Dryer

Abstract

The objective is to provide a dryer with improved reliability of the heat pump system. We can provide a dryer. [Solution] The dryer according to the present disclosure comprises a storage tank for storing an object, a heat pump device connecting a compressor, a condenser, an expansion mechanism, and an evaporator with refrigerant piping for circulating refrigerant, an air passage member defining an air passage between the storage tank and the heat pump device, a fan provided in the air passage member for circulating air between the storage tank and the heat pump device, a filter for collecting foreign matter contained in the refrigerant flowing through the refrigerant piping, and a control unit for controlling the compressor and the expansion mechanism. The expansion mechanism has a flow rate adjustment unit that can change the flow rate of the incoming refrigerant, and the control unit is capable of performing a drying process in which the compressor is operated, and a recovery process in which the compressor is operated and the flow rate adjustment unit is controlled so that a larger flow rate than that in the drying process flows into the expansion mechanism.

Description

[Technical Field]

[0001] The present disclosure relates to a dryer. [Background Art]

[0002] For example, Patent Document 1 discloses a dryer including a heat pump device and a control device. The heat pump device includes a compressor, a condenser, a flow rate control valve that changes a flow rate of a refrigerant, and an evaporator, which are connected in sequence. The control device controls an opening degree of the flow rate control valve.

[0003] In the dryer described in Patent Document 1, the control device executes control to gradually reduce the opening degree of the flow rate control valve. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2009-61163 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, in Patent Document 1, since the opening degree of the flow rate control valve is reduced, foreign matter carried by the refrigerant is more likely to clog the flow rate control valve. Therefore, there is still room for improvement in terms of suppressing clogging of the flow rate control valve with foreign matter and improving the reliability of the heat pump device.

[0006] An object of the present disclosure is to solve the above problem and provide a dryer with improved reliability of a heat pump device. [Means for Solving the Problem]

[0007] A dryer according to one aspect of the present disclosure comprises a storage tank for storing an object, a heat pump device connecting a compressor, a condenser, an expansion mechanism, and an evaporator via refrigerant piping for circulating a refrigerant, an air passage member defining an air passage between the storage tank and the heat pump device, a fan provided in the air passage member for circulating air between the storage tank and the heat pump device, a filter for collecting foreign matter contained in the refrigerant flowing through the refrigerant piping, and a control unit for controlling the compressor and the expansion mechanism, wherein the expansion mechanism has a flow rate adjustment unit capable of changing the flow rate of the incoming refrigerant, and the control unit is capable of performing a drying step of operating the compressor and a recovery step of operating the compressor and controlling the flow rate adjustment unit so that a larger flow rate than that of the drying step flows into the expansion mechanism. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a dryer that shortens the drying process time. [Brief explanation of the drawing]

[0009] [Figure 1] Schematic cross-sectional view of a dryer according to the embodiment of this disclosure [Figure 2] Schematic diagram of a heat pump system [Figure 3] Mollier diagram of the thermal cycle realized by a heat pump device [Figure 4A] Schematic diagram of an electronic expansion valve [Figure 4B] Schematic diagram of an electronic expansion valve [Figure 5] Schematic diagram of an electronic expansion valve clogged with foreign matter. [Figure 6] Schematic diagram of an electronic expansion valve through which foreign objects pass. [Figure 7] Flowchart of the driving route [Figure 8] Flowchart of the recovery and drying processes [Figure 9] Operational diagram showing the opening degree of the electronic expansion valve and the rotation speed of the compressor during the recovery and drying processes. [Modes for carrying out the invention]

[0010] (Embodiment 1) A dryer 1 according to an embodiment of the present disclosure will be described. The dryer 1 is an apparatus that performs a drying process for drying objects to be dried such as wet clothes, towels and bed sheets. In Embodiment 1, the dryer 1 is a washer-dryer that further has a washing function (a so-called drum-type washer-dryer). Note that the dryer 1 may not have a washing function.

[0011] FIG. 1 is a schematic cross-sectional view of the dryer 1 according to Embodiment 1 of the present disclosure. FIG. 2 is a schematic diagram of the heat pump device 6.

[0012] In FIG. 1, two directions orthogonal to each other in a horizontal plane are defined as a width direction X and a front-rear direction Y, and a vertical direction orthogonal to the horizontal plane is defined as a up-down direction Z.

[0013] As shown in FIG. 1, the dryer 1 includes a housing 2, an outer tub 3, a storage tub 4, a driving part 5, a heat pump device 6, a case 8, an air duct member 9, a fan 10, and a control part 12.

[0014] The housing 2 is a member that forms the outer appearance of the dryer 1. An opening 20 and an openable / closable door 21 covering the opening 20 are provided on the front surface of the housing 2.

[0015] The outer tub 3 is a substantially cylindrical member provided inside the housing 2 and having a function of storing washing water. The outer tub 3 may also be referred to as a water tank or a tub. The outer tub 3 is provided with an opening 31 at a position facing the opening 20 of the housing 2, and an edge of the opening 31 is connected to the opening 20 by a bellows 32.

[0016] The storage tub 4 is a substantially cylindrical member rotatably provided around the rotation axis V0 inside the outer tub 3 and capable of storing an object. The storage tub 4 may also be referred to as a drum, an inner tub or a washing tub. A plurality of through holes 40 are formed in the storage tub 4, and the through holes 40 allow communication between the storage tub 4 and the outer tub 3. The storage tub 4 is provided with an opening 41 at a position facing the opening 20 of the housing 2 and the opening 31 of the outer tub 3. When a user of the dryer 1 opens the door 21, the user can put an object into the storage tub 4 through the openings 20, 31, and 41.

[0017] The rotation axis V0 of the storage tub 4 extends inclining downward toward the rear side (+Y side). Note that the rotation axis V0 may extend parallel to the horizontal direction.

[0018] The drive unit 5 is a member that rotationally drives the storage tub 4 around the rotation axis V0. The drive unit 5 includes, for example, a motor that rotates the storage tub 4.

[0019] The heat pump device 6 is a device that adjusts the humidity and temperature of passing air. As shown in FIG. 2, the heat pump device 6 includes a compressor 61, an expansion mechanism 62, an evaporator 63, a condenser 64, and a refrigerant pipe 65. The evaporator 63, the compressor 61, the condenser 64, and the expansion mechanism 62 are sequentially connected by the refrigerant pipe 65 that circulates a refrigerant.

[0020] The evaporator 63 is a heat exchanger that cools surrounding air by vaporizing an inflowing refrigerant. The evaporator 63 dehumidifies the air by cooling the air to condense moisture contained in the air. The evaporator 63 may also be referred to as a cooler or a dehumidifying heat exchanger. The evaporator 63 includes, for example, a plurality of fins formed of thin metal plates, and heat transfer tubes that are provided penetrating through the surfaces of the fins, communicate with the refrigerant pipe 65, and allow the refrigerant to flow therethrough.

[0021] The refrigerant in the evaporator 63 changes from a two-phase state in which a gas phase and a liquid phase are mixed to a gas phase state from a refrigerant inlet toward a refrigerant outlet. Therefore, the refrigerant flowing out of the evaporator 63 is sent to the compressor 61 in a gas phase state. Failure of the compressor 61 can be suppressed by inhibiting liquid from flowing into the compressor 61.

[0022] The compressor 61 is a device that compresses the incoming refrigerant. Specifically, the compressor 61 has a rotating mechanism and compresses the refrigerant by the kinetic energy of the rotating mechanism. The compression ratio of the refrigerant is determined by the rotational speed K of the compressor 61 and the opening degree of the electronic expansion valve 66. The compressed refrigerant is sent to the condenser 64. An accumulator 60 is connected to the compressor 61. The accumulator 60 is capable of holding a certain volume of liquid refrigerant.

[0023] Let P1 be the pressure of the refrigerant flowing into the compressor 61 (i.e., the pressure on the low-pressure side), and P2 be the pressure on the high-pressure side after compression. To prevent failure of the compressor 61, an upper limit P0 is set for the high-pressure side pressure P2. Since the compression ratio of the refrigerant is determined by the rotational speed K of the compressor 61, an upper limit (threshold K0) is similarly set for the rotational speed K of the compressor 61.

[0024] The condenser 64 is a heat exchanger that heats the surrounding air by liquefying the incoming refrigerant. The condenser 64 may also be referred to as a heater or a heating heat exchanger. The condenser 64 has, for example, multiple fins and heat transfer tubes, similar to the evaporator 63.

[0025] The refrigerant in the condenser 64 changes from a gaseous state to a two-phase state and then to a liquid state as it moves from the refrigerant inlet to the refrigerant outlet in the condenser 64. The refrigerant that flows out of the condenser 64 is sent to the expansion mechanism 62.

[0026] The expansion mechanism 62 is a mechanism that reduces the pressure of the refrigerant flowing in from the condenser 64. In Embodiment 1, the expansion mechanism 62 has an electronic expansion valve 66 (see Figure 3) that can change the flow rate of the refrigerant flowing into the expansion mechanism 62. The expansion mechanism 62 may have other expansion valves instead of the electronic expansion valve 66. The reduced-pressure refrigerant is sent to the evaporator 63 and circulates within the heat pump device 6.

[0027] In the drying process, when the compressor 61 is rotated while maintaining the rotational speed K below the threshold K0, the expansion mechanism 62 reduces the flow rate of the refrigerant by the electronic expansion valve 66 so that the suction superheat (SH), described later, does not fall below a predetermined value. For this reason, in the drying process, an upper limit (threshold Q0) is set for the flow rate Q of the refrigerant by the electronic expansion valve 66.

[0028] Returning to Figure 1, in Embodiment 1, the evaporator 63 and the condenser 64 are arranged side by side in the front-to-back direction Y. Specifically, the evaporator 63 and the condenser 64 are arranged such that the main surfaces of the fins of the evaporator 63 and the condenser 64 face the width direction X and extend in the front-to-back direction Y. Considering the airflow (see arrow A), the evaporator 63 is located upstream of the condenser 64, and the air passes through the evaporator 63 and the condenser 64 in sequence, being dehumidified and heated.

[0029] The heat pump unit 6 is located at the top of the housing 2. Specifically, the heat pump unit 6 is located above the outer tank 3.

[0030] Case 8 is a component that houses the heat pump device 6. Case 8 has an inlet 81 upstream of the evaporator 63 and an outlet 82 downstream of the condenser 64. In Embodiment 1, the inlet 81 and outlet 82 are aligned in the front-to-back direction Y, and the air inside Case 8 flows from the inlet 81 towards the outlet 82, towards the rear (+Y side).

[0031] The air passage member 9 is provided inside the housing 2 and defines an air passage R between the housing tank 4 and the heat pump device 6. In Embodiment 1, the air passage member 9 has a first air passage member 91 and a second air passage member 92. The first air passage member 91 connects an opening 33 provided in the outer tank 3 to an inlet 81 of the case 8. The second air passage member 92 connects an outlet 82 of the case 8 to an opening 34 provided in the outer tank 3.

[0032] The air passage member 9 is equipped with multiple temperature sensors 74 for measuring the temperature of the air flowing through it. One temperature sensor 74 is located near the opening 33 of the outer tank 3. This arrangement allows for measurement of the air temperature both upstream and downstream of the containment tank 4. The temperature sensors 74 may be located at any position on the air passage member 9 or on the outer tank 3.

[0033] Fan 10 is installed in the air passage member 9 and circulates air between the storage tank 4 and the heat pump device 6. Fan 10 circulates the air that has passed through the case 8 back to the storage tank 4 (see arrow A). Specifically, when fan 10 is driven, humid air from the storage tank 4 flows into the case 8 from the inlet 81 through the first air passage member 91. The air that has been dehumidified and heated by the heat pump device 6 is returned to the storage tank 4 from the outlet 82 of the case 8 through the second air passage member 92.

[0034] Fan 10 may have any type of fan, for example, an axial fan or a centrifugal fan.

[0035] In Embodiment 1, the fan 10 is positioned downstream of the heat pump device 6.

[0036] The control unit 12 is a device that controls the operation of the dryer 1. The control unit 12 controls the components of the dryer 1, such as the drive unit 5, the heat pump device 6, and the fan 10. The control unit 12 may, for example, include a storage unit 13 that stores various information and programs, and a processing circuit (not shown) corresponding to a processor such as a CPU, and the processor may function as these elements by executing programs. The storage unit 13 is a recording medium and may be a memory that functions as a working area for the control unit 12. The storage unit 13 may be implemented as, for example, flash memory, SSD (Solid State Device), hard disk, RAM, other storage devices, or a combination thereof as appropriate.

[0037] The control unit 12 controls the compressor 61 and the electronic expansion valve 66 of the expansion mechanism 62 in the heat pump device 6. Specifically, in the drying process, the control unit 12 controls the compressor 61 so that its rotational speed K is less than or equal to a threshold K0. Also in the drying process, the control unit 12 controls the electronic expansion valve 66 so that the refrigerant flow rate is less than or equal to a threshold Q0.

[0038] Next, the heat pump device 6 will be described in more detail with reference to Figures 2 and 3. Figure 3 is a Mollier diagram showing the relationship between pressure P and enthalpy H in the thermal cycle realized by the heat pump device 6. In Figure 3, line R1 represents the change in the compressor 61, line R2 represents the change in the expansion mechanism 62, line R3 represents the change in the evaporator 63, and line R4 represents the change in the condenser 64.

[0039] As shown in Figure 2, the heat pump device 6 further includes a first sensor 71, a second sensor 72, and a third sensor 73 for measuring the temperature of the refrigerant. In this specification, sensors 71 to 73 measure the temperature of the pipes through which the refrigerant flows, and estimate the temperature of the measured pipes to be the temperature of the refrigerant itself.

[0040] The temperature measured by sensors 71-73 allows for the estimation of the state of the thermal cycle realized by the heat pump device 6. Specifically, as shown in Figure 3, based on a Mollier diagram assuming an isentropic state (i.e., the compressor 61 is operating at 100% efficiency), the temperature measured by sensors 71-73 allows for the estimation of the refrigerant pressure and the temperature of the refrigerant at other locations.

[0041] The first sensor 71 is located in the condenser 64 and measures the first temperature T1 of the refrigerant in the condenser 64. In Embodiment 1, the first sensor 71 is located in the condenser 64 at a position where the refrigerant is in a two-phase state where the liquid phase and gas phase are mixed. The first sensor 71 is located, for example, in the center of the condenser 64.

[0042] The first temperature T1 is correlated with the high-pressure side pressure P2 of the compressor 61. Therefore, the high-pressure side pressure P2 can be estimated from the first temperature T1. Since an upper limit P0 is set for the high-pressure side pressure P2, it is necessary to suppress an excessive increase in the first temperature T1, and a first threshold S1 corresponding to the upper limit P0 is set for the first temperature T1. If the state in which the first temperature T1 exceeds the first threshold S1 continues for a predetermined time, it is necessary to stop the compressor 61.

[0043] The second sensor 72 is located at the refrigerant inlet of the evaporator 63 and measures the second temperature T2 of the refrigerant flowing into the evaporator 63.

[0044] The second temperature T2 is an indicator of the phase state of the refrigerant in the evaporator 63. Specifically, based on the second temperature T2, the proportion of the refrigerant in a two-phase state within the evaporator 63 can be estimated. That is, based on the second temperature T2, the location within the evaporator 63 where the refrigerant switches from a two-phase state to a gaseous state can be estimated.

[0045] The third sensor 73 is located between the compressor 61 and the condenser 64 and measures the third temperature T3 of the refrigerant discharged from the compressor 61. In Embodiment 1, the third sensor 73 is located in the discharge pipe of the compressor 61, where the refrigerant is discharged toward the condenser 64. Therefore, the third temperature T3 measured by the third sensor 73 may also be referred to as the discharge pipe temperature.

[0046] The third temperature T3 correlates with the refrigerant pressure P2 on the high-pressure side of the compressor 61. Therefore, in addition to the first temperature T1, the high-pressure side pressure P2 can also be estimated from the third temperature T3. Since an upper limit P0 is set for the high-pressure side pressure P2, a fifth threshold S5 is also set for the third temperature T3. If the third temperature T3 exceeds the fifth threshold S5 for a predetermined period of time, the compressor 61 is required to be stopped.

[0047] From the temperature difference between the third temperature T3 and the second temperature T2, the temperature difference of the refrigerant at the refrigerant outlet and refrigerant inlet of the evaporator 63 can be estimated. The temperature difference of the refrigerant at the refrigerant outlet and refrigerant inlet of the evaporator 63 may also be called the suction superheat (SH). Suction SH is an indicator of the heat conversion efficiency of the evaporator 63, and a stable suction SH indicates that the evaporator 63 is being used with high efficiency. Suction SH varies depending on the operating conditions of the heat pump device 6 and the progress of the drying process, and is, for example, between 1°C and 10°C.

[0048] Furthermore, if the operation of the compressor 61 deviates significantly from the ideal isentropic state, i.e., the state of 100% operating efficiency, an additional sensor may be installed between the evaporator 63 and the compressor 61 to measure the temperature of the refrigerant flowing into the compressor 61. In this case, the suction SH is the difference between the temperature measured by the additional sensor and the second temperature T2.

[0049] Furthermore, the temperature difference between the refrigerant inlet and outlet of the condenser 64 can be estimated from the temperature difference between the third temperature T3 and the first temperature T1. The temperature difference between the refrigerant inlet and outlet of the condenser 64 may be called the discharge superheat (SH). Discharge SH is an indicator of the heat conversion efficiency of the condenser 64, and a stable discharge SH indicates that the condenser 64 is being used with high efficiency.

[0050] As shown in Figure 2, the heat pump device 6 further includes a filter 69. The filter 69 is installed in the accumulator 60 between the evaporator 63 and the compressor 61 and is a component that collects foreign matter suspended in the refrigerant flowing through the refrigerant piping 65. By providing the filter 69, it is possible to suppress the flow of foreign matter into the compressor 61 and cause it to malfunction.

[0051] The filter 69 has a mesh that allows the refrigerant to pass through while capturing foreign matter. The filter 69 may also be called a strainer.

[0052] Foreign matter suspended in the refrigerant includes, for example, substances mixed in when the refrigerant is injected into the refrigerant piping 65, and solder that has peeled off from the brazed joints of the heat transfer tubes of the evaporator 63 or condenser 64.

[0053] Figures 4A and 4B are schematic diagrams of a portion of the electronic expansion valve 66 of the expansion mechanism 62.

[0054] As shown in Figures 4A and 4B, the electronic expansion valve 66 has a cylindrical portion 75 and a needle 76. The cylindrical portion 75 is a cylindrical member with an opening 75A defined at its tip. The needle 76 is a rod-shaped member with a tapered shape, which is inserted into the cylindrical portion 75 and can seal the opening 75A. The needle 76 is movable in the longitudinal direction L relative to the cylindrical portion 75 between a position that seals the opening 75A and a position that opens the opening 75A.

[0055] The needle 76 has a first tapered portion 77 and a second tapered portion 78 in order toward the tip 76A. The sides of the tapered portions 77 and 78 are inclined at an angle with respect to the longitudinal direction L, and the cross-sectional area of ​​the needle 76 perpendicular to the longitudinal direction L decreases toward the tip 76A of the needle 76.

[0056] The inclination angle of the second tapered section 78 is smaller than that of the first tapered section 77. Therefore, the rate of change of the cross-sectional area per unit length in the longitudinal direction L is smaller for the second tapered section 78 than for the first tapered section 77.

[0057] As the needle 76 moves in the longitudinal direction L, the distance between the side surface of the needle 76 and the edge of the cylindrical portion 75 that defines the opening 75A changes, and the area of ​​the open opening 75A changes. The area of ​​the open opening 75A may also be called the degree of opening.

[0058] For example, when the needle 76 moves from the position shown in Figure 4A to the position shown in Figure 4B, the gap G1 decreases to the gap G2, and the opening decreases. On the other hand, when the needle 76 moves in the opposite direction, the opening increases.

[0059] The flow rate of refrigerant flowing into the expansion mechanism 62 through the opening 75A can be adjusted by increasing or decreasing the opening. When the opening decreases, the flow rate of refrigerant flowing into the expansion mechanism 62 also decreases, and when the opening increases, the flow rate of refrigerant flowing into the expansion mechanism 62 also increases.

[0060] The opening degree of the electronic expansion valve 66 (the amount of movement of the needle 76 in the longitudinal direction L) is controlled by the control unit 12. In Embodiment 1, in the drying process in which the heat pump device 6 is mainly used, the control unit 12 controls the movement of the needle 76 within the range in which the second tapered portion 78 is inserted into the opening 75A. Specifically, in the drying process, the control unit 12 controls the movement of the needle 76 so that the opening degree is less than or equal to the threshold J0. The threshold J0 is the opening degree at which the flow rate of the refrigerant becomes the threshold Q0.

[0061] Furthermore, since the needle 76 moves within the range in which the second tapered portion 78 is inserted into the opening 75A, the increase or decrease in the opening degree with respect to the amount of movement in the longitudinal direction L can be reduced compared to the case where the first tapered portion 77 moves within the range in which it is inserted into the opening 75A. Therefore, the opening degree can be controlled with higher precision.

[0062] Figure 5 is a schematic diagram of the electronic expansion valve 66 when it is clogged with foreign matter C. Figure 6 is a schematic diagram of the electronic expansion valve 66 through which foreign matter C passes.

[0063] As shown in Figure 5, in a drying process, when the second tapered portion 78 is inserted into the opening 75A and the gap G between the side of the needle 76 and the edge of the cylindrical portion 75 is narrowed, there is a risk that foreign matter C may get stuck in the gap G and become fixed to the electronic expansion valve 66.

[0064] On the other hand, as shown in Figure 6, when the tip 76A of the needle 76 is separated from the opening 75A, and the entire opening 75A is open, foreign matter C can pass through the opening 75A. The foreign matter C that has passed through flows through the refrigerant piping 65 and is eventually collected in the filter 69.

[0065] Therefore, in a drying process with a narrow spacing G, in order to prevent foreign matter C from clogging the electronic expansion valve 66, a recovery process is performed before the drying process is carried out by opening the opening 75A and recovering the foreign matter C.

[0066] [Example of operation] Next, an example of the operation of the dryer 1 having the above configuration will be described. Figure 7 is a flowchart of the operating course performed by the dryer 1. Figure 8 is a flowchart of the recovery process and the drying process. Figure 9 is an operation diagram showing the opening degree J of the electronic expansion valve 66 and the rotational speed K of the compressor 61 in the recovery process and the drying process.

[0067] As shown in Figure 7, first, the control unit 12 accepts the operation course to be executed in response to, for example, the user's operation of the dryer 1 (S11).

[0068] Next, the control unit 12 determines whether the received operating course includes a drying process (S12). Specifically, the control unit 12 refers to the storage unit 13 to obtain information about the received operating course and determines whether or not a drying process is included based on the obtained information.

[0069] If the accepted operating course does not include a drying process (No in S12), the control unit 12 executes the operating course and then terminates its operation.

[0070] If the accepted operating course includes a drying process (Yes in S12), the control unit 12 starts the operating course and executes the recovery process (S13) before the drying process (S14). The control unit 12 may also execute the recovery process immediately before the drying process. For example, if the accepted operating course is a wash-and-dry course, the control unit 12 executes the washing process, rinsing process, and spin-drying process in order, and then executes the recovery process immediately before executing the drying process. The control unit 12 may also execute the recovery process before the drying process and immediately before any other process.

[0071] If the dryer 1 has a display unit that displays information about the operating course, the display unit may display information about the process being executed, such as the name of the process being executed. On the other hand, while the recovery process is being executed, the display unit may display information about the process to be executed immediately before or after, such as the drying process.

[0072] Here, the recovery process and drying process will be explained in more detail. As shown in Figure 8, first, the control unit 12 changes the opening degree J of the electronic expansion valve 66 to the first opening degree J1 (S21). The first opening degree J1 is, for example, a predetermined value stored in the memory unit 13, and the control unit 12 obtains the first opening degree J1 by referring to the memory unit 13.

[0073] As shown in Figure 9, the first opening degree J1 is greater than the opening degree J of the electronic expansion valve 66 in the drying process. Specifically, the first opening degree J1 is greater than the maximum opening degree of the electronic expansion valve 66 in the drying process. In Embodiment 1, the maximum opening degree of the electronic expansion valve 66 in the drying process is the threshold J0, and the first opening degree J1 is greater than the threshold J0.

[0074] The threshold J0 may be the maximum opening of the electronic expansion valve 66 during normal operation of the drying process. The threshold J0 may also be smaller than the maximum opening of the electronic expansion valve 66 during emergency operation performed when the control unit 12 detects an abnormality. The first opening J1 may also be smaller than the maximum opening of the electronic expansion valve 66 during emergency operation.

[0075] During the recovery process, the compressor 61 performs a startup. Before startup, the accumulator 60 is empty and capable of holding a certain volume of liquid refrigerant. During startup, a certain amount of liquid return to the compressor 61 is permitted depending on the volume of the accumulator 60. Therefore, even if liquid return occurs when the opening degree J of the electronic expansion valve 66 is changed to a first opening degree J1 which is greater than the threshold J0, failure of the compressor 61 due to liquid return can be suppressed.

[0076] As shown in Figure 6, in Embodiment 1, the first opening degree J1 is the opening degree J when the tip 76A of the needle 76 is separated from the opening 75A of the cylindrical portion 75 in the longitudinal direction L, that is, the opening degree J when the entire opening 75A is open. Note that the first opening degree J1 only needs to be greater than the opening degree of the electronic expansion valve 66 in the drying process, and a part of the opening 75A may be blocked by the needle 76.

[0077] As shown in Figure 9, if the operating course is a wash-and-dry course and the dewatering process is performed before the recovery process, the control unit 12 increases the opening degree J of the electronic expansion valve 66 to the first opening degree J1.

[0078] In a process prior to the recovery process, or before the start of the operating course, the control unit 12 may set the opening degree J of the electronic expansion valve 66 to the first opening degree J1. This operation can equalize the refrigerant pressure between the evaporator 63 and the condenser 64. If the compressor 61 is started after the opening degree J of the electronic expansion valve 66 has been set to the first opening degree J1 in a process prior to the recovery process, the control unit 12 may decrease the opening degree J of the electronic expansion valve 66. Alternatively, the control unit 12 may maintain the first opening degree J1.

[0079] As shown in Figure 8, the control unit 12 then drives the compressor 61 by changing the rotational speed K of the compressor 61 to the first rotational speed K1 (S22). The first rotational speed K1 is, for example, a predetermined value stored in the memory unit 13, and the control unit 12 obtains the first rotational speed K1 by referring to the memory unit 13.

[0080] As shown in Figure 9, the first rotational speed K1 is smaller than the rotational speed K of the compressor 61 in the drying process. Specifically, the first rotational speed K1 is smaller than the maximum rotational speed of the compressor 61 in the drying process. In Embodiment 1, the maximum rotational speed of the compressor 61 in the drying process is the threshold K0, and the first rotational speed K1 is smaller than the threshold K0.

[0081] In Embodiment 1, the first rotational speed K1 is greater than the rotational speed K of the compressor 61 in the dewatering process. The rotational speed K of the compressor 61 in the dewatering process may be a predetermined rotational speed at the start of operation of the compressor 61.

[0082] When the compressor 61 is driven, the refrigerant circulates through the heat pump device 6. Since the opening degree J of the electronic expansion valve 66 is the first opening degree J1, foreign matter suspended in the circulating refrigerant can pass through the expansion mechanism 62. The suspended foreign matter reaches the filter 69 and is collected by the filter 69.

[0083] In Embodiment 1, during the recovery process, the control unit 12 maintains the opening degree J of the electronic expansion valve 66 at a constant first opening degree J1, and maintains the rotational speed K of the compressor 61 at a constant first rotational speed K1. Since the first opening degree J1 is greater than the threshold J0 and the first rotational speed K1 is less than the threshold K0, the pressure P2 on the high-pressure side is less likely to reach the upper limit P0, thus avoiding stopping the compressor 61.

[0084] As shown in Figure 8, the control unit 12 then determines whether a predetermined time has elapsed since the start of driving the compressor 61 at the first rotational speed K1 (S23).

[0085] Here, the predetermined time is the time required for the refrigerant to circulate through the heat pump device 6 at least once. The predetermined time may be 1 minute or more, for example, 3 minutes. Note that the predetermined time is short enough to allow the refrigerant to maintain a two-phase state. This operation prevents the refrigerant from becoming liquid and flowing into the compressor 61.

[0086] If the predetermined time has not elapsed (No in S23), the control unit 12 repeats step S23.

[0087] If a predetermined time has elapsed (Yes in S23), the control unit 12 terminates the recovery process and starts the drying process. First, the control unit 12 reduces the opening degree J of the electronic expansion valve 66 from the first opening degree J1 to the threshold J0 (S24).

[0088] As shown in Figure 9, the threshold J0 is smaller than the first opening degree J1. Since foreign matter has already been collected by the recovery process, there is little foreign matter floating in the refrigerant, and even if the opening degree J is reduced, clogging of the electronic expansion valve 66 with foreign matter can be suppressed.

[0089] Next, the control unit 12 increases the rotational speed K of the compressor 61 from the first rotational speed K1 to the threshold K0 (S25).

[0090] In Embodiment 1, the control unit 12 monotonically increases the rotational speed K of the compressor 61 from the first rotational speed K1 to a threshold K0 so as to maintain a state where the rotational speed K of the compressor 61 is above the first rotational speed K1 between the recovery process and the drying process. By setting the rotational speed K of the compressor 61 to the threshold K0, the drying function of the heat pump device 6 can be improved.

[0091] Next, the control unit 12 acquires the temperatures T2 and T3 measured by the second sensor 72 and the third sensor 73 (S26).

[0092] Next, the control unit 12 calculates the intake SH from the temperatures T2 and T3, and controls the opening degree J of the electronic expansion valve 66 and the rotational speed K of the compressor 61 based on the intake SH (S27).

[0093] In step S27, the control unit 12 controls the opening degree J of the electronic expansion valve 66 to be less than or equal to the threshold J0, and controls the rotational speed K of the compressor 61 to be less than or equal to the threshold K0.

[0094] The dryer 1 according to Embodiment 1 can achieve the following effects.

[0095] [effect] The dryer 1 according to Embodiment 1 comprises a storage tank 4 for storing the object to be stored, a heat pump device 6, an air passage member 9 that defines an air passage between the storage tank 4 and the heat pump device 6, and a fan 10 provided on the air passage member 9 for circulating air between the storage tank 4 and the heat pump device 6. The heat pump device 6 connects a compressor 61, a condenser 64, an expansion mechanism 62, and an evaporator 63 with refrigerant piping 65 for circulating the refrigerant. The dryer 1 further comprises a filter 69 for collecting foreign matter contained in the refrigerant flowing through the refrigerant piping 65, and a control unit 12 for controlling the compressor 61 and the expansion mechanism 62. The expansion mechanism 62 has an electronic expansion valve 66 (flow rate adjustment unit) that can change the flow rate of the incoming refrigerant. The control unit 12 is capable of performing a drying process in which the compressor 61 is operated, and a recovery process in which the compressor 61 is operated and the electronic expansion valve 66 is controlled so that a larger flow rate than that in the drying process flows into the expansion mechanism 62.

[0096] With this configuration, during the recovery process, foreign matter suspended in the refrigerant can pass through the electronic expansion valve 66 and be collected by the filter 69. Therefore, during the drying process, the amount of foreign matter suspended in the refrigerant can be reduced, and even if the opening degree J of the electronic expansion valve 66 is reduced, clogging of the electronic expansion valve 66 with foreign matter can be suppressed. Consequently, the reliability of the heat pump device 6 can be improved.

[0097] Furthermore, in the dryer 1 according to Embodiment 1, the control unit 12 performs a recovery process before the drying process.

[0098] With this configuration, by performing the recovery process before the drying process, it is possible to more reliably suppress the clogging of the electronic expansion valve 66 during the drying process.

[0099] Furthermore, in the dryer 1 according to Embodiment 1, during the drying process, the control unit 12 controls the compressor 61 so that the rotation speed K is less than or equal to the threshold K0 (first threshold). During the recovery process, the control unit 12 controls the compressor 61 so that the rotation speed K is less than or equal to the threshold K0.

[0100] With this configuration, by setting a threshold K0, the rise in the high-pressure side pressure P2 during the drying and recovery processes can be suppressed, thereby preventing failure of the compressor 61.

[0101] Furthermore, in the dryer 1 according to Embodiment 1, during the drying process, the control unit 12 controls the electronic expansion valve 66 so that the flow rate is less than or equal to the threshold Q0 (second threshold). During the recovery process, the control unit 12 controls the electronic expansion valve 66 so that the flow rate is greater than the threshold Q0.

[0102] With this configuration, by setting a threshold J0, the refrigerant flow rate can be reduced during the drying process, thereby increasing the pressure P2 on the high-pressure side within a range below the upper limit P0, and improving the drying function of the heat pump device 6. On the other hand, in the recovery process, the rotation speed K is set lower than the threshold K0, and the opening J is set larger than the threshold J0, so even when the state of the heat pump device 6 is not being monitored, the rise in the pressure P2 on the high-pressure side can be suppressed more reliably.

[0103] Furthermore, in the dryer 1 according to Embodiment 1, when the recovery process is completed, the control unit 12 starts the drying process, controls the electronic expansion valve 66 to reduce the flow rate of refrigerant flowing into the expansion mechanism 62, and controls the compressor 61 to increase the rotational speed.

[0104] With this configuration, in the drying process, by decreasing the opening J and increasing the rotation speed K, the differential pressure from the compressor 61 increases, and the operating efficiency of the heat pump device 6 can be improved.

[0105] Furthermore, the dryer 1 according to Embodiment 1 further includes a storage unit 13 that stores default values, and a sensor 73 provided between the compressor 61 and the condenser 64 for measuring the temperature of the refrigerant. In the drying process, the control unit 12 controls the electronic expansion valve 66 based on the measured temperature T3. In the recovery process, the control unit 12 controls the electronic expansion valve 66 based on default values.

[0106] This configuration makes it possible to improve the operating efficiency of the heat pump device 6 during the drying process.

[0107] Furthermore, in the dryer 1 according to Embodiment 1, the electronic expansion valve 66 has a cylindrical portion that defines an opening 75A at its tip, and a needle 76 that has a tapered shape and can be inserted into the opening 75A.

[0108] With this configuration, the flow rate of refrigerant flowing into the expansion mechanism 62 can be easily controlled by controlling the opening degree J.

[0109] This disclosure is not limited to the embodiments described above, and can be implemented in various other forms.

[0110] In Embodiment 1, an example was described in which the control unit 12 controls the opening degree J of the electronic expansion valve 66 to control the flow rate of refrigerant flowing into the expansion mechanism 62, but the invention is not limited to this. The expansion mechanism 62 only needs to be controllable by the control unit 12 and have a mechanism that can change the flow rate of refrigerant flowing into the expansion mechanism 62. Specifically, the expansion mechanism 62 only needs to have a mechanism that can change the flow rate of refrigerant by changing the cross-sectional area of ​​the flow path through which the refrigerant flows. The expansion mechanism 62 may, for example, include a pipe member that defines a flow path and a valve having a groove on the inner surface of a projection that can be inserted into the pipe member.

[0111] The dryer 1 may also have a pressure sensor instead of the temperature sensors 71-73.

[0112] In Embodiment 1, an example was described in which the dryer 1 has a second sensor 72, but the invention is not limited to this. The dryer 1 may have only a first sensor 71 and a third sensor 73.

[0113] In Embodiment 1, an example was described in which the control unit 12 executes the recovery process each time it runs an operation course that includes a drying process, but the invention is not limited to this. The control unit 12 may execute the recovery process at a predetermined timing. The control unit 12 may also execute the recovery process at a timing obtained by referring to the storage unit 13, or at a timing instructed by the user.

[0114] The control unit 12 may perform a recovery process when executing a predetermined operating course. For example, the control unit 12 may perform a recovery process after executing an operating course including a drying process a predetermined number of times. For example, the control unit 12 may perform a recovery process when executing an operating course including a drying process for the first time. For example, the control unit 12 may perform a recovery process when executing an operating course including a drying process for the first time after the dryer 1 has been installed following factory shipment. For example, the control unit 12 may perform a recovery process when executing a dedicated maintenance course. The predetermined operating course does not have to include a drying process. The storage tank 4 may be empty when executing a predetermined operating course.

[0115] In Embodiment 1, an example was described in which the filter 69 is provided in the accumulator 60 between the evaporator 63 and the compressor 61, but the invention is not limited to this. The filter 69 may be provided at any position within the refrigerant piping 65. For example, the filter 69 may be provided in the refrigerant piping 65 between the evaporator 63 and the compressor 61.

[0116] In Embodiment 1, an example was described in which the control unit 12 starts driving the compressor 61 before the start of the recovery process, but the invention is not limited to this. The control unit 12 may also start driving the compressor 61 at the same time as the start of the recovery process.

[0117] In Embodiment 1, an example was described in which the opening degree J in the recovery process is constant at a first opening degree J1 and the rotational speed K is constant at a first rotational speed K1, but the invention is not limited to this. The opening degree J and rotational speed K in the recovery process only need to be greater than the opening degree J and rotational speed K in the drying process, respectively, and may vary.

[0118] In Embodiment 1, an example was described in which the control unit 12 controls the opening degree J and rotation speed K based on the suction SH during the drying process, but the invention is not limited to this. During the drying process, the control unit 12 may control the opening degree J and rotation speed K based on information regarding the temperatures T1 to T3 measured by any of the sensors 71 to 73 or other information. Furthermore, during the recovery process, the control unit 12 may perform a step of acquiring the temperatures T1 to T3 measured by the sensors 71 to 73.

[0119] The dryer in the first embodiment comprises a storage tank for containing an object, a heat pump device connecting a compressor, a condenser, an expansion mechanism, and an evaporator via refrigerant piping for circulating a refrigerant, an air passage member defining an air passage between the storage tank and the heat pump device, a fan provided in the air passage member for circulating air between the storage tank and the heat pump device, a filter for collecting foreign matter contained in the refrigerant flowing through the refrigerant piping, and a control unit for controlling the compressor and the expansion mechanism. The expansion mechanism has a flow rate adjustment unit that can change the flow rate of the incoming refrigerant, and the control unit is capable of performing a drying step in which the compressor is operated, and a recovery step in which the compressor is operated and the flow rate adjustment unit is controlled so that a larger flow rate than that in the drying step flows into the expansion mechanism.

[0120] In the second embodiment, the dryer, as in the first embodiment, has a control unit that performs a recovery process before the drying process.

[0121] In the third embodiment of the dryer, in the dryer of the second embodiment, during the drying process, the control unit controls the compressor so that the rotational speed is less than or equal to a first threshold, and during the recovery process, the control unit controls the compressor so that the rotational speed is less than or equal to a first threshold.

[0122] In the fourth embodiment, as in the dryer of the third embodiment, during the drying process, the control unit controls the flow rate adjustment unit so that the flow rate is less than or equal to the second threshold, and during the recovery process, the control unit controls the flow rate adjustment unit so that the flow rate is greater than the second threshold.

[0123] In the fifth embodiment, as a dryer, in the fourth embodiment, when the recovery process is completed, the control unit starts the drying process, controls the flow rate adjustment unit to reduce the flow rate of refrigerant flowing into the expansion mechanism, and controls the compressor to increase the rotational speed.

[0124] As a dryer in the sixth embodiment, the dryer in any of the first to fifth embodiments further comprises a storage unit that stores a predetermined value, and a sensor provided between the compressor and the condenser for measuring the temperature of the refrigerant, wherein in the drying process, the control unit controls the flow rate adjustment unit based on the measured temperature, and in the recovery process, the control unit controls the flow rate adjustment unit based on a predetermined value.

[0125] In the seventh embodiment, as a dryer in any of the first to sixth embodiments, the flow rate adjustment unit has a cylindrical portion with an opening defined at its tip and a needle that has a tapered shape and can be inserted into the opening.

[0126] While this disclosure is adequately described in relation to preferred embodiments with reference to the accompanying drawings, various modifications and alterations will be obvious to those skilled in the art. Such modifications and alterations should be understood to be included within the scope of the invention as defined by the appended claims. [Industrial applicability]

[0127] The dryer of this disclosure can improve the reliability of the heat pump system and is therefore useful as a household clothes dryer, a commercial clothes dryer, any type of washer-dryer (e.g., a household drum-type washer-dryer, a top-loading washer-dryer), and other garment processing machines with drying functions. [Explanation of Symbols]

[0128] 1 Dryer 2 cabinets 3 Outer tank 4 Storage tank 6. Heat pump system 8 cases 9. Airflow members 10 Fans 61 Compressor 62 Expansion Mechanism 63 Evaporator 64 Condenser 65 Refrigerant piping 66 Electronic expansion valve 71 First Sensor 72. Second Sensor 73 Third Sensor

Claims

1. A storage tank for containing the object, A heat pump system is formed by circulating a refrigerant through refrigerant piping, connecting a compressor, condenser, expansion mechanism, and evaporator. An air passage member that defines an air passage between the storage tank and the heat pump device, A fan is provided in the air passage member to circulate air between the containment tank and the heat pump device, A filter for collecting foreign matter contained in the refrigerant flowing through the aforementioned refrigerant piping, The system comprises a control unit that controls the compressor and the expansion mechanism, The expansion mechanism has a flow rate adjustment unit that can change the flow rate of the incoming refrigerant, A dryer having a control unit capable of performing a drying step of operating the compressor and a recovery step of operating the compressor and controlling the flow rate adjustment unit so that a larger flow rate than that of the drying step flows into the expansion mechanism.

2. The dryer according to claim 1, wherein the control unit performs the recovery step before the drying step.

3. In the drying process, the control unit controls the compressor so that the rotation speed is less than or equal to a first threshold. In the recovery step, the control unit controls the compressor so that the rotation speed is less than or equal to the first threshold, as described in claim 2.

4. In the drying process, the control unit controls the flow rate adjustment unit so that the flow rate is less than or equal to the second threshold. In the recovery step, the control unit controls the flow rate adjustment unit so that the flow rate becomes greater than the second threshold, as described in claim 3.

5. The dryer according to claim 4, wherein the control unit, upon completion of the recovery process, starts the drying process, controls the flow rate adjustment unit to reduce the flow rate of refrigerant flowing into the expansion mechanism, and controls the compressor to increase the rotational speed.

6. A memory unit that stores default values, The system further includes a sensor provided between the compressor and the condenser for measuring the temperature of the refrigerant, In the drying process, the control unit controls the flow rate adjustment unit based on the measured temperature. In the recovery step, the control unit controls the flow rate adjustment unit based on the predetermined value, as described in any one of claims 1 to 5.

7. The dryer according to any one of claims 1 to 5, wherein the flow rate adjustment unit comprises a cylindrical portion defining an opening at its tip and a needle having a tapered shape and being insertable into the opening.

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