Patent Publication Number: US-8112904-B2

Title: Drum-type washer/dryer

Description:
FIELD OF THE INVENTION 
     The present invention relates to a drum-type washer/dryer provided with a heat pump drying mechanism. 
     BACKGROUND ART 
     One of the above-described drum-type washer/dryers is disclosed by Japanese Patent Publication No. 2004-135755 (Prior art document 1). The disclosed drum washer/dryer comprises a drum into which laundry is put and a water-receiving tub receiving water discharged from the laundry in the drum. A blowhole is provided in the water-receiving tub so that air is fed to an inner space of the drum therethrough. A duct is connected to the blowhole. The duct constitutes part of a looped circulation passage having a start and an end thereof in the inner space of the drum and is joined to the water-receiving tub. The drum washer/dryer comprises a condenser, an evaporator and a blower. The condenser is housed in the circulation passage so as to be located upstream of the duct. The evaporator is housed in the circulation passage so as to be located upstream of the condenser. The evaporator cools air drawn from the inner space of the drum, thereby dehumidifying the air. The condenser heats the air dehumidified by the evaporator, thereby increasing a temperature of the air. Laundry in the drum is dried by causing the air heated by the condenser to blow through the duct and the blowhole in turn. 
     DISCLOSURE OF THE INVENTION 
     Problem to be Overcome by the Invention 
     The drum-type washer/dryer disclosed in prior art document 1 is constructed to carry out a wash operation in an air circulation stopped state. In the wash operation, laundry is washed using water containing detergent. Accordingly, bubble flows back from the inner space of the drum through the blowhole into the duct during the wash operation. As a result, there is a possibility that the bubble flowed back into the duct may adhere to the condenser and the evaporator. 
     An object of the present invention is to provide a drum-type washer/dryer which can prevent the bubble flowed back into the duct from adhering to the condenser and the evaporator. 
     Means for Overcoming the Problem 
     The present invention provides a drum-type washer/dryer which incorporates a drum into which laundry is put and comprises a water-receiving tub receiving water discharged from the laundry in the drum, a blowhole provided in the water-receiving tub so that air is fed to an inner space of the drum therethrough, a duct connected to the blowhole, an air circulation passage having a start and an end thereof in the inner space of the drum and formed into a loop, the air circulation passage including the duct, a blower drawing air from the inner space of the drum and circulating the air in such a direction that the air is returned through the duct and the blowhole in turn into the inner space of the drum, a condenser provided in the circulation passage so as to be located upstream of the duct relative to the blowhole, an evaporator provided in the circulation passage so as to be located upstream of the condenser, and a compressor causing a refrigerant to flow into the evaporator and the condenser, characterized in that the duct includes a backflow preventing portion which serves as a resistance preventing backflow of a bubble when the bubble flows back from the inner space of the drum through the blowhole into an interior of the drum, the backflow preventing portion has a smaller cross-sectional area than a remaining portion of the duct, the cross-sectional area being obtained by fracturing the duct along a section line perpendicular to a flowing direction of the air in the duct. 
     Effect of the Invention 
     According to the invention, when a bubble in the drum flows back from the blowhole into the duct, the backflow preventing portion serves as a resistance to prevent the backflow of the bubble. Consequently, the bubble can be prevented from coming out of the duct thereby to adhere to the condenser and the evaporator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a drum washer/dryer of one embodiment of the invention; 
         FIG. 2  is a side view of the drum washer/dryer with an outer cabinet thereof being broken away, showing an inner construction; 
         FIG. 3  is a rear view of the drum washer/dryer with a rear plate being eliminated, showing an inner construction; 
         FIG. 4  is a sectional view taken along line  4 - 4  in  FIG. 5 ; 
         FIG. 5  is a front view of a water-receiving tub as viewed obliquely upward along a shaft center line of the tub; 
         FIG. 6A  is a rear view of a duct as viewed obliquely downward along the shaft center line; 
         FIG. 6B  is a section taken along line  6 B- 6 B in  FIG. 6A ; 
         FIG. 6C  is a section taken along line  6 C- 6 C in  FIG. 6A ; 
         FIG. 6D  is a section taken along line  6 D- 6 D in  FIG. 6A ; 
         FIG. 6E  is a section taken along line  6 E- 6 E in  FIG. 6A ; and 
         FIG. 7  is a rear view of the water-receiving tub as viewed obliquely downward along the shaft center line. 
     
    
    
     EXPLANATION OF REFERENCE SYMBOLS 
     Reference symbol  11  designates a water-receiving tub,  24  a drum,  34  an evaporator,  35  a condenser,  36  a compressor,  39  a blower,  40  a duct,  47  a blowhole,  48  a circulation passage,  52  a backflow preventing portion,  53  a control device,  54  a left duct, and  55  a right duct. 
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The invention will be described in more detail with reference to the accompanying drawings.  FIGS. 1 to 7  illustrate one embodiment of the invention. An outer cabinet  1  is constructed by joining a baseplate  2 , a left side plate  3 , a right side plate  4 , a front plate  5 , a ceiling plate  6  and a rear plate  7  to one another as shown in  FIG. 1 . The front plate  5  is formed with a circular access opening  8  as shown in  FIG. 2 . A circular door  9  is mounted on the front plate  5  so as to be pivotable between a closing state where the access opening  8  is closed by the door  9  and an open state where the access opening  8  is opened by the door  9 . 
     A plurality of dampers  10  are housed in the outer cabinet  1  as shown in  FIG. 2 . Each damper  10  employs oil as an operating fluid and a metal spring as a recovering spring and is fixed to the baseplate  2 . A water-receiving tub  11  made from a synthetic resin is mounted on rods of the dampers  10  thereby to be housed in the outer cabinet  1  in a damped and shock-absorbed state. The water-receiving tub  11  is formed into the shape of a bottomed cylinder with a closed rear and is disposed in such an inclined state that an imaginary shaft center line CL becomes lower from a front part thereof to a rear part thereof. The water-receiving tub  11  has a front end to which a water-receiving tub cover  12  is fixed. The cover  12  is formed into an annular shape and surrounds the water-receiving tub  11 . A bellows  13  made of rubber has a rear end fixed to an inner circumference of the water-receiving tub  12 . The bellows  13  is formed into a cylindrical shape and fixed to an inner circumference of the access opening  8 . 
     The rear plate of the water-receiving tub  11  is formed with a cylindrical motor support  14  as shown in  FIG. 4 . A cylindrical bearing bracket  15  is inserted into the motor support  14 . The bearing bracket  15  has an annular motor mounting  16  fixed to the rear plate of the water-receiving tub  11 . A drum motor  17  includes a stator  18  fixed to the motor mounting  16 . The drum motor  17  includes a rotor  19  rotatably mounted around the stator  18  and is accordingly formed into an outer rotor type. The drum motor  17  includes a rotational shaft  20  fixed to the rotor  19 . The rotational shaft  20  has a front end extending through the bearing bracket  15 , protruding into an interior of the water-receiving tub  11 . A front bearing  21  includes an outer ring fixed to an inner circumferential surface of the bearing bracket  15  so as to be located at a front end of the surface. A rear bearing  22  includes an outer ring fixed to the inner circumferential surface of the bearing bracket  15  so as to be located at a rear end of the surface. Each of the front and rear bearings  21  and  22  comprises a radial bearing including the cylindrical outer ring, an cylindrical inner ring having a smaller diameter than the outer ring and a plurality of balls interposed between the outer and inner rings. The rotational shaft  20  is fixed to inner rings of the front and rear bearings  21  and  22 , whereby the rotational shaft  20  is rotatably mounted in the bearing bracket  15 . A seal ring  23  is fixed to the bearing bracket  15 . The seal ring  23  has an inner circumference into which an outer circumference of the rotational shaft  20  is inserted so as to be in contact with the inner circumference of the seal ring  23 . As a result, the seal ring  23  watertightly seals a gap between the outer circumference of the seal ring  23  and the inner circumference of the bearing bracket  15 . 
     A drum  24  is fixed to the rotational shaft  20  of the drum motor  17  so as to be located in the water-receiving tub  11  as shown in  FIG. 4 . When the drum motor  17  is driven, the drum  24  is rotated together with the rotational shaft  20 . The drum  24  is housed in an inner space of the water-receiving tub  11  and constructed by joining an cylindrical body  25  and a circular bottom plate  26  both joined to each other. The bottom plate  26  has a triangular seat  27  as shown in  FIG. 5 . The seat  27  is screwed to the rotational shaft  20  thereby to be unrotatably fixed to the shaft  20 . Clothes are put through the bellows  13  and the water-receiving tub cover  12  in turn into the drum  24  while the door  9  is open. The clothes are taken out of the drum  24  through the water-receiving tub  12  and the bellows  13  in turn. 
     A plurality of openings  28  are circumferentially formed in the bottom plate  26  of the drum  24  at regular pitches as shown in  FIG. 4 . Each opening  28  is formed into a hole extending through the bottom plate  26  in the direction of thickness of the bottom plate. Each opening  28  is covered with a net plate  29  as shown in  FIG. 5 . Each net plate  29  is formed into such a mesh that both air and water are allowed to flow therethrough. The inner space of the drum  24  communicates via the plural net plates  29  with the inner space of the water-receiving tub  11 . The body  25  of the drum  24  is formed with a plurality of circulation holes  30  through which both air and water are allowed to be circulated, as shown in  FIG. 4 . The inner space of the drum  24  also communicates with the inner space of the water-receiving tub  11  through the circulation holes  30  as well as through the net plates  29 . 
     A water supply valve (not shown) is provided in the outer cabinet  1 . The water supply valve includes an input port connected to a faucet (not shown) and an output port connected to the inner space of the water-receiving tub  11 . Water is supplied from the faucet through the water supply valve into the water-receiving tub  11  when the water supply valve is opened. A drain hose  31  is connected to the water-receiving tub  11  as shown in  FIG. 2 . The drain hose  31  is provided with a drain valve (not shown). When the drain valve is closed, water cannot be discharged through the drain hose  31 . When the drain valve is opened, water is allowed to be discharged through the drain hose  31 . 
     A lower duct  32  is housed in the outer cabinet  1  so as to be located below the water-receiving tub  11  as shown in  FIG. 2 . The lower duct  32  is formed into the shape of a square pipe and extends straight in the front-back direction. The lower duct  32  has both front and rear faces which are open and is fixed to the baseplate  2 . A front hose  33  has a bellows-like lower end which is connected to the front face of the lower duct  32 . The front hose  33  has an upper end connected to the water-receiving tub cover  12 , whereby the inner space of the water-receiving tub  11  communicates via the front hose  33  with the inner space of the lower duct  32 . An evaporator  34  and a condenser  35  are provided in the lower duct  32 . 
     A compressor  36  is provided in the outer cabinet  1  so as to be located below the water-receiving tub  11 . The compressor  36  is fixed to the baseplate  2 . The compressor  36  has an outlet to which the condenser  35  is connected via a first relay pipe (not shown). The evaporator  34  is connected via a second relay pipe (not shown) to the condenser  35 . The compressor  36  has an inlet to which the evaporator  34  is connected via a third relay pipe (not shown). The second relay pipe is provided with a pressure regulator (not shown). The compressor  36  is disposed outside the lower duct  32 . During operation of the compressor  36 , a refrigerant discharged from the outlet of the compressor  36  is supplied to the condenser  35  and the evaporator  34  in turn, being returned from the evaporator  34  to the inlet of the compressor  36 . The compressor  36  includes a compressor motor (not shown) serving as a drive source. 
     A fan casing  37  is housed in the outer cabinet  1  so as to be located below the water-receiving tub  11 . The fan casing  37  has an inlet connected to the rear face of the lower duct  32 . The fan casing  37  is fixed to the baseplate  2 . A fan  38  is provided in the fan casing  37  and is connected to a rotational shaft of a fan motor (not shown). During operation of the fan motor, air in the drum  24  is sucked through the front hose  33  into the lower duct  32 . The sucked air is caused to pass through the evaporator  34  and the condenser  35  in turn, being sucked from the inlet of the fan casing  37  into the fan casing  37 . The fan motor is fixed to the fan casing  37  and constitutes a blower  38  together with the fan casing  37  and the fan  38 . 
     A duct  40  is fixed to a rear plate of the water-receiving tub  11  as shown in  FIG. 3 . The drum motor  17  is disposed so as to be surrounded by the duct  40 . The duct  40  is constructed by joining a rear duct cover  41  and a front duct cover  42  to each other into a tubular shape as shown in  FIGS. 6B to 6E . The rear duct cover  41  has an open front and the front duct cover  42  is formed into a plate-shape and closes the front of the rear duct cover  41 . The rear duct cover  41  has a lower end formed with an entrance  43  as shown in  FIG. 6A . The entrance  43  is formed into a cylindrical shape and has an outer circumference to which a bellows-like upper end of the rear hose  44  is connected as shown in  FIG. 7 . The rear hose  44  has a lower end connected to the outlet of the fan casing  37  as shown in  FIG. 2 . Air sucked into the fan casing  37  during operation of the fan motor is caused to pass through the outlet of the fan casing  37  and the entrance  43  of the rear hose  44  in turn thereby to enter the duct  40 , thereafter going upward in the duct  40  as shown by a broken line arrow in  FIG. 7 . The front duct cover  42  of the duct  40  is formed with a though-hole-like exit  45  as shown in  FIG. 6A . The exit  45  is disposed in an end of the front duct cover  42  opposed to the entrance  43 . Air flowing in the duct  40  exits from the exit  45 . 
     A vent hole  46  is formed in the motor mounting  16  as shown in  FIG. 4 . The vent hole extends through the motor mounting  16  in the thickness direction and is formed into the shape of a passage inclined downward from the front toward the rear. The vent hole  46  is disposed in front of the exit  45  of the duct  40  so as to be opposed to the exit  45 . Air exited from the exit  45  enters the vent hole  46 . A blowhole  47  is disposed ahead of the vent hole  46  so as to be opposed to the vent hole  46 . The blowhole  47  is formed into a cylindrical shape and extends through the rear plate of the water-receiving tub  11 . Air exited from the duct  40  enters through the vent hole  46  into the blowhole  47 . The blowhole  47  is designed to be opposed to one of a plurality of net plates  29  according to a mechanical rotational angle of the drum  24 . Air having entered into the blowhole  47  is capable of flowing linearly through one of the net plates  29  into drum  24 . 
     The hose  33 , the lower duct  32 , the rear hose  44  and the duct  40  constitute an air circulation passage  48  (see  FIG. 2 ) having a start and an end thereof in the inner space of the drum  24 . A blower  39  is provided for causing air to flow along the circulation passage  48 . The blower  39  draws air from the inner space of the drum  24  and circulates the air in such a direction that the air is returned through the duct  40  and the blowhole  47  in turn into the inner space of the drum  24 . The condenser  35  is disposed in the circulation passage  48  so as to be located upstream of the duct  40  relative to the blowhole  47 . The evaporator  34  is disposed in the circulation passage  48  so as to be located upstream of the condenser  35 . The evaporator  34 , the condenser  35 , the compressor  36  and the blower  39  constitute a heat pump type drying mechanism  49  (see  FIG. 2 ). The evaporator  34  cools air drawn from the drum  24  thereby to dehumidify the air. The condenser  35  applies heat to the air dehumidified by the evaporator  34 , thereby increasing the temperature of the air. More specifically, both evaporator  34  and condenser  35  generate high-temperature and low-humidity drying air. The drying air generated by the evaporator  34  and the condenser  35  is sent through the duct  40  and the blowhole  47  in turn into the drum  24 , so that laundry in the drum  24  is blasted by the high-temperature and low-humidity drying air. 
       FIG. 6B  is a section of the duct  40  taken along line  6 B- 6 B in  FIG. 6A .  FIG. 6C  is a section of the duct  40  taken along line  6 C- 6 C in  FIG. 6A .  FIG. 6D  is a section of the duct  40  taken along line  6 D- 6 D in  FIG. 6A .  FIG. 6E  is a section of the duct  40  taken along line  6 E- 6 E in  FIG. 6A . Lines  6 B- 6 B to  6 E- 6 E are cross-section lines intersecting a direction in which air flows in the duct  40 . The duct  40  is formed into such a helical shape that the duct  40  is curved so that an outer diameter Ro thereof is gradually decreased from entrance  43  toward the exit  45  with an inner diameter Ri being constant. The duct  40  has a low flow rate region  50  and a high flow rate region  51 . 
     The low flow rate region  50  refers to a region where a space broken along the cross-section line intersecting the direction in which air flows in the duct  40  has a rectangular section, as shown in  FIG. 6E . The low flow rate region  50  is set at the upper stream side which is the entrance  43  side. The high flow rate region  51  refers to a region where a space broken along the cross-section line intersecting the direction in which air flows in the duct  40  has a trapezoidal section, as shown in  FIGS. 6B to 6D . The high flow rate region  51  is set at the lower stream side which is the exit  45  side. The high flow rate region  51  has a cross-sectional area which is set at every part so as to be smaller than the minimum cross-sectional area of the low flow rate region  50 . As a result, air having entered into the duct  40  during operation of the fan motor flows at lower speeds in the low flow rate region  50  than in the high flow rate region  51  and flows at higher speeds in the high flow rate region  51  than in the low flow rate region  51 . 
     The duct  40  is formed with a backflow preventing portion  52  located in the high flow rate region  51  as shown in  FIG. 6A . The backflow preventing portion  52  is disposed at the top of the duct  40  which is the highest when the duct  40  is fixed to the water-receiving tub  11 . The duct  40  is formed into such a curved shape that the duct  40  has a left duct portion  54  extending leftward from the backflow preventing portion  52  serving as a starting point and a right duct portion  55  extending rightward from the backflow preventing portion  52  serving as a starting point.  FIG. 6C  shows a cross-sectional configuration of the backflow preventing portion  52 . The backflow preventing portion  52  is set in the high flow rate region  51  and accordingly, a space broken along a cross-sectional line intersecting the direction in which air flows in the duct  40  has a smaller cross-sectional area than every remaining portion of the duct  40 . 
     A control device  53  is provided in the outer cabinet  1  as shown in  FIG. 2 . The control device  53  is mainly composed of a microcomputer and has a central processing unit (CPU), a read only memory (ROM) and a random access memory (RAM). An operation control program is recorded on the ROM of the control device  53 . The CPU controls the drive motor  17 , a compressor motor, a fan motor, the water-supply valve and the drain valve based on the operation control program, thereby carrying out (1) a water-supply step to (9) a cooling step as described below. 
     (1) Water-Supply Step: 
     The drain valve is closed and the water-supply valve is opened so that water is stored in the water-receiving tub  11  with the water level in the water-receiving tub  11  according to the weight of the clothes. 
     (2) Wash Step: 
     The drum motor  17  is driven while both compressor motor and fan motor are stopped. Clothes in the drum  24  are raised upward while being stuck to the inner circumference of the drum  24 , and thereafter, the clothes are removed from the inner circumference of the drum  24  thereby to fall into the water in the water-receiving tub  11 , thereby being agitated. The wash step is carried out with detergent being dispensed into the water-receiving tub  11 . Accordingly, the clothes are caused to fall into the water containing the detergent thereby to be washed by a beat wash manner. In the wash step, the water surface is set to be lower than the blowhole  47  even when the weight of the clothes is at the maximum. Accordingly, since the blowhole  47  is open, bubbles produced in the water-receiving tub  11  would sometimes flow back through the blowhole  47  into the duct  40 . 
     (3) Drain Step: 
     The drain valve is opened so that water in the water-receiving tub  11  is discharged through the drain hose  31 . 
     (4) Water-Supply Step: 
     The drain valve is closed and the water-supply valve is opened so that water is stored in the water-receiving tub  11  so that a set water level according to the weight of clothes is reached. 
     (5) Rinse Step: 
     The drum motor  17  is driven while both compressor motor and fan motor are stopped. Clothes in the drum  24  are raised upward while being stuck to the inner circumference of the drum  24 , and thereafter, the clothes are removed from the inner circumference of the drum  24  thereby to fall into the water in the water-receiving tub  11 , thereby being agitated. The rinse step is carried out without dispensing detergent into the water-receiving tub  11 . Accordingly, the clothes are caused to fall into the water containing no detergent such that the detergent component is removed from the clothes. In the rinse step, the water surface is set to be lower than the blowhole  47  even when the weight of the clothes is at the maximum. Accordingly, since the blowhole  47  is open, bubbles produced in the water-receiving tub  11  would sometimes flow back through the blowhole  47  into the duct  40 . 
     (6) Drain Step: 
     The drain valve is opened so that water in the water-receiving tub  11  is discharged through the drain hose  31 . 
     (7) Dehydration Step: 
     The drum motor  17  is driven while both compressor motor and fan motor are stopped. The drum  24  is rotated while clothes are kept stuck to the inner circumference of the drum  24  without falling. In the dehydration step, water is centrifugally extracted from the clothes in the drum  24 . The water extracted from the clothes is received by the water-receiving tub, from which the water is discharged through the drain hose  31 . 
     (8) Drying Step: 
     The compressor motor and the fan motor are driven so that high-temperature low-humidity drying air is caused to blow against the clothes in the drum  24 . In the drying step, the drum motor  17  is driven so that clothes in the drum  24  are raised upward while being stuck to the inner circumference of the drum  24 , and thereafter, the clothes are removed from the inner circumference of the drum  24  thereby to fall, thus being agitated. The drying step corresponds to an operation for supplying drying air for drying the clothes in the drum  24  into the inner space of the drum  24 . 
     (9) Cooling Step: 
     The fan motor is driven with the compressor motor being stopped so that so that cooling air having a lower temperature than the drying air is caused to blow against the clothes in the drum  24 . The cooling air refers to air for which heat-exchange is not executed by the drying mechanism  49  or air with an ambient or room temperature. The cooling air is used to cool the clothes whose temperature has been increased in the drying step. In the cooling step, the drum motor  17  is driven so that clothes in the drum  24  are raised upward while being stuck to the inner circumference of the drum  24 , and thereafter, the clothes are removed from the inner circumference of the drum  24  thereby to fall, thus being agitated. The drying step corresponds to an operation for supplying drying air for drying the clothes in the drum  24  into the inner space of the drum  24 . The cooling step corresponds to an operation for supplying air having a lower temperature than the drying air into the inner space of the drum  24 . 
     The following effects can be achieved from the foregoing embodiment. The duct  40  is formed with the backflow preventing portion  52  having a locally smaller sectional area. Accordingly, when bubbles flow back through the blowhole  47  into the duct  40  in each of the wash and rinse steps, the backflow preventing portion  52  serves as a resistance thereby to prevent backflow of the bubbles. Consequently, since the bubbles having flowed back into the duct  40  is prevented from entering through the rear hose  44  into the fan casing  37 , the bubbles having flowed back into the duct  40  can be prevented from adhering to the condenser  35  and the evaporator  34 . 
     The backflow preventing portion  52  is located on the top of the duct  40 . Accordingly, when bubbles flow back through the blowhole  47  into the duct  40 , an amount of energy necessary to reach the backflow preventing portion  52  is increased. As a result, the bubbles cannot easily reach the backflow preventing portion  52 . Moreover, the bubbles having reached the backflow preventing portion  52  fall along the duct  40  to the blowhole  47  side without going over the backflow preventing portion  52 . Consequently, the bubbles cannot easily adhere to the condenser  35  and the evaporator  34 . 
     The water-receiving tub  11  is disposed in such an inclined state that an imaginary shaft center line CL becomes lower from a front part thereof to a rear part thereof. Accordingly, a space is defined between the rear plate of the water-receiving tub  11  and the vertical rear plate  7  of the outer cabinet  1 . The space has a widthwise dimension that is gradually reduced from a lower part to an upper part thereof. The duct  40  is joined to the rear plate of the water-receiving tub  11 . Consequently, since the duct  40  has a shape according to the space between the rear plate of the water-receiving tub  11  and the rear plate  7  of the outer cabinet  1 , the backflow preventing portion with the minimum sectional area can easily be formed on the top of the duct  40 . 
     The duct  40  has the left duct portion  54  extending leftward from the backflow preventing portion  52  serving as the starting point and the right duct portion  55  extending rightward from the backflow preventing portion  52  serving as the starting point. As a result, the backflow preventing portion  52  having the locally smaller sectional area is disposed in the middle of the duct  40 . Accordingly, when air passes the backflow preventing portion  52  during operation of the fan motor, a flow rate of air is rendered higher than immediately before air passes the backflow preventing portion  52 . Consequently, air can be supplied from the blowhole  47  through the net plate  29  into the drum  24  at a sufficient flow rate. Thus, since the drying air is blown against the clothes located away from the blowhole  47 , a drying degree of the clothes located away from the blowhole  47  can be improved. This effect can also be applied to the cooling air. 
     The low flow rate region  50  is provided at the entrance  43  side of the duct  40 , and the high flow rate region  51  is provided at the exit  45  side of the duct  40 . Accordingly, a flow rate at which air passes through the high flow rate region is higher than a flow rate at which air passes through the low flow rate region during operation of the fan motor. Air discharged from the blowhole  47  has a higher flow rate than when an entire region of the duct  40  except the backflow preventing portion  52  is set at the same constant sectional area as the low flow rate region. As a result, since air can be supplied from the blowhole  47  through the net plate  29  into the drum  24  at a sufficient flow rate, the drying air is blown against the clothes located away from the blowhole  47 , a drying degree of the clothes located away from the blowhole  47  can be improved. Moreover, the backflow preventing portion  52  is disposed in the high flow rate region  51 . Accordingly, since the flow rate of air discharged from the blowhole  47  is further increased, the drying degree of the clothes located away from the blowhole  47  can further be improved. This effect can also be applied to the cooling air. 
     The cooling step is carried out in addition to the drying step in which both compressor  36  and blower  39  are driven so that the drying air is supplied into the inner space of the drum  24 . In the cooling step, the blower  39  is driven with the compressor  36  being stopped so that the cooling air is supplied into the inner space of the drum  24 . Clothes whose temperature has been increased as the result of execution of the drying step can be cooled and thereafter be taken out. 
     The invention should not be limited to the foregoing embodiment. The embodiment may be modified as follows. The location of the backflow preventing portion  52  should not be limited to the top of the duct  40 . The backflow preventing portion  52  may be located in the middle of the duct  40  between the entrance  43  and the exit  45 . 
     The right duct portion  55  should not be limited to the curved shape but may be formed into a linear shape in which the right duct portion  55  extends horizontally in the longitudinal direction. 
     The low flow rate region  50  and the high flow rate region  51  are not essential constituents, but an entire region of the duct  40  except the backflow preventing portion  52  may be set at the same constant sectional area as the low flow rate region  50 , for example. 
     INDUSTRIAL APPLICABILITY 
     As described above, the drum-type washer/dryer of the invention is useful as a drum-type washer/dryer which can prevent bubbles produced in a drum from adhering to an evaporator and a condenser.