Washing machine and washing method

Abstract

To provide a washing machine capable of achieving both of suppression of deviation of packing and improvement in detergency.SOLUTION: A washing machine of the present disclosure includes a washing tank, a water supply unit that supplies water into the washing tank, a liquid agent supply unit that supplies a liquid agent into the washing tank, a drive part that rotates the washing tank, and a control part that performs a first step and a second step sequentially. The first step includes at least a water supply step in which the water supply unit supplies water and a stirring step in which the washing tank is rotated and stopped repeatedly. The second step includes at least a liquid agent supply step in which the liquid agent supply unit supplies the liquid agent and a stirring step. The control part controls the water supply unit and the liquid agent supply unit such that the surfactant concentration of the washing water in the stirring step is lower in the first step than in the second step, and the surface tension of the washing water is larger in the first step than in the second step. The control unit controls the drive part such that the total number of rotation of the washing tank in the stirring step is larger in the first step than in the second step.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present disclosure relates to washing machines. [Background technology]

[0002] For example, Patent Document 1 discloses a washing machine that includes a washing tub that can hold laundry, an automatic supply device that automatically supplies liquid to the washing tub, and a control unit that can execute multiple courses.

[0003] The control unit described in Patent Document 1 is capable of executing a first course of standard operation and a second course of operation that is less likely to damage laundry than the first course. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-066062 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when washing an object stuffed with padding or down inside, the washing machine described in Patent Document 1 still has room for improvement in terms of both preventing uneven distribution of the padding and improving cleaning power.

[0006] Therefore, an object of the present disclosure is to solve the above-mentioned problems and to provide a washing machine that can simultaneously suppress uneven stuffing and improve cleaning power. [Means for solving the problem]

[0007] A washing machine according to one embodiment of the present disclosure includes a washing tub, a water supply device that supplies water to the washing tub, a liquid agent supply device that supplies a liquid agent to the washing tub, a drive unit that rotates the washing tub, and a control unit that sequentially executes a first step and a second step, wherein the first step includes at least a water supply step in which the water supply device supplies water and a stirring step in which the washing tub is repeatedly rotated and stopped, and the second step includes at least a liquid agent supply step in which the liquid agent supply device supplies a liquid agent, and a stirring step, and the control unit controls the water supply device and the liquid agent supply device so that the surfactant concentration of the wash water in the stirring step is lower in the first step than in the second step and the surface tension of the wash water is higher in the first step than in the second step, and the control unit controls the drive unit so that the total amount of rotation of the washing tub in the stirring step is greater in the first step than in the second step.

[0008] A washing method according to one embodiment of the present disclosure includes a first step including at least a water supply step in which a water supply device supplies water to a washing tub containing laundry and an agitation step in which a drive unit repeatedly rotates and stops the washing tub; and a second step including at least a liquid supply step in which a liquid supply device supplies liquid to the washing tub after the first step and an agitation step in which the washing tub repeatedly rotates and stops, wherein the surfactant concentration of the washing water in the agitation step is lower in the first step than in the second step, the surface tension of the washing water is higher in the first step than in the second step, and the total amount of rotation of the washing tub in the agitation step is greater in the first step than in the second step. [Effects of the Invention]

[0009] According to the present disclosure, a washing machine can be provided that achieves both suppression of uneven stuffing and improved cleaning power. [Brief explanation of the drawings]

[0010] [Figure 1] Schematic front view of a washing machine according to a first embodiment of the present disclosure. [Figure 2] Schematic cross-section of a washing machine [Figure 3] Perspective view of the automatic insertion unit [Figure 4] Schematic diagram of automatic feeding unit [Figure 5] Graph showing the relationship between surfactant concentration and liquid surface tension [Figure 6] Schematic diagram of a droplet of laundry water being dropped onto the surface of an object [Figure 7] Schematic diagram of a droplet of laundry water being dropped onto the surface of an object [Figure 8] Flowchart of the first cycle of a washing machine [Figure 9] Flowchart of the first washing process [Figure 10] Flowchart of the second washing process [Figure 11] Schematic front view of the washing machine in the first washing process [Figure 12] Schematic front view of the washing machine in the first washing process [Figure 13] Schematic front view of the washing machine in the first washing process [Figure 14] Schematic front view of the washing machine in the second washing process [Figure 15] Schematic front view of the washing machine in the second washing process [Figure 16] Schematic front view of the washing machine in the second washing process [Figure 17] Table comparing the operating conditions for the first and second washing processes [Figure 18] Schematic front view of a washing machine according to a first modification DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment 1) A washing machine 1 according to a first embodiment of the present disclosure will be described.

[0012] Fig. 1 is a schematic front view of a washing machine 1 according to a first embodiment of the present disclosure, and Fig. 2 is a schematic cross-sectional view of the washing machine 1.

[0013] The washing machine 1 according to the first embodiment is a drum-type washing machine with a washing function. The washing machine 1 can execute a normal washing course for clothes such as everyday clothes and underwear. Furthermore, the washing machine 1 can execute a first course, which is a washing course for items with padding inside, such as down coats, down jackets, and down vests, in addition to the normal washing course. The washing machine 1 may also be capable of executing a washing course different from the normal washing course and the first course.

[0014] The washing machine 1 may further have a drying function.

[0015] As shown in FIG. 1, the washing machine 1 includes a housing 2, an outer tub 3, a washing tub 4, a drive unit 5 (FIG. 2), a water supply valve 10, a drain valve 11, a laundry amount detection unit 15 (FIG. 2), a control unit 16, and an operation unit 17.

[0016] The washing machine 1 further includes an automatic dispensing unit 6 and a connecting flow path 8, which supplies a liquid agent to the outer tub 3. The liquid agent is a liquid treatment agent used when treating clothes, towels, sheets, etc. in the washing machine 1.

[0017] The housing 2 is a member that forms the exterior of the washing machine 1. As shown in Fig. 2, an opening 20 and a door 21 that covers the opening 20 and can be opened and closed are provided on the front surface of the housing 2.

[0018] The outer tub 3 is a generally cylindrical member provided inside the housing 2 and functions to store wash water. The outer tub 3 may also be called a water tub or a tub. The outer tub 3 is provided in an opening 31 at a position facing the opening 20 of the housing 2, and the edge of the opening 31 is connected to the opening 20 by a bellows 32. The axis passing through the center of the bottom of the outer tub 3 is defined as a central axis V0. The outer tub 3 is disposed at an angle such that the central axis V0 is at an angle with respect to the horizontal.

[0019] The washing tub 4 is a generally cylindrical member that is rotatable around a central axis V0 inside the outer tub 3 and can accommodate laundry. The washing tub 4 may also be referred to as a washing tub, an inner tub, or a storage tub. The washing tub 4 has a number of through-holes 40 that connect the washing tub 4 to the outer tub 3. The washing tub 4 has an opening 41 at a position facing the opening 20 of the housing 2 and the opening 31 of the outer tub 3. When the user opens the door 21, they can place laundry into the washing tub 4 through the openings 20, 31, and 41.

[0020] Returning to FIG. 1, a plurality of baffles 42 protruding inward toward central axis V0 are provided on the inner peripheral surface of washing tub 4. Baffles 42 extend from the bottom of washing tub 4 toward opening 41 along central axis V0. In the first embodiment, baffles 42 have a triangular cross section when viewed from the front-rear direction (X direction) of washing machine 1.

[0021] 2, the driving unit 5 is a member that drives the washing tub 4 to rotate around the central axis V0. The driving unit 5 has, for example, a motor that rotates the washing tub 4.

[0022] The automatic dispensing unit 6 is a device that automatically supplies a predetermined amount of liquid from a tank that stores enough liquid for multiple uses to the outer tub 3. The predetermined amount of liquid in the automatic dispensing unit 6 is an appropriate amount and type of liquid determined by the control unit 16 in accordance with, for example, the weight of the laundry, the amount of water supplied, or user input.

[0023] The connection flow path 8 connects the automatic dispensing unit 6 to the outer tank 3. Therefore, the liquid agent flows from the automatic dispensing unit 6 into the outer tank 3 through the connection flow path 8. Since the automatic dispensing unit 6 is disposed above the outer tank 3, the connection flow path 8 extends downward.

[0024] The water supply valve 10 has an openable / closable valve connected to a water faucet via an external hose. When the water supply valve 10 is opened, water is supplied to the outer tub 3. Specifically, when the water supply valve 10 is opened, water flows into the outer tub 3 via the automatic dosing unit 6 and the connecting flow path 8.

[0025] Returning to FIG. 1, the water supplied to the outer tub 3 by the water supply valve 10 flows along the inner circumferential surface of the outer tub 3 below the connecting flow path 8 and accumulates in the lower part of the outer tub 3.

[0026] Instead of or in addition to the water supply valve 10, another water supply device for supplying water to the outer tub 3 and the washing tub 4 may be provided.

[0027] Drain valve 11 is a valve that can be opened and closed, and when closed, it stores water in outer tub 3, and when open, it drains the water stored in outer tub 3. Drain valve 11 is provided below outer tub 3. However, instead of drain valve 11, another drain device for draining water from washing tub 4 may be provided.

[0028] 2, laundry amount detection unit 15 has a sensor that detects the amount of laundry contained in washing tub 4. Laundry amount detection unit 15 has, for example, a sensor that measures the weight of the laundry. Specifically, laundry amount detection unit 15 has a sensor that measures the voltage applied to the motor of drive unit 5 and a control circuit that converts the measured voltage into torque applied to drive unit 5 when drive unit 5 rotates and calculates the weight of the laundry based on the torque. Alternatively, laundry amount detection unit 15 may be included in control unit 16.

[0029] Control unit 16 is a controller that controls washing machine 1. Control unit 16 controls components of washing machine 1 such as drive unit 5, automatic dosing unit 6, water supply valve 10, drain valve 11, and operation unit 17. Control unit 16 includes a general-purpose processor such as a CPU, MPU, FPGA, DSP, or ASIC that executes a program to realize predetermined functions. Control unit 16 can realize various controls of washing machine 1 by calling and executing control programs stored in memory unit 16a. Control unit 16 is not limited to a controller that realizes predetermined functions through cooperation between hardware and software, and may be a hardware circuit designed specifically to realize predetermined functions.

[0030] The storage unit 16a is a recording medium that records various information and control programs, and may be a memory that functions as a work area for the control unit 16. The storage unit 16a is realized by, for example, a flash memory, an SSD (Solid State Device), a hard disk, a RAM, other storage devices, or an appropriate combination of these.

[0031] Memory unit 16a stores the operating conditions of the washing course executed by washing machine 1. Specifically, memory unit 16a stores the operating conditions of drive unit 5, operating conditions of automatic dosing unit 6, opening / closing conditions of water supply valve 10, and opening / closing conditions of drain valve 11 for each of the washing process, rinsing process, and spin-drying process of the washing course.

[0032] The memory unit 16a further stores information related to the liquid agent. Specifically, the memory unit 16a stores the type of liquid agent contained in the tank of the automatic dispensing unit 6. For example, the memory unit 16a stores whether the type of liquid agent contained in each tank of the automatic dispensing unit 6 is a detergent, a fabric softener, or a detergent for delicates (i.e., a neutral detergent).

[0033] Operation unit 17 is the part of washing machine 1 that is operated by the user. Operation unit 17 may be configured with one or more buttons, or may be configured with a liquid crystal touch panel. Operation unit 17 includes a start button or a display that functions as a start button. Control unit 16 controls washing machine 1 in response to a user's operation on operation unit 17.

[0034] The user can set information about the washing course to be executed by the washing machine 1 via the operation unit 17. Specifically, the user can set the type of washing course to be executed by the washing machine 1. Furthermore, if the user wants to execute a washing course under operating conditions different from those stored in the memory unit 16a, the user can manually input and set the operating conditions of the washing course.

[0035] Next, a more detailed description will be given of the structure of the automatic feeding unit 6. Fig. 3 is a perspective view of the automatic feeding unit 6. Fig. 4 is a schematic diagram of the automatic feeding unit 6.

[0036] As shown in FIG. 3, the automatic dispensing unit 6 has a case 61, tanks 62A to 62C, pump mechanisms 63A to 63C, a liquid agent discharge flow path 64, and a manual dispensing case 65.

[0037] Case 61 is a container with an open top so as to house three tanks 62A to 62C and manual feeding case 65. Pump mechanisms 63A, 63B, and 63C, a liquid agent discharge flow path 64, and a water supply valve 10 are connected to a rear surface 57 of case 61.

[0038] The tanks 62A to 62C are containers for storing a liquid agent. The tanks 62A to 62C are housed in a state of being lined up on the outer side K1 (the horizontal direction away from the central axis V0 in FIG. 1) of the case 61. The depth and volume of the three tanks 62A to 62C increase on the outer side K1.

[0039] In the first embodiment, taking into consideration the type of liquid and the capacity of tanks 62A to 62C, less frequently used liquid is stored in a tank with a smaller capacity. For example, tank 62C stores detergent, tank 62B stores fabric softener, and tank 62A stores detergent for delicates. Tanks 62A to 62C may also store other types of liquid.

[0040] Tanks 62A to 62C are detachable from case 61 so that the liquid agent can be replenished when the remaining amount becomes low.

[0041] Pump mechanisms 63A, 63B, and 63C are devices that suck out a predetermined amount of liquid from tanks 62A, 62B, and 62C, respectively, and discharge the liquid into liquid discharge flow path 64. As shown in Fig. 4, pump mechanisms 63A, 63B, and 63C are connected to tanks 62A, 62B, and 62C, respectively, in the X direction via rear surface 57 of case 61. Although Fig. 4 shows one tank 62A and one pump mechanism 63A, the other tanks 62B to 62C and pump mechanisms 63B to 63C have similar configurations.

[0042] The pump mechanisms 63A, 63B, and 63C of the present embodiment each include a piston pump. However, the pump mechanisms 63A, 63B, and 63C are not limited to those including a piston pump, and may include, for example, an on-off valve mechanism that discharges liquid by gravity, a gear pump, or the like.

[0043] A liquid agent discharge flow path 64 is connected to the lower portions of the pump mechanisms 63A to 63C. The liquid agent discharge flow path 64 is a flow path member connected to the case 61, and causes water flowing in from the case 61 to merge with the liquid agent discharged from the pump mechanisms 63A to 63C and return the water to the case 61. The case 61 is provided with a flow path below the tanks 62A to 62C that communicates with the liquid agent discharge flow path 64 and through which water and the liquid agent flow.

[0044] The manual dispensing case 65 is a container into which the user manually dispenses one dose of liquid agent each time the washing machine 1 is operated. The manually dispensed liquid agent is supplied to the outer tub 3 in the dispensed amount.

[0045] Next, the flow of water and liquid agent in the automatic dispensing unit 6 will be described.

[0046] As shown in Fig. 3, water supplied from the water supply valve 10 flows into the case 61 from the top of the case 61 and falls toward the bottom of the case 61. The water passes along the bottom of the case 61, below the tanks 62A to 62C, and is supplied to the outer tank 3 (Fig. 2) via the connecting flow path 8.

[0047] A portion of the water supplied from the water supply valve 10 flows from the case 61 into the liquid agent discharge flow path 64. The liquid agent discharged from the pump mechanisms 63A to 63C into the liquid agent discharge flow path 64 joins with the water in the liquid agent discharge flow path 64. The liquid agent and water flow along the slope of the liquid agent discharge flow path 64, flow into the case 61, and are then supplied to the outer tub 3 via the connecting flow path 8. That is, the liquid agent is supplied to the outer tub 3 by the flow of water generated when water is supplied.

[0048] When automatic liquid agent dispensing is not performed, the user may dispense the liquid agent into the manual dispensing case 65. The manually dispensed liquid agent falls toward the bottom of the case 61 together with water supplied from the water supply valve 10, and is supplied to the outer tub 3 together with the water flowing inside the case 61.

[0049] [Operation] As an example of the operation of the washing machine 1 having the above configuration, a first course executed to wash an object having a padding inside will be described.

[0050] The object of the first course has a fabric that forms a space inside and padding that fills the space. The fabric is primarily composed of, for example, polyester or nylon. The padding may be made of any material, such as batting or down. The object of the first course is, for example, a product including a down coat, a down jacket, and a down vest. The object of the first course is not limited to clothing and may be, for example, a futon or a sleeping bag.

[0051] The fabric of the object is water-repellent, so when water gets on the object, the water is repelled by the fabric and does not easily penetrate into the padding.

[0052] On the other hand, wash water is a diluted solution of the liquid agent with water, and contains the liquid agent in addition to water. The liquid agent contains a surfactant that reduces the surface tension of the wash water. Therefore, the wash water has a lower surface tension than pure water.

[0053] In the following description, "surfactant" means a surfactant that reduces the surface tension of a liquid.

[0054] Figure 5 is a graph showing the relationship between surfactant concentration and surface tension of wash water. As shown in Figure 5, as the surfactant concentration increases, the surface tension of wash water decreases. Conversely, as the surfactant concentration decreases, the surface tension of wash water increases.

[0055] For example, decreasing the surfactant concentration from about 500 ppm to about 125 ppm increases the surface tension of the wash water from 31 mN / m to 35 mN / m. Note that the values ​​shown in Figure 5 are exemplary and are not intended to be limiting for certain brands of delicates detergent.

[0056] Here, a predetermined delicates detergent may mean, for example, a detergent in which the amount of surfactant in the concentrate liquid composition is 19-21% or less, which is a lower amount of surfactant than the composition of a typical liquid detergent (22-26% for non-concentrated typical laundry detergents, and approximately 43-55% for concentrated typical laundry detergents).

[0057] The specified detergent for delicates may be, for example, a liquid detergent containing a nonionic surfactant such as polyoxyethylene alkyl ether as an essential component, or may be a liquid detergent containing an anionic surfactant such as a sulfonate or sulfate ester salt in addition to a nonionic surfactant.

[0058] 6 and 7 are schematic diagrams of droplets of wash water dropped onto a target fabric. Wash water W1 in FIG. 6 has a lower surfactant concentration than wash water W2 in FIG.

[0059] As shown in Figure 6, when the surfactant concentration is low and the surface tension is high, droplets of the wash water W1 maintain a large contact angle on the surface of the fabric of the object 18. In other words, the wash water W1 and the surface of the fabric of the object 18 have a low wettability relationship. Therefore, the wash water W1 does not easily penetrate into the fabric of the object 18 and does not easily reach the stuffing. Therefore, when the surfactant concentration is low and the surface tension is high, the stuffing on the object 18 tends to remain dry.

[0060] As shown in Figure 7, when the concentration of surfactant is high and the surface tension is low, the contact angle of the droplets of the wash water W2 is small. In other words, there is a high wettability relationship between the wash water W2 and the fabric surface of the object 18. Therefore, the wash water W2 easily penetrates into the fabric of the object 18 and easily passes through the fabric to reach the stuffing. Therefore, when the concentration of surfactant is high and the surface tension is low, the stuffing in the object 18 is easily wetted.

[0061] Therefore, the inventors conducted an evaluation test to determine the surface tension conditions that make it difficult or easy for the padding of the object 18 to be wetted when using a specified delicate laundry detergent. For the evaluation test, a polyester taffeta test cloth was used, and whether or not a dropped aqueous solution of a surfactant was absorbed was visually determined. Specifically, a paper towel was laid, the test cloth was placed on top of it, and a drop of a diluted aqueous solution of a surfactant at a predetermined concentration was dropped from a height of 10 cm using a plastic dropper. The time from the moment of drop was measured. The time it took for the droplet to pass through the test cloth and be absorbed into the paper towel was visually determined, and this time was measured 10 times. The evaluation test was conducted using an aqueous solution with a surfactant concentration that resulted in a surface tension of 35 mN / m or more, an aqueous solution with a surfactant concentration that resulted in a surface tension of less than 31 mN / m, and an aqueous solution with a surfactant concentration that resulted in a surface tension of 31 mN / m or more but less than 35 mN / m.

[0062] As a result, for aqueous solutions with a surface tension of 35 mN / m or more, it took more than two minutes for the aqueous solution to pass through the test cloth in eight or more of the ten measurements. Furthermore, for aqueous solutions with a surface tension of less than 31 mN / m, the aqueous solution passed through the test cloth within two minutes in all ten measurements. Therefore, the inventors discovered that, under certain conditions, aqueous solutions with a surface tension of 35 mN / m or more have difficulty penetrating an object, whereas aqueous solutions with a surface tension of less than 31 mN / m easily penetrate an object.

[0063] To summarize the above, in order to clean the surface of the object 18 when the stuffing is dry, the surfactant concentration needs to be low and the surface tension needs to be high (for example, 35 mN / m or more). On the other hand, in order to soak the stuffing with washing water and clean the stuffing as well, the surfactant concentration needs to be high and the surface tension needs to be low (for example, less than 31 mN / m).

[0064] The surface tension values ​​given above are merely examples and may be changed depending on other conditions such as the brand of detergent for delicates and the type of surfactant.

[0065] The first course will now be described in more detail with reference to Fig. 8. Fig. 8 is a flowchart of the first course of the washing machine 1.

[0066] In preparation, the user places dirty objects into the washing tub 4.

[0067] Next, the user selects the first course via operation unit 17 as the washing course that the user wishes to execute.

[0068] When the first course is selected, the control unit 16 refers to the storage unit 16a to acquire the operating conditions for the first course.

[0069] The control unit 16 displays a start button on the operation unit 17. When the user presses the start button, the control unit 16 starts the first course.

[0070] As shown in FIG. 8, first, the control unit 16 executes the first washing step (S12).

[0071] Next, the control unit 16 executes the drainage step (S13).

[0072] Subsequently, the control unit 16 executes the second washing step (S14).

[0073] In the first embodiment, each of the washing steps (S12, S14) includes a liquid supply step in which a detergent for delicates is supplied, a water supply step in which water is supplied, and an agitation step in which the washing tub 4 is rotated.

[0074] Therefore, the control unit 16 executes the liquid agent supply step so that the concentration of the delicate detergent in the wash water in the first wash step (i.e., the concentration of the surfactant contained in the delicate detergent) is lower than that in the second wash step. Therefore, the surface tension of the wash water in the first wash step is greater than that in the second wash step. Therefore, the wash water does not easily soak into the object in the first wash step, but it easily soaks into the object in the second wash step.

[0075] Furthermore, the control unit 16 executes the agitation step of the first washing step so that the rotation amount of the washing tub 4 during the agitation step is greater than that during the second washing step. Therefore, in the first washing step, the washing water is agitated more when the washing object has not yet soaked into the washing object, thereby removing dirt adhering to the surface of the fabric. In the second washing step, the washing water is soaked into the washing object, preventing uneven distribution of the stuffing due to agitation, thereby cleaning the washing object.

[0076] Subsequently, the control unit 16 executes the rinsing process (S15). In the rinsing process, water is supplied to the outer tub 3, and the washing tub 4 is rotated to rinse the laundry. In the rinsing process, fabric softener may be supplied to the outer tub 3 together with the water.

[0077] Next, control unit 16 executes the spin-drying process (S16) to finish the first course. In the spin-drying process, drain valve 11 is opened to drain the water in outer tub 3 to the outside, and then drive unit 5 (FIG. 2) rotates washing tub 4 at high speed to spin-dry the laundry.

[0078] In each step, the operation unit 17 displays the step currently in progress. For example, when the washing step (S12, S14) is in progress, the operation unit 17 displays "Washing step", when the rinsing step (S15) is in progress, the operation unit 17 displays "Rinsing step", and when the spinning step (S16) is in progress, the operation unit 17 displays "Spinning step". Note that when the first washing step (S12) is in progress, the operation unit 17 may display "First washing step", and when the second washing step (S14) is in progress, the operation unit 17 may display "Second washing step".

[0079] The first washing step (S12) and the second washing step (S14) will be described in more detail. The operating conditions described below are examples, and the present disclosure is not limited to these.

[0080] Fig. 9 is a flowchart of the first washing step. Fig. 10 is a flowchart of the second washing step. Figs. 11 to 13 are schematic front views of the washing machine 1 in the first washing step. Figs. 14 to 16 are schematic front views of the washing machine 1 in the second washing step.

[0081] As shown in FIGS. 9 and 10, the first and second washing steps each include a liquid supply step for supplying a detergent for delicates, a water supply step, and an agitation step.

[0082] In the first embodiment, the first washing step and the second washing step have different operating conditions. Specifically, the operating conditions for each step are different. However, some of the operating conditions for each step may be common.

[0083] 9 and 11, in the first wash step, the control unit 16 drives the pump mechanism 63A to suck the delicate detergent from the tank 62A and discharge it into the liquid discharge flow path 64 (S21: liquid supply step). Specifically, the control unit 16 determines a first supply amount Q1 of the delicate detergent based on the laundry weight detected by the laundry amount detection unit 15, and operates the pump mechanism 63A for the number of piston strokes or for the pump drive time corresponding to the determined first supply amount Q1.

[0084] In the first embodiment, when washing tub 4 accommodates, for example, 800 g of objects, first supply amount Q1 is, for example, 4 mL. In this case, the surface tension of the wash water is 35 mN / m or more, and may be approximately 45 mN / m.

[0085] 12, the control unit 16 opens the water supply valve 10 and supplies water to the outer tub 3 (S22: water supply step). The control unit 16 continues to supply water until the water level in the outer tub 3 reaches the first water level L11.

[0086] In the water supply step (S22), the control unit 16 determines the first water level L11 so that the surfactant concentration in the wash water in the outer tub 3 is less than a first predetermined value, taking into account the first supply amount Q1 of delicate laundry detergent supplied in the liquid supply step (S21).

[0087] In the first embodiment, the memory unit 16a stores, for each brand of liquid, a first water level L11 at which the concentration of the surfactant becomes less than a first predetermined value according to the first supply amount Q1. Therefore, if the user presets the brand of liquid before starting an operating course, the control unit 16 refers to the memory unit 16a and acquires the first water level L11 according to the brand of liquid and the first supply amount Q1.

[0088] The first water level L11 may be a water level determined by experiment when the washing machine 1 is manufactured.

[0089] Next, as shown in Fig. 13, control unit 16 repeatedly turns drive unit 5 (Fig. 2) ON and OFF to agitate washing tub 4 (S23: agitation step). The agitation step includes multiple alternating rotation steps in which drive unit 5 is turned ON to rotate washing tub 4 and stop steps in which drive unit 5 is turned OFF to stop washing tub 4. The total time of the multiple rotation steps and stop steps is defined as agitation time T10. In the first embodiment, the rotation direction is reversed during successive rotation steps.

[0090] In this specification, "agitation" refers to an operation in which washing tub 4 is repeatedly rotated and stopped. "Agitation" does not include an operation in which washing tub 4 continues to rotate at 300 rpm or more for a long period of time (e.g., 10 minutes or more) without stopping, such as the high-speed rotation of washing tub 4 in the spin-drying process. Note that "agitation" may also include an operation in which washing tub 4 continues to rotate without stopping for several tens of seconds to several minutes.

[0091] By providing a stop step between two rotation steps in the agitation step, it is possible to encourage the object to change its position and spread out, compared to when the object is constantly rotated in the same way. As a result, the washing water can reach parts of the object that have been folded and have not been exposed to the washing water until now.

[0092] The rotation time t1 of one rotation step is shorter than the stop time t2 of one stop step. That is, the time that washing tub 4 is stopped in the agitation step is longer than the time that washing tub 4 is rotating. This operation ensures that the object is immersed in the wash water for a certain period of time, while reducing the mechanical force that the object receives and suppressing damage.

[0093] In the first embodiment, the agitation time T10 is 10 minutes, the rotation time t1 of one rotation step is 5 seconds, and the stop time t2 of one stop step is 22 seconds. The rotation speed of washing tub 4 in the rotation step is 80 rpm.

[0094] Subsequently, the control unit 16 ends the first washing step.

[0095] Returning to FIG. 8, next, control unit 16 executes a draining step (S13). Specifically, control unit 16 opens drain valve 11 to drain the water accumulated in outer tub 3. In the first embodiment, control unit 16 drains the water until the water level in outer tub 3 reaches reference water level L0. As shown in FIG. 14, reference water level L0 is the water level that passes through the lowest end of washing tub 4. On the other hand, after the draining step, the water level in outer tub 3 may be higher or lower than reference water level L0.

[0096] Subsequently, the control unit 16 executes the second washing step (S14).

[0097] 10 and 14, in the second wash step, controller 16 drives pump mechanism 63A to suck the delicate detergent from tank 62A and discharge it into liquid agent discharge flow path 64 (S31: liquid agent supply step). Specifically, controller 16 determines a second supply amount Q2 of delicate detergent based on the laundry weight detected by laundry amount detection unit 15, and operates pump mechanism 63A for the number of piston strokes or pump drive time corresponding to the determined second supply amount Q2.

[0098] The second supply amount Q2 is greater than the first supply amount Q1 in the first washing step. In the first embodiment, when washing tub 4 contains less than 3 kg of objects, second supply amount Q2 is, for example, 36 mL. In this case, the surface tension of the wash water is less than 31 mN / m, and may be approximately 30 mN / m.

[0099] 15, the control unit 16 opens the water supply valve 10 and supplies water to the outer tub 3 (S32: water supply step). The control unit 16 continues to supply water until the water level in the outer tub 3 reaches the second water level L12.

[0100] In the water supply step (S32), the control unit 16 determines the second water level L12 so that the surfactant concentration in the wash water in the outer tub 3 is equal to or greater than the first predetermined value, taking into account the second supply amount Q2 of the delicate laundry detergent supplied in the liquid supply step (S31).

[0101] In the first embodiment, the memory unit 16a stores, for each brand of liquid, a second water level L12 at which the concentration of the surfactant is equal to or greater than the first predetermined value, according to the second supply amount Q2. Therefore, if the user presets the brand of liquid before starting an operating course, the control unit 16 refers to the memory unit 16a and acquires the second water level L12 according to the brand of liquid and the second supply amount Q2.

[0102] The second water level L12 is lower than the first water level L11 in the first washing step.

[0103] Due to differences in the water level and the amount of delicate detergent supplied, the concentration of the delicate detergent in the wash water in the second wash cycle is, for example, 10 times or more higher than that in the first wash cycle during the agitation step after the water supply step. Because the concentration of the delicate detergent and the concentration of the surfactant are proportional, the concentration of the surfactant in the wash water in the second wash cycle is higher than that in the first wash cycle during the agitation step. In other words, the surface tension of the wash water in the second wash cycle is lower than that in the first wash cycle. Therefore, the filling of the object absorbs more wash water in the second wash cycle than in the first wash cycle.

[0104] 16, control unit 16 repeatedly turns drive unit 5 (FIG. 2) ON and OFF to agitate washing tub 4 (S33: agitation step). Similar to the agitation step in the first washing process, the agitation step includes multiple alternating rotation steps in which drive unit 5 is turned ON to rotate washing tub 4 and stop steps in which drive unit 5 is turned OFF to stop washing tub 4. The total time of the multiple rotation steps and stop steps is agitation time T20.

[0105] In the first embodiment, the agitation time T20 is 3 minutes, the rotation time t3 of one rotation step is 3 seconds, and the stop time t4 of one stop step is 24 seconds. The rotation speed of washing tub 4 in the rotation step is 50 rpm.

[0106] Figure 17 is a table comparing the operating conditions for the first and second washing steps. As shown in Figure 17, compared to the first washing step, the agitation time T20 for the second washing step is shorter than the agitation time T10 for the first washing step. The rotation time t3 for one rotation step in the second washing step is shorter than the rotation time t1 for one rotation step in the first washing step.

[0107] The ratio of the rotation times t1 and t3 to the total times t1+t2 and t3+t4 (one rotation step and one stop step) is smaller in the second washing step than in the first washing step. That is, the proportion of the rotation times t1 and t3 in the mixing times T10 and T20 is smaller in the second washing step than in the first washing step.

[0108] Because the agitation time T20 is short, the proportion of rotation time t3 within the agitation time T20 is small, and the rotation speed is also low, the total rotation amount of the washing tub 4 in the agitation step (S33) of the second washing process is smaller than in the agitation step (S23) of the first washing process. The total rotation amount is the sum of the angles through which the washing tub 4 rotates in the agitation step. Depending on the magnitude relationship of the total rotation amount, the mechanical force acting on the object in the agitation step of the second washing process can be made smaller than in the first washing process.

[0109] When the filling is wet, as in the object in the second step, it is heavier than when it is dry. Therefore, when the object is agitated, mechanical forces are applied to the wet filling, causing it to harden and clump together, making it more likely to become unevenly distributed within the object.

[0110] Specifically, the padding is subjected to mechanical force when the object collides with the baffle or the inner surface of washing tub 4, when the object is lifted by baffle 42 and falls from above to hit the liquid surface, and when parts of the object rub against each other. On the other hand, when washing tub 4 rotates at high speed, the object sticks to the inner surface of washing tub 4 and rotates due to centrifugal force, and does not move relative to washing tub 4, so the padding is not subjected to mechanical force.

[0111] Therefore, in the second washing process, the total rotation amount of the washing tub 4 in the stirring step is made smaller than that in the first washing process, thereby reducing the mechanical force acting on the stuffing and preventing the stuffing from being unevenly distributed within the object.

[0112] On the other hand, when the filling is dry, it is relatively light, so mechanical force is less likely to act on it and it is less likely to become unevenly distributed within the object.In the first washing process, because the filling is dry, even if the total rotation amount is increased and mechanical force is applied to the object, the filling does not harden or gather together, so it is less likely to become unevenly distributed within the object.

[0113] Furthermore, in the stirring step (S23) of the first washing process, the first water level L11 in the outer tub 3 is higher than the second water level L12.

[0114] 13, because first water level L11 is high and the surface tension of the wash water is large, object 18 is not easily wetted, and so object 18 floats on the liquid surface at a high position within washing tub 4. When object 18 floats at a high position, object 18 is separated from the inner circumferential surface of washing tub 4, which makes it easier to prevent object 18 from colliding with baffle 42. This further reduces uneven packing.

[0115] 16, in the agitation step (S33) of the second washing process, the liquid level in outer tub 3 is lower than first water level L11, and the surface tension of the wash water is low, so that object 18 absorbs the wash water and is located at the bottom of washing tub 4. Therefore, by weakening the mechanical force in the agitation step (S33) of the second washing process, uneven packing of object 18 can be suppressed.

[0116] In the first embodiment, in the liquid agent supplying steps (S21, S31) and the water supplying steps (S22, S32), the driving unit 5 is OFF and the washing tub 4 is stopped.

[0117] (summary) The above explanations are summarized to describe the features of the present disclosure.

[0118] The washing machine 1 according to the first embodiment can execute a first course including two washing steps to wash the object 18. By differentiating the conditions of the first washing step and the second washing step, it is possible to vary the cleaning effects achieved by each step and prevent uneven filling.

[0119] Specifically, in the first washing step, the control unit 16 controls the automatic dosing unit 6 and the water supply valve 10 to reduce the amount of liquid supplied and increase the water level. As a result, the surface tension of the wash water increases, suppressing absorption of the wash water by the object 18. In the first washing step, the stuffing can be maintained in a dry state, i.e., in a state where it is less likely to become unevenly distributed. In this state, the control unit 16 increases the mechanical force acting on the object 18 while suppressing uneven distribution of the stuffing, thereby removing dirt adhering to the fabric. Furthermore, even while increasing the mechanical force, the water level is increased, which floats the object 18 and reduces collisions with the baffle 42, thereby suppressing the application of excessive mechanical force.

[0120] In the second washing step, the control unit 16 controls the automatic dispensing unit 6 and the water supply valve 10 to increase the amount of liquid supplied and lower the water level. As a result, the surface tension of the wash water is reduced, promoting absorption of the wash water by the objects 18. Because the stuffing is wet and prone to shifting, the control unit 16 reduces the mechanical force compared to the first washing step, thereby preventing the stuffing from shifting.

[0121] [effect] The washing machine 1 according to the first embodiment can achieve the following effects.

[0122] Washing machine 1 of embodiment 1 includes washing tub 4 configured to accommodate laundry, water supply valve 10 (water supply device) that supplies water to washing tub 4, automatic dosing unit 6 (liquid agent supply device) that supplies liquid agent to washing tub 4, drive unit 5 that rotates washing tub 4, and control unit 16. Control unit 16 sequentially executes a first washing process (first process) and a second washing process (second process). The first washing process includes at least a water supply step in which water supply valve 10 supplies water and an agitation step in which washing tub 4 is repeatedly rotated and stopped. The second washing process includes at least a liquid agent supply step in which automatic dosing unit 6 supplies liquid agent and an agitation step in which washing tub 4 is repeatedly rotated and stopped. Control unit 16 controls water supply valve 10 and automatic dosing unit 6 so that the surfactant concentration of the wash water in the agitation step is lower in the first washing process than in the second washing process, and the surface tension of the wash water in the first washing process is higher than in the second washing process. The control unit 16 controls the driving unit 5 so that the total rotation amount of the washing tub 4 in the agitation step is greater in the first washing process than in the second washing process.

[0123] With this configuration, in the first washing step, the surface tension of the wash water is reduced, making it difficult for the wash water to penetrate into the stuffing of the object. By increasing the mechanical force when the stuffing is dry, it is possible to remove dirt adhering to the outside of the object while preventing unevenness of the stuffing. In the second washing step, the surface tension is increased, making it easier for the wash water to penetrate into the stuffing of the object. By reducing the mechanical force when the stuffing is wet, it is possible to clean the stuffing while preventing unevenness of the stuffing.

[0124] In the washing machine 1 of the first embodiment, the water level in the washing tub 4 in the agitation step is higher in the first washing cycle than in the second washing cycle.

[0125] With this configuration, by raising the water level in the first washing process, it is possible to prevent the object from hitting the baffle 42 and further prevent uneven packing. On the other hand, in the second washing process, the mechanical force is small, so uneven packing is less likely to occur even if the water level is lowered. Lowering the water level makes it easier to increase the concentration of surfactant.

[0126] In the washing machine 1 of embodiment 1, the first washing process and the second washing process each include a liquid agent supply step in which the automatic dispenser unit 6 supplies liquid agent, and the amount of liquid agent supplied in the liquid agent supply step is less in the first washing process than in the second washing process.

[0127] With this configuration, the concentration of the surfactant in the first washing step can be made lower than that in the second washing step.

[0128] In the washing machine 1 of the first embodiment, the concentration of the liquid agent in the wash water in the agitation step is 1 / 10 or less in the first washing step compared to the second washing step.

[0129] With this configuration, the concentration of the surfactant in the first washing step can be made lower than that in the second washing step.

[0130] In the washing machine 1 of the first embodiment, the agitation time of the agitation step is longer in the first washing cycle than in the second washing cycle.

[0131] With this configuration, it is easier to make the mechanical force acting on the object in the first washing step greater than that in the second washing step.

[0132] In washing machine 1 of embodiment 1, the agitation step includes a plurality of rotation steps in which washing tub 4 rotates and a plurality of stop steps in which washing tub 4 stops. The rotation time of one rotation step is longer in the first washing step than in the second washing step.

[0133] This configuration increases the rotation angle in each rotation step in the first washing process, which increases the number of times the object is lifted and slammed onto the surface of the wash water in each rotation step, improving the cleaning effect.

[0134] In washing machine 1 of the first embodiment, in the agitation step, the times t2 and t4 during which washing tub 4 is stopped are longer than the times t1 and t3 during which washing tub 4 is rotated.

[0135] With this configuration, compared to when the stop times t2 and t4 are shorter than the rotation times t1 and t3, the mechanical force is weakened to reduce damage to the object, while the time the object is immersed in the wash water is ensured, thereby improving the cleaning effect.

[0136] The washing machine 1 of the first embodiment further includes a drain valve 11 for draining water from the washing tub. The control unit 16 opens the drain valve 11 between the first washing step and the second washing step.

[0137] With this configuration, by discharging at least a portion of the wash water supplied in the first washing step, it becomes easier to increase the surfactant concentration of the wash water in the second washing step.

[0138] In the washing machine 1 of the first embodiment, the first washing process and the second washing process each include a water supply step in which the water supply valve 10 supplies water, a liquid agent supply step in which the automatic dosing unit 6 supplies liquid agent, and a stirring step.

[0139] This configuration prevents soil that has been lifted from the clothes from reattaching to the clothes, improving the cleaning effect of the first washing process compared to when the first washing process does not include a liquid supply step. Also, compared to when the second washing process does not include a water supply step and the wash water from the first washing process is also used in the second washing process, the risk of recontamination can be reduced.

[0140] The present disclosure is not limited to the first embodiment, but can be embodied in various other forms.

[0141] In the first embodiment, the central axis V0 of the outer tub 3 is inclined at an angle relative to the horizontal, but this is not limiting. For example, the washing machine 1 may be a vertical washing machine, and the central axis V0 of the outer tub 3 may extend vertically. In this case, the rotation direction of the washing tub 4 does not need to be reversed during the agitation steps of the first and second washing steps.

[0142] In the first embodiment, the liquid agent is supplied by the automatic dispensing unit 6 in the first washing step and the second washing step, but the present invention is not limited to this. As in Modification 1 described below, when the washing machine 1 includes a manual dispensing case 165 separate from the manual dispensing case 65, the liquid agent may be supplied manually.

[0143] Although the example in which the automatic dosing unit 6 supplies a liquid treatment agent to the outer tub 3 has been described, the present invention is not limited to this. For example, the automatic dosing unit 6 may supply a powdered treatment agent or a solid treatment agent such as a tablet to the outer tub 3. The automatic dosing unit 6 may also directly eject the treatment agent into the outer tub 3. In this case, the water supply step may be omitted from the second washing process.

[0144] In the first embodiment, the laundry amount detection unit 15 detects the weight of the laundry, but the present invention is not limited to this. For example, the laundry amount detection unit 15 may detect other physical quantities that indicate the amount of laundry, such as the volume of the laundry.

[0145] In the first embodiment, an example in which operation unit 17 is provided in washing machine 1 has been described, but the present invention is not limited to this. Operation unit 17 may be provided in a device separate from washing machine 1. For example, an application stored in a user's smartphone may function as operation unit 17. Specifically, washing machine 1 may have a communication unit, and the communication unit of washing machine 1 may communicate with the smartphone, and operation unit 17 such as a start button may be displayed on the display of the smartphone.

[0146] In the first embodiment, an example in which the first washing step includes a liquid agent supplying step has been described, but the present invention is not limited to this. The first washing step does not have to include a liquid agent supplying step. That is, the object may be washed using water in the first washing step.

[0147] In the first embodiment, the control unit 16 drains the wash water between the first and second washing steps, but this is not limiting. The control unit 16 may keep the drain valve 11 closed between the first and second washing steps, and not drain the water. In this case, the liquid agent introduced into the outer tub 3 in the first washing step can also be used in the second washing step. Draining the water reduces the amount of liquid agent supplied in the second washing step, reducing the number of times the user needs to refill the tank 62A, improving the convenience of the washing machine 1.

[0148] (Variation 1) Fig. 18 is a schematic front view of washing machine 101 according to Modification 1. As shown in Fig. 18, washing machine 101 differs from washing machine 1 according to Embodiment 1 in that washing machine 101 includes manual loading case 165 separate from manual loading case 65 and water supply valve 110 separate from water supply valve 10.

[0149] Manual dispensing case 165 may have a similar configuration to manual dispensing case 65, and is a container into which a user manually dispenses a single dose of liquid agent each time the washing machine 1 is operated. A powder processing agent may be dispensed into manual dispensing cases 65, 165 instead of a liquid agent.

[0150] The water supply valve 110 is connected to a water faucet and has a valve that can be controlled to open and close independently of the water supply valve 110. The water supply valve 110 introduces water into the manual input case 165.

[0151] When one of the water supply valves 10, 110 is opened, the liquid in the corresponding case is supplied to the outer tank 3 at once (i.e., in one step).

[0152] When the water supply valve 10 is opened, water is supplied to the manual input case 65 and the liquid agent in the manual input case 65 is supplied to the outer tub 3, but water is not supplied to the manual input case 165. On the other hand, when the water supply valve 110 is opened, water is supplied to the manual input case 165 and the liquid agent in the manual input case 165 is supplied to the outer tub 3, but water is not supplied to the manual input case 65. In other words, the two manual input cases 65, 165 have independent water supply paths.

[0153] Therefore, the liquid agent in the manual input cases 65, 165 can be supplied to the outer tub 3 at different times (different steps). For example, by manually inputting the liquid agent into each of the manual input cases 65, 165, and opening the water supply valve 10 in the first washing step and the water supply valve 110 in the second washing step, the liquid agent in the manual input case 65 can be supplied to the outer tub 3 in the first washing step and the liquid agent in the manual input case 165 in the second washing step.

[0154] Alternatively, the liquid agent may not be dispensed into the manual dispenser case 65, but may be dispensed automatically in the first washing step.

[0155] Furthermore, the liquid agent may not be put into the manual input case 65, and water washing may be performed in the first washing step by opening the water supply valve 10 in the first washing step.

[0156] Alternatively, the water supply valve 110 may be opened in the first washing step, and the water supply valve 10 may be opened in the second washing step.

[0157] When detergent is put into manual dispenser case 65, fabric softener may be put into manual dispenser case 165.

[0158] A washing machine in a first aspect includes a washing tub configured to accommodate laundry, a water supply device that supplies water to the washing tub, a liquid agent supply device that supplies a liquid agent to the washing tub, a drive unit that rotates the washing tub, and a control unit that sequentially executes a first step and a second step, wherein the first step includes at least a water supply step in which the water supply device supplies water and a stirring step in which the washing tub is repeatedly rotated and stopped, and the second step includes at least a liquid agent supply step in which the liquid agent supply device supplies a liquid agent and a stirring step in which the washing tub is repeatedly rotated and stopped, and the control unit controls the water supply device and the liquid agent supply device so that the surfactant concentration of the wash water in the stirring step is lower in the first step than in the second step and the surface tension of the wash water is higher in the first step than in the second step, and the control unit controls the drive unit so that the total amount of rotation of the washing tub in the stirring step is greater in the first step than in the second step.

[0159] In the washing machine of the second aspect, in the washing machine of the first aspect, the water level in the washing tub in the agitation step is higher in the first step than in the second step.

[0160] As a washing machine in a third aspect, in the washing machine in the second aspect, the first step and the second step each include a liquid agent supplying step in which a liquid agent supplying device supplies a liquid agent, and the amount of liquid agent supplied in the liquid agent supplying step is less in the first step than in the second step.

[0161] In a fourth aspect of the washing machine, in the washing machine of the third aspect, the concentration of the liquid agent in the wash water in the stirring step is 1 / 10 or less in the first step compared to the second step.

[0162] As a washing machine according to a fifth aspect, in the washing machine according to any one of the second to fourth aspects, the agitation time in the agitation step is longer in the first step than in the second step.

[0163] As a washing machine in a sixth aspect, in the washing machine in any one of the first to fifth aspects, the stirring step includes a plurality of rotation steps in which the washing tub rotates and a plurality of stop steps in which the washing tub stops, and the rotation time of one rotation step is longer in the first step than in the second step.

[0164] In a seventh aspect of the washing machine, in the washing machine of any one of the first to sixth aspects, the time during which the washing tub is stopped is longer than the time during which the washing tub is rotated in the agitation step.

[0165] In an eighth aspect, the washing machine is a washing machine according to any one of the first to seventh aspects, further comprising a drain valve for draining water from the washing tub, and the control unit opens the drain valve between the first step and the second step.

[0166] As a washing machine in a ninth aspect, in the washing machine in any one of the first to eighth aspects, the first step and the second step each include a water supply step in which a water supply device supplies water, a liquid agent supply step in which a liquid agent supply device supplies liquid agent, and the stirring step.

[0167] A washing method in a tenth aspect includes a first step including at least a water supply step in which a water supply device supplies water to a washing tub containing laundry and a stirring step in which a drive unit repeatedly rotates and stops the washing tub; and a second step including at least a liquid supply step in which a liquid supply device supplies liquid to the washing tub after the first step and a stirring step in which the washing tub repeatedly rotates and stops, wherein the surfactant concentration of the washing water in the stirring step is lower in the first step than in the second step, the surface tension of the washing water is higher in the first step than in the second step, and the total amount of rotation of the washing tub in the stirring step is greater in the first step than in the second step.

[0168] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art, and such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. [Industrial Applicability]

[0169] The washing machine of the present disclosure is capable of washing objects and is therefore useful as a domestic washing machine, a commercial washing machine, or any type of washer / dryer (for example, a domestic drum washing machine or a top-loading washing machine). [Explanation of symbols]

[0170] 1 washing machine 2. Case 3 Outer tank 4 Washing machine 5 Drive unit 6 Automatic feeding unit 10. Water supply valve 11 Drain valve 15 Cloth amount detection unit 16 Control Unit 17 Control section 61 cases 62A~62C Tank 63A~63C Pump mechanism

Claims

1. A washing tub configured to be able to accommodate laundry; a water supply device that supplies water to the washing tub; a liquid agent supplying device for supplying a liquid agent to the washing tub; A drive unit that rotates the washing tub; a control unit that sequentially executes the first step and the second step, The first step includes at least a water supply step in which the water supply device supplies water, and an agitation step in which the washing tub is repeatedly rotated and stopped, The second step includes at least a liquid agent supplying step in which the liquid agent supplying device supplies the liquid agent, and a stirring step in which the washing tub is repeatedly rotated and stopped, the control unit controls the water supply device and the liquid agent supply device so that a surfactant concentration of the wash water in the agitation step is lower in the first step than in the second step, and a surface tension of the wash water in the first step is higher than in the second step, The control unit controls the drive unit so that a total rotation amount of the washing tub in the agitating step is greater in the first step than in the second step.

2. The washing machine according to claim 1 , wherein the water level in the washing tub in the agitating step is higher in the first step than in the second step.

3. each of the first step and the second step includes a liquid agent supplying step in which the liquid agent supplying device supplies a liquid agent; The washing machine according to claim 2 , wherein the amount of the liquid agent supplied in the liquid agent supplying step is smaller in the first step than in the second step.

4. The washing machine according to claim 3, wherein the concentration of the liquid agent in the washing water in the stirring step is 1 / 10 or less in the first step compared to the second step.

5. The washing machine according to claim 2 , wherein the agitation time of the agitation step is longer in the first step than in the second step.

6. The stirring step includes a plurality of rotation steps in which the washing tub rotates and a plurality of stop steps in which the washing tub stops, The washing machine according to claim 1 , wherein the rotation time of one rotation step is longer in the first step than in the second step.

7. The washing machine according to claim 1 , wherein in the stirring step, the time during which the washing tub is stopped is longer than the time during which the washing tub is rotated.

8. Further provided is a drain valve for draining water from the washing tub, The washing machine according to claim 1 , wherein the control unit opens the drain valve between the first step and the second step.

9. 9. The washing machine according to claim 1, wherein the first step and the second step each include a water supplying step in which the water supply device supplies water, a liquid agent supplying step in which the liquid agent supplying device supplies the liquid agent, and the stirring step.

10. A first process includes at least a water supply step in which a water supply device supplies water to a washing tub containing laundry, and a stirring step in which a drive unit repeatedly rotates and stops the washing tub; a second step including at least a liquid agent supplying step in which a liquid agent supplying device supplies the liquid agent to the washing tub after the first step, and an agitating step in which the washing tub is repeatedly rotated and stopped, The surfactant concentration of the wash water in the stirring step is lower in the first step than in the second step, and the surface tension of the wash water is higher in the first step than in the second step, A washing method, wherein the total rotation amount of the washing tub in the agitation step is greater in the first step than in the second step.

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