JP2009034409A - Clothes dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent frosting in a heat sink of a clothes dryer having a heat pump, to prevent liquid compression in a compression means, and to reduce drying time and power consumption. <P>SOLUTION: The clothes dryer has a bypass circulation airflow channel 26 where air circulates bypassing a drying chamber 5, a bypass switching means 27 for switching between a normal circulation airflow channel 18 and the bypass circulation airflow channel 26, and a control means 37 for controlling the bypass switching means 27. The bypass switching means 27 performs switching so that the bypass circulation airflow channel 26 is effective under conditions where frosting may occur and that air circulates through the bypass circulation airflow channel 26 bypassing the drying chamber 5 so as to rapidly increase temperature of the circulating air. Thereafter, switching is performed again so that the normal circulation airflow channel 18 is effective so as to prevent frosting. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a clothes dryer for drying clothes using a heat pump cycle.

  A conventional drum-type clothes dryer has a structure as shown in FIG. Hereinafter, the configuration will be described. As shown in FIG. 2, a rotating drum 52 that rotates about a horizontal axis as a central axis is arranged in the outer case 51, and the opening on the front surface of the rotating drum 52 is opened and closed by a door 53. An air passage 55 including a drying chamber 54 set inside the rotary drum 52 is formed in the outer case 51, and lint in the air that flows through the air passage 55 and the circulation fan 56 is removed. A lint filter 57 is provided. The heat absorber 58 and the radiator 59 installed in the air passage 55 and the compression means 60 and the decompression means 61 installed outside the air passage 55 constitute a heat pump cycle. A dehumidified water drainage passage 62 for draining dehumidified water dehumidified by the heat absorber 58 is provided.

In the above configuration, during the clothes drying process, the circulation fan 56 is operated, and the air is circulated through the air passage 55 so that the air flows in the order of the heat absorber 58, the radiator 59, and the drying chamber 54. Here, the compression means 60 is operated, and the high-humidity air flowing in from the drying chamber 54 is cooled and dehumidified by the heat absorber 58, and then the air is heated by the radiator 59, and the high-temperature and low-humidity air is returned to the drying chamber 54. Helps dry clothes. The dehumidified water is discharged out of the machine through the dehumidified water drain passage 62.
Japanese Patent No. 3330789

  However, in the conventional configuration, in the drying operation in winter, the temperature of the rotating drum 52, the air passage 55, and wet clothing before drying is low, and the temperature of the air flowing into the heat absorber 58 is low. It often happens that the evaporation temperature of the refrigerant becomes 0 ° C. or lower. Further, if the user neglects to clean the lint filter 57 for a long period of time, and if a large amount of lint adheres, the air volume is reduced and the evaporation temperature is greatly reduced. During the winter season or when the air volume is low, the heat absorber 58 is frosted, heat exchange in the heat absorber 58 is hindered and the refrigerant cannot sufficiently absorb heat, and the refrigerant does not completely evaporate and the heat absorber is mixed with liquid. Out of 58. And the liquid compression of the compression means 60 generate | occur | produced and there existed a subject that the compression means 60 might fail in a short time. Moreover, the temperature rise of the circulating air was slow, and there was a problem that the drying time was prolonged and the power consumption was increased.

  The present invention is intended to solve the problems of the conventional configuration, and prevents the heat absorber from frosting to prevent liquid compression in the compression means, and also shortens the drying time and reduces the consumption. The purpose is to realize electric power.

  In order to solve the above-described conventional problems, the clothes dryer of the present invention includes a bypass circulation air passage that bypasses the drying chamber and circulates air, and bypass switching means that switches between the normal circulation air passage and the bypass circulation air passage. And control means for controlling the bypass switching means.

  In conditions where there is a risk of frost formation by the heat absorber, the bypass switching means is switched so that the bypass circulation air passage becomes effective, the air is circulated through the bypass circulation air passage bypassing the drying chamber, and the temperature and heat dissipation of the circulation air After rapidly increasing the condensation temperature in the heat sink and the evaporation temperature in the heat absorber, the normal circulation air path is switched again to maintain the evaporation temperature in the heat absorber at 0 ° C or higher. It is possible to prevent the formation of frost on the surface.

  The clothes dryer of the present invention can prevent liquid compression by the compression means to prevent deterioration of the durability performance of the compression means, and can realize shortening of the drying time and low power consumption.

  The first invention includes a main body, a drying chamber that supports the main body and dries clothing, a heat pump unit that includes a compression means, a radiator, a decompression means, and a heat absorber, and a blowing means that circulates air. A normal circulation air passage through which air circulates through the heat pump unit and the drying chamber; a bypass circulation air passage through which air circulates bypassing the drying chamber; and a bypass that switches between the normal circulation air passage and the bypass circulation air passage. By providing the switching means and the control means for controlling the bypass switching means, under conditions where there is a risk of frost formation by the heat absorber, air is circulated through the bypass circulation air passage by bypassing the drying chamber. The temperature of the heat sink, the condensing temperature in the radiator and the evaporation temperature in the heat sink are rapidly increased, and then switched to the normal circulation air path side again, so that the evaporation temperature in the heat absorber becomes 0 ° C or lower. The occurrence of frost in heat absorber and maintain prevented while allowed to proceed drying step, the liquid compression prevents the compression means, the shortening of the drying time, can realize low power consumption.

  According to a second aspect of the invention, in particular, in the first aspect of the invention, there is provided an evaporating temperature detecting means for detecting the temperature of the refrigerant evaporating by the heat absorber, and the control means is provided for the evaporating temperature detecting means after the elapse of a predetermined time from the start of the drying process. If the detected temperature is equal to or lower than the frosting threshold, the frosting condition is determined and the airflow path is switched so that the bypass circulation airflow is valid. After a predetermined time elapses after switching or when the detection temperature exceeds the return threshold, the normal circulation airway By switching the air path so as to be effective, it can be determined with the highest accuracy whether or not the frosting condition is satisfied, and frosting in the heat absorber can be reliably prevented.

  According to a third aspect of the present invention, in the first aspect of the invention, the first aspect further includes a discharge temperature detection unit that detects a temperature of the refrigerant discharged from the compression unit, and the control unit includes a discharge temperature detection unit after a predetermined time has elapsed from the start of the drying process. If the detected temperature is equal to or lower than the frosting threshold, the frosting condition is determined and the airflow path is switched so that the bypass circulation airflow is valid. After a predetermined time elapses after switching or when the detection temperature exceeds the return threshold, the normal circulation airway By switching the air path so as to be effective, it is possible to accurately determine whether or not the frosting condition is satisfied, and frosting at the heat absorber can be prevented.

  According to a fourth aspect of the invention, in particular, in the first aspect of the invention, there is provided suction temperature detection means for detecting the temperature of the refrigerant sucked by the compression means, and the control means is provided for the suction temperature detection means after a predetermined time has elapsed from the start of the drying process. If the detected temperature is equal to or lower than the frosting threshold, the frosting condition is determined and the airflow path is switched so that the bypass circulation airflow is valid. After a predetermined time elapses after switching or when the detection temperature exceeds the return threshold, the normal circulation airway By switching the air path so as to be effective, it is possible to accurately determine whether or not the frosting condition is satisfied, and frosting at the heat absorber can be prevented.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the first aspect of the invention further comprises a condensation temperature detection means for detecting the temperature of the refrigerant condensed by the radiator, and the control means is provided for the condensation temperature detection means after a predetermined time has elapsed since the start of the drying process. If the detected temperature is equal to or lower than the frosting threshold, the frosting condition is determined and the airflow path is switched so that the bypass circulation airflow is valid. After a predetermined time elapses after switching or when the detection temperature exceeds the return threshold, the normal circulation airway By switching the air path so as to be effective, it is possible to accurately determine whether or not the frosting condition is satisfied, and frosting at the heat absorber can be prevented.

  In a sixth aspect of the invention, in particular, in the first aspect of the invention, there is provided inflow air temperature detection means for detecting the temperature of air flowing into the heat pump unit, and the control means detects the inflow air temperature after a predetermined time has elapsed from the start of the drying process. If the detected temperature of the means is below the frosting threshold, the frosting condition is judged and the airflow path is switched so that the bypass circulation airflow becomes effective. By switching the air path so that the air path becomes effective, it is possible to accurately determine whether or not the frosting condition is satisfied, and frost formation at the heat absorber can be prevented.

  In a seventh aspect of the invention, in particular, in the first aspect of the invention, there is provided an outflow air temperature detection means for detecting the temperature of the air flowing out from the heat pump unit, and the control means detects the outflow air temperature after a predetermined time has elapsed from the start of the drying process. If the detected temperature of the means is below the frosting threshold, the frosting condition is judged and the airflow path is switched so that the bypass circulation airflow becomes effective. By switching the air path so that the air path becomes effective, it is possible to accurately determine whether or not the frosting condition is satisfied, and frost formation at the heat absorber can be prevented.

  According to an eighth aspect of the invention, in particular, in the first aspect of the invention, there is provided ambient temperature detection means for detecting the temperature around the main body, and the control means reaches the detected temperature of the ambient temperature detection means after a predetermined time has elapsed since the start of the drying process. Accuracy is determined by determining the frost condition as being below the frost threshold and switching the air path so that the bypass circulation air path becomes effective, and switching the air path so that the normal circulation air path becomes effective after a lapse of a predetermined time after switching. Whether or not the frosting condition is satisfied can be determined well, and frosting at the heat absorber can be prevented.

  In particular, the ninth invention includes, in the first invention, evaporation temperature detection means for detecting the temperature of the refrigerant evaporated by the heat absorber, and suction temperature detection means for detecting the temperature of the refrigerant sucked by the compression means, The decompression means is configured to allow the amount of decompression to be adjusted, and by controlling the decompression means based on the difference between the detection temperature of the suction temperature detection means and the detection temperature of the evaporation temperature detection means, the suction superheat degree of the compression means is appropriately secured In addition, liquid compression by the compression means can be prevented more reliably.

  In a tenth aspect of the invention, in particular, in the first aspect of the invention, the discharge temperature detection means for detecting the temperature of the refrigerant discharged by the compression means, and the condensation temperature detection means for detecting the temperature of the refrigerant condensed by the radiator, The decompression unit is configured to allow the amount of decompression to be adjusted, and by controlling the decompression unit based on the difference between the detection temperature of the discharge temperature detection unit and the detection temperature of the condensation temperature detection unit, the discharge superheat degree of the compression unit is appropriately secured In addition, liquid compression by the compression means can be prevented more reliably.

  In an eleventh aspect of the invention, in particular, in the first to tenth aspects of the invention, since the pressure reducing means is an electric expansion valve, the degree of pressure reduction can be continuously varied, and the suction superheat degree of the compression means can be appropriately adjusted in a wide range of operating conditions. And the liquid compression of the compression means can be prevented more reliably.

  In the twelfth aspect of the invention, in particular, in any one of the first to eleventh aspects of the invention, the clothes stored in the drying chamber can be washed, so that the clothes are washed and dried in the same tank. Thus, a space-saving clothes washer / dryer can be provided in a single housing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is an overall cross-sectional view of a clothes dryer according to a first embodiment of the present invention.

  A cylindrical outer tub 2 is provided inside the main body 1, and a cylindrical inner tub 3 that accommodates clothes (not shown) is rotatably provided inside the outer tub 2, and is driven to rotate by a motor 4. Is done. The inner tub 3 becomes a clothes laundry room in the washing process, and becomes a clothes drying room 5 in the drying process. On the front surface of the main body 1, there are provided an opening 6 for putting clothes in and out and a door 7 for opening and closing the opening. A drain port 8 for discharging washing water and dehumidified water is provided in the lower part of the main body 1, and a drain valve 10 is provided in the washing water drain path 9. An air blowing means 11 for circulating air through the drying chamber 5 is provided, and a detachable lint filter 12 for removing foreign matters such as dust and lint in the air is provided.

  The compression means 13, the radiator 14, the electric expansion valve 15 that is a decompression means, and the heat absorber 16 are connected in a ring shape to form a heat pump unit 17, so that the heat absorber 16 is on the upstream side in the air flow direction. A radiator 14 and a heat absorber 16 are arranged. Further, there are provided a discharge temperature detection means 19 for detecting the temperature of the refrigerant discharged from the compression means 13 and a suction temperature detection means 20 for detecting the temperature of the refrigerant sucked by the compression means 13. Further, a condensing temperature detecting means 21 for detecting the temperature of the refrigerant condensed by the radiator 14 and an evaporating temperature detecting means 22 for detecting the temperature of the refrigerant evaporating by the heat absorber 16 are provided.

  The normal circulation air passage 18 between the drying chamber 5 and the heat absorber 16 is provided with an exhaust port 23 for exhausting a part of the circulating air and an inflow port 24 for the outside air to flow in. The inflow port 24 is provided with an outside air inflow control valve 25. Provided. The air flowing through the exhaust port 23 and the intake port 24 passes through the lint filter 12, and foreign matter is removed. In addition, a bypass circulation air passage 26 is provided in which air bypasses the drying chamber 5 and circulates through the heat absorber 16 and the radiator 14, and a bypass switching means 27 that switches between the normal circulation air passage 18 and the bypass circulation air passage 26 is provided. . Inflow air temperature detection means 28 for detecting the temperature of air flowing into the heat absorber 16 of the heat pump unit 17 and outflow air temperature detection means 29 for detecting the temperature of air flowing out of the radiator of the heat pump unit 17 are provided. An ambient temperature detecting means 30 for detecting the temperature around the main body 1 and a water temperature detecting means 31 for detecting the temperature of the washing water are provided at the lower part of the outer tub 2.

  A dehumidifying water container 32 for temporarily storing dehumidified water generated by the heat absorber 16 is provided below the heat absorber 16, and the water stored in the dehumidified water container 32 is connected to the drain outlet 8 by the operation of the drain pump 33. Then, it is discharged out of the main body 1. The dehumidified water drainage path 34 joins the washing water drainage path 9 downstream of the drain valve 10. A water level detecting means 35 for detecting the full water in the dehumidified water container 32 is provided.

  An operation means 36 is arranged on the upper front surface of the main body, and the operation of the operation means 36, the discharge temperature detection means 19, the suction temperature detection means 20, the condensation temperature detection means 21, the evaporation temperature detection means 22, and the inflow air temperature detection means. 28, the information of the outflow air temperature detection means 29, the ambient temperature detection means 30, the water temperature detection means 31, and the water level detection means 35 is input to the control means 37. The control means 37 is the motor 4, the drain valve 10, the blower means 11, the compression. The steps of washing, dehydration and drying are controlled by controlling the means 13, the electric expansion valve 15, the outside air inflow control valve 25, the bypass switching means 27, and the drainage pump 33.

  The operation and action of the above configuration will be described. In the washing process, the water supply valve (not shown) is opened with the drain valve 10 closed, and water is supplied into the outer tub 2 through the water supply path (not shown) until a predetermined water level is reached. The clothes are washed by rotating the inner tub 3 containing clothes and washing water. In the rinsing process after washing, water is supplied into the outer tub 2 as in the washing operation, and the inner tub 3 is rotated to rinse the clothes. In the dehydration step, the drain valve 10 is opened to drain water to the outside of the machine, and then the inner tub 3 containing clothes is rotated at high speed by the motor 4 to dehydrate.

  When the drying process is started, the outside air inflow control valve 25 is closed to operate the air blowing means 11, and the bypass switching means 27 is set at the solid line position in FIG. Air is circulated through the normal circulation air passage 18 as indicated by solid arrows in FIG. Further, the compression means 13 is operated, and the electric expansion valve 15 is set to a predetermined opening so that the heat pump cycle functions. The low-temperature and low-pressure gas-liquid mixed refrigerant in the heat absorber 16 evaporates by absorbing sensible heat and latent heat from the humid air coming out of the drying chamber 5 and becomes a low-pressure superheated gaseous refrigerant. The refrigerant sucked by the compressing means 13 is compressed to become a high-temperature and high-pressure gaseous refrigerant, dissipates heat into the air by the radiator 14 and condenses to become a high-pressure liquid refrigerant. Then, the pressure is reduced by the electric expansion valve 15 and flows into the heat absorber 16 again.

  The inner tub 3 is rotationally driven by the motor 4 so that the clothes are stirred up and down, deprived of moisture when the circulating air passes through the gaps of the clothes, exits the outer tub 2 in a humid state and flows through the normal circulation air passage 18. The air is sucked by the blowing means 11 and supplied to the heat absorber 16. In the heat absorber 16, the air is cooled and condensed, and dehumidified from the air. This air is heated in the radiator 14 to become hot air of high temperature and low humidity, flows through the normal circulation air passage 18 and flows into the inner tub 3 again, and promotes drying of the clothes.

  The dehumidified water generated in the heat absorber 16 is stored in the dehumidified water container 32, and when it is detected that the water level detecting means 35 has reached a predetermined water level, the drain pump 33 is operated for a predetermined time and discharged outside the main body 1. Waste thread is mixed in the circulating air that has passed through the drying chamber 5, but is captured by the lint filter 12. By the above operation, the clothing is dried.

  Here, if the user neglects to clean the lint filter 12 for a long period of time, the air volume of the circulating air decreases. In such a low air volume or in the winter drying process, the evaporation temperature of the refrigerant in the heat absorber 16 is lowered, and the heat absorber 16 may be frosted. In order to prevent this, the control means 37 determines that the detected temperature of the evaporation temperature detecting means 22 after the elapse of a predetermined time (for example, 5 minutes) from the start of the drying process is equal to or lower than the frosting threshold (for example, 0 ° C.). The bypass switching means 27 is switched to the position of the broken line in FIG. 1 so that the bypass circulation air path 26 becomes effective, and the bypass circulation air path 26, the heat absorber 16, and the heat radiation as indicated by the broken line arrow in FIG. 1. Air is circulated through the vessel 14. Since the air flowing out from the radiator 14 bypasses the drying chamber 5, the temperature of the circulating air rises quickly and flows into the heat absorber 16 without taking heat away from the clothes in the drying chamber 5. Condensation temperature and evaporation temperature also rise quickly.

  After switching to enable the bypass circulation air passage 26, the normal circulation air passage 18 side becomes effective after a predetermined time (for example, 20 minutes) has elapsed or when the temperature detected by the evaporation temperature detection means 22 exceeds the return threshold (for example, 10 ° C.). The bypass switching means 27 is switched again so that Since the temperature of the circulating air, the condensing temperature, and the evaporation temperature are sufficiently high, the evaporating temperature does not become 0 ° C. or less even when flowing through the cooled drying chamber 5, and the frost formation in the heat absorber 16 is not caused. Is prevented.

  When the temperature of the circulating air, the condensing temperature, and the evaporating temperature rise further and the condensing temperature detected by the condensing temperature detecting means 21 reaches a predetermined temperature, the outside air inflow control valve 25 is opened and a part of the circulating air is exhausted to the exhaust port. By exhausting air from the inlet 23 and sucking outside air from the inlet 24, the enthalpy corresponding to the input to the compressor 13 is radiated from the circulating air, and the compressor 13 is operated safely without causing an excessive increase in the condensation pressure. it can. And the ability of the compression means 13 is feedback-controlled by the detection temperature of the condensation temperature detection means 21, and the condensation temperature is maintained at a predetermined temperature. Further, the opening degree of the electric expansion valve 15 is controlled so that the difference between the detection temperature of the suction temperature detection means 20 and the detection temperature of the evaporation temperature detection means 22, that is, the suction superheat degree becomes a predetermined value, and the liquid compression of the compression means 13 is performed. To prevent. And the inflow air temperature detection means 28 detects the temperature of the circulating air which passed the drying chamber 5, and drying will be complete | finished when detection temperature reaches predetermined temperature (for example, 60 degreeC).

  As described above, under the condition that the heat absorber 16 may form frost, the bypass switching means 27 is switched so that the bypass circulation air passage 27 is effective, and the drying chamber 5 is bypassed to circulate the air and circulate. After the air temperature, the condensation temperature in the radiator 14 and the evaporation temperature in the heat absorber 16 are rapidly increased, the normal circulation air path 18 is switched again so that the evaporation temperature in the heat absorber 16 is changed. Generation of frost on the heat absorber 16 can be prevented by maintaining the temperature at 0 ° C. or higher. And the liquid compression in the compression means 13 is prevented, the deterioration of the durability of the compression means 13 is prevented, and shortening of the drying time and low power consumption can be realized.

  Moreover, since it is determined using the detection temperature of the evaporating temperature detection means 22 whether it is frosting conditions, frosting conditions can be determined most reliably.

  Further, since the decompression means 15 is the electric expansion valve 15, the degree of decompression can be continuously changed, and the suction superheat degree of the compression means 13 can be appropriately secured in a wide range of operating conditions, and the liquid compression of the compression means 13 can be performed. It can be prevented more reliably.

  Further, the compression means 13 is controlled by controlling the opening degree of the electric expansion valve 15 so that the difference between the detection temperature of the suction temperature detection means 20 and the detection temperature of the evaporation temperature detection means 22, that is, the suction superheat degree becomes a predetermined value. Can be reliably prevented.

  In addition, since the clothes housed in the drying chamber 5 can be washed, the washing and drying of the clothes can be performed consistently in the same tank. Can be provided.

  In the above embodiment, the bypass circulation air passage 26 communicates with the downstream side of the lint filter 12 and is most effective in preventing the heat absorber 16 from frosting. Since the drying chamber 5 can be bypassed even if it communicates with the upstream side of the filter 12, frosting of the heat absorber 16 can be prevented if a large amount of lint does not adhere to the lint filter 12. Further, the bypass switching means 27 does not have to pass all the high-temperature and low-humidity hot air heated in the radiator 14 through either the normal circulation air passage 18 or the bypass circulation air passage 26. The bypass switching means 27 may be controlled so that the part passes through the bypass circulation air passage 26 and the remaining warm air passes through the normal circulation air passage 18.

  In the above embodiment, the method of determining the frosting condition based on the temperature detected by the evaporation temperature detecting means 22 and controlling the bypass switching means 27 has been described. The method for determining the frosting condition based on the evaporating temperature is the most accurate, but instead of the evaporating temperature, the discharge temperature detecting means 19, the suction temperature detecting means 20, the condensing temperature detecting means 21, the inflow air temperature detecting means 28, the outflow air temperature. Control can be performed in the same manner as in the above-described embodiment using the detection temperature of the detection means 29 or the ambient temperature detection means 30.

  In the above embodiment, the electric expansion valve 15 is the pressure reducing means. However, the pressure reducing means may be configured by a plurality of capillary tubes and a switching valve to vary the amount of pressure reduction.

  In the above embodiment, the opening degree of the electric expansion valve 15 is controlled so that the difference between the detection temperature of the suction temperature detection means 20 and the detection temperature of the evaporation temperature detection means 22, that is, the suction superheat degree becomes a predetermined value. However, the same control can be performed using the difference between the detected temperature of the discharge temperature detecting means 19 and the detected temperature of the condensing temperature detecting means 21, that is, the information of the discharge superheat degree.

  Although various controls are performed based on the detected temperatures of the condensation temperature detecting means 21 and the evaporation temperature detecting means 22, a condensing pressure detecting means and an evaporation pressure detecting means are provided, and various controls are performed based on these detected pressures. Can also be done.

  Each embodiment describes an example when the heat pump unit 17 is mounted on a clothes dryer with a washing function that automatically performs from washing to drying in the same tank. However, the present invention is not limited to this. However, the same effect can be obtained even with a clothes dryer that only performs drying.

  As described above, since the clothes dryer according to the present invention can prevent frost formation in the heat absorber even in the drying process in winter or at a low air volume, the present invention is applied to any clothes dryer using a heat pump. it can.

Whole sectional view of a clothes dryer showing Embodiment 1 of the present invention Cross section of conventional clothes dryer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 5 Drying chamber 11 Blowing means 13 Compression means 14 Radiator 15 Electric expansion valve (pressure reduction means)
16 Heat absorber 17 Heat pump unit 18 Normal circulation air path 19 Discharge temperature detection means 20 Suction temperature detection means 21 Condensation temperature detection means 22 Evaporation temperature detection means 26 Bypass circulation air path 27 Bypass switching means 28 Inflow air temperature detection means 29 Outflow air temperature Detection means 30 Ambient temperature detection means 37 Control means

Claims (12)

A main body, a drying chamber supported in the main body for drying clothes, a heat pump unit comprising a compression means, a radiator, a decompression means and a heat absorber, a blower means for circulating air, the heat pump unit and the drying A normal circulation air passage through which air circulates through the chamber, a bypass circulation air passage through which air circulates by bypassing the drying chamber, bypass switching means for switching between the normal circulation air passage and the bypass circulation air passage, and the bypass A clothes dryer comprising control means for controlling the switching means. Evaporation temperature detection means for detecting the temperature of the refrigerant that evaporates in the heat absorber is provided, and the control means has a frosting condition when the detected temperature of the evaporation temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than a frosting threshold. The air path is switched so that the bypass circulation air path becomes valid after determination, and the normal circulation air path is activated after a predetermined time elapses after switching or when the detected temperature exceeds the return threshold. Clothes dryer. The compression means includes a discharge temperature detection means for detecting the temperature of the refrigerant discharged, and the control means has a frosting condition when the detection temperature of the discharge temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than a frosting threshold. The air path is switched so that the bypass circulation air path becomes valid after determination, and the normal circulation air path is activated after a predetermined time elapses after switching or when the detected temperature exceeds the return threshold. Clothes dryer. The compression means includes suction temperature detection means for detecting the temperature of the refrigerant sucked, and the control means has a frosting condition when the detected temperature of the suction temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than a frosting threshold. The air path is switched so that the bypass circulation air path becomes valid after determination, and the normal circulation air path is activated after a predetermined time elapses after switching or when the detected temperature exceeds the return threshold. Clothes dryer. Condensation temperature detection means for detecting the temperature of the refrigerant condensed by the radiator is provided, and the control means is a frosting condition when the detection temperature of the condensation temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than a frosting threshold. The air path is switched so that the bypass circulation air path becomes valid after determination, and the normal circulation air path is activated after a predetermined time elapses after switching or when the detected temperature exceeds the return threshold. Clothes dryer. Inflow air temperature detection means for detecting the temperature of the air flowing into the heat pump unit is provided, and the control means forms frost when the detected temperature of the inflow air temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than a frost formation threshold. The air path is switched so that the bypass circulation air path becomes effective based on the condition, and the air path is switched so that the normal circulation air path becomes effective after a predetermined time elapses after switching or when the detected temperature exceeds the return threshold. The clothes dryer described. Outflow air temperature detection means for detecting the temperature of the air flowing out from the heat pump unit is provided, and the control means forms frost when the detection temperature of the outflow air temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than the frost formation threshold. The air path is switched so that the bypass circulation air path becomes effective based on the condition, and the air path is switched so that the normal circulation air path becomes effective after a predetermined time elapses after switching or when the detected temperature exceeds the return threshold. The clothes dryer described. Ambient temperature detection means for detecting the ambient temperature of the main body is provided, and the control means bypasses by determining that the detected temperature of the ambient temperature detection means after the elapse of a predetermined time from the start of the drying process is equal to or less than the frosting threshold, as a frosting condition. The clothes dryer according to claim 1, wherein the air path is switched so that the circulation air path becomes effective, and the air path is switched so that the normal circulation air path becomes effective after a lapse of a predetermined time after the switching. An evaporating temperature detecting means for detecting the temperature of the refrigerant evaporating in the heat absorber; and an intake temperature detecting means for detecting the temperature of the refrigerant sucked by the compressing means; The clothes dryer according to claim 1, wherein the pressure reducing means is controlled based on a difference between a temperature detected by the temperature detecting means and a temperature detected by the evaporation temperature detecting means. A discharge temperature detection means for detecting the temperature of the refrigerant discharged by the compression means; and a condensation temperature detection means for detecting the temperature of the refrigerant condensed by the radiator, wherein the pressure reduction means is configured so that the amount of pressure reduction can be adjusted, and the discharge The clothes dryer according to claim 1, wherein the pressure reducing means is controlled based on a difference between a temperature detected by the temperature detecting means and a temperature detected by the condensation temperature detecting means. The clothes dryer according to any one of claims 1 to 10, wherein the decompression means is an electric expansion valve. The clothes dryer according to any one of claims 1 to 11, wherein the clothes contained in the drying chamber can be washed.

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