficulty and is swept into the water flow may be attached to the water tub and the rotating tub again as the water level drops due to the drainage from the drain port.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-2263 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The present invention has been accomplished based on such background, and an object of the present invention is to provide a washing machine capable of effectively cleaning a washing tub.

[0009] Solutions for solving problems

[0010] The present invention is a washing machine comprising: a motor for generating a driving force; a washing tub having an outer tub and an inner tub, the outer tub being capable of storing water and being provided with a drain outlet, an overflow outlet arranged at a position higher than the drain outlet, and an opening arranged at a position higher than the overflow outlet, the inner tub being arranged in the outer tub, receiving the driving force of the motor to rotate, and being provided with a through hole for allowing water to flow between the inner tub and the outer tub and an inlet and outlet opposite to the opening, wherein laundry enters and exits the inner tub via the opening and the inlet and outlet; a drain path connected to the drain outlet to discharge water in the washing tub; an overflow path connected to the overflow outlet to guide water in the washing tub from the overflow outlet to the drain path; a drain valve to open and close the drain path; a water supply unit to supply water to the washing tub; a water level detection unit to detect the water level in the washing tub; and a control unit to control the motor, The drain valve and the water supply part, the detection result of the water level detection part are input into the control part, and the control part performs a washing operation having a cleaning process, a rinsing process and a tub cleaning process, the cleaning process is a process of supplying water into the washing tub through the water supply part and cleaning the laundry in the inner tub, the rinsing process is a process of supplying water into the washing tub through the water supply part and rinsing the laundry in the inner tub after the cleaning process, and the tub cleaning process is a process of cleaning the washing tub after the rinsing process, wherein the control part ends the rinsing process when the drain valve is closed and water is stored in the washing tub, and rotates the inner tub by the motor while the drain valve is still closed during the tub cleaning process, thereby raising the water level in the washing tub to above the overflow port and below the tub cleaning water level of the opening.

[0011] Furthermore, the present invention is characterized in that, during the tub washing process, when the water level in the washing tub exceeds the tub washing water level, the control unit reduces the rotation speed of the motor.

[0012] In addition, the present invention is characterized in that the control unit executes the barrel cleaning process multiple times, and the control unit performs drainage processing to open the drain valve to discharge part of the water in the washing barrel at least in the last stage of the first barrel cleaning process, and the control unit makes the maximum speed of the motor in the barrel cleaning process after the second time higher than the maximum speed of the motor in the first barrel cleaning process.

[0013] Furthermore, the present invention is characterized in that the control unit continuously rotates the motor during the drainage process.

[0014] In addition, the present invention is characterized in that the washing machine includes a receiving unit for receiving a selection regarding the type of laundry, and when the laundry involved in the selection received by the receiving unit is a blanket, the control unit makes at least either the maximum speed of the motor during the tub washing process and the water level in the washing tub at the start of the tub washing process lower than in the case of laundry other than blankets.

[0015] Effects of the Invention

[0016] According to the present invention, in a washing machine, in a washing tub having an outer tub and an inner tub within the outer tub, water provided by a water supply unit flows back and forth between the outer tub and the inner tub through a through hole in the inner tub, thereby being retained in the outer tub and the inner tub, i.e., the entire washing tub. When the drain valve opens the drain path, the water in the washing tub is discharged from the drain port of the outer tub through the drain path. When the water level in the washing tub rises to an overflow port disposed in the outer tub at a position higher than the drain port, water on the water surface side, i.e., the upper side, of the washing tub is guided from the overflow port through the overflow path to the drain path and discharged through the drain path. Washing items enter and exit the inner tub via an opening disposed in the outer tub at a position higher than the overflow port and an inlet and outlet of the inner tub.

[0017] As part of the washing operation, the washing machine's control unit executes a tub cleansing process after the rinsing cycle to clean the wash tub. Specifically, the control unit ends the rinsing process with the drain valve closed and water still in the wash tub. During the subsequent tub cleansing process, while the drain valve remains closed and water is still in the wash tub, the control unit uses the motor to rotate the inner tub. The centrifugal force generated by the inner tub's rotation raises the water level in the wash tub to a tub clean level above the overflow port and below the opening of the outer tub. When the inner tub is rotated without draining water, the water rising to the tub clean level in the wash tub creates a flow that reaches dirt above the overflow port without leaking out of the wash tub through the opening. Therefore, this flow and centrifugal force remove dirt from the wash tub. The removed dirt, along with the water on the surface of the water in the wash tub, is directed from the overflow port through the overflow channel to the drain and discharged, preventing the dirt from re-adhering to the wash tub. This tub cleansing process effectively cleans the wash tub.

[0018] Furthermore, according to the present invention, during the tub washing process, when the water level in the washing tub exceeds the tub washing water level, the control unit reduces the rotation speed of the motor, thereby preventing the water in the washing tub from leaking out of the washing tub through the opening of the outer tub.

[0019] Furthermore, according to the present invention, when performing the tub cleaning process multiple times, the control unit drains a portion of the water from the washing tub by performing a drainage process at least in the final stage of the first tub cleaning process. Furthermore, the control unit causes the maximum rotational speed of the motor in the second and subsequent tub cleaning processes to be higher than the maximum rotational speed of the motor in the first tub cleaning process. In this case, in the second and subsequent tub cleaning processes, a small amount of water is further pushed up by the centrifugal force generated by the high rotation of the inner tub, thereby causing the tub cleaning water level to be higher than the tub cleaning water level in the first tub cleaning process. Therefore, in the second and subsequent tub cleaning processes, among the dirt in the washing tub at a height above the overflow port, the dirt near the opening is removed without omission. By performing multiple tub cleaning processes in this manner, the washing tub can be cleaned more efficiently.

[0020] Furthermore, according to the present invention, the controller continuously rotates the motor to continuously generate water flow during the drainage process between the multiple tub washing processes, thereby entraining dirt removed from the washing tub into the water flow, thereby preventing the dirt from reattaching to the washing tub.

[0021] Furthermore, according to the present invention, when a highly absorbent blanket is used as laundry, the controller lowers at least one of the maximum motor speed during the tub wash cycle and the water level within the wash tub at the start of the tub wash cycle compared to the case of laundry other than blankets. This prevents the water level within the wash tub from rapidly rising during the tub wash cycle during a wash operation involving blankets, thereby preventing water within the wash tub from leaking out of the wash tub through the outer tub opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic longitudinal sectional view of a washing machine according to one embodiment of the present invention.

[0023] Figure 2 This is a block diagram showing the electrical structure of a washing machine.

[0024] Figure 3 This is a flowchart showing a washing operation performed in a washing machine.

[0025] Figure 4 This is a flow chart showing the tub cleaning process in the washing operation.

[0026] Figure 5 It is a time diagram showing multiple barrel washing processes performed consecutively.

[0027] Description of Reference Numerals

[0028] 1: Washing machine; 3: Outer tub; 3D: Opening; 3E: Overflow port; 3G: Drain port; 4: Inner tub; 4D: Inlet and outlet; 4E: Through hole; 6: Motor; 8: Washing tub; 11: Display and operation unit; 13: Water supply line; 14: Water supply valve; 15: Drain line; 16: Drain valve; 17: Overflow line; 21: Microcomputer; 28: Water level detection unit; Q: Laundry; W3: Tub wash water level. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 : is a schematic longitudinal sectional view of a washing machine 1 according to an embodiment of the present invention. Figure 1 The up-down direction in FIG. 2 is referred to as the up-down direction Z of washing machine 1. Within the up-down direction Z, the upper side is referred to as upper side Z1, and the lower side is referred to as lower side Z2. Washing machine 1 includes: a housing 2, which constitutes the outer shell of washing machine 1; an outer tub 3, which is disposed within housing 2; an inner tub 4, which is housed within outer tub 3; a pulsator 5, which is an example of a rotary blade disposed within inner tub 4; a motor 6, which generates a driving force to rotate inner tub 4 and pulsator 5; and a clutch 7, which is an example of a switching unit that switches the transmission destination of the driving force of motor 6. The combination of outer tub 3 and inner tub 4 is referred to as washing tub 8.

[0030] The housing 2 is made of metal, for example, and is shaped like a box. An opening 2B is formed on the upper surface 2A of the housing 2, connecting the inside and outside of the housing 2. A door 10 is provided on the upper surface 2A for opening and closing the opening 2B. A display operation unit 11, such as a liquid crystal operation panel, is provided around the opening 2B of the upper surface 2A. The user of the washing machine 1 can operate the display operation unit 11 to select operating conditions related to the washing operation performed by the washing machine 1 and to instruct the washing machine 1 to start or stop the washing operation. Information for the user is displayed on the display operation unit 11.

[0031] The outer barrel 3 is made of, for example, resin and has a bottomed cylindrical shape. It comprises a generally cylindrical circumferential wall 3A extending in the vertical direction Z; a bottom wall 3B that blocks the hollow portion of the circumferential wall 3A from the lower side Z2; and an annular ring wall 3C that protrudes from the upper edge of the circumferential wall 3A toward the center of the circumferential wall 3A. An opening 3D is provided on the inner side of the annular wall 3C, communicating with the hollow portion of the circumferential wall 3A from the upper side Z1. The opening 3D is opposed to and communicates with the opening 2B of the housing 2 from the lower side Z2. Optionally, a door 12 for opening and closing the opening 3D is provided on the annular wall 3C. An overflow port 3E is provided at the upper portion of the circumferential wall 3A, radially penetrating the circumferential wall 3A. The bottom wall 3B is formed in the shape of a generally horizontally extending circular plate, with a through hole 3F extending through the bottom wall 3B at the center thereof. A drain port 3G is provided on the bottom wall 3B at a position avoiding the through hole 3F. An overflow port 3E is provided at a position higher than the drain port 3G in the outer tub 3 , and an opening 3D is provided at a position higher than the overflow port 3E in the outer tub 3 .

[0032] A water supply line 13 connected to a tap of tap water is connected to the annular wall 3C of the outer tub 3 from the upper side Z1. A water supply valve 14 is provided in the middle of the water supply line 13. The water supply valve 14 is composed of, for example, a solenoid valve. A drain line 15 is connected to the drain port 3G of the bottom wall 3B of the outer tub 3 from the lower side Z2. The drain line 15 is led out of the washing machine 1, i.e., outside the machine. A drain valve 16 is provided in the middle of the drain line 15. The drain valve 16 is opened and closed, for example, by a torque motor (not shown). The water supply valve 14, which is open and in working condition, opens the entire water supply line 13 by opening the middle of the water supply line 13. The water supply valve 14, which is closed and in non-working condition, cuts off the water supply line 13 in the middle by closing the middle of the water supply line 13. The drain valve 16, which is open and in working condition, opens the entire drain line 15 by opening the middle of the drain line 15. The drain valve 16 , which is closed and in an inoperative state, blocks the drain path 15 midway by blocking the drain path 15 .

[0033] When the water supply valve 14 is opened while the drain valve 16 is closed, water is stored in the outer tub 3 by supplying water from the water supply path 13 into the outer tub 3. The water supply path 13 and the water supply valve 14 function as an example of a water supply unit that supplies water to the outer tub 3, i.e., the washing tub 8. When the water supply valve 14 is closed, the water supply stops. When the drain valve 16 is opened, the water in the outer tub 3 is discharged from the drain port 3G to the outside of the machine through the drain path 15. The washing machine 1 also includes an overflow path 17 having one end 17A connected to the overflow port 3E of the circumferential wall 3A and the other end 17B connected to a downstream portion of the drain path 15 farther from the drain port 3G than the drain valve 16.

[0034] The inner tub 4 is made of metal, for example, and is formed into a bottomed cylindrical shape that is one size smaller than the outer tub 3, and can accommodate laundry Q inside. The inner tub 4 is coaxially arranged in the outer tub 3. The inner tub 4 contained in the outer tub 3 can rotate around the axis J that constitutes its central axis and extends in the up-down direction Z. The washing machine 1 in which the inner tub 4, i.e., the washing tub 8, is longitudinally arranged in this manner is a vertical washing machine. The inner tub 4 has: a roughly cylindrical circumferential wall 4A that is arranged in the up-down direction Z; a bottom wall 4B that blocks the hollow portion of the circumferential wall 4A from the lower side Z2; and an annular ring wall 4C that protrudes toward the axis J along the upper end edge of the circumferential wall 4A. The radial direction mentioned above is a radial direction R based on the axis J.

[0035] The inner circumferential surface of the circumferential wall 4A is the inner circumferential surface of the inner tub 4. The circumferential wall 4A is surrounded by the circumferential wall 3A of the outer tub 3. The bottom wall 4B is provided at the lower end of the inner tub 4. The annular wall 4C is opposed to the annular wall 3C of the outer tub 3 from the lower side Z2. An inlet and outlet 4D is provided on the inner side of the annular wall 4C. The inlet and outlet 4D is located at the upper end of the inner tub 4, exposing the hollow portion of the circumferential wall 4A to the upper side Z1. The inlet and outlet 4D is opposed to and communicates with the opening 3D of the outer tub 3 from the lower side Z2. The user puts laundry Q into and takes it out of the inner tub 4 from the upper side Z1 via the open opening 2B, opening 3D, and the inlet and outlet 4D.

[0036] A plurality of through-holes 4E are provided in the circumferential wall 4A and bottom wall 4B of the inner tub 4. Water in the outer tub 3 flows between the outer tub 3 and the inner tub 4 through the through-holes 4E, and is retained in the inner tub 4. Consequently, water is retained in both the outer tub 3 and the inner tub 4, i.e., the entire washing tub 8, with the water level in the outer tub 3 being consistent with the water level in the inner tub 4. It should be noted that the through-holes 4E may be omitted from the circumferential wall 4A, and may be provided only in the bottom wall 4B.

[0037] The bottom wall 4B of the inner tub 4 is formed into a disc shape and extends approximately parallel to the bottom wall 3B of the outer tub 3 at an interval on the upper side Z1. A through hole 4F is provided at the center of the bottom wall 4B, coinciding with the axis J. A tubular support shaft 18 is provided on the bottom wall 4B, surrounding the through hole 4F and extending toward the lower side Z2 along the axis J. The support shaft 18 is inserted through the through hole 3F in the bottom wall 3B of the outer tub 3, with the lower end of the support shaft 18 located further down the bottom wall 3B than the bottom wall 3B.

[0038] The impeller 5 is disc-shaped, centered on the axis J, and is positioned on the bottom wall 4B within the inner tub 4. A plurality of blades 5A are radially arranged on the upper surface of the impeller 5, facing the inlet 4D of the inner tub 4. A rotating shaft 19 is provided on the impeller 5, extending from its center along the axis J toward the lower side Z2. The rotating shaft 19 is inserted through the hollow portion of the support shaft 18, with its lower end positioned at the lower side Z2 relative to the bottom wall 3B of the outer tub 3.

[0039] The motor 6 is an electric motor such as an inverter motor. The motor 6 is disposed in the housing 2 at the lower side Z2 of the outer tub 3. The motor 6 has an output shaft 20 that rotates about an axis J, and the output shaft 20 outputs the generated driving force.

[0040] The clutch 7 is located between the respective lower ends of the support shaft 18 and the rotating shaft 19 and the upper end of the output shaft 20 protruding from the motor 6 to the upper side Z1. The clutch 7 selectively transmits the driving force output by the motor 6 from the output shaft 20 to one or both of the support shaft 18 and the rotating shaft 19. When the driving force from the motor 6 is transmitted to the support shaft 18, the inner barrel 4 receives the driving force of the motor 6 and rotates around the axis J. When the driving force from the motor 6 is transmitted to the rotating shaft 19, the impeller 5 receives the driving force of the motor 6 and rotates around the axis J. The clutch 7 uses a well-known electric transmission mechanism. Alternatively, the above-mentioned torque motor (not shown) can operate the clutch 7.

[0041] Figure 2 This is a block diagram showing the electrical structure of the washing machine 1. The washing machine 1 includes a microcomputer 21 as an example of a water supply unit and a control unit. The microcomputer 21 is built into the housing 2 and includes, for example, a CPU (Central Processing Unit) 22; a memory 23 such as a ROM (Read Only Memory) or a RAM (Random Access Memory); and a timer 24 for timing (see Figure 1 ).

[0042] The motor 6, clutch 7, water supply valve 14, and drain valve 16 are each electrically connected to the microcomputer 21, for example, via a drive circuit 25. The display operation unit 11 is also electrically connected to the microcomputer 21. The microcomputer 21 activates the motor 6 to drive it or deactivates the motor 6 to stop it. The microcomputer 21 can also control the direction of rotation of the motor 6. Therefore, the motor 6 can rotate forward or reverse. The microcomputer 21 switches the transmission destination of the driving force of the motor 6 to one or both of the inner tub 4 and the pulsator 5 by controlling the clutch 7. The microcomputer 21 controls the opening and closing of the water supply valve 14 and the drain valve 16, that is, whether they are activated or deactivated. When the user operates the display operation unit 11 to select operating conditions, etc., the microcomputer 21 receives the selection. The microcomputer 21 controls the display content of the display operation unit 11.

[0043] Washing machine 1 further includes buzzer 26, rotation speed reader 27, and water level detector 28 electrically connected to microcomputer 21. Microcomputer 21 generates a predetermined sound through buzzer 26 to notify the user of the start and end of the washing operation.

[0044] The speed reading device 27 is a device that reads the speed of the motor 6, strictly speaking, reads the speed of the output shaft 20 in the motor 6, and is composed of, for example, a Hall IC. The speed read by the speed reading device 27 is input to the microcomputer 21 in real time. The microcomputer 21 controls the duty cycle of the voltage applied to the motor 6 based on the input speed, thereby controlling the motor 6 to rotate at the desired speed. It should be noted that the respective speeds of the inner barrel 4 and the impeller 5 can be the same as the speed of the motor 6, or can be a value obtained by multiplying a constant specified by the reduction ratio of the clutch 7, etc., by the speed of the motor 6.

[0045] The water level detector 28 is a water level sensor that detects the water level within the outer tub 3, i.e., the water level within the washing tub 8. As an example of the water level detector 28, a pressure-type water level sensor that detects the water level within the washing tub 8 based on the pressure within the washing tub 8 can be used. The water level within the washing tub 8 is not necessarily level throughout the entire area. The water level detector 28 detects the highest level of the water surface as the current water level within the washing tub 8. The current water level within the washing tub 8, i.e., the detection result of the water level detector 28, is input into the microcomputer 21.

[0046] Microcomputer 21 executes the washing operation by controlling the operation of motor 6, clutch 7, water supply valve 14, and drain valve 16. The washing operation includes at least a washing process, in which water is supplied to washing tub 8 by opening water supply valve 14 to wash the laundry Q in inner tub 4; a rinsing process, in which water is supplied to washing tub 8 by opening water supply valve 14 after the washing process to rinse the laundry Q in inner tub 4; and a tub cleaning process, in which washing tub 8 is cleaned after the rinsing process. In this embodiment, two rinsing processes are performed, the first rinsing process being referred to as the first rinsing process, and the second rinsing process being referred to as the second rinsing process. The washing operation in this embodiment also includes a dehydration process, in which the inner tub 4 is rotated to dehydrate the laundry Q. The dehydration process includes an intermediate dehydration process, which is performed midway through the washing process, and a final dehydration process, which is performed at the end of the washing process. It should be noted that washing machine 1 may also be a washer-dryer that performs a drying process after the dehydration process to dry the laundry Q.

[0047] When the user puts the laundry Q into the inner tub 4 and instructs to start the washing operation, the microcomputer 21 starts the washing operation. It should be noted that the user can also put the detergent into the inner tub 4 before or after putting the laundry Q. Figure 3Flowchart, first, the microcomputer 21 detects the amount of laundry Q in the inner tub 4, i.e., the load amount (step S1). As an example of load amount detection, the microcomputer 21 detects the load amount based on the fluctuation of the rotation speed of the motor 6 when the inner tub 4 is rotated at a low speed and steadily. The microcomputer 21 determines the water level to be supplied to the washing tub 8 next, i.e., the washing water level W1 (see FIG. 1 ), based on the previously detected load amount. Figure 1 The relationship between the washing water level W1 and the load amount is obtained in advance through experiments or the like and stored in the memory 23 .

[0048] Then, as part of the water supply process during the washing process, microcomputer 21 continues to open water supply valve 14 to supply water into washing tub 8 (step S2). Since drain valve 16 is closed, the water level in washing tub 8 rises. When the water level in washing tub 8 reaches the previously determined wash water level W1, microcomputer 21 stops the water supply by closing water supply valve 14. This concludes the water supply process.

[0049] Next, in a state where water is stored in the washing tub 8, the microcomputer 21 performs a stirring process. Specifically, the microcomputer 21 switches the clutch 7 as needed so as to transmit the driving force of the motor 6 to the pulsator 5, and then rotates the pulsator 5 by driving the motor 6 (step S3). The pulsator 5 can rotate continuously in the same direction, but in this embodiment, the pulsator 5 is reversed by the intermittent drive of the motor 6, alternating forward and reverse rotations every 1 to 2 seconds. During the stirring process, the laundry Q in the inner tub 4 is stirred and washed by the reversed pulsator 5. It should be noted that the pulsator 5 may also rotate during the water supply process of step S2, whereby the detergent is easily soluble in water. The dirt on the laundry Q is decomposed by the detergent soluble in water. When the prescribed stirring time has passed, the microcomputer 21 ends the stirring process. Thus, the cleaning process ends.

[0050] After the washing process, as an intermediate dehydration process, the microcomputer 21 rotates the inner tub 4 at high speed with the drain valve 16 open (step S4). The laundry Q in the inner tub 4 is dehydrated by the centrifugal force generated by the high-speed rotation. The water that seeps from the laundry Q during dehydration is discharged from the drain 15 to the outside of the machine. In the final stage of the intermediate dehydration process, the microcomputer 21 switches the clutch 7 so that the driving force of the motor 6 is not transmitted to the inner tub 4 and stops the motor 6, so that the inner tub 4 rotates by inertia. At the end of the intermediate dehydration process, the microcomputer 21 closes the drain valve 16.

[0051] Then, as the first rinsing process, the microcomputer 21 performs spray rinsing (step S5). Specifically, the microcomputer 21 sprays water into the inner barrel 4 by intermittently opening the water supply valve 14 while closing the drain valve 16. In this state, the microcomputer 21 rotates the inner barrel 4 at a low speed of, for example, 30 rpm, so that the spray reaches every corner of the laundry Q. As a result, the laundry Q in the inner barrel 4 is rinsed without dead ends. Afterwards, the microcomputer 21 performs the same intermediate dehydration process as step S4 (step S6). It should be noted that each intermediate dehydration process can also be regarded as part of the subsequent rinsing process.

[0052] Next, the microcomputer 21 executes a second rinse cycle. The second rinse cycle is essentially the same as the washing cycle, except that detergent is not present. Specifically, the microcomputer 21 supplies water (step S7) similarly to step S2, then performs a stirring rinse on the laundry Q (step S8) similarly to step S3. Afterward, when the predetermined stirring time has elapsed, the microcomputer 21 stops the motor 6, closing the drain valve 16 and allowing water to accumulate in the wash tub 8, thereby ending the second rinse cycle.

[0053] Next, the microcomputer 21 executes the tub wash process (step S9). Finally, the microcomputer 21 executes the final spin process (step S10), which is similar to the intermediate spin process. However, the rotation conditions of the inner tub 4 may differ between the intermediate spin process and the final spin process. In particular, the maximum rotation speed of the inner tub 4 during the final spin process may be higher than the maximum rotation speed during the intermediate spin process. With the completion of the final spin process, the washing operation ends.

[0054] Next, refer to Figure 4 The flowchart of step S9 is used to illustrate the tub cleaning process. Regarding the tub cleaning process, in addition to the above-mentioned washing water level W1, the water level in the washing tub 8 also has: an overflow water level W2, which is the same height as the overflow opening 3E of the outer tub 3; a tub cleaning water level W3, which is above the overflow water level W2 and below the opening 3D of the outer tub 3; and an abnormal water level W4, which is higher than the tub cleaning water level W3 (refer to Figure 1 The overflow level W2 is higher than the wash water level W1 and, in this embodiment, is set at the same height as the lower end 3H of the overflow port 3E. The tub wash water level W3 does not have to be a fixed level and can fluctuate between the overflow level W2 and the abnormal water level W4. The abnormal water level W4 is set to a certain degree lower than the opening 3D of the outer tub 3. Furthermore, during the tub wash process, the water supply valve 14 is always closed.

[0055] At the beginning of the tub wash process, the microcomputer 21 switches the clutch 7 to transmit the driving force of the motor 6 to the inner tub 4 (step S11). Next, the microcomputer 21 checks the current water level in the wash tub 8 (step S12). If the water level in the wash tub 8 is above the wash water level W1 ("No" in step S12), the microcomputer 21 opens the drain valve 16 to drain the inner tub 4, thereby lowering the water level in the wash tub 8 (step S13).

[0056] If the water level in the washing tub 8 is lower than the washing water level W1 ("Yes" in step S12), at the timing t0, the microcomputer 21 starts the rotation of the inner tub 4 by operating the motor 6 while the drain valve 16 is still closed (step S14). Then, due to the centrifugal force generated by the rotation of the inner tub 4, a vortex is generated in the washing tub 8, and the water surface S in the washing tub 8 is as shown in FIG. Figure 1 As shown by the two-dot chain line, the tub 8 is curved into a U-shape, with the central portion on the inner side of the radial direction R being lower and the outer peripheral portion on the outer side of the radial direction R being higher. As a result, the water level within the washing tub 8 sequentially exceeds the wash water level W1 and the overflow level W2, rising to the tub clean water level W3. Water on the upper side Z1 of the water surface S within the washing tub 8 is then directed from the overflow port 3E through the overflow channel 17 to the drain channel 15, where it is then discharged to the outside of the washing tub.

[0057] During the tub wash process, if the water level in the washing tub 8 exceeds the tub wash water level W3 and reaches the abnormal water level W4 ("Yes" in step S15), the microcomputer 21 reduces the rotation speed of the motor 6 to reduce the water level in the washing tub 8 (step S16). This prevents the water in the washing tub 8 from leaking out of the washing tub 8 through the opening 3D of the outer tub 3.

[0058] When the water level in the washing tub 8 is lower than the abnormal water level W4 ("No" in step S15), the microcomputer 21 checks the water level in the washing tub 8 (step S18) after a predetermined time t1 has elapsed since the rotation start timing t0 of the motor 6 in step S14 ("Yes" in step S17). If the water level in the washing tub 8 is lower than the overflow level W2 ("Yes" in step S18), the microcomputer 21 increases the rotation speed of the motor 6 to raise the water level in the washing tub 8 (step S19). If the water level in the washing tub 8 is at the overflow level W2 ("No" in step S18), the microcomputer 21 maintains the rotation speed of the motor 6 to maintain the water level in the washing tub 8 at the overflow level W2 (step S20).

[0059] The maximum speed of motor 6 during the tub cleaning process is achieved when the water level in tub 8 is maintained at overflow level W2. This maximum speed is set to a speed lower than the resonance point of washing machine 1, for example, below 240 rpm. In this embodiment, the maximum speed is 120 rpm when the water level in tub 8 successfully reaches overflow level W2. The maximum speed is 150 rpm when the motor 6 speed is increased after a predetermined time t1 (step S19). The maximum speed is 70 rpm when the motor 6 speed is reduced due to the water level in tub 8 reaching abnormal level W4 (step S16).

[0060] When the inner tub 4 is rotated without draining water midway, the water flow generated by the water rising to the tub clean water level W3 within the wash tub 8 reaches dirt within the wash tub 8 located above the lower end 3H of the overflow port 3E, preventing it from leaking out of the wash tub 8 through the opening 3D. Dirt located above the lower end 3H is located on the upper portion of the inner circumferential surface of the outer tub 3's circumferential wall 3A and the upper portion of the outer circumferential surface of the inner tub 4's circumferential wall 4A. Therefore, this water flow and centrifugal force completely remove dirt, especially dirt located above the overflow port 3E. The removed dirt is then directed from the overflow port 3E through the overflow channel 17 to the drain channel 15 and discharged, along with the water on the water surface S side within the wash tub 8. This prevents the dirt from reattaching to the wash tub 8. This tub cleansing process effectively cleans the wash tub 8. Furthermore, since the tub cleansing process is performed during each wash cycle, the wash tub 8 can be kept clean for a long time.

[0061] Before starting the washing operation, the user can select the type of laundry Q by operating the display operation unit 11. The microcomputer 21 and the display operation unit 11 function as an example of a receiving unit to receive the selection regarding the type of laundry Q. If the laundry Q selected by the microcomputer 21 is a blanket, the microcomputer 21 makes at least one of the maximum rotation speed of the motor 6 during the tub wash process and the water level in the washing tub 8 at the start of the tub wash process, i.e., the washing water level W1, lower than that for laundry other than blankets. Thus, during the tub wash process in the washing operation for a blanket, which is a highly absorbent laundry Q, the water level in the washing tub 8 can be prevented from rapidly rising to an abnormal water level W4, thereby preventing the water in the washing tub 8 from leaking out of the washing tub 8 through the opening 3D of the outer tub 3.

[0062] When a predetermined time t2, for example, 10 to 20 seconds, has elapsed since the rotation start timing t0 of the motor 6 in step S14 ("Yes" in step S21), the microcomputer 21 opens the drain valve 16 to drain the water from the washing tub 8 as the final stage of the tub cleaning process (step S22). During the drainage process in step S22, the microcomputer 21 continues to rotate the motor 6 at, for example, 30 rpm. This causes a continuous flow of water to be generated within the washing tub 8 during the drainage process, thereby entraining dirt removed from the washing tub 8 into the water flow, thereby preventing the dirt from reattaching to the washing tub 8. The microcomputer 21 then stops the motor 6 (step S23), ending the tub cleaning process.

[0063] The microcomputer 21 may also execute the tub cleaning process multiple times. Figure 5 is a time diagram for the case where two barrel washing processes are performed. Figure 5 In the time chart, the horizontal axis represents the elapsed time, and the vertical axis shows the water level in the washing tub 8, the rotation speed of the motor 6, and the working / non-working state of the drain valve 16 as the detection result of the water level detection unit 28 in order from top to bottom. It should be noted that, Figure 5 t0', t1', t2', W1' and W3' in the second barrel cleaning process correspond to the above-mentioned t0, t1, t2, W1 and W3 in the first barrel cleaning process, respectively.

[0064] The microcomputer 21 opens the drain valve 16 during at least the final stage of the first tub wash cycle (step S22) to drain a portion of the water from the wash tub 8. Furthermore, the microcomputer 21 increases the maximum rotational speed of the motor 6 during the second and subsequent tub wash cycles compared to the maximum rotational speed of the motor 6 during the first tub wash cycle. For example, the maximum rotational speed of the motor 6 during the first tub wash cycle is 70 rpm, while the maximum rotational speed of the motor 6 during the second and subsequent tub wash cycles is 120 rpm.

[0065] In this case, in the second and subsequent barrel washing processes, a small amount of water will be further pushed up by the centrifugal force generated by the high rotation of the inner barrel 4, thereby making the barrel washing water level W3' higher than the barrel washing water level W3 in the first barrel washing process. Therefore, in the second and subsequent barrel washing processes, the dirt near the opening 3D among the dirt at a height above the lower end 3H of the overflow port 3E in the washing barrel 8 can be removed without omission. Through such multiple barrel washing processes, the washing barrel 8 can be cleaned more effectively. It should be noted that in the drainage process (step S22) in the final stage of the final barrel washing process, the water in the washing barrel 8 will be drained until the water level in the washing barrel 8 becomes zero.

[0066] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

[0067] For example, the axis J of the inner tub 4 of the washing machine 1 is arranged to extend vertically along the up-down direction Z in the above-mentioned embodiment (see FIG. Figure 1 ), but the washing machine 1 as a vertical washing machine may also include a structure in which the axis J is arranged in a manner slightly inclined with respect to the up-down direction Z.

Claims

1. A washing machine, characterized in that: include: Motor, which generates driving force; A washing tub having an outer tub and an inner tub, wherein the outer tub can store water and is provided with a drain outlet, an overflow outlet arranged at a position higher than the drain outlet, and an opening arranged at a position higher than the overflow outlet; the inner tub is arranged within the outer tub, receives the driving force of the motor to rotate, and is provided with a through hole for allowing water to flow between the inner tub and the outer tub, and an inlet and outlet opposite to the opening; laundry enters and exits the inner tub via the opening and the inlet and outlet; a drainage channel connected to the drainage port to drain the water in the washing tub; an overflow channel connected to the overflow port to guide the water in the washing tub from the overflow port to the drain channel; A drain valve, for opening and closing the drain path; a water supply unit for supplying water into the washing tub; a water level detection unit for detecting the water level in the washing tub; and a control unit that controls the motor, the drain valve, and the water supply unit; a detection result of the water level detection unit is input into the control unit; and the control unit executes a washing operation having a washing process, a rinsing process, and a tub cleaning process. The washing process is a process of supplying water into the washing tub through the water supply unit and cleaning the laundry in the inner tub; the rinsing process is a process of supplying water into the washing tub through the water supply unit and rinsing the laundry in the inner tub after the washing process; and the tub cleaning process is a process of cleaning the washing tub after the rinsing process. The control unit ends the rinsing process with the drain valve closed and water stored in the washing tub, and rotates the inner tub by the motor during the tub washing process while continuing to close the drain valve, thereby raising the water level in the washing tub to a tub washing water level above the overflow port and below the opening. When the inner tub is rotated without draining water midway, the water flow generated by the water in the washing tub that rises to the tub washing water level reaches the dirt in the washing tub at a height above the overflow port in a manner that does not leak out of the washing tub from the opening.

2. The washing machine according to claim 1, wherein During the tub washing process, when the water level in the washing tub exceeds the tub washing water level, the control unit reduces the rotation speed of the motor.

3. The washing machine according to claim 1 or 2, characterized in that: The control unit executes the barrel cleaning process multiple times. The control unit performs a drainage process of opening the drain valve to drain a portion of the water in the washing tub at least in the last stage of the first tub washing process. The control unit makes the maximum rotation speed of the motor higher in the second and subsequent tub washing processes than in the first tub washing process.

4. The washing machine according to claim 3, characterized in that The control unit continuously operates the motor during the drainage process.

5. The washing machine according to any one of claims 1 to 4, characterized in that The washing machine includes a receiving unit for receiving a selection regarding a type of laundry. When the laundry involved in the selection received by the receiving unit is a blanket, the control unit makes at least either the maximum speed of the motor during the tub washing process and the water level in the washing tub at the start of the tub washing process lower than those for laundry other than a blanket.

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