Drum washing machine

Abstract

To provide a drum type washing machine capable of accurately detecting the generation of detergent bubbles with a simple structure.SOLUTION: A drum type washing machine in the present disclosure includes water level detecting means 46 for detecting the water level in a water tank 33. Control means 57 comprises: a first step of performing supplement water when the water level in the water tank 33 drops to a second predetermined water level lower than a first predetermined water level after reaching the first predetermined water level; and a second step of not performing supplement water even when the water level drops to the second predetermined water level after the first step. In the second step, when the water level drops to a third predetermined water level which is lower than the second predetermined water level, the generation of detergent foam is determined to be a large amount. This allows the generation of the detergent foam to detect accurately.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a drum-type washing machine that agitates clothes and wash water. [Background technology]

[0002] Patent Document 1 discloses a washing machine that detects the generation of detergent foam during washing.

[0003] The drum-type washing machine in Patent Document 1 includes a water tub, a rotating drum rotatably disposed within the water tub, a water supply means for supplying water into the water tub, a water level detection means for detecting the water level in the water tub by pressure, and a drainage means for draining the wash water in the water tub. The control means determines that a large amount of detergent foam is being generated in the water tub when the pressure of the water level detection means due to rotation of the rotating drum is greater than the pressure at a predetermined water level by a predetermined value or more.

[0004] This is because if a large amount of detergent foam is generated during washing due to the use of too much detergent, for example, the foam may adhere to electrical components, causing corrosion or an electrical short circuit, which may lead to malfunctions such as breakdowns. Therefore, it is necessary to quickly detect the generation of large amounts of detergent foam and switch to an operation mode that suppresses foaming.

[0005] Furthermore, if operation is continued while a large amount of detergent foam is being generated, the large amount of detergent foam will create resistance to the rotation of the drum, causing startup problems during the spin-dry operation (abnormal drum rotation), and other problems such as insufficient rinsing and spin-drying performance, or longer operating times. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-68678 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional washing machines described above, if the tub is nearly sealed, when a large amount of detergent foam is generated in the tub, the detergent foam has nowhere to go in the tub and the internal pressure of the tub rises, and the generation of a large amount of detergent foam can be detected by the water level detection means from the change in pressure.However, if the tub is not nearly sealed, the internal pressure of the tub naturally does not rise, and the generation of a large amount of detergent foam cannot be detected.

[0008] That is, if the water supply means or the connection between the detergent inlet and the water tub is not sealed with a valve or the like, it will be open to the atmosphere and it will be impossible to detect the generation of a large amount of detergent foam.

[0009] In addition, if the washing machine is provided with an overflow port for overflowing the wash water in the water tub in addition to the drainage means, the water tub is also exposed to the atmosphere. Furthermore, if the washing machine is provided with a drying means, the drying means generally also has an air intake and exhaust port, which are also exposed to the atmosphere in the same way, making it very difficult to keep the water tub in a nearly sealed state.

[0010] This disclosure , washing The generation of foam restraint A washing machine that can be used is provided. [Means for solving the problem]

[0011] A washing machine according to the present disclosure includes a water tub for storing wash water, a rotating tub rotatably disposed within the water tub, a motor for driving the rotating tub, a water supply means for supplying water into the water tub, a water level detection means for detecting the water level in the water tub, a drainage means for draining water from the water tub, a drain outlet provided at a lower portion of the water tub, a circulation water channel communicating with the drain outlet for circulating the wash water in the water tub to the rotation tub, and a pump for sending the wash water in the water tub to the circulation water channel. A hot air generating means for drying laundry, a hot air blowing path for directing hot air into the water tub, a hot air blowing outlet provided on the rear surface of the water tub for directing the hot air into the water tub, and a foam detecting means including a pair of electrodes provided in the vicinity of the hot air blowing path and in the water tub.and a control means for controlling at least the washing process, the control means being capable of driving the pump during the washing process, and being capable of causing the water supply means to supply make-up water when the water level in the water tub falls to a first predetermined water level after the water supply means has supplied water up to a predetermined water supply level, and being capable of causing the water supply means to supply make-up water when the water level in the water tub falls to a second predetermined water level lower than the first predetermined water level while the pump is being driven, performing a first control for operating the spin tub at a reduced operating rate or operating the spin tub at a reduced rotation speed without draining water using the drainage means, When the resistance value between the pair of electrodes is less than a threshold value, the drainage means drains the wash water in the water tub, and then the water supply means supplies water. When the water level in the water tub falls to the second predetermined water level after the water supply means supplies water again, the first control is not executed. The water level difference between the first predetermined water level and the second predetermined water level is greater than the water level difference between the predetermined feed water level and the first predetermined water level. Effect of the Invention

[0012] The washing machine in this disclosure is , washing The generation of foam restraint can. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a side cross-sectional view of a drum-type washing machine according to a first embodiment. [Diagram 2] A time chart showing the operation of the washing process of the drum washing machine. [Diagram 3] Operation flowchart of the control means of the drum type washing machine [Figure 4] A schematic diagram showing the water level and detergent foam state in the tub of the drum-type washing machine [Diagram 5] Operation flowchart of the control means of the drum type washing machine in the second embodiment [Figure 6] FIG. 11 is a side cross-sectional view of a drum-type washing machine according to a third embodiment. [Figure 7] Operation flowchart of the control means of the drum type washing machine [Figure 8] A schematic diagram showing the water level in the tub of the drum washing machine and the driving state of the pump that circulates the wash water. [Figure 9] FIG. 11 is a side cross-sectional view of a drum-type washing machine according to a fourth embodiment. [Figure 10] Operation flowchart of the control means of the drum type washing machine [Figure 11] A schematic diagram showing the water level and detergent foam state in the tub of the drum-type washing machine DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming more redundant than necessary and to facilitate understanding by those skilled in the art.

[0015] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0016] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to FIGS.

[0017] FIG. 1 is a side cross-sectional view of a drum type washing machine in accordance with a first exemplary embodiment of the present invention.

[0018] As shown in FIG. 1, the water tub 33 is supported by a suspension 41a above the washing machine body 39 and a vibration-isolating member 41b below it so that the water tub 33 can be swung and vibration-proofed. The rotating drum 31 is rotatably provided in the water tub 33, with the central axis of rotation being horizontal from the front side to the back side or tilted downward. The rotating drum 31 is formed in a cylindrical shape with a bottom, and a large number of water holes 32 are provided on the entire outer periphery. A plurality of protrusions 36 for agitating the clothes are provided on the inner wall surface of the rotating drum 31. An opening 38 is provided on the front side of the water tub 33 and the rotating drum 31, and the opening 38 is covered by a lid 37 so as to be freely opened and closed. A user can put laundry in or take it out of the rotating drum 31 through the opening 38 by opening the lid 37. It is possible.

[0019] Water supply valve (water supply means) 44 supplies water into water tub 33 through water supply path 45. Control means 57 is disposed below the main body. One end of drainage path 42 is connected to the bottom of water tub 33, and the other end of drainage path 42 is connected to drain valve (drainage means) 43, which drains the wash water in water tub 33.

[0020] A rotating shaft 34 is provided on the back of rotating drum 31, and a motor 35 attached to the back of water tub 33 is connected to rotating shaft 34. Motor 35 is composed of a DC brushless motor or the like, and is controlled by control means 57 and a drive circuit (not shown) to rotate in forward and reverse directions and to vary the rotation speed, and also detects the load applied to motor 35, i.e., the amount of laundry, based on a signal from a current detection circuit (not shown).

[0021] The control means 57 inputs information from the input setting means 58 for setting the operation course, etc., and displays the information on the display means 59 to inform the user. When the start of operation is set by the input setting means 58, data is input from the water level detection means 46 consisting of the air trap 46a and the pressure sensor 46b to detect the water level in the water tub 33, and the drain valve 43, the water supply valve 44, etc. are operated via the load drive means (not shown). The motor 35 is also controlled via a drive circuit (not shown) to operate a series of processes such as washing, rinsing, and spin-drying.

[0022] The operation and function of the drum type washing machine configured as above when the generation of detergent foam is detected by the water level detection means during washing will be described with reference to Figs. 2 to 4.

[0023] FIG. 2 is a time chart showing the operation of the washing process of the drum type washing machine in embodiment 1 of the present invention, FIG. 3 is an operation flowchart of the control means of the same drum type washing machine, and FIG. 4 is a schematic diagram showing the water level in the tub of the same drum type washing machine and the state of detergent foam (laundry not shown).

[0024] When operation is started (step S100), water supply valve 44 is opened to start supplying water to water tub 33 (step S101), water is supplied until the output of pressure sensor 46b reaches a first predetermined water level (step S102), and when the first predetermined water level is reached, water supply valve 44 is closed (step S103). Next, the first step of the washing process (step S104) is executed.

[0025] In the first process (step S104), the rotating drum 31 is rotated forward and backward to agitate the laundry (for example, the time limit for the motor 35 is "12 seconds on - 1 second off").

[0026] Also in this first process (step S104), the water level in the water tank 33 is constantly detected by the pressure sensor 46b, and it is determined (step S105) whether the water level in the water tank 33 has dropped to a second predetermined water level that is lower than the first predetermined water level (for example, about 20 mm). If the water level has dropped to the second predetermined water level (Yes in step S105), the water supply valve 44 is opened (step S106) to supply water until the water level reaches the first predetermined water level (step S107), and the water supply valve 44 is closed (step S108).

[0027] This is because if the laundry in the rotating drum 31 has low water absorption, i.e., if it is made of a material or knitting style that does not easily get wet, the laundry will gradually absorb the wash water, causing the water level in the water tub 33 to drop. Therefore, water is supplied by the water supply valve 44 to make up for the amount of water absorbed by the laundry, in order to prevent a shortage of wash water during the washing process.

[0028] After that, when a predetermined time (for example, about 2 minutes) has elapsed (step S109), the process proceeds to the next second process (step S110). Since the laundry is agitated by the rotary drum 31 and water is supplied by the water supply valve 44 (steps S106 to S108), the entire laundry is sufficiently wet by the time the first step is completed, even if the laundry has low water absorbency.

[0029] In the second step (step S110), the rotating drum 31 is rotated forward and backward to agitate the laundry (for example, the time limit for the motor 35 is "12 seconds on - 1 second off").

[0030] In the second step (step S110), the water level in water tub 33 is constantly detected by pressure sensor 46b as in the first step, and it is possible to determine whether the water level in water tub 33 has dropped to a second predetermined water level that is lower than the first predetermined water level (for example, about 20 mm). However, in this case, since it is considered that the entire laundry has already been sufficiently wet in the first step, no determination is actually made and water is not supplied by water supply valve 44.

[0031] Furthermore, it is determined whether the water level has dropped to a third predetermined water level (e.g., about 30 mm) lower than the second predetermined water level (step S111). Until the water level drops to the third predetermined water level (No in step S111), the operating rate of the rotating drum 31 is maintained at a high operating rate (step S112). For example, when no detergent foam is being generated, the rotating drum 31 operates "12 seconds on - 1 second off."

[0032] On the other hand, if the water level has dropped to the third predetermined water level (Yes in step S111), it is determined that a large amount of detergent foam has been generated in water tub 33 (step S113).

[0033] Thereafter, the operating rate of the rotating drum 31 is reduced (step S114), thereby suppressing the generation of detergent foam in the water tub 33. For example, when detergent foam is generated, the rotating drum 31 can be operated in a cycle of "5 seconds on-10 seconds off" to suppress the generation of detergent foam.

[0034] Furthermore, even if it is determined in step S113 that a large amount of detergent foam is being generated and the rotating drum 31 is operated at a low operating rate, for example, "5 seconds on-10 seconds off" (step S114), if it is determined again in step S111 by pressure sensor 46b that the water level in the water tub 33 has not dropped to the third specified water level before the specified time has elapsed (step S115), then since the amount of detergent foam being generated in the water tub 33 is not large, the rotating drum 31 may be operated at the original high operating rate, for example, "12 seconds on-1 second off" (step S112).

[0035] In addition, after it is determined in steps S111 and S113 that the amount of detergent foam generation is large, the threshold for determining again in step S111 whether the amount of detergent foam generation is large or not may be a water level (e.g., a second predetermined water level) different from the third predetermined water level. This is to ensure hysteresis because the amount of detergent foam generation in the water tub 33, i.e., the output of the pressure sensor 46b, is highly susceptible to change due to a combination of various factors.

[0036] Here, the water level of the wash water in the water tub 33 and the state of detergent foam generation will be described. Fig. 4(a) is a schematic diagram showing a state in which no detergent foam is generated in the water tub 33 during the washing process and the water level in the water tub 33 indicates Ha as measured by the pressure sensor 46b, while Fig. 4(b) is a schematic diagram showing a state in which detergent foam is generated in the water tub 33 during the washing process and the water level in the water tub 33 indicates Hc as measured by the pressure sensor 46b.

[0037] Furthermore, the generation of detergent foam depends on a variety of factors, including the characteristics of the detergent itself (foaming and defoaming properties), the amount of laundry, the amount of dirt contained in the laundry, water temperature, water quality, and the operating rate of the washing machine's motor 35. Therefore, even if comparing cases where the operating rate of the washing machine's motor 35 and the amount of laundry are constant, the generation of detergent foam is not uniform and will vary due to various other factors. Furthermore, as the washing process progresses, when dirt dissolves from the laundry into the wash water, the detergent components dissolve in the wash water. The detergent foam that is generated generally disappears as it is adsorbed to dirt.

[0038] Here, if detergent foam is not easily generated (for example, when a detergent with low foaming and high defoaming properties is used), the water level Ha in the water tub 33 does not fluctuate significantly even if the washing process progresses once the entire laundry is sufficiently wet. However, if detergent foam is easily generated (for example, when a detergent with high foaming and low defoaming properties is used), the amount of detergent foam in the water tub 33 increases as the washing process progresses, even after the entire laundry is sufficiently wet once, and as a result, the water level Ha in the water tub 33 begins to fluctuate significantly.

[0039] This is because, as shown in Fig. 4(b), part of the wash water in the water tub 33 turns into bubbles and increases in volume, and the apparent water level + foam height rises to Hb, which is higher than Ha, but the actual water level (water surface) itself drops by the amount of the foamed volume, and as a result, drops to Hc, which is lower than Ha (for example, about 50 mm). As a result, even when the entire laundry is sufficiently wet and the water level Ha in the water tub 33 should not drop, the water level in the water tub 33 drops to Hc depending on the generation of detergent foam in the water tub 33, and the degree of this drop can be detected by the degree of detergent foam generation. Note that because pressure sensor 46b detects that part of the wash water turns into bubbles and the water level (water surface) in the water tub 33 drops, this water level (water surface) fluctuation, i.e., the degree of detergent foam generation, can be detected regardless of the airtightness of the water tub 33.

[0040] Thereafter, the washing step proceeds, and after a predetermined time has elapsed (step S115), the step proceeds to the next step (step S116).

[0041] Furthermore, if the detergent foam in the water tub 33 disappears due to a change in condition, such as dirt dissolving from the laundry into the wash water, the water level Hc gradually returns to Ha, and it can be determined from the change in behavior of the pressure sensor 46b that the detergent foam in the water tub 33 has stopped being generated or has disappeared.

[0042] As a result, the generation of detergent foam during washing can be accurately detected, and by quickly suppressing the generation of detergent foam after detecting it, it is possible to prevent detergent foam from adhering to electrical components, etc., causing corrosion or an electrical short circuit, which can lead to malfunctions such as breakdowns.

[0043] It should be noted that lowering the rotation speed of rotating drum 31 is also useful for suppressing the generation of detergent foam in water tub 33. For example, if rotating drum 31 is operated at "45 r / min" when no detergent foam is generated, and if it is determined that there is a large amount of detergent foam, it is operated at "30 r / min", which has the same effect of suppressing the generation of detergent foam as lowering the operating rate of rotating drum 31.

[0044] Furthermore, even if it is once determined that a large amount of detergent foam is being generated and the rotating drum 31 is operated at a low rotation speed, for example, 30 r / min, if the pressure sensor 46b again determines that the water level in the water tub 33 has not dropped to the third specified water level before the specified time has elapsed, then since the detergent foam generation in the water tub 33 is not large, the rotating drum 31 may be operated at the original high rotation speed, for example, 45 r / min.

[0045] (Embodiment 2) 5 is a flowchart showing the operation of a control means of a drum type washing machine in accordance with the second embodiment of the present invention. The same specifications as those in the first embodiment are given the same reference numerals and step numbers, and the description thereof will be omitted.

[0046] If a large amount of detergent foam is generated in the water tank 33, it may adhere to electrical components, causing corrosion or an electrical short circuit, which may lead to malfunctions such as breakdowns. It is necessary to immediately switch to an operation that suppresses foaming. In addition, a more reliable method of suppressing foaming is to drain the wash water in water tub 33 from drainage path 42 using drain valve 43 to the outside of the machine.

[0047] As shown in FIG. 5, in the second process (step S210), it is determined whether the water level has dropped to a third predetermined water level (e.g., about 30 mm) lower than the second predetermined water level (step S211). If the water level has dropped to the third predetermined water level (Yes in step S211), it is determined that a large amount of detergent foam has been generated in the water tub 33 (step S212), and at that stage the wash water in the water tub 33 is quickly drained from the machine via the drain valve 43 through the drain path 42 (step S213).

[0048] In this case, the detergent foam starts to be discharged outside the machine together with the wash water when drainage starts. In other words, since the condition where defects such as corrosion of electrical components or electrical shorts due to detergent foam will no longer occur, it does not matter whether the water is drained to a predetermined water level or for a predetermined time.

[0049] After that, when a predetermined time has elapsed (Yes in step S214), the process proceeds to the next step (step S215).

[0050] (Embodiment 3) Fig. 6 is a side cross-sectional view of a drum type washing machine in embodiment 3 of the present invention, Fig. 7 is an operation flowchart of the control means of the drum type washing machine, and Fig. 8 is a schematic diagram showing the water level in the water tub of the drum type washing machine and the driving state of a pump that circulates the wash water (laundry is not shown). The same specifications as those of embodiment 1 and embodiment 2 are given the same symbols and step numbers, and explanations will be omitted.

[0051] As shown in FIG. 6, the washing machine is provided with a circulation pump 80 connected to the drainage path 42, and a circulation path 81 connected to the circulation pump 80 is connected to a circulation port 82 at the front lower part of the water tub 33, so that the wash water during the washing process is circulated as shown by the arrow a.

[0052] Here, in steps S101 to S103 and the first step (step S104), circulating pump 80 is driven to promote water absorption by the laundry in water tub 33. Since the purpose of the first step (step S104) is to thoroughly wet the entire laundry, the predetermined time (step S109) can be set as short as possible. In other words, the process can be shifted to the second step earlier, and the generation of detergent foam can be detected earlier.

[0053] Generally, the water level in the water tub 33 is lower while the circulation pump 80 is operating than when the circulation pump 80 is not operating, regardless of whether there is detergent foam in the water tub 33. This is because the wash water is forcibly supplied to the laundry by the circulation pump 80, so that the laundry absorbs more wash water than it would naturally absorb, resulting in a decrease in the amount of wash water in the water tub 33.

[0054] On the other hand, laundry located on the rear side of opening 38 of water tub 33 is not only less likely to be splashed with wash water circulated from circulation port 82, but also, as described above, the water level in water tub 33 drops while circulation pump 80 is running, and as a result, the laundry is less likely to come into contact with wash water while circulation pump 80 is running. Therefore, by driving circulation pump 80 intermittently during the washing process, laundry located near opening 38 of water tub 33 can be evenly contacted with wash water while circulation pump 80 is running, and laundry located on the rear side can be evenly contacted with wash water while circulation pump 80 is stopped.

[0055] Here, the fluctuation of the water level (water surface) when detergent foam is generated while the circulation pump 80 is driven and while it is stopped will be described with reference to Fig. 8. As shown in Fig. 8(a), when the circulation pump 80 is driven in a state where the water level in the water tub 33 indicates Hoff while the circulation pump 80 is stopped, The water level in the water tank 33 drops (for example, by about 20 mm) to Hon.

[0056] Next, if detergent foam is generated while the circulation pump 80 is stopped, as described in embodiment 1, the volume of the detergent liquid decreases by the amount that becomes foam, as shown in Figure 8 (b), and the water level drops by ΔHoff (for example, about 50 mm).

[0057] On the other hand, as shown in FIG. 8(c), if detergent foam is generated while the circulation pump 80 is operating, the volume of the detergent liquid also decreases, and the water level drops by ΔHon (for example, about 70 mm) from the water level Hon when there is no detergent foam.

[0058] The reason why "ΔHoff<ΔHon" holds is that water tub 33 and rotating drum 31 are cylindrical, and the surface area S of the water surface is different when circulation pump 80 is running and when it is stopped. That is, when the water level in water tub 33 during washing is below the central axis of rotation, a comparison of the surface area Soff of the water surface at the water level height Hoff when circulation pump 80 is stopped and the surface area Son of the water surface at the water level height Hon when circulation pump 80 is running holds, and therefore "Soff>Son." Also, if the reduction in the volume of the wash water due to the generation of washing foam is the same, then "ΔHoff<ΔHon" holds due to the relationship "Soff>Son."

[0059] Therefore, since the water level fluctuation due to the generation of detergent foam is greater while the circulation pump 80 is operating, that is, the generation of detergent foam can be detected with high sensitivity, it is better to detect the generation of detergent foam using the pressure sensor 46b while the circulation pump 80 is operating (Yes in step S311) (step S312).

[0060] In addition, when the circulation pump 80 is configured with a motor with a variable rotation speed, it is preferable that the rotation speed in the second step (step S310) is constant regardless of the amount of laundry. This is a measure against the following control that is generally performed when the circulation pump 80 with a variable rotation speed is provided. That is, when the amount of laundry is small, that is, the laundry is sufficiently wet even if the amount of circulation by the circulation pump 80 is small, the rotation speed is lowered (for example, about 3000 r / min) to suppress the generation of unnecessary noise and energy consumption, and when the amount of laundry is large, that is, the laundry is not sufficiently wet because the amount of circulation by the circulation pump 80 is not large, the rotation speed is increased (for example, 3500 r / min) to allow the entire laundry to absorb the wash water.

[0061] However, if the rotation speed of the circulation pump 80 is different, the water level Hon while the circulation pump 80 is running will also be different, and the water level ΔHon when detergent foam is generated will also be different. This requires the setting of an appropriate ΔHon for each laundry amount, i.e., the third predetermined water level (step S312), which not only complicates the control but also makes it difficult to accurately detect the generation of detergent foam when the laundry amount is judged to be inconsistent. Therefore, even if the circulation pump 80 is configured with a motor with a variable rotation speed, it is preferable to keep the rotation speed in the second step (step S310) constant regardless of the laundry amount. Since the laundry has already absorbed sufficient water in the first step (step S104), there will be no problems such as a decrease in washing performance.

[0062] If it is determined in step S313 that a large amount of detergent foam has been generated in water tub 33, the operation rate of rotating drum 31 may be reduced as in the first embodiment, or the rotation speed of rotating drum 31 may be reduced. Also, a drainage operation may be performed as in the second embodiment.

[0063] After that, when a predetermined time has elapsed (Yes in step S314), the process proceeds to the next step (step S315).

[0064] (Embodiment 4) FIG. 9 is a side cross-sectional view of a drum type washing machine in embodiment 4 of the present invention, FIG. 10 is an operation flowchart of the control means of the drum type washing machine, and FIG. 11 is a schematic diagram showing the water level in the tub of the drum type washing machine and the state of detergent foam (laundry not shown).

[0065] As shown in FIG. 9, the drying function has a heater 47, a blower fan 48, and a hot air blowing path 49, and has a hot air intake 52 for taking in air from the water tub 33 provided at the front of the top surface of the water tub 33, and a hot air blowing outlet 51 provided at the upper back surface of the water tub 33. Hot air is caused to flow into the water tub 33 and the rotating drum 31 in the direction of arrow b, and the air inside the rotating drum 31 and the water tub 33 is heated and circulated, thereby drying the laundry.

[0066] The foam detection means 70 is composed of a pair of electrodes, namely, a lower electrode 70a disposed near the lower rear surface of the water tub 33 and an upper electrode 70b disposed above the rear surface of the water tub 33 behind the rotating drum 31 or near the hot air outlet 51 in the hot air blowing path 49. The lower electrode 70a is located below the water level of the wash water during a normal washing operation.

[0067] The foam detection means 70 is connected to a resistance value determination circuit (not shown) and detects the resistance between the lower electrode 70a and the upper electrode 70b by comparing it with a reference resistance in the resistance value determination circuit, and if the resistance value is high, it is determined that no foam has entered. When foam enters between the pair of electrodes, a current path is formed by the foam between the lower electrode 70a and the upper electrode 70b, which are submerged in the wash water, and a low resistance value is detected. The resistance value for determination in the resistance value determination circuit is set to less than a threshold value (e.g., 500 kΩ) when foam is present, and to greater than or equal to the threshold value (e.g., 500 kΩ) when no foam is present.

[0068] Here, if detergent foam is generated in the water tub 33, in the second process (step S410), first, the pressure sensor 46b determines whether the water level in the water tub 33 has reached a third predetermined water level (step S411). If the third predetermined water level has not been reached (No in step S411), the process proceeds to step S415. On the other hand, if the third predetermined water level has been reached (Yes in step S411), it is determined that a large amount of detergent foam has been generated (step S412).

[0069] Next, it is determined whether or not the resistance value between the electrodes of the foam detection means 70 is less than 500 kΩ (step S413). If the resistance value between the electrodes of the foam detection means 70 is 500 kΩ or more (No in step S413), the process proceeds to step S415. On the other hand, if it is determined that the resistance value between the electrodes of the foam detection means 70 is less than 500 kΩ (Yes in step S413), it is determined that a larger amount of detergent foam has been generated (step S414). In other words, when comparing the detergent foam height H412 in step S412 with the detergent foam height H414 in step S414, "H412 <H414」となる。

[0070] This is because of the difference in the detection methods and the accuracy. That is, in the detection by the pressure sensor 46b (step S411), the amount of detergent foam to be detected, i.e., the detection threshold value, can be arbitrarily set by the control means 57, whereas in the detection by the foam detection means 70 (step S413), the amount of detergent foam that can be detected is determined only by the physical position of the upper electrode 70b. Also, in the detection by the pressure sensor 46b (step S411), even if a large amount of detergent foam is further generated after the third predetermined water level is reached, that is, even if the water level further drops, it is possible to detect the behavior, whereas in the detection by the foam detection means 70 (step S413), once the lower electrode 70a and the upper electrode 70b are energized by foam, the resistance between the electrodes does not change, so that the behavior cannot be detected even if a large amount of detergent foam is further generated.

[0071] Therefore, if a tolerable amount of detergent foam is generated during the washing process, that is, if the detergent foam adheres to electrical components, it may cause corrosion or electrical shorts, resulting in malfunctions such as breakdowns. When there is still a margin of error up to this point, it is possible to operate the device in a way that prevents any further generation of detergent foam by detecting it with the pressure sensor 46b (step S411). When the detergent foam generation increases further and an unacceptable amount of detergent foam is generated, that is, when the device is in a state just before the above-mentioned malfunction occurs, it is preferable to detect it with the foam detection means 70 (step S413), and thereafter operate the device to quickly remove the detergent foam.

[0072] As described above, when the foam detection means 70 judges that there is a large amount of detergent foam, it is desirable to remove the detergent foam quickly, so an operation is performed to drain the wash water in the water tub 33 using the drain valve 43. In this case, since most of the detergent foam will generally have disappeared after a predetermined time has elapsed, water is again supplied to the water tub 33 using the water supply valve 44, and the wash operation is continued. However, some detergent foam remains even when the water supply starts again, making it difficult to judge whether the third predetermined water level is a state in which a large amount of detergent foam has been generated that should be detected.

[0073] Therefore, in this case, even if the third predetermined water level is reached, it is better not to detect the generation of detergent foam by the pressure sensor 46b.

[0074] (Other embodiments) There are a wide variety of user needs and applications in laundry, such as the types and amounts of laundry, the types and amounts of dirt, and the desired finish of the laundry, and various washing courses exist to meet these needs and applications.

[0075] Some courses include a pre-wash step before the washing step to improve dirt removal and prevent dirt from re-adhering to other laundry. This is done by draining the laundry liquid containing the dirt removed from the laundry from the water tub 33 once after the pre-wash step, in order to prevent the dirt from re-adhering to other laundry.

[0076] In such a course, some detergent foam remains even at the start of the washing step after the pre-washing step, making it difficult to determine whether the third predetermined water level is a state in which a large amount of detergent foam has been generated and should be detected.

[0077] Therefore, in this case, even if the third predetermined water level is reached, it is better not to detect the generation of detergent foam by the pressure sensor 46b.

[0078] In addition, after starting the operation, if there is any laundry that has been forgotten to be put into the rotating drum 31, the washing process can be paused by the input setting means 58 so that the user can add additional laundry to the rotating drum 31 at any time.

[0079] In this case, however, it is difficult to determine whether the change in water level in water tub 33 is caused by the absorption of water by the additional laundry or by the generation of detergent foam.

[0080] Therefore, in this case, even if the third predetermined water level is reached, it is better not to detect the generation of detergent foam by the pressure sensor 46b.

[0081] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0082] As described above, the present invention provides a detergent container that can be used without using a complicated structure in terms of airtightness, etc. It is possible to provide a washing machine that detects the generation of foam. [Explanation of symbols]

[0083] 31 Rotating drum (rotating tank) 33 Aquarium 35 Motor 36 Protrusion 43 Drain valve (drainage means) 44 Water supply valve (water supply means) 46 Water level detection means 46a Air Trap 46b Pressure sensor 57 Control Means 58 Input setting means 59 Display means 70 Bubble detection means 70a Lower electrode 70b Upper electrode 80 Circulation Pump

Claims

1. The washing machine includes a water tub for storing wash water, a rotating tub rotatably disposed within the water tub, a motor for driving the rotating tub, a water supply means for supplying water into the water tub, a water level detection means for detecting the water level within the water tub, a drainage means for draining water from the water tub, a drain outlet provided at the bottom of the water tub, a circulation water channel communicating with the drain outlet and circulating the wash water in the water tub to the rotation tub, a pump for sending the wash water in the water tub to the circulation water channel, a hot air generating means for drying laundry, a hot air blowing path for directing hot air into the water tub, a hot air blowing port provided on the back surface of the water tub for introducing the hot air into the water tub, a foam detection means including a pair of electrodes provided in the vicinity of the hot air blowing path and within the water tub, and a control means for controlling at least the washing process. The control means, in the washing step, The pump is operable, When the water level in the water tank falls to a first predetermined water level after the water supply means has supplied water up to a predetermined water supply level, the water supply means is enabled to supply make-up water; When the water level in the water tank falls to a second predetermined water level lower than the first predetermined water level while the pump is in operation, a first control is executed in which the drainage is not executed by the drainage means, and the rotating tub is operated at a reduced operating rate or at a reduced rotation speed; When the resistance value between the pair of electrodes is less than a threshold value, the drainage means drains the wash water in the water tub, and then the water supply means supplies water. When the water level in the water tub falls to the second predetermined water level after the water supply means supplies water again, the first control is not executed. A drum-type washing machine, wherein a water level difference between the first predetermined water level and the second predetermined water level is greater than a water level difference between the predetermined water supply level and the first predetermined water level.

2. The control means In the washing step, the rotating tank is repeatedly operated in a manner of being turned on for a first time and being turned off for a second time that is shorter than the first time, When the water level in the water tank falls to the second predetermined water level while the pump is being driven, the first control is changed to operate the rotating tank repeatedly in a state in which the rotating tank is turned on for a third time and turned off for a fourth time that is longer than the third time. The drum type washing machine according to claim 1.

3. The control means In the washing step, the rotating tank is operated at a first rotation speed; When the water level in the water tank falls to the second predetermined water level while the pump is being driven, the first control is performed by changing the rotation speed of the rotating tank to a second rotation speed lower than the first rotation speed. The drum type washing machine according to claim 1.

4. the control means, when the water level in the water tank falls to the first predetermined water level while the pump is in operation, does not supply water by the water supply means, and when the water level in the water tank falls to the second predetermined water level, does not drain water by the drainage means and executes the first control. The drum type washing machine according to any one of claims 1 to 3.

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