Dryer

Abstract

This disclosure provides a dryer that can suppress the reduction in drying capacity due to frost formation on the cooler. [Solution] The dryer of this disclosure comprises: a drying chamber for containing the material to be dried; a first cooling chamber communicating with the drying chamber by a first intake port and a first outlet port, with a first cooler and a first heating element arranged between the first intake port and the first outlet port in order from the upstream side; a first cooling fan for circulating the air in the drying chamber through the first cooling chamber; a second cooling chamber communicating with the drying chamber by a second intake port and a second outlet port, with a second cooler and a second heating element arranged between the second intake port and the second outlet port in order from the upstream side; and a second cooling fan for circulating the air in the drying chamber through the second cooling chamber.

Description

Technical Field

[0001] The present disclosure relates to a dryer for drying objects to be dried such as food.

Background Art

[0002] Patent Document 1 discloses a dryer that dries an object to be dried placed on a tray accommodated in a drying chamber by circulating the air in the drying chamber through a cooler and a heater disposed in a space communicating with the drying chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a dryer capable of suppressing a decrease in drying ability due to frosting on a cooler.

Means for Solving the Problems

[0005] The dryer in the present disclosure includes a drying chamber for accommodating an object to be dried, a first cooling chamber that communicates with the drying chamber through a first suction port and a first blowout port, and in which a first cooler and a first heater are arranged in order from the upstream side between the first suction port and the first blowout port, a first cooling fan that circulates the air in the drying chamber through the first cooling chamber, a second cooling chamber that communicates with the drying chamber through a second suction port and a second blowout port, and in which a second cooler and a second heater are arranged in order from the upstream side between the second suction port and the second blowout port, and a second cooling fan that circulates the air in the drying chamber through the second cooling chamber.

Effects of the Invention

[0006] The dryer of this disclosure can suppress the reduction in drying capacity due to frost formation on the cooler. [Brief explanation of the drawing]

[0007] [Figure 1] Configuration diagram of the dryer in the embodiment [Figure 2] Perspective view of the side panel of the drying chamber in the embodiment. [Figure 3] Control block diagram of the dryer in the embodiment [Figure 4] Flowchart of the control process for drying operation in the embodiment [Figure 5] Timing chart of drying operation in the embodiment [Figure 6] Diagram illustrating the operating modes of the first drying mode and the second drying mode in the embodiment. [Figure 7] Diagram illustrating temperature control inside the drying chamber in the embodiment. [Figure 8] Diagram illustrating the method for determining the defrosting timing of the cooler in the embodiment. [Modes for carrying out the invention]

[0008] (Knowledge and other information that formed the basis of this disclosure) At the time the present inventors conceived of this disclosure, there was a technology for a dryer used to dry food and other items, in which the air in the drying chamber was circulated through a cooler and a heating element located in a space connected to the drying chamber, thereby drying the items placed on trays in the drying chamber. As a result, air that had been dehumidified by the cooler and then heated by the heating element circulated through the drying chamber, drying the items.

[0009] However, with the above technology, if the amount of water removed from the material being dried increases due to a large quantity of material, the amount of moisture in the circulating air increases, making it easier for frost to form on the fins of the cooler during heat exchange. This clogging between the fins due to frost reduces the drying capacity of the dryer and increases the drying time. While heating the cooler to defrost can be considered as a solution, if the defrosting frequency increases, the next defrosting operation may be performed before the humidity in the drying chamber has completely decreased after the previous defrosting, potentially resulting in drying being performed with reduced drying capacity. Therefore, this disclosure provides a dryer that can suppress the reduction in drying capacity due to frost formation on the cooler.

[0010] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The attached drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0011] (Embodiment) The embodiments will be described below with reference to Figures 1 to 7. [1. Dryer Configuration] Referring to Figure 1, the configuration of the dryer 1 in this embodiment will be described. Figure 1 schematically shows the configuration of the dryer 1 in a vertical cross-sectional view. The dryer 1 comprises a drying chamber 80 in which the material to be dried F is contained, a refrigeration cycle 50, a control unit 10, and an operating unit 2. The material to be dried F is, for example, food.

[0012] The drying chamber 80 includes six shelves 81 on which the object to be dried F is placed. A plurality of communication holes 81a that communicate the upper surface side and the lower surface side of the shelf 81 are provided on each shelf 81. A plurality of first stirring fans 82 and second stirring fans 83 for promoting the flow of air in the space partitioned by each shelf 81 are provided on the first side plate 90 and the second side plate 91 to which each shelf 81 is attached.

[0013] As shown in FIG. 2, for the first side plate 90 and the second side plate 91, an opening 92 is provided on the first side plate 90 to which the first stirring fan 82 is attached, and an opening 92 is provided on the second side plate 91 to which the second stirring fan 83 is attached. Further, the first side plate 90 and the second side plate 91 are provided with slits 93, 94 provided on the left and right sides of the opening 92, and slits 95, 96 provided on the left and right bent portions. By allowing air to flow through these slits 93, 94, 95, 96, the circulation of air in the drying chamber 80 is promoted.

[0014] The refrigeration cycle 50 disposed above the drying chamber 80 includes a compressor 52, a radiator 53, a three-way valve 54, a first expansion valve 55a, a first cooler 56a, a second expansion valve 55b, and a second cooler 56b connected by a refrigerant circuit 51. A first cooler temperature sensor 57a is provided near the inlet of the first cooler 56a, and a second cooler temperature sensor 57b is provided near the inlet of the second cooler 56b. A drying chamber temperature sensor 85 is provided near the central portion of the drying chamber 80. Note that a capillary tube may be used instead of the first expansion valve 55a and the second expansion valve 55b.

[0015] The three-way valve 54 switches the flow path of the refrigerant discharged from the compressor 52 and flowing through the radiator 53 to any one of the following three flow path patterns. First flow path pattern: The refrigerant is circulated to the first cooler 56a side, and the flow of the refrigerant to the second cooler 56b side is blocked. The first cooler 56a is in an operating state, and the second cooler 56b is in a stopped state. The second flow path pattern... causes the refrigerant to flow toward the second cooler 56b and blocks the flow of the refrigerant toward the first cooler 56a. The second cooler 56b becomes operative and the first cooler 56a becomes inoperative. The third flow path pattern... causes the refrigerant to flow toward both the first cooler 56a and the second cooler 56b. Both the first cooler 56a and the second cooler 56b become operative.

[0016] Near the first suction port 61a of the first cooling chamber 60a where the first cooler 56a is disposed, a first cooling fan 65a is provided, and near the first blowout port 62a, a first heater 66a is provided. The first cooling fan 65a circulates the air in the drying chamber 80 via the first cooling chamber 60a. By the operation of the first cooling fan 65a, the air sucked from the drying chamber 80 into the first suction port 61a is cooled and dehumidified by the first cooler 56a, then heated by the first heater 66a, and sent from the first blowout port 62a to the first flow path 70. The object to be dried F is dried by the air flowing from the first flow path 70 into the drying chamber 80 (the air dehumidified by the first cooler 56a and heated by the first heater 66a).

[0017] Similarly, near the second suction port 61b of the second cooling chamber 60b where the second cooler 56b is disposed, a second cooling fan 65b is provided, and near the second blowout port 62b, a second heater 66b is provided. The second cooling fan 65b circulates the air in the drying chamber 80 via the second cooling chamber 60b. By the operation of the second cooling fan 65b, the air sucked from the drying chamber 80 into the second suction port 61b is cooled and dehumidified by the second cooler 56b, then heated by the second heater 66b, and sent from the second blowout port 62b to the second flow path 71. The object to be dried F is dried by the air flowing from the second flow path 71 into the drying chamber 80 (the air dehumidified by the second cooler 56b and heated by the second heater 66b).

[0018] Below the first cooler 56a, a first defrost heater 67a is provided to heat the first cooler 56a and remove frost that has accumulated on it. Similarly, below the second cooler 56b, a second defrost heater 67b is provided to heat the second cooler 56b and remove frost that has accumulated on it.

[0019] Next, the control specifications of the dryer 1 will be described with reference to Figure 3. The control unit 10 is connected to the operation unit 2, compressor 52, three-way valve 54, first cooling fan 65a, second cooling fan 65b, first heating heater 66a, second heating heater 66b, first defrost heater 67a, second defrost heater 67b, first stirring fan 82, second stirring fan 83, drying chamber temperature sensor 85, first cooler temperature sensor 57a, and second cooler temperature sensor 57b. The operation unit 2 includes an operation switch for instructing the start and stop of the dryer 1, a drying target setting switch for setting the amount and type of material F to be dried, a display unit for displaying the operating status of the dryer 1, and the like.

[0020] The control unit 10 includes a processor 20, a memory 30, an interface circuit (not shown), and the like. The memory 30 stores a program 31 for controlling the dryer 1, operating condition data 32 for setting the operating conditions of the dryer 1 according to the setting operations of the operation unit 2, and the like. The processor 20 reads and executes the program 31 and functions as an operation control unit 21, a first frost level recognition unit 22, and a second frost level recognition unit 23.

[0021] The operation control unit 21 executes the drying operation of the dryer 1 according to the operating conditions determined by referring to the operating condition data 32 in response to the setting operation of the operation unit 2. Details of the drying operation will be described later. The first frost level recognition unit 22 recognizes the frost level of the first cooler 56a based on the temperature detected by the first cooler temperature sensor 57a while the first cooler 56a is operating.

[0022] Specifically, the first frost level recognition unit 22 recognizes, in accordance with the decrease in the temperature detected by the first cooler temperature sensor 57a, that the lower the temperature detected by the first cooler temperature sensor 57a, the higher the frost level of the first cooler 56a (the larger the amount of frost attached to the first cooler 56a, and the greater the thickness of the frost attached to the first cooler 56a). The decrease in the temperature detected by the first cooler temperature sensor 57a corresponds to the degree of temperature decrease of the detection temperature in this disclosure.

[0023] Similarly, the second frost level recognition unit 23 recognizes, while the second cooler 56b is operating, that the lower the temperature detected by the second cooler temperature sensor 57b, the higher the frost level of the second cooler 56b (the greater the amount of frost adhering to the second cooler 56b, or the greater the thickness of the frost adhering to the second cooler 56b). The decrease in the temperature detected by the second cooler temperature sensor 57b corresponds to the degree of temperature decrease of the detection temperature in this disclosure.

[0024] [2. Control of the drying operation] The control of the drying operation performed by the operation control unit 21 will be explained with reference to Figures 4 to 6. The operation control unit 21 performs the drying operation by switching between the following first drying mode operation and second drying mode operation according to the flowchart shown in Figure 4.

[0025] First drying mode operation: The operation control unit 21 sets the three-way valve 54 to the first flow path pattern (allowing the refrigerant discharged from the compressor 52 to flow to the first cooler 56a side and blocking the flow of refrigerant to the second cooler 56b side). The operation control unit 21 activates the first cooler 56a by operating the compressor 52, and also activates the first cooling fan 65a, the first heating heater 66a, the first stirring fan 82, and the second stirring fan 83. The operation control unit 21 also activates the second defrost heater 67b to defrost the second cooler 56b. The operation control unit 21 stops the operation of the second defrost heater 67b and ends the defrosting of the second cooler 56b when the temperature of the second cooler temperature sensor 57b reaches or exceeds a predetermined defrosting completion temperature, or when the operating time of the second defrost heater 67b reaches or exceeds a predetermined defrosting execution time.

[0026] Second drying mode operation: The operation control unit 21 sets the three-way valve 54 to the second flow path pattern (allowing the refrigerant discharged from the compressor 52 to flow to the second cooler 56b side and blocking the flow of refrigerant to the first cooler 56a side). The operation control unit 21 activates the second cooler 56b by operating the compressor 52, and also activates the second cooling fan 65b, the second heating heater 66b, the first stirring fan 82, and the second stirring fan 83. The operation control unit 21 also activates the first defrost heater 67a to defrost the first cooler 56a. The operation control unit 21 stops the operation of the first defrost heater 67a and ends the defrosting of the first cooler 56a when the temperature of the first cooler temperature sensor 57a reaches or exceeds a predetermined defrosting completion temperature, or when the operating time of the first defrost heater 67a reaches or exceeds a predetermined defrosting execution time.

[0027] The procedure for drying operation by the operation control unit 21 will be explained according to the flowchart shown in Figure 4. The operation control unit 21 starts the drying operation in response to the operation start operation by the operation unit 2. In step S1 of Figure 4, the operation control unit 21 starts the first drying mode operation. Note that when the first drying mode operation is performed for the first time, no frost has formed on the second cooler 56b, so the operation control unit 21 does not defrost the second cooler 56b to activate the second defrost heater 67b. In the subsequent loop processing of steps S2, S3, and S20, the operation control unit 21 recognizes the temperature detected by the first cooler temperature sensor 57a using the first frost level recognition unit 22 in step S2, determines in step S3 whether the temperature detected by the first cooler temperature sensor 57a is below the first frost determination temperature, and determines in step S20 whether the drying operation termination condition has been met.

[0028] The first frost determination temperature in step S3 corresponds to the first determination level in this disclosure. The drying operation termination conditions include the operation unit 2 stopping the drying operation, the operation time set by the operation unit 2 elapsed, etc. When the temperature detected by the first cooler temperature sensor 57a in step S3 falls below the first frost determination temperature, the operation control unit 21 proceeds to step S4. Also, when the drying operation termination conditions are met in step S20, the operation control unit 21 proceeds to step S21 to terminate the first drying mode operation, and then proceeds to step S32 to terminate the drying operation.

[0029] In step S4, the operation control unit 21 terminates the first drying mode operation. In the following step S5, the operation control unit 21 starts the second drying mode operation. In the loop processing of the next steps S6, S7, and S30, the operation control unit 21 recognizes the temperature detected by the second frost level recognition unit 23 of the second cooler temperature sensor 57b in step S6, determines in step S7 whether the temperature detected by the second cooler temperature sensor 57b is below the second frost determination temperature, and determines in step S30 whether the drying operation termination condition has been met. The second frost determination temperature in step S7 corresponds to the second determination level in this disclosure.

[0030] In step S7, when the temperature detected by the second cooler temperature sensor 57b falls below the second frost determination temperature, the operation control unit 21 proceeds to step S8. Also, in step S30, when the drying operation termination condition is met, the operation control unit 21 proceeds to step S31 to terminate the second drying mode operation, and then proceeds to step S32 to terminate the drying operation.

[0031] In step S8, the operation control unit 21 terminates the second drying mode operation. In the following step S9, the operation control unit 21 starts the first drying mode operation, proceeds to step S2, and executes the processes from step S2 onward again.

[0032] Figure 5 is a timing chart showing the timing of operation (ON) and stop (OFF) of the first cooler 56a, second cooler 56b, first cooling fan 65a, second cooling fan 65b, first heating heater 66a, second heating heater 66b, first stirring fan 82, second stirring fan 83, first defrost heater 67a, and second defrost heater 67b when the process shown in the flowchart in Figure 4 is executed, using a common time axis t.

[0033] In Figure 5, drying operation starts at t1, the first drying mode operation is performed between t1-t2 and t4-t6, and the second drying mode operation is performed between t2-t3 and t6-t8. Then, at t2 and t6, when the system switches from the first drying mode operation to the second drying mode operation, the first defrost heater 67a activates to remove frost accumulated on the first cooler 56a, and the first defrost heater 67a stops operating at t3 and t7. Also, at t4, when the system switches from the second drying mode operation to the first drying mode operation, the second defrost heater 67b activates to remove frost accumulated on the second cooler 56b, and the second defrost heater 67b stops operating at t5.

[0034] Figure 6 is an explanatory diagram showing the operation and shutdown states of the first cooler 56a and the second cooler 56b, and the direction of air flow in the drying chamber 80, when the process shown in the flowchart in Figure 4 is executed. In Figure 6, P1, P2, and P5 represent the state when the first drying mode operation is being performed, with the first cooler 56a and the first cooling fan 65a operating, and the second cooler 56b and the second cooling fan 65b stopped. The direction of air flow in the drying chamber 80 is the direction of circulation through the first cooler 56a, indicated by D1.

[0035] Furthermore, P3 and P4 indicate that the second drying mode operation is in progress, with the second cooler 56b and second cooling fan 65b operating, and the first cooler 56a and first cooling fan 65a stopped. The direction of air flow in the drying chamber 80 is such that it circulates through the second cooler 56b, as indicated by D2.

[0036] As time passes since the start of the first drying mode operation at P1, a significant amount of frost has accumulated on the first cooler 56a at P2. Then, at P3, the system switches from the first drying mode operation to the second drying mode operation, and the frost accumulated on the first cooler 56a is removed by the operation of the first defrost heater 67a.

[0037] Furthermore, as time passes since the start of the second drying mode operation at P3, a significant amount of frost accumulates on the second cooler 56b at P4. Then, at P5, the system switches from the second drying mode to the first drying mode, and the frost accumulated on the second cooler 56b is removed by the operation of the second defrost heater 67b.

[0038] In this way, by switching between the first drying mode operation and the second drying mode operation and performing them alternately, the frost adhering to the first cooler 56a and the second cooler 56b is removed, thereby suppressing the decrease in drying capacity due to frost formation on the first cooler 56a and the second cooler 56b, and allowing the drying operation to continue.

[0039] [3. Temperature control of the drying room] Referring to Figure 7, the control of the temperature inside the drying chamber 80, which is performed by the operation control unit 21 during the drying operation, will be explained. Figure 7 shows the changes in the temperature detected by the first cooler temperature sensor 57a (Tr1), the temperature detected by the second cooler temperature sensor 57b (Tr2), the temperature detected by the drying chamber temperature sensor 85 (Td, hereinafter referred to as the drying chamber temperature Td), and the humidity inside the drying chamber 80 (hereinafter referred to as the drying chamber humidity H) when the drying operation is performed according to the flowchart shown in Figure 4, with the left vertical axis set to temperature, the right vertical axis set to humidity, and the horizontal axis set to time. The humidity inside the drying chamber 80 is detected by a monitoring humidity sensor set inside the drying chamber 80.

[0040] In Figure 7, Df1 indicates the timing when the system switches from the first drying mode to the second drying mode, and defrosting of the first cooler 56a is performed by the operation of the first defrost heater 67a. Df2 indicates the timing when the system switches from the second drying mode to the first drying mode, and defrosting of the second cooler 56b is performed by the operation of the second defrost heater 67b.

[0041] In the first temperature range from t20 to t21, the operation control unit 21 first starts the first drying mode operation and activates the first cooler 56a to lower the drying chamber temperature Td to a temperature Tc1 (for example, -25°C) of -18°C or lower, thereby freezing the material F to be dried. Subsequently, after a predetermined time has elapsed, the operation control unit 21 activates the first heating heater 66a to raise the drying chamber temperature Td to Tc2 (for example, -3°C) in order to lower the drying chamber humidity H. Then, the operation control unit 21 controls the output of the first heating heater 66a in the first drying mode operation and the output of the second heating heater 66b in the second drying mode operation so that the drying chamber temperature Td is maintained at Tc2. As a result, in the first temperature range, the drying chamber humidity H decreases from 50% to about 20%. Consequently, the moisture in the material F to be dried sublimes while frozen, and drying proceeds.

[0042] Furthermore, the control temperature Tc2 for the drying chamber temperature Td is not limited to -3°C; for example, Tc2 may be set to +3°C to perform the first drying mode operation and the second drying mode operation. The output of the first heating element 66a and the second heating element 66b is controlled, for example, by PWM (Pulse Width Modulation) control, which changes the ratio of the ON time of the heaters (duty cycle) in a predetermined control period.

[0043] The operation control unit 21 switches to controlling the second temperature range from t21 to t22 at t21, when the drying operation in the first temperature range has continued for a predetermined time. In the second temperature range, the operation control unit 21 controls the output of the first heating heater 66a in the first drying mode operation and the output of the second heating heater 66b in the second drying mode operation to raise and maintain the drying room temperature Td to Tc3 (for example, 8°C) in order to further reduce the humidity H in the drying room. As a result, in the second temperature range, the humidity H in the drying room decreases to about 8%.

[0044] As described above, by controlling the drying chamber temperature Td to dry the product F, for example, compared to tomatoes dried by osmotic dehydration with sugar at room temperature, denaturation is suppressed, the "appearance" and "aroma" before storage are preserved, discoloration is reduced, the aroma becomes stronger, and a natural sweetness without added sugar can be obtained, thus improving the sensory evaluation score. Furthermore, since no sugar is added, a healthy dried product without additives can be obtained.

[0045] Furthermore, since drying is performed in the first temperature zone below 0°C, it is expected that there will be less loss of nutrients that are denatured by oxidation, such as vitamin C and total polyphenols, compared to tomatoes dried at room temperature of around 20-30°C (above 0°C) by osmotic dehydration with sugar.

[0046] [4. Effects, etc.] As described above, in this embodiment, the dryer 1 includes a first cooler 56a, a first heating element 66a, and a first cooling fan 65a provided in the first cooling chamber 60a, and a second cooler 56b, a second heating element 66b, and a second cooling fan 65b provided in the second cooling chamber 60b. This allows the dryer to switch between a first drying mode operation in which the first cooler 56a is operated to defrost the second cooler 56b, and a second drying mode operation in which the second cooler 56b is operated to defrost the first cooler 56a. As a result, the dryer can perform drying operations while suppressing a decrease in drying capacity due to frost formation on the first cooler 56a and the second cooler 56b.

[0047] (Other embodiments) As described above, the above embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these embodiments and can be applied to embodiments that have been modified, replaced, added, or omitted. Therefore, other embodiments will be described below as examples.

[0048] In the above embodiment, a configuration is shown that includes a first defrost heater 67a for heating the first cooler 56a and a second defrost heater 67b for heating the second cooler 56b. However, a configuration in which the first defrost heater 67a and the second defrost heater 67b are omitted is also possible. In this case, during the first drying mode operation, frost attached to the second cooler 56b is removed by natural defrosting, and during the second drying mode operation, frost attached to the first cooler 56a is removed by natural defrosting.

[0049] In the above embodiment, the first frost level recognition unit 22 recognized the frost level of the first cooler 56a based on the temperature detected by the first cooler temperature sensor 57a. However, the frost level of the first cooler 56a may be recognized by the configurations of the following Examples 1 to 4. The same applies to the second cooler 56b. Example 1: When the first drying mode operation is performed, the system recognizes that the frost level of the first cooler 56a is high as the elapsed time increases, based on the time elapsed since the start of the first drying mode operation. Example 2: A humidity sensor is installed near the outlet 62a of the first cooling chamber 60a, and when the first drying mode operation is performed, the system recognizes that the lower the detected humidity, the higher the frost level of the first cooler 56a. Example 3…Calculate the rate of decrease in the temperature detected by the first cooler temperature sensor 57a (decrease in temperature per predetermined time / predetermined time, corresponding to the degree of temperature decrease in the detection temperature in this disclosure).The larger the rate of decrease in the temperature detected by the first cooler temperature sensor 57a, the higher the frost level of the first cooler 56a is recognized.Note that the decrease in temperature per predetermined time may be used as the degree of temperature decrease. Example 4…Based on the rate of decrease in the temperature detected by the first cooler temperature sensor 57a, it is recognized that the frost level of the first cooler 56a has increased. Here, Figure 8 is an enlarged view of the Df1 portion (timing when defrosting of the first cooler 56a is performed) shown in Figure 7, showing the change in the temperature Tr1 detected by the first cooler temperature sensor 57a, with the vertical axis set to temperature and the horizontal axis set to time. As shown in Figure 8, when the first drying mode operation is started, the rate of decrease in the temperature Tr1 detected by the first cooler temperature sensor 57a first increases from t31 to t32, then decreases from t32 to t33, and increases again at t33. Therefore, based on the rate of decrease in the temperature Tr1 detected by the first cooler temperature sensor 57a, when the rate of decrease decreases and then increases again at t33, it is recognized that the frost level of the first cooler 56a has increased.

[0050] As an operating mode for drying, the control unit 21 may be configured to perform a third drying mode operation, which involves drying using the third flow path pattern, based on a setting operation by the control unit 2. In this case, the drying capacity can be increased by operating both the first cooler 56a and the second cooler 56b.

[0051] In the above embodiment, the system may be configured to include a first damper that opens and closes at least one of the intake port 61a and outlet port 62a of the first cooling chamber 60a, and a second damper that opens and closes at least one of the intake port 61b and outlet port 62b of the second cooling chamber 60b. In this configuration, when the first drying mode operation is performed, the operation control unit 21 opens the first damper and closes the second damper to prevent the air heated by the second defrost heater 67b from flowing to the drying chamber 80. Furthermore, when the second drying mode operation is performed, the operation control unit 21 opens the second damper and closes the first damper to prevent the air heated by the first defrost heater 67a from flowing to the drying chamber 80.

[0052] In the above embodiment, a single compressor 52 supplied refrigerant to the first cooler 56a and the second cooler 56b. However, a configuration may be provided in which a separate compressor is provided to supply refrigerant to the first cooler 56a and a separate compressor is provided to supply refrigerant to the second cooler 56b. Alternatively, instead of a refrigeration cycle, first and second coolers of other specifications, such as an electronic cooling system equipped with a Peltier element, may be used.

[0053] The control board (control unit) provided in the subject equipment (dryer) in this disclosure may be any controller capable of controlling the operation of the subject equipment in this disclosure. When expressing the subject matter of the invention, in addition to the control board, other similar terms such as control means, control unit, or controller may be used to describe the device that controls the operation of the dryer in this disclosure. The control board can be realized in various forms. For example, the control board may use a processor as the control entity. If a processor is used as the control entity, it becomes possible to perform various processes by having the processor read a program from a storage medium that stores the program and executing the program by the processor. Therefore, since the processing content can be changed by changing the program stored in the storage medium, the degree of freedom in changing the control content can be increased. Examples of processors include CPUs (Central Processing Units) and MPUs (Micro-Processing Units). Examples of storage mediums include hard disks, flash memory, and optical discs. Furthermore, wired logic, which cannot be rewritten, may be used as the control entity of the control board. Using wired logic as the control entity of the control board is effective in improving processing speed. Examples of wired logic include ASICs (Application Specific Integrated Circuits). Alternatively, a controller may be implemented by combining a processor and wired logic. Implementing the control entity of a control board by combining a processor and wired logic increases the flexibility of software design while improving processing speed. Furthermore, the control entity of a control board and a circuit with a different function may be constructed from a single semiconductor element. An example of a circuit with a different function is an A / D / D / A conversion circuit. The control entity may also be constructed from a single semiconductor element or from multiple semiconductor elements. When constructed from multiple semiconductor elements, each control described in the claims may be implemented from different semiconductor elements. Additionally, the control board may be constructed from a configuration including semiconductor elements and passive components such as resistors or capacitors.

[0054] Since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or equivalents thereof.

[0055] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0056] (Technical 1) A dryer comprising: a drying chamber for containing the material to be dried; a first cooling chamber connected to the drying chamber by a first intake port and a first outlet port, with a first cooler and a first heating element arranged between the first intake port and the first outlet port in order from upstream; a first cooling fan for circulating the air in the drying chamber through the first cooling chamber; a second cooling chamber connected to the drying chamber by a second intake port and a second outlet port, with a second cooler and a second heating element arranged between the second intake port and the second outlet port in order from upstream; and a second cooling fan for circulating the air in the drying chamber through the second cooling chamber. With this configuration, by providing two separate first and second cooling chambers as airflow paths for circulating and drying the air within the drying chamber, the first cooler, first heating element, and first cooling fan located in the first cooling chamber can be operated to dry the undried material inside the drying chamber, while the operation of the second cooler located in the second cooling chamber can be stopped to defrost the second cooler. Similarly, the second cooler, second heating element, and second cooling fan located in the second cooling chamber can be operated to dry the undried material inside the drying chamber, while the operation of the first cooler located in the first cooling chamber can be stopped to defrost the first cooler. In this way, by switching between the airflow paths of the first and second cooling chambers, it is possible to defrost one of the first or second coolers while continuing drying using the other, thereby suppressing a decrease in drying capacity due to frost formation on the coolers.

[0057] (Technical 2) The dryer according to Technical 1, comprising a control unit that performs a mode switching drying operation, which switches between a first drying mode in which the first cooler and the first cooling fan are in an operating state and the second cooler and the second cooling fan are in a stopped state, and a second drying mode in which the second cooler and the second cooling fan are in an operating state and the first cooler and the first cooling fan are in a stopped state, based on predetermined switching conditions. This configuration includes a control unit that performs a mode-switching drying operation, which switches between a first drying mode operation and a second drying mode operation based on switching conditions. This allows for a control process that defrosts one of the first or second coolers while continuing drying using the other.

[0058] (Technical 3) The dryer according to Technical 1, further comprising a first defrost heater for heating the first cooler and a second defrost heater for heating the second cooler. With this configuration, by providing a first defrost heater and a second defrost heater, the time required for defrosting the first and second coolers can be shortened compared to the case of natural defrosting without heaters.

[0059] (Technical 4) The dryer according to Technical 3, comprising a control unit that performs a mode switching drying operation which switches between a first drying mode operation in which the first cooler and the first cooling fan are in operation and the first defrost heater is stopped, and the second cooler and the second cooling fan are stopped and the second defrost heater is operated, and a second drying mode operation in which the second cooler and the second cooling fan are in operation and the second defrost heater is stopped, and the first cooler and the first cooling fan are stopped and the first defrost heater is operated, based on predetermined switching conditions. With this configuration, by providing a control unit that performs a mode-switching drying operation that switches between a first drying mode operation and a second drying mode operation based on switching conditions, it is possible to perform a control process that continues drying using the other while defrosting is performed using the first or second defrost heater of one of the first or second coolers.

[0060] (Technical 5) The dryer according to Technical 2 or Technical 4, further comprising: a first frost level recognition unit for recognizing the frost level of the first cooler; and a second frost level recognition unit for recognizing the frost level of the second cooler, wherein the switching condition from the first drying mode operation to the second drying mode operation is set to be that the frost level of the first cooler recognized by the first frost level recognition unit is equal to or greater than a first determination level; and the switching condition from the second drying mode operation to the first drying mode operation is set to be that the frost level of the second cooler recognized by the second frost level recognition unit is equal to or greater than a second determination level. With this configuration, the first drying mode operation and the second drying mode operation can be switched at an appropriate timing based on the frost accumulation level of the first and second coolers.

[0061] (Technical 6) The dryer according to Technical 5, further comprising a first cooler temperature sensor for detecting the temperature of the first cooler and a second cooler temperature sensor for detecting the temperature of the second cooler, wherein the first frost level recognition unit recognizes that the greater the decrease in the temperature detected by the first cooler temperature sensor, the higher the frost level of the first cooler, and the second frost level recognition unit recognizes that the greater the decrease in the temperature detected by the second cooler temperature sensor, the higher the frost level of the second cooler, based on the degree of decrease in the temperature detected by the second cooler temperature sensor. With this configuration, by including a first cooler temperature sensor and a second cooler temperature sensor, the frost levels of the first and second coolers can be accurately recognized.

[0062] (Technical 7) The dryer according to Technical 5, wherein the first frost level recognition unit recognizes that the longer the duration of the first drying mode operation, the higher the frost level of the first cooler, and the second frost level recognition unit recognizes that the longer the duration of the second drying mode operation, the higher the frost level of the second cooler, based on the duration of the second drying mode operation. This configuration allows for the recognition of frost levels in the first and second coolers using a simple setup that does not require temperature sensors or the like.

[0063] (Technology 8) A dryer according to any one of the technologies 2, 4 to 7, wherein the control unit selectively performs a third drying mode operation in which the first cooler and the first heating heater are operated, as well as the second cooler and the second heating heater, and the mode switching drying operation. With this configuration, the third drying mode operation can increase drying capacity compared to mode switching operation, allowing for the drying of undried items in the drying chamber. [Industrial applicability]

[0064] This disclosure is applicable to applications in dryers where a decrease in drying capacity due to frost formation on the cooler is suppressed. [Explanation of Symbols]

[0065] 1 Dryer 2 Control section 10 Control Unit 20 processors 21 Operation Control Unit 22. First frost level recognition unit 23. Second frost level recognition unit 30 memory 31 Programs 32. Operating Conditions Data 50 refrigeration cycles 51 Refrigerant Circuit 52 Compressor 53 Heat sink 54 Three-way valve 55a First expansion valve 55b Second expansion valve 56a 1st cooling section 56b 2nd cooler 57a First cooler temperature sensor 57b Second cooler temperature sensor 60a First Cooling Chamber 60b 2nd cooling room 61a First intake port 61b Second intake port 62a First outlet 62b Second air outlet 65a First Cooling Fan 65b Second cooling fan 66a First heating element 66b Second heating element 70 First channel 71 Second channel 80 Drying room 81 shelves 81a Communication hole 82 First stirring fan 83. Second stirring fan 85 Drying chamber temperature sensor 90 1st side plate 91 Second side plate 92 Opening 93, 94, 95, 96 Slits provided in the first and second side plates.

Claims

1. A drying chamber for containing the material to be dried, A first cooling chamber is connected to the drying chamber by a first intake port and a first outlet port, and a first cooler and a first heating element are arranged between the first intake port and the first outlet port in order from the upstream side. A first cooling fan circulates the air in the drying chamber via the first cooling chamber, A second cooling chamber is connected to the drying chamber by a second intake port and a second outlet port, and a second cooler and a second heating element are arranged between the second intake port and the second outlet port in order from the upstream side. A second cooling fan circulates the air in the drying chamber through the second cooling chamber, A dryer equipped with a dryer.

2. The system includes a control unit that performs a mode-switching drying operation, which switches between a first drying mode operation in which the first cooler and the first cooling fan are activated and the second cooler and the second cooling fan are stopped, and a second drying mode operation in which the second cooler and the second cooling fan are activated and the first cooler and the first cooling fan are stopped, based on predetermined switching conditions. The dryer according to claim 1.

3. A first defrost heater for heating the first cooler, A second defrost heater for heating the second cooler, The dryer according to claim 1, comprising:

4. The system includes a control unit that performs a mode-switching drying operation, which switches between a first drying mode operation, in which the first cooler and the first cooling fan are in operation and the first defrost heater is stopped, and the second cooler and the second cooling fan are stopped and the second defrost heater is operated, and a second drying mode operation, in which the second cooler and the second cooling fan are in operation and the second defrost heater is stopped, and the first cooler and the first cooling fan are stopped and the first defrost heater is operated, based on predetermined switching conditions. The dryer according to claim 3.

5. A first frost level recognition unit recognizes the frost level of the first cooler, The system includes a second frost level recognition unit that recognizes the frost level of the second cooler, The conditions for switching from the first drying mode operation to the second drying mode operation are set to be that the frost level of the first cooler recognized by the first frost level recognition unit is equal to or greater than the first determination level, and the conditions for switching from the second drying mode operation to the first drying mode operation are set to be that the frost level of the second cooler recognized by the second frost level recognition unit is equal to or greater than the second determination level. The dryer according to claim 2 or claim 4.

6. A first cooler temperature sensor for detecting the temperature of the first cooler, The system includes a second cooler temperature sensor for detecting the temperature of the second cooler, The first frost level recognition unit recognizes that the frost level of the first cooler is higher the greater the decrease in the temperature detected by the first cooler temperature sensor, based on the degree of decrease in the temperature detected by the first cooler temperature sensor. The second frost level recognition unit recognizes that the frost level of the second cooler is higher the greater the decrease in the temperature detected by the second cooler temperature sensor. The dryer according to claim 5.

7. The first frost level recognition unit recognizes, based on the duration of the first drying mode operation, that the longer the duration of the first drying mode operation, the higher the frost level of the first cooler. The second frost level recognition unit recognizes, based on the duration of the second drying mode operation, that the longer the duration of the second drying mode operation, the higher the frost level of the second cooler. The dryer according to claim 5.

8. The control unit selectively performs a third drying mode operation, which operates the first cooler and the first heating element, as well as the second cooler and the second heating element, and the mode switching drying operation. The dryer according to claim 2 or claim 4.

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