JP7488035B2 - Clothes dryer - Google Patents

Description

An embodiment of the present invention relates to a clothes dryer.

Conventionally, drum-type clothes dryers that use a heat pump have been known as clothes dryers (see, for example, Patent Document 1). This drum-type clothes dryer is configured so that an air inlet and an exhaust port are provided in a water tub that has a rotatable drum with many holes in which clothes are stored, a circulating air passage that connects the air inlet and the exhaust port outside the water tub is provided together with a fan device for blowing air, and the evaporator and condenser of the heat pump are disposed in the circulating air passage to supply dry air into the water tub.

As a result, the moist air discharged from inside the drum is dehumidified by passing through the evaporator, then heated by passing through the condenser, and is supplied again into the drum as high-temperature dry air. This heat pump system dries clothes at a lower temperature than the heater system, so there is less damage to clothes caused by heat, and it is possible to reduce power consumption and time. In recent years, multi-flow type heat exchangers, which have higher heat exchange efficiency than the conventional fin tube type, have been adopted for the condenser and evaporator.

Patent No. 5979434

However, in this type of clothes dryer, when the drying operation is started in a low room temperature environment, the temperature of the refrigerant in the evaporator may drop too much, causing frost to form in the evaporator. This may cause the fins of the evaporator to freeze, blocking part of the ventilation passage and reducing the heat exchange efficiency. In the above-mentioned Patent Document 1, when frost forms on the evaporator, the compressor is controlled to melt the frost, but since this is a measure taken after the frost has formed, the drying time becomes long.
Therefore, the present invention provides a clothes dryer that can effectively prevent frosting and freezing of the evaporator and maintain good drying performance.

The clothes dryer of the embodiment includes a drum provided within a main body for storing clothes, a circulation air duct provided outside the drum to communicate between an exhaust port for discharging air from the drum and an air inlet for blowing air into the drum, a blower for circulating air within the drum through the circulation air duct, a heat pump duct connected to an exhaust duct connected to the exhaust port and constituting a part of the circulation air duct, a heat pump including a compressor and an evaporator and a condenser disposed within the heat pump duct, an exhaust opening provided in the exhaust duct for discharging air within the circulation air duct to the outside, and an exhaust damper for opening and closing the exhaust opening. the heat pump duct, a room temperature sensor for detecting the ambient temperature outside the heat pump, an evaporator temperature sensor for detecting the temperature at the inlet of the evaporator, and a control device for controlling each of the mechanisms to perform a drying operation, wherein at the start of the drying operation, if the temperature detected by the room temperature sensor is a low temperature equal to or lower than a first predetermined temperature, the control device performs an evaporator frost prevention operation to open the exhaust damper, and when the temperature detected by the evaporator temperature sensor exceeds a second predetermined temperature that is lower than the first predetermined temperature during the execution of the evaporator frost prevention operation, the control device terminates the evaporator frost prevention operation .

FIG. 1 is a vertical sectional right side view showing an internal configuration of a washing/drying machine according to a first embodiment of the present invention. FIG. 1 is a longitudinal sectional rear view showing an internal configuration of a washer/dryer including a heat pump; Rear perspective view of the washer-dryer FIG. 1 is a perspective view of the lint filter and its surroundings with a portion of the top plate of the outer box broken away FIG. 1 is a block diagram showing an electrical configuration of a washing/drying machine; A flowchart showing a control procedure executed by the control device when starting a drying operation. FIG. 13 is a diagram showing changes in the condenser temperature, the inlet temperature, and the outlet temperature of the evaporator over time when the room temperature is 20° C. FIG. 13 is a diagram showing changes in the condenser temperature, the inlet temperature, and the outlet temperature of the evaporator over time at the start of a drying operation when the room temperature is 5° C. and the evaporator frost prevention operation is not performed. FIG. 13 is a diagram showing the change in the inlet temperature and outlet temperature of the evaporator over time at the start of a drying operation when the room temperature is 5° C. and an evaporator frost prevention operation is performed. 10 is a flowchart showing a control procedure executed by the control device at the start of a drying operation according to a second embodiment. 10 is a flowchart showing a control procedure executed by the control device at the start of a drying operation according to a third embodiment.

Below, several embodiments of a drum-type washer/dryer equipped with a heat pump and having both a washing function and a drying function will be described with reference to the drawings. In the following embodiments, common parts will be given the same reference numerals, and new illustrations and repeated explanations will be omitted.

(1) First embodiment The first embodiment will be described with reference to Figs. 1 to 9. First, the overall configuration of a washer/dryer 1 as a clothes dryer according to this embodiment will be described with reference to Figs. 1 to 5. As shown in Fig. 1 etc., an outer box 2 constituting the main body of the washer/dryer 1 is substantially rectangular box-shaped, and a cylindrical water tub 3 is supported in the outer box 2 in a state inclined downward toward the rear via an elastic support mechanism (not shown). A cylindrical rotating drum 4 (hereinafter simply referred to as "drum 4") is rotatably supported in the water tub 3 as a drum in which clothes to be washed are stored. The drum 4 is configured to rotate around an inclined axis that extends in the front-rear direction and is inclined slightly downward toward the rear from the horizontal.

As shown in FIG. 1, the peripheral and rear walls of the drum 4 are formed with a number of holes 4a for water and air passage, and the inner surface of the peripheral wall of the drum 4 is provided with a number of baffles (not shown) for agitating the laundry. Although not shown in detail, the front of the drum 4 is provided with a circular opening through which the laundry is put in and taken out, and the front of the water tub 3 is provided with an input port 3a that is connected to the opening. The front of the outer box 2 is provided with a door 5 for opening and closing the input port 3a. An operation panel 6 is provided at the top of the front of the outer box 2. Although not shown in detail, the operation panel 6 is provided with a display section and an operation section.

As shown in Figures 1 and 2, a drum motor 8, which is an outer rotor type brushless motor, for example, constituting a drive mechanism, is disposed at the rear of the water tub 3. As shown in Figure 1, the tip of the rotating shaft of this drum motor 8 penetrates the back surface of the water tub 3, protruding into the water tub 3, and is connected and fixed to the center of the rear of the drum 4. With this configuration, the drum 4 is directly driven to rotate by the drum motor 8. In this case, the drum 4 is continuously rotated in the forward direction, that is, clockwise as viewed from the front, during the spin cycle. During the washing, rinsing, and drying cycles, the drum 4 repeatedly rotates forward and backward.

Although not shown in detail, a water supply mechanism is provided in the upper part of the outer box 2 to supply water from a water supply source to the water tank 3 and the like. This water supply mechanism is configured to include a water supply valve 7 (shown only in FIG. 5). On the other hand, as shown in FIG. 1, a drainage pipe 12 is connected to the lower part of the water tank 3, and a drainage valve 13 is provided in the middle of this drainage pipe 12. When water is supplied to the water tank 3 by the water supply mechanism with the drainage valve 13 closed, the water is stored in the water tank 3. At this time, the water level in the water tank 3 is detected by a water level sensor (not shown). When the drainage valve 13 is opened, the water stored in the water tank 3 is discharged outside the machine through the drainage pipe 12. In addition, a room temperature sensor 14 is provided in the outer box 2 near the drainage pipe 12. This room temperature sensor 14 is, for example, a thermistor, and detects the room temperature, which is the atmospheric temperature outside the heat pump 15 in the outer box 2.

As shown in FIG. 1, the water tub 3 is provided with an exhaust port 17 at the upper right of the front part for discharging air from inside the drum 4, and an air intake port 18 at the upper left of the rear part for supplying dry air into the drum 4. As shown in FIG. 1 and FIG. 2, a hot air supply mechanism 19 is provided inside the outer box 2 for circulating and supplying dry air, i.e., hot air, into the drum 4 to perform the clothes drying operation.

The hot air supply mechanism 19 is located outside the water tank 3 and is equipped with a circulating air duct 20. The inlet of the circulating air duct 20 is connected to the exhaust port 17 of the water tank 3, and the outlet of the circulating air duct 20 is connected to the air supply port 18. The hot air supply mechanism 19 is equipped with a heat pump 15 that dehumidifies and heats the circulating air to generate dry air. In addition, the hot air supply mechanism 19 is equipped with a blower fan 16 that circulates the air discharged from the exhaust port 17 through the circulating air duct 20 in the direction of arrow A while supplying it from the air supply port 18 to the water tank 3 and ultimately to the drum 4.

As shown in Figs. 1 and 2, the circulating air passage 20 specifically includes an upper exhaust duct 21, a rear exhaust duct 22, a heat pump duct 24, and an air supply duct 25. The upper exhaust duct 21 and the rear exhaust duct 22 form an exhaust duct. As shown in Fig. 1, the upper exhaust duct 21 is connected at its base end to the exhaust port 17 and extends rearward from the upper right side of the outer box 2, and the upper end of the rear exhaust duct 22 is connected to its tip. A well-known lint filter 26 for capturing lint from the dry air is provided in the middle of the upper exhaust duct 21 so as to be removable from the outer box 2. As shown in Figs. 3 and 4, the lint filter 26 includes a cover plate 26a having a handle 26b on its upper surface, and the cover plate 26a is arranged facing the upper surface of the outer box 2.

As shown in FIG. 4, an exhaust opening 9 is provided at the top of the middle part of the upper exhaust duct 21, located behind the lint filter 26, for discharging the internal air from the top surface of the outer box 2. As shown in FIG. 3, the exhaust opening 9 is connected to the outer box exhaust port 2a provided on the top surface of the outer box 2. As shown in FIG. 1, an exhaust damper 10 is provided for opening and closing the exhaust opening 9. The exhaust damper 10 is opened and closed by a drive mechanism consisting of a damper motor 11 (shown only in FIG. 5) and the like. By opening the exhaust damper 10, a part of the air flowing in the circulating air passage 20 can be discharged from the exhaust opening 9 through the outer box exhaust port 2a to the outside of the outer box 2.

As shown in FIG. 2, the rear exhaust duct 22 has a rectangular cross section and extends downward from the rear of the water tank 3, with its lower end connected to the right end, which is the base end, of the heat pump duct 24. The heat pump duct 24 has a rectangular cross section and extends left to right in the rear bottom area inside the outer box 2. At this time, as shown in FIG. 2, the evaporator 27 and condenser 28 that constitute the heat pump 15 are arranged in order from right to left (left to right in FIG. 2) inside the heat pump duct 24. And, an outside air intake 23 for taking in outside air is provided between the evaporator 27 and the condenser 28 on the upper wall of the heat pump duct 24.

As shown in FIG. 2, the blower fan 16 is provided at the tip side (the right end side in FIG. 2) of the heat pump duct 24. This blower fan 16 is configured, for example, with a centrifugal fan 33 and a fan motor 34 that drives it inside a fan casing 32. The lower end, which is the base end of the air supply duct 25, is connected to the outlet of the fan casing 32. The air supply duct 25 extends upward behind the aquarium 3 on the left side inside the outer box 2, and the upper end, which is the tip end, is connected to the air supply port 18.

The heat pump 15 is configured by connecting a compressor 29, the condenser 28, a throttle valve 30 as a pressure reducing means, and the evaporator 27 in a closed loop by a refrigerant pipe 31. A required amount of refrigerant is sealed inside the heat pump 15 and circulates through the refrigerant pipe 31. At this time, the condenser 28 functions as a heating means for heating the dry air, and the evaporator 27 functions as a dehumidifying means for removing moisture from the dry air. In this embodiment, the evaporator 27 and the condenser 28 are configured as so-called multi-flow type heat exchangers, and are configured as a rectangular block that is slightly thin in the air flow direction as a whole. As is well known, a multi-flow type heat exchanger is configured by alternately stacking flat plates having multiple refrigerant flow holes therein and heat exchange fins, connecting one end side of the multiple flat plates with an inlet side header portion, and connecting the other end side of the multiple flat plates with an outlet side header portion.

In this heat pump 15, as shown by the flow of refrigerant in FIG. 2 with arrow B, when the compressor 29 is driven, the gas refrigerant discharged from the compressor 29 flows into the condenser 28, where it is condensed by heat exchange into liquid refrigerant. The liquid refrigerant flowing out of the condenser 28 is expanded by the throttle valve 30 into mist, and the mist refrigerant flows into the evaporator 27. Then, in the evaporator 27, the refrigerant is vaporized by heat exchange with the outside air, and the gas refrigerant is returned to the compressor 29. The refrigerant is further compressed by the compressor 29, where it is discharged at a high temperature and high pressure, thus completing the circulation.

When the heat pump 15 is driven, the blower fan 16 is also driven, and as shown by the arrow A in Figures 1 and 2, the air in the water tank 3, i.e., the drum 4, flows from the exhaust port 17 through the upper exhaust duct 21 and the rear exhaust duct 22, and then to the heat pump duct 24. At this time, as the air passes through the upper exhaust duct 21, the lint filter 26 or the like captures the lint contained in the air.

The air that has passed through the rear exhaust duct 22 then flows through the heat pump duct 24, passes through the evaporator 27 and the condenser 28 in order, then flows into the air intake duct 25, and is then circulated through the air intake port 18 and the hole 4a before being supplied into the drum 4. This air circulation causes the air that has absorbed moisture from the water tub 3, i.e. the clothes in the drum 4 and contains a large amount of steam, to pass through the evaporator 27 in the heat pump duct 24 and cool, causing the steam to condense or sublimate and become dehumidified. The dehumidified air then passes through the condenser 28 and is heated to become dry warm air, which is then supplied back into the drum 4 to dry the clothes.

As shown in FIG. 2, the heat pump 15 is provided with a number of temperature sensors, such as thermistors, in its main parts to detect the temperature of the refrigerant. That is, a discharge temperature sensor 35 is provided near the discharge port of the compressor 29. A condenser temperature sensor 36 is provided in the condenser 28. An evaporator temperature sensor 37 is provided in the evaporator 27. An inlet temperature sensor 38 is provided near the inlet of the compressor 29.

Furthermore, as shown in FIG. 1, the circulation air duct 20 is also provided with a plurality of dry air temperature sensors, for example thermistors, for detecting the temperature of the dry air. Specifically, an air inlet temperature sensor 39 is provided near the air inlet 18, and an exhaust air temperature sensor 40 is provided in the rear exhaust duct 22. As shown in FIG. 1, a control device 41, which is mainly composed of, for example, a microcomputer and controls the entire washer/dryer 1, is provided inside the outer casing 2.

Figure 5 shows a schematic diagram of the electrical configuration of the washer/dryer 1, with a focus on the control device 41. That is, the control device 41 receives operation signals from the operation section of the operation panel 6 and controls the display on the display section of the operation panel 6. The control device 41 also receives detection signals from the room temperature sensor 14, discharge temperature sensor 35, condenser temperature sensor 36, evaporator temperature sensor 37, inlet temperature sensor 38, air supply port temperature sensor 39, and exhaust temperature sensor 40.

The control device 41 controls the water supply valve 7, the drain valve 13, the drum motor 8, the fan motor 34 of the blower fan 16, the compressor 29 and throttle valve 30 of the heat pump 15, the damper motor 11, etc. With the above configuration, the control device 41 controls each mechanism of the washer/dryer 1 based on input signals from each sensor and pre-stored control programs according to the operation course set by the user on the operation panel 6, and automatically performs the well-known washing operation consisting of a washing process, a rinsing process, and a spin-drying process, and a drying operation. At this time, when performing the drying operation, the control device 41 drives and controls the compressor 29 of the heat pump 15 and the blower fan 16, etc., based on the temperatures detected by the room temperature sensor 14 and each temperature sensor 35 to 40, and rotates the drum 4. Note that during normal drying operation, the exhaust damper 10 is in a closed state.

Now, in this embodiment, as described in the next operation explanation (flowchart explanation), the control device 41 executes an evaporator frost prevention operation that opens the exhaust damper 10 when the room temperature tr detected by the room temperature sensor 14 is a low temperature equal to or lower than a first predetermined temperature at the start of the drying operation. More specifically, the first predetermined temperature is set to 5°C. However, when the detected room temperature tr is below freezing point, ie, 0°C or lower, the drying operation and the washing operation themselves are not performed. Also, in this embodiment, this evaporator frost prevention operation is executed for a certain time T0 from the start of the drying operation. The certain time T0 is set to any time within a range of 10 to 25 minutes, for example, 20 minutes.

Next, the operation of the washer/dryer 1 configured as described above will be described with reference to Figs. 6 to 9. The flow chart in Fig. 6 shows the procedure executed by the control device 41 during the drying operation, mainly for preventing frost formation on the evaporator. That is, in step S1, when the drying operation is started, the compressor 29 of the heat pump 15, the blower fan 16, and the drum 4 are driven. In step S2, the room temperature tr detected by the room temperature sensor 14 is read. In step S3, it is determined whether the detected room temperature tr is a low temperature equal to or lower than the first predetermined temperature, 5°C in this case. As mentioned above, it is assumed that the detected room temperature tr is higher than 0°C.

If the room temperature tr detected by the room temperature sensor 14 is above 5°C (No in step S3), the process proceeds to step S7, where normal drying operation control is performed. On the other hand, if the room temperature tr detected by the room temperature sensor 14 is a low temperature of 5°C or less (Yes in step S3), the process proceeds to step S4, where an evaporator frost prevention operation is performed. Here, if the room temperature tr is as low as 5°C or less and the drying operation is continued as is, the refrigerant temperature flowing through the evaporator 27 may excessively drop below freezing, causing frost to form on the surface of the evaporator 27. However, in this embodiment, the exhaust damper 10 is opened in the evaporator frost prevention operation in step S4 by controlling the damper motor 11.

As a result of this evaporator frost prevention operation, as shown in FIG. 1, the air flowing in the circulating air passage 20 in the direction of arrow A passes through the lint filter 26 in the upper exhaust duct 21, and a portion of it is discharged from the exhaust opening 9 as shown by arrow C. As the air is discharged from the exhaust opening 9, outside air, i.e., the air inside the outer box 2, is drawn into the heat pump duct 24 from the outside air intake 23 provided in the heat pump duct 24 as shown by arrow D in FIG. 2. Even if the evaporator 27 is at a low temperature, for example below 0°C, the outside air drawn in from the outside air intake 23 has a positive temperature and is higher than the temperature of the evaporator 27. In addition, since the outside air intake 23 is located between the evaporator 27 and the condenser 28, the low-temperature air that has passed through the evaporator 27 mixes with the outside air, increases in temperature, and passes through the condenser 28, gradually increasing the temperature of the circulated air.

By opening the exhaust damper 10 in this way, the cold air circulating through the air circulation duct 20 is replaced with warmer air, preventing the evaporator 27 from remaining at a low temperature or becoming even colder, and allowing the temperature to rise. This allows the temperature of the evaporator 27 to rise quickly from a state below 0°C, and prevents frost and freezing even if moist air passes through the evaporator 27.

Returning to FIG. 6, in step S5, it is determined whether a predetermined time T0 (e.g., 20 minutes) has elapsed since the start of the evaporator frost prevention operation. If the predetermined time T0 has not elapsed (No in step S5), the evaporator frost prevention operation in step S4 continues. If the predetermined time T0 has elapsed (Yes in step S5), the evaporator frost prevention operation is terminated in step S6 and the exhaust damper 10 is returned to the closed state. Thereafter, normal drying operation control is performed in step S7.

Figures 7 to 9 show how the temperature of the condenser 28 and the inlet and outlet temperatures of the evaporator 27 change over time at the beginning of the drying operation. Figure 7 shows the case where the room temperature is, for example, 20°C, Figure 8 shows the case where the room temperature is, for example, 5°C and the evaporator frost prevention operation is not performed, and Figure 9 shows the case where the room temperature is, for example, 5°C and the evaporator frost prevention operation is performed. Note that in Figure 9, the condenser temperature is omitted and the temperature change between the evaporator 27 and the condenser 28 is added.

Now, as shown in FIG. 7, even if the room temperature is relatively high, when the drying operation is started and the compressor 29 is driven, the temperature of the refrigerant inside the heat pump 15 drops rapidly due to heat exchange in the condenser 28, and the inlet temperature of the evaporator 27 drops further from 0°C, for example, to about -20°C. However, because the temperature of the condenser 28 rises rapidly due to the action of the compressor 29, the temperature of the evaporator 27 also starts to rise after a few minutes, and returns to 0°C or higher after, for example, about 10 minutes. In this case, in the early stages of drying when the temperature of the clothes in the drum 4 is rising and no moisture has evaporated from the clothes yet, frosting or freezing does not occur even if the inlet temperature of the evaporator 27 is a low temperature below 0°C. Then, after a certain time T0 (for example, 10 to 25 minutes) has passed since the start of drying, the inlet temperature of the evaporator 27 also reaches a positive temperature above 0°C, so frosting or freezing of the evaporator 27 does not occur.

In contrast, as shown in FIG. 8, if the room temperature at the start of the drying operation is low, for example 5°C, the temperature of the air flowing through the circulating air duct 20 does not rise easily in the early stages of drying, the condenser 28 is not sufficiently heated, and the temperature of the evaporator 27 does not rise either. Therefore, even if a certain time T0 has passed since the start of drying, the inlet temperature of the evaporator 27 remains below 0°C and does not rise to a positive temperature, and when moist air passes through the evaporator 27, frost forms on the surface of the evaporator 27, which may cause freezing.

However, in this embodiment, even if the room temperature at the start of the drying operation is low, for example 5°C, the evaporator frost prevention operation is executed from the start of drying as described above, and the exhaust damper 10 is opened. This allows the inlet temperature of the evaporator 27 to be raised to a positive temperature by a certain time T0, as shown in Figure 9. As a result, frost and freezing in the evaporator 27 can be prevented. Note that if the room temperature tr is relatively high at the start of the drying operation, exceeding 5°C in this case, the evaporator frost prevention operation is not executed, and the drying operation can be quickly carried out under normal control.

In this way, the washer-dryer 1 of this embodiment can provide the following effects. That is, in this embodiment, the control device 41 is configured to execute an evaporator frost prevention operation that opens the exhaust damper 10 when the room temperature tr detected by the room temperature sensor 14 is a low temperature of 5°C or less, which is the first predetermined temperature, at the start of the drying operation. This allows the temperature of the evaporator 27 to be raised relatively quickly, and frost and freezing of the evaporator 27 can be prevented. In this case, frost prevention of the evaporator 27 is achieved by control at the start of the drying operation, rather than by taking measures after frost has occurred, so that frost prevention measures can be taken early. Therefore, according to this embodiment, it is possible to obtain the excellent effect of effectively preventing frost while preventing the drying time from becoming unnecessarily long.

In addition, in this embodiment, the evaporator frost prevention operation is configured to be performed for a certain time T0 from the start of the drying operation. In this case, if the evaporator frost prevention operation is performed longer than necessary, the efficiency of the drying will decrease and the drying time will be longer, so it is desirable to end the evaporator frost prevention operation at the certain time T0, and frost can be effectively prevented. Furthermore, in this embodiment, the first predetermined temperature is set to 5°C. As described in the explanation of Figure 7, it has been revealed that in reality, if the room temperature tr exceeds 5°C, there is almost no risk of frost or freezing even if a normal drying operation is performed, so it is desirable to perform the evaporator frost prevention operation when the room temperature is below 5°C.

(2) Second, third and other embodiments The flowchart in Fig. 10 shows a second embodiment, and shows a processing procedure mainly related to the evaporator frost prevention operation executed by the control device 41 during drying operation. The second embodiment differs from the flowchart in Fig. 6 of the first embodiment in that the control device 41 continues to execute the evaporator frost prevention operation when the detected temperature te of the evaporator temperature sensor 37 is a second predetermined temperature, for example, a low temperature below 0°C, after executing the evaporator frost prevention operation for a certain period of time.

In other words, in the flow chart of FIG. 10, the drying operation is started in step S1, and the room temperature tr detected by the room temperature sensor 14 is read in step S2. In step S3, it is determined whether the detected room temperature tr is a low temperature, which is a first predetermined temperature (in this case, 5°C or less), and if the room temperature tr detected by the room temperature sensor 14 is a low temperature of 5°C or less (Yes in step S3), the evaporator frost prevention operation is executed in step S4. Then, in step S5, when it is determined that a predetermined time T0 (e.g., 20 minutes) has elapsed since the start of the evaporator frost prevention operation (Yes in step S5), the temperature te of the inlet part of the evaporator 27 detected by the evaporator temperature sensor 37 is read in step S11.

In the next step S12, it is determined whether the detected temperature te is equal to or lower than the second predetermined temperature, in this case 0°C. If the detected temperature te of the evaporator temperature sensor 37 is equal to or lower than 0°C (Yes in step S12), the process proceeds to step S13, and the evaporator frost prevention operation continues. After this, the process from step S11 is repeated again. On the other hand, if the detected temperature te of the evaporator temperature sensor 37 exceeds the second predetermined temperature, in this case 0°C (No in step S12), the evaporator frost prevention operation is terminated in step S6, and normal drying operation control is performed in step S7.

According to this second embodiment, as in the first embodiment, the excellent effect of effectively preventing frost while preventing the drying time from becoming unnecessarily long can be obtained by performing the evaporator frost prevention operation. Furthermore, it is expected that there will be cases where performing the evaporator frost prevention operation for a certain time T0 is not sufficient to prevent frost, for example, when the room temperature tr is particularly low. If the detected temperature te of the evaporator temperature sensor 37 is lower than the second predetermined temperature even after the certain time T0 has elapsed, the evaporator frost prevention operation continues to be performed, so that frost and freezing of the evaporator 27 can be more reliably prevented.

The flowchart in FIG. 11 shows the third embodiment, and also shows the processing procedure executed by the control device 41 during drying operation. In this third embodiment, if the detected temperature te of the evaporator temperature sensor 37 is a high temperature exceeding a second predetermined temperature, for example 0°C, during the execution of the evaporator frost prevention operation, the control device 41 ends the evaporator frost prevention operation without waiting for the lapse of a certain period of time T0.

In other words, in the flow chart of FIG. 11, the drying operation is started in step S1, and the room temperature tr detected by the room temperature sensor 14 is read in step S2. In step S3, it is determined whether the detected room temperature tr is a low temperature, which is a first predetermined temperature (in this case, 5°C or lower), and if the room temperature tr detected by the room temperature sensor 14 is a low temperature of 5°C or lower (Yes in step S3), the evaporator frost prevention operation is performed in step S4. Then, in the next step S21, the temperature te of the inlet part of the evaporator 27 detected by the evaporator temperature sensor 37 is read.

In the next step S22, it is determined whether the detected temperature te of the evaporator temperature sensor 37 is equal to or lower than the second predetermined temperature (in this case, 0°C) or higher. If the detected temperature te is equal to or lower than 0°C (No in step S22), the process returns to step S4, and the evaporator frost prevention operation continues. In contrast, if the detected temperature te of the evaporator temperature sensor 37 exceeds the second predetermined temperature (in this case, 0°C) (Yes in step S22), the evaporator frost prevention operation ends in step S6, and normal drying operation control is performed in step S7.

According to this third embodiment, as in the first embodiment, the excellent effect of effectively preventing frost formation while suppressing the drying time from being unnecessarily long can be obtained by performing the evaporator frost prevention operation. Furthermore, when the temperature te of the inlet of the evaporator 27 detected by the evaporator temperature sensor 37 is low, there is a risk of frost formation, but when the temperature of the refrigerant flowing into the evaporator 27 becomes high, there is no risk. Therefore, by monitoring the temperature of the inlet of the evaporator 27 with the evaporator temperature sensor 37, the evaporator frost prevention operation can be promptly terminated when the second predetermined temperature is exceeded, and normal drying operation control can be proceeded to efficiently.

The specific values of the first and second predetermined temperatures, the fixed time, and the like disclosed in the above embodiments are merely examples and can be modified as appropriate. In addition, the above embodiments use a so-called multi-flow type evaporator and condenser, but a so-called fin-tube type heat exchanger may also be used. The present invention can also be applied to a clothes dryer that does not have a washing function and is only used for drying. The overall configuration of the heat pump, for example the configuration of the circulating air passage, may be configured so that the heat pump duct is located at the top inside the outer box.

The above embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The present embodiments and their modifications are within the scope and gist of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims.

In the drawings, 1 is a washer/dryer (clothes dryer), 2 is an outer box (main body), 4 is a drum, 9 is an exhaust opening, 10 is an exhaust damper, 11 is a damper motor, 14 is a room temperature sensor, 15 is a heat pump, 16 is a blower fan (blower device), 17 is an exhaust port, 18 is an air intake port, 20 is a circulation air path, 23 is an outside air intake port, 24 is a heat pump duct, 25 is an air intake duct, 27 is an evaporator, 28 is a condenser, 29 is a compressor, 37 is an evaporator temperature sensor, and 41 is a control device.

Claims (4)

A drum provided within the main body for storing clothes;
a circulation air passage provided outside the drum so as to communicate between an exhaust port for discharging air from the drum and an air intake port for blowing air into the drum;
a blower that circulates the air in the drum through the air circulation path;
A heat pump duct that is connected to an exhaust duct that is connected to the exhaust port and that constitutes a part of the circulation air passage;
a heat pump including a compressor and an evaporator and a condenser disposed within the heat pump duct;
an exhaust opening provided in the exhaust duct for exhausting air in the circulating air passage to the outside;
an exhaust damper that opens and closes the exhaust opening;
An outside air intake port is provided between the evaporator and the condenser of the heat pump duct;
A room temperature sensor for detecting an ambient temperature outside the heat pump;
an evaporator temperature sensor for detecting a temperature at an inlet of the evaporator;
A control device that controls each of the mechanisms to perform a drying operation,
The control device performs an evaporator frost prevention operation by changing the exhaust damper from a closed state to an open state and discharging air from the exhaust opening when the detected temperature of the room temperature sensor is a low temperature equal to or lower than a first predetermined temperature at the start of a drying operation, and terminates the evaporator frost prevention operation when the detected temperature of the evaporator temperature sensor is higher than a second predetermined temperature which is lower than the first predetermined temperature during the execution of the evaporator frost prevention operation. The clothes dryer according to claim 1, wherein the control device executes the evaporator frost prevention operation for a certain period of time from the start of the drying operation. The clothes dryer according to claim 1 or 2, wherein the control device executes the evaporator frost prevention operation when the temperature detected by the room temperature sensor is 5°C or lower at the start of the drying operation. The clothes dryer according to any one of claims 1 to 3, wherein the control device continues to perform the evaporator frost prevention operation if the temperature detected by the evaporator temperature sensor is a low temperature equal to or lower than the second predetermined temperature after the evaporator frost prevention operation has been performed for a certain period of time.

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