Refrigeration cycle equipment

Abstract

To provide a refrigeration cycle system that can suppress malfunctions of the four-way valve at low ambient temperatures. [Solution] The refrigeration cycle device comprises a four-way valve and a control unit. The four-way valve has a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, and switches the direction of flow of the refrigerant that is circulated by the compressor in a refrigerant circuit and connected to the refrigerant circuit. The control unit controls the compressor and switches between heating operation, in which the refrigerant is circulated in a heating cycle, cooling operation, in which the refrigerant is circulated in a cooling cycle with the opposite flow direction to the heating cycle, and defrosting operation, in which frost has formed on the outdoor heat exchanger due to heating operation is removed in the cooling cycle, by switching the four-way valve. When the control unit receives an operation stop signal and is performing defrosting operation, it stops the compressor after performing heating operation for a predetermined time or longer after the completion of defrosting operation.

Description

Technical Field

[0001] The present invention relates to a refrigeration cycle device.

Background Art

[0002] A refrigeration cycle device includes an indoor unit having an indoor heat exchanger, and an outdoor unit having an outdoor heat exchanger, a compressor, and a four-way valve. Further, the indoor heat exchanger and the outdoor heat exchanger are connected by a refrigerant circuit through which a refrigerant flows. The refrigeration cycle device can perform a cooling operation, a heating operation, or a defrosting operation by switching the flow direction of the refrigerant compressed by the compressor with the four-way valve.

[0003] However, when the four-way valve fails to operate normally due to an abnormality such as foreign matter contamination or clogging, the refrigeration cycle device may not be able to perform a correct cooling operation, heating operation, or defrosting operation. Therefore, in the above refrigeration cycle device, a technique has been proposed to reduce the occurrence of a malfunction of the four-way valve due to a malfunction of the plunger movement caused by foreign matter or the like by extending the energization time to the four-way valve during a malfunction (switching malfunction) (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the four-way valve switches the refrigerant flow path by moving the position of the slide valve using the high and low pressure difference of the refrigerant. However, when the outside air temperature is low, it is known that the refrigerant density decreases and the pressure on the high-pressure side of the refrigerant becomes difficult to rise, so the high and low pressure difference becomes small and the slide valve becomes difficult to move. The technology disclosed in Patent Document 1 above does not adequately consider malfunctions of the four-way valve caused by a decrease in the high-low pressure difference, and there is a possibility that the four-way valve may malfunction at low ambient temperatures.

[0006] This invention addresses a previously unresolved problem and aims to provide a refrigeration cycle device that can suppress malfunctions of the four-way valve at low ambient temperatures. [Means for solving the problem]

[0007] To achieve the above objective, according to one aspect of the present invention, a refrigeration cycle device is provided which includes a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, and comprises a refrigerant circuit through which a refrigerant compressed by the compressor circulates, a four-way valve connected to the refrigerant circuit and switching the direction of flow of the refrigerant circulating in the refrigerant circuit, and a control unit that controls the compressor and switches between a heating operation in which the refrigerant is circulated in a heating cycle, a cooling operation in which the refrigerant is circulated in a cooling cycle with a flow direction opposite to that of the heating cycle, and a defrosting operation in which frost has formed on the outdoor heat exchanger due to the heating operation is defrosted in the cooling cycle, by switching the four-way valve, wherein if the control unit is performing a defrosting operation when it receives an operation stop signal, it stops the compressor after performing a heating operation for a predetermined time or longer after the completion of the defrosting operation. [Effects of the Invention]

[0008] According to one aspect of the present invention, a refrigeration cycle device can be obtained that can suppress malfunctions of the four-way valve at low ambient temperatures. [Brief explanation of the drawing]

[0009] [Figure 1] This is a refrigerant circuit diagram showing an overview of a refrigeration cycle device according to the first embodiment of this disclosure. [Figure 2] This is a first diagram showing the functional configuration of a four-way valve according to the first embodiment of the present disclosure. [Figure 3] This is a second diagram showing the functional configuration of a four-way valve according to the first embodiment of this disclosure. [Figure 4]This is a block diagram showing the functional configuration of a control device according to the first embodiment of the present disclosure. [Figure 5] This figure shows the slide valve of the four-way valve in the first embodiment of this disclosure stopped in the intermediate position. [Figure 6] This is a timing chart illustrating an example of the operation of a control device according to the first embodiment of this disclosure. [Figure 7] This is a flowchart showing the control processing procedure of a control device according to the first embodiment of the present disclosure. [Figure 8] This block diagram shows a functional configuration of a control device according to a second embodiment of the present disclosure. [Figure 9] This is a flowchart showing the control processing procedure of a control device according to a second embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] Next, embodiments of the present invention will be described with reference to the drawings. In the following drawings, identical or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Furthermore, the embodiments described below illustrate devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0011] <First Embodiment> (Overall structure) Figure 1 is a refrigerant circuit diagram showing an overview of a refrigeration cycle system according to the first embodiment of this disclosure. As shown in Figure 1, the refrigeration cycle device 100 according to the first embodiment of this disclosure comprises a refrigerant circuit 1 including a compressor 2, an indoor heat exchanger 3, an outdoor heat exchanger 4, an expansion valve 5, a four-way valve 6, and refrigerant piping 7 connecting them, and a control device 20 for controlling the refrigerant circuit 1. For example, the indoor heat exchanger 3 is provided in the indoor unit 8, and the compressor 2, outdoor heat exchanger 4, expansion valve 5, and four-way valve 6 are provided in the outdoor unit 9. The indoor heat exchanger 3 is also provided with an indoor heat exchanger temperature sensor 11 for detecting the temperature of the indoor heat exchanger 3.

[0012] The outdoor unit 9 is also equipped with an outside air temperature sensor 12, an outdoor fan 13, and an outdoor heat exchanger temperature sensor 16. The outside air temperature sensor 12 uses, for example, a thermistor and outputs a voltage value that changes according to the outside air temperature as the outside air temperature detection value (hereinafter referred to as outside air temperature) to the control device 20A (an example of a control unit). The outdoor fan 13 is driven by a motor (not shown) to take in outside air into the outdoor unit 9 and generate an airflow to release the outside air that has exchanged heat with the refrigerant in the outdoor heat exchanger 4 to the outside of the outdoor unit 9. The outdoor heat exchanger temperature sensor 16 detects the temperature of the outdoor heat exchanger 4.

[0013] Furthermore, the indoor unit 8 is equipped with an indoor fan 14 and a room temperature sensor 15. The indoor fan 14 is driven by a motor (not shown) to draw in indoor air into the indoor unit 8 and generate an airflow for releasing the air that has exchanged heat with the refrigerant in the indoor heat exchanger 3 back into the room. The room temperature sensor 15 uses, for example, a thermistor and outputs a voltage value that changes according to the indoor temperature as a room temperature detection value to the control device 20A. Compressor 2 compresses the refrigerant and discharges the high-temperature, high-pressure refrigerant after compression into the refrigerant piping 7 (hereinafter referred to as 7-1). The high-pressure refrigerant compressed by compressor 2 flows into port 6a of the four-way valve 6 via the refrigerant piping 7-1.

[0014] In the heating operation, the control device 20A controls the four-way valve 6 to connect the port 6a and the port 6b of the four-way valve 6 and connect the port 6c and the port 6d. Thereby, in the heating operation, the refrigerant flows in the direction of arrow A1. That is, the high-temperature and high-pressure refrigerant is supplied to the indoor heat exchanger 3 via the four-way valve 6. The refrigerant dissipates heat and condenses in the indoor heat exchanger 3. Further, the refrigerant condensed in the indoor heat exchanger 3 is depressurized by the expansion valve 5 and becomes a low-pressure refrigerant. The low-pressure refrigerant is supplied to the outdoor heat exchanger 4 and evaporates, for example, by absorbing heat from the outside air. That is, in the heating operation, the indoor heat exchanger 3 functions as a condenser, and the outdoor heat exchanger 4 functions as an evaporator. Further, the refrigerant evaporated in the outdoor heat exchanger 4 is sucked into the compressor 2 via the four-way valve 6. The compressor 2 recompresses the low-pressure refrigerant and discharges a high-temperature and high-pressure refrigerant.

[0015] On the other hand, in the cooling operation, the control device 20A controls the four-way valve 6 to connect the port 6a and the port 6d of the four-way valve 6 and connect the port 6b and the port 6c. Thereby, in the cooling operation, the refrigerant flows in the direction of arrow A2. That is, the high-temperature and high-pressure refrigerant is supplied to the outdoor heat exchanger 4 via the four-way valve 6, dissipates heat to the outside air, and condenses. Further, the refrigerant condensed in the outdoor heat exchanger 4 is depressurized by the expansion valve 5 and supplied to the indoor heat exchanger 3. In the indoor heat exchanger 3, the refrigerant evaporates, for example, by absorbing heat from the indoor air. That is, in the cooling operation, the outdoor heat exchanger 4 functions as a condenser, and the indoor heat exchanger 3 functions as an evaporator. Further, the refrigerant evaporated in the indoor heat exchanger 3 is sucked into the compressor 2 via the four-way valve 6. The compressor 2 recompresses the low-pressure refrigerant and discharges a high-temperature and high-pressure refrigerant.

[0016] The refrigeration cycle device 100 performs heating or cooling by repeating the above process to circulate the refrigerant. The control device 20A switches between the heating operation and the cooling operation by controlling the four-way valve 6. Further, the control device 20A adjusts the rotational speed of the compressor 2 based on the difference between the temperature measured by the room temperature sensor 15 and the set temperature set by the user so that the indoor temperature becomes the set temperature, and executes the heating operation or the cooling operation.

[0017] Furthermore, when heating is performed in an environment with low outside temperatures, frost may form on the outdoor heat exchanger 4. To prevent a decrease in heating capacity due to frost formation, the refrigeration cycle device 100 performs a defrosting operation to remove frost from the outdoor heat exchanger 4. During the defrosting operation, the control device 20A switches the four-way valve 6 to set the direction of refrigerant flow to the same direction as during cooling operation (arrow A2 in Figure 1). This supplies high-temperature, high-pressure refrigerant to the outdoor heat exchanger 4 to defrost it.

[0018] (Functional configuration of a four-way valve) Figure 2 is a first diagram showing the functional configuration of a four-way valve according to the first embodiment of the present disclosure. Figure 3 is a second diagram showing the functional configuration of a four-way valve according to the first embodiment of this disclosure. As shown in Figures 2 and 3, the four-way valve 6 has a main valve 60 that switches the direction of flow of the refrigerant and a pilot valve 64. The four-way valve 6 according to the first embodiment of this disclosure is an AC (alternating current) type four-way valve.

[0019] The main valve 60 is formed in a cylindrical shape extending in the direction of the axis O1 and has a slide valve 61 and a pair of pistons 62 inside. The pair of pistons 62 are arranged to face each other on one side and the other side in the direction of the axis O1, dividing the inside of the main valve 60 into a region R1 on one side in the direction of the axis O1 (left side in Figures 2 and 3) and a region R2 on the other side (right side in Figures 2 and 3). The pistons 62 are connected to the slide valve 61 by a connecting member 63 and move the slide valve 61 by moving to one side or the other side in the direction of the axis O1 due to the pressure of the refrigerant introduced into the main valve 60 from the pilot valve 64 described later. As the slide valve 61 moves in conjunction with the movement of the pistons 62, the main valve 60 selectively connects port 6a, into which high-pressure refrigerant from the compressor 2 is introduced, and either port 6b or port 6d, into which high-pressure refrigerant is discharged.

[0020] The pilot valve 64 is formed in a cylindrical shape extending in the direction of the axis O2, and contains a pilot valve body 65, a solenoid 66, a plunger 67, a coil spring 68, and a permanent magnet 69. A conduit P1 branching from the refrigerant piping 7-1 that connects the compressor 2 and port 6a of the four-way valve 6 (main valve 60) is connected to one end of the pilot valve 64 in the direction of the axis O2, and high-pressure refrigerant is introduced from this conduit P1. In addition, the pilot valve 64 is connected to a conduit P2 that communicates with region R1 of the main valve 60, a conduit P2 that communicates with region R2, and a conduit P3 branching from the refrigerant piping 7 (hereinafter referred to as 7-2) that connects to port 6c of the main valve 60.

[0021] The plunger 67 is housed radially inward of the solenoid 66 and is biased by the coil spring 68 toward one side in the direction of the axis O2 (left side in Figure 3). When heating operation is started, current is applied to the solenoid 66. As a result, as shown in Figure 2, the plunger 67 is attracted by the solenoid 66 toward the other side in the direction of axis O2 (direction of arrow B1 in Figure 2) and is held by the permanent magnet 69.

[0022] At this time, the pilot valve body 65 moves toward the other side in the direction of axis O2 (direction of arrow B1 in Figure 2) as the plunger 67 moves. As a result, conduits P3 and P4 are connected inside the pilot valve body 65, and conduits P1 and P2 are connected outside. The high-pressure refrigerant introduced into the pilot valve 64 from conduit P1 flows into region R1 on the other side of the main valve 60 from conduit P2. At this time, region R1 is at a higher pressure than region R2, so the piston 62 of the main valve 60 moves toward the other side in the direction of axis O1 (direction of arrow C1 in Figure 2). As a result, ports 6c and 6d are connected inside the slide valve 61 which has moved with the piston 62, and ports 6a and 6b are connected via region R3 between the pair of pistons. In this way, the high-pressure refrigerant supplied from the compressor 2 is supplied to the indoor heat exchanger 3.

[0023] On the other hand, when cooling operation is started, no current is applied to the solenoid 66. In this case, as shown in Figure 3, the plunger 67 is pushed away from the permanent magnet 69 by the solenoid 66 and biased by the coil spring 68 toward one side in the direction of axis O2 (direction of arrow B2 in Figure 3).

[0024] At this time, the pilot valve body 65 moves toward one side in the direction of axis O2 (direction of arrow B2 in Figure 2) as the plunger 67 moves. As a result, conduits P2 and P3 are connected inside the pilot valve body 65, and conduits P1 and P4 are connected outside. The high-pressure refrigerant introduced into the pilot valve 64 from conduit P1 flows into region R2 on the other side of the main valve 60 from conduit P4. At this time, region R2 has a higher pressure than region R1, so the piston 62 of the main valve 60 moves toward one side in the direction of axis O1 (direction of arrow C2 in Figure 3). As a result, ports 6b and 6c are connected inside the slide valve 61 which has moved with the piston 62, and ports 6a and 6d are connected via region R3 between the pair of pistons. In this way, the high-pressure refrigerant supplied from the compressor 2 is supplied to the outdoor heat exchanger 4. Furthermore, when defrosting is initiated, the four-way valve 6 operates in the same manner as during cooling operation.

[0025] (Functional configuration of the control unit) Figure 4 is a block diagram showing the functional configuration of a control device according to the first embodiment of this disclosure. The control device 20A according to the first embodiment of this disclosure includes a temperature acquisition unit 200, an operating mode determination unit 201, a four-way valve control unit 202, and a storage unit 203.

[0026] The temperature acquisition unit 200 acquires the temperature of the indoor heat exchanger 3 from the indoor heat exchanger temperature sensor 11 and the outside air temperature from the outside air temperature sensor 12. In addition, the temperature acquisition unit 200 acquires the indoor temperature from the room temperature sensor 15 and the temperature of the outdoor heat exchanger 4 from the outdoor heat exchanger temperature sensor 16. The operating mode determination unit 201 determines the current operating mode of the refrigeration cycle unit 100. The operating mode of the refrigeration cycle unit 100 is one of the following: heating operation mode, cooling operation mode, or defrosting operation mode.

[0027] The four-way valve control unit 202 switches the direction of refrigerant flow in the refrigerant circuit 1 by selectively energizing or de-energizing the four-way valve 6. The memory unit 203 stores various data used, acquired, and generated in the processing of each part of the control device 20A. The memory unit 203 also stores a control program that performs the control according to the first embodiment. The control device 20A operates according to the control program stored in the memory unit 203 when the refrigeration cycle device 100 is in heating or cooling operation.

[0028] In this first embodiment of the refrigeration cycle device 100, a user-operable remote controller (not shown) is provided, and when the user operates the remote controller to start or stop the heating or cooling operation of the refrigeration cycle device 100, the control device 20A executes the start or stop of the heating or cooling operation of the refrigeration cycle device 100.

[0029] (Regarding the behavior when the slide valve of the four-way valve in the first embodiment of this disclosure stops in the intermediate position) Figure 5 shows the state in which the slide valve of the four-way valve in the first embodiment of this disclosure is stopped in the intermediate position. The slide valve 61 of the four-way valve 6 may move from its stopped position in the cooling position to an intermediate position when heating is started, i.e., when heating operation begins, due to a defrosting operation performed before the operation was stopped. In this case, high-pressure refrigerant from the compressor 2 flows to ports 6b and 6d as shown by arrow D1 in Figure 5 (shown as a solid line in Figure 5), so that almost no refrigerant flows into port 6c, and the refrigerant does not circulate sufficiently in the refrigerant circuit 1.

[0030] As a result, when less refrigerant flows out of port 6c and port 6c becomes close to a vacuum, the low pressure decreases. On the other hand, when a small amount of compressed gas (high-pressure gas) is drawn in from the circled parts E1 and E2 in Figure 5 and flows into port 6c as shown by arrow D2 in Figure 5 (shown as a dashed line in Figure 5), operation continues in a state where the high-low pressure difference is small, and the slide valve 61 remains stopped in the intermediate position. Furthermore, this phenomenon, in which the slide valve 61 stops in an intermediate position, is more likely to occur as the size of the four-way valve 6 increases relative to the exhaust volume of the compressor 2 (i.e., the amount of refrigerant circulated is less relative to the size of the slide valve 61).

[0031] (Solution according to the first embodiment of this disclosure) Therefore, in the first embodiment of this disclosure, if the control device 20A receives an operation stop signal while performing defrosting operation, it stops the compressor 2 after performing heating operation for a predetermined time after the completion of defrosting operation. Figure 6 is a timing chart illustrating an example of the operation of the control device 20A according to the first embodiment of this disclosure. In Figure 6, the vertical axis represents the rotational speed (compressor Hz) of the compressor 2 and the polarity of the four-way valve 6, and the horizontal axis represents time.

[0032] At time t11, when the control device 20A receives a stop signal from the remote controller held by the user, it terminates the heating operation. If the control device 20A determines that defrosting is necessary, at time t12, it switches the four-way valve 6 to the cooling side and performs defrosting in the cooling cycle for an operating period tm1 until the defrosting operation is completed at time t13. Here, the operating period tm1 is, for example, 15 minutes, or the time until the temperature of the outdoor heat exchanger 4 reaches, for example, 16°C or higher.

[0033] When the defrosting operation is completed, the control device 20A switches the four-way valve 6 to the heating side at time t14 and starts the heating operation. Then, after performing the heating operation for an operating period tm2 from time t14 to time t15, it terminates. This heating operation (hereinafter referred to as pre-stop heating operation) moves the position of the slide valve 61 to the heating side. Here, the operating period tm2 is, for example, 60 seconds, or the time it takes for the slide valve 61 to move completely to the heating position. Furthermore, the rotational speed of the compressor 2 during the pre-stop heating operation should be such that there is a high-low pressure difference sufficient to move the slide valve 61 to the heating position. In other words, the rotational speed of the compressor 2 during the pre-stop heating operation can be lower than that during normal heating operation and defrosting operation.

[0034] Figure 7 is a flowchart showing the control processing procedure of the control device 20A according to the first embodiment of this disclosure. First, the control device 20A determines whether or not it has received a stop signal from the remote controller held by the user during heating operation (step ST7a). If it determines that it has not received a stop signal (step ST7a: No), the control device 20A continues the process of determining whether or not it has received a stop signal in step ST7a. At this time, the control device 20A monitors the current operating mode using the operating mode determination unit 201.

[0035] On the other hand, if the control device 20A determines that it has received a stop operation signal (step ST7a: Yes), the temperature acquisition unit 200 and the operation mode determination unit 201 determine whether or not defrosting operation is necessary (step ST7b). The conditions under which defrosting operation is necessary are as follows. (1) When a stop signal is received during heating operation, if the cumulative operating time of heating operation is equal to or greater than a predetermined time (e.g., 30 minutes), and the continuous operating time is equal to or greater than a predetermined time (e.g., 10 minutes), and the temperature of the outdoor heat exchanger 4 is equal to or less than a predetermined temperature (e.g., -4°C) (2) When a stop signal is received during defrosting operation, and the time of defrosting operation is less than the operating period tm1 from time t12 to time t13 as shown in Figure 6.

[0036] If it is determined that defrosting is necessary (step ST7b: Yes), the control device 20A uses the temperature acquisition unit 200 to determine whether the outside air temperature read from the outside air temperature sensor 12 is at a predetermined temperature, for example, -15°C or higher (step ST7c). If the device determines that the temperature is below a predetermined level (step ST7c: Yes), the control device 20A switches the four-way valve 6 to the cooling side via the four-way valve control unit 202 and performs defrosting (step ST7d), and terminates the defrosting operation by the time t13 shown in Figure 6 (step ST7e).

[0037] Then, the control device 20A, using the four-way valve control unit 202, switches the four-way valve 6 to the heating side and performs heating operation for an operating period tm2 or longer from time t14 to time t15 as shown in Figure 6 (step ST7f), and after time t15 has elapsed, stops the compressor 2 (step ST7g).

[0038] On the other hand, if it is determined in step ST7c that the temperature is above a predetermined level (step ST7c: No), the control device 20A switches the four-way valve 6 to the cooling side using the four-way valve control unit 202 and performs defrosting (step ST7h). The defrosting operation is completed by the time t13 shown in Figure 6 (step ST7i), and the process proceeds to step ST7g without performing pre-stop heating operation, stopping the compressor 2. Furthermore, if the control device 20A determines that defrosting is not necessary during the process in step ST7b (step ST7b: No), it proceeds to the process in step ST7i and stops the compressor 2.

[0039] <Effects and Effects of the First Embodiment> As described above, according to the first embodiment, by performing a pre-stop heating operation when the unit is stopped, the four-way valve 6 can be switched to the heating position in advance, thereby suppressing switching failures when the heating unit is restarted. Furthermore, the first embodiment of this disclosure is particularly effective when a four-way valve 6 of a size larger than the exhaust volume of the compressor 2 is selected. Furthermore, according to the first embodiment, when the outside air temperature is above a predetermined temperature and the possibility of a switching failure is low, the time until operation stops can be shortened by not performing heating operation, thereby contributing to energy saving.

[0040] <Second Embodiment> A second embodiment of this disclosure relates to indoor comfort. The refrigeration cycle device 100 according to the first embodiment is applicable to the refrigeration cycle device according to the second embodiment. Hereinafter, an example of a control device for the refrigeration cycle device according to the second embodiment to which the refrigeration cycle device 100 according to the first embodiment is applied will be described.

[0041] Figure 8 is a block diagram showing the functional configuration of the control device 20B according to the second embodiment of the present disclosure. In Figure 8, the same parts as in Figure 4 are denoted by the same reference numerals and detailed descriptions are omitted. The control device 20B includes an indoor fan control unit 204. The indoor fan control unit 204 controls the driving or stopping of the indoor fan 14.

[0042] Figure 9 is a flowchart showing the control processing procedure of the control device 20B according to the second embodiment of this disclosure. First, the control device 20B determines whether or not it has received a stop signal from the remote controller held by the user during heating operation (step ST9a). If it determines that it has not received a stop signal (step ST9a: No), the control device 20B continues the process of determining whether or not it has received a stop signal in step ST9a.

[0043] On the other hand, if it determines that a stop operation signal has been received (step ST9a: Yes), the control device 20B determines whether or not defrosting operation is necessary using the temperature acquisition unit 200 and the operation mode determination unit 201 (step ST9b). The conditions under which defrosting operation is necessary are the same as those in the first embodiment described above. If it is determined that defrosting is necessary (step ST9b: Yes), the control device 20B uses the temperature acquisition unit 200 to determine whether the outside air temperature read from the outside air temperature sensor 12 is at a predetermined temperature, for example, -15°C or higher (step ST9c).

[0044] If the device determines that the temperature is below a predetermined level (step ST9c: Yes), the control device 20B switches the four-way valve 6 to the cooling side using the four-way valve control unit 202 to perform defrosting (step ST9d), and drives the indoor fan 14 using the indoor fan control unit 204 (step ST9e). Then, the control device 20B finishes the defrosting operation by the time t13 shown in Figure 6 (step ST9f), and stops the indoor fan 14 using the indoor fan control unit 204 (step ST9g).

[0045] Then, the control device 20B, using the four-way valve control unit 202, switches the four-way valve 6 to the heating side and performs pre-stop heating operation for the operating period tm2 from time t14 to time t15 as shown in Figure 6 (step ST9h), and after time t15 has elapsed, stops the compressor 2 (step ST9i). During this operating period tm2, the control device 20B, using the indoor fan control unit 204, maintains the indoor fan 14 in a stopped state so as not to drive the indoor fan 14.

[0046] On the other hand, if the device determines in step ST9c that the temperature is above a predetermined level (step ST9c: No), the control device 20B switches the four-way valve 6 to the cooling side using the four-way valve control unit 202 to perform defrosting (step ST9j), and drives the indoor fan 14 using the indoor fan control unit 204 (step ST9k). The control device 20B then finishes the defrosting operation by the time t13 shown in Figure 6 (step ST9l), stops the indoor fan 14 using the indoor fan control unit 204 (step ST9m), and proceeds to the process in step ST9i without performing pre-stop heating operation to stop the compressor 2. Furthermore, if the control device 20B determines that defrosting is not necessary during the process of step ST9b (step ST9b: No), it proceeds to the process of step ST9i and stops the compressor 2.

[0047] <Effects and Effects of the Second Embodiment> As described above, the second embodiment provides the same effects as the first embodiment, and by driving the indoor fan 14 while the defrosting operation is being performed, the outdoor heat exchanger 4 can be defrosted efficiently. Furthermore, according to the second embodiment, after the user operates the remote controller to instruct the operation to stop, the indoor fan control unit 204 maintains the indoor fan 14 in a stopped state, preventing air from being blown into the room from the indoor fan 14, thereby suppressing a decrease in comfort.

[0048] <Other Embodiments> As described above, the present invention has been described by first and second embodiments, but the descriptions and drawings that constitute part of this disclosure should not be understood as limiting the present invention. Those skilled in the art will understand that various alternative embodiments, examples, and operational techniques can be included in the present invention by understanding the spirit of the technical content disclosed in the above embodiments. Furthermore, the configurations disclosed in the first and second embodiments can be combined as appropriate, within the bounds of consistency. For example, configurations disclosed in multiple different embodiments may be combined, or configurations disclosed in multiple different modifications of the same embodiment may be combined. [Explanation of Symbols]

[0049] 1. Refrigerant circuit 2 Compressor 3 Indoor heat exchanger 4 Outdoor heat exchanger 5. Expansion valve 6. Four-way valve Ports 6a, 6b, 6c, and 6d 7,7-1,7-2 Refrigerant piping 8 Indoor unit 9 Outdoor unit 11. Indoor heat exchanger temperature sensor 12. Outdoor temperature sensor 13 Outdoor fan 14 Indoor fan 15. Room temperature sensor 16. Outdoor heat exchanger temperature sensor 20A, 20B control unit 60 Main Officer 61 Slide valve 62 pistons 63 Connecting member 64 Pilot valve 65 Pilot valve body 66 Solenoid 67 Plunger 68 Coil spring 69 Permanent Magnets 100 Refrigeration cycle equipment 200 Temperature acquisition section 201 Operating mode determination unit 202 Four-way valve control unit 203 Storage section 204 Indoor Fan Control Unit P1,P2,P3,P4 conduit R1,R2 area

Claims

1. A refrigerant circuit comprising a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, through which the refrigerant compressed by the compressor circulates, A four-way valve connected to the refrigerant circuit, which switches the direction of flow of the refrigerant circulating in the refrigerant circuit, A control unit that controls the compressor and switches between a heating operation in which the refrigerant is circulated in a heating cycle, a cooling operation in which the refrigerant is circulated in a cooling cycle with the opposite flow direction to the heating cycle, and a defrosting operation in which the outdoor heat exchanger, which has accumulated frost due to the heating operation, is defrosted in the cooling cycle, by switching the four-way valve. Equipped with, When the control unit receives a stop signal and is performing the defrosting operation, it stops the compressor after performing the heating operation for a predetermined time or longer after the defrosting operation is completed. Refrigeration cycle device.

2. Equipped with an outside air temperature sensor that detects the outside air temperature, The refrigeration cycle apparatus according to claim 1, wherein when the control unit receives the operation stop signal, if the outside air temperature detected by the outside air temperature sensor is above a predetermined temperature, it stops the compressor without performing the heating operation after the defrosting operation is completed.

3. An indoor fan that takes in indoor air and releases the air, which has exchanged heat with the refrigerant by the indoor heat exchanger, back into the room. A fan control unit that controls the indoor fan, Equipped with, The refrigeration cycle apparatus according to claim 1, wherein the fan control unit drives the indoor fan while the defrosting operation is being performed.

4. The refrigeration cycle apparatus according to claim 3, wherein the fan control unit maintains the indoor fan in a stopped state when the heating operation is performed for a predetermined time or longer after the completion of the defrosting operation.

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