Refrigerant leakage determining device, air conditioner, refrigerant leakage determination program, and refrigerant leakage determination method

Abstract

This refrigerant leakage determining device determines a leak of refrigerant in an air conditioner that comprises an outdoor unit including a compressor, an outdoor heat exchanger, and an expansion valve, and an indoor unit including an indoor heat exchanger, and that is provided with a refrigerant circuit formed by connecting the outdoor unit and the indoor unit by refrigerant piping, the refrigerant circulating within the refrigerant circuit. The refrigerant leakage determining device includes a control portion equipped with a classification model that learns by associating at least two of a first state quantity indicating the state of the refrigerant in a condenser of the air conditioner, a second state quantity indicating the state of the refrigerant in an evaporator, and a third state quantity indicating the state of operation of the air conditioner, with the presence or absence a refrigerant leak. It is possible to determine whether or not the refrigerant circulating within the refrigerant circuit is leaking to the outside regardless of the type of air conditioner.

Description

Refrigerant leak detection device, air conditioner, refrigerant leak detection program, and refrigerant leak detection method

[0001] The present invention relates to a refrigerant leakage detection device, an air conditioner, a refrigerant leakage detection program, and a refrigerant leakage detection method.

[0002] For example, a refrigerant amount estimation device has been proposed that estimates the amount of refrigerant circulating in a refrigerant circuit using operational state quantities detectable in the refrigerant circuit. The refrigerant amount estimation device in Patent Document 1 learns the SC expansion valve opening and SC heat exchanger outlet temperature, among multiple operational state quantities detectable in the refrigerant circuit of an air conditioner equipped with a subcooling heat exchanger, in association with the refrigerant amount. The air conditioner then uses the refrigerant amount estimation device to estimate the amount of refrigerant circulating in the refrigerant circuit during operation using the SC expansion valve opening and SC heat exchanger outlet temperature during operation.

[0003] Japanese Patent Application Laid-Open No. 2020-153575

[0004] However, in the case of an air conditioner that does not have a subcooling heat exchanger, it is not possible to obtain the SC expansion valve opening and the SC heat exchanger outlet temperature. Therefore, in addition to an estimation model for an air conditioner that has a subcooling heat exchanger, it is necessary to prepare a refrigerant amount estimation device for an air conditioner that does not have a subcooling heat exchanger.

[0005] On the other hand, the purpose of estimating the refrigerant amount is to monitor whether the air conditioner is operating normally. In order to determine whether the air conditioner is operating normally, it is necessary to determine with high accuracy whether the refrigerant circulating in the refrigerant circuit is leaking to the outside before estimating the refrigerant amount. This is because if the refrigerant sealed in the air conditioner leaks to the outside, the air conditioner's heating and cooling capacity (the amount of heat energy removed from or added to the room per unit time) will decrease.

[0006] Therefore, it is required to be able to determine whether or not the refrigerant circulating in the refrigerant circuit is leaking to the outside, regardless of whether or not a subcooling heat exchanger is installed.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a refrigerant leakage detection device etc. that can determine whether or not refrigerant circulating in a refrigerant circuit is leaking to the outside, regardless of the type of air conditioner.

[0008] One embodiment of a refrigerant leakage detection device includes an outdoor unit having a compressor, an outdoor heat exchanger, and an expansion valve, and an indoor unit having an indoor heat exchanger, with the outdoor unit and the indoor unit being connected by refrigerant piping to form a refrigerant circuit. The refrigerant leakage detection device determines whether a refrigerant leaks in an air conditioner through which refrigerant circulates. The refrigerant leakage detection device has a control unit equipped with a classification model that learns by associating the presence or absence of a refrigerant leak with at least two state quantities out of a first state quantity indicating the state of the refrigerant in the condenser of the air conditioner, a second state quantity indicating the state of the refrigerant in the evaporator, and a third state quantity indicating the operating state of the air conditioner.

[0009] As one aspect, it is possible to determine whether or not refrigerant circulating in the refrigerant circuit is leaking to the outside, regardless of the type of air conditioner.

[0010] FIG. 1 is an explanatory diagram showing an example of an air conditioner of the present embodiment. FIG. 2 is an explanatory diagram showing an example of an outdoor unit and an indoor unit of Example 1. FIG. 3 is a block diagram showing an example of a first control unit of Example 1. FIG. 4 is a block diagram showing an example of a second control unit of Example 1. FIG. 5A is an explanatory diagram showing an example of an air conditioning system of a modified example. FIG. 5B is a block diagram showing an example of a third control unit of a modified example. FIG. 6 is a flowchart showing an example of processing operations of the first control unit related to the estimation processing of Example 1. FIG. 7 is a block diagram showing an example of a first control unit of Example 2. FIG. 8 is an explanatory diagram showing an example of feature amounts for each classification model type. FIG. 9 is a flowchart showing an example of processing operations of the first control unit related to the estimation processing of Example 2. FIG. 10 is an explanatory diagram showing an example of an outdoor unit and an indoor unit of Example 3.

[0011] Hereinafter, embodiments of the refrigerant leakage detection device and the like disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed technology is not limited to these embodiments. Furthermore, each of the embodiments described below may be modified as appropriate within the scope of the present invention.

[0012] <Configuration of Air Conditioner> Fig. 1 is an explanatory diagram showing an example of an air conditioner 1 of this embodiment. The air conditioner 1 shown in Fig. 1 has one outdoor unit 2 and N indoor units 3 (N is a natural number of 2 or more). The outdoor unit 2 is connected to each indoor unit 3 in parallel by liquid pipes 4 and gas pipes 5. The outdoor unit 2 and the indoor units 3 are connected by refrigerant piping such as the liquid pipes 4 and gas pipes 5, thereby forming a refrigerant circuit 6 of the air conditioner 1.

[0013] 2 is an explanatory diagram showing an example of the outdoor unit 2 and indoor unit 3 of Example 1. The outdoor unit 2 has a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an outdoor unit expansion valve 14, a first shut-off valve 15, a second shut-off valve 16, an accumulator 17, an outdoor unit fan 18, an injection circuit 19, and a first control unit 20. The compressor 11, the four-way valve 12, the outdoor heat exchanger 13, the outdoor unit expansion valve 14, the first shut-off valve 15, the second shut-off valve 16, the accumulator 17, and the injection circuit 19 are connected to each other by refrigerant piping to form an outdoor-side refrigerant circuit that forms part of the refrigerant circuit 6.

[0014] The compressor 11 is a high-pressure vessel type variable capacity compressor whose operating capacity can be varied in response to the drive of a motor (not shown) whose rotation speed is controlled by an inverter, for example. The refrigerant discharge side of the compressor 11 is connected to the first port 12A of the four-way valve 12 by a discharge pipe 21. The refrigerant suction side of the compressor 11 is also connected to the refrigerant outlet side of the accumulator 17 by a suction pipe 22.

[0015] The four-way valve 12 is a valve for switching the flow direction of the refrigerant in the refrigerant circuit 6 and includes first to fourth ports 12A to 12D. The first port 12A is connected to the refrigerant discharge side of the compressor 11 via a discharge pipe 21. The second port 12B is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 13 via an outdoor refrigerant pipe 23. The third port 12C is connected to the refrigerant inlet side of the accumulator 17 via an outdoor refrigerant pipe 26. The fourth port 12D is connected to the second stop valve 16 via an outdoor gas pipe 24.

[0016] The outdoor heat exchanger 13 exchanges heat between the refrigerant and outside air taken into the outdoor unit 2 by the rotation of the outdoor unit fan 18. One refrigerant inlet / outlet of the outdoor heat exchanger 13 is connected to the second port 12B of the four-way valve 12 by an outdoor refrigerant pipe 26. The other refrigerant inlet / outlet of the outdoor heat exchanger 13 is connected to the first stop valve 15 by an outdoor liquid pipe 25. The outdoor heat exchanger 13 functions as a condenser when the air conditioner 1 is in cooling operation, and functions as an evaporator when the air conditioner 1 is in heating operation.

[0017] The outdoor unit expansion valve 14 is provided in the outdoor liquid pipe 25 and is an electronic expansion valve driven by a pulse motor (not shown). The outdoor unit expansion valve 14 adjusts the amount of refrigerant flowing into or out of the outdoor heat exchanger 13 by adjusting its opening depending on the number of pulses applied to the pulse motor. When the air conditioner 1 is performing heating operation, the opening of the outdoor unit expansion valve 14 is adjusted so that the refrigerant superheat on the refrigerant suction side of the compressor 11 becomes a target suction refrigerant superheat. When the air conditioner 1 is performing cooling operation, the opening of the outdoor unit expansion valve 14 is fully open.

[0018] The refrigerant inlet side of the accumulator 17 is connected to the third port 12C of the four-way valve 12 by an outdoor refrigerant pipe 26. Furthermore, the refrigerant outlet side of the accumulator 17 is connected to the refrigerant inlet side of the compressor 11 by a suction pipe 22. The accumulator 17 separates the refrigerant that has flowed into the accumulator 17 from the outdoor refrigerant pipe 26 into gas refrigerant and liquid refrigerant, and allows only the gas refrigerant to be sucked into the compressor 11.

[0019] The outdoor unit fan 18 is made of a resin material and is disposed near the outdoor heat exchanger 13. In response to the rotation of a fan motor (not shown), the outdoor unit fan 18 takes in outside air from an air inlet (not shown) into the outdoor unit 2, and discharges the outside air that has exchanged heat with the refrigerant in the outdoor heat exchanger 13 to the outside of the outdoor unit 2 from an air outlet (not shown).

[0020] The injection circuit 19 has a branching section 19A, a subcooling (hereinafter simply referred to as SC) expansion valve 19B, an SC heat exchanger 19C, a mixing section 19D, and a bypass piping 19E. The branching section 19A is provided in the outdoor liquid pipe 25 between the outdoor unit expansion valve 14 and the SC heat exchanger 19C, and branches and outputs the refrigerant from the outdoor unit expansion valve 14 to the SC heat exchanger 19C and the SC expansion valve 19B. The SC expansion valve 19B is provided in the refrigerant pipe between the branching section 19A and the SC heat exchanger 19C, and is a subcooling expansion valve that adjusts the amount of refrigerant injected into the compressor 11. The SC expansion valve 19B opens and closes, and adjusts its opening degree according to the control of the first control unit 20.

[0021] The SC heat exchanger 19C is provided in the outdoor liquid pipe 25 between the outdoor unit expansion valve 14 and the first shut-off valve 15, and is a subcooling heat exchanger that converts two-phase gas-liquid refrigerant into single-phase liquid subcooled refrigerant.

[0022] The bypass piping 19E is a piping that allows a portion of the refrigerant flowing between the SC heat exchanger 19C and the first stop valve 15 to flow via the SC expansion valve 19B into the outdoor refrigerant pipe 26 that extends from the third port 12C of the four-way valve 12 to the accumulator 17. The mixing unit 19D is provided between the outdoor refrigerant pipe 26 and the bypass piping 19E. The mixing unit 19D mixes the refrigerant from the bypass piping 19E connected to the SC heat exchanger 19C with the refrigerant from the outdoor refrigerant pipe 26 via the third port 12C of the four-way valve 12, and inputs the mixed refrigerant to the refrigerant inlet side of the accumulator 17.

[0023] The SC heat exchanger 19C has a high-pressure side flow path and a low-pressure side flow path (not shown). The refrigerant that flows out from the outdoor unit expansion valve 14 when the indoor unit 3 is in cooling operation flows into the high-pressure side flow path. The refrigerant that flows into the high-pressure side flow path exchanges heat with the refrigerant in the low-pressure side flow path and then flows out to the first stop valve 15 side. The low-pressure side flow path is provided in the outdoor liquid pipe 25, and the refrigerant that flows out from the SC expansion valve 19B flows into it. The refrigerant that flows into the low-pressure side flow path exchanges heat with the refrigerant in the high-pressure side flow path and then flows out to the bypass pipe 19E.

[0024] Furthermore, the outdoor liquid pipe 25 is provided with an SC expansion valve 19B upstream of the SC heat exchanger 19C in the refrigerant flow direction when the indoor unit 3 is in heating operation. With these configurations, the section of the outdoor liquid pipe 25 downstream of the SC heat exchanger 19C becomes a flow path through which single-liquid-phase refrigerant flows. The flow path through which single-liquid-phase refrigerant flows corresponds to one section of the outdoor liquid pipe 25. When the indoor unit 3 is in cooling operation, the section of the outdoor liquid pipe 25 between the SC heat exchanger 19C and the first stop valve 15 is the flow path through which single-liquid-phase refrigerant flows. When the indoor unit 3 is in heating operation, the section of the outdoor liquid pipe 25 between the SC heat exchanger 19C and the outdoor unit expansion valve 14 is the flow path through which single-liquid-phase refrigerant flows.

[0025] In addition, a plurality of sensors are arranged in the outdoor unit 2. A discharge pressure sensor 31 that detects the pressure of the refrigerant discharged from the compressor 11, i.e., the discharge pressure, and a discharge temperature sensor 32 that detects the temperature of the refrigerant discharged from the compressor 11, i.e., the discharge temperature, are arranged in the discharge pipe 21. A suction pressure sensor 33 that detects the suction pressure, which is the pressure of the refrigerant sucked into the compressor 11, and a suction temperature sensor 34 that detects the temperature of the refrigerant sucked into the compressor 11 are arranged near the refrigerant inlet of the accumulator 17 in the outdoor refrigerant pipe 26.

[0026] A refrigerant temperature sensor 35 is disposed in the outdoor liquid pipe 25 between the outdoor heat exchanger 13 and the outdoor unit expansion valve 14 to detect the temperature of the refrigerant flowing into the outdoor heat exchanger 13 or the temperature of the refrigerant flowing out of the outdoor heat exchanger 13. An outdoor air temperature sensor 36 is disposed near an air inlet (not shown) of the outdoor unit 2 to detect the temperature of the outdoor air flowing into the outdoor unit 2, i.e., the outdoor air temperature.

[0027] The first control unit 20 controls the entire air conditioner 1. FIG. 3 is a block diagram showing an example of the first control unit 20 of the first embodiment. The first control unit 20 has a first communication unit 41, a first acquisition unit 42, a first storage unit 43, and a first control unit 44. The first acquisition unit 42 acquires sensor values ​​from the various sensors described above. The first communication unit 41 is a communication interface that communicates with the second communication unit 71 of each indoor unit 3. The first storage unit 43 is, for example, a flash memory. The first storage unit 43 stores the control program for the outdoor unit 2, operating state quantities such as detected values ​​corresponding to detection signals from the various sensors, the driving states of the compressor 11 and the outdoor unit fan 18, operating information transmitted from each indoor unit 3 (including, for example, operation / stop information, operating modes such as cooling / heating, etc.), the rated capacity of the outdoor unit 2, and the required capacity of each indoor unit 3.

[0028] The first storage unit 43 also stores a classification model 430 that determines whether or not there is a refrigerant leak in the refrigerant circuit 6. In this embodiment, for example, a relative amount of refrigerant is used as the amount of refrigerant remaining in the refrigerant circuit 6. Specifically, the first storage unit 43 stores a classification model that determines whether or not the amount of refrigerant remaining in the refrigerant circuit 6 is appropriate based on predetermined operating state quantities, which will be described later.

[0029] The first control unit 44 periodically (for example, every 30 seconds) retrieves detection values ​​from various sensors via the first communication unit 41, and receives signals containing operation information transmitted from each indoor unit 3 via the first communication unit 41. Based on this input information, the first control unit 44 adjusts the opening of the outdoor unit expansion valve 14 and controls the drive of the compressor 11. Furthermore, the first control unit 44 is a refrigerant leakage determination device that determines the presence or absence of a refrigerant leak in the refrigerant circuit 6 using the classification model 430 described above. In other words, the first control unit 44 determines the presence or absence of a refrigerant leak in the air conditioner 1 in which refrigerant circulates within the refrigerant circuit 6.

[0030] 2 , the indoor unit 3 has an indoor heat exchanger 51, an indoor unit expansion valve 52, a liquid pipe connection 53, a gas pipe connection 54, an indoor unit fan 55, and a second control unit 50. The indoor heat exchanger 51, the indoor unit expansion valve 52, the liquid pipe connection 53, and the gas pipe connection 54 are connected to each other by refrigerant pipes described later, and constitute an indoor unit refrigerant circuit that forms part of the refrigerant circuit 6.

[0031] The indoor heat exchanger 51 exchanges heat between the refrigerant and indoor air drawn into the indoor unit 3 through an air inlet (not shown) by the rotation of the indoor unit fan 55. One refrigerant inlet / outlet of the indoor heat exchanger 51 is connected to a liquid pipe connection part 53 by an indoor liquid pipe 56. The other refrigerant inlet / outlet of the indoor heat exchanger 51 is connected to a gas pipe connection part 54 by an indoor gas pipe 57. The indoor heat exchanger 51 functions as a condenser when the air conditioner 1 is performing heating operation. On the other hand, the indoor heat exchanger 51 functions as an evaporator when the air conditioner 1 is performing cooling operation.

[0032] The indoor unit expansion valve 52 is an electronic expansion valve and is provided in the indoor liquid pipe 56. When the indoor heat exchanger 51 functions as an evaporator, i.e., when the indoor unit 3 is performing cooling operation, the opening degree of the indoor unit expansion valve 52 is adjusted so that the refrigerant superheat degree at the refrigerant outlet (gas pipe connection 54 side) of the indoor heat exchanger 51 becomes a target refrigerant superheat degree. When the indoor heat exchanger 51 functions as a condenser, i.e., when the indoor unit 3 is performing heating operation, the opening degree of the indoor unit expansion valve 52 is adjusted so that the refrigerant subcooling degree at the refrigerant outlet (liquid pipe connection 53 side) of the indoor heat exchanger 51 becomes a target refrigerant subcooling degree. Here, the target refrigerant superheat degree and the target refrigerant subcooling degree are the refrigerant superheat degree and the refrigerant subcooling degree required for the indoor unit 3 to exhibit sufficient cooling or heating capacity.

[0033] The indoor unit fan 55 is made of a resin material and is disposed near the indoor heat exchanger 51. The indoor unit fan 55 is rotated by a fan motor (not shown) to take in indoor air into the indoor unit 3 through an intake port (not shown), and releases the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 51 into the room through an outlet port (not shown).

[0034] Various sensors are provided in the indoor unit 3. A liquid-side refrigerant temperature sensor 61 is disposed in the indoor liquid pipe 56, between the indoor heat exchanger 51 and the indoor unit expansion valve 52, to detect the temperature of the refrigerant flowing into the indoor heat exchanger 51 or the indoor heat exchanger outlet temperature, which is the temperature of the refrigerant flowing out from the indoor heat exchanger 51. A gas-side temperature sensor 62 is disposed in the indoor gas pipe 57 to detect the temperature of the refrigerant flowing out from or into the indoor heat exchanger 51. A suction temperature sensor 63 is disposed near an air inlet (not shown) of the indoor unit 3 to detect the temperature of the indoor air flowing into the indoor unit 3, i.e., the suction temperature.

[0035] The second control unit 50 controls the entire indoor unit 3. FIG. 4 is a block diagram showing an example of the second control unit 50 of the first embodiment. The second control unit 50 has a second communication unit 71, a second acquisition unit 72, a second storage unit 73, and a second control unit 74. The second acquisition unit 72 acquires sensor values ​​from various sensors in the indoor unit 3. The second communication unit 71 is a communication interface that communicates with the first communication unit 41 of the outdoor unit 2. The second storage unit 73 is, for example, a flash memory. The second storage unit 73 stores the control program for the indoor unit 3, operation state quantities such as detected values ​​corresponding to detection signals from the various sensors, the drive state of the indoor unit fan 55, operation information of the indoor unit 3 (including, for example, operation / stop information, operation modes such as cooling / heating, etc.), and the required capacity of each indoor unit 3.

[0036] The second control unit 74 periodically (for example, every 30 seconds) transmits detected values ​​of various sensors in the indoor unit 3 to the first control unit 20 of the outdoor unit 2 via the second communication unit 71. The second control unit 74 adjusts the opening degree of the indoor unit expansion valve 52 based on the various types of input information.

[0037] <Operation of Refrigerant Circuit> Next, a description will be given of the flow of refrigerant in the refrigerant circuit 6 and the operation of each part during air conditioning operation of the air conditioner 1 in this embodiment. Note that the arrows in Fig. 2 indicate the flow of refrigerant during heating operation.

[0038] When the air conditioner 1 performs heating operation, the four-way valve 12 is switched so that the first port 12A and the fourth port 12D are connected and the second port 12B and the third port 12C are connected. As a result, the refrigerant circuit 6 becomes a heating cycle in which each indoor heat exchanger 51 functions as a condenser and the outdoor heat exchanger 13 functions as an evaporator. For ease of explanation, the flow of refrigerant during heating operation is indicated by solid arrows in Figure 2.

[0039] When the compressor 11 is driven with the refrigerant circuit 6 in the above state, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 and into the four-way valve 12, then flows from the four-way valve 12 through the outdoor gas pipe 24 and into the gas pipe 5 via the second shut-off valve 16. The refrigerant flowing through the gas pipe 5 is diverted to each indoor unit 3 via each gas pipe connection 54. The refrigerant that flows into each indoor unit 3 flows through each indoor gas pipe 57 and into each indoor heat exchanger 51. The refrigerant that flows into each indoor heat exchanger 51 condenses by exchanging heat with indoor air drawn into each indoor unit 3 by the rotation of each indoor unit fan 55. In other words, each indoor heat exchanger 51 functions as a condenser, and the indoor air heated by the refrigerant in each indoor heat exchanger 51 is blown into the room through an air outlet (not shown), thereby heating the room in which each indoor unit 3 is installed.

[0040] The refrigerant that flows from each indoor heat exchanger 51 into each indoor liquid pipe 56 is decompressed by passing through each indoor unit expansion valve 52, the opening of which is adjusted so that the degree of refrigerant subcooling at the refrigerant outlet side of each indoor heat exchanger 51 becomes the target degree of refrigerant subcooling. Here, the target degree of refrigerant subcooling is determined based on the cooling capacity required by each indoor unit 3.

[0041] The refrigerant decompressed by each indoor unit expansion valve 52 flows from each indoor liquid pipe 56 through each liquid pipe connection 53 into the liquid pipe 4. The refrigerant joined in the liquid pipe 4 flows into the outdoor unit 2 through the first shut-off valve 15. The refrigerant that flows into the first shut-off valve 15 of the outdoor unit 2 flows through the outdoor liquid pipe 25 and into the SC heat exchanger 19C. The high-pressure refrigerant that flows into the SC heat exchanger 19C is thermally converted into single-phase liquid refrigerant through the SC heat exchanger 19C, and the converted single-phase liquid refrigerant flows into the outdoor unit expansion valve 14. The refrigerant that flows into the outdoor unit expansion valve 14 then passes through the outdoor unit expansion valve 14 and is decompressed. The refrigerant that has been decompressed by the outdoor unit expansion valve 14 flows through the outdoor liquid pipe 25 and into the outdoor heat exchanger 13, where it exchanges heat with outside air that flows in through an intake port (not shown) of the outdoor unit 2 due to the rotation of the outdoor unit fan 18, and evaporates. The refrigerant that flows out from the outdoor heat exchanger 13 to the outdoor refrigerant pipe 26 flows in the following order: the four-way valve 12, the outdoor refrigerant pipe 26, the accumulator 17, and the suction pipe 22. The refrigerant is then drawn into the compressor 11 and compressed again, and flows out into the outdoor gas pipe 24 via the first port 12A and the fourth port 12D of the four-way valve 12.

[0042] When the air conditioner 1 is in cooling operation, the four-way valve 12 is switched so that the first port 12A and the second port 12B are in communication, and the third port 12C and the fourth port 12D are in communication. As a result, the refrigerant circuit 6 becomes a cooling cycle in which each indoor heat exchanger 51 functions as an evaporator and the outdoor heat exchanger 13 functions as a condenser. For ease of explanation, the flow of refrigerant during cooling operation is indicated by dashed arrows in Figure 2.

[0043] When the compressor 11 is driven in the refrigerant circuit 6, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 and into the four-way valve 12, and then flows from the four-way valve 12 through the outdoor refrigerant pipe 26 and into the outdoor heat exchanger 13. The refrigerant that has flowed into the outdoor heat exchanger 13 condenses by exchanging heat with outdoor air that has been drawn into the outdoor unit 2 by the rotation of the outdoor unit fan 18. In other words, the outdoor heat exchanger 13 functions as a condenser, and the indoor air heated by the refrigerant in the outdoor heat exchanger 13 is blown outside through an air outlet (not shown).

[0044] The refrigerant flowing from the outdoor heat exchanger 13 into the outdoor liquid pipe 25 is decompressed as it passes through the outdoor unit expansion valve 14, which is fully open. The refrigerant decompressed by the outdoor unit expansion valve 14 flows into the SC heat exchanger 19C via the branching section 19A. The SC heat exchanger 19C exchanges heat between the refrigerant that passed through the SC expansion valve 19B and the refrigerant flowing through the outdoor liquid pipe 25, thereby converting the high-pressure refrigerant into a single-phase liquid refrigerant. The refrigerant that has undergone heat exchange in the SC heat exchanger 19C flows through the first stop valve 15 into the liquid pipe 4 and is diverted to each indoor unit 3. The refrigerant that has flowed into each indoor unit 3 flows through each liquid pipe connection section 53 into the indoor liquid pipe 56, and is decompressed as it passes through the indoor unit expansion valve 52, which has an opening adjusted to achieve a target refrigerant subcooling degree at the refrigerant outlet of the indoor heat exchanger 51. The refrigerant decompressed by the indoor unit expansion valve 52 flows through the indoor liquid pipe 56 and into the indoor heat exchanger 51, where it evaporates by exchanging heat with indoor air that has flowed in from an intake port (not shown) of the indoor unit 3 due to the rotation of the indoor unit fan 55. In other words, each indoor heat exchanger 51 functions as an evaporator, and the indoor air cooled by the refrigerant in each indoor heat exchanger 51 is blown out into the room from an outlet (not shown), thereby cooling the room in which each indoor unit 3 is installed.

[0045] The refrigerant flowing from the indoor heat exchanger 51 to the gas pipe 5 via the gas pipe connection part 54 flows through the second shut-off valve 16 of the outdoor unit 2 to the outdoor gas pipe 24 and flows into the fourth port 12D of the four-way valve 12. The refrigerant that has flowed into the fourth port 12D of the four-way valve 12 flows from the third port 12C into the refrigerant inlet side of the accumulator 17. The refrigerant that has flowed into the refrigerant inlet side of the accumulator 17 flows through the suction pipe 22 and is sucked into the compressor 11 to be compressed again.

[0046] The first acquisition unit 42 in the first control unit 20 acquires the sensor values ​​of the discharge pressure sensor 31, discharge temperature sensor 32, suction pressure sensor 33, suction temperature sensor 63, refrigerant temperature sensor 35, and outside air temperature sensor 36 in the outdoor unit 2. Furthermore, the first acquisition unit 42 acquires the sensor values ​​of the liquid side refrigerant temperature sensor 61, gas side temperature sensor 62, and suction temperature sensor 63 of each indoor unit 3.

[0047] During cooling operation of the air conditioner 1, the outdoor heat exchanger 13 functions as a condenser, and the indoor heat exchanger 51 functions as an evaporator. During heating operation of the air conditioner 1, the outdoor heat exchanger 13 functions as an evaporator, and the indoor heat exchanger 51 functions as a condenser.

[0048] The compressor 11 compresses the low-temperature, low-pressure gas refrigerant flowing in from the evaporator and discharges the high-temperature, high-pressure gas refrigerant. The temperature of the gas refrigerant discharged from the compressor 11 is the discharge temperature, which is detected by a discharge temperature sensor 32.

[0049] The condenser condenses the high-temperature, high-pressure gas refrigerant from the compressor 11 by exchanging heat with air. During this process, after the gas refrigerant has completely turned into liquid refrigerant due to latent heat change in the condenser, the temperature of the liquid refrigerant drops due to sensible heat change, resulting in a supercooled state. The temperature at which the gas refrigerant is changing into liquid refrigerant due to latent heat change is the high-pressure saturation temperature, and the temperature of the refrigerant in the supercooled state at the outlet of the condenser is the heat exchanger outlet temperature. The high-pressure saturation temperature is a temperature equivalent to the pressure value (HPS) detected by the discharge pressure sensor 31. The heat exchanger outlet temperature is detected by the refrigerant temperature sensor 35.

[0050] The expansion valve reduces the pressure of the low-temperature, high-pressure refrigerant that has flowed out of the condenser, and turns it into a gas-liquid two-phase refrigerant in which gas and liquid are mixed.

[0051] The evaporator evaporates the two-phase gas-liquid refrigerant that has flowed in through heat exchange with air. During this process, after the two-phase gas-liquid refrigerant in the evaporator has completely changed to gas refrigerant due to latent heat change, the temperature of the gas refrigerant rises due to sensible heat change, becoming superheated, and is then drawn into the compressor 11. The temperature at which the liquid refrigerant is changing to gas refrigerant due to latent heat change is the low-pressure saturation temperature. The low-pressure saturation temperature is a temperature corresponding to the pressure value (LPS) detected by the suction pressure sensor 33. The temperature of the refrigerant that has been superheated in the evaporator and is drawn into the compressor 11 is the suction temperature. The suction temperature is detected by the suction temperature sensor 34.

[0052] The degree of subcooling of the refrigerant that is in a subcooled state when it flows out of the condenser is the heat exchange subcool, which can be calculated by subtracting the refrigerant temperature at the refrigerant outlet of the heat exchanger functioning as a condenser (the heat exchange outlet temperature) from the high-pressure saturation temperature. The degree of superheat of the refrigerant that is in a superheated state when it flows out of the evaporator is the suction superheat, which can be calculated by subtracting the suction temperature from the low-pressure saturation temperature.

[0053] <Configuration and Generation of Classification Model> The classification model 430 is generated in advance by a classification algorithm using machine learning, using a plurality of operating state quantities. The operating state quantities include a first operating state quantity indicating the state of the refrigerant in the condenser, a second operating state quantity indicating the state of the refrigerant in the evaporator, and a third operating state quantity indicating the operating state of the air conditioner 1.

[0054] Nonlinear algorithms such as random forests and neural networks are used in classification algorithms. Nonlinear algorithms can be used to determine refrigerant leaks by combining values ​​that are not linearly proportional to the remaining refrigerant volume. For example, random forests are an ensemble learning method that combines multiple decision trees. Each tree learns independently, and classification is ultimately performed by majority vote or average. This prevents overfitting and improves the model's predictive accuracy. On the other hand, neural networks are deep learning models consisting of multiple layers: an input layer, one or more hidden layers, and an output layer. Each layer consists of multiple nodes (neurons), and information is transmitted between nodes in adjacent layers via weighted connections. Neural networks are well-suited to advanced classification problems due to their ability to capture nonlinear relationships and complex patterns.

[0055] To generate the classification model 430, first, the relationship between each operation state variable and the remaining refrigerant amount is reproduced on a computer, and a numerical calculation (hereinafter also referred to as a simulation) is performed. The simulation generates numerical data (also referred to as data points) that summarize the relationship between each operation state variable and the remaining refrigerant amount for each predetermined time period. Each operation state variable is changed under conditions that vary the remaining refrigerant amount (e.g., 40%, 70%, 80%, 100%, 120%, etc.), and multiple data points are generated by simulating refrigerant leaks and refrigerant overfilling in the air conditioner. The entire data consisting of these data points is stored as a data set in the computer's memory.

[0056] Next, this data set is used to train a classification model by machine learning, generating a classification model that classifies whether or not a refrigerant leaks based on the operating state quantities. In training the classification model, for example, if the remaining refrigerant amount is 80% or more, it is labeled as "no refrigerant leak," and if the refrigerant amount is less than 80%, it is labeled as "refrigerant leak." Indicators such as precision, recall, and F1 score are used to evaluate the classification model. Finally, the optimal model is selected as the classification model 430 based on these indices.

[0057] For example, the classification model 430 receives as input a first operating state quantity (the state of the refrigerant in the condenser), a second operating state quantity (the state of the refrigerant in the evaporator), and a third operating state quantity (the operating state of the air conditioner), and classifies the presence or absence of a refrigerant leak by combining this information. The classification model 430 generated in this manner can accurately recognize different patterns of the operating state quantities and correctly estimate the presence or absence of a refrigerant leak.

[0058] The first state quantity is, for example, a high-pressure saturation temperature corresponding to the pressure value detected by the discharge pressure sensor 31, a heat exchanger outlet temperature detected by the refrigerant temperature sensor 35, a condenser inlet refrigerant temperature which is the temperature of the refrigerant at the inlet of the condenser using a sensor, etc. Note that, instead of the high-pressure saturation temperature, the first state quantity may be, for example, a heat exchanger intermediate temperature which is the temperature of the refrigerant flowing inside the indoor heat exchanger 51 when it functions as a condenser, and can be changed as appropriate.

[0059] The second state quantity is, for example, the suction temperature detected by the suction temperature sensor 34, the low-pressure saturation temperature which is a temperature corresponding to the pressure value detected by the suction pressure sensor 33, the evaporator outlet refrigerant temperature which is the temperature of the refrigerant at the outlet of the evaporator using a sensor, etc. Note that, instead of the low-pressure saturation temperature, the second state quantity may be, for example, the heat exchange intermediate temperature which is the temperature of the refrigerant flowing inside the outdoor heat exchanger 13 when it functions as an evaporator, and can be changed as appropriate.

[0060] The third state quantity is, for example, the rotation speed of the compressor 11. Note that, instead of the rotation speed of the compressor 11, the opening degree of the indoor unit expansion valve 52, the opening degree of the outdoor unit expansion valve 14, the opening degree of the SC expansion valve 19B, or the like may be used as the third state quantity, and can be changed as appropriate.

[0061] The classification model 430 is generated using, for example, three operating state quantities, namely, the rotation speed, degree of subcooling, and degree of superheat of the compressor 11, as well as the outdoor air temperature. The rotation speed of the compressor 11 is detected by a rotation speed sensor (not shown) of the compressor 11. The degree of subcooling is calculated based on the heat exchanger outlet temperature of the condenser and the high-pressure saturation temperature of the condenser when the outdoor heat exchanger 13 functions as a condenser. That is, the degree of subcooling can be calculated, for example, as (high-pressure saturation temperature - heat exchanger outlet temperature). The high-pressure saturation temperature is a temperature corresponding to the pressure value detected by the discharge pressure sensor 31. The heat exchanger outlet temperature during cooling operation is the outdoor heat exchanger outlet temperature detected by the refrigerant temperature sensor 35. The heat exchanger outlet temperature during heating operation is the indoor heat exchanger outlet temperature detected by the liquid-side refrigerant temperature sensor 61. There are two degrees of subcooling: one used during cooling operation and one used during heating operation. The degree of subcooling during cooling operation can be calculated as (high-pressure saturation temperature - outdoor heat exchanger outlet temperature). In this embodiment, there is one outdoor unit 2, but if multiple outdoor units are connected, a representative outdoor unit can be selected and its operating state quantity can be used. The degree of subcooling during heating operation can be calculated by (high-pressure saturation temperature - indoor heat exchanger outlet temperature). In this embodiment, multiple indoor units 3 are connected to one outdoor unit 2. In this case, the degree of subcooling is calculated using the operating state quantity of the indoor unit that is operating among the multiple indoor units 3. Note that the heat load (cooling capacity) that can be processed may differ for each operating indoor unit. In this case, it is advisable to use a weighted average value in which the operating state quantities of the operating indoor units are weighted by their cooling capacity.

[0062] The degree of superheat is calculated based on the suction temperature of the compressor 11 and the low-pressure saturation temperature of the compressor 11 when the outdoor heat exchanger 13 functions as an evaporator. Specifically, the degree of superheat can be calculated as (suction temperature - low-pressure saturation temperature), where the suction temperature is detected by the suction temperature sensor 34 and the low-pressure saturation temperature is a temperature corresponding to the pressure value detected by the suction pressure sensor 33. The outside air temperature is detected by the outside air temperature sensor 36.

[0063] The classification model 430 is generated using these operating state variables with machine learning techniques based on nonlinear algorithms, such as random forests and neural networks. This enables more accurate determination of the presence or absence of a refrigerant leak in the refrigerant circuit. Random forests are ensemble learning models composed of numerous decision trees, each of which is trained based on a different subset of a data set. On the other hand, neural networks are deep learning models with multiple layers that are suitable for modeling highly nonlinear relationships. The classification model 430 can be generated using not only simulation results but also actual operating data to learn the relationship between each state variable (subcooling degree, superheat degree, compressor rotation speed, and outdoor air temperature) during cooling and heating operation and the presence or absence of a refrigerant leak. During this process, parameters are adjusted to optimize the model's performance.

[0064] Examples of classification models generated in this manner include a classification model 430A used during cooling operation and a classification model 430B used during heating operation. Classification model 430A outputs whether or not there is a refrigerant leak when operation data, such as the rotation speed of compressor 11 during cooling operation, the outside air temperature, and the degree of subcooling and superheat during cooling operation, are input as explanatory variables. Classification model 430B outputs whether or not there is a refrigerant leak when operation data, such as the rotation speed of compressor 11 during heating operation, the outside air temperature, and the degree of subcooling and superheat during heating operation, are input as explanatory variables.

[0065] In this embodiment, the classification models 430 (classification models 430A and 430B) are stored in the first control unit 20 of the outdoor unit 2 of the air conditioner 1. In the first control unit 20, the operating state quantities acquired by the first communication unit 41 and the first acquisition unit 42 are input to the classification model 430. The classification model 430 determines in real time whether or not there is a refrigerant leak based on the input values.

[0066] By generating and applying the classification model 430, the refrigerant leakage detection device is able to determine whether or not there is a refrigerant leak in the refrigerant circuit, thereby contributing to improving the operational efficiency and safety of the air conditioner. For example, the classification model 430 receives as input a first operating state quantity (the state of the refrigerant in the condenser), a second operating state quantity (the state of the refrigerant in the evaporator), and a third operating state quantity (the operating state of the air conditioner), and combines this information to determine whether or not there is a refrigerant leak.

[0067] In this way, the classification model 430 generated by the nonlinear algorithm can accurately recognize different patterns of the operating state quantities and correctly determine whether or not there is a refrigerant leak.

[0068] As described above, during cooling operation, the presence or absence of a refrigerant leak is determined using the classification model used during cooling operation. During heating operation, the presence or absence of a refrigerant leak is determined using the classification model used during heating operation. This makes it possible to determine the presence or absence of a refrigerant leak in the refrigerant circuit 6 during both cooling and heating operation.

[0069] Fig. 5A is an explanatory diagram showing an example of a modified air conditioning system 100. This illustrates a case where a classification model 430 is generated by a server device 110 and stored in a centralized controller 7. The air conditioning system 100 shown in Fig. 5A includes an air conditioner 1, a centralized controller 7, a server device 110, and a communication network 120. The server device 110 is a server device that generates and stores a learning model of the air conditioner 1 included in the air conditioning system 100. The communication network 120 is, for example, a communication network such as the Internet.

[0070] The centralized controller 7 has a third control unit 80. Fig. 5B is a block diagram showing an example of the third control unit 80 of a modified example. The third control unit 80 has a third communication unit 81, a third acquisition unit 82, a third storage unit 83, and a third control unit 84. The third acquisition unit 82 acquires sensor values ​​from the various sensors described above. The third communication unit 81 is a communication interface that communicates with the first communication unit 41 of the outdoor unit 2. The third storage unit 83 is, for example, a flash memory.

[0071] The third control unit 84 periodically (for example, every 30 seconds) takes in detected values ​​from various sensors via the third communication unit 81, and signals including operation information transmitted from the outdoor unit 2 and each indoor unit 3 are input via the third communication unit 81. In the case of the air conditioning system 100 shown in Fig. 5A, the third control unit 84 is a refrigerant leakage determination device that uses the stored classification model 430 to determine whether or not there is a refrigerant leak in the refrigerant circuit 6. In other words, the third control unit 84 determines whether or not there is a refrigerant leak in the air conditioner 1 in which refrigerant circulates in the refrigerant circuit 6.

[0072] <Operation of Estimation Processing> Figure 6 is a flowchart showing an example of the processing operation of the first control unit 20 related to the estimation processing of Example 1. It is assumed that the first control unit 20 stores a classification model 430 generated in advance to be used during cooling operation and heating operation. In Figure 6, the first control unit 44 in the first control unit 20 collects operating state quantities as operating data via the first acquisition unit 42 (step S21). The first control unit 44 then executes a data filtering process to extract any operating state quantity from the collected operating data (step S22). Furthermore, the first control unit 44 then executes a data cleansing process (step S23).

[0073] The data filtering process does not use all of the multiple operating state quantities, but extracts only a portion of the multiple operating state quantities necessary to determine the presence or absence of a refrigerant leak based on predetermined filter conditions. By substituting the operating state quantities that have been subjected to the data filtering process (with abnormal values ​​and outliers removed) into the generated classification model 430, the presence or absence of a refrigerant leak can be determined more accurately.

[0074] The predetermined filter condition is, for example, a filter condition for data extracted in common for all operation modes of the air conditioner 1. The predetermined filter condition is, for example, the operating state of the compressor 11, identification of the operating mode, elimination of special operations, elimination of missing values ​​in the acquired values, selection of values ​​with small variations for operating state quantities that have a large impact on the generation of the classification model, etc. The operating state of the compressor 11 is a condition that must be determined because the presence or absence of a refrigerant leak cannot be determined unless the compressor 11 is operating stably and refrigerant is circulating in the refrigerant circuit 6, and is a filter condition set to exclude operating state quantities detected during a transition period, such as when the compressor 11 is starting up.

[0075] The operation mode identification is a filter condition for extracting only the operation state quantities acquired during cooling operation and heating operation. Therefore, the operation state quantities acquired during dehumidification operation and ventilation operation are excluded. The special operation exclusion is a filter condition for excluding the operation state quantities acquired during special operation, such as oil recovery operation and defrosting operation, in which the state of the refrigerant circuit 6 is significantly different from that during cooling operation and heating operation. The missing value exclusion is a filter condition for excluding the operation state quantities containing missing values, because if the operation state quantities used to determine a refrigerant leak contain missing values, generating a classification model using those operation state quantities may result in a decrease in accuracy.

[0076] Selecting values ​​with small changes for the operating state quantities to be substituted into the classification model is a filter condition that extracts only the operating state quantities when the operating state of the air conditioner 1 is stable, and is a necessary condition for improving the estimation accuracy using the classification model.

[0077] The data cleansing process is a process for excluding operating state variables that may lead to an incorrect determination, rather than using all acquired operating state variables to determine whether or not a refrigerant leak exists. Specifically, the acquired operating state variables are smoothed to suppress noise and limit the number of data items. Noise suppression through data smoothing is a process for suppressing noise by calculating average values ​​for the relevant interval and taking moving averages of, for example, the degree of subcooling, intake temperature, and degree of superheat in each model. Limiting the number of data items is a process for excluding data items with a small number of items because they are unreliable. For example, if the number of remaining data items after filtering one day's worth of input data is X or more, they are used to estimate the refrigerant shortage rate; if the number is less than that, none of the data for that day is used. In other words, the data cleansing process allows for a more accurate determination of whether or not a refrigerant leak exists by substituting operating state variables, from which abnormal values ​​and outliers have been removed, into the classification model 430.

[0078] Furthermore, as part of the data cleansing process, the first control unit 44 extracts the current rotation speed of the compressor 11, the current outdoor air temperature, the current degree of subcooling, and the current degree of superheating, and then calculates the theoretical discharge temperature of the compressor 11 based on the high-pressure saturation temperature of the outdoor heat exchanger 13, the low-pressure saturation temperature of the outdoor heat exchanger 13, and the suction temperature of the compressor 11. The first control unit 44 then compares the calculated theoretical discharge temperature with the actual discharge temperature. The first control unit 44 then deletes from the extracted data the current rotation speed of the compressor 11, the current outdoor air temperature, the current degree of subcooling, and the current degree of superheating extracted when the theoretical discharge temperature exceeds the actual discharge temperature. The first control unit 44 also substitutes the current rotation speed of the compressor 11, the current outdoor air temperature, the current degree of subcooling, and the current degree of superheating extracted when the theoretical discharge temperature is equal to or lower than the actual discharge temperature into the classification model 430.

[0079] 6 , the first control unit 44 extracts the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling, and the degree of superheating from the operating data after the cleansing process (step S24). The first control unit 44 then assigns the extracted operating data of the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling, and the degree of superheating to the classification model 430 (step S25). For example, during cooling operation, the first control unit 44 assigns the operating data of the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling, and the degree of superheating during cooling operation to the classification model 430A used during cooling operation. Furthermore, during heating operation, the first control unit 44 assigns the operating data of the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling, and the degree of superheating during heating operation to the classification model 430B used during heating operation.

[0080] The first control unit 44 obtains a determination result of whether or not there is a refrigerant leak in the refrigerant circuit 6 using the classification model after the operating data has been substituted (step S26). That is, the first control unit 44 determines whether or not there is a refrigerant leak in the refrigerant circuit 6 during cooling operation using the classification model 430A used during cooling operation. The first control unit 44 also determines whether or not there is a refrigerant leak in the refrigerant circuit 6 during heating operation using the classification model 430B used during heating operation. The first control unit 44 determines whether or not there is a refrigerant leak as a result of the determination (step S27).

[0081] If the determination result indicates that a refrigerant leak exists (step S27: Yes), the first control unit 44 outputs a notification indicating that a refrigerant leak exists (step S28), and ends the processing operation shown in Fig. 6. If the determination result indicates that a refrigerant leak does not exist (step S27: No), the first control unit 44 outputs a notification indicating that no refrigerant leak exists (step S29), and ends the processing operation shown in Fig. 6.

[0082] Effect of First Embodiment In the air conditioner 1 of the first embodiment, a classification model 430 is generated using a nonlinear algorithm using operating state quantities related to determining whether or not there is a refrigerant leak in the refrigerant circuit 6, such as the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling, and the degree of superheat. As a result, it is possible to generate a classification model 430 that can determine whether or not there is a leak of the refrigerant circulating in the refrigerant circuit 6, without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0083] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the classification model 430 and the current rotation speed, outside air temperature, degree of subcooling, and degree of superheat of the compressor 11. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0084] In the air conditioner 1, a classification model 430A is generated by a nonlinear algorithm using operating state quantities during cooling operation related to determining the presence or absence of refrigerant leakage in the refrigerant circuit 6, such as the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling and superheat during cooling operation, and the presence or absence of refrigerant leakage. As a result, a classification model 430A can be generated that can determine the presence or absence of refrigerant leakage circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0085] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the classification model 430A for cooling operation, the current rotation speed of the compressor 11 during cooling operation, the outside air temperature, and the degree of subcooling and superheat during cooling operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0086] In the air conditioner 1, a classification model 430B is generated by a nonlinear algorithm using operating state quantities during heating operation related to determining whether or not there is a refrigerant leak in the refrigerant circuit 6, such as the rotation speed of the compressor 11, the outside air temperature, and the degree of subcooling and superheat during heating operation. As a result, a classification model 430B can be generated that can determine whether or not there is a leak of refrigerant circulating in the refrigerant circuit 6 during heating operation, without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0087] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the classification model 430B for heating operation, the current rotation speed of the compressor 11 during heating operation, the outside air temperature, and the degree of subcooling and superheat during heating operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0088] In the multiple regression analysis process, the current operating state quantities (sensor values) after the data filtering process and the data cleansing process are substituted into the classification model 430. In this embodiment, the classification model 430 is generated using feature quantities obtained by simulation, and the feature quantities obtained by simulation do not include abnormal values ​​or values ​​that are significantly larger or smaller than others. By performing the data filtering process and the data cleansing process to substitute the operating state quantities from which abnormal values ​​and abnormal values ​​have been removed into the classification model of the classification model 430 generated using such feature quantities that do not include abnormal values ​​or abnormal values, it is possible to more accurately determine the presence or absence of a refrigerant leak.

[0089] In the first embodiment, the classification model 430 used in the first control unit 20 is generated using the rotation speed, the degree of subcooling, and the degree of superheating of the compressor 11 in addition to the outside air temperature. However, the classification model 430 (430A, 430B) may be generated using at least two of the three operation state quantities, namely the rotation speed, the degree of subcooling, and the degree of superheating of the compressor 11, and the outside air temperature, and can be modified as appropriate.

[0090] In the air conditioner 1 of Example 1, a classification model 430 for cooling operation and heating operation is generated using a total of four operating state quantities: outdoor air temperature and three operating state quantities (the rotation speed of the compressor 11, the degree of subcooling, and the degree of superheating). As another example, the classification model 430 for cooling operation and heating operation may be generated using a total of three operating state quantities: outdoor air temperature and two operating state quantities (for example, at least two of the rotation speed of the compressor 11, the degree of subcooling, and the degree of superheating). As in this example and other examples, by reducing the number of operating state quantities used to determine the presence or absence of a refrigerant leak (for example, by reducing the number to four or less), it becomes possible to determine the presence or absence of a leak without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature. It is known that a smaller number of features makes overlearning less likely to occur, but this may result in a decrease in the accuracy of the classification model. Therefore, as a method for improving the accuracy of the classification model while avoiding overlearning, three of the four types of operating state quantities are combined to generate multiple (three types) classification models, and the majority of the judgment results from each classification model is used (a majority vote is taken on the judgment results) to determine whether or not there is a refrigerant leak. An embodiment will be described below as Example 2. Note that the same components as those in the air conditioner 1 of Example 1 are given the same reference numerals, and descriptions of the overlapping components and operations will be omitted.

[0091] Fig. 7 is a block diagram showing an example of a first control unit 20A of Example 2. The air conditioner 1 of Example 2 differs from the air conditioner 1 of Example 1 in that a first classification model 431, a second classification model 432, and a third classification model 433 are used instead of the classification model 430 during cooling operation and heating operation. In Fig. 7, the first classification model 431, the second classification model 432, and the third classification model 433 are stored in a first storage unit 43A in the first control unit 20A.

[0092] <Configuration of Classification Model> FIG. 8 is an explanatory diagram showing an example of feature quantities for each classification model type. The first classification model 431 is a learning model generated using the rotation speed of the compressor 11, the outdoor air temperature, and the degree of subcooling, which are among the operating state quantities, and a leak / normal label. The first classification model 431 includes a first classification model 431A used during cooling operation and a first classification model 431B used during heating operation. The first classification model 431A used during cooling operation is generated using the rotation speed of the compressor 11, the outdoor air temperature, the degree of subcooling during cooling operation (high-pressure saturation temperature - outdoor heat exchanger outlet temperature), and a leak / normal label. The first classification model 431B used during heating operation is generated using the rotation speed of the compressor 11, the outdoor air temperature, the degree of subcooling during heating operation (high-pressure saturation temperature - indoor heat exchanger outlet temperature), and the presence or absence of refrigerant leakage.

[0093] The second classification model 432 is a learning model generated using the rotation speed, outside air temperature, and degree of superheat of the compressor 11, and the presence or absence of refrigerant leakage, which are among the operating state quantities. The second classification model 432 has a second classification model 432A used during cooling operation and a second classification model 432B used during heating operation. The second classification model 432A used during cooling operation is generated using the rotation speed, outside air temperature, and degree of superheat of the compressor 11, and the presence or absence of refrigerant leakage. The second classification model 432B used during heating operation is generated using the rotation speed, outside air temperature, and degree of superheat of the compressor 11, and a leakage / normal label.

[0094] The third classification model 433 is a learning model generated using the outdoor air temperature, the degree of subcooling, and the degree of superheat among the operating state quantities. The third classification model 433 has a third classification model 433A used during cooling operation and a third classification model 433B used during heating operation. The third classification model 433A used during cooling operation is generated using the outdoor air temperature, the degree of subcooling (high-pressure saturation temperature - outdoor heat exchanger outlet temperature) and the degree of superheat during cooling operation, and a leak / normal label. The third classification model 433B used during heating operation is generated using the outdoor air temperature, the degree of subcooling (high-pressure saturation temperature - indoor heat exchanger outlet temperature) and the degree of superheat during heating operation, and the presence or absence of refrigerant leakage.

[0095] <Operation of Estimation Processing> Figure 9 is a flowchart showing an example of the processing operation of the first control unit 20A related to the estimation processing of Example 2. It is assumed that the first control unit 20A holds a first classification model 431, a second classification model 432, and a third classification model 433 that have been generated in advance. In Figure 9, the first control unit 44 in the first control unit 20A collects driving state quantities as driving data via the first acquisition unit 42 (step S31). The first control unit 44 executes a data filtering process to extract any driving state quantity from the collected driving data (step S32). The first control unit 44 executes a data cleansing process (step S33).

[0096] The data filtering process does not use all of the multiple operating state quantities, but extracts only a portion of the multiple operating state quantities necessary to determine the presence or absence of a refrigerant leak based on predetermined filter conditions. By substituting the operating state quantities that have been subjected to the data filtering process (with abnormal values ​​and outliers removed) into the generated classification model, the presence or absence of a refrigerant leak can be determined more accurately.

[0097] The data cleansing process is a process for excluding operation state variables that may lead to an erroneous determination, rather than using all of the acquired operation state variables to determine whether or not there is a refrigerant leak.

[0098] Furthermore, as a data cleansing process, the first control unit 44 extracts the current rotation speed of the compressor 11, the current outdoor air temperature, the current degree of subcooling, and the current degree of superheat, and then calculates the theoretical discharge temperature of the compressor 11 based on the high-pressure saturation temperature of the outdoor heat exchanger 13, the low-pressure saturation temperature of the outdoor heat exchanger 13, and the suction temperature of the compressor 11. The first control unit 44 compares the calculated theoretical discharge temperature with the actual discharge temperature. The first control unit 44 then deletes from the extracted data the current rotation speed of the compressor 11, the current outdoor air temperature, the current degree of subcooling, and the current degree of superheat extracted when the theoretical discharge temperature exceeds the actual discharge temperature. The first control unit 44 then substitutes the current rotation speed of the compressor 11, the current outdoor air temperature, the degree of subcooling, and the current degree of superheat extracted when the theoretical discharge temperature is equal to or lower than the actual discharge temperature into the first classification model 431, the second classification model 432, and the third classification model 433.

[0099] 9 , the first control unit 44 extracts the rotation speed, outdoor air temperature, degree of subcooling, and degree of superheating of the compressor 11 from the operating data after the cleansing process (step S34). The first control unit 44 then assigns the operating data of the rotation speed, outdoor air temperature, and degree of subcooling of the compressor 11 extracted in step S34 to the first classification model of the first classification model 431 (step S35A). For example, during cooling operation, the first control unit 44 assigns the operating data of the rotation speed, outdoor air temperature, and degree of subcooling during cooling operation to the classification model of the first classification model 431 used during cooling operation. Furthermore, during heating operation, the first control unit 44 assigns the operating data of the rotation speed, outdoor air temperature, and degree of subcooling during heating operation to the classification model of the first classification model 431 used during heating operation.

[0100] The first control unit 44 obtains a determination result of the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the first classification model after the operational data substitution (step S36A). That is, the first control unit 44 determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during cooling operation using the first classification model of the first classification model 431A used during cooling operation. The first control unit 44 determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during heating operation using the first classification model of the first classification model 431B used during heating operation. The first control unit 44 outputs the determination result of the first classification model 431 (step S37A) and executes the majority vote process of step S38 described later.

[0101] After step S34, the first control unit 44 substitutes the extracted operating data of the rotation speed, the outside air temperature, and the degree of superheat into the second classification model of the second classification model 432 (step S35B). For example, during cooling operation, the first control unit 44 substitutes the operating data of the rotation speed, the outside air temperature, and the degree of superheat into the second classification model of the second classification model 432A used during cooling operation. During heating operation, the first control unit 44 substitutes the operating data of the rotation speed, the outside air temperature, and the degree of superheat into the second classification model of the second classification model 432B used during heating operation.

[0102] The first control unit 44 obtains a determination result of the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the second classification model after the operating data substitution (step S36B). That is, the first control unit 44 determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during cooling operation using the second classification model 432A used during cooling operation. The first control unit 44 also determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during heating operation using the second classification model 432B used during heating operation. The first control unit 44 outputs the determination result of the second classification model 432 (step S37B) and executes the majority vote process of step S38, which will be described later.

[0103] After step S34, the first control unit 44 substitutes the extracted operating data of the outside air temperature, the degree of subcooling, and the degree of superheating into the third classification model of the third classification model 433 (step S35C). For example, during cooling operation, the first control unit 44 substitutes the operating data of the outside air temperature, the degree of subcooling during cooling operation, and the degree of superheating into the third classification model 433A used during cooling operation. During heating operation, the first control unit 44 substitutes the operating data of the outside air temperature, the degree of subcooling during heating operation, and the degree of superheating into the third classification model 433B used during heating operation.

[0104] The first control unit 44 obtains a determination result of the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the third classification model after the operation data has been substituted (step S36C). That is, the first control unit 44 determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during cooling operation using the third classification model 433A used during cooling operation. The first control unit 44 also determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during heating operation using the third classification model 433B used during heating operation. The first control unit 44 outputs the determination result of the third classification model 433 (step S37C) and executes the majority vote process of step S38, which will be described later.

[0105] The first control unit 44 executes a majority voting process (step S38) to determine the refrigerant leak determination result by majority vote, based on the determination results of the first classification model 431, the second classification model 432, and the third classification model 433. The majority voting process tallies the number of determination results indicating the presence of a refrigerant leak and the number of determination results indicating no refrigerant leak, based on the determination results of the first classification model 431, the second classification model 432, and the third classification model 433. The majority voting process then compares the number of determination results indicating the presence of a refrigerant leak with the number of determination results indicating no refrigerant leak, and determines the majority vote for the determination results.

[0106] The first control unit 44 determines whether the majority result indicates that a refrigerant leak exists (step S39). If the majority result indicates that a refrigerant leak exists (step S39: Yes), the first control unit 44 outputs a notification that a refrigerant leak exists (step S40) and ends the processing operation shown in FIG.

[0107] Furthermore, if the majority decision result indicates that there is not a refrigerant leak (step S39: No), the first control unit 44 outputs a notification that there is no refrigerant leak (step S41) and ends the processing operation shown in FIG.

[0108] <Effects of Example 2> In the air conditioner 1 of Example 2, a first classification model 431 is generated using the rotation speed, outdoor air temperature, and degree of supercooling of the compressor 11, a second classification model 432 is generated using the rotation speed, outdoor air temperature, and degree of superheating of the compressor 11, and a third classification model 433 is generated using the outdoor air temperature, degree of subcooling, and degree of superheating. As a result, overlearning can be avoided by combining three of the four types of operation state quantities to generate each of the three types of classification models.

[0109] The air conditioner 1 takes a majority vote on the presence or absence of a refrigerant leak using the judgment results of the first classification model 431, the judgment results of the second classification model 432, and the judgment results of the third classification model 433. The air conditioner 1 then determines the presence or absence of a refrigerant leak based on the result of the majority vote. As a result, the presence or absence of a refrigerant leak can be determined with higher accuracy when using the majority vote of the judgment results compared to when the classification model 430 of the first embodiment is used.

[0110] In the air conditioner 1, a first classification model 431A to be used during cooling operation is generated by a nonlinear algorithm using operating state quantities during cooling operation related to determining the presence or absence of refrigerant leakage, such as the rotation speed of the compressor 11, the outside air temperature, and the degree of subcooling during cooling operation, as well as the presence or absence of refrigerant leakage. As a result, it is possible to generate a first classification model 431A that can determine the presence or absence of refrigerant leakage circulating within the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0111] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the first classification model 431A used during cooling operation, the current rotation speed of the compressor 11 during cooling operation, the outside air temperature, and the degree of subcooling during cooling operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0112] In the air conditioner 1, a first classification model 431B to be used during heating operation is generated by a nonlinear algorithm using operating state quantities during heating operation related to determining whether or not there is a refrigerant leak, such as the rotation speed of the compressor 11, the outside air temperature, and the degree of subcooling during heating operation, as well as the presence or absence of a refrigerant leak. As a result, it is possible to generate a first classification model 431B that can determine whether or not there is a leak of the refrigerant circulating in the refrigerant circuit 6 during heating operation, without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0113] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the first classification model 431B used during heating operation, the current rotation speed of the compressor 11 during heating operation, the outside air temperature, and the degree of subcooling during heating operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0114] In the air conditioner 1, a second classification model 432A to be used during cooling operation is generated by a nonlinear algorithm using operating state quantities during cooling operation related to determining the presence or absence of refrigerant leakage in the refrigerant circuit 6, such as the rotation speed, outside air temperature, and degree of superheat of the compressor 11. As a result, it is possible to generate a second classification model 432A that can determine the presence or absence of refrigerant leakage circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0115] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the second classification model 432A used during cooling operation and the current rotation speed, outside air temperature, and degree of superheat of the compressor 11 during cooling operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0116] In the air conditioner 1, a second classification model 432B to be used during heating operation is generated by a nonlinear algorithm using operating state quantities during heating operation related to determining whether or not there is a refrigerant leak in the refrigerant circuit 6, such as the rotation speed, outside air temperature, and degree of superheat of the compressor 11, and the presence or absence of a refrigerant leak. As a result, it is possible to generate a second classification model 432B that can determine whether or not there is a leak of the refrigerant circulating in the refrigerant circuit 6 during heating operation, without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0117] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the second classification model 432B used during heating operation and the current rotation speed, outside air temperature, and degree of superheat of the compressor 11 during heating operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0118] In the air conditioner 1, a third classification model 433A to be used during cooling operation is generated by a nonlinear algorithm using operating state quantities during cooling operation related to the determination of the presence or absence of refrigerant leakage, such as the outside air temperature, the degree of subcooling and superheat during cooling operation, and the presence or absence of refrigerant leakage. As a result, it is possible to generate a third classification model 433A that can determine the presence or absence of leakage of refrigerant circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0119] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the third classification model 433A used during cooling operation, the current outside air temperature during cooling operation, and the degree of subcooling and superheat during cooling operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0120] In the air conditioner 1, a third classification model 433B to be used during heating operation is generated by a nonlinear algorithm using operating state quantities during heating operation related to the determination of the presence or absence of refrigerant leakage, such as the outside air temperature, the degree of subcooling and superheat during heating operation, and the presence or absence of refrigerant leakage. As a result, it is possible to generate a third classification model 433B that can determine the presence or absence of leakage of refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0121] The air conditioner 1 estimates the presence or absence of a refrigerant leak using the third classification model 433B used during heating operation, the current outside air temperature during heating operation, and the degree of subcooling and superheat during heating operation. As a result, it is possible to determine the current presence or absence of a leak of the refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0122] In the air conditioners 1 of Examples 1 and 2, a refrigerant circuit employing an SC heat exchanger is illustrated, but the present invention is also applicable to a refrigerant circuit not employing an SC heat exchanger, and therefore, this embodiment will be described as Example 3. Note that the same components as those in the air conditioner 1 of Example 1 are given the same reference numerals, and descriptions of the overlapping components and operations will be omitted.

[0123] 10 is an explanatory diagram showing an example of an outdoor unit 2 and an indoor unit 3 of Example 3. The air conditioner 1A of Example 3 differs from the air conditioner 1 of Example 1 in that it has a refrigerant circuit 6A that does not include an injection circuit 19 including an SC heat exchanger 19C and the like.

[0124] The outdoor unit 2 has a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an outdoor unit expansion valve 14, a first shut-off valve 15, a second shut-off valve 16, an accumulator 17, an outdoor unit fan 18, and a first control unit 20. The compressor 11, the four-way valve 12, the outdoor heat exchanger 13, the outdoor unit expansion valve 14, the first shut-off valve 15, the second shut-off valve 16, and the accumulator 17 are connected to each other by refrigerant pipes described in detail below to form an outdoor-side refrigerant circuit that forms part of the refrigerant circuit 6A.

[0125] <Operation of Refrigerant Circuit> Next, the flow of refrigerant in the refrigerant circuit 6A and the operation of each part during air conditioning operation of the air conditioner 1A in this embodiment will be described. Note that the arrows in Fig. 10 indicate the flow of refrigerant during heating operation.

[0126] When the air conditioner 1A performs heating operation, the four-way valve 12 is switched so that the first port 12A and the fourth port 12D are connected and the second port 12B and the third port 12C are connected. As a result, the refrigerant circuit 6A becomes a heating cycle in which each indoor heat exchanger 51 functions as a condenser and the outdoor heat exchanger 13 functions as an evaporator. For ease of explanation, the flow of refrigerant during heating operation is indicated by solid arrows in Figure 10.

[0127] When the compressor 11 is driven with the refrigerant circuit 6A in the above state, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 and into the four-way valve 12, then flows from the four-way valve 12 through the outdoor gas pipe 24 and into the gas pipe 5 via the second shut-off valve 16. The refrigerant flowing through the gas pipe 5 is diverted to each indoor unit 3 via each gas pipe connection 54. The refrigerant that flows into each indoor unit 3 flows through each indoor gas pipe 57 and into each indoor heat exchanger 51. The refrigerant that flows into each indoor heat exchanger 51 condenses by exchanging heat with indoor air drawn into each indoor unit 3 by the rotation of each indoor unit fan 55. In other words, each indoor heat exchanger 51 functions as a condenser, and the indoor air heated by the refrigerant in each indoor heat exchanger 51 is blown into the room through an air outlet (not shown), thereby heating the room in which each indoor unit 3 is installed.

[0128] The refrigerant that flows from each indoor heat exchanger 51 into each indoor liquid pipe 56 is decompressed by passing through each indoor unit expansion valve 52, the opening of which is adjusted so that the degree of refrigerant subcooling at the refrigerant outlet side of each indoor heat exchanger 51 becomes the target degree of refrigerant subcooling. Here, the target degree of refrigerant subcooling is determined based on the cooling capacity required by each indoor unit 3.

[0129] The refrigerant decompressed by each indoor unit expansion valve 52 flows from each indoor liquid pipe 56 through each liquid pipe connection 53 into the liquid pipe 4. The refrigerant that joins in the liquid pipe 4 flows into the outdoor unit 2 through the first shut-off valve 15. The refrigerant that flows into the first shut-off valve 15 of the outdoor unit 2 flows through the outdoor liquid pipe 25 and is decompressed while passing through the outdoor unit expansion valve 14. The refrigerant that is decompressed by the outdoor unit expansion valve 14 flows through the outdoor liquid pipe 25 into the outdoor heat exchanger 13, and evaporates through heat exchange with outside air that flows in from an intake port (not shown) of the outdoor unit 2 due to the rotation of the outdoor unit fan 18. The refrigerant that flows out from the outdoor heat exchanger 13 to the outdoor refrigerant pipe 26 flows in this order: the four-way valve 12, the outdoor refrigerant pipe 26, the accumulator 17, and the suction pipe 22. The refrigerant is then drawn into the compressor 11 and compressed again, and flows out into the outdoor gas pipe 24 via the first port 12A and the fourth port 12D of the four-way valve 12.

[0130] Furthermore, when the air conditioner 1A is operating in cooling mode, the four-way valve 12 is switched so that the first port 12A and the second port 12B are connected, and the third port 12C and the fourth port 12D are connected. As a result, the refrigerant circuit 6A becomes a cooling cycle in which each indoor heat exchanger 51 functions as an evaporator and the outdoor heat exchanger 13 functions as a condenser. For ease of explanation, the flow of refrigerant during cooling mode is indicated by dashed arrows in Figure 10.

[0131] When the compressor 11 is driven in the refrigerant circuit 6A state, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 and into the four-way valve 12, and then flows from the four-way valve 12 through the outdoor refrigerant pipe 26 and into the outdoor heat exchanger 13. The refrigerant that has flowed into the outdoor heat exchanger 13 condenses by exchanging heat with outdoor air that has been drawn into the outdoor unit 2 by the rotation of the outdoor unit fan 18. In other words, the outdoor heat exchanger 13 functions as a condenser, and the indoor air heated by the refrigerant in the outdoor heat exchanger 13 is blown outside through an air outlet (not shown).

[0132] The refrigerant that flows from the outdoor heat exchanger 13 into the outdoor liquid pipe 25 passes through the outdoor unit expansion valve 14, which is fully open, and is decompressed. The refrigerant decompressed by the outdoor unit expansion valve 14 flows through the liquid pipe 4 via the first stop valve 15 and is diverted to each indoor unit 3. The refrigerant that flows into each indoor unit 3 flows through each liquid pipe connection 53, into the indoor liquid pipe 56, and is decompressed by passing through the indoor unit expansion valve 52, which has an opening adjusted to such an extent that the refrigerant subcooling degree becomes the target refrigerant subcooling degree at the refrigerant outlet of the indoor heat exchanger 51. The refrigerant decompressed by the indoor unit expansion valve 52 flows through the indoor liquid pipe 56 and flows into the indoor heat exchanger 51, where it exchanges heat with indoor air that flows in from an intake port (not shown) of the indoor unit 3 due to the rotation of the indoor unit fan 55, and evaporates. In other words, each indoor heat exchanger 51 functions as an evaporator, and the indoor air cooled by the refrigerant in each indoor heat exchanger 51 is blown into the room from an air outlet (not shown), thereby cooling the room in which each indoor unit 3 is installed.

[0133] The refrigerant flowing from the indoor heat exchanger 51 to the gas pipe 5 via the gas pipe connection part 54 flows through the second shut-off valve 16 of the outdoor unit 2 to the outdoor gas pipe 24 and flows into the fourth port 12D of the four-way valve 12. The refrigerant that has flowed into the fourth port 12D of the four-way valve 12 flows from the third port 12C into the refrigerant inlet side of the accumulator 17. The refrigerant that has flowed into the refrigerant inlet side of the accumulator 17 flows through the suction pipe 22 and is sucked into the compressor 11 to be compressed again.

[0134] During cooling operation of the air conditioner 1A, the outdoor heat exchanger 13 functions as a condenser, and the indoor heat exchanger 51 functions as an evaporator. During heating operation of the air conditioner 1A, the outdoor heat exchanger 13 functions as an evaporator, and the indoor heat exchanger 51 functions as a condenser.

[0135] The classification model 430 is generated using, for example, at least two of the three operation state quantities, i.e., the rotation speed, the degree of subcooling, and the degree of superheating of the compressor 11, the outside air temperature, and the presence or absence of refrigerant leakage. The classification models 430 are a classification model 430A used during cooling operation and a classification model 430B used during heating operation, which determine the presence or absence of refrigerant leakage in the refrigerant circuit 6A.

[0136] The first control unit 44 then extracts the rotation speed, outside air temperature, degree of subcooling, and degree of superheating of the compressor 11 from the operating data after the cleansing process. The first control unit 44 assigns the extracted operating data of the rotation speed, outside air temperature, degree of subcooling, and degree of superheating of the compressor 11 to the classification model 430. For example, during cooling operation, the first control unit 44 assigns the operating data of the rotation speed, outside air temperature, degree of subcooling, and degree of superheating of the compressor 11 to the classification model 430A used during cooling operation. Furthermore, during heating operation, the first control unit 44 assigns the operating data of the rotation speed, outside air temperature, degree of subcooling, and degree of superheating of the compressor 11 to the classification model 430B used during heating operation.

[0137] The first control unit 44 obtains a determination result of whether or not there is a refrigerant leak in the refrigerant circuit 6 using the classification model after substituting the operating data. That is, the first control unit 44 determines whether or not there is a refrigerant leak in the refrigerant circuit 6 during cooling operation using the classification model 430A used during cooling operation. The first control unit 44 also determines whether or not there is a refrigerant leak in the refrigerant circuit 6 during heating operation using the classification model 430B used during heating operation. The first control unit 44 determines whether or not there is a refrigerant leak as a result of the determination. If the determination result indicates there is a refrigerant leak, the first control unit 44 outputs a notification that there is a refrigerant leak. If the determination result indicates there is no refrigerant leak, the first control unit 44 outputs a notification that there is no refrigerant leak.

[0138] Effect of Third Embodiment In the air conditioner 1A of the third embodiment, a classification model 430 is generated by a nonlinear algorithm using the operating state quantities related to determining whether or not there is a refrigerant leakage in the refrigerant circuit 6A, the rotation speed of the compressor 11, the outside air temperature, the degree of subcooling, and the degree of superheat. As a result, it is possible to generate a classification model 430 that can determine whether or not there is a refrigerant leakage in the refrigerant circuit 6A that does not include the injection circuit 19 including the SC heat exchanger 19C, etc., without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0139] The air conditioner 1A estimates the presence or absence of refrigerant leakage using the classification model 430 and the current rotation speed, outside air temperature, degree of subcooling, and degree of superheat of the compressor 11. As a result, the current presence or absence of refrigerant leakage in the refrigerant circuit 6A can be determined without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0140] Furthermore, in the air conditioner 1A of Example 3, an example is given of using classification model 430, but it is also possible to use a first classification model 431, a second classification model 432, and a third classification model 433, as in the air conditioner 1 of Example 2.

[0141] In the air conditioner 1A, a first classification model 431 is generated using the rotation speed, outdoor air temperature, and degree of supercooling of the compressor 11, a second classification model 432 is generated using the rotation speed, outdoor air temperature, and degree of superheating of the compressor 11, and a third classification model 433 is generated using the outdoor air temperature, degree of supercooling, and degree of superheating. As a result, overlearning can be avoided by combining three of the four types of operation state quantities to generate each of the three types of classification models.

[0142] In the air conditioner 1A, a majority vote is taken as to whether or not a refrigerant leak exists using the judgment results of the first classification model 431, the judgment results of the second classification model 432, and the judgment results of the third classification model 433, and the presence or absence of a refrigerant leak is determined based on the result of the majority vote. As a result, the presence or absence of a refrigerant leak can be determined with higher accuracy when the majority vote of the judgment results is used compared to when classification model 430 is used.

[0143] In this embodiment, a case has been illustrated in which simulation results for each operating state quantity are obtained during the design stage of the air conditioner 1, and the first control unit 44 in the outdoor unit 2, which has a learning function, learns the simulation results, and the resulting classification model 430 is stored in the first storage unit 43. However, this is not limited to this. For example, as shown in the modified example of Example 1, there may be a server connected to the air conditioner 1 via a communication network, and this server may execute a generation process to generate the classification model 430 and transmit the generated classification model 430 to the first control unit 20. The first control unit 44 in the first control unit 20 may then store the classification model 430 received from the server in the first storage unit 43. The embodiment may be modified as appropriate.

[0144] The air conditioners 1 (1A) of Examples 1 to 3 illustrate classification models 430 that determine whether or not there is a refrigerant leak when N indoor units 3 are connected to one outdoor unit 2. However, the same method as in Examples 1 to 3 can also be used to determine whether or not there is a refrigerant leak in an air conditioner 1 in which one outdoor unit 2 and one indoor unit 3 are connected.

[0145] Furthermore, the components of each unit shown in the figure do not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each unit is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0146] Furthermore, the various processing functions performed by each device may be executed in whole or in part on a CPU (Central Processing Unit) (or a microcomputer such as an MPU (Micro Processing Unit) or an MCU (Micro Controller Unit)). Needless to say, the various processing functions may be executed in whole or in part on a program analyzed and executed by the CPU (or a microcomputer such as an MPU or MCU), or on hardware using wired logic.

[0147] The various processes described in this embodiment can be realized by executing a prepared refrigerant leakage determination program, for example, in the first control unit 20 or an information processing device connected to the air conditioner 1. By executing the refrigerant leakage determination program, the first control unit 20 or the information processing device performs a process of learning a classification model by associating the presence or absence of a refrigerant leakage with at least two state quantities out of a first state quantity indicating the state of the refrigerant in the condenser of the air conditioner 1, a second state quantity indicating the state of the refrigerant in the evaporator, and a third state quantity indicating the operating state of the air conditioner 1. As a result, it is possible to generate a classification model 430 that can determine the presence or absence of a refrigerant leakage circulating in the refrigerant circuit 6 without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0148] REFERENCE SIGNS LIST 1 Air conditioner 2 Outdoor unit 3 Indoor unit 11 Compressor 13 Outdoor heat exchanger 14 Outdoor unit expansion valve 20 First control unit 430 Classification model 431 First classification model 432 Second classification model 433 Third classification model 44 First control unit 51 Indoor heat exchanger

Claims

1. A refrigerant leakage detection device for detecting refrigerant leakage in an air conditioner having an outdoor unit with a compressor, an outdoor heat exchanger, and an expansion valve, and an indoor unit with an indoor heat exchanger, the outdoor unit and the indoor unit being connected by refrigerant piping to form a refrigerant circuit through which refrigerant circulates, the refrigerant leakage detection device being characterized by having a control unit equipped with a classification model that learns by associating at least two state quantities with the presence or absence of refrigerant leakage, out of a first state quantity that indicates the state of refrigerant in the condenser of the air conditioner, a second state quantity that indicates the state of refrigerant in the evaporator, and a third state quantity that indicates the operating state of the air conditioner.

2. The refrigerant leakage determination device according to claim 1, characterized in that the control unit determines whether or not there is a refrigerant leakage in the refrigerant circuit using a plurality of different classification models.

3. The refrigerant leakage determination device described in claim 2, characterized in that the control unit has a first classification model, a second classification model, and a third classification model as the different classification models, and determines whether or not there is a refrigerant leakage in the refrigerant circuit using the majority of the determination results of each classification model.

4. The refrigerant leakage detection device according to claim 3, wherein the third state quantity is the rotation speed of the compressor, the second state quantity is the degree of subcooling, and the first state quantity is the degree of superheating.

5. The refrigerant leakage detection device described in claim 4, characterized in that the control unit calculates the degree of subcooling based on the heat exchange outlet temperature of the condenser and the high-pressure saturation temperature of the condenser when the outdoor heat exchanger functions as a condenser, and calculates the degree of superheat based on the suction temperature of the compressor and the low-pressure saturation temperature of the compressor when the outdoor heat exchanger functions as an evaporator.

6. The refrigerant leakage detection device according to claim 5, further comprising a detection unit that detects the actual discharge temperature of the refrigerant discharged from the compressor, wherein the control unit, after acquiring the current compressor rotation speed, current outside air temperature, current degree of subcooling, and current degree of superheat, calculates a theoretical discharge temperature of the compressor based on the high-pressure saturation temperature of the outdoor heat exchanger, the low-pressure saturation temperature of the outdoor heat exchanger, and the suction temperature of the compressor, compares the theoretical discharge temperature with the actual discharge temperature detected by the detection unit, deletes the current compressor rotation speed, current outside air temperature, current degree of subcooling, and current degree of superheat extracted when the theoretical discharge temperature exceeds the actual discharge temperature, and substitutes the current compressor rotation speed, current outside air temperature, current degree of subcooling, and current degree of superheat extracted when the theoretical discharge temperature is equal to or lower than the actual discharge temperature into the first classification model, the second classification model, and the third classification model.

7. An air conditioner having an outdoor unit having a compressor, an outdoor heat exchanger, and an expansion valve, and an indoor unit having an indoor heat exchanger, and a refrigerant circuit formed by connecting the outdoor unit and the indoor unit with refrigerant piping, and equipped with a refrigerant leakage detection device that detects refrigerant leakage in the air conditioner in which refrigerant circulates within the refrigerant circuit, wherein the refrigerant leakage detection device has a control unit equipped with a classification model that learns by associating at least two state quantities out of a first state quantity that indicates the state of refrigerant in the condenser of the air conditioner, a second state quantity that indicates the state of refrigerant in the evaporator, and a third state quantity that indicates the operating state of the air conditioner, with the presence or absence of refrigerant leakage.

8. An air conditioner according to claim 7, characterized in that the refrigerant circuit is equipped with a subcooling heat exchanger disposed between the outdoor heat exchanger and the indoor heat exchanger.

9. A refrigerant leakage detection program that causes a refrigerant leakage detection device that detects refrigerant leakage in an air conditioner having an outdoor unit with a compressor, an outdoor heat exchanger, and an expansion valve, and an indoor unit with an indoor heat exchanger, with a refrigerant circuit formed by connecting the outdoor unit and the indoor unit with refrigerant piping, and in which refrigerant circulates within the refrigerant circuit, to execute a process of learning a classification model by associating at least two state quantities out of a first state quantity that indicates the state of refrigerant in the condenser of the air conditioner, a second state quantity that indicates the state of refrigerant in the evaporator, and a third state quantity that indicates the operating state of the air conditioner, with the presence or absence of refrigerant leakage.

10. A refrigerant leakage detection device for detecting refrigerant leakage in an air conditioner having an outdoor unit with a compressor, an outdoor heat exchanger, and an expansion valve, and an indoor unit with an indoor heat exchanger, the outdoor unit and the indoor unit being connected by refrigerant piping to form a refrigerant circuit through which refrigerant circulates, the refrigerant leakage detection device executing a process for learning a classification model by associating at least two state quantities out of a first state quantity indicating the state of refrigerant in the condenser of the air conditioner, a second state quantity indicating the state of refrigerant in the evaporator, and a third state quantity indicating the operating state of the air conditioner with the presence or absence of refrigerant leakage.

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