JP2005087466A - Drum type washing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent noise or excessive detergent bubbles from getting generated by the lowering of a water level in a water tank with the circulation of washing water by a circulating pump and the entry of the bubbles in the circulating pump as well. <P>SOLUTION: The washing machine circulates washing water by rotating a drum 5 and driving the circulating pump 14, and pours the washing water onto the wash during a washing action. Even if the water level in the water tank 2 lowers due to the circulation of the washing water, the circulating flow rate of the circulating pump 14 is controlled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a drum-type washing machine that includes a drum that rotates around a horizontal axis and has improved cleaning performance.

  The drum-type washing machine includes a drum that is rotatable around a so-called horizontal axis around a horizontal axis or an inclined axis in a water tub, and performs a process from washing as a washing operation to dehydration and further drying as necessary. The drum storing the drum is rotated and driven, and the washing operation and the rinsing operation are characterized in that the washing is lifted and dropped while the drum is rotated at a low speed. According to such a cleaning means, the amount of water that is wet enough to be washed whenever the laundry falls is sufficient as the washing water, and a large mechanical force such as friction does not act on the laundry. It has a cleansing effect and is rapidly spreading to general households. However, on the other hand, there are some disadvantages, for example, it takes a long time to clean stubborn dirt.

Therefore, in recent years, various studies have been made to further improve the washing performance of this type of drum type washing machine. For example, in the washing process, in addition to the above-described tapping operation, the drum is washed to the extent that the washing water contained in the laundry is squeezed out. So that the so-called squeezing washing operation is added, or a circulation pump is provided in communication with the upper and lower parts of the water tank in which the drum is installed, and the circulation pump is directed to the laundry in the drum during the washing process. Thus, a washing means has been devised that actively promotes water-containing action by actively pouring washing water, thereby improving washing performance as tapping (see, for example, Patent Document 1).
JP-A-8-299658 (pages 5 and 7 and FIGS. 4 and 14)

  The problem we are trying to solve is that if the water content of the laundry is increased by the circulation pump, the amount of water stored in the aquarium will be further reduced and the water level will be lowered. Then, air is sucked into the circulation pump. In such a case, there is a problem that the noise of the circulation pump increases due to the mixed bubbles and excessive detergent bubbles are generated. In particular, this excessive foaming not only causes rotation resistance of the drum, but it is difficult to quickly discharge from the drum or the water tank, and also causes problems such as leakage outside the water tank through a portion communicating with the outside air, and it is naturally easy to wash. There is a problem that the cleaning effect is too bad.

  In order to solve the above-mentioned problems, the present invention provides a drum type washing machine capable of maintaining a water level that does not suck air by controlling the flow rate of the circulation pump even when the water level drops due to the circulation of washing water. For the purpose.

  In order to achieve the above object, the drum type washing machine of the present invention is provided with a drum that rotates around a horizontal axis in a water tank, and a circulating water channel that is communicated with the upper and lower parts of the water tank via a water outlet and a water inlet. In addition to providing a circulation pump in the middle of the circulation channel, the drum is rotated during the washing operation, and the circulation pump is driven to circulate the washing water, and the water absorption is performed during the washing water circulation. The main feature is that the circulation flow rate by the circulation pump is controlled in order to maintain the water level at which no air is sucked from the mouth.

  According to the drum-type washing machine of the present invention, for the laundry subjected to the washing operation which is a washing operation, water is injected while circulating the washing water, thereby promoting the water-containing action and improving the washing performance. Since the flow rate of the pump is controlled to a water level that does not suck air from the water inlet of the circulation water channel, bubbles are mixed into the pump, which is effective for generating a loud noise and suppressing the generation of detergent bubbles.

(First embodiment)
First, a description will be given with reference to FIGS. 1 to 3 showing a first embodiment of the present invention.
The longitudinal cross-sectional view of FIG. 1 shows a schematic configuration of a drum washing machine with a drying function, for example, and a water tank 2 having a horizontal cylindrical shape is appropriately elasticated inside a casing 1 that forms an outer shell. Elastic support is provided via the support device 3. This water tank 2 has a substantially non-porous shape and can store water, and can be drained to the outside via a drain valve 4 at the bottom, and the front side is greatly opened. The water tank 2 is provided with a cylindrical drum 5 that can rotate around the horizontal axis, specifically around the tilt axis. The drum 5 has a large number of through holes 5a on the peripheral wall. In the same manner as the above, the front side is greatly opened, and is rotated by a motor 7 attached and fixed to the back of the water tank 2 via a drum shaft 6 that rotatably supports the front side.

  Opposing to the front opening of the drum 5 and the water tub 2, an input port 8 for taking in and out laundry (not shown) is formed on the front surface of the housing 1. A door 9 for opening and closing is attached to be rotatable. However, a flexible bellows that seals between the front opening of the aquarium 2 and the inlet 8 so that washing water stored in the aquarium 2 or splashed water splashes do not leak out of the aquarium 2. 10, when the door 9 is in a closed state, it contacts the back side of the door 9 to prevent leakage of water from the charging port 8 to the outside of the machine.

  In this embodiment, a hot air supply means 11 and a heat exchanger 12 as a drying function are provided, and the hot air supply means 11 and the heat exchanger 12 are connected to the upper and lower portions of the water tank 2 and a circulation duct 13. It is formed in the middle part of. Specifically, the heat exchanger 12, the blower fan mechanism 11 a as the hot air supply means 11, and the heater device 11 b are sequentially arranged from the upstream side in the path of the circulation duct 13. On the other hand, the heat exchanger 12 has a configuration utilizing a dehumidifying function by water cooling inside, and cools warm air containing so-called moisture so that moisture can be condensed and discharged. Air can be efficiently heated and warmed by the heater device 11 b and supplied to the water tank 2 and the drum 5 through the circulation duct 13.

  A circulation pump 14 is provided at the inner bottom of the housing 1. The circulation pump 14 has a water suction pipe 15 having its water suction port 15 a communicating with the lower part of the water tank 2, and a discharge port 16 a extending to the upper front of the water tank 2 and provided at a position facing the inside from the front opening of the drum 5. Although the details of the function will be described later, it is driven in conjunction with the washing operation of the washing process, and the washing water is so-called via the water absorption line 15 and the discharge line 16 as indicated by arrows in the figure. While circulating, washing water (detergent solution) can be poured toward the laundry (not shown) in the drum 5. Note that the opening position of the water suction port 15a is formed in communication with the lower part of the corresponding water tank 2 so that a lower limit water level effective for the tapping operation can be secured in the drum 5.

  By the way, a tube 17 is connected to the lower part in the water tank 2 and a pressure sensor 18 is provided at the upper end thereof, which functions as a water level detection means for detecting the washing water level in the water tank 2. In particular, in this embodiment, in addition to detecting the constant water level A necessary for the original washing process, the water level just above the water intake port 15a of the circulation pump 14, that is, the low water level B which is also the lower limit of the water level exhibiting a so-called normal pump function. The first threshold value for detecting the water level and the second threshold value for detecting the return water level C when the water level recovers and does not reach the constant water level A but can perform a sufficient pumping function and are re-driven. Based on the detection result, the circulation pump 14 is operated to be turned on and off based on a control device (not shown) to control the operation, thereby enabling the circulation flow rate to be controlled.

  On the other hand, the heat exchanger 12 is provided with another pressure sensor 20 through a similar tube 19. This pressure sensor 20 can detect pressure fluctuations with higher accuracy than the pressure sensor 18 of the water level detection means described above. The pressure sensor 20 detects a pressure fluctuation based on a large amount of detergent bubbles generated in the water tank 2 and eventually entering the heat exchanger 12, and functions as a so-called foam detection means. Although details will be described later, for example, when foaming is detected, operation control such as turning off the circulation pump 14 by a control device is possible.

In FIG. 1, 21 is a water supply valve, one of the two branches is connected to the upper part of the water tank 2 via a water supply line 22 and functions as a water supply means for supplying washing water, and the other is a water supply line. It is connected to the upper part of the heat exchanger 12 through 23 and can be supplied as cold water for water cooling means.
FIG. 2 is a time chart showing the main part at the beginning of the washing process, in particular, showing the operation status of the circulation pump 14 according to the fluctuation of the water level. Further, FIG. 3 shows the amount of cloth and the pump flow rate according to the cloth quality of the laundry. These will be described in detail in the following description of operation.

Next, the operation of the washing machine having the above configuration will be described. As is well known, a washing process, a rinsing process, a dehydrating process, and a drying process are performed successively, but the washing process that characterizes the present invention will be described below, and the others will be omitted.
First, for example, an operation panel (not shown) is used to select and set the quality of the laundry (cotton, synthetic fiber, etc.), and the current flowing in the motor 7 is detected by the rotation of the drum 5 immediately after the start of operation. In particular, the amount of cloth is detected, and the cloth quality and the cloth amount result are input to a control device (not shown).

  Thereafter, the water supply valve 21 serving as the water supply means is opened and supplied to the water tub 2 as wash water through the water supply line 22, and when the water reaches the preset constant water level A, the pressure sensor 18 detects the water level. The water supply valve 21 is turned off and the water supply operation is stopped. While this water supply operation is performed, the drum 5 is driven by the motor 7 after the cloth amount detection, and the washing effect is moistened with water as soon as possible. This is advantageous for improvement.

  Then, the original beat washing operation is continued after reaching the above-mentioned constant water level A. For example, the drum 5 is driven to rotate at a low rotation speed of 50 rpm (for example, 40 to 60 rpm is preferable) effective for beat washing. Further, the tangling of the laundry is reduced by reverse driving at an appropriate interval. In addition, the circulation pump 14 is also driven substantially simultaneously (ON operation) and can be operated thereafter during the washing process, but is controlled to stop the operation (OFF operation) below a specific water level, as shown in FIG. ON / OFF control. As will be described in detail later, the circulation flow rate by the circulation pump 14 in consideration of the water level in the water tank 2 is controlled by this ON / OFF control.

  In the following, referring specifically to FIG. 2, when the water is supplied from the water supply valve 21 to the water tank 2 to the constant water level A through the water supply stroke as described above, the pressure sensor 18 detects this. Then, the circulation pump 14 is turned on following the drum 5 that has already been driven, and the operation is started. The water level detection by the pressure sensor 18 is performed by temporarily stopping the rotation of the drum 5 so that the water level can be accurately detected.

  As a result, the laundry is picked up and dropped in the drum 5 while washing is performed by the circulation pump 14 through the water absorption line 15 and the discharge line 16 as indicated by arrows in FIG. The water is discharged from the discharge port 16a facing the front opening of the drum 5 and poured so as to spray the laundry in the drum 5. Therefore, the normal laundry is in such a mode that when the laundry falls to the inner bottom of the drum 5, a part of the lower part is immersed in the washing water and gets wet. As a result, the detergent can be efficiently soaked in the entire laundry.

  As a result, the washing effect of the laundry sufficiently impregnated with the washing water is amplified, and the washing effect is greatly improved. In particular, in the initial operation of the washing process, the washing water (detergent solution) has not yet sufficiently permeated into the entire laundry, so that the washing water is actively poured by the circulation pump 14 immediately after the start of the washing operation. Therefore, an effective cleaning action can be obtained from the initial stage of the cleaning process, and an improvement in the cleaning effect can be expected.

  By the way, as shown in FIG. 2, the circulation pump 14 is repeatedly turned on and off according to the water level. The reason is that if the circulation pump 14 is continuously operated for a predetermined time, it is absorbed by the laundry. This is because the water content is increased and the water level in the water tank 2 is lowered. That is, in this embodiment, when the pressure drops to the low water level B just above the water inlet 15a, the pressure sensor 18 detects that the pressure has reached the first threshold value corresponding to the water level B, and controls this as an input signal. The apparatus stops the operation of the circulation pump 14 (OFF operation).

  As a result, the water level is prevented from lowering below the water intake port 15a, and the phenomenon of the air being sucked into the circulation pump 14 (hereinafter also referred to as air biting) is prevented. Then, while the operation of the circulation pump 14 is OFF, the washing operation is effectively advanced while the water level B is in a low water level B. Gradually, the washing water gradually drops due to gravity, an impact at the time of dropping, etc. As a result, the water level in the water tank 2 gradually rises.

  Eventually, when the water level recovers to the return water level C corresponding to the second threshold value, the circulation pump 14 is switched to operation ON again and is driven again, and the washing effect is promoted by pouring washing water into the laundry. Thereafter, the ON / OFF operation of the circulation pump 14 is repeatedly performed based on the detection that the pressure sensor 18 has reached the first or second threshold value in accordance with the fluctuation of the water level, so that the washing is performed. The circulation flow rate is controlled according to the water level while avoiding problems due to air biting and the like throughout the stroke, and is continued until the set time of the washing stroke is completed.

  In addition, in this embodiment, the pump flow rate of the circulation pump 14 itself can be adjusted according to the cloth quality and the amount of cloth, thereby improving the accuracy of the entire circulation flow rate described above. That is, as shown in FIG. 3, based on the cloth quality selected and set before the start of operation and the measurement result of the cloth amount immediately after the start, a water amount suitable for pouring water into the laundry, so-called pump flow rate, is determined. For example, cotton having high water absorption is set to a small amount compared to synthetic fiber.

  This is because cotton is easy to absorb water and has a large water content, so it can be effectively absorbed just by injecting a small amount of circulating water as washing water compared to synthetic fiber, and an effective cleaning action can be expected. The above setting of the circulating water remarkably accelerates the lowering of the water level in the water tank 2 and repeats the ON / OFF operation of the circulation pump 14 in a short cycle. This is because the ON operation time of the circulation pump 14 is shortened and the cleaning effect is reduced, and disadvantages such as disadvantageous to the durability of a pump motor (not shown) are caused. The setting of the pump flow rate of the circulation pump 14 itself can be easily handled by a known variable speed means such as changing the rotational speed by a duty ratio of a pump motor (not shown) or inverter control.

  The large amount of foaming phenomenon, which has been a problem in the past, will be described. Because of the small amount of washing water (detergent liquid), the detergent component foams due to impact such as stirring or discharging by the circulation pump 14. In particular, the tendency is further strengthened in the air-engaged state, and recently, the concentration of detergents has been increased in order to bring out the performance of the detergents, and the factor for generating a large amount of detergent bubbles is also increasing. However, in the present embodiment, a high-precision pressure sensor 20 is provided as a foam detection means via the heat exchanger 12 communicated with the water tank 2 so that a slight pressure change accompanying the generation of bubbles can be detected.

  Therefore, when the occurrence state of foam in which a large amount of foaming is expected is obtained as a threshold value and foaming is detected based on this, the operation of the circulation pump 14 is turned off and the pressure in the water tank 2 (pressure sensor 20) is reduced. The OFF state is maintained until the normal state is recovered. Thus, the condition setting is given priority over the above-described water level. For example, even if the water level recovers to the return water level C, the circulation pump 14 is not driven until the foaming state is recovered, and prompt foam calming is promoted. It will be.

  In addition, the foaming phenomenon tends to generate detergent bubbles rapidly due to agitation or impact when the water level is circulated with a small amount of water that lowers the water level and causes air biting. Since the circulation pump 14 is stopped before it occurs, it is possible to cope with the foaming phenomenon of such a situation, which is more convenient for preventing a large amount of foaming. Thereby, the detergent foam control means by the foam detection means may be adopted as necessary.

  Thus, the washing water is poured into the laundry by the circulation pump 14 so that the pump 14 is kept on and off so that the pump 14 is maintained at a water level that does not cause air biting. Since a suitable pump flow rate is determined in consideration of the amount of cloth, frequent ON and OFF cycles can be suppressed, and noise generated when air is caught due to air bubbles mixed in and the durability of the circulation pump 14 can be improved. In addition, an effective cleaning action is also taken into consideration, and in addition, a large amount of foaming phenomenon that is a concern can be suppressed in advance.

As described above, the present embodiment has the following effects.
While washing water is circulated into the laundry that is subjected to a tapping washing operation as a washing operation, the water content is promoted to improve the washing performance, and the circulation pump 14 is operated by a pressure sensor 18 in a water tank. 2 is constantly monitored and the flow rate is controlled so as to maintain the water level so that air is not sucked from the water intake port 15a of the circulation water channel, so that a large noise due to air biting in which bubbles are mixed in the pump 14 is not generated. In addition, detergent bubbles are more likely to be generated as the amount of circulating water becomes smaller as in the case of air chewing. However, since the effective flow rate can always be maintained in the ON operation of the pump 14, it is effective in suppressing a large amount of foaming phenomenon. In other words, useless idling of the circulation pump 14 can also be prevented.

  And as a concrete control means of the circulation flow rate by the above-mentioned circulation pump 14, in this embodiment, the pressure sensor 18 as the water level detection means has reached the lower water level B (first threshold value) or lower than the lower limit water level. In this case, since the circulation pump 14 is stopped (OFF), during operation (ON), the circulation pump 14 can be driven while reliably maintaining an effective water level without air biting. In addition, when the water level recovers during the stoppage and reaches the second threshold value corresponding to the return water level C, the operation can be resumed. This is because the operation is resumed based on the reliable recovery of the water level. In addition, setting the first and second threshold values for detecting each water level in the pressure sensor 18 can be easily handled.

  In addition, as disclosed in FIG. 3, in response to the water absorption due to the cloth quality of the laundry and the water content due to the amount of cloth, for example, cotton with good water absorption has a small amount with a slightly reduced pump flow rate. For fabrics with poor water absorption, such as synthetic fibers, the flow rate is increased to increase the amount of water poured into the laundry to promote the washing action. This is the pump flow rate that is suitable for circulating water depending on the laundry conditions. Can be set, and the control of the circulation flow rate can be further improved, and the cleaning operation can be performed efficiently without waste. In addition, since the water content increases as the amount of cloth increases, the water level in the normal water tank 2 decreases rapidly, and there is a possibility that the ON / OFF operation of the circulation pump 14 is frequently performed in order to prevent air jamming. By decreasing the pump flow rate as the amount increases, it is possible to suppress the above problems as much as possible.

  In addition, as described above, a large amount of bubbles are likely to be generated suddenly when the air biting or circulating water becomes extremely small. However, such a troubled driving situation can be avoided in advance, and in addition, In this embodiment, the tendency can be detected by the pressure sensor 20 before a large amount of bubbles is generated. For example, when the foaming phenomenon is detected, the circulation pump 14 is preferentially turned off. In the point of preventing foaming against the use of concentrated detergents, it can be dealt with before it reaches a large amount of foaming state, and foaming leaks out of the water tank 2 and the drum 5 rotates, etc. Is also very advantageous. However, as described above, the state in which detergent bubbles are likely to be generated is avoided by the ON / OFF operation of the circulation pump 14 according to the water level, so that the foam detection means may be employed as necessary.

(Modification 1)
FIG. 4 shows a modified example 1 of the first embodiment, and shows a modified example of the flow rate control means by the circulation pump 14 for the water level in the water tank 2. FIG. 4 is a diagram corresponding to FIG. It is.
In the above embodiment, the second threshold value preset in the pressure sensor 18 is detected as the means for re-driving the circulation pump 14 after waiting for the recovery of the water level in the flow rate control means. In this device, the OFF time of the circulation pump 14 is set in advance until the water level is recovered, and the operation is resumed as the time elapses.

  That is, the circulation pump 14 is driven at the constant water level A as shown in FIG. 4 and is stopped when it is detected that the first threshold value (low water level B) has been reached due to the drop in the water level. is there. However, even during the stoppage, the beat washing operation is continuously repeated, and the washing water swollen in the laundry is gradually discharged and the water level in the water tank 2 rises. Therefore, in this modified example, a predetermined return water level D is set, a time T required for recovery to the water level D is obtained by design or experiment, and the operation of the circulation pump 14 is resumed as the time T elapses. It is what I did.

  As described above, the circulation flow rate can be controlled by ON / OFF control of the circulation pump 14 by setting the time T to the predetermined return water level D in advance. In this case, the time T can be set in consideration of the quality of the cloth and the amount of cloth, so that more accurate operation control can be performed. Therefore, the air biting and the generation of a large amount of bubbles are effective as in the above embodiment. Therefore, the cleaning performance can be improved while the water level detecting means can be simplified.

(Modification 2)
5 and 6 show a second modification of the flow rate control means of the circulation pump 14 with respect to the water level in the water tank 2. FIG. 5 (a) is a diagram corresponding to FIG. 2, and FIG. 6) is an explanatory diagram of the operation of the pump flow rate control means of the circulation pump 14 itself corresponding to), and FIG. 6 shows a specific example for setting the pump flow rate.
This adopts substantially the same means as described in the first embodiment as the circulating flow rate control means for the water level in the water tank 2. That is, in response to detecting that the water level has reached the first or second threshold value by the pressure sensor 18, the circulation pump 14 is turned OFF or ON to control the circulation flow rate to prevent air jamming. Is common.

  However, this modified example 2 is characterized in that the pump flow rate of the circulation pump 14 itself can be varied according to the time S until the water level reaches the low water level B. The so-called first threshold value is used. This is different in that the time S until reaching the value is measured and the pump flow rate can be adjusted according to the length of the measurement time S. That is, it corresponds to the ON time from when the circulation pump 14 starts to be turned on until it is turned off. The time S until the first threshold value is reached depends on the water absorption and water content of the laundry. Fluctuate accordingly.

  Accordingly, the short time S until the first threshold value (low water level B) at which the circulation pump 14 stops is that the laundry is excellent in water absorption compared to synthetic fiber like cotton and has a large water content. It can be judged that this is the case of the cloth quality. Furthermore, the short measurement time S means that the circulation pump 14 is repeatedly turned on and off in a short cycle. As a result, not only the durability problem of the pump motor or the like occurs, but also the ON operation time is short. There is a problem that the water injection effect on the laundry is not sufficient and the desired cleaning effect is difficult to obtain.

  Therefore, in the second modification, the initial operation time S until the first threshold value is reached is measured as a reference, and as shown in FIG. 6, for example, the measurement time S is relatively long, such as 1 to 3 minutes. In the case of a short time, the flow rate reduction rate P is set to a pump flow rate Q1 with a 30% reduction from the initial flow rate Q0, and the drive control is performed. As a result, the amount of water to be poured into the laundry and the water content are reduced, and the water level in the water tank 2 is gradually lowered, so that the time until the first threshold value is reached, that is, the ON time of the circulation pump 14 is increased. it can.

This can improve the washing performance while avoiding frequent ON / OFF operations. In this case, it is possible to provide a flow rate control means suitable for laundry having excellent water absorption.
On the other hand, in the case of fabrics that are slightly inferior in water absorption, such as synthetic fibers, the water level decreases more slowly than the above cotton, and the frequent ON / OFF operations of the circulation pump 14 tend to be less. It is possible to improve the cleaning performance.

Incidentally, in FIG. 6, the initial flow rate Q0 is reduced by 10% even when the time S is 5 minutes or more at the maximum. However, the flow rate reduction rate P is obtained in consideration of the performance of the circulation pump 14 and the like. Alternatively, it may be a flow rate setting means for adjusting the amount.
In each of the above embodiments, the initial operation of the circulation pump 14 is started when the constant water level A is detected by the pressure sensor 18, and is not limited to this, for example, the same as the return water level C or D without waiting for the constant water level A. Alternatively, the circulation pump 14 may be driven when the equivalent water level is reached. In this case, the laundry in the drum 5 can be pre-watered and moistened together with the water supply operation prior to the original drum washing operation, which is the rotational drive of the drum 5, and is effective from the start of the drum washing operation. Clean action can be expected.

(Second Embodiment)
FIG. 7 shows a second embodiment of the present invention. Hereinafter, the same parts are denoted by the same reference numerals, and different parts will be described. . However, in the above embodiment, when the low water level B is reached, the circulation pump 14 is a means for controlling the circulation flow rate so as to wait for the recovery of the water level by the continuous washing operation with the circulation pump 14 turned off. The embodiment differs from the embodiment in that it is a circulating flow rate control means in which a squeezing operation is added to actively recover the water level.

  FIG. 7 (a) is a diagram corresponding to FIG. 2 and FIG. 7 (b) shows the rotation pattern of the drum 5 corresponding to the above (a), and in particular, the squeezing operation is performed. The points provided are shown. However, FIG. 7 (a) is the same as that of the first embodiment (FIG. 2), and will mainly be described with reference to FIG. 7 (b). Until now, the rotational speed of the drum 5 has been the same as that of the washing process. Since it was being executed, it was controlled at all times, for example, 50 rpm.

  On the other hand, in the present embodiment, the scrubbing operation is performed only when the circulation pump 14 is ON, and when the circulation pump 14 is OFF, the squeezing operation is performed by accelerating the rotational speed of the drum 5 from that of the scrubbing. It is characterized by that. This squeezing operation increases the rotational speed of the drum 5 to, for example, about 150 rpm, and is controlled to rotate so that the laundry has higher centrifugal force than gravity, although it is not as fast as normal dewatering operation. The range of about 100 rpm to 200 rpm is preferable.

  Thus, in the washing process of the present embodiment, the circulation pump 14 is driven after the completion of the water supply, and the washing process is performed in conjunction with the washing operation in which the drum 5 is appropriately reversely driven at the rotation speed of 50 rpm. Thereafter, when it is detected that the water level in the water tank 2 has dropped and the pressure sensor 18 has reached the first threshold value (low water level B), the circulation pump 14 is turned off and stopped, and the drum 5 is struck. One rotation is driven at a rotational speed of 150 rpm, which is accelerated about three times as much as washing, that is, instead of tapping washing, shifting to squeezing washing.

  In this squeezing, as described above, since the rotational speed is higher than the centrifugal force, the laundry is in a so-called weak dewatering operation state in which the laundry is held in the drum 5 without falling. Therefore, when the low water level B is reached, a part of the washing water contained in the laundry is actively squeezed out by the centrifugal force by this squeezing washing operation. As a result, the water level of the aquarium 2 at the low water level B is rapidly recovered by obtaining the squeezed wash water, reaches the second threshold value in a short time, and recovers to the return water level C. As a result, the squeezing washing operation is completed, and the water pouring action on the laundry is resumed by the normal tapping washing operation and the reactivation of the circulation pump 14.

  Thus, such an operation is repeatedly executed within a set time according to the washing process, which causes problems such as air biting by the circulation pump 14 and accompanying foaming and noise as in the above embodiments. The laundry can be washed effectively without any problems. In particular, in this embodiment, when the first threshold value (low water level B) is reached, the washing water is squeezed out by centrifugal action so that the water level in the water tank 2 can be recovered quickly, and thereafter Therefore, it is possible to smoothly execute the circulation of the washing water effective for the washing effect with respect to the subsequent washing operation.

  Further, since the water level is recovered quickly, the washing time and the stop time R of the circulation pump 14 can be shortened, in other words, the ON time can be set longer, and further improvement of the cleaning performance can be expected. In addition, since the squeezing washing operation is repeatedly performed, an action of extracting the soil components together with the washing water (detergent liquid) that has penetrated into the laundry is obtained, so that the washing performance can be advantageously developed. The rotation of the drum 5 in the above-described squeezing washing can be driven without any problem because the water level is lowered to the low water level B and the rotation is at a low speed.

  The present invention is not limited to the embodiments described above and shown in the drawings. For example, the return water level C at which the operation of the circulation pump is resumed is detected by setting the second threshold value. Not limited to this, the constant water level A may be regarded as the return water level and controlled. In addition, various modifications may be made without departing from the gist of the present invention, for example, the embodiments may be appropriately combined.

Sectional drawing which fractures | ruptures and shows the principal part of the whole structure of the drum-type washing machine with a drying function which shows 1st Example of this invention. Time chart showing the main part of the washing process Action explanatory diagram showing the relationship with the pump flow rate according to the fabric quality (b) and (b) FIG. 2 equivalent view showing the first modification FIG. 2 shows a modified example 2, (A) is a diagram corresponding to FIG. 2, (B) is an operation explanatory diagram showing the relationship of pump flow rate corresponding to (A). Action explanatory diagram showing control contents of pump flow rate FIG. 2 shows a second embodiment of the present invention, in which (A) is a view corresponding to FIG. 2, and (B) is an action explanatory diagram showing details of drum drive control corresponding to (A).

Explanation of symbols

  In the drawings, 1 is a housing, 2 is a water tank, 5 is a drum, 14 is a circulation pump, 15 is a water absorption line, 16 is a discharge line, 18 is a pressure sensor (water level detection means), and 20 is a pressure sensor (foaming detection). Means) and 21 are water supply valves (water supply means).

Claims (4)

A drum that rotates around a horizontal axis is provided in a water tank, and a circulating water channel that is connected to the upper and lower parts of the water tank via a water discharge port and a water suction port is provided, and a circulation pump is provided in the middle of the circulation water channel. ,
During the washing operation, the drum is rotated, and the circulation pump is driven to circulate the washing water, and the circulation pump circulates to maintain a water level that does not suck air from the water suction port during the washing water circulation. A drum-type washing machine characterized in that the flow rate is controlled.   A water level detecting means for detecting the level of the washing water in the aquarium is provided, and this water level detecting means detects that the water level in the aquarium has been lowered due to the circulation of the washing water and has reached a preset first threshold value. 2. The drum type washing machine according to claim 1, wherein the circulation flow rate is controlled by stopping the driving of the circulation pump.   When the water level detecting means detects that the water level in the aquarium has recovered and reached a second threshold value set in advance after the circulating pump is stopped, the circulating pump is driven again. The drum type washing machine according to claim 2. 2. The drum type washing machine according to claim 1, wherein an operation of accelerating the rotational speed of the drum and squeezing out the washing water contained in the laundry is added to the washing operation.

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