EP2792785A1

EP2792785A1 - Clothes dryer

Info

Publication number: EP2792785A1
Application number: EP12857227.8A
Authority: EP
Inventors: Hajime Nojima; Shinichi Matsuda; Takashi Komatsu
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2011-12-13
Filing date: 2012-02-23
Publication date: 2014-10-22
Anticipated expiration: 2032-02-23
Also published as: WO2013088585A1; CN103958765A; EP2792785B1; CN103958765B; EP2792785A4; JP2013123443A

Abstract

A clothes dryer according to the present invention includes a temperature detecting unit to detect the temperature of its refrigerant, and a controller to control a compressor and the like. The controller compares the temperature detected by the temperature detecting unit with a predetermined temperature so as to make a judgment of the necessity of refrigerant heating. When the temperature detected by the temperature detecting unit is lower than the predetermined temperature, the controller performs the refrigerant heating by energizing windings of a motor inside the compressor, without causing the motor to rotate. With this configuration, even when outside-air temperature decreases during a stop of operation of the clothes dryer, the refrigerant heating can prevent the occurrence of a liquid-back phenomenon, which allows the clothes dryer capable of preventing excessive loads on the compressor.

Description

TECHNICAL FIELD

The present invention relates to clothes dryers for drying clothes by supplying warm air into their rotary drums.

BACKGROUND ART

FIG. 5 is a longitudinal sectional view of a conventional clothes dryer. The conventional clothes dryers have had such a configuration as shown in FIG. 5 (see Patent Literature 1, for example). Moreover, some of washing-drying machines, which each integrate a washing machine and a drying machine into one body, can save drying time by preheating their compressors during washing operation (see Patent Literature 2, for example).
As shown in FIG. 5, the clothes dryer described in Patent Literature 1 is such that rotary drum 3, which rotates about horizontal shaft 2 as a center axis, is disposed inside outer case 1. Clothes input port 4 formed in the front of rotary drum 3 opens onto the front of outer case 1, and is openable and closeable by door 5. In the inside of outer case 1, circulating air passage 7 is configured including drying chamber 6 that is disposed in the inside of rotary drum 3. Circulating air passage 7 is equipped with drying chamber 6, air blowing chamber 8, heat exchange chamber 9, and the like, in the middle of the passage. Air in drying chamber 6 flows, through discharge port 10 in the rotary drum 3 side of the back wall of the drying chamber, into air blowing chamber 8. Then, the air circulates, through heat exchange chamber 9 and air outlet 11 disposed in the front of drying chamber 6, into drying chamber 6 again.
In air blowing chamber 8, fan 12 is disposed. In heat exchange chamber 9, heat absorber 13 and radiator 14 are disposed in the upstream and downstream sides, respectively. A heat pump device is configured including heat absorber 13, radiator 14, compressor 15, expansion mechanism 16 such as capillary tubes, and the like. High-humidity air from drying chamber 6 is cooled and dehumidified by heat absorber 13 to produce dry air. Then, the dry air reaches radiator 14 where it is heated to produce high-temperature air.
Moreover, part of the dry air flows out to the outside of the clothes dryer from air exhaust port 17, which thereby maintains the refrigerating cycle of the heat pump.
Then, the high-temperature air is supplied from air outlet 11 to drying chamber 6 to be used to dry clothes in the chamber. To the back wall of rotary drum 3 that forms a part of circulating-air passage 7, filter 18 is attached. Filter 18 collects lint separated from clothes 17. Arrow A indicates the direction of air flow. Rotation of motor 19 is transferred to rotary drum 3 and fan 12, via belts 20 and 21.
Moreover, electrode 22 is in contact with clothes 23 in rotary drum 3 during operation. Electrode 22 is configured with two of conductive members and an insulating member. Electrode 22 detects resistance between the conductive members, thereby sensing the degree of drying of the clothes.

Citation List

Patent Literatures

Patent Literature 1: Japanese Patent Unexamined Publication No. H07-178289
Patent Literature 2: Japanese Patent Unexamined Publication No. 2007-330674

SUMMARY OF THE INVENTION

A clothes dryer according to the present invention includes a heat pump device, a temperature detecting unit, a rotary drum, a blower fan, a heat exchange air passage, and a controller. The heat pump device is such that a pipeline connects a compressor, a radiator to radiate heat of a compressed refrigerant, a throttle part to reduce pressure of the high-pressure refrigerant, and a heat absorber to cause the reduced low-pressure refrigerant to deprive heat of its surroundings. The pipeline allows the refrigerant to circulate through it. The temperature detecting unit detects temperature of the refrigerant. The rotary drum forms a drying chamber which accommodates and dries clothes. The blower fan supplies warm air heated by the heat pump device, into the rotary drum. The heat exchange air passage passes the air for drying blown from the blower fan, through the heat absorber to the radiator, and then guides the air into the drying chamber. The controller controls the compressor and the like. When the temperature detected by the temperature detecting unit is lower than a predetermined temperature, the controller energizes the windings of a motor inside the compressor, without causing the motor to rotate.
With this configuration, even when outside-air temperature decreases during a stop of operation of the clothes dryer, it is possible to prevent the occurrence of a liquid back phenomenon, by energizing the windings of the motor inside the compressor without causing the motor to rotate. As a result, this allows the clothes dryer capable of preventing excessive loads on the compressor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view of a clothes dryer according to a first embodiment of the present invention.
FIG. 2 is a block diagram of the clothes dryer according to the first embodiment of the invention.
FIG. 3 is a schematic system diagram of the clothes dryer according to the first embodiment of the invention.
FIG. 4 is a perspective view of an electrode of the clothes dryer according to the first embodiment of the invention.
FIG. 5 is a longitudinal sectional view of a conventional clothes dryer.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note, however, that the embodiments to be described are in no way intended to limit the present invention.

(FIRST EXEMPLARY EMBODIMENT)

FIG. 1 is a longitudinal sectional view of a clothes dryer according to a first embodiment of the present invention. FIG. 2 is a block diagram of the clothes dryer according to the first embodiment of the invention. FIG. 3 is a schematic system diagram of the clothes dryer according to the first embodiment of the invention. FIG. 4 is a perspective view of an electrode of the clothes dryer according to the first embodiment of the invention.
In FIGS. 1 to 4, rotary drum 32 that accommodates and dries clothes 31 is rotatably disposed in the inside of clothes dryer body 33. Motor 34 drives rotary drum 32. Motor 34 drives rotary drum belt 35 to rotate rotary drum 32.
Motor 34 drives blower fan belt 36 to rotate blower fan 37. Air for drying is guided, via heat exchange air passage 38, into rotary drum 32 servicing as a drying chamber to accommodate clothes 31.
Electrode 39 (FIGS. 3 and 4) for detecting resistance of clothes 31 is disposed to face the inside of rotary drum 32 such that the electrode is in contact with clothes 31 inside rotary drum 32 during operation. Electrode 39 is configured with two of conductive members 40 and insulating member 41. Using electrode 39, resistance detecting unit 42 detects resistance between two conductive members 40, thereby detecting the resistance across clothes 31 which straddle and make contact with two conductive members 40.
Moreover, as shown in FIG. 2, heat pump device 43 is configured such that pipeline 48 connects compressor 44, radiator 45, throttle part 46, and heat absorber 47 so as for refrigerant to circulate through them. The refrigerant flows and circulates in the direction indicated by arrow B of FIG. 2, thereby forming a heat pump cycle. Radiator 45 radiates heat of the compressed refrigerant. Throttle part 46 is configured including a capillary tube and a throttle valve to reduce pressure of the high-pressure refrigerant. Heat absorber 47 is such that the reduced low-pressure refrigerant deprives heat of the surroundings. Temperature detecting unit 49 is disposed in the inside of heat exchange air passage 38. Controller 50 controls the rotation number of compressor 44 such that the temperature detected by temperature detecting unit 49 is approximately constant.
Next, operations of the clothes dryer will be described. First, using a door, clothes 31 to be dried are placed in the inside of rotary drum 32. Next, temperature detecting unit 49 detects temperature of the inside of heat exchange air passage 38. After a lapse of a certain period of time after stopping the operation (approximately 4 to 5 hours, depending on the situation of the surroundings), the temperature distribution in the inside of clothes dryer body 33 becomes approximately uniform. Therefore, the temperature detected in this state can be assumed to equal the temperature of the refrigerant inside pipeline 48. Controller 50 makes a judgment of refrigerant heating in which the temperature detected by temperature detecting unit 49 is compared with a predetermined temperature that is stored in advance. When the detected temperature is judged to be lower than the predetermined temperature, the controller advances the process to a refrigerant heating step, whereas if not so, the controller immediately advances the process to a drying step. Here, the predetermined temperature is set to be a low temperature at which the refrigerant becomes a liquid. That is, the predetermined temperature is of a threshold value at which a so-called liquid back phenomenon occurs where the liquefied refrigerant enters compressor 44.
In the drying step, motor 34 rotates both rotary drum 32 and blower fan 37, which thereby generates a flow (arrow A) of the air for drying. The air for drying deprives water of clothes 31 in rotary drum 32 to become high-humidity air. After that, the air is guided, through the inside of heat exchange air passage 38, into heat absorber 47 of heat pump device 43.
In heat absorber 47, the air for drying, the heat of which is deprived, is dehumidified. Then, the air is further transferred to radiator 45. In radiator 45, the air for drying is heated via heat radiation from the high-temperature refrigerant that has been heated by a sum of the amount of heat absorbed at heat absorber 47 and the amount of heat from compressor 44. Then, the air for drying is repeatedly circulated to the inside of rotary drum 32. In this way, clothes 31 become dried by repeating the above steps. When the temperature detected by temperature detecting unit 49 becomes close to the predetermined temperature, controller 50 controls compressor 44 such that the number of rotation of the compressor is decreased to keep the temperature of the air for drying constant.
In the refrigerant heating step, the clothes dryer performs the following operation. In a state where liquid back phenomenon occurs, if compressor 44 is driven to perform compression operation, compressor 44 is subjected to an excessive load. For this reason, in the refrigerant heating step, it is necessary to heat the refrigerant, without driving of compressor 44. Therefore, in the refrigerant heating step, the windings of the motor inside compressor 44 are energized without causing the motor to rotate. For example, a direct current is passed through two-phase windings of the three-phase windings of the motor inside compressor 44. With this configuration, the windings can generate heat due to resistance thereof, without causing the motor to rotate, which allows the heating of the refrigerant. As a result, the refrigerant is heated to change from liquid to gas.
Note, however, that the two-phase windings for passing the direct current are appropriately switch-selectable among those of three-phases, in order to hold the symmetry of the three-phase windings when driving compressor 44. The windings are configured with metal including copper or aluminum. The metal has characteristics that its resistance varies depending on temperature. This causes a problem that, if the temperatures of the windings are different from each other, the same applied voltage results in different currents among them. As a result, when driving the compressor 44, there is a possibility of the occurrence of nonuniform torque and/or noise of the motor inside the compressor. The appropriate switch-selection of the two-phase windings for passing the current allows their temperature-rises to be equivalent among the three-phase windings, which thereby prevents the problem of nonuniform torque and noise.
Here, a predetermined time period is determined in advance which equals the period of time required for heating the refrigerant. This required time period is obtained from an amount of heat needed for the refrigerant to change from liquid to gas. When the time measured by time measuring unit 51 becomes longer than the predetermined time period, controller 50 terminates the refrigerant heating step and advances the process to the drying step.
Note that, the lower the temperature of the liquid refrigerant is, the larger the amount of heat needed for the refrigerant to change into gas is. For this reason, controller 50 modifies the predetermined time period until time when the refrigerant heating is terminated, in accordance with a difference between the temperature detected by temperature detecting unit 49 and the threshold temperature of occurrence of the liquid back phenomenon. That is, controller 50 lengthens the time period until the time when the refrigerant heating step is terminated, with increasing difference between the temperature detected by temperature detecting unit 49 and the threshold temperature of occurrence of the liquid back phenomenon. This operation allows more effective prevention of the adverse effects of the liquid back phenomenon.
Moreover, as a way to pass the direct current through the windings of the motor inside compressor 44, a method of passing a constant current is considered in which a direct-current power source converted by conversion unit 52 from an alternating-current power source is controlled by a PWM (Pulse Width Modulation) method to produce the constant current. That is, when a pulse output with a fixed pulse width is applied to the windings of the motor inside compressor 44, it is possible to pass the direct current through the windings without causing the motor to rotate. However, when the current is controlled by the method to fix the pulse width, variations in voltage of the direct-current power source lead to variations in voltage of the controlled current, which changes the amount of the direct current passing through the windings. The change in the amount of the direct current passing through the windings results in a change in the amount of the heating in the refrigerant heating step. In order to avoid this problem, direct-current voltage detecting unit 53 is disposed to detect the voltage of the direct-current power source. Controller 50 compares the detected voltage with a standard voltage (a second predetermined voltage) of the direct-current power source, measured in advance, so as to determine the difference between them. Then, in accordance with the difference, the controller modifies the time period until the time when the refrigerant heating step is terminated. This configuration allows the more effective prevention of the adverse effects of the liquid back phenomenon.
For example, when the voltage detected by direct-current voltage detecting unit 53 is lower than the second predetermined voltage and the difference between them is large, controller 50 may lengthen the time period until the time when the refrigerant heating step is terminated. In contrast, when the voltage detected by direct-current voltage detecting unit 53 is lower than the second predetermined voltage and the difference between them is small, the controller may shorten the time period until the time when the refrigerant heating step is terminated.
Note that, in the embodiment, the description has been made in which direct-current voltage detecting unit 53 is used to detect the voltage of the direct-current power source. However, instead of this, alternating-current voltage detecting unit 54 may be used to detect the voltage of the alternating-current power source that is inputted to a power supply circuit, which leads to the same advantages. That is, controller 50 compares the voltage detected by alternating-current voltage detecting unit 54 with a standard voltage (a first predetermined voltage) of the alternating-current power source, measured in advance, to determine the difference between them. Then, in accordance with the difference, the controller may modify the time period until the time when the refrigerant heating step is terminated. For example, when the voltage detected by alternating-current voltage detecting unit 54 is lower than the first predetermined voltage and the difference between them is large, controller 50 may lengthen the time period until the time when the refrigerant heating step is terminated. In contrast, when the voltage detected by alternating-current voltage detecting unit 54 is lower than the first predetermined voltage and the difference between them is small, the controller may shorten the time period until the time when the refrigerant heating step is terminated.
Moreover, in the PWM method, it is possible to adjust the amount of the direct current passing through the windings, by controlling the pulse width. That is, the amount of the direct current passing through the windings can be increased by increasing the pulse width, while the amount of the direct current passing through the windings can be decreased by decreasing the pulse width. Utilizing this, the amount of the current may be adjusted to larger either when the temperature of the refrigerant is low or when the voltage of the alternating-current power source or direct-current power source is low. In the inverse case, the amount of the current may be adjusted to smaller.
That is, controller 50 may adjust the pulse width in accordance with the difference between the temperature detected by temperature detecting unit 49 and the predetermined temperature. For example, controller 50 may increase the pulse width when the difference is large between the temperature detected by temperature detecting unit 49 and the predetermined temperature, and the controller may decrease the pulse width when the difference is small between the temperature detected by temperature detecting unit 49 and the predetermined temperature.
Furthermore, controller 50 may adjust the pulse width in accordance with a difference between the voltage detected by direct-current voltage detecting unit 53 and the second predetermined voltage. For example, controller 50 may increase the pulse width when the difference is large between the voltage detected by direct-current voltage detecting unit 53 and the second predetermined voltage, and the controller may decrease the pulse width when the difference is small between the voltage detected by direct-current voltage detecting unit 53 and the second predetermined voltage.
In addition, controller 50 may adjust the pulse width in accordance with a difference between the voltage detected by alternating-current voltage detecting unit 54 and the first predetermined voltage. For example, controller 50 may increase the pulse width when the difference is large between the voltage detected by alternating-current voltage detecting unit 54 and the first predetermined voltage, and the controller may decrease the pulse width when the difference is small between the voltage detected by alternating-current voltage detecting unit 54 and the first predetermined voltage.
With this configuration, it is possible to terminate the refrigerant heating step in the predetermined time period, regardless of the temperature of the refrigerant and the voltage variations of either the alternating-current power source or the direct-current power source.
Moreover, during performing the refrigerant heating step, the refrigerant is sometimes heated via external factors attributed to changing situations where an indoor heating appliance is started to operate, direct sunlight begins to shine, or the like. In this case, in addition to the heat generated by passing the direct current through the windings, heat coming in via the external factors contributes to the heating of the refrigerant, which allows the refrigerant to change into gas in a shorter time than the predetermined time period. For this reason, temperature detecting unit 49 detects the temperature even during performing the refrigerant heating step. Then, when the detected temperature exceeds the predetermined temperature, controller 50 may terminate the refrigerant heating step even if the predetermined time period has yet to lapse, and may advance the process to the drying step. This allows the time until the completion of drying to be shortened.
Moreover, in the embodiment, although the judgment whether or not to perform the refrigerant heating step relies on the temperature detected by temperature detecting unit 49 disposed in the inside of heat exchange air passage 38, the judgment may rely on a temperature detected by another temperature detecting unit disposed in any other location, as long as the temperature can hold a correlation with the temperature of the refrigerant. For example, the temperature may be used which is detected by a temperature detecting unit disposed to detect the temperature of the refrigerant piping or outside air.
Furthermore, in the embodiment, only the refrigerant heating in the refrigerant heating step has been described. However, in addition to this, a heating unit such as a heater may be disposed in the vicinity of compressor 44. The additional heating from the outside of compressor 44 allows a shorter time period of the refrigerant heating.
As described above, the clothes dryer according to the present invention includes the heat pump device, the temperature detecting unit, the rotary drum, the blower fan, the heat exchange air passage, and the controller. The heat pump device is such that the pipeline connects the compressor, the radiator to radiate the heat of the compressed refrigerant, the throttle part to reduce the pressure of the high-pressure refrigerant, and the heat absorber in which the reduced low-pressure refrigerant deprives heat of the surroundings. The pipeline allows the refrigerant to circulate through it. The temperature detecting unit detects the temperature of the refrigerant. The rotary drum forms the drying chamber to accommodate and dry clothes. The blower fan supplies warm air heated by the heat pump device to the inside of the rotary drum. The heat exchange air passage passes the air for drying, blown from the blower fan, through the heat absorber to the radiator, and then guides the air into the drying chamber. The controller controls the compressor and the like. When the temperature detected by the temperature detecting unit is lower than the predetermined temperature, the controller performs the refrigerant heating by energizing the windings of the motor inside the compressor, without causing the motor to rotate. With this configuration, even when outside-air temperature decreases during a stop of operation of the clothes dryer, it is possible to prevent the occurrence of the liquid back phenomenon in which the refrigerant, as is in liquid form, goes back to the compressor. This allows the prevention of excessive loads on the compressor, resulting in the increased reliability of the compressor.
Moreover, the clothes dryer according to the present invention further includes the time measuring unit. When the time measured by the time measuring unit becomes longer than the predetermined time period, the controller may terminate the refrigerant heating. This allows the simple configuration to control the refrigerant heating step.
Furthermore, in the clothes dryer according to the present invention, the controller may apply the pulse output with the fixed pulse width to the windings of the motor inside the compressor, which does not cause the motor to rotate. With this configuration, the power inputted to the motor can be controlled.
In addition, in the clothes dryer according to the present invention, the controller may modify the predetermined time period until the time when the refrigerant heating is terminated, in accordance with the difference between the temperature detected by the temperature detecting unit and the predetermined temperature. With this configuration, the power inputted to the motor in the refrigerant heating step can be appropriately controlled according to circumstances.
Moreover, the clothes dryer according to the present invention further includes the alternating-current voltage detecting unit that detects the voltage of the alternating-current power source inputted to the clothes dryer. In accordance with the difference between the voltage detected by the alternating-current voltage detecting unit and the first predetermined voltage, the controller may modify the predetermined time period until the time when the refrigerant heating is terminated. With this configuration, the power inputted to the motor in the refrigerant heating step can be appropriately controlled according to circumstances.
Furthermore, the clothes dryer according to the present invention further includes the conversion unit that converts the alternating-current power source inputted to the clothes dryer into the direct-current power source, and the direct-current voltage detecting unit that detects the voltage of the direct-current power source converted by the conversion unit. In accordance with the difference between the voltage detected by the direct-current voltage detecting unit and the second predetermined voltage, the controller may modify the predetermined time period until the time when the refrigerant heating is terminated. With this configuration, the power inputted to the motor in the refrigerant heating step can be appropriately controlled according to circumstances.
In addition, in the clothes dryer according to the present invention, the controller may apply the pulse output to the windings of the motor inside the compressor, which does not cause the motor to rotate, with the pulse output being adjusted by the pulse width modulation (PWM) method. With this configuration, the power inputted to the motor can be controlled.
Moreover, in the clothes dryer according to the present invention, the controller may adjust the pulse width of the pulse output, in accordance with the difference between the temperature detected by the temperature detecting unit and the predetermined temperature. With this configuration, the power inputted to the motor in the refrigerant heating step can be appropriately controlled according to circumstances.
Furthermore, the clothes dryer according to the present invention further includes the alternating-current voltage detecting unit that detects the voltage of the alternating-current power source inputted to the clothes dryer. The controller may adjust the pulse width, in accordance with the difference between the voltage detected by the alternating-current voltage detecting unit and the first predetermined voltage. With this configuration, the power inputted to the motor in the refrigerant heating step can be appropriately controlled according to circumstances.
In addition, the clothes dryer according to the present invention further includes the conversion unit that converts the alternating-current power source inputted to the clothes dryer into the direct-current power source, and includes the direct-current voltage detecting unit that detects the voltage of the direct-current power source converted by the conversion unit. The controller may adjust the pulse width, in accordance with the difference between the voltage detected by the direct-current voltage detecting unit and the second predetermined voltage. With this configuration, the power inputted to the motor in the refrigerant heating step can be appropriately controlled according to circumstances.
Moreover, in the clothes dryer according to the present invention, the motor is one which has the three-phase windings. The controller may energize any two-phase windings of the three-phase windings. With this configuration, it is possible to heat the refrigerant by energizing the windings of the motor inside the compressor, without causing the motor to rotate.
Furthermore, in the clothes dryer according to the present invention, the controller may appropriately perform the switch-selection of the two-phase windings to be energized. With this configuration, their temperature rises of the three-phase windings can be made equal among them, thereby preventing the problem of nonuniform torque and noise.
In addition, in the clothes dryer according to the present invention, the controller may terminate the refrigerant heating when the temperature detected by temperature detecting unit exceeds the predetermined temperature during performing the refrigerant heating. With this configuration, it is possible to early terminate the refrigerant heating step when the refrigerant is warmed in a shorter period, which leads to the shorter operation time.
Moreover, in the clothes dryer according to the present invention, before the first starting of the compressor after power on, the controller may make the judgment of the refrigerant heating (whether or not it is necessary to energize the motor inside the compressor without causing the motor to rotate) and may perform the refrigerant heating. With this configuration, it is possible to reliably prevent the compressor from being driven in a liquid back state, which allows the increased reliability of the compressor.

INDUSTRIAL APPLICABILITY

As described above, the clothes dryer according to the present invention is capable of heating its refrigerant when the temperature of the refrigerant is low, so as to prevent the occurrence of a liquid back phenomenon. Consequently, beneficial applications of the invention can be developed for equipment in which a heat pump device is used for heating and/or drying.

REFERENCE MARKS IN THE DRAWINGS

32: rotary drum
37: blower fan
38: heat exchange air passage
43: heat pump device
44: compressor
45: radiator
46: throttle part
47: heat absorber
48: pipeline
49: temperature detecting unit
50: controller
51: time measuring unit
52: conversion unit
53: direct-current voltage detecting unit
54: alternating-current voltage detecting unit

Claims

A clothes dryer comprising:
a heat pump device including a pipeline connecting
a compressor,
a radiator for radiating heat of a refrigerant compressed,
a throttle part for reducing pressure of the refrigerant of high-pressure, and
a heat absorber for causing the reduced refrigerant of low-pressure to deprive heat of surroundings, the refrigerant circulating the pipeline;

a temperature detecting unit for detecting temperature of the refrigerant;

a rotary drum forming a drying chamber to accommodate and dry clothes;

a blower fan for supplying warm air heated by the heat pump device into the rotary drum;

a heat exchange air passage for passing the air for drying through the heat absorber to the radiator, and then for guiding the air into the drying chamber, the air being blown from the blower fan; and

a controller for controlling at least the compressor,
wherein, when the temperature detected by the temperature detecting unit is lower than a predetermined temperature, the controller energizes windings of a motor inside the compressor, without causing the motor to rotate.
The clothes dryer according to claim 1, further comprising a time measuring unit, wherein the controller terminates the energization when time measured by the time measuring unit becomes longer than a predetermined time period.
The clothes dryer according to claim 1 or 2, wherein the controller applies a pulse output having a fixed pulse width to the windings of the motor inside the compressor, without causing the motor to rotate.
The clothes dryer according to claim 2, wherein the controller modifies the predetermined time period until time when the energization is terminated, in accordance with a difference between the temperature detected by the temperature detecting unit and the predetermined temperature.
The clothes dryer according to claim 2, further comprising an alternating-current voltage detecting unit for detecting voltage of an alternating-current power source inputted to the dryer,
wherein the controller modifies the predetermined time period until time when the energization is terminated, in accordance with a difference between the voltage detected by the alternating-current voltage detecting unit and a first predetermined voltage.
The clothes dryer according to claim 2, further comprising:
a conversion unit for converting an alternating-current power source inputted to the dryer into a direct-current power source; and

a direct-current voltage detecting unit for detecting voltage of the direct-current power source converted by the conversion unit,

wherein the controller modifies the predetermined time period until time when the energization is terminated, in accordance with a difference between the voltage detected by the direct-current voltage detecting unit and a second predetermined voltage.
The clothes dryer according to claim 1 or 2, wherein the controller applies a pulse output to the windings of the motor inside the compressor, without causing the motor to rotate, the pulse output having a pulse width adjusted by a pulse width modulation (PWM) method.
The clothes dryer according to claim 7, wherein the controller adjusts the pulse width in accordance with a difference between the temperature detected by the temperature detecting unit and the predetermined temperature.
The clothes dryer according to claim 7, further comprising an alternating-current voltage detecting unit for detecting voltage of an alternating-current power source inputted to the dryer,
wherein the controller adjusts the pulse width in accordance with a difference between the voltage detected by the alternating-current voltage detecting unit and a first predetermined voltage.
The clothes dryer according to claim 7, further comprising:
a conversion unit for converting an alternating-current power source inputted to the dryer into a direct-current power source; and

a direct-current voltage detecting unit for detecting voltage of the direct-current power source converted by the conversion unit,

wherein the controller adjusts the pulse width in accordance with a difference between the voltage detected by the direct-current voltage detecting unit and a second predetermined voltage.
The clothes dryer according to claim 1 or 2, wherein the motor has three-phase windings, and the controller energizes any two-phase windings of the three-phase windings.
The clothes dryer according to claim 11, wherein the controller appropriately performs switch-selection of the two-phase windings to be energized.
The clothes dryer according to claim 1, wherein the controller terminates the energization when the temperature detected by the temperature detecting unit exceeds the predetermined temperature, during performing the energization.
The clothes dryer according to claim 1, wherein the controller makes a judgment of necessity of the energization and performs the energization, before first starting of the compressor after power on.
The clothes dryer according to claim 1, further comprising a heating unit in a vicinity of the compressor.