Air conditioner

Abstract

To provide an air conditioner capable of being stably operated even while heating operation is stopped and of securing high habitability.SOLUTION: A control unit of an air conditioner includes: a reception part for receiving an operation stop command; a reading part for reading an outside air temperature, an amount of sealed refrigerant, and a predetermined coolant amount threshold when the operation stop command is received; a coolant amount acquisition part for acquiring indoor side coolant amount for each elapsed time on the basis of a table including a ratio of a predetermined time from operation stop and prediction value of the indoor side coolant amount at the time passed; a comparison part comparing the indoor side coolant amount with a coolant amount threshold; and a determination part which determines whether or not cooling operation for transferring a coolant remaining on the indoor heat exchanger side to an outdoor heat exchanger side on the basis of a comparison result by the comparison part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to air conditioning systems. [Background technology]

[0002] If the concentration of flammable refrigerant leaking from an air conditioner exceeds the minimum combustion concentration, there is a risk of a fire. Considering the risk of highly flammable refrigerant leaking into the room, a method is known in which the refrigerant circuits on the indoor side and the outdoor side are shut off when the air conditioner is stopped, thereby reducing the amount of refrigerant that may leak into the room. As a specific technique for this purpose, as described in Patent Document 1 below, for example, a method has been adopted in which cooling operation is performed for a certain period of time after heating operation is stopped, and the refrigerant circuits on the indoor side and the outdoor side are shut off in a state in which as much of the refrigerant as possible is moved to the outdoor side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7159748 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the air in the room that has been warmed by the heating operation is cooled again by the cooling operation, which causes a problem that the livability of the room is impaired when the air conditioner is used.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an air conditioner that can be operated stably even when heating operation is stopped and that can ensure high livability. [Means for solving the problem]

[0006] In order to solve the above problems, an air conditioner according to the present disclosure includes an indoor heat exchanger, an outdoor heat exchanger, a gas pipe connecting the indoor heat exchanger and the outdoor heat exchanger and through which a gas-phase refrigerant flows, a compressor arranged on the gas pipe, a liquid pipe connecting the indoor heat exchanger and the outdoor heat exchanger and through which a liquid-phase or two-phase gas-liquid refrigerant flows and which forms a circulation circuit together with the gas pipe, an expansion valve provided on the liquid pipe, a four-way valve that switches the flow direction of the refrigerant between cooling operation and heating operation, shut-off valves provided on the gas pipe and on the liquid pipe, a temperature measurement unit that measures an outside air temperature, and a control device. The control device has a receiving unit that receives an operation stop command, a reading unit that reads the outside air temperature, the amount of sealed refrigerant, and a predetermined refrigerant amount threshold when the operation stop command is received, a refrigerant amount acquisition unit that acquires the indoor refrigerant amount for each elapsed time based on a table including a ratio between a predetermined time from the operation stop and a predicted value of the indoor refrigerant amount at the time the predetermined time has elapsed, a comparison unit that compares the indoor refrigerant amount with the refrigerant amount threshold, and a determination unit that determines whether to perform cooling operation to transfer the refrigerant remaining on the indoor heat exchanger side to the outdoor heat exchanger side based on a comparison result by the comparison unit. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an air conditioner that can be stably operated even when heating operation is stopped and that can ensure high habitability. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a refrigerant circuit of an air conditioner according to an embodiment of the present disclosure, illustrating a state during heating operation. [Diagram 2] FIG. 2 is a functional block diagram of a control device according to an embodiment of the present disclosure. [Diagram 3] 13 is an example of a table including a ratio of the time since the operation of an air conditioner according to an embodiment of the present disclosure has been stopped to a predicted value of the amount of indoor refrigerant at the time the time has elapsed. [Figure 4] 5 is a flowchart showing a processing flow of a control device according to an embodiment of the present disclosure. [Diagram 5] FIG. 1 is a schematic diagram showing a refrigerant circuit of an air conditioner according to an embodiment of the present disclosure, illustrating a state during cooling operation. [Figure 6] FIG. 2 is a hardware configuration diagram of a control device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Air Conditioner Configuration) An air conditioner 1 according to an embodiment of the present disclosure will be described below with reference to Fig. 1 to Fig. 8. As shown in Fig. 1, the air conditioner 1 includes a refrigeration cycle circuit 10, a first operating valve 20, a second operating valve 30, a temperature measuring unit 41, a leak detection sensor 42, and a control device 50. The first operating valve 20 and the second operating valve 30 may be collectively referred to as "shutoff valves."

[0010] (Refrigeration cycle circuit 10) The refrigeration cycle circuit 10 includes an indoor heat exchanger 11, an outdoor heat exchanger 12, a gas pipe 13, a compressor 14, a liquid pipe 15, an expansion valve 16, and a four-way valve (not shown).

[0011] The indoor heat exchanger 11 exchanges heat between the indoor air and the refrigerant. The indoor heat exchanger 11 is, for example, a fin-and-tube type or plate type heat exchanger, and the refrigerant flows inside. Although not shown in the figure, it is desirable to provide the indoor heat exchanger 11 with a fan for compressing air into the room.

[0012] The outdoor heat exchanger 12 exchanges heat between the outdoor air and the refrigerant. The outdoor heat exchanger 12 is, for example, a fin-and-tube type or plate type heat exchanger, similar to the indoor heat exchanger 11, and a refrigerant flows inside. Although not shown, it is preferable that the outdoor heat exchanger 12 is provided with a fan for compressing air to the outside of the room.

[0013] (Gas pipe 13, compressor 14) The gas pipe 13 is a pipe that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12, and a gas-phase refrigerant flows inside the gas pipe 13. A compressor 14 is provided on the gas pipe 13. The compressor 14 is, for example, a scroll-type or rotary-type rotating machine, and compresses the gas-phase refrigerant that flows in from the inlet side, raises the pressure to a predetermined level, and then discharges the refrigerant into the gas pipe 13.

[0014] (Liquid pipe 15, expansion valve 16) The liquid pipe 15 is a pipe connecting the indoor heat exchanger 11 and the outdoor heat exchanger 12, and a liquid phase or a gas-liquid two-phase refrigerant flows inside. The liquid pipe 15 forms a circulation circuit together with the gas pipe 13. That is, both ends of the liquid pipe 15 are connected to ends of the indoor heat exchanger 11 and the outdoor heat exchanger 12 that are different from the ends to which the gas pipe 13 is connected. An expansion valve 16 is provided on the liquid pipe 15. The expansion valve 16 is, for example, an electromagnetic expansion valve, and has the function of expanding the refrigerant flowing through the liquid pipe 15 to reduce its pressure.

[0015] Although not shown in the figure, the four-way valve is a valve that switches the flow direction of the refrigerant in the gas pipe 13 and the liquid pipe 15 between cooling operation and heating operation. During cooling operation, as shown in Fig. 1, the refrigerant flows through the compressor 14, the outdoor heat exchanger 12, the expansion valve 16, and the indoor heat exchanger 11 in that order. On the other hand, during heating operation, as shown in Fig. 2, the refrigerant flows through the compressor 14, the indoor heat exchanger 11, the expansion valve 16, and the outdoor heat exchanger 12 in that order.

[0016] (Operation of refrigeration cycle circuit 10) Next, the operation of the refrigeration cycle circuit 10 during heating operation will be described. First, the high-temperature, high-pressure gas-phase refrigerant discharged from the compressor 14 flows into the indoor heat exchanger 11. In the indoor heat exchanger 11, the refrigerant exchanges heat with the indoor air, becoming a high-temperature, high-pressure liquid-phase refrigerant. The indoor air is heated by the heat exchange. This refrigerant is then reduced in pressure by passing through the expansion valve 16, becoming a low-temperature, low-pressure two-phase gas-liquid refrigerant. This refrigerant then flows into the outdoor heat exchanger and exchanges heat with the outdoor air. That is, the low-temperature refrigerant exchanges heat with the outdoor air, generating a low-temperature, low-pressure gas-phase refrigerant. This refrigerant flows into the compressor 14 again, and the above cycle occurs continuously.

[0017] On the other hand, during cooling operation, as shown in FIG. 5, the high-temperature, high-pressure gas-phase refrigerant discharged from the compressor 14 flows into the outdoor heat exchanger 12. In the outdoor heat exchanger 12, the refrigerant exchanges heat with the outdoor air, becoming a high-temperature, high-pressure liquid-phase refrigerant. This refrigerant then passes through the expansion valve 16, where it is reduced in pressure, becoming a low-temperature, low-pressure two-phase gas-liquid refrigerant. This refrigerant then flows into the indoor exchanger and exchanges heat with the indoor air. That is, the low-temperature refrigerant exchanges heat with the high-temperature air in the room, and the indoor air temperature drops. On the other hand, the temperature of the refrigerant rises, and it becomes a low-temperature, low-pressure gas-phase refrigerant. This refrigerant flows back into the compressor 14, and the above cycle occurs continuously.

[0018] (First control valve 20, second control valve 30) The first operating valve 20 is a valve that switches the flow state of the refrigerant in the gas pipe 13. The second operating valve 30 is a valve that switches the flow state of the refrigerant in the liquid pipe 15. As these valves, electromagnetic on-off valves are suitably used.

[0019] (Temperature measuring unit 41) The temperature measuring unit 41 is a temperature sensor that measures the outside air temperature. The temperature measuring unit 41 transmits the measured outside air temperature value as an electric signal to the control device 50, which will be described later.

[0020] (Leak detection sensor 42) The leak detection sensor 42 is provided near the indoor heat exchanger 11 and detects leakage of refrigerant into the room. The leak detection sensor 42 preferably uses a method of detecting leakage based on a chemical reaction between the refrigerant and a preheated metal oxide, for example. The leak detection sensor 42 is electrically connected to the control device 50, and when a refrigerant leak is detected, a signal to that effect is sent to the control device 50.

[0021] (Control device 50) 2, the control device 50 has a reception unit 51, a reading unit 52, a refrigerant amount acquisition unit 53, a comparison unit 54, a determination unit 55, a time acquisition unit 56, a valve drive unit 57, a sensor control unit 58, and a storage unit 59. The functions of these functional blocks will be described below with reference to the flowchart shown in FIG.

[0022] When a command to stop the operation of the air conditioner 1 is issued by the user, the reception unit 51 receives the command (step S1). When the reading unit 52 receives the command to stop the operation, the reading unit 52 reads (acquires) the outdoor air temperature, the charged refrigerant amount, and a predetermined refrigerant amount threshold value, which are the measurement results of the temperature measurement unit 41 (step S2). These values ​​are stored in advance in the storage unit 59. The refrigerant amount acquisition unit 53 acquires the indoor refrigerant amount for each elapsed time based on a table including the ratio of the predetermined time from the operation stop and the predicted value of the indoor refrigerant amount at the time elapsed (step S3). The table referred to here is a table in a format as shown in FIG. 3 as an example, and the relationship between the elapsed time and the predicted value of the indoor refrigerant amount is predetermined for each outdoor air temperature. The comparison unit 54 compares the predicted value of the indoor refrigerant amount at a specific elapsed time with the above-mentioned refrigerant amount threshold value (step S4). The determination unit 55 determines, based on the comparison result by the comparison unit 54, whether or not to perform a cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side.

[0023] More specifically, when the comparison unit 54 determines that the indoor refrigerant amount is less than the refrigerant amount threshold for at least a portion of each elapsed time on the table, the determination unit 55 determines that the cooling operation is not to be performed (step S5). After step S5, the time acquisition unit 56 acquires the shutoff time, which is the time until the shutoff valve is closed (step S6). In other words, the shutoff time refers to the time required for the refrigerant remaining on the indoor side to decrease over time and fall below the above-mentioned refrigerant amount threshold. After the shutoff time has elapsed, the valve drive unit 57 transmits an electric signal to the shutoff valve to close the shutoff valve (step S7).

[0024] On the other hand, if the comparison unit 54 determines in step S4 above that there is no elapsed time during which the indoor refrigerant amount is less than the refrigerant amount threshold, the determination unit 55 determines to start cooling operation (step S8). Thereafter, cooling operation is performed, and the refrigerant remaining on the indoor side is transferred to the outdoor side (step S9). This completes the process of stopping the air conditioner 1 after heating operation. After the shutoff valve is closed by the valve drive unit 57, the sensor control unit 58 stops the supply of electricity to the leak detection sensor 42.

[0025] (Action and effect) In air conditioners, the remaining amount of refrigerant in each device is specified by a standard. In particular, there is a demand to move the refrigerant to the outside of the room as much as possible, considering the risk of highly flammable refrigerant leaking into the room. As a technique for achieving this, a method has been adopted in the past in which the refrigerant circuits on the indoor side and the outdoor side are shut off after a cooling operation is performed for a certain period of time after the heating operation is stopped. However, the air in the room that has been warmed by the heating operation is cooled again by the above-mentioned cooling operation. This has led to a problem that the livability is impaired when the air conditioner is used. Therefore, the above-mentioned configurations are adopted in this embodiment.

[0026] According to the above configuration, when an operation stop command is issued during heating operation, the determination unit 55 determines whether or not to perform cooling operation to transfer the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side. As a result, if the amount of refrigerant remaining on the indoor heat exchanger 11 side is relatively small, the remaining amount of refrigerant meets the predetermined standard without performing cooling operation. Therefore, the possibility of performing unnecessary cooling operation is reduced, and it is possible to avoid a situation in which the air in the room warmed by the heating operation is cooled again by the cooling operation. Therefore, it is possible to perform stable operation that meets the standard related to the remaining amount of refrigerant without impairing the livability of the room after using the air conditioner 1. In particular, the necessity of cooling operation is determined by the indoor refrigerant amount for each elapsed time acquired by the refrigerant amount acquisition unit 53 based on a table including the ratio between the time from the predetermined operation stop and the predicted value of the indoor refrigerant amount at the time. Therefore, it is possible to stably and precisely determine the necessity of cooling operation without being affected by the indoor environment or the outdoor temperature. This makes it possible to further reduce the possibility of the indoor comfort being impaired.

[0027] According to the above configuration, when the comparison unit 54 determines that the indoor refrigerant amount is less than the refrigerant amount threshold for at least a part of the predetermined elapsed time, the determination unit 55 determines that the cooling operation is not performed. This can further reduce the possibility of performing an unnecessary cooling operation. In addition, when the cooling operation is not performed, the time acquisition unit 56 predicts the time until the indoor refrigerant amount falls below the refrigerant amount threshold from the table, and acquires the time until the shutoff valve is closed (shutoff time). After that, the valve drive unit 57 closes the shutoff valve after the shutoff time has elapsed. This allows the refrigerant to be transferred to the outdoor side by natural convection of the refrigerant without performing the cooling operation. Therefore, it is possible to minimize the risk that the indoor temperature drops after the heating operation, impairing habitability.

[0028] According to the above configuration, when the comparison unit 54 determines that there is no elapsed time during which the indoor refrigerant amount is less than the refrigerant amount threshold, it can be determined that the indoor refrigerant amount is excessive. For this reason, it is necessary to immediately reduce the indoor refrigerant amount by performing cooling operation. According to the above configuration, such a determination can be made immediately by the determination unit 55. Therefore, the period during which the indoor refrigerant amount is excessive is minimized, and it is possible to further improve the stability and reliability of the air conditioner 1.

[0029] According to the above configuration, the relationship between the elapsed time and the predicted value of the indoor refrigerant amount is predefined for each outdoor temperature in the table. Therefore, it is possible to precisely predict the change in the indoor refrigerant amount for each elapsed time, regardless of the change in the outdoor temperature. As a result, it is possible to provide a range of outdoor temperatures at which the air conditioner 1 can be operated, and the versatility of the air conditioner 1 can be further improved.

[0030] Here, the leak detection sensor 42 generally operates with the metal oxide preheated. Therefore, if preheating continues for a long period of time, the metal oxide may deteriorate and may not be able to maintain its function as a sensor. According to the above configuration, when the shutoff valve is closed and the condition is such that a refrigerant leak of an amount that may cause a fire cannot occur, the sensor control unit 58 stops the supply of electricity to the leak detection sensor. Therefore, the time that electricity is supplied to the leak detection sensor 42 can be minimized. As a result, it is possible to further reduce the possibility that the leak detection sensor 42 deteriorates or stops functioning, and the air conditioner 1 can operate more stably.

[0031] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.

[0032] For example, the configuration of the refrigeration cycle circuit 10 is merely an example, and in addition to the components described in the above embodiment, a receiver for storing a refrigerant, other heat exchangers, and the like can be added.

[0033] In addition, the range of outside air temperatures shown in the table is in increments of 5°C in the above embodiment, but as another example, it is also possible to use a table in increments of 1°C or 10°C. In either case, the same effects as those described above can be obtained.

[0034] Furthermore, the leakage detection sensor 42 does not necessarily have to be provided, and a configuration in which it is omitted is also possible.

[0035] It should be noted that the order of the processes performed by the control device 50 in the embodiment of the present disclosure may be changed as long as appropriate processes are performed.

[0036] The storage unit 59 and other storage devices in the embodiment of the present disclosure may be provided anywhere within the range where appropriate information is transmitted and received. Also, the storage unit 59 and other storage devices may be present in multiple locations within the range where appropriate information is transmitted and received, and data may be stored in a distributed manner.

[0037] The above-mentioned process steps of the control device 50 are stored in the form of a program in a recording medium readable by the computer 200, and the above-mentioned process is performed by the computer 200 reading and executing this program. A specific example of the computer 200 is shown below.

[0038] As shown in FIG. 6, the computer 200 includes a CPU 101, a main memory 102, a storage 103, and an interface 104. For example, the above-mentioned control device 50 is implemented in a computer 200. The operations of the above-mentioned processing units are stored in the storage 103 in the form of a program. The CPU 101 reads the program from the storage 103, loads it in the main memory 102, and executes the above-mentioned processing in accordance with the program. The CPU 101 also secures a storage area in the main memory 102 corresponding to the above-mentioned storage unit 59 in accordance with the program.

[0039] Examples of the storage 103 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), and a semiconductor memory. The storage 103 may be an internal medium directly connected to the bus of the computer 200, or an external medium connected to the computer 200 via the interface 104 or a communication line. In addition, when the program is distributed to the computer 200 via a communication line, the computer 200 that has received the program may expand the program in the main memory 102 and execute the above-mentioned process. The storage 103 is a non-transitory tangible storage medium.

[0040] The program may also realize some of the functions described above. Furthermore, the program may be a file that can realize the functions described above in combination with a program already recorded in computer 200, that is, a so-called difference file (difference program).

[0041] In addition to or instead of the above configuration, a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device), an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit), or a processing device similar thereto may be provided. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor may be realized by the integrated circuit.

[0042] <Additional Notes> The air conditioner described in each embodiment can be understood, for example, as follows.

[0043] (1) The air conditioner 1 according to the first aspect includes an indoor heat exchanger 11, an outdoor heat exchanger 12, a gas pipe 13 that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12 and through which a gas-phase refrigerant flows, a compressor 14 arranged on the gas pipe 13, a liquid pipe 15 that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12 and through which a liquid-phase or two-phase gas-liquid refrigerant flows and which forms a circulation circuit together with the gas pipe 13, an expansion valve 16 provided on the liquid pipe 15, a four-way valve that switches the flow direction of the refrigerant between a cooling operation and a heating operation, a shutoff valve provided on each of the gas pipe 13 and the liquid pipe 15, a temperature measurement unit 41 that measures an outdoor air temperature, and a control device 5. 0, and the control device 50 has a receiving unit 51 that receives an operation stop command, a reading unit 52 that reads the outside air temperature, the amount of enclosed refrigerant, and a predetermined refrigerant amount threshold when the operation stop command is received, a refrigerant amount acquisition unit 53 that acquires the indoor refrigerant amount for each elapsed time based on a table including a ratio between a predetermined time from the operation stop and a predicted value of the indoor refrigerant amount at the time the predetermined time has elapsed, a comparison unit 54 that compares the indoor refrigerant amount with the refrigerant amount threshold, and a determination unit 55 that determines whether to perform cooling operation to transfer the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side based on a comparison result by the comparison unit 54.

[0044] According to the above configuration, when an operation stop command is issued during heating operation, the judgment unit 55 judges whether or not to perform cooling operation to transfer the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side. As a result, if the amount of refrigerant remaining on the indoor heat exchanger 11 side is relatively small, the remaining amount of refrigerant satisfies a predetermined standard without performing cooling operation. Therefore, the possibility of performing unnecessary cooling operation is reduced, and it is possible to avoid a situation in which the indoor air warmed by heating operation is cooled again by cooling operation.

[0045] (2) The air conditioner 1 according to a second aspect is the air conditioner 1 of (1), wherein the judgment unit 55 judges that the indoor refrigerant amount is less than the refrigerant amount threshold for at least a portion of the elapsed time by the comparison unit 54, and the control device 50 further has a time acquisition unit 56 that acquires a shut-off time which is the time until the shut-off valve is closed, and a valve drive unit 57 that closes the shut-off valve when the shut-off time has elapsed.

[0046] According to the above configuration, when the comparison unit 54 determines that the indoor refrigerant amount is less than the refrigerant amount threshold for at least a part of the predetermined elapsed time, the determination unit 55 determines that the cooling operation is not to be performed. This can further reduce the possibility that the cooling operation is performed unnecessarily.

[0047] (3) The air conditioner 1 according to a third aspect is the air conditioner 1 of (1) or (2), and the judgment unit 55 judges to start the cooling operation when the comparison unit 54 judges that there is no elapsed time during which the indoor refrigerant amount is less than the refrigerant amount threshold value.

[0048] According to the above configuration, when the comparison unit 54 determines that there is no elapsed time during which the indoor refrigerant amount is less than the refrigerant amount threshold, it can be determined that the indoor refrigerant amount is excessive. Therefore, it is necessary to immediately reduce the indoor refrigerant amount by performing cooling operation. According to the above configuration, such a determination can be made immediately by the determination unit 55.

[0049] (4) An air conditioner 1 according to a fourth aspect is an air conditioner 1 according to any one of the aspects (1) to (3), wherein in the table, the relationship between the elapsed time and the predicted value of the indoor refrigerant amount is predetermined for each outside air temperature.

[0050] According to the above configuration, the relationship between the elapsed time and the predicted value of the indoor refrigerant amount is predefined for each outdoor temperature in the table, so that it is possible to precisely predict the change in the indoor refrigerant amount for each elapsed time, regardless of the change in the outdoor temperature.

[0051] (5) The air conditioning unit 1 according to a fifth aspect is the air conditioning unit 1 of (2), further comprising a leak detection sensor 42 that detects leakage of the refrigerant into the room, and a sensor control unit 58 provided in the control unit 50 that controls the supply of electricity to the leak detection sensor 42, and the sensor control unit 58 stops the supply of electricity to the leak detection sensor 42 after the shut-off valve is closed by the valve drive unit 57.

[0052] Here, the leak detection sensor 42 generally operates with the metal oxide preheated. Therefore, if preheating continues for a long period of time, the metal oxide may deteriorate and may not be able to maintain its function as a sensor. With the above configuration, when the shutoff valve is closed and conditions are set such that refrigerant leakage cannot occur, the sensor control unit 58 stops the supply of electricity to the leak detection sensor. Therefore, the time that electricity is supplied to the leak detection sensor 42 can be minimized. [Explanation of symbols]

[0053] 1...Air conditioner 10...Refrigeration cycle circuit 11...Indoor heat exchanger 12...Outdoor heat exchanger 13...Gas pipe 14...Compressor 15...Liquid pipe 16...Expansion valve 20...First operating valve 30...Second operating valve 41...Temperature measurement unit 42...Leak detection sensor 50...Control device 51...Reception unit 52...Reading unit 53...Refrigerant amount acquisition unit 54...Comparing unit 55...Determination unit 56...Time acquisition unit 57...Valve drive unit 58...Sensor control unit 59...Memory unit 101...CPU 102...Main memory 103...Storage 104...Interface 200...Computer

Claims

1. An indoor heat exchanger; An outdoor heat exchanger; a gas pipe connecting the indoor heat exchanger and the outdoor heat exchanger, through which a gas-phase refrigerant flows; a compressor disposed on the gas pipe; a liquid pipe that connects the indoor heat exchanger and the outdoor heat exchanger, through which a liquid-phase or two-phase gas-liquid refrigerant flows, and which forms a circulation circuit together with the gas pipe; an expansion valve provided on the liquid pipe; a four-way valve that switches the flow direction of the refrigerant between a cooling operation and a heating operation; a shutoff valve provided on each of the gas pipe and the liquid pipe; A temperature measuring unit that measures the outside air temperature; A control device; Equipped with The control device includes: A reception unit that receives an operation stop command; a reading unit that reads the outside air temperature, the amount of refrigerant enclosed, and a predetermined refrigerant amount threshold value when the operation stop command is received; a refrigerant amount acquisition unit that acquires an indoor refrigerant amount for each elapsed time based on a table including a ratio between a predetermined time from the operation stop and a predicted value of an indoor refrigerant amount at the time the predetermined time has elapsed; A comparison unit that compares the indoor refrigerant amount with the refrigerant amount threshold value; a determination unit that determines whether or not to perform a cooling operation for transferring the refrigerant remaining on the indoor heat exchanger side to the outdoor heat exchanger side based on a comparison result by the comparison unit; An air conditioning device having the above structure.

2. The determination unit determines not to perform the cooling operation when the comparison unit determines that the indoor refrigerant amount is less than the refrigerant amount threshold value for at least a portion of the elapsed time, The control device includes: a time acquisition unit that acquires a shutoff time, which is a time until the shutoff valve is closed; a valve driving unit that closes the shutoff valve when the shutoff time has elapsed; 2. The air conditioner of claim 1 further comprising:

3. The air conditioner according to claim 1 , wherein the determination unit determines to start the cooling operation when the comparison unit determines that there is no elapsed time during which the indoor refrigerant amount is less than the refrigerant amount threshold.

4. 3. The air conditioner according to claim 1, wherein in the table, a relationship between the elapsed time and the predicted value of the indoor refrigerant amount is determined in advance for each of the outside air temperatures.

5. a leakage detection sensor that detects leakage of the refrigerant into the room; A sensor control unit provided in the control device and controlling energization of the leakage detection sensor; Further equipped with The air conditioner according to claim 2 , wherein the sensor control unit stops the supply of electricity to the leakage detection sensor after the shutoff valve is closed by the valve driving unit.

Images