Drum washing machine

Abstract

To provide a drum-type washing machine capable of satisfactorily suppressing propagation of black mold and the like to a drum by using ozone water.SOLUTION: A drum-type washing machine 1 includes: an outer tub 20 disposed inside a housing 10; a drum 23 disposed inside the outer tub 20 and rotatable around a horizontal axis; a drive motor 30 for rotating the drum 23; an ozone water supply part 60 for supplying ozone water into the outer tub 20; and a control part for performing tub cleaning operation. In the tub cleaning operation, the control part performs a tub cleaning process in which: the ozone water is stored in the outer tub 20 by the ozone water supply part 60 in such an amount that the ozone water can be in contact with the drum 23; and the drum 23 is rotated by the drive motor 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a drum-type washing machine. Such a drum-type washing machine may be one that performs washing and drying continuously, or one that performs washing but does not perform drying. [Background technology]

[0002] In drum-type washing machines, biofilms are likely to form on the outer surface of the drum and the inner surface of the outer tub, which can easily lead to the growth of black mold, etc. Therefore, in order to remove the biofilms and suppress the growth of black mold, etc., drum-type washing machines can be configured to perform a tub cleaning operation.

[0003] For example, the following Patent Document 1 describes a drum-type washing machine that, during the tub cleaning operation, creates a high-temperature, high-humidity environment inside the tub by spraying water into the outer tub and supplying warm air heated by a heater into the tub, thereby killing bacteria and mold that live on the surface of the tub and drum.

[0004] Incidentally, there is known a drum-type washing machine that disinfects laundry using ozone water, which is made by dissolving ozone in water, as shown in the following Patent Document 2. Therefore, it is conceivable to perform a tub cleaning operation using the disinfection effect of ozone water, rather than using the disinfection effect of heat as in Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-039836 [Patent Document 2] Japanese Patent Publication No. 2020-103566 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a drum-type washing machine that can effectively suppress the growth of black mold and the like on the drum by using ozone water. [Means for solving the problem]

[0007] The present invention 1st A drum-type washing machine according to one aspect includes an outer tub disposed in a housing, a drum disposed in the outer tub and rotatable around a horizontal axis or a rotation axis inclined relative to the horizontal direction, a drive motor for rotating the drum, and an ozone water supply unit for supplying ozone water into the outer tub. a water level sensor for detecting a water level in the outer layer; and a control unit that controls the operation of the drive motor and the ozone water supply unit to perform a tank cleaning operation. Here, the control unit performs a tank cleaning step in the tank cleaning operation, in which the ozone water supply unit stores an amount of ozone water in the outer tank that can contact the drum, and the drive motor rotates the drum to sequentially contact the ozone water with the outer peripheral surface of the drum. Furthermore, during the tank cleaning process, when the water level sensor detects a water level at which the ozone water contacts the outer surface of the drum, the control unit stops the supply of ozone water from the ozone water supply unit to the outer tank.

[0008] According to the above configuration, in the tank cleaning process, the drum rotates, and the outer peripheral surface of the drum is successively brought into contact with the ozone water stored in the outer tank, and the ozone water adheres to the outer peripheral surface of the drum. The disinfecting power of ozone can be applied to the outer peripheral surface of the drum, and biofilm formed on the outer peripheral surface of the drum can be removed.

[0009] A drum-type washing machine according to a second aspect of the present invention comprises an outer tub arranged within a housing, a drum arranged within the outer tub and rotatable around a horizontal axis or a rotation axis inclined relative to the horizontal direction, a drive motor for rotating the drum, an ozone water supply unit for supplying ozone water into the outer tub, and a control unit for controlling the operation of the drive motor and the ozone water supply unit and performing a tub cleaning operation. The control unit controls the ozone water supply unit to store an amount of ozone water in the outer tub such that the outer peripheral surface of the drum comes into contact with the ozone water but the inner peripheral surface of the drum does not come into contact with the ozone water during the tub cleaning operation. The drum is rotated by the driving motor to perform a tank cleaning process in which ozone water is successively brought into contact with the outer peripheral surface of the drum.

[0010] First or second In the drum type washing machine according to the embodiment, the rotation speed of the drum in the tub cleaning step can be set in the range of 20 rpm to 40 rpm.

[0011] According to the above configuration, during the tank cleaning process, it is possible to reliably prevent the ozone water that has reached the outer peripheral surface of the drum from scattering, or even if it does, it is prevented from scattering with enough force to reach the inner surface of the outer tank.

[0012] First or second In the drum-type washing machine according to the embodiment, a drain unit is further provided for draining water from the outer tub. The control unit may be configured to perform a draining step of discharging ozone water from the outer tub by the drain unit after the tub cleaning step, and to perform a dehydration step of rotating the drum to scatter the ozone water remaining in the drum after the draining step.

[0013] According to the above-described configuration, organic matter, bacteria, etc. contained in the ozone water remaining in the drum can be scattered from the drum and discharged from the outer tank.

[0014] First or second In the drum-type washing machine according to the aspect, the control unit may be configured to rotate the drum in one direction in the tub cleaning step.

[0015] According to the above configuration, unlike when the drum is inverted, the ozone water stored in the outer tank is less likely to be strongly agitated, and the ozone is less likely to be gasified, resulting in a decrease in the ozone concentration. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a drum-type washing machine that can effectively suppress the growth of black mold and the like on the drum by using ozone water.

[0017] The effects and significance of the present invention will become more apparent from the following description of the embodiments, however, the following embodiment is merely an example of how the present invention can be implemented, and the present invention is not limited to the following embodiment. [Brief explanation of the drawings]

[0018] [Figure 1]FIG. 1 is a side cross-sectional view showing the configuration of a drum-type washing machine according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing a configuration of a drum type washing machine according to an embodiment. [Figure 3] FIG. 3 is a flowchart showing a control process for the tank cleaning operation according to the embodiment. [Figure 4] 4(a) and 4(b) are flowcharts showing control processes for a first tank cleaning step and a second tank cleaning step, respectively, included in the tank cleaning operation according to the embodiment. [Figure 5] 5(a) and 5(b) are diagrams each showing a schematic diagram of a drum rotating in a first tank cleaning step and a second tank cleaning step according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drum-type washing machine without a drying function, which is one embodiment of the drum-type washing machine of the present invention, will be described below with reference to the drawings.

[0020] FIG. 1 is a side cross-sectional view showing the configuration of a drum-type washing machine 1. As shown in FIG.

[0021] The drum type washing machine 1 has a rectangular housing 10. A circular loading opening 11 through which laundry is loaded is formed in the center of the front surface of the housing 10. The loading opening 11 is covered by a door 12 that can be opened and closed.

[0022] Within the housing 10, an outer tub 20 is elastically supported by a plurality of dampers 21 and springs 22. A drum 23 is rotatably disposed within the outer tub 20. The drum 23 rotates around a horizontal axis. The drum 23 has a circular opening 23a on its front surface, and the outer tub 20 has a circular opening 20a in front of the opening 23a of the drum 23.

[0023] The peripheral edge of the opening 20a of the outer tub 20 and the peripheral edge of the loading port 11 of the housing 10 are connected by an annular packing 24 made of an elastic material. The packing 24 has annular grooves 24a and 24b in its middle and rear end portions. The front end portion of the drum 23 is adjacent to the rear end portion of the packing 24. The peripheral surface of the closed door 12 comes into contact with the packing 24, forming a water seal between the loading port 11 and the door 12.

[0024] A large number of dewatering holes 23b are formed in the inner peripheral surface of drum 23. Burring is applied to each dewatering hole 23b, and the peripheral edge of each dewatering hole 23b protrudes from the outer peripheral surface of drum 23. In addition, an annular balancer 25 is provided at the front of the inner peripheral surface of drum 23, and three baffles 26, each having a substantially triangular prism shape, are provided at equal intervals around the circumference.

[0025] A drive motor 30 is disposed behind the outer tub 20 to generate torque for rotating the drum 23. The drive motor 30 is, for example, an outer rotor DC brushless motor. During the washing and rinsing cycles, the drive motor 30 rotates the drum 23 at a rotation speed at which the centrifugal force acting on the laundry inside the drum 23 is smaller than the force of gravity. On the other hand, during the spin-drying cycle, the drive motor 30 rotates the drum 23 at a rotation speed at which the centrifugal force acting on the laundry inside the drum 23 is much greater than the force of gravity.

[0026] A drain outlet 20b is formed at the bottom of the outer tub 20. A drain valve 41 is provided at the drain outlet 20b. The drain valve 41 includes, for example, a valve and a torque motor that opens and closes the valve. The drain valve 41 is connected to a drain hose 42. The drain valve 41 and the drain hose 42 form a drain unit 40 that drains water from the outer tub 20. When the drain valve 41 is opened, water stored in the outer tub 20 is discharged outside the machine through the drain hose 42.

[0027] A water supply unit 50 for supplying water into the outer tub 20 is disposed at the upper part of the housing 10. The water supply unit 50 includes a first water supply valve 51, a detergent box 52, a water supply hose 53, and a water filling pipe 54. The first water supply valve 51 is disposed at the upper rear part of the housing 10, and the detergent box 52 is disposed at the upper front part of the housing 10. A detergent container 52a containing detergent is accommodated in the detergent box 52 so that it can be freely pulled out from the front. One end of the water supply hose 53 is connected to the first water supply valve 51, and the other end is connected to the detergent box 52. The water filling pipe 54 is connected to the detergent box 52, and the other end is connected to the upper part of the outer tub 20.

[0028] When the first water supply valve 51 is opened, tap water flows from the water faucet through the water supply hose 53, the detergent box 52, and the water supply pipe 54 and is supplied into the outer tub 20. At this time, if detergent is contained in the detergent container 52a, the detergent is pushed by the water and supplied into the outer tub 20.

[0029] An ozone water supply unit 60 for supplying ozone water to the outer tank 20 is disposed in the rear portion of the housing 10. The ozone water supply unit 60 includes a second water supply valve 61, an ozone water generator 62 for generating ozone water, an inlet pipe 63, and an outlet pipe 64. The second water supply valve 61 is disposed in the upper rear portion of the housing 10, and together with the first water supply valve 51, is configured by a dual electromagnetic valve.

[0030] The ozone water generator 62 is disposed above the outer tank 20 and includes a case 65 and an ozone electrode 66. A flow path is formed inside the case 65, and the ozone electrode 66 is disposed within the flow path. The ozone electrode 66 includes a rod-shaped anode, a linear cathode wound spirally around the outer periphery of the anode, and an ion exchange membrane interposed between the anode and the cathode. For example, a diamond electrode is used for the anode, and a platinum electrode is used for the cathode.

[0031] One end of the inlet pipe 63 is connected to the second water supply valve 61, and the other end is connected to the inlet of the case 65. One end of the outlet pipe 64 is connected to the outlet of the case 65, and the other end is connected to the lower part of the outer tank 20.

[0032] When the second water supply valve 61 is opened, tap water from the water faucet flows into the case 65 via the inlet pipe 63 and flows through the flow path. Electricity is applied to the ozone electrode 66, and the water flowing through the flow path is electrolyzed to generate ozone. The generated ozone dissolves in the water, producing ozone water. The ozone water flows out of the case 65 and is supplied into the outer tank 20 via the outlet pipe 64. Note that any ozone that is not dissolved in the water in the case 65 dissolves in the water as it flows through the outlet pipe 64. Ozone water is disinfecting water that has disinfecting properties.

[0033] FIG. 2 is a block diagram showing the configuration of the drum type washing machine 1. As shown in FIG.

[0034] In addition to the above-described configuration, the drum type washing machine 1 includes a control unit 101, a memory unit 102, an operation unit 103, a water level sensor 104, a motor drive unit 105, a water supply drive unit 106, a drain drive unit 107, and an electrode current supply unit 108.

[0035] The operation unit 103 includes a power button for turning the power to the appliance on and off, a start button for starting operation, and a course selection button for selecting an operation course from a plurality of operation courses related to washing operation. The operation unit 103 also includes a tub cleaning button for selecting a tub cleaning operation. The operation unit 103 outputs an input signal to the control unit 101 according to the button operated by the user.

[0036] The water level sensor 104 detects the water level in the outer tub 20 and outputs a water level signal corresponding to the detected water level to the control unit 101.

[0037] The motor driving unit 105 drives the drive motor 30 in accordance with a control signal from the control unit 101. The motor driving unit 105 includes a rotation sensor that detects the rotation speed of the drive motor 30, an inverter circuit, etc., and adjusts the drive power so that the drive motor 30 rotates at the rotation speed set by the control unit 101.

[0038] The water supply driving unit 106 drives the first water supply valve 51 and the second water supply valve 61 in accordance with a control signal from the control unit 101. The drain driving unit 107 drives the drain valve 41 in accordance with a control signal from the control unit 101. The electrode current applying unit 108 applies current to the ozone electrode 66 in accordance with a control signal from the control unit 101.

[0039] The storage unit 102 includes an EEPROM, a RAM, etc. The storage unit 102 stores programs for executing the washing operation and the tub cleaning operation of various operation courses. The storage unit 102 also stores various parameters and various control flags used in executing these programs.

[0040] The control unit 101 controls the motor drive unit 105, the water supply drive unit 106, the drain drive unit 107, the electrode current supply unit 108, etc. in accordance with the program stored in the memory unit 102, based on signals from the operation unit 103, the water level sensor 104, etc. As a result, the control unit 101 controls the operations of the drive motor 30, the drain unit 40, the water supply unit 50, and the ozone water supply unit 60.

[0041] In the drum type washing machine 1, various operation courses are performed based on the user's operation of the operation unit 103. In the washing operation, a washing step, an intermediate spin-drying step, a rinsing step, and a final spin-drying step are performed in order. Depending on the operation course, the intermediate spin-drying step and the rinsing step may be performed two or more times.

[0042] During the washing and rinsing cycles, water is filled in the outer tub 20 up to a predetermined water level. During the washing cycle, detergent is poured into the detergent container 50a, so that the water contained in the outer tub 20 contains detergent. The drive motor 30 alternately rotates forward and backward, causing the drum 23 to alternately rotate forward and backward. At this time, the drum 23 rotates at a rotation speed at which the centrifugal force acting on the laundry inside the drum 23 is smaller than gravity. The laundry inside the drum 23 is lifted up and then dropped by the baffle 26, causing it to slam against the inner circumferential surface of the drum 23. This causes the laundry to be washed or rinsed.

[0043] In the intermediate spin-drying step and the final spin-drying step, drive motor 30 rotates in one direction at high speed, causing drum 23 to rotate at a rotation speed at which the centrifugal force acting on the laundry inside drum 23 is much greater than gravity. The centrifugal force presses the laundry against the inner circumferential surface of drum 23, causing it to be dewatered. In the final spin-drying step, drum 23 rotates at a rotation speed higher than the rotation speed in the intermediate spin-drying step, for example, 600 rpm, for example, 750 rpm.

[0044] In addition to the washing operation, the drum type washing machine 1 also performs a tub cleaning operation to clean the drum 23 and the outer tub 20. The tub cleaning operation will be described in detail below.

[0045] Fig. 3 is a flowchart showing the control process for the tank cleaning operation. Fig. 4(a) and (b) are flowcharts showing the control process for the first tank cleaning step and the second tank cleaning step included in the tank cleaning operation, respectively. Fig. 5(a) and (b) are schematic diagrams showing the state when drum 23 rotates in the first tank cleaning step and the second tank cleaning step, respectively.

[0046] When the tank cleaning operation is selected by the tank cleaning button on the operation unit 103 and then the start button is pressed, the tank cleaning operation starts.

[0047] Referring to FIG. 3, when the tank cleaning operation is started, the control unit 101 first performs a first tank cleaning step (S1).

[0048] 4(a), in the first tank cleaning step, the control unit 101 opens the second water supply valve 61 (S101) and then energizes the ozone electrode 66 (S102). As a result, ozone water having a predetermined concentration, for example, a concentration of approximately 0.4 ppm, is supplied from the ozone water supply unit 60 into the outer tank 20. The drain valve 41 is closed, and the ozone water accumulates in the outer tank 20. The flow rate of the ozone water supplied to the outer tank 20 is, for example, approximately 2 liters / minute.

[0049] The control unit 101 determines whether a first amount of ozone water has been stored in the outer tub 20 (S103). The first amount of water is the amount of water at which the level of the ozone water in the outer tub 20 reaches a level L1, indicated by a dashed line in Fig. 1, at which the ozone water contacts the outer peripheral surface of the drum 23. The first amount of water is, for example, about 8 liters.

[0050] When the water level sensor 104 detects the water level L1, the control unit 101 determines that the first amount of ozonated water has accumulated in the outer tub 20 (S103: YES). Based on this determination, the control unit 101 stops the supply of electricity to the ozone electrode 66 (S104) and then closes the second water supply valve 61 (S105). The supply of ozonated water from the ozonated water supply unit 60 to the outer tub 20 stops. When the first amount of ozonated water, i.e., the water level L1, has accumulated in the outer tub 20, the outer peripheral surface of the drum 23 comes into contact with the ozonated water, but the inner peripheral surface of the drum 23 does not come into contact with the ozonated water.

[0051] Next, the control unit 101 rotates the drive motor 30 to rotate the drum 23 in one direction at the first rotation speed (S106). As the drum 23 rotates, the outer peripheral surface of the drum 23 successively comes into contact with the ozone water stored in the outer tank 20, and the ozone water adheres to the outer peripheral surface.

[0052] Here, the first rotation speed is set to a rotation speed at which the centrifugal force generated when the drum 23 rotates is small, so that the ozone water that has reached the outer peripheral surface of the drum 23 does not scatter, or even if it does scatter, it does not scatter with enough force to reach the inner surface of the outer tank 20. Specifically, the first rotation speed is set to a rotation speed in the range of 20 rpm to 40 rpm. In this embodiment, for example, the first rotation speed is set to 30 rpm.

[0053] Rotating the drum 23 at this first rotation speed makes it easier for the ozone water to remain on the outer peripheral surface of the drum 23, as shown in Fig. 5(a). This allows the sterilizing power of the ozone to act effectively over the entire outer peripheral surface of the drum 23, removing biofilm over the entire outer peripheral surface. In addition, if black mold or the like has developed, it is also killed.

[0054] In addition, the drum 23 rotates in one direction and does not reverse, so the ozone water stored in the outer tank 20 is less likely to be strongly agitated, and the ozone is less likely to be gasified, resulting in a decrease in the ozone concentration.

[0055] When a first time, for example, one minute, has elapsed since the start of rotation of the drum 23 (S107: YES), the control unit 101 stops the drive motor 30, thereby stopping the drum 23 (S108).

[0056] In this way, the first tank cleaning step is completed. In the first tank cleaning step, biofilm, black mold, etc. that have formed on the outer peripheral surface of the drum 23 are mainly removed.

[0057] Returning to FIG. 3, when the first tank cleaning step is completed, the control unit 101 performs a drainage step by operating the drainage unit 40 (S2). That is, the control unit 101 opens the drainage valve 41. Ozone water is discharged from the outer tank 20. The removed biofilm, black mold, etc. are also flushed out from the outer tank 20 together with the ozone water. When the discharge of the ozone water from the outer tank 20 is completed, the drainage step is completed. The drainage valve 41 is kept open.

[0058] Next, the control unit 101 performs the spin-drying process (S3). That is, the control unit 101 rotates the drum 23 at a third rotation speed. The third rotation speed is higher than the second rotation speed, which will be described later, and is also higher than the rotation speed of the drum 23 in the intermediate spin-drying process of the washing operation. For example, the third rotation speed is set to a rotation speed in the range of 650 rpm to 800 rpm. The ozone water remaining in the drum 23 and the organic matter, bacteria, etc. contained therein are scattered from the drum 23 and discharged from the outer tub 20. After a predetermined spin-drying time, for example, four minutes, has elapsed, the control unit 101 stops the drum 23 and closes the drain valve 41. In this way, the spin-drying process ends.

[0059] Next, the control unit 101 performs a second tank cleaning step (S4). Referring to Fig. 4(b), in the second tank cleaning step, the control unit 101 opens the second water supply valve 61 (S201) and then energizes the ozone electrode 66 (S202). As in the first tank cleaning step, ozone water is supplied from the ozone water supply unit 60 into the outer tank 20, and the ozone water accumulates in the outer tank 20.

[0060] The control unit 101 determines whether or not the second amount of ozone water has been stored in the outer tub 20 (S203).

[0061] Here, the inventors conducted experiments on the amount of ozonated water supplied and found that there may be a water volume at which the ozone concentration drops sharply while the ozonated water is being stored in the outer tank 20. This is thought to be due to various factors, such as the passage of time while the ozonated water is being stored, and the increased likelihood of the ozonated water coming into contact with various components such as the drum 23 and door 12 as the ozonated water accumulates, resulting in the loss of ozone due to such contact.

[0062] Therefore, the second water amount is set to a water amount that is less than the water amount that results in the change point and that provides an ozone concentration close to the ozone concentration when the supply of ozone water into the outer tank 20 begins. Furthermore, the second water amount is set to a water amount that is greater than the first water amount. The second water amount is set to, for example, about 15 liters.

[0063] In this embodiment, when a second amount of ozone water is stored in the outer tub 20, the water level in the outer tub 20 becomes a water level L2, shown by the two-dot chain line in Figure 1, at which the ozone water reaches the gasket 24 that seals the door 12 with water.

[0064] When the water level sensor 104 detects the water level L2, the control unit 101 determines that the second amount of ozone water has accumulated in the outer tub 20 (S203: YES). Based on this determination, the control unit 101 stops the power supply to the ozone electrode 66 (S204), and then closes the second water supply valve 61 (S205). The supply of ozone water from the ozone water supply unit 60 to the outer tub 20 stops.

[0065] Next, the control unit 101 rotates the drive motor 30 to rotate the drum 23 in one direction at the second rotation speed (S206). As the drum 23 rotates, the outer peripheral surface of the drum 23 sequentially comes into contact with the ozone water stored in the outer tank 20, and the ozone water adheres to the outer peripheral surface.

[0066] Here, the second rotation speed is set to a rotation speed at which the centrifugal force generated when the drum 23 rotates is large enough to cause the ozone water on the outer peripheral surface of the drum 23 to scatter and come into contact with the inner peripheral surface of the outer tank 20. Specifically, the second rotation speed is set to a rotation speed of 60 rpm or higher. However, if the rotation speed of the drum 23 becomes too high and the ozone water stored in the outer tank 20 is violently struck by the drum 23, the ozone dissolved in the water will gasify, and the ozone concentration will likely decrease. Therefore, to suppress the decrease in the ozone concentration, the second rotation speed is desirably set to a rotation speed in the range of 60 rpm to 120 rpm. In this embodiment, the second rotation speed is set to, for example, 100 rpm.

[0067] As the drum 23 rotates at this second rotation speed, as shown in Figure 5(b), the ozone water is scraped up from the bottom of the outer tub 20, scattered from the outer peripheral surface of the drum 23, and applied to the inner peripheral surface of the outer tub 20, spreading over the entire inner peripheral surface. This allows the sterilizing power of the ozone to act effectively over the entire inner peripheral surface of the outer tub 20, removing biofilm over the entire inner peripheral surface. Furthermore, if black mold or the like has been present, it is also killed.

[0068] Furthermore, as in the first tank cleaning step, the drum 23 rotates in one direction, so that the decrease in ozone concentration can be suppressed.

[0069] Furthermore, since the second amount of ozone water, which is greater than the first amount of water in the first tank cleaning step, is stored in the outer tank 20, even if the water level in the outer tank 20 drops as a result of the ozone water being sprayed onto the inner peripheral surface of the outer tank 20, the water level can be prevented from falling below the outer peripheral surface of the drum 23. This allows the ozone water to be sprayed sufficiently onto the inner peripheral surface of the outer tank 20.

[0070] Furthermore, in the drum-type washing machine 1, biofilms are also likely to form on the surface of the packing 24, particularly in the grooves 24a and 24b. In the second-tub cleaning step, the level of the ozone water in the outer tub 20 reaches the bottom of the packing 24, so that when the drum 23 rotates, the ozone water is likely to reach the entire packing 24, particularly the grooves 24a and 24b. This makes it easier to remove biofilms formed on the packing 24.

[0071] As described above, the outer peripheral surface of the drum 23 is burred so that the peripheral edges of the dewatering holes 23b protrude, and this outer peripheral surface easily scoops up the ozone water stored in the outer tank 20. Therefore, a large amount of ozone water can be scattered from the outer peripheral surface of the drum 23.

[0072] When a second time, for example, two minutes, has elapsed since the start of rotation of the drum 23 (S207: YES), the control unit 101 stops the drive motor 30, thereby stopping the drum 23 (S208).

[0073] Because ozone water is scattered from the drum 23 to wet the inner circumferential surface of the outer tank 20, cleaning the inner circumferential surface of the outer tank 20 takes more time than cleaning the outer circumferential surface of the drum 23. In the second tank cleaning step, the second time is set to be longer than the first time, so that the inner circumferential surface of the outer tank 20 can be prevented from being insufficiently cleaned.

[0074] In this way, the second tank cleaning step is completed. In the second tank cleaning step, biofilm, black mold, etc. that have formed on the inner peripheral surface of the outer tank 20 are mainly removed.

[0075] Returning to Fig. 3, when the second tank cleaning step is completed, the control unit 101 performs the draining step (S5), just as when the first tank cleaning step is completed. Furthermore, when the draining step is completed, the control unit 101 performs the spin-drying step (S6). When the spin-drying step is completed, the tank cleaning operation ends.

[0076] <Effects of the embodiment> According to this embodiment, in the first tank cleaning process, the drum 23 rotates at the first rotation speed, which makes it easier for the ozone water to remain attached to the outer peripheral surface of the drum 23, thereby allowing the disinfecting power of ozone to act effectively on the outer surface of the drum 23, thereby increasing the effectiveness of removing biofilm formed on the outer peripheral surface of the drum 23.

[0077] Furthermore, after the first tank cleaning step is completed, a drainage step is performed, in which the ozone water whose ozone concentration has been significantly reduced due to the consumption of ozone in the first tank cleaning step is discharged from the outer tank 20, and then, in the second tank cleaning step, new ozone water is stored in the outer tank 20. This ensures a sufficient ozone concentration in the second tank cleaning step.

[0078] Furthermore, in the second tank cleaning step, the drum 23 rotates at the second rotation speed, so that the ozone water on the outer peripheral surface of the drum 23 is scattered and comes into contact with the inner peripheral surface of the outer tank 20. This makes it easier for the ozone water to spread over the inner peripheral surface of the outer tank 20, allowing the sterilizing power of ozone to act effectively on the inner peripheral surface of the outer tank 20, thereby enhancing the effect of removing biofilm formed on the inner peripheral surface of the outer tank 20.

[0079] Therefore, according to this embodiment, it is possible to effectively suppress the propagation of black mold and the like in the drum 23 and the outer tub 20.

[0080] Furthermore, according to this embodiment, the first rotation speed is set in the range of 20 rpm to 40 rpm, which ensures that the ozone water on the outer peripheral surface of the drum 23 does not scatter, or even if it does scatter, it does not scatter with enough force to reach the inner peripheral surface of the outer tank 20.

[0081] Furthermore, according to this embodiment, the second rotation speed is set in the range of 60 rpm to 120 rpm. This makes it possible to generate a centrifugal force sufficient to cause the ozone water on the outer peripheral surface of the drum 23 to fly to the inner peripheral surface of the outer tank 20, while also preventing the ozone dissolved in the water from being gasified by the rotating drum 23 violently hitting the ozone water stored in the outer tank 20, thereby preventing a decrease in the ozone concentration. This therefore makes it possible to enhance the effect of removing biofilm formed on the inner peripheral surface of the outer tank 20 by the ozone water.

[0082] Furthermore, according to this embodiment, the amount of ozone water stored in the outer tub 20 by the ozone water supply unit 60 is greater in the second tank cleaning process than in the first tank cleaning process. This prevents the water level in the outer tub 20 from falling below the outer circumferential surface of the drum 23, even if the water level in the outer tub 20 drops as a result of ozone water being sprayed onto the inner circumferential surface of the outer tub 20. This allows a sufficient amount of ozone water to be sprayed onto the inner circumferential surface of the outer tub 20.

[0083] Furthermore, according to this embodiment, after the drainage process and before the second tank cleaning process, a dehydration process is performed in which the drum 23 is rotated at a third rotation speed higher than the second rotation speed. This causes the ozone water remaining in the drum 23 and the organic matter, bacteria, etc. contained therein to fly out of the drum 23 and be discharged from the outer tank 20.

[0084] Furthermore, according to this embodiment, in the first tank cleaning step and the second tank cleaning step, drum 23 rotates in one direction. As a result, unlike when drum 23 rotates in an inverted direction, the ozone water stored in outer tank 20 is less likely to be strongly agitated, and the ozone is less likely to be gasified, resulting in a decrease in the ozone concentration.

[0085] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications to the embodiments of the present invention are possible.

[0086] For example, in the above embodiment, because biofilms are unlikely to form on the inner peripheral surface of drum 23, the first water volume in the first tank cleaning step is set to an amount that prevents the inner peripheral surface of drum 23 from coming into contact with the ozone water, taking into consideration ozone consumption and the like. However, the first water volume may be set to an amount that allows the inner peripheral surface of drum 23 to come into contact with the ozone water. In this case, a cleaning effect on the inner peripheral surface of drum 23 can also be expected.

[0087] Furthermore, in the above embodiment, when the second amount of ozone water is stored in the outer tank 20 in the second tank cleaning step, the water level in the outer tank 20 becomes the water level L2 at which the ozone water reaches the packing 24. However, the water level when the second amount of ozone water is stored in the outer tank 20 may be a water level at which the ozone water does not reach the packing 24.

[0088] Furthermore, in the above embodiment, the amount of ozone water stored in the outer tank 20 by the ozone water supply unit 60 is greater in the second tank cleaning process than in the first tank cleaning process. That is, the second water amount is greater than the first water amount. However, the first water amount and the second water amount may be the same.

[0089] Furthermore, in the above embodiment, in the tank cleaning operation, the spin-drying step is performed after the drainage step after the first tank cleaning step and after the drainage step after the second tank cleaning step. However, the spin-drying step after at least one of the drainage steps may be omitted.

[0090] Furthermore, in the above embodiment, the first tank cleaning step and the second tank cleaning step were each performed once during the tank cleaning operation. However, the first tank cleaning step and the second tank cleaning step may each be performed multiple times. In this case, the first tank cleaning step and the second tank cleaning step may be performed alternately, or the same tank cleaning step may be performed consecutively.

[0091] Furthermore, in the above embodiment, the outlet pipe 64 of the ozone water supply unit 60 may be formed into a serpentine shape using a single pipe or multiple pipes. In this case, the outlet pipe 64 may be arranged along the outer peripheral surface of the outer tank 20. In this configuration, the outlet pipe 64 can be made longer, so that ozone that has not dissolved in water inside the case 65 of the ozone water generation device 62 is more likely to dissolve in water while flowing through the outlet pipe 64.

[0092] Furthermore, in the above embodiment, the drum type washing machine 1 is configured so that the drum 23 rotates around a horizontal axis. However, the drum type washing machine 1 may be configured so that the drum 23 rotates around a rotation axis that is inclined relative to the horizontal direction.

[0093] Furthermore, although the drum type washing machine 1 of the above embodiment does not have a drying function, the present invention can also be applied to a drum type washing machine with a drying function, i.e., a drum type washer-dryer. In addition to the configuration of the drum type washing machine 1 of the above embodiment, the drum type washer-dryer includes a drying unit consisting of a circulation air duct connecting an outlet provided at the bottom of the outer tub 20 with an inlet provided at the top of the outer tub 20, and a fan and heater disposed in the circulation air duct. In this case, the outlet pipe 64 of the ozone water supply unit 60 may be connected to the circulation air duct, and the ozone water may flow through the circulation air duct and be supplied into the outer tub 20 from the outlet.

[0094] 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]

[0095] 10. Cabinet 20 Outer tank 23 Drums 30 Drive motor 40 Drainage section 60 Ozone water supply unit 101 Control section

Claims

1. an outer tank disposed within the housing; a drum disposed in the outer tub and rotatable about a horizontal axis or a rotation axis inclined relative to the horizontal; a drive motor for rotating the drum; an ozone water supply unit that supplies ozone water into the outer tank; a water level sensor for detecting a water level in the outer layer; a control unit that controls the operation of the drive motor and the ozone water supply unit and performs a tank cleaning operation, The control unit, in the tank cleaning operation, a tank cleaning step of storing ozone water in the outer tank by the ozone water supply unit in an amount that can contact the drum, and rotating the drum by the drive motor to sequentially bring the ozone water into contact with the outer peripheral surface of the drum; In the tank cleaning step, when the water level sensor detects a water level at which the ozone water contacts the outer peripheral surface of the drum, the supply of the ozone water from the ozone water supply unit to the outer tank is stopped. A drum type washing machine characterized by the above.

2. An outer tank disposed within a housing; a drum disposed in the outer tub and rotatable about a horizontal axis or a rotation axis inclined relative to the horizontal; a drive motor for rotating the drum; an ozone water supply unit that supplies ozone water into the outer tank; a control unit that controls the operation of the drive motor and the ozone water supply unit and performs a tank cleaning operation, The control unit, in the tank cleaning operation, a tank cleaning step in which the ozone water supply unit stores ozone water in the outer tank in an amount such that the outer peripheral surface of the drum comes into contact with the ozone water but the inner peripheral surface of the drum does not come into contact with the ozone water, and the drum is rotated by the drive motor to sequentially bring the ozone water into contact with the outer peripheral surface of the drum; A drum type washing machine characterized by the above.

3. The drum type washing machine according to claim 1 or 2, The rotation speed of the drum in the tank cleaning step is set in the range of 20 rpm to 40 rpm. A drum type washing machine characterized by the above.

4. The drum type washing machine according to any one of claims 1 to 3, Further provided is a drainage unit for draining water from the outer tank, The control unit After the tank cleaning step, a drainage step is performed in which the drain unit discharges ozone water from the outer tank, After the draining step, a dehydration step is performed in which the drum is rotated to scatter the ozone water remaining in the drum. A drum type washing machine characterized by the above.

5. The drum type washing machine according to any one of claims 1 to 4, The control unit In the tank cleaning step, the drum is rotated in one direction. A drum type washing machine characterized by the above.

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