Clothes dryer

Abstract

To provide a clothes dryer capable of improving drying efficiency while achieving dryness detection with high accuracy.SOLUTION: A clothes dryer includes: a storage tub which has an exhaust port and an air supply port, and in which clothes are stored; a circulation air passage for connecting the exhaust port and the air supply port and for circulating the air in the storage tub; a heating device for heating the air flowing in the circulation air passage, and for generating warm air; a temperature sensor for detecting the temperature of the air flowing in the circulation air passage; a humidity sensor for detecting the humidity of the air flowing in the circulation air passage; and a control part for determining the progress or completion of a drying step of drying the clothes in the storage tub by detecting the temperature and the humidity, and capable of executing the drying step by controlling the heating device. The control part transits from the current step to the next step in the case where one of the temperature and the humidity has reached its threshold value during the operation.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a clothes dryer. [Background technology]

[0002] Patent Document 1 discloses a dryness sensing device for an exhaust-type clothes dryer. The dryness sensing device includes an electrode sensor mounted inside the drum that senses the dryness of the clothes by changing its voltage value depending on the humidity of the clothes, a thermistor mounted on the drum outlet side that senses the temperature of the air discharged after drying the clothes, and control means that receives inputs of the electrode sensor and thermistor to determine the dryness of the clothes. By determining the dryness of the clothes using the electrode sensor and thermistor, the device is able to accurately sense the dryness of the clothes not only in the early and middle stages of drying but also in the final stage of drying, thereby improving drying efficiency and performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2004-517681 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional configurations, the operation of the dryer is controlled based on the dryness value sensed by the electrode sensor from the start of the laundry drying operation until the clothes in the drum reach a set dryness value. When the dryness value is equal to or greater than the set dryness value, the operation of the dryer is controlled based on the discharge air temperature sensed by the thermistor. However, when the dryness value is less than the set dryness value, the dryer's operation is controlled based on the dryness value sensed by the electrode sensor, making it difficult to accurately detect dryness, which can result in prolonged drying times. Prolonged drying times can result in wasted electricity and damage to the clothes. Therefore, there is room for improvement in terms of improving drying efficiency while achieving highly accurate dryness detection.

[0005] Therefore, a clothes dryer that can improve drying efficiency while achieving highly accurate dryness detection is provided. [Means for solving the problem]

[0006] The clothes dryer of the embodiment includes: The drying machine comprises a storage tub having an exhaust port and an air intake port for storing clothes; a circulation air duct connecting the exhaust port and the air intake port for circulating air inside the storage tub; a heating device for heating the air flowing through the circulation air duct to generate warm air; a temperature sensor for detecting the temperature of the air flowing through the circulation air duct; a humidity sensor for detecting the humidity of the air flowing through the circulation air duct; and a control unit for determining the progress or completion of a drying process for drying clothes in the storage tub by detecting the temperature and humidity and for controlling the heating device to carry out the drying process, wherein the control unit transitions from the current process to the next process when either the temperature or the humidity reaches its respective threshold during operation. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating a configuration of a clothes dryer according to a first embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of a clothes dryer according to a first embodiment. [Figure 3]1 is a block diagram showing the electrical configuration of a clothes dryer according to a first embodiment; [Figure 4] FIG. 10 is a diagram showing an example of changes in temperature and humidity over time in the circulating air duct during the drying process in the clothes dryer according to the first embodiment. [Figure 5] FIG. 10 is a diagram showing an example of a case where dryness detection is performed based on changes in the values ​​of the temperature sensor and the humidity sensor in the clothes dryer according to the first embodiment. [Figure 6] FIG. 10 is a diagram showing an example of a case where a determination is made regarding the end of a falling rate period based on changes in the values ​​of the temperature sensor and the humidity sensor in the clothes dryer according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of dryness detection when a time limit has elapsed in the initial process in the clothes dryer according to the second embodiment. [Figure 8] FIG. 11 is a diagram showing an example of dryness detection when the drying process is resumed after being temporarily stopped in the clothes dryer according to the third embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, clothes dryers according to a number of embodiments will be described with reference to the drawings. Note that substantially the same elements in the respective embodiments are designated by the same reference numerals, and descriptions thereof will be omitted.

[0009] (First embodiment) First, the first embodiment will be described with reference to FIGS. The clothes dryer 10 shown in FIG. 1 is a drum-type clothes dryer, for example, a horizontal-axis type in which the rotation axis of the rotary tub 14 is oriented horizontally, or an inclined-axis type inclined downward toward the rear. The clothes dryer 10 has, for example, a washing function and a drying function, and is capable of performing a washing and drying operation including the washing, rinsing, spin-drying, and drying processes. In addition to the washing and drying operation, the clothes dryer 10 can also perform a drying operation, which is an operation that only performs drying. The drying operation includes a drying process. Note that the clothes dryer 10 is not limited to a drum-type clothes dryer, but may also be a vertical-axis type clothes dryer in which the rotation axis of the rotary tub is oriented vertically. The clothes dryer can also be configured without a washing function.

[0010] Clothes dryer 10 includes outer case 11, door 12, water tub 13, rotating tub 14, motor 15, drainage mechanism 16, water supply mechanism 17, and drying mechanism 20. In Fig. 1, the side of the installation surface of clothes dryer 10, i.e., the vertically lower side, is referred to as the lower side of clothes dryer 10, and the opposite side of the installation surface, i.e., the vertically upper side, is referred to as the upper side of clothes dryer 10. The side of clothes dryer 10 seen from the user, i.e., the left side of the paper in Fig. 1, is referred to as the front side of clothes dryer 10, and the side opposite the user, i.e., the right side of the paper in Fig. 1, is referred to as the rear side of clothes dryer 10.

[0011] Outer box 11 is formed into a rectangular hollow box shape as a whole by combining metals such as stainless steel plates and resin materials, for example. Outer box 11 forms the outer shell of clothes dryer 10. Outer box 11 has a front opening 111 on the front side that connects the inside and outside of outer box 11. Door 12 is provided on the front side of outer box 11 and opens and closes front opening 111. With door 12 open, a user can put clothes in or take them out of rotatable tub 14 through front opening 111. Water tub 13 and rotatable tub 14 are both formed into a so-called bottomed cylindrical shape that is open on one axial side, i.e., the front side, and has a bottom on the other axial side, i.e., the rear side.

[0012] The water tub 13 is capable of storing water therein. The water tub 13 is provided within the outer casing 11 and is elastically supported by a suspension (not shown). As shown in FIGS. 1 and 2, the water tub 13 has an exhaust port 131 and an air inlet 132. The exhaust port 131 and the air inlet 132 connect the inside and outside of the water tub 13. The exhaust port 131 is for discharging air from the water tub 13. The exhaust port 131 is provided, for example, in a portion toward the front of the upper part of the water tub 13, located to the right of the center in the left-right direction of the water tub 13. The air inlet 132 is for supplying air into the water tub 13. The air inlet 132 is provided, for example, in the bottom of the water tub 13, slightly above the center in the up-down direction of the bottom.

[0013] Rotary tub 14 is rotatably disposed within water tub 13 and can accommodate clothes therein. Rotary tub 14, together with water tub 13, constitutes a storage tub that accommodates clothes and dries them during the drying process. Rotary tub 14 is driven to rotate by motor 15. Rotary tub 14 has multiple holes 141. The multiple holes 141 are formed over almost the entire circumferential surface of rotary tub 14 and function, for example, as ventilation holes for air to enter and exit during the drying process. Motor 15 is provided on the outside bottom of water tub 13. Although not shown in detail, motor 15 is, for example, a brushless direct drive motor with a variable rotation speed. Motor 15 is directly connected to rotary tub 14 without, for example, a transmission belt or rotation reduction mechanism, and functions to rotate rotary tub 14 relative to water tub 13. Motor shaft 151 of motor 15, the central axis of water tub 13, and the rotation axis of rotatable tub 14 are all overlapped with each other in a so-called concentric relationship.

[0014] Drain mechanism 16 has the function of draining water stored in water tub 13 to the outside of clothes dryer 10. As shown in FIGS. 1 and 2, drain mechanism 16 has drain valve 161 and drain hose 162. Drain valve 161 is configured to be electromagnetically openable and closable. One end of drain hose 162 is connected to drain valve 161, and the other end is drawn out to the outside of clothes dryer 10. When drain valve 161 is opened, water stored in water tub 13 is drained to the outside of clothes dryer 10 through drain hose 162. Drain valve 161 opens and closes a drain path for draining water stored in water tub 13 to the outside.

[0015] The water supply mechanism 17 has the function of supplying water supplied from an external water source such as a water mains into the water tub 13. As shown in FIG. 2 , the water supply mechanism 17 has a water supply valve 171 and a water injection case 172. The water supply valve 171 is configured to be electromagnetically openable and closable. The water supply valve 171 has the function of opening and closing the water supply path leading from the external water source to the water tub 13 via the water supply mechanism 17. The water injection case 172 is provided downstream of the water supply valve 171. The water injection case 172 has a treatment agent case (not shown). The treatment agent case is configured to be able to store, for example, the laundry treatment agent required for one washing run. When the treatment agent case stores a laundry treatment agent, the water supplied from the external water source that flows into the water injection case 172 and the laundry treatment agent are mixed in the water injection case 172 and then supplied into the water tub 13 and the spin tub 14.

[0016] Drying mechanism 20 has the function of supplying warm air into water tub 13. Drying mechanism 20 has a circulation air duct 30 and a heating device 40. Circulation air duct 30 is located outside water tub 13, with one end connected to exhaust port 131 and the other end connected to air inlet 132. Circulation air duct 30 connects exhaust port 131 and air inlet 132. Circulation air duct 30 circulates air within water tub 13 and rotating tub 14. Circulation air duct 30 takes in air from water tub 13 through exhaust port 131, generates warm air via heating device 40, and then supplies the warm air into water tub 13 through air inlet 132. In this case, with respect to the air flowing through circulation air duct 30, exhaust port 131 is located upstream and air inlet 132 is located downstream.

[0017] The circulating air passage 30 can be configured to include, for example, an exhaust duct 31, a filter device 32, a connection duct 33, a heat exchanger 34, and an air supply duct 35. The exhaust duct 31 is configured, for example, by a flexible bellows-shaped hose. One end of the exhaust duct 31 is connected to the exhaust port 131, and the other end is connected to the filter device 32. The exhaust duct 31 is a part that exhausts air from, for example, the aquarium 13.

[0018] The filter device 32 is provided on the circulation air duct 30 downstream of the exhaust port 131 and captures foreign matter such as lint and dust contained in the air flowing through the exhaust port 131 and within the circulation air duct 30. The filter device 32 can be configured to include a filter device main body 321 and a filter 322. The filter device main body 321 can be configured as a container-shaped member made of, for example, resin and with an open top. The opening provided on the top surface of the filter device main body 321 is opened and closed by a lid (not shown). The filter 322 is detachably provided inside the filter device main body 321. The filter 322 captures foreign matter contained in the air flowing within the circulation air duct 30. A user can clean the filter 322 by removing it from the filter device main body 321.

[0019] The connection duct 33 is a duct that connects the filter device 32 and the heat exchanger 34. The heat exchanger 34 is disposed, for example, on the rear side of the clothes dryer 10, near the bottom inside the outer casing 11. The heat exchanger 34 is provided midway along the circulating air duct 30. Air that is taken into the circulating air duct 30 from the water tub 13 and flows through the connection duct 33 is dehumidified and heated as it passes through the heat exchanger 34, becoming dry, warm air. The intake air duct 35 is a duct that connects the heat exchanger 34 and the air intake port 132 of the water tub 13. The intake air duct 35 is a part that supplies air into the water tub 13, for example.

[0020] The heating device 40 is configured, for example, by a heat pump mechanism, i.e., a refrigeration cycle. The heating device 40 is provided midway through the circulating air duct 30. The heating device 40 heats the air flowing through the circulating air duct 30 to generate hot air for drying the clothes in the rotating tub 14. The hot air is set to a temperature of, for example, approximately 60°C to 70°C. As shown in FIG. 2 , the heating device 40 includes an evaporator 41, a condenser 42, a compressor 43, and a throttle valve 44. The heating device 40 is connected in a circular arrangement, with the condenser 42, the throttle valve 44, and the evaporator 41 in this order, relative to the compressor 43, in the direction in which the refrigerant flows. In other words, the heating device 40 circulates the refrigerant through the compressor 43, the condenser 42, and the evaporator 41.

[0021] The evaporator 41 and the condenser 42 are provided within the heat exchange unit 34. The evaporator 41 cools and dehumidifies the air circulating through the circulation air duct 30. The condenser 42 heats the air flowing through the circulation air duct 30 to turn it into warm air. The compressor 43 is provided outside the heat exchange unit 34. The compressor 43 supplies refrigerant to the condenser 42 by pressure transfer. The throttle valve 44 reduces the pressure of the high-pressure liquid refrigerant so that it can evaporate easily. Note that the heating device 40 may be configured as a well-known heater-type mechanism instead of a heat pump mechanism.

[0022] Drying mechanism 20 also has air blower 45. Air blower 45 is configured, for example, as a sirocco fan and includes a fan motor 451. Fan motor 451 drives and rotates air blower 45. Air blower 45 is provided midway along circulating air duct 30 and has the function of supplying air dehumidified and heated by heating device 40 into water tub 13 through air inlet 132. In other words, air blower 45 sends air from circulating air duct 30 into water tub 13. As shown in FIG. 2, air blower 45 is provided, for example, between heat exchanger 34 and air intake duct 35.

[0023] As shown in FIGS. 1 to 3 , clothes dryer 10 further includes exhaust mechanism 50, exhaust temperature sensor 61, intake air temperature sensor 62, and humidity sensor 63. Exhaust mechanism 50 has opening 51 and exhaust damper 52. Opening 51 is provided midway through circulation air duct 30 and connects the inside of circulation air duct 30 to the outside. Opening 51 exhausts a portion of the air in circulation air duct 30 to the outside. As shown in FIG. 1 , outer casing 11 is provided with communication opening 112. Communication opening 112 is located in a portion of outer casing 11 corresponding to opening 51 and connects the inside of outer casing 11 to the outside. Air exhausted from opening 51 to the outside of circulation air duct 30 is exhausted to the outside of clothes dryer 10 through communication opening 112, as indicated by the black arrow in FIG. 1 .

[0024] Exhaust damper 52 has an actuator such as a motor or a solenoid, and is configured to be able to open and close opening 51 based on a control signal. When exhaust damper 52 is open, opening 51 is open, and when exhaust damper 52 is closed, opening 51 is closed. In other words, exhaust damper 52 has the function of switching between an open state in which opening 51 is open and some of the air in circulation air passage 30 is discharged through opening 51, and a closed state in which opening 51 is closed and some of the air in circulation air passage 30 is not discharged through opening 51.

[0025] The exhaust air temperature sensor 61 detects the temperature of the air flowing through the circulation air duct 30 before it is affected by the heat of the evaporator 41 and the condenser 42. In this case, the exhaust air temperature sensor 61 is located downstream of the filter device 32 and upstream of the evaporator 41 in the circulation air duct 30. The supply air temperature sensor 62 detects the temperature of the air flowing through the circulation air duct 30 that has been heated by the condenser 42. In this case, the supply air temperature sensor 62 is located downstream of the blower device 45 and upstream of the air intake port 132 in the circulation air duct 30. The exhaust air temperature sensor 61 and the supply air temperature sensor 62 function as temperature sensors.

[0026] The humidity sensor 63 detects the humidity of the air in the circulating air duct 30 before it is affected by the heat of the evaporator 41 and the condenser 42. Humidity refers to relative humidity (%), which is the ratio of the amount of water vapor in the air at a certain temperature to the amount of saturated water vapor at that temperature. The humidity sensor 63 is located downstream of the filter device 32 and upstream of the evaporator 41 in the circulating air duct 30. The humidity sensor 63 is located, for example, near the exhaust gas temperature sensor 61. By locating the humidity sensor 63 downstream of the filter device 32, it is possible to prevent foreign matter from accumulating on the humidity sensor 63.

[0027] As shown in FIG. 3 , the clothes dryer 10 also includes a control unit 70 and a memory unit 71. The motor 15, the drain valve 161, the water supply valve 171, the compressor 43, the fan motor 451, the exhaust damper 52, and the memory unit 71 are electrically connected to the control unit 70 and operate under the control of the control unit 70. The exhaust air temperature sensor 61, the intake air temperature sensor 62, and the humidity sensor 63 are electrically connected to the control unit 70 and transmit their respective detection results to the control unit 70. The control unit 70 is mainly composed of a microcomputer having a CPU and memory areas such as ROM, RAM, and rewritable flash memory. The control unit 70 controls the overall operation of the clothes dryer 10. The memory area of ​​the control unit 70 stores a control program for controlling the clothes dryer 10 to operate. Each process of the control unit 70 is realized by the CPU executing the control program.

[0028] The control unit 70 receives detection signals from the various sensors 61-63 and controls the operation of the motor 15, drain valve 161, water supply valve 171, compressor 43, fan motor 451, and exhaust damper 52 based on a control program to perform operation. The memory unit 71 is configured with well-known storage media such as a ROM, HDD, semiconductor memory, and magnetic disk, and stores various types of information. The memory unit 71 can be configured, for example, by a predetermined area set in the storage area of ​​the control unit 70.

[0029] The control unit 70 can execute, for example, a drying operation. The drying operation includes a drying process. Since these are well-known configurations, detailed description will be omitted. However, during the drying operation, the control unit 70 executes a weight detection process and a fabric quality detection process before the drying process. The drying process is a process of drying clothes by supplying warm air into the water tub 13 and the rotatable tub 14. When the control unit 70 executes the drying process, it controls the operation of the heating device 40 (in this case, the compressor 43 and the blower 45) based on detection signals from the exhaust air temperature sensor 61, the intake air temperature sensor 62, and the humidity sensor 63, to dry the clothes in the rotatable tub 14.

[0030] That is, the control unit 70 determines the progress or completion of the drying process based on one or both of the temperatures detected by the exhaust air temperature sensor 61 or the intake air temperature sensor 62, or the humidity detected by the humidity sensor 63, and controls the compressor 43, the blower 45, etc. to carry out the drying process. The control unit 70 also stores temperature information relating to the temperatures detected by the exhaust air temperature sensor 61 and the intake air temperature sensor 62 while the drying process is in progress in the memory unit 71. The control unit 70 also stores humidity information relating to the humidity detected by the humidity sensor 63 while the drying process is in progress in the memory unit 71.

[0031] As shown in Fig. 4, the drying process progresses through a heating period T1, a constant rate period T2, a decreasing rate period T3, and a blowing period T4 in this order. The graph indicated by reference symbol A1 in Fig. 4 shows the change over time in the measurement value of the exhaust air temperature sensor 61. The graph indicated by reference symbol A2 in Fig. 4 shows the change over time in the measurement value of the supply air temperature sensor 62. The graph indicated by reference symbol A3 in Fig. 4 etc. shows the change over time in the difference between the measurement value of the supply air temperature sensor 62 and the measurement value of the exhaust air temperature sensor 61. The graph indicated by reference symbol B1 in Fig. 4 etc. shows the change over time in the measurement value of the humidity sensor 63. To make the drawings easier to understand, the graphs indicated by reference symbols A1 and A2 in Fig. 4, which show the measurement values ​​of the exhaust air temperature sensor 61 and the supply air temperature sensor 62, are shown by dashed double-dashed lines.

[0032] The heating period T1 is a period during which the clothes in the rotatable tub 14 are warmed. The heating period T1 is a period during which the temperature and humidity in the rotatable tub 14 tend to increase after the compressor 43 and the air blower 45 are activated and the drying process is initiated. The heating period T1 corresponds to an initial process executed at the beginning of the drying process. The control unit 70 can determine that the heating period T1 has ended when the temperature reaches a maximum temperature tm, which is the maximum value of the difference B1 between the measurement values ​​of the supply air temperature sensor 62 and the measurement values ​​of the exhaust air temperature sensor 61. That is, the control unit 70 can acquire the maximum temperature tm during the heating period T1. When the control unit 70 acquires the maximum temperature tm, the control unit 70 stores the maximum temperature tm in the memory unit 71. The control unit 70 can also acquire the maximum humidity hm, which is the maximum value of the measurement value B1 of the humidity sensor 63, during the heating period T1. The maximum humidity hm tends to be detected earlier than the maximum temperature tm. When the maximum humidity hm is acquired, the control unit 70 stores the maximum humidity hm in the storage unit 71.

[0033] During the constant rate period T2, the surface temperature of the clothes in the rotatable tub 14 remains approximately constant due to a balance between the heat generated by the heater 40 and the heat lost due to evaporation of moisture from the clothes, and the moisture content of the clothes decreases in proportion to the elapsed time. The constant rate period T2 corresponds to the dryness detection process, which is performed after the initial process and detects the dryness of the clothes in the rotatable tub 14. During the constant rate period T2, the temperature detected by the supply air temperature sensor 62 remains constant. The humidity detected by the humidity sensor 63 during the constant rate period T2 is lower than the humidity detected by the humidity sensor 63 during the heating period T1, which is the initial stage of drying when the clothes contain a lot of moisture. Furthermore, during the constant rate period T2, the humidity detected by the humidity sensor 63 decreases as the clothes dry.

[0034] At the end of the constant rate period T2, a certain amount of moisture has evaporated from the clothes, and the clothes are relatively dry. The control unit 70 can determine the end of the constant rate period T2 based on the time elapsed since the start of the constant rate period T2. The control unit 70 can also determine the end of the constant rate period T2 based on both the temperatures detected by the exhaust air temperature sensor 61 and the intake air temperature sensor 62, or the humidity detected by the humidity sensor 63. In other words, the control unit 70 can perform dryness detection during the drying process based on both the temperatures detected by the exhaust air temperature sensor 61 and the intake air temperature sensor 62, or the humidity detected by the humidity sensor 63. Dryness detection means detecting the degree of dryness of the clothes, and it detects when the clothes are relatively dry, that is, when a certain amount of moisture has evaporated from the clothes.

[0035] 5(a), in dryness detection using both the temperatures detected by the exhaust air temperature sensor 61 and the supply air temperature sensor 62, the control unit 70 performs dryness detection, for example, when the temperature difference A3 between the temperature detected by the supply air temperature sensor 62 and the temperature detected by the exhaust air temperature sensor 61 gradually decreases from the maximum temperature tm and the decrease from the maximum temperature tm reaches a threshold value tt1 determined based on the maximum temperature tm.The control unit 70 can then determine that the constant rate period T2 has ended when the temperature difference between the temperature detected by the supply air temperature sensor 62 and the temperature detected by the exhaust air temperature sensor 61 decreases from the maximum temperature tm and the amount of decrease reaches the threshold value tt1.

[0036] On the other hand, in dryness detection using the humidity detected by the humidity sensor 63, as shown in Figure 5(a), the control unit 70 performs dryness detection when, for example, the humidity B1 detected by the humidity sensor 63 gradually decreases from the maximum humidity hm and the decrease from the maximum humidity hm reaches a threshold value ht1 determined based on the maximum humidity hm. In other words, the control unit 70 can determine that the constant rate period T2 has ended when the humidity detected by the humidity sensor 63 decreases from the maximum humidity hm and the amount of decrease reaches the threshold value ht1.

[0037] Thus, during the constant rate period T2, it is determined whether either the amount of decrease from the maximum temperature tm or the amount of decrease from the maximum humidity hm has reached the respective thresholds tt1 and ht1. The control unit 70 then determines whether the amount of change from the maximum temperature tm and the maximum humidity hm detected during the initial step has reached the thresholds tt1 and ht1, respectively, which are set corresponding to the amount of change. In this case, the maximum temperature tm and the maximum humidity hm correspond to the respective judgment reference values. Note that the judgment reference values ​​may be values ​​other than the maximum temperature tm and the maximum humidity hm. The control unit 70 detects dryness when either the threshold tt1 or ht1 has been reached, and transitions to finishing drying of the clothes in the rotating tub 14. In other words, the control unit 70 can determine that the constant rate period T2 has ended when either the threshold tt1 or ht1 has been reached. In the example of Figure 5(a), the time it takes for the detected humidity B1 to reach the threshold value ht1 is shorter than the time it takes for the temperature difference A3 between the temperature detected by the supply air temperature sensor 62 and the temperature detected by the exhaust air temperature sensor 61 to reach the threshold value tt1, so as shown in Figure 5(b), the end of the constant rate period T2 can be determined based on the detected humidity B1 reaching the threshold value ht1, and control can be performed to transition to the declining rate period T3. In this way, by controlling the drying process using either humidity or temperature preferentially, the time required to complete the drying process can be shortened, and the drying process can be carried out efficiently.

[0038] Decreasing rate period T3 is a period during which the surface temperature of the clothes in rotatable tub 14 begins to rise and the amount of moisture evaporated from the clothes begins to decrease. During decreasing rate period T3, the clothes are prevented from becoming over-dried and wrinkles are prevented from re-occurring. During decreasing rate period T3, the rotation speed, rotation time, and other rotational control of rotatable tub 14 are controlled differently from that during constant rate period T2 to ensure that the air reaches the damp parts of the clothes in rotatable tub 14 more easily. Decreasing rate period T3 corresponds to the finishing process. During decreasing rate period T3, the temperature difference between the temperature detected by intake air temperature sensor 62 and the temperature detected by exhaust air temperature sensor 61 and the humidity detected by humidity sensor 63 change more slowly than during constant rate period T2.

[0039] As shown in Figure 6(a), the control unit 70 determines that the decline rate period T3 has ended when the temperature difference between the temperatures detected by the supply air temperature sensor 62 and the exhaust air temperature sensor 61 decreases from the maximum temperature tm and the amount of decrease reaches a threshold value tt2. The control unit 70 also determines that the decline rate period T3 has ended when the humidity detected by the humidity sensor 63 decreases from the maximum humidity hm and the amount of decrease reaches a threshold value ht2. That is, during the decline rate period T3, it is determined whether either the amount of decrease from the maximum temperature tm or the amount of decrease from the maximum humidity hm has reached the respective threshold values ​​tt2 and ht2. The threshold values ​​tt2 and ht2 are set to values ​​greater than the threshold values ​​tt1 and ht1 in the constant rate period T2, which corresponds to the step preceding the decline rate period T3. In other words, the absolute value of the temperature difference between the temperature detected by the supply air temperature sensor 62 corresponding to the threshold value tt2 and the temperature detected by the exhaust air temperature sensor 61 and the absolute value of the humidity detected by the humidity sensor 63 corresponding to the threshold value ht2 are smaller than the absolute value of the temperature difference between the temperature detected by the supply air temperature sensor 62 corresponding to the threshold value tt1 and the temperature detected by the exhaust air temperature sensor 61 and the absolute value of the humidity detected by the humidity sensor 63 corresponding to the threshold value ht1.

[0040] The control unit 70 determines whether the temperature reaches thresholds tt2 and ht2, which correspond to the decrease from the maximum temperature tm and maximum humidity hm detected during the initial process. If either threshold tt1 or ht1 is reached, the control unit 70 determines that the fall rate period T3 has ended and transitions to control of the next process, the air blowing period T4. In the example of FIG. 6(a), the time it takes for the detected humidity B1 to reach threshold ht2 is shorter than the time it takes for the temperature difference A3 between the temperature detected by the supply air temperature sensor 62 and the temperature detected by the exhaust air temperature sensor 61 to reach threshold tt2. Therefore, as shown in FIG. 6(b), the end of the fall rate period T3 can be determined based on the detected humidity B1 reaching threshold ht2, and control can transition to the air blowing period T4. In this way, by controlling the drying process using either humidity or temperature as a priority, the time required to complete the drying process can be shortened, thereby enabling the drying process to be performed efficiently. The control unit 70 can determine the end of the fall rate period T3 based on the time elapsed since the transition to the fall rate period T3.

[0041] The air-blowing period T4 is a period during which the rotating tub 14 and the clothes therein are cooled. The air-blowing period T4 corresponds to an air-blowing process. During the air-blowing period T4, the control unit 70 operates the air blower 45 while stopping the compressor 43, opens the opening 51 of the exhaust damper 52, and discharges a portion of the air in the circulating air passage 30 through the opening 51, thereby cooling the rotating tub 14 and the clothes therein. During the air-blowing period T4, heating of the clothes in the rotating tub 14 is suppressed. That is, after a predetermined time has elapsed since the transition to the decreasing rate period T3, the control unit 70 determines that the transition from the decreasing rate period T3 to the air-blowing period T4 has occurred, and controls the heating device 40 to suppress heating of the clothes in the rotating tub 14. The control unit 70 can determine the end of the air-blowing period T4, for example, based on the time elapsed since the transition to the air-blowing period T4.

[0042] According to the embodiment described above, clothes dryer 10 includes water tub 13, rotatable tub 14, circulation air duct 30, heater 40, exhaust air temperature sensor 61, intake air temperature sensor 62, humidity sensor 63, and controller 70. Water tub 13 and rotatable tub 14 accommodate clothes. Water tub 13 has exhaust port 131 and intake air port 132. Circulation air duct 30 connects exhaust port 131 and intake air port 132 to circulate air within water tub 13 and rotatable tub 14. Heater 40 heats air flowing through circulation air duct 30 to generate warm air. Exhaust air temperature sensor 61 and intake air temperature sensor 62 detect the temperature of air flowing through circulation air duct 30. Humidity sensor 63 detects the humidity of air flowing through circulation air duct 30. The control unit 70 determines the progress or completion of the drying process for drying the clothes in the rotating tub 14 by detecting the temperature and humidity of the air flowing through the circulation air duct 30, and controls the heating device 40 to carry out the drying process. During operation, when either the temperature of the air in the circulation air duct 30 or the humidity of the air in the circulation air duct 30 reaches the respective threshold value tt1, tt2, ht1, ht2, the control unit 70 transitions from the current process to the next process based on which of the temperature and humidity of the air in the circulation air duct 30 reaches the threshold value tt1, tt2 or ht1, ht2 first.

[0043] This allows for prioritizing the drying process when both the temperature of the air in the air circulation duct 30 and the humidity of the air in the air circulation duct 30 are used to detect the temperature and humidity of the air in the air circulation duct 30. In this case, the progress of the drying process is controlled based on whichever threshold is reached first, thereby enabling the degree of dryness of the clothes to be accurately determined while shortening the drying time and reducing power consumption. This allows for highly accurate dryness detection while improving drying efficiency.

[0044] The threshold values ​​tt1, tt2, ht1, and ht2 are not limited to those using the amount of decrease from the maximum temperature tm or maximum humidity hm, but may be those using, for example, the absolute value of the temperature A1 detected by the exhaust temperature sensor 61, or the absolute value or gradient of the amount of change in humidity B1 detected by the humidity sensor 63. This also makes it possible to shorten the drying time and reduce power consumption.

[0045] The drying process also includes an initial process and a dryness detection process. The initial process is a process executed at the beginning of the drying process. The dryness detection process is a process for determining whether or not either the temperature of the air in the circulation air duct 30 or the humidity of the air in the circulation air duct 30 has reached the respective threshold values ​​tt1 and ht1. The control unit 70 then determines whether or not the respective threshold values ​​tt1 and ht1 have been reached, which are set in accordance with the amount of decrease from the maximum temperature tm and maximum humidity hm of the air in the circulation air duct 30, both of which are detected during the execution of the initial process.

[0046] This allows for highly accurate detection of dryness by determining the degree of dryness of the clothes based on the maximum values ​​tm and hm of the temperature and humidity in the circulating air duct 30 detected at the early stage of the drying process.

[0047] (Second embodiment) Next, a second embodiment will be described with reference to Fig. 7. In this second embodiment, the method of progressing the drying process differs from that of the first embodiment. In the first embodiment, the heating period T1 is determined to be complete when either the maximum temperature tm of the temperature difference between the temperature detected by the supply air temperature sensor 62 and the temperature detected by the exhaust air temperature sensor 61 or the maximum humidity hm of the humidity detected by the humidity sensor 63 is detected.

[0048] A delay in the transition from the heating period T1 to the constant rate period T2 affects the overall time required for the drying process. For this reason, if the weight or fabric quality of the clothes in the rotating tub 14 causes the detection of the maximum temperature tm and maximum humidity hm to be delayed, delaying the end of the heating period T1, this may result in an extension of the overall time required for the drying process.

[0049] Therefore, in this embodiment, as shown in FIG. 7, a time limit TL is set for the heating period T1 until the transition to the constant rate period T2. The time limit TL indicates the elapsed time from the start of the drying process. The control unit 70 determines that the heating period T1 has ended when the time limit TL has elapsed. If the time limit TL has elapsed before the control unit 70 determines that the maximum temperature tm or maximum humidity hm has been detected during the heating period T1, the control unit 70 forcibly transitions from the heating period T1 to the constant rate period T2 and continues detecting the maximum temperature tm or maximum humidity hm during the constant rate period T2. Note that FIG. 7 illustrates a case in which the end of the constant rate period T2 is determined based on whether the detected humidity B1 during the constant rate period T2 reaches the threshold value ht1, and the transition to the falling rate period T3 is initiated.

[0050] According to the second embodiment, the same effects as those of the first embodiment are achieved. Furthermore, if the time limit TL has elapsed without the maximum temperature tm or maximum humidity hm being acquired, the control is forcibly shifted from the heating period T1 to the constant rate period T2, thereby allowing the drying process to proceed efficiently without lengthening the drying time.

[0051] (Third embodiment) Next, a third embodiment will be described with reference to FIG. 8. In this third embodiment, the method of dryness detection during the constant rate period T2 differs from the above-described embodiments. Specifically, this third embodiment illustrates an example of dryness detection when the drying process is temporarily stopped, for example, due to a user pausing operation or temporary stop of the compressor 43. FIG. 8 shows the progression of the drying process when a temporary stop period Ta occurs during the constant rate period T2. The two-dot chain line graph indicated by symbol Aa in FIG. 8 shows the change over time in the difference between the measurement values ​​of the supply air temperature sensor 62 and the exhaust air temperature sensor 61 when there is no temporary stop. The two-dot chain line graph indicated by symbol Ba in FIG. 8 shows the change over time in the measurement value of the humidity sensor 63 when there is no temporary stop.

[0052] 8, when a temporary suspension period Ta occurs, a temporary decrease occurs in the difference A3 between the measurement values ​​of the supply air temperature sensor 62 and the measurement value B1 of the humidity sensor 63. After that, when operation resumes, the measurement values ​​A3 and B1 increase, and the trends of the measurement values ​​A3 and B1 return to their previous state depending on the dryness of the clothes. When the drying process is resumed after a temporary suspension, the humidity tends to return to the same state as when the suspension did not occur, compared to the temperature and humidity in the circulation air duct 30. This is thought to be due to the fact that the area around the air intake vent 312 is prone to cool down because only air stores heat.

[0053] Therefore, in this embodiment, when the drying process is resumed after being temporarily stopped, the control unit 70 determines whether the humidity of the air in the circulating air duct 30 has reached the threshold values ​​ht1 and ht2. In other words, when the drying process is resumed after being temporarily stopped, dryness detection using the temperature of the air in the circulating air duct 30 is not performed.

[0054] According to the third embodiment, in the drying process after restarting from a temporary stop, the drying process is carried out with priority given to humidity, thereby realizing more accurate and faster dryness detection.

[0055] (Other embodiments) Here, when the drying operation is performed multiple times in succession, the temperature of the air in the circulation air duct 30 is already high, and the frequency of the compressor 43 is set low to protect the compressor 43. As a result, the difference A3 between the measurement value of the supply air temperature sensor 62 and the measurement value of the exhaust air temperature sensor 61 is unlikely to occur, and the maximum temperature tm may be measured at a low value. In this case, it is difficult to expect the maximum temperature tm to decrease to the threshold values ​​tt1 and tt2, making it difficult to detect dryness using temperature.

[0056] Therefore, when the drying operation is performed multiple times in succession, the control unit 70 can prioritize determining whether the humidity of the air in the circulation air duct 30 has reached the threshold values ​​ht1 and ht2. In other words, when the drying operation is performed multiple times in succession, dryness detection using the temperature of the air in the circulation air duct 30 is not performed. This allows for more efficient and accurate dryness detection. Note that "performing the drying operation multiple times in succession" means that the drying operation is performed consecutively after the completion of the previously performed drying operation. In other words, when the drying operation is performed two or more times in succession, this corresponds to "performing the drying operation multiple times in succession."

[0057] The above embodiments can be combined with each other, and only the characteristic features of two or more embodiments can be extracted and combined. Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0058] 10... clothes dryer, 13... water tub (storage tub), 131... exhaust port, 132... air intake port, 14... rotating tub (storage tub), 30... circulating air duct, 40... heating device, 61... exhaust temperature sensor (temperature sensor), 62... intake air temperature sensor (temperature sensor), 63... humidity sensor, 70... control unit

Claims

1. a storage tub having an exhaust port and an air intake port and configured to store clothing; a circulation air passage that connects the exhaust port and the air intake port and circulates air within the storage tank; a heating device that heats the air flowing through the circulating air passage to generate hot air; a temperature sensor that detects the temperature of the air flowing through the circulating air passage; a humidity sensor that detects the humidity of the air flowing through the circulating air passage; a control unit that determines the progress or completion of a drying process for drying the clothes in the storage tub by detecting the temperature and the humidity, and controls the heating device to execute the drying process; the control unit transitions from a current process to a next process when either the temperature or the humidity reaches a respective threshold value during the operation. Clothes dryer.

2. the drying process includes an initial process that is executed at an initial stage of the drying process, and a dryness detection process that determines whether or not either the temperature or the humidity has reached the threshold value; the control unit determines whether or not the temperature and humidity detected during the initial step have reached the threshold values ​​set in correspondence with the amounts of change from their respective reference values. The clothes dryer according to claim 1.

3. The initial step has a time limit set for transition to the dryness detection step, the control unit transitions from the initial step to the dryness detection step if the time limit has elapsed before detecting the reference values ​​of the temperature and the humidity in the initial step, and continues detecting the reference values ​​of the temperature and the humidity in the dryness detection step. The clothes dryer according to claim 2.

4. When the drying process is resumed after being temporarily stopped, the control unit determines whether the humidity has reached the threshold value with priority. The clothes dryer according to claim 1.

5. When the drying operation is performed multiple times in succession, the control unit determines whether the humidity has reached the threshold value with priority. The clothes dryer according to claim 1.

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