EP2458061B1

EP2458061B1 - Drum-type washing machine

Info

Publication number: EP2458061B1
Application number: EP11188720.4A
Authority: EP
Inventors: Katsuya Wakita; Toshihiko Yasui; Tadashi Asami; Tomoyuki Kikukawa; Wataru Uchiyama
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2010-11-24
Filing date: 2011-11-11
Publication date: 2016-06-15
Anticipated expiration: 2031-11-11
Also published as: CN102535087A; EP2458061A1; CN102535087B

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a drum-type washing machine for washing and drying laundry.

2. Description of the Related Art

A conventional drum-type washing machine with a drying function has a drying device which communicates with an inner part of a drum for sending air into the drum accommodating laundry. The drying device generally includes a dehumidifying portion for dehumidifying moist air carrying out dehumidification in contact with the laundry in the drum, a heating portion for heating the cooled and dehumidified air, a blower for sending the heated air into the drum, and an air duct for circulating the air in the drum.
The drum-type washing machine generates a bubble when the drum is rotated in a state in which washing water having a detergent dissolved therein is stored in a water tub at a washing step. In particular, in the case in which a user puts the detergent in a proper quantity or more for a degree of dirt or the case in which a rotating speed of the drum is high, a large quantity of bubbles are generated. For this reason, the bubble enters through a blowing port for sending air into the drum, thereby causing a defect on a drying device having an electric component such as a fan motor. Therefore, it is demanded to prevent the entrance of the bubble into the drying device.
For example, Unexamined Japanese Patent Publication No. 2006-136601 (hereinafter referred to as "Patent Document 1") discloses a drum-type washing machine for stopping a water supply and changing a time required for stirring or reducing a rotating speed of a drum to prevent an increase in a bubble, thereby preventing an entrance of the bubble into an air duct when detecting the generation of the bubble by turning on an electrode.
Moreover, Unexamined Japanese Patent Publication No. 2008-110002 (hereinafter referred to as "Patent Document 2") discloses a drum-type washing machine provided with a first conductivity sensor for detecting a concentration of a detergent and a second conductivity sensor for detecting a bubble entering an air duct, for example. If the concentration of the detergent is high, it is reduced through a water supply and drainage to prevent foaming. In the case in which the entrance of the bubble into the air duct is detected, furthermore, a rotation of a drum is stopped to prevent the entrance of the bubble into a blasting mechanism provided in the air duct.
In addition, a drum-type washing machine for blowing hot air onto the generated bubble, thereby disappearing the bubble is disclosed in Unexamined Japanese Patent Publication No. 2008-73126 (hereinafter referred to as "Patent Document 3"), for example.
The conventional drum-type washing machine described in Patent Document 3 will be described below with reference to Fig. 5. Fig. 5 is a schematic structure view of the conventional drum-type washing machine.
As shown in Fig. 5, the drum-type washing machine includes heater unit 60, draft air duct 55 for circulating air in drum 51, and foaming detecting sensor 56 provided in an upper part at a back side in water tub 53. Heater unit 60 has heater 61 for heating air and blasting fan 59 for sending
Brief description will be given to an operation to be carried out when a bubble is generated at a washing step of the drum-type washing machine.
First of all, a proper quantity of water for a quantity of clothes 52 to be washed which are put in drum 51 is supplied into water tub 53 and drum 51 is then rotated to start washing. At this time, if a quantity of a detergent is larger as compared with the dirt of clothes 52 to be washed, a large quantity of bubbles 54 are generated and enter draft air duct 55 through which warm air is sent in drying.
When bubble 54 generated in water tub 53 and drum 51 comes in contact with foaming detecting sensor 56 and is thus detected, an air duct communicates from outside air inlet 58 to draft air duct 55 by means of intake control valve 57. Consequently, outside air is introduced into draft air duct 55 by means of blasting fan 59 so that the outside air is heated by heater 61 in heater unit 60 provided in the middle of an inner part of draft air duct 55. Then, the heated air is sent in a direction of an arrow shown in Fig. 5 and hot air is blown into drum 51 from blasting hole 62. At this time, when generated bubble 54 is heated by the hot air, the air in bubble 54 expands. For this reason, the shape of bubble 54 cannot be maintained so that bubble 54 is broken and disappeared. Consequently, an entrance of the bubble into the air duct is prevented.
Furthermore, a drum-type washing machine for driving an air blower to prevent an entrance of a bubble into an air duct at a washing step is disclosed in Unexamined Japanese Patent Publication No. 2008-6063 (hereinafter referred to as "Patent Document 4"), for example.
However, the drum-type washing machines described in Patent Documents 1 and 2 stop a supply of washing water and change a time required for stirring when detecting the generation of a bubble during in an operation. For this reason, a time required for washing is prolonged. Moreover, there is a problem in that water and a detergent are wasted because of an excessive water supply when the washing water is additionally supplied and draining is then carried out to reduce a concentration of the detergent.
Referring to the drum-type washing machine described in Patent Document 3, furthermore, there is a problem in that a quantity of power consumption in washing is increased because a large energy is required for heating to generate defoaming hot air.
In addition, referring to the drum-type washing machine described in Patent Document 4, a duct for a drying unit is large-sized and an air blower is therefore provided in a lower part, for example. Consequently, a bubble entering an air duct and a liquefied bubble falls along an inside wall of an air duct by gravity. For this reason, the falling bubble is sent and returned to a water tub by means of the air blower. Therefore, efficiency is poor.
When a drum is rotated at such a high speed that laundry sticks to an inner peripheral surface of the drum at a washing step, a washing effect can be enhanced. On the other hand, when the high speed rotation is carried out, a bubble tends to be generated and is apt to enter an air duct. For this reason, it is necessary to simultaneously implement contrary functions for preventing the entrance of the bubble causing deterioration in reliability while enhancing the washing effect.

SUMMARY OF THE INVENTION

A drum-type washing machine according to the present invention includes a housing, a water tub supported in the housing, a drum provided rotatably in the water tub, a motor for rotating and driving the drum, an air duct having a sucking port and a blowing port which introduce air into the drum, a blower provided in the air duct for sending the air into the drum, a bubble detecting portion for detecting a bubble entering the air duct, and a control portion for controlling at least one of a washing step of washing laundry with a low speed rotation in which the laundry is subjected to beat washing in the drum and a high speed rotation in which the laundry sticks to an inner peripheral surface of the drum, a rinsing step and a dewatering step, and at the washing step, the control portion operates the bubble detecting portion, operates the blower to send air to the blowing port from above the blowing port when the bubble detecting portion detects the entrance of the bubble, and causes the bubble to flow from the blowing port toward the water tub side.
Consequently, it is not necessary to prolong a time required for washing also in the case in which the bubble is detected at the washing step. Therefore, it is possible to lessen power consumption. Moreover, it is possible to efficiently prevent the entrance of the bubble into the air duct and to enhance a washing effect with the high speed rotation of the rotating drum.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 shows a sectional view of a drum-type washing machine according to a first exemplary embodiment of the present invention;
Fig. 2 shows a perspective view of a main part of an air duct of the drum-type washing machine according to the first exemplary embodiment of the present invention;
Fig. 3 shows a time chart for explaining a washing step of the drum-type washing machine according to the first exemplary embodiment of the present invention;
Fig. 4 shows a perspective view of a main part of an air duct of a drum-type washing machine according to a second exemplary embodiment of the present invention; and
Fig. 5 shows a schematic structure view of a drum-type washing machine according to the related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An exemplary embodiment according to the present invention will be described below with reference to the drawings. Note that, the present invention is not restricted to the exemplary embodiment.

FIRST EXEMPLARY EMBODIMENT

Fig. 1 is a sectional view showing a drum-type washing machine according to a first exemplary embodiment of the present invention. Fig. 2 is a perspective view showing a main part of an air duct in the drum-type washing machine. Fig. 3 is a time chart showing an operation of a washing step in the drum-type washing machine. In Figs. 1 and 2, an arrow a indicates a direction in which air flows and an arrow b indicates a direction in which a bubble entering air duct 10 flows.
As shown in Figs. 1 to 3, the drum-type washing machine according to the present exemplary embodiment includes at least housing 1, water tab 3, drum 4, motor 9, air duct 10, blasting fan 13 to be a blower, bubble detecting portion 21, and control portion 25.
Water tank 3 is swingably supported into housing 1 by means of damper 2 or the like. Cylindrical bottomed drum 4 is rotatably provided in water tub 3. Drum 4 has rotating shaft 5 which is downward inclined from an opened front side toward a back side to be a bottomed portion (for example, approximately 10 degrees).
Openable door 24 is provided on an inclined surface at the front side of housing 1 opposite to opening portion 8 of drum 4. Door 24 serves to put laundry A in/out of drum 4. For example, a plurality of baffles 6 and a large number of water passing holes 7 are provided on an inner peripheral surface of drum 4. Baffles 6 are protruded inward in a direction of rotating shaft 5. Water passing holes 7 communicate with an inner part of water tub 3.
Washing water is supplied into water tab 3 by means of a water supply valve (not shown) to be a water supply portion for supplying the washing water into water tub 3, and the washing water supplied into water tub 3 is supplied from water passing hole 7 into drum 4. On the other hand, the washing water in water tub 3 is discharged to an outside of the washing machine via drainage passage 23 by opening drainage valve 22 provided below drum 4 after washing laundry A.
Motor 9 for rotating and driving drum 4 is attached to a rear surface of water tub 3. Motor 9 is constituted by a brushless DC motor, for example, and is rotated and driven with a rotating speed varied freely by an inverter control.
Heat pump device 17 is provided above water tub 3. Heat pump device 17 is constituted by compressor 18, condenser 16, expansion portion 19 and evaporator 15, and conduit 20 and heat pump device 17 are coupled to each other in order to circulate a refrigerant. Compressor 18 compresses the refrigerant. Condenser 16 is a heating portion for radiating heat of the compressed refrigerant having a high temperature and a high pressure, thereby heating passing air. Expansion portion 19 is constituted by a capillary tube or the like, for example, and reduces a pressure of the refrigerant having a high pressure. Evaporator 15 serves as a dehumidifying portion in which the refrigerant having the pressure reduced dehumidifies air drawing heat from surroundings and passing.
Air duct 10 for introducing the air from the rear surface of water tub 3 into drum 4 is provided to reach the rear surface of water tub 3 from above water tub 3. Air duct 10 has sucking port 12 provided in front of an upper surface of water tub 3 and blowing port 11 provided on the rear surface of water tab 3, and sucking port 12 is disposed above blowing port 11. The air in water tub 3 and drum 4 is supplied from sucking port 12 of water tub 3 to air duct 10, and is blown toward blowing port 11 from above blowing port 11 provided on an outlet side of air duct 10 and is thus supplied into water tub 3 and drum 4.
Moreover, air duct 10 includes evaporator 15 and condenser 16 in heat pump device 17, blasting fan 13 to be driven by fan motor 14, and bubble detecting portion 21. Evaporator 15, condenser 16 and blasting fan 13 are provided sequentially from sucking port 12 along an air flow above water tub 3.
The air sent by blasting fan 13 is cooled and dehumidified in evaporator 15 of heat pump device 17 and is heated in condenser 16. Then, the air heated in the condenser 16 is sent by blasting fan 13 so as to be blown down from above blowing port 11 provided on the rear surface of water tub 3 through air duct 10 which is downward extended toward blowing port 11. Consequently, the air circulates into water tub 3 and drum 4. The air which draws moisture in contact with laundry A in drum 4 and thus becomes moist returns from sucking port 12 to air duct 10, and flows from a forward part toward a rear part above water tab 3 and thus circulates.
Moreover, control portion 25 provided in housing 1 drives motor 9, compressor 18 of heat pump device 17, fan motor 14 to be a blower and the like, and successively controls each of washing, rinsing, dewatering and drying steps. Control portion 25 includes a signal processing portion for processing a bubble detection signal output from bubble detecting portion 21 which will be described below in detail.
A bubble detecting portion 21 according to the present invention will be described below with reference to Fig. 2.
As shown in Fig. 2, bubble detecting portion 21 is constituted by at least one pair of electrodes provided close to each other at predetermined interval K on an inner peripheral surface of air duct 10 opposite to each other in a perpendicular direction to an axial direction of air duct 10, and is formed to take a shape of a plate or a needle. Bubble detecting portion 21 is provided in the vicinity of blowing port 11 of air duct 10 and detects a bubble entering air duct 10. When the bubble entering air duct 10 comes in contact with the electrodes, the electrodes are conducted to each other so that a current flows to detect the bubble.
In another example, the electrodes may be provided vertically or transversely on a substrate so as to be separated hollowly in air duct 10 and placed in close positions. Furthermore, bubble detecting portion 21 may detect a bubble according to a quantity of light transmission other than an electrical conduction.
In the drum-type washing machine having the structure described above, the operation and function will be described below with reference to Fig. 1.
First of all, door 24 provided openably on the front surface side of housing 1 is opened to put laundry A into drum 4 through opening portion 8. Next, a power switch (not shown) of operating portion 26 provided in a front part of an upper surface of housing 1 is turned ON. When a start switch (not shown) is manipulated to start an operation, a quantity of a cloth in laundry A which is put in is detected by cloth quantity detecting portion 27.
Subsequently, washing is executed in order of a washing step, a rinsing step and a dewatering step. Based on a time chart of Fig. 3, an operation of the washing step will be described below in detail. The washing step is started subsequently to the decision of the quantity of the cloth in laundry A which is put in.
First of all, when a quantity of water which is preset by the detected quantity of a cloth in the laundry A is introduced into water tab 3, a user puts a detergent in a predetermined quantity. At this time, the washing water supplied into water tab 3 is fed from water passing hole 7 into drum 4.
Next, control portion 25 drives motor 9 and rotates drum 4 at a low speed. Consequently, laundry A is lifted up in a rotating direction of drum 4 by means of baffle 6 provided in drum 4 and falls from an upper part in drum 4 by gravity. At this time, the rotating speed of drum 4 is set to be 30 r/min to 50 r/min, for example, and a mechanical force such as a shock in the fall is effectively applied to laundry A to carry out washing. Although the rotating speed of drum 4 also depends on the quantity of laundry A, it is preferably 40 r/min.
As shown in Fig. 3, next, normal and reverse rotating operations of drum 4 are alternately repeated so that laundry A is rotated at a low speed in drum 4 and is thus subjected to beat washing.
At the washing step, subsequently, the low speed rotation for carrying out the beat washing over laundry A is carried out and high speed rotation washing in which laundry A sticks to the inner peripheral surface of drum 4 which will be described below is then performed.
The rotating speed of drum 4 in the high speed rotation is set to be 150 r/min to 300 r/min, for example, and washing water contained in laundry A is forcedly discharged by a centrifugal force. It is preferable that the rotating speed of drum 4 should be 200 r/min. Although the high speed rotation is executed at least once at the washing step, it may be executed at plural times. While a time required for the high speed rotation is set to be shorter than a time required for the low speed rotation, the low speed rotation and the high speed rotation are repetitively carried out. Consequently, drum 4 is rotated at a high speed to remove the washing water between fibers of laundry A by a centrifugal force and to continuously substitute the washing water between the fibers. Thus, a washing effect can be enhanced.
At the washing step, however, the washing water having a detergent dissolved therein is stored in a bottom part of water tub 3. When the rotating speed of drum 4 is set to be 200 r/min, for example, and drum 4 is thus rotated at a high speed, therefore, the washing water is stirred so that a bubble is generated.
Therefore, control portion 25 rotates drum 4 at a high speed, and at the same time, turns ON bubble detecting portion 21 to bring a state in which the bubble entering air duct 10 can be detected. At this time, when the entering bubble comes in contact with the electrodes to carry out a conduction so that bubble detecting portion 21 detects the entrance of the bubble, blasting fan 13 is operated. Then, the air is sent to be blown down toward blowing port 11 from above blowing port 11 so that the bubble entering air duct 10 is caused to flow out of blowing port 11 toward water tub 3 side.
Also in the case in which the bubble entering air duct 10 is liquefied in air duct 10, consequently, the liquefied bubble is prevented from flowing toward blasting fan 13 provided in air duct 10 or the like. Consequently, it is possible to easily push the bubble out of air duct 10 toward water tub 3 side by sending the air.
Then, the air is sent so that the bubble is pushed back toward water tub 3 side. Consequently, the bubble is no longer present between the electrodes in bubble detecting portion 21. Therefore, the bubble is not detected by bubble detecting portion 21. When the bubble is not detected, bubble detecting portion 21 makes a transition from the high speed rotation (for example, 200 r/min) to the low speed rotation (for example, 40 r/min) over drum 4 to turn OFF a power supply of bubble detecting portion 21 as shown in Fig. 3.
Thereafter, blasting fan 13 is stopped after predetermined time t1 passes since the transition from the high speed rotation to the low speed rotation in drum 4. Consequently, bubble detecting portion 21 is turned ON to bring a state in which the entrance of the bubble can be detected only in the high speed rotation of drum 4 in which the generation of the bubble is increased at the washing step. As a result, power consumption is lessened as compared with the case in which bubble detecting portion 21 is usually turned ON, and furthermore, the bubble in air duct 10 is caused to flow toward water tub 3 side more reliably, thereby preventing the entrance of the bubble into heat pump device 17 or the like.
Next, the rinsing step is executed subsequently to the washing step. The rinsing step is the same as the washing step. More specifically, control portion 25 rotates drum 4 at a high speed, and at the same time, turns ON bubble detecting portion 21 to bring a state in which the bubble entering air duct 10 can be detected. In only the high speed rotation of drum 4 in which the generation of the bubble is increased at the rinsing step, consequently, bubble detecting portion 21 is turned ON to bring a state in which the entrance of the bubble can be detected. As a result, power consumption can be lessened as compared with the case in which bubble detecting portion 21 is usually turned ON, and furthermore, the entrance of the bubble into air duct 10 can be prevented precisely.
As described above, the drum-type washing machine according to the present invention operates bubble detecting portion 21 to detect the bubble entering air duct 10 in the high speed rotation of drum 4 in at least the washing step. When bubble detecting portion 21 detects the entrance of the bubble into air duct 10, then, blasting fan 13 is operated to send air so as to be downward blown toward blowing port 11 from above blowing port 11 so that the bubble in air duct 10 is pushed and returned toward water tub 3 side.
Also in the case in which the bubble entering air duct 10 is liquefied in air duct 10, consequently, the liquefied bubble falls along an inside wall of an air duct 10 by gravity and flows toward water tank 3 side. Therefore, the bubble is hindered from being liquefied to enter air duct 10. Thus, it is possible to efficiently prevent the bubble from entering blasting fan 13 provided in air duct 10 or the like.
Moreover, the entrance of the bubble into air duct 10 can be prevented efficiently. Therefore, the high speed rotation of drum 4 can be carried out at the washing step. Consequently, it is possible to sufficiently discharge a large quantity of washing water contained in laundry A from the laundry by a centrifugal force generated with the high speed rotation and to effectively remove the washing water having dirt dissolved therein from a fiber, thereby enhancing the washing effect. As a result, it is possible to simultaneously implement the prevention of the entrance of the bubble into air duct 10 and the high washing effect.
Although control portion 25 rotates drum 4 at a high speed, and at the same time, bubble detecting portion 21 is turned ON to bring a state in which the bubble entering air duct 10 can be detected in the present exemplary embodiment, the present invention is not restricted thereto. Also when control portion 25 rotates drum 4 at a low speed, bubble detecting portion 21 may be turned ON to bring a state in which the bubble entering air duct 10 can be detected. Consequently, it is possible to prevent the bubble from entering air duct 10 irrespective of the rotating speed of drum 4.

SECOND EXEMPLARY EMBODIMENT

Fig. 4 is a perspective view showing a main part of air duct according to a second exemplary embodiment of the present invention. The present exemplary embodiment is different from the first exemplary embodiment in that a plurality of bubble detecting portions 21 is provided in air duct 10 from air blowing port 11 to blasting fan 13. The other structures are the same as those of the first exemplary embodiment and the same structures have the same reference numerals, and detailed description of the first exemplary embodiment will be incorporated by reference.
As shown in Fig. 4, a plurality of bubble detecting portions 21 is correspondingly provided at predetermined interval L with respect to a direction (a direction of arrow b) in which a bubble entering air duct 10 flows in order of first sensor 21a, second sensor 21b and third sensor 21c upward from blowing port 11 in three places in air duct 10.
In general, if a quantity of generation of the bubble is large, the bubble enters blasting fan 13 of air duct 10 in a short time. Therefore, control portion 25 varies a quantity of air to be sent by blasting fan 13 according to a time interval between signals detected by bubble detecting portion 21 (first sensor 21a, second sensor 21b or third sensor 21c). Consequently, unnecessary blasting can be reduced and the bubble can be efficiently pushed out of air duct 10 reliably.
More specifically, control portion 25 sets the quantity of air to be sent by blasting fan 13 to be larger than a predetermined value when the time interval between signal detected by bubble detecting portion 21 (for example, a time internal from first sensor 21a to second sensor 21b or from second sensor 21b to third sensor 21c) is shorter. Herein, it is assumed that the predetermined value is set to be a quantity of blast obtained immediately before the air is sent by blasting fan 13. Consequently, time intervals from a start of detection to first sensor 21a, from first sensor 21a to second sensor 21b and from second sensor 21b to third sensor 21c are measured. As a result, a bubble is pushed back in an optimum quantity of blast in which an entrance is prevented against an increase situation of the bubble so that the entrance of the bubble into the air duct can be prevented precisely.
A relationship between time intervals of detection signals in the sensors and a quantity of blast will be described below with reference to Table 1.
Table 1 shows the relationship between the time intervals between signals detected by first sensor 21a, second sensor 21b and third sensor 21c and the quantity of the air sent by blasting fan 13. Referring to the quantity of blast, for example, an output of 100% of a blast capability in blasting fan 13 is set to be "large", an output of 50% is set to be "middle" and an output of 20% is set to be "small".

[Table 1]

Table 1

		Time interval of detection signal (sec)
		0 < t ≤ 3	3 < t ≤ 5	5 < t
Bubble detecting portion	First sensor	Small	-	-
	First to second sensors	Middle	Small	Small
	Second to third sensors	Large	Middle	Small

First of all, drum 4 is rotated at a high speed, and at the same time, a time that first to third sensors 21a to 21c are turned ON is set to be a detection starting time.
Next, duration t from the start of the detection to an entrance of a bubble generated in water tab 3 and drum 4 into air duct 10 through blowing port 11 and a contact with first sensor 21a is detected by control portion 25. At this time, as shown in Table 1, if a duration from the start of the detection to the contact with first sensor 21a and the detection of the entrance of the bubble through first sensor 21a is equal to or less than three seconds, the quantity of blast through blasting fan 13 is set to be "small" and the air is sent. On the other hand, if a duration from the start of the detection to the contact with first sensor 21a and the detection of the entrance of the bubble through first sensor 21a is more than three seconds, blasting fan 13 is not driven but a stopping state is maintained.
Subsequently, the entrance of the bubble is detected by first sensor 21a and is then detected by second sensor 21b provided in an upper part of air duct 10 at interval L. At this time, if a duration from the detection of the bubble through first sensor 21a to the detection of the bubble through second sensor 21b is equal to or less than three seconds, it can be decided that the bubble is continuously increased speedy and enters air duct 10. Therefore, control portion 25 increases the quantity of blast through blasting fan 13 from "small" to "middle".
If a duration from the detection of the bubble through first sensor 21a to the detection of the bubble through second sensor 21b is more than three seconds and is equal to or less than five seconds, it can be decided that an increase in the bubble entering air duct 10 is suppressed. Therefore, control portion 25 controls to set the quantity of blast into "small" and to continuously carry out blasting until the detection signal from first sensor 21a is eliminated, and to push the bubble back. On the other hand, if a duration from the detection of the bubble through first sensor 21a to the detection of the bubble through second sensor 21b is more than five seconds, it can be decided that the entrance of the bubble is suppressed. Therefore, control portion 25 controls to maintain the quantity of blast to be "small" and to continuously carry out the blasting until the detection signal from first sensor 21a is eliminated, and to push the bubble back.
If a duration from the detection of the bubble through first sensor 21a to the detection of the bubble through second sensor 21b is equal to or less than three seconds, then, it is decided that the entrance speed of the bubble is greater. Therefore, the entrance of the bubble is detected through second sensor 21b and is thereafter detected through third sensor 21c provided in the upper part of air duct 10 at interval L. At this time, if a time interval of the detection of the bubble from second sensor 21b to third sensor 21c is equal to or less than three seconds, it can be decided that the bubble is further increased continuously and speedy and enters air duct 10 even if the output is "middle" under blasting. Therefore, control portion 25 controls to set the quantity of blast through blasting fan 13 from "middle" to "large" and to push the bubble out of air duct 10 in the quantity of blast at a maximum output (100 %).
If a duration from the detection of the bubble through second sensor 21b to the detection of the bubble through third sensor 21c is more than three seconds and is equal to or less than five seconds, moreover, it can be decided that the entrance speed of the bubble entering air duct 10 is increased and the bubble enters air duct 10 even if the blasting is carried out at an output of "small". Therefore, control portion 25 increases the quantity of blast through blasting fan 13 from "small" to "middle".
On the other hand, if a duration from the detection of the bubble through second sensor 21b to the detection of the bubble through third sensor 21c is more than five seconds, it can be decided that the entrance of the bubble into air duct 10 is suppressed. Therefore, control portion 25 controls to maintain the quantity of blast through blasting fan 13 to be "Small" and to continuously carry out the blasting until the detection signal from first sensor 21a is eliminated, and to push the bubble back.
As described above, according to the present exemplary embodiment, the time intervals for the detection of the bubble through bubble detecting portions 21 are measured. Consequently, it is possible to push the bubble back from air duct 10 in an optimum quantity of blast which prevents the entrance of the bubble according to the time interval. As a result, the entrance of the bubble into air duct 10 can be prevented more efficiently.
Although the quantity of blast is controlled according to the time interval of the detection signal in Table 1 according to the present exemplary embodiment, the present invention is not restricted thereto. In the present invention, for example, the control may be carried out according to a speed at which the bubble reaches each bubble detecting portion 21. Consequently, it is possible to reliably prevent the bubble from entering air duct 10.
Although the quantity of blast is set to be "small" if the bubble reaches first sensor 21a in three seconds or less in Table 1 according to the present exemplary embodiment, moreover, the present invention is not restricted thereto. For example, blasting fan 13 may be driven by setting the case in which the bubble reaches first sensor 21a in one second or less into "large" and setting the case in which the bubble reaches first sensor 21a in two seconds or less into "middle". Consequently, it is possible to detect the bubble with higher precision.
Although the quantity of blast is varied according to the time interval between signals detected by bubble detecting portions 21 (first sensor 21a, second sensor 21b and third sensor 21c) in the present exemplary embodiment, moreover, the present invention is not restricted thereto. For example, the quantity of blast may be varied according to an arrival time from when detecting is started to when the bubble arrives at bubble detecting portion 21 of first sensor 21a, second sensor 21b and third sensor 21c, or speed during the time. Consequently, air in the quantity of blast according to the arrival duration or speed of the bubble can be blown onto the bubble. As a result, power consumption can be lessened and the entrance of the bubble into the air duct can be prevented reliably. At this time, moreover, it is also possible to carry out a control to detect the bubble through first sensor 21a and to then turn ON second sensor 21b, and to detect the bubble through second sensor 21b and to thereafter turn ON third sensor 21c, thereby starting the detection. Consequently, it is possible to reduce the power consumption more greatly.
Although bubble detecting portions 21 (first sensor 21a, second sensor 21b and third sensor 21c) are provided in the vicinity of blowing port 11 of air duct 10 in the present exemplary embodiment, furthermore, the present invention is not restricted thereto. For example, it is also possible to employ a structure in which first sensor 21a is provided on blowing port 11 of air duct 10 and second sensor 21b is provided in a position at a predetermined interval in a blasting direction (a direction of arrow b), and third sensor 21c is not provided. At this time, control portion 25 controls to vary the quantity of blast according to a time interval or a speed for the detection of the entrance of the bubble in contact with second sensor 21b by setting, as a starting point, a time that the bubble is detected through first sensor 21a provided on blowing port 11. Consequently, the air in the quantity of blast according to the arrival time or speed of the bubble can be blown onto the bubble. As a result, the power consumption can be lessened and the entrance of the bubble into air duct 10 can be prevented more precisely.
Although there is employed the structure in which control portion 25 controls to continuously carry out sending air until the detection signal from bubble detecting portion 21 is eliminated if it is decided that the increase in the bubble entering air duct 10 is suppressed in the exemplary embodiment, moreover, the present invention is not restricted thereto. For example, if a resistance value or a current which is detected by bubble detecting portion 21 has a certain value, the blasting may be stopped. Consequently, a duration for driving blasting fan 13 is shortened. Therefore, the power consumption can be reduced more greatly.
Although blower 13 is operated when bubble detecting portion 21 detects the entrance of the bubble in the exemplary embodiment, moreover, the present invention is not restricted thereto. For example, when drum 4 makes a transition to a high speed rotation and blower 13 is simultaneously operated, the air can be sent from blowing port 11 before the entrance of the bubble is detected by bubble detecting portion 21. Also in the case in which the generation of the bubble is increased, consequently, it is possible to prevent the entrance of the bubble from blowing port 11 into air duct 10.
In the exemplary embodiment, moreover, a pair of electrodes in bubble detecting portion 21 is provided close to each other in air duct 10. In the case in which the bubble is scattered in the high speed rotation of drum 4 and enters air duct 10 from blowing port 11, consequently, the entrance of the bubble can be reliably detected even if the bubble is not linked to washing water in water tab 3. As a result, even if the bubble enters air duct 10, it can be discharged from air duct 10 to an outside of blowing port 11 through blasting.

Claims

A drum-type washing machine comprising:
a housing (1);

a water tub (3) supported in the housing (1);

a drum (4) provided rotatably in the water tub (3);

a motor (9) for rotating and driving the drum (4);

an air duct (10) having a sucking port (12) and a blowing port (11) which introduce air into the drum (4);

a blower (13) provided in the air duct (10) for sending the air into the drum (4);

a bubble detecting portion (21) for detecting a bubble entering the air duct (10); and

a control portion (25) for controlling at least one of a washing step of washing laundry with a low speed rotation in which the laundry is subjected to beat washing in the drum (4) and a high speed rotation in which the laundry sticks to an inner peripheral surface of the drum (4), a rinsing step and a dewatering step,

wherein at the washing step, the control portion (25) operates the bubble detecting portion (21), operates the blower (13) to send air to the blowing port (11) from above the blowing port (11) when the bubble detecting portion (21) detects the entrance of the bubble, and causes the bubble to flow from the blowing port (11) toward the water tub side, characterized in that

the bubble detecting portion (21) comprises a pair of electrodes, and the pair of electrodes are provided on an inner peripheral surface of the air duct (10) opposite to each other in a perpendicular direction to an axial direction of the air duct (10).
The drum-type washing machine according to claim 1, wherein at the washing step with the high speed rotation, the control portion (25) operates the bubble detecting portion (21), and operates the blower (13) to cause the bubble to flow toward the water tub side when the bubble detecting portion (21) detects the entrance of the bubble.
The drum-type washing machine according to claim 1, wherein the bubble detecting portion comprises a plurality of detecting portions (21 a, 21b, 21c) provided in a direction in which the bubble entering the air duct flows.
The drum-type washing machine according to claim 3, wherein the plurality of detecting portions (21a, 21b, 21c) are provided at a predetermined interval (L) in the air duct (10) from the air blowing port (11) to the blower (13) in a direction in which the bubble entering the air duct (10) flows.
The drum-type washing machine according to claim 3, wherein the control portion (25) varies a quantity of air to be sent by the blower (13) according to a time interval between signals detected by the bubble detecting portion (21).
The drum-type washing machine according to claim 5, wherein the control portion (25) sets the quantity of air to be sent by the blower (13) to be larger than a predetermined value when the time interval between the signal detected by two neighboring of the bubble detecting portions (21a, 21b, 21c) is shorter.
The drum-type washing machine according to any one of claims 1 to 6, wherein at the rinsing step of rinsing the laundry with the low speed rotation in which the laundry is subjected to beat washing in the drum (4) and the high speed rotation in which the laundry sticks to the inner peripheral surface of the drum (4), the control portion (25) activates the bubble detecting portion (21) in the high speed rotation of the drum (4) to detect the bubble.