Air-conditioning device

Abstract

A control device for an air conditioning device comprises: a reception unit that receives an operation stop command; a reading unit that reads an outside air temperature, an enclosed refrigerant amount, and a predetermined refrigerant amount threshold when the operation stop command is received; a refrigerant amount acquisition unit that acquires an indoor-side refrigerant amount for each elapsed time on the basis of a table including a time from a predetermined operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses; a comparison unit that compares the indoor-side refrigerant amount with the refrigerant amount threshold; and a determination unit that determines whether to perform a cooling operation for transferring the refrigerant remaining on the indoor heat exchanger side to the outdoor heat exchanger side on the basis of a result of comparison performed by the comparison unit.

Description

Technical Field

[0001] The present disclosure relates to an air conditioner.

[0002] Priority is claimed on Japanese Patent Application No. 2023-181159, filed October 20, 2023, the content of which is incorporated herein by reference.Background Art

[0003] When the concentration of a flammable refrigerant leaked from the air conditioner is equal to or higher than the minimum combustion concentration, there is a risk of a fire. In consideration of the risk when a highly flammable refrigerant is leaked into the room, a method of shutting off the refrigerant circuits on the indoor side and the outdoor side during the operation stop of the air conditioner to reduce the amount of the refrigerant that may be leaked into the room is known. Therefore, as a specific technique for this, for example, as described in PTL 1, a method of performing a cooling operation for a certain time after stopping a heating operation and shutting off the refrigerant circuits on the indoor side and the outdoor side in a state where the refrigerant is moved to the outdoor side as much as possible has been adopted.Citation ListPatent Literature

[0004] [PTL 1] Japanese Patent No. 7159748Summary of InventionTechnical Problem

[0005] However, the air in the room heated by the heating operation is cooled again by the cooling operation. Therefore, there is a problem in that the habitability in a case of using the air conditioner is impaired.

[0006] The present disclosure has been made to solve the above-described problem, and an object thereof is to provide an air conditioner that can be stably operated even when a heating operation is stopped and that can ensure high habitability.Solution to Problem

[0007] In order to solve the above-described problem, an air conditioner according to the present disclosure includes an indoor heat exchanger, an outdoor heat exchanger, a gas pipe that connects the indoor heat exchanger and the outdoor heat exchanger and through which a gas-phase refrigerant flows, a compressor that is 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 gas-liquid two-phase refrigerant flows, and that forms a circulation circuit together with the gas pipe, an expansion valve that is provided on the liquid pipe, a four-way valve that switches a flow direction of the refrigerant between a cooling operation and a heating operation, shutoff valves that are respectively provided on the gas pipe and on the liquid pipe, a temperature measurement unit that measures an outside air temperature; and a control device, in which the control device includes a reception unit that receives an operation stop command, a reading unit that reads the outside air temperature, a charged refrigerant amount, and a predetermined refrigerant amount threshold value when the operation stop command is received, a refrigerant amount acquisition unit that acquires an indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from an operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses, a comparison unit that compares the indoor-side refrigerant amount with the refrigerant amount threshold value, and a determination unit that determines whether to perform a cooling operation for transferring the refrigerant remaining on an indoor heat exchanger side to an outdoor heat exchanger side, based on a comparison result by the comparison unit.Advantageous Effects of Invention

[0008] According to the present disclosure, it is possible to provide an air conditioner that can be stably operated even in a case of the heating operation stop and that can ensure high habitability.Brief Description of Drawings

[0009] FIG. 1 is a schematic diagram showing a refrigerant circuit of the air conditioner according to the embodiment of the present disclosure, and a diagram showing a state during a heating operation. FIG. 2 is a functional block diagram of a control device according to the embodiment of the present disclosure. FIG. 3 is an example of a table including a time from the operation stop of the air conditioner according to the embodiment of the present disclosure and a ratio of the predicted value of the indoor-side refrigerant amount when the time elapses. FIG. 4 is a flowchart showing a processing flow of a control device according to the embodiment of the present disclosure. FIG. 5 is a schematic diagram showing a refrigerant circuit of the air conditioner according to the embodiment of the present disclosure, and a diagram showing a state during a cooling operation. FIG. 6 is a hardware configuration diagram of a control device according to the embodiment of the present disclosure. Description of Embodiments(Configuration of Air Conditioner)

[0010] Hereinafter, an air conditioner 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. As shown in FIG. 1, the air conditioner 1 includes a refrigeration cycle circuit 10, a first operation valve 20, a second operation valve 30, a temperature measurement unit 41, a leakage-detecting sensor 42, and a control device 50. It should be noted that the first operation valve 20 and the second operation valve 30 may be collectively referred to as a "shutoff valve".(Refrigeration Cycle Circuit 10)

[0011] 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).

[0012] The indoor heat exchanger 11 performs heat exchange between air in a room and a refrigerant. The indoor heat exchanger 11 is, for example, a heat exchanger of a fin-and-tube type or a plate type, and a refrigerant flows inside. Although not shown, it is desirable that a fan that blows air into the room be provided in the indoor heat exchanger 11.

[0013] The outdoor heat exchanger 12 performs heat exchange between air outside the room and a refrigerant. The outdoor heat exchanger 12 is, for example, a heat exchanger of a fin-and-tube type or a plate type, and a refrigerant flows inside, as in the indoor heat exchanger 11. Although not shown, it is desirable that a fan that blows air into the outside of the room be provided in the outdoor heat exchanger 12.(Gas Pipe 13 and Compressor 14)

[0014] 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 compressor 14 is provided on the gas pipe 13. The compressor 14 is, for example, a scroll type or a rotary type rotary machine, and compresses a gas-phase refrigerant flowing in from an inlet side to raise the pressure of the refrigerant to a predetermined pressure, and then discharges the refrigerant to the gas pipe 13.(Liquid Pipe 15 and Expansion Valve 16)

[0015] The liquid pipe 15 is a pipe that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12, and a liquid-phase or gas-liquid two-phase refrigerant flows inside. The liquid pipe 15 forms a circulation circuit together with the gas pipe 13. That is, both end portions of the liquid pipe 15 are connected to end portions different from the end portions of the indoor heat exchanger 11 and the outdoor heat exchanger 12 to which the gas pipe 13 is connected. The expansion valve 16 is provided on the liquid pipe 15. The expansion valve 16 is, for example, an electromagnetic expansion valve, and has a function of expanding a refrigerant flowing through the liquid pipe 15 to reduce the pressure.

[0016] Although not shown, the four-way valve is a valve that switches a flow direction of the refrigerant in the gas pipe 13 and the liquid pipe 15 between the cooling operation and the heating operation. During the cooling operation, as shown in FIG. 1, the refrigerant flows in the order of the compressor 14, the outdoor heat exchanger 12, the expansion valve 16, and the indoor heat exchanger 11. On the other hand, during the heating operation, as shown in FIG. 2, the refrigerant flows in the order of the compressor 14, the indoor heat exchanger 11, the expansion valve 16, and the outdoor heat exchanger 12.(Operation of Refrigeration Cycle Circuit 10)

[0017] Subsequently, the operation of the refrigeration cycle circuit 10 during the heating operation will be described. First, the high-temperature and 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 air in the room to become a high-temperature and high-pressure liquid-phase refrigerant. The air in the room is heated by the heat exchange. Next, the refrigerant passes through the expansion valve 16 to be depressurized, and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. Further, the refrigerant flows into the outdoor heat exchanger and exchanges heat with the air outside the room. That is, the low-temperature refrigerant exchanges heat with the air outside the room, and a low-temperature and low-pressure gas-phase refrigerant is generated. The refrigerant flows again into the compressor 14, and the above-described cycle continuously occurs.

[0018] On the other hand, during the cooling operation, as shown in FIG. 5, the high-temperature and 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 air outside the room to become a high-temperature and high-pressure liquid-phase refrigerant. Next, the refrigerant passes through the expansion valve 16 to be depressurized, and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. Further, the refrigerant flows into the indoor heat exchanger and exchanges heat with the air in the room. That is, the low-temperature refrigerant exchanges heat with the high-temperature air in the room, and the air temperature in the room is lowered. On the other hand, the temperature of the refrigerant is raised, and the refrigerant becomes a low-temperature and low-pressure gas-phase refrigerant. The refrigerant flows again into the compressor 14, and the above-described cycle continuously occurs.(First Operation Valve 20 and Second Operation Valve 30)

[0019] The first operation valve 20 is a valve that switches a flow state of the refrigerant in the gas pipe 13. The second operation valve 30 is a valve that switches a flow state of the refrigerant in the liquid pipe 15. As these valves, an electromagnetic on / off valve is suitably used.(Temperature Measurement Unit 41)

[0020] The temperature measurement unit 41 is a temperature sensor that measures the outside air temperature. The temperature measurement unit 41 transmits the measured value of the outside air temperature as an electric signal to the control device 50 described below.(Leakage-Detecting Sensor 42)

[0021] The leakage-detecting sensor 42 is a sensor that is provided near the indoor heat exchanger 11 and that detects the leakage of the refrigerant into the room. As the leakage-detecting sensor 42, for example, a method of detecting the leakage based on a chemical reaction with the refrigerant in a state where a metal oxide is preheated is suitably used. The leakage-detecting sensor 42 is electrically connected to the control device 50, and when the leakage of the refrigerant is detected, a signal indicating the fact is transmitted to the control device 50.(Control Device 50)

[0022] As shown in FIG. 2, the control device 50 includes 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. Hereinafter, the functions of these functional blocks will be described with reference to a flowchart shown in FIG. 4.

[0023] When the operation stop command of the air conditioner 1 is issued by the user, the reception unit 51 receives the command (step S1). When the operation stop command is received, the reading unit 52 reads (acquires) the outside air temperature, which is the measurement result of the temperature measurement unit 41, the charged refrigerant amount, and the predetermined refrigerant amount threshold value (step S2). These numerical values are stored in advance in the storage unit 59. The refrigerant amount acquisition unit 53 acquires the indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from the operation stop and a ratio of the predicted value of the indoor-side refrigerant amount when the time elapses (step S3). The table referred to here is, for example, a table in a form shown in FIG. 3, in which a relationship between the elapsed time and the predicted value of the indoor-side refrigerant amount is predetermined for each outside air temperature. The comparison unit 54 compares the predicted value of the indoor-side refrigerant amount at the specific elapsed time with the refrigerant amount threshold value (step S4). The determination unit 55 determines whether to perform the cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side, based on the comparison result by the comparison unit 54.

[0024] More specifically, when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the elapsed times on the table, the determination unit 55 determines not to perform the cooling operation (step S5). After step S5, the time acquisition unit 56 acquires a shutoff time, which is a time until the shutoff valve is closed (step S6). That is, the shutoff time refers to a time required until the refrigerant remaining on the indoor side is reduced to be lower than the above-described refrigerant amount threshold value as the time elapses. After the shutoff time elapses, the valve drive unit 57 transmits an electric signal for closing the shutoff valve to the shutoff valve (step S7).

[0025] On the other hand, when the comparison unit 54 determines in step S4 that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value, the determination unit 55 determines to start the cooling operation (step S8). Thereafter, the cooling operation is performed to transfer the refrigerant remaining on the indoor side to the outdoor side (step S9). As described above, the stop process of the air conditioner 1 after the heating operation is completed. It should be noted that the sensor control unit 58 stops the energization to the leakage-detecting sensor 42 after the shutoff valve is closed by the valve drive unit 57.(Operations and Effects)

[0026] In the air conditioner, the amount of the refrigerant remaining in each device is defined by a standard. In particular, in consideration of the risk when a highly flammable refrigerant is leaked into the room, there is a request to move the refrigerant to the outdoor side as much as possible. Therefore, as a technique for this, in the related art, a method of performing the cooling operation for a certain time after stopping the heating operation and then shutting off the refrigerant circuits on the indoor side and the outdoor side has been adopted. However, the air in the room heated by the heating operation is cooled again by the cooling operation. Therefore, there is a problem in that the habitability in a case of using the air conditioner is impaired. Therefore, in the present embodiment, each of the configurations described above is adopted.

[0027] According to the above-described configuration, when the operation stop command is issued during the heating operation, the determination unit 55 determines whether to perform the cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side. As a result, when the amount of the refrigerant remaining on the indoor heat exchanger 11 side is relatively small, the state in which the amount of the remaining refrigerant satisfies the predetermined standard is achieved without performing the cooling operation. Therefore, the possibility that the unnecessary cooling operation is performed is reduced, and it is possible to avoid a situation in which the air in the room heated by the heating operation is cooled again by the cooling operation. Therefore, it is possible to perform a stable operation that satisfies the standard related to the amount of the remaining refrigerant without impairing the habitability of the room after using the air conditioner 1. In particular, the necessity of the cooling operation is determined by the indoor-side refrigerant amount for each elapsed time acquired by the refrigerant amount acquisition unit 53 based on a table including a predetermined time from the operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses. Therefore, it is possible to stably and accurately determine the necessity of the cooling operation regardless of the indoor environment or the outside air temperature. Therefore, it is possible to further reduce the possibility that the comfort in the room is impaired.

[0028] According to the above-described configuration, when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the predetermined elapsed times, the determination unit 55 determines not to perform the cooling operation. Accordingly, the possibility that the unnecessary cooling operation is performed can be further reduced. In addition, when the cooling operation is not performed, the time acquisition unit 56 predicts the time until the indoor-side refrigerant amount is lower than the refrigerant amount threshold value from the table, and acquires the time (shutoff time) until the shutoff valve is closed. Thereafter, after the shutoff time elapses, the valve drive unit 57 closes the shutoff valve. As a result, the refrigerant can 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 habitability is impaired due to a decrease in the indoor temperature after the heating operation.

[0029] According to the above-described configuration, when the comparison unit 54 determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value, it is possible to determine that the indoor-side refrigerant amount is excessive. Therefore, it is necessary to immediately reduce the indoor-side refrigerant amount by performing the cooling operation. According to the above-described configuration, such a determination can be immediately made by the determination unit 55. Therefore, the period in which the indoor-side refrigerant amount is excessive is minimized, and the stability and reliability of the air conditioner 1 can be further improved.

[0030] According to the above-described configuration, the relationship between the elapsed time and a predicted value of the indoor-side refrigerant amount is predetermined for each outside air temperature in the table. Therefore, it is possible to accurately predict the change in the indoor-side refrigerant amount for each elapsed time regardless of the change in the outside air temperature. As a result, the range of the outside air temperature at which the air conditioner 1 can be operated can be widened, and the versatility of the air conditioner 1 can be further improved.

[0031] Here, the leakage-detecting sensor 42 generally operates in a state where a metal oxide is preheated. Therefore, when the preheating is continued for a long period of time, a metal oxide may deteriorate, and the function as the sensor may not be maintained. According to the above-described configuration, when the shutoff valve is closed and the condition in which the leakage of the refrigerant in an amount that may cause a fire cannot occur is established, the sensor control unit 58 stops the energization to the leakage-detecting sensor. Therefore, the energization time to the leakage-detecting sensor 42 can be minimized. As a result, it is possible to further reduce the possibility that the deterioration or the function stop of the leakage-detecting sensor 42 occurs, and it is possible to realize a more stable operation as the air conditioner 1.(Other Embodiments)

[0032] The embodiments of the present disclosure have been described in detail with reference to the drawings hereinbefore. However, the specific configuration is not limited to the embodiments, and includes design changes and the like within a scope not departing from the gist of the present disclosure.

[0033] For example, the configuration of the refrigeration cycle circuit 10 is an example, and a receiver that stores the refrigerant, other heat exchangers, and the like can be added in addition to the components described in the embodiment.

[0034] In addition, the width of the outside air temperature shown in the table is 5°C in the embodiment, but as another example, a table of 1°C or 10°C can also be used. In either case, the same operation and effect as those described above can be obtained.

[0035] Furthermore, the leakage-detecting sensor 42 does not necessarily need to be provided, and a configuration in which the leakage-detecting sensor 42 is omitted can also be adopted.

[0036] In a processing flow of the control device 50 of the embodiments of the present disclosure, the order of processing may be changed in a range in which appropriate processing is performed.

[0037] Each of the storage unit 59 and other storage devices in the embodiments of the present disclosure may be provided anywhere in a range in which appropriate information is transmitted and received. Further, each of the storage unit 59 and the other storage devices may be present in a plurality in a range in which appropriate information is transmitted and received, and data may be stored in a distributed manner.

[0038] The process of the processing by the control device 50 described above is stored in the form of a program in a recording medium that can be read by a computer 200, and the computer 200 reads out and executes this program, so that the processing is performed. A specific example of the computer 200 will be described below.

[0039] As shown in FIG. 6, the computer 200 includes a CPU 101, a main memory 102, a storage 103, and an interface 104.

[0040] For example, the control device 50 is mounted on the computer 200. Further, the operation of each processing unit described above is stored in the storage 103 in the form of a program. The CPU 101 reads out the program from the storage 103, loads the program into the main memory 102, and performs the above-described processing according to the program. Further, the CPU 101 secures a storage area corresponding to the storage unit 59 described above in the main memory 102 according to the program.

[0041] 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 a bus of the computer 200 or may be an external medium connected to the computer 200 via the interface 104 or a communication line. Further, when this program is delivered to the computer 200 through the communication line, the computer 200 to which the program is delivered may load the program into the main memory 102 and may perform the processing. The storage 103 is a non-transitory tangible storage medium.

[0042] Further, the above program may implement some of the above-mentioned functions. Furthermore, the program may be a so-called differential file (differential program) that can realize the above functions in combination with a program already recorded in the computer 200.

[0043] A custom large scale integrated circuit (LSI) such as a programmable logic device (PLD), an application specific integrated circuit (ASIC), a graphics processing unit (GPU), and a processing device similar thereto may be provided in addition to the above-described configuration or instead of the above-described configuration. As examples of the PLD, a programmable array logic (PAL), a generic array logic (GAL), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA) can be given. In this case, a part or all of the functions realized by the processor may be realized by the integrated circuit.<Additional Notes>

[0044] The air conditioning device described in each embodiment is understood as follows, for example.

[0045] (1) An air conditioner 1 according to a 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 that is disposed on the gas pipe 13, a liquid pipe 15 that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12, through which a liquid-phase or gas-liquid two-phase refrigerant flows, and that forms a circulation circuit together with the gas pipe 13, an expansion valve 16 that is provided on the liquid pipe 15, a four-way valve that switches a flow direction of the refrigerant between a cooling operation and a heating operation, shutoff valves that are respectively provided on the gas pipe 13 and on the liquid pipe 15, a temperature measurement unit 41 that measures an outside air temperature, and a control device 50, in which the control device 50 includes a reception unit 51 that receives an operation stop command, a reading unit 52 that reads the outside air temperature, a charged refrigerant amount, and a predetermined refrigerant amount threshold value when the operation stop command is received, a refrigerant amount acquisition unit 53 that acquires an indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from an operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses, a comparison unit 54 that compares the indoor-side refrigerant amount with the refrigerant amount threshold value, and a determination unit 55 that determines whether to perform a cooling operation for transferring the refrigerant remaining on an indoor heat exchanger 11 side to an outdoor heat exchanger 12 side, based on a comparison result by the comparison unit 54.

[0046] According to the above-described configuration, when the operation stop command is issued during the heating operation, the determination unit 55 determines whether to perform the cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side. As a result, when the amount of the refrigerant remaining on the indoor heat exchanger 11 side is relatively small, the state in which the amount of the remaining refrigerant satisfies the predetermined standard is achieved without performing the cooling operation. Therefore, the possibility that the unnecessary cooling operation is performed is reduced, and it is possible to avoid a situation in which the air in the room heated by the heating operation is cooled again by the cooling operation.

[0047] (2) An air conditioner 1 according to a second aspect is the air conditioner 1 of (1), in which the determination unit 55 determines not to perform the cooling operation when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the elapsed time, and the control device 50 further includes a time acquisition unit 56 that acquires a shutoff time, which is a time until the shutoff valves are closed, and a valve drive unit 57 that closes the shutoff valves when the shutoff time elapses.

[0048] According to the above-described configuration, when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the predetermined elapsed times, the determination unit 55 determines not to perform the cooling operation. Accordingly, the possibility that the unnecessary cooling operation is performed can be further reduced.

[0049] (3) An air conditioner 1 according to a third aspect is the air conditioner 1 of (1) or (2), in which the determination unit 55 determines to start the cooling operation when the comparison unit 54 determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value.

[0050] According to the above-described configuration, when the comparison unit 54 determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value, it is possible to determine that the indoor-side refrigerant amount is excessive. Therefore, it is necessary to immediately reduce the indoor-side refrigerant amount by performing the cooling operation. According to the above-described configuration, such a determination can be immediately made by the determination unit 55.

[0051] (4) An air conditioner 1 according to a fourth aspect is the air conditioner 1 according to any one aspect of (1) to (3), in which in the table, a relationship between the elapsed time and the predicted value of the indoor-side refrigerant amount is predetermined for each of the outside air temperatures.

[0052] According to the above-described configuration, the relationship between the elapsed time and a predicted value of the indoor-side refrigerant amount is predetermined for each outside air temperature in the table. Therefore, it is possible to accurately predict the change in the indoor-side refrigerant amount for each elapsed time regardless of the change in the outside air temperature.

[0053] (5) An air conditioner 1 according to a fifth aspect is the air conditioner 1 of (2), further including: a leakage-detecting sensor 42 that detects leakage of the refrigerant into a room; and a sensor control unit 58 that is provided in the control device 50 and controls energization to the leakage-detecting sensor 42, in which the sensor control unit 58 stops the energization to the leakage-detecting sensor 42 after the shutoff valves are closed by the valve drive unit 57.

[0054] Here, the leakage-detecting sensor 42 generally operates in a state where a metal oxide is preheated. Therefore, when the preheating is continued for a long period of time, a metal oxide may deteriorate, and the function as the sensor may not be maintained. According to the above-described configuration, when the shutoff valve is closed and the condition in which the leakage of the refrigerant cannot occur is established, the sensor control unit 58 stops the energization to the leakage-detecting sensor. Therefore, the energization time to the leakage-detecting sensor 42 can be minimized.Industrial Applicability

[0055] According to the present disclosure, it is possible to provide an air conditioner that can be stably operated even in a case of the heating operation stop and that can ensure high habitability.Reference Signs List

[0056] 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 operation valve 30: second operation valve 41: temperature measurement unit 42: leakage-detecting sensor 50: control device 51: reception unit 52: reading unit 53: refrigerant amount acquisition unit 54: comparison unit 55: determination unit 56: time acquisition unit 57: valve drive unit 58: sensor control unit 59: storage unit 101: CPU 102: main memory 103: storage 104: interface 200: computer

Examples

Embodiment Construction

(Configuration of Air Conditioner)

[0010]Hereinafter, an air conditioner 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. As shown in FIG. 1, the air conditioner 1 includes a refrigeration cycle circuit 10, a first operation valve 20, a second operation valve 30, a temperature measurement unit 41, a leakage-detecting sensor 42, and a control device 50. It should be noted that the first operation valve 20 and the second operation valve 30 may be collectively referred to as a "shutoff valve".

(Refrigeration Cycle Circuit 10)

[0011]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).

[0012]The indoor heat exchanger 11 performs heat exchange between air in a room and a refrigerant. The indoor heat exchanger 11 is, for example, a heat exchanger of a fin-and-tube type or a plate type...

Technical Field

[0001] The present disclosure relates to an air conditioner.

[0002] Priority is claimed on Japanese Patent Application No. 2023-181159, filed October 20, 2023, the content of which is incorporated herein by reference.Background Art

[0003] When the concentration of a flammable refrigerant leaked from the air conditioner is equal to or higher than the minimum combustion concentration, there is a risk of a fire. In consideration of the risk when a highly flammable refrigerant is leaked into the room, a method of shutting off the refrigerant circuits on the indoor side and the outdoor side during the operation stop of the air conditioner to reduce the amount of the refrigerant that may be leaked into the room is known. Therefore, as a specific technique for this, for example, as described in PTL 1, a method of performing a cooling operation for a certain time after stopping a heating operation and shutting off the refrigerant circuits on the indoor side and the outdoor side in a state where the refrigerant is moved to the outdoor side as much as possible has been adopted.Citation ListPatent Literature

[0004] [PTL 1] Japanese Patent No. 7159748Summary of InventionTechnical Problem

[0005] However, the air in the room heated by the heating operation is cooled again by the cooling operation. Therefore, there is a problem in that the habitability in a case of using the air conditioner is impaired.

[0006] The present disclosure has been made to solve the above-described problem, and an object thereof is to provide an air conditioner that can be stably operated even when a heating operation is stopped and that can ensure high habitability.Solution to Problem

[0007] In order to solve the above-described problem, an air conditioner according to the present disclosure includes an indoor heat exchanger, an outdoor heat exchanger, a gas pipe that connects the indoor heat exchanger and the outdoor heat exchanger and through which a gas-phase refrigerant flows, a compressor that is 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 gas-liquid two-phase refrigerant flows, and that forms a circulation circuit together with the gas pipe, an expansion valve that is provided on the liquid pipe, a four-way valve that switches a flow direction of the refrigerant between a cooling operation and a heating operation, shutoff valves that are respectively provided on the gas pipe and on the liquid pipe, a temperature measurement unit that measures an outside air temperature; and a control device, in which the control device includes a reception unit that receives an operation stop command, a reading unit that reads the outside air temperature, a charged refrigerant amount, and a predetermined refrigerant amount threshold value when the operation stop command is received, a refrigerant amount acquisition unit that acquires an indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from an operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses, a comparison unit that compares the indoor-side refrigerant amount with the refrigerant amount threshold value, and a determination unit that determines whether to perform a cooling operation for transferring the refrigerant remaining on an indoor heat exchanger side to an outdoor heat exchanger side, based on a comparison result by the comparison unit.Advantageous Effects of Invention

[0008] According to the present disclosure, it is possible to provide an air conditioner that can be stably operated even in a case of the heating operation stop and that can ensure high habitability.Brief Description of Drawings

[0009] FIG. 1 is a schematic diagram showing a refrigerant circuit of the air conditioner according to the embodiment of the present disclosure, and a diagram showing a state during a heating operation. FIG. 2 is a functional block diagram of a control device according to the embodiment of the present disclosure. FIG. 3 is an example of a table including a time from the operation stop of the air conditioner according to the embodiment of the present disclosure and a ratio of the predicted value of the indoor-side refrigerant amount when the time elapses. FIG. 4 is a flowchart showing a processing flow of a control device according to the embodiment of the present disclosure. FIG. 5 is a schematic diagram showing a refrigerant circuit of the air conditioner according to the embodiment of the present disclosure, and a diagram showing a state during a cooling operation. FIG. 6 is a hardware configuration diagram of a control device according to the embodiment of the present disclosure. Description of Embodiments(Configuration of Air Conditioner)

[0010] Hereinafter, an air conditioner 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. As shown in FIG. 1, the air conditioner 1 includes a refrigeration cycle circuit 10, a first operation valve 20, a second operation valve 30, a temperature measurement unit 41, a leakage-detecting sensor 42, and a control device 50. It should be noted that the first operation valve 20 and the second operation valve 30 may be collectively referred to as a "shutoff valve".(Refrigeration Cycle Circuit 10)

[0011] 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).

[0012] The indoor heat exchanger 11 performs heat exchange between air in a room and a refrigerant. The indoor heat exchanger 11 is, for example, a heat exchanger of a fin-and-tube type or a plate type, and a refrigerant flows inside. Although not shown, it is desirable that a fan that blows air into the room be provided in the indoor heat exchanger 11.

[0013] The outdoor heat exchanger 12 performs heat exchange between air outside the room and a refrigerant. The outdoor heat exchanger 12 is, for example, a heat exchanger of a fin-and-tube type or a plate type, and a refrigerant flows inside, as in the indoor heat exchanger 11. Although not shown, it is desirable that a fan that blows air into the outside of the room be provided in the outdoor heat exchanger 12.(Gas Pipe 13 and Compressor 14)

[0014] 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 compressor 14 is provided on the gas pipe 13. The compressor 14 is, for example, a scroll type or a rotary type rotary machine, and compresses a gas-phase refrigerant flowing in from an inlet side to raise the pressure of the refrigerant to a predetermined pressure, and then discharges the refrigerant to the gas pipe 13.(Liquid Pipe 15 and Expansion Valve 16)

[0015] The liquid pipe 15 is a pipe that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12, and a liquid-phase or gas-liquid two-phase refrigerant flows inside. The liquid pipe 15 forms a circulation circuit together with the gas pipe 13. That is, both end portions of the liquid pipe 15 are connected to end portions different from the end portions of the indoor heat exchanger 11 and the outdoor heat exchanger 12 to which the gas pipe 13 is connected. The expansion valve 16 is provided on the liquid pipe 15. The expansion valve 16 is, for example, an electromagnetic expansion valve, and has a function of expanding a refrigerant flowing through the liquid pipe 15 to reduce the pressure.

[0016] Although not shown, the four-way valve is a valve that switches a flow direction of the refrigerant in the gas pipe 13 and the liquid pipe 15 between the cooling operation and the heating operation. During the cooling operation, as shown in FIG. 1, the refrigerant flows in the order of the compressor 14, the outdoor heat exchanger 12, the expansion valve 16, and the indoor heat exchanger 11. On the other hand, during the heating operation, as shown in FIG. 2, the refrigerant flows in the order of the compressor 14, the indoor heat exchanger 11, the expansion valve 16, and the outdoor heat exchanger 12.(Operation of Refrigeration Cycle Circuit 10)

[0017] Subsequently, the operation of the refrigeration cycle circuit 10 during the heating operation will be described. First, the high-temperature and 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 air in the room to become a high-temperature and high-pressure liquid-phase refrigerant. The air in the room is heated by the heat exchange. Next, the refrigerant passes through the expansion valve 16 to be depressurized, and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. Further, the refrigerant flows into the outdoor heat exchanger and exchanges heat with the air outside the room. That is, the low-temperature refrigerant exchanges heat with the air outside the room, and a low-temperature and low-pressure gas-phase refrigerant is generated. The refrigerant flows again into the compressor 14, and the above-described cycle continuously occurs.

[0018] On the other hand, during the cooling operation, as shown in FIG. 5, the high-temperature and 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 air outside the room to become a high-temperature and high-pressure liquid-phase refrigerant. Next, the refrigerant passes through the expansion valve 16 to be depressurized, and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. Further, the refrigerant flows into the indoor heat exchanger and exchanges heat with the air in the room. That is, the low-temperature refrigerant exchanges heat with the high-temperature air in the room, and the air temperature in the room is lowered. On the other hand, the temperature of the refrigerant is raised, and the refrigerant becomes a low-temperature and low-pressure gas-phase refrigerant. The refrigerant flows again into the compressor 14, and the above-described cycle continuously occurs.(First Operation Valve 20 and Second Operation Valve 30)

[0019] The first operation valve 20 is a valve that switches a flow state of the refrigerant in the gas pipe 13. The second operation valve 30 is a valve that switches a flow state of the refrigerant in the liquid pipe 15. As these valves, an electromagnetic on / off valve is suitably used.(Temperature Measurement Unit 41)

[0020] The temperature measurement unit 41 is a temperature sensor that measures the outside air temperature. The temperature measurement unit 41 transmits the measured value of the outside air temperature as an electric signal to the control device 50 described below.(Leakage-Detecting Sensor 42)

[0021] The leakage-detecting sensor 42 is a sensor that is provided near the indoor heat exchanger 11 and that detects the leakage of the refrigerant into the room. As the leakage-detecting sensor 42, for example, a method of detecting the leakage based on a chemical reaction with the refrigerant in a state where a metal oxide is preheated is suitably used. The leakage-detecting sensor 42 is electrically connected to the control device 50, and when the leakage of the refrigerant is detected, a signal indicating the fact is transmitted to the control device 50.(Control Device 50)

[0022] As shown in FIG. 2, the control device 50 includes 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. Hereinafter, the functions of these functional blocks will be described with reference to a flowchart shown in FIG. 4.

[0023] When the operation stop command of the air conditioner 1 is issued by the user, the reception unit 51 receives the command (step S1). When the operation stop command is received, the reading unit 52 reads (acquires) the outside air temperature, which is the measurement result of the temperature measurement unit 41, the charged refrigerant amount, and the predetermined refrigerant amount threshold value (step S2). These numerical values are stored in advance in the storage unit 59. The refrigerant amount acquisition unit 53 acquires the indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from the operation stop and a ratio of the predicted value of the indoor-side refrigerant amount when the time elapses (step S3). The table referred to here is, for example, a table in a form shown in FIG. 3, in which a relationship between the elapsed time and the predicted value of the indoor-side refrigerant amount is predetermined for each outside air temperature. The comparison unit 54 compares the predicted value of the indoor-side refrigerant amount at the specific elapsed time with the refrigerant amount threshold value (step S4). The determination unit 55 determines whether to perform the cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side, based on the comparison result by the comparison unit 54.

[0024] More specifically, when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the elapsed times on the table, the determination unit 55 determines not to perform the cooling operation (step S5). After step S5, the time acquisition unit 56 acquires a shutoff time, which is a time until the shutoff valve is closed (step S6). That is, the shutoff time refers to a time required until the refrigerant remaining on the indoor side is reduced to be lower than the above-described refrigerant amount threshold value as the time elapses. After the shutoff time elapses, the valve drive unit 57 transmits an electric signal for closing the shutoff valve to the shutoff valve (step S7).

[0025] On the other hand, when the comparison unit 54 determines in step S4 that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value, the determination unit 55 determines to start the cooling operation (step S8). Thereafter, the cooling operation is performed to transfer the refrigerant remaining on the indoor side to the outdoor side (step S9). As described above, the stop process of the air conditioner 1 after the heating operation is completed. It should be noted that the sensor control unit 58 stops the energization to the leakage-detecting sensor 42 after the shutoff valve is closed by the valve drive unit 57.(Operations and Effects)

[0026] In the air conditioner, the amount of the refrigerant remaining in each device is defined by a standard. In particular, in consideration of the risk when a highly flammable refrigerant is leaked into the room, there is a request to move the refrigerant to the outdoor side as much as possible. Therefore, as a technique for this, in the related art, a method of performing the cooling operation for a certain time after stopping the heating operation and then shutting off the refrigerant circuits on the indoor side and the outdoor side has been adopted. However, the air in the room heated by the heating operation is cooled again by the cooling operation. Therefore, there is a problem in that the habitability in a case of using the air conditioner is impaired. Therefore, in the present embodiment, each of the configurations described above is adopted.

[0027] According to the above-described configuration, when the operation stop command is issued during the heating operation, the determination unit 55 determines whether to perform the cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side. As a result, when the amount of the refrigerant remaining on the indoor heat exchanger 11 side is relatively small, the state in which the amount of the remaining refrigerant satisfies the predetermined standard is achieved without performing the cooling operation. Therefore, the possibility that the unnecessary cooling operation is performed is reduced, and it is possible to avoid a situation in which the air in the room heated by the heating operation is cooled again by the cooling operation. Therefore, it is possible to perform a stable operation that satisfies the standard related to the amount of the remaining refrigerant without impairing the habitability of the room after using the air conditioner 1. In particular, the necessity of the cooling operation is determined by the indoor-side refrigerant amount for each elapsed time acquired by the refrigerant amount acquisition unit 53 based on a table including a predetermined time from the operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses. Therefore, it is possible to stably and accurately determine the necessity of the cooling operation regardless of the indoor environment or the outside air temperature. Therefore, it is possible to further reduce the possibility that the comfort in the room is impaired.

[0028] According to the above-described configuration, when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the predetermined elapsed times, the determination unit 55 determines not to perform the cooling operation. Accordingly, the possibility that the unnecessary cooling operation is performed can be further reduced. In addition, when the cooling operation is not performed, the time acquisition unit 56 predicts the time until the indoor-side refrigerant amount is lower than the refrigerant amount threshold value from the table, and acquires the time (shutoff time) until the shutoff valve is closed. Thereafter, after the shutoff time elapses, the valve drive unit 57 closes the shutoff valve. As a result, the refrigerant can 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 habitability is impaired due to a decrease in the indoor temperature after the heating operation.

[0029] According to the above-described configuration, when the comparison unit 54 determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value, it is possible to determine that the indoor-side refrigerant amount is excessive. Therefore, it is necessary to immediately reduce the indoor-side refrigerant amount by performing the cooling operation. According to the above-described configuration, such a determination can be immediately made by the determination unit 55. Therefore, the period in which the indoor-side refrigerant amount is excessive is minimized, and the stability and reliability of the air conditioner 1 can be further improved.

[0030] According to the above-described configuration, the relationship between the elapsed time and a predicted value of the indoor-side refrigerant amount is predetermined for each outside air temperature in the table. Therefore, it is possible to accurately predict the change in the indoor-side refrigerant amount for each elapsed time regardless of the change in the outside air temperature. As a result, the range of the outside air temperature at which the air conditioner 1 can be operated can be widened, and the versatility of the air conditioner 1 can be further improved.

[0031] Here, the leakage-detecting sensor 42 generally operates in a state where a metal oxide is preheated. Therefore, when the preheating is continued for a long period of time, a metal oxide may deteriorate, and the function as the sensor may not be maintained. According to the above-described configuration, when the shutoff valve is closed and the condition in which the leakage of the refrigerant in an amount that may cause a fire cannot occur is established, the sensor control unit 58 stops the energization to the leakage-detecting sensor. Therefore, the energization time to the leakage-detecting sensor 42 can be minimized. As a result, it is possible to further reduce the possibility that the deterioration or the function stop of the leakage-detecting sensor 42 occurs, and it is possible to realize a more stable operation as the air conditioner 1.(Other Embodiments)

[0032] The embodiments of the present disclosure have been described in detail with reference to the drawings hereinbefore. However, the specific configuration is not limited to the embodiments, and includes design changes and the like within a scope not departing from the gist of the present disclosure.

[0033] For example, the configuration of the refrigeration cycle circuit 10 is an example, and a receiver that stores the refrigerant, other heat exchangers, and the like can be added in addition to the components described in the embodiment.

[0034] In addition, the width of the outside air temperature shown in the table is 5°C in the embodiment, but as another example, a table of 1°C or 10°C can also be used. In either case, the same operation and effect as those described above can be obtained.

[0035] Furthermore, the leakage-detecting sensor 42 does not necessarily need to be provided, and a configuration in which the leakage-detecting sensor 42 is omitted can also be adopted.

[0036] In a processing flow of the control device 50 of the embodiments of the present disclosure, the order of processing may be changed in a range in which appropriate processing is performed.

[0037] Each of the storage unit 59 and other storage devices in the embodiments of the present disclosure may be provided anywhere in a range in which appropriate information is transmitted and received. Further, each of the storage unit 59 and the other storage devices may be present in a plurality in a range in which appropriate information is transmitted and received, and data may be stored in a distributed manner.

[0038] The process of the processing by the control device 50 described above is stored in the form of a program in a recording medium that can be read by a computer 200, and the computer 200 reads out and executes this program, so that the processing is performed. A specific example of the computer 200 will be described below.

[0039] As shown in FIG. 6, the computer 200 includes a CPU 101, a main memory 102, a storage 103, and an interface 104.

[0040] For example, the control device 50 is mounted on the computer 200. Further, the operation of each processing unit described above is stored in the storage 103 in the form of a program. The CPU 101 reads out the program from the storage 103, loads the program into the main memory 102, and performs the above-described processing according to the program. Further, the CPU 101 secures a storage area corresponding to the storage unit 59 described above in the main memory 102 according to the program.

[0041] 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 a bus of the computer 200 or may be an external medium connected to the computer 200 via the interface 104 or a communication line. Further, when this program is delivered to the computer 200 through the communication line, the computer 200 to which the program is delivered may load the program into the main memory 102 and may perform the processing. The storage 103 is a non-transitory tangible storage medium.

[0042] Further, the above program may implement some of the above-mentioned functions. Furthermore, the program may be a so-called differential file (differential program) that can realize the above functions in combination with a program already recorded in the computer 200.

[0043] A custom large scale integrated circuit (LSI) such as a programmable logic device (PLD), an application specific integrated circuit (ASIC), a graphics processing unit (GPU), and a processing device similar thereto may be provided in addition to the above-described configuration or instead of the above-described configuration. As examples of the PLD, a programmable array logic (PAL), a generic array logic (GAL), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA) can be given. In this case, a part or all of the functions realized by the processor may be realized by the integrated circuit.<Additional Notes>

[0044] The air conditioning device described in each embodiment is understood as follows, for example.

[0045] (1) An air conditioner 1 according to a 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 that is disposed on the gas pipe 13, a liquid pipe 15 that connects the indoor heat exchanger 11 and the outdoor heat exchanger 12, through which a liquid-phase or gas-liquid two-phase refrigerant flows, and that forms a circulation circuit together with the gas pipe 13, an expansion valve 16 that is provided on the liquid pipe 15, a four-way valve that switches a flow direction of the refrigerant between a cooling operation and a heating operation, shutoff valves that are respectively provided on the gas pipe 13 and on the liquid pipe 15, a temperature measurement unit 41 that measures an outside air temperature, and a control device 50, in which the control device 50 includes a reception unit 51 that receives an operation stop command, a reading unit 52 that reads the outside air temperature, a charged refrigerant amount, and a predetermined refrigerant amount threshold value when the operation stop command is received, a refrigerant amount acquisition unit 53 that acquires an indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from an operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses, a comparison unit 54 that compares the indoor-side refrigerant amount with the refrigerant amount threshold value, and a determination unit 55 that determines whether to perform a cooling operation for transferring the refrigerant remaining on an indoor heat exchanger 11 side to an outdoor heat exchanger 12 side, based on a comparison result by the comparison unit 54.

[0046] According to the above-described configuration, when the operation stop command is issued during the heating operation, the determination unit 55 determines whether to perform the cooling operation for transferring the refrigerant remaining on the indoor heat exchanger 11 side to the outdoor heat exchanger 12 side. As a result, when the amount of the refrigerant remaining on the indoor heat exchanger 11 side is relatively small, the state in which the amount of the remaining refrigerant satisfies the predetermined standard is achieved without performing the cooling operation. Therefore, the possibility that the unnecessary cooling operation is performed is reduced, and it is possible to avoid a situation in which the air in the room heated by the heating operation is cooled again by the cooling operation.

[0047] (2) An air conditioner 1 according to a second aspect is the air conditioner 1 of (1), in which the determination unit 55 determines not to perform the cooling operation when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the elapsed time, and the control device 50 further includes a time acquisition unit 56 that acquires a shutoff time, which is a time until the shutoff valves are closed, and a valve drive unit 57 that closes the shutoff valves when the shutoff time elapses.

[0048] According to the above-described configuration, when the comparison unit 54 determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the predetermined elapsed times, the determination unit 55 determines not to perform the cooling operation. Accordingly, the possibility that the unnecessary cooling operation is performed can be further reduced.

[0049] (3) An air conditioner 1 according to a third aspect is the air conditioner 1 of (1) or (2), in which the determination unit 55 determines to start the cooling operation when the comparison unit 54 determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value.

[0050] According to the above-described configuration, when the comparison unit 54 determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value, it is possible to determine that the indoor-side refrigerant amount is excessive. Therefore, it is necessary to immediately reduce the indoor-side refrigerant amount by performing the cooling operation. According to the above-described configuration, such a determination can be immediately made by the determination unit 55.

[0051] (4) An air conditioner 1 according to a fourth aspect is the air conditioner 1 according to any one aspect of (1) to (3), in which in the table, a relationship between the elapsed time and the predicted value of the indoor-side refrigerant amount is predetermined for each of the outside air temperatures.

[0052] According to the above-described configuration, the relationship between the elapsed time and a predicted value of the indoor-side refrigerant amount is predetermined for each outside air temperature in the table. Therefore, it is possible to accurately predict the change in the indoor-side refrigerant amount for each elapsed time regardless of the change in the outside air temperature.

[0053] (5) An air conditioner 1 according to a fifth aspect is the air conditioner 1 of (2), further including: a leakage-detecting sensor 42 that detects leakage of the refrigerant into a room; and a sensor control unit 58 that is provided in the control device 50 and controls energization to the leakage-detecting sensor 42, in which the sensor control unit 58 stops the energization to the leakage-detecting sensor 42 after the shutoff valves are closed by the valve drive unit 57.

[0054] Here, the leakage-detecting sensor 42 generally operates in a state where a metal oxide is preheated. Therefore, when the preheating is continued for a long period of time, a metal oxide may deteriorate, and the function as the sensor may not be maintained. According to the above-described configuration, when the shutoff valve is closed and the condition in which the leakage of the refrigerant cannot occur is established, the sensor control unit 58 stops the energization to the leakage-detecting sensor. Therefore, the energization time to the leakage-detecting sensor 42 can be minimized.Industrial Applicability

[0055] According to the present disclosure, it is possible to provide an air conditioner that can be stably operated even in a case of the heating operation stop and that can ensure high habitability.Reference Signs List

[0056] 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 operation valve 30: second operation valve 41: temperature measurement unit 42: leakage-detecting sensor 50: control device 51: reception unit 52: reading unit 53: refrigerant amount acquisition unit 54: comparison unit 55: determination unit 56: time acquisition unit 57: valve drive unit 58: sensor control unit 59: storage unit 101: CPU 102: main memory 103: storage 104: interface 200: computer

Examples

Embodiment Construction

(Configuration of Air Conditioner)

[0010]Hereinafter, an air conditioner 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. As shown in FIG. 1, the air conditioner 1 includes a refrigeration cycle circuit 10, a first operation valve 20, a second operation valve 30, a temperature measurement unit 41, a leakage-detecting sensor 42, and a control device 50. It should be noted that the first operation valve 20 and the second operation valve 30 may be collectively referred to as a "shutoff valve".

(Refrigeration Cycle Circuit 10)

[0011]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).

[0012]The indoor heat exchanger 11 performs heat exchange between air in a room and a refrigerant. The indoor heat exchanger 11 is, for example, a heat exchanger of a fin-and-tube type or a plate type...

Claims

1. An air conditioner comprising: an indoor heat exchanger; an outdoor heat exchanger; a gas pipe that connects the indoor heat exchanger and the outdoor heat exchanger and through which a gas-phase refrigerant flows; a compressor that is 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 gas-liquid two-phase refrigerant flows, and that forms a circulation circuit together with the gas pipe; an expansion valve that is provided on the liquid pipe; a four-way valve that switches a flow direction of the refrigerant between a cooling operation and a heating operation; shutoff valves that are respectively provided on the gas pipe and on the liquid pipe; a temperature measurement unit that measures an outside air temperature; and a control device, wherein the control device includes a reception unit that receives an operation stop command, a reading unit that reads the outside air temperature, a charged refrigerant amount, and a predetermined refrigerant amount threshold value when the operation stop command is received, a refrigerant amount acquisition unit that acquires an indoor-side refrigerant amount for each elapsed time based on a table including a predetermined time from an operation stop and a ratio of a predicted value of the indoor-side refrigerant amount when the time elapses, a comparison unit that compares the indoor-side refrigerant amount with the refrigerant amount threshold value, and a determination unit that determines whether to perform a cooling operation for transferring the refrigerant remaining on an indoor heat exchanger side to an outdoor heat exchanger side, based on a comparison result by the comparison unit.

2. The air conditioner according to Claim 1, wherein the determination unit determines not to perform the cooling operation when the comparison unit determines that the indoor-side refrigerant amount is lower than the refrigerant amount threshold value at at least a part of the elapsed time, and the control device further includes a time acquisition unit that acquires a shutoff time, which is a time until the shutoff valves are closed, and a valve drive unit that closes the shutoff valves when the shutoff time elapses.

3. The air conditioner according to Claim 1 or 2, wherein the determination unit determines to start the cooling operation when the comparison unit determines that there is no elapsed time at which the indoor-side refrigerant amount is lower than the refrigerant amount threshold value.

4. The air conditioner according to Claim 1 or 2, wherein in the table, a relationship between the elapsed time and the predicted value of the indoor-side refrigerant amount is predetermined for each of the outside air temperatures.

5. The air conditioner according to Claim 2, further comprising: a leakage-detecting sensor that detects leakage of the refrigerant into a room; and a sensor control unit that is provided in the control device and controls energization to the leakage-detecting sensor, wherein the sensor control unit stops the energization to the leakage-detecting sensor after the shutoff valves are closed by the valve drive unit.

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