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

Abstract

To provide a refrigerant leakage determination device, etc. capable of determining whether or not there is a leakage of a refrigerant circulating a refrigerant circuit to outside, regardless of a type of an air conditioner.SOLUTION: A refrigerant leakage determination device determines leakage of a refrigerant in an air conditioner that has a refrigerant circuit having an outdoor unit with a compressor, an outdoor heat exchanger and an expansion valve and an indoor unit with an indoor heat exchanger and formed by connecting the outdoor unit and the indoor unit by using refrigerant piping and in which a refrigerant circulates in the refrigerant circuit. The refrigerant leakage determination device includes a control section having a classification model learned by associating at least two state amounts out of a first state amount indicating a state of the refrigerant in a condenser of the air conditioner, a second state amount indicating the state of the refrigerant in an evaporator and a third state amount indicating a state of an operation of the air conditioner and presence / absence of leakage of the refrigerant with each other.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] For example, a refrigerant amount estimation device has been proposed that estimates the amount of refrigerant circulating in a refrigerant circuit using the operating state variables that can be detected in the refrigerant circuit. In the refrigerant amount estimation device of Patent Document 1, among the plurality of operating state variables that can be detected in the refrigerant circuit of an air conditioner equipped with a subcooling heat exchanger, the opening degree of the SC expansion valve and the SC heat exchange outlet temperature are learned in association with the refrigerant amount. Then, in the air conditioner, the refrigerant amount estimation device is used to estimate the amount of refrigerant circulating in the refrigerant circuit during operation using the opening degree of the SC expansion valve and the SC heat exchange outlet temperature during operation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the case of an air conditioner not equipped with a subcooling heat exchanger, the opening degree of the SC expansion valve and the SC heat exchange outlet temperature cannot be obtained. Therefore, in addition to the estimation model for an air conditioner equipped with a subcooling heat exchanger, it is necessary to prepare a refrigerant amount estimation device for an air conditioner not equipped with a subcooling heat exchanger, respectively.

[0005] On the other hand, the purpose of estimating the amount of refrigerant 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, even before estimating the amount of refrigerant. This is because if the refrigerant sealed in the air conditioner leaks to the outside, the cooling and heating capacity of the air conditioner (the amount of heat energy removed from or added to the room per unit time) will decrease.

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

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

[0008] One embodiment of a refrigerant leak 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 connected by refrigerant piping to form a refrigerant circuit. The refrigerant leak detection device determines refrigerant leakage in an air conditioner in which refrigerant circulates within the refrigerant circuit. The refrigerant leak detection device has a control unit equipped with a classification model that learns by associating at least two of the following state quantities: 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, with the presence or absence of refrigerant leakage. [Effects of the Invention]

[0009] One aspect of this is that, regardless of the type of air conditioner, it can determine whether or not the refrigerant circulating within the refrigerant circuit is leaking to the outside. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an explanatory diagram showing an example of an air conditioner in this embodiment. [Figure 2] Figure 2 is an explanatory diagram showing an example of the outdoor and indoor units of Example 1. [Figure 3] Figure 3 is a block diagram showing an example of the first control unit of Example 1. [Figure 4] Figure 4 is a block diagram showing an example of the second control unit of Example 1. [Figure 5A] Figure 5A is an explanatory diagram showing an example of a modified air conditioning system. [Figure 5B] Figure 5B is a block diagram showing an example of a third control unit in a modified form. [Figure 6] Figure 6 is a flowchart showing an example of the processing operation of the first control unit involved in the estimation process of Example 1. [Figure 7] Figure 7 is a block diagram showing an example of the first control unit of Example 2. [Figure 8] Figure 8 is an explanatory diagram showing an example of features for each classification model type. [Figure 9] Figure 9 is a flowchart showing an example of the processing operation of the first control unit involved in the estimation process of Example 2. [Figure 10] Figure 10 is an explanatory diagram showing an example of the outdoor and indoor units of Example 3. [Modes for carrying out the invention]

[0011] The following describes in detail embodiments of the refrigerant leak detection device and the like disclosed in this application, based on the drawings. However, these embodiments do not limit the disclosed technology. Furthermore, each embodiment shown below may be modified as appropriate, provided that it does not create inconsistencies. [Examples]

[0012] <Air Conditioner Configuration> FIG. 1 is an explanatory diagram showing an example of the air conditioner 1 of the present embodiment. The air conditioner 1 shown in FIG. 1 includes 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 a liquid pipe 4 and a gas pipe 5. Then, the outdoor unit 2 and the indoor unit 3 are connected by a refrigerant pipe such as the liquid pipe 4 and the gas pipe 5, thereby forming the refrigerant circuit 6 of the air conditioner 1.

[0013] <Configuration of Outdoor Unit> FIG. 2 is an explanatory diagram showing an example of the outdoor unit 2 and the indoor unit 3 of Embodiment 1. The outdoor unit 2 includes 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. Using 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, an outdoor-side refrigerant circuit that is mutually connected by each refrigerant pipe and forms a part of the refrigerant circuit 6 is formed.

[0014] The compressor 11 is, for example, a high-pressure container type capacity variable compressor whose operating capacity can be varied according to the drive of a motor (not shown) whose rotational speed is controlled by an inverter. The compressor 11 is connected between its refrigerant discharge side and the first port 12A of the four-way valve 12 by a discharge pipe 21. Further, the compressor 11 is connected between its refrigerant suction side and the refrigerant outflow side of the accumulator 17 by a suction pipe 22.

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

[0016] The outdoor heat exchanger 13 exchanges heat between the refrigerant and the outside air taken into the interior of 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 shut-off valve 15 by an outdoor liquid pipe 25. The outdoor heat exchanger 13 functions as a condenser when the air conditioner 1 performs a cooling operation, and functions as an evaporator when the air conditioner 1 performs a 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 opening degree of the outdoor unit expansion valve 14 is adjusted according to the number of pulses applied to the pulse motor, thereby adjusting the amount of refrigerant flowing into the outdoor heat exchanger 13 or the amount of refrigerant flowing out from the outdoor heat exchanger 13. The opening degree of the outdoor unit expansion valve 14 is adjusted so that the refrigerant superheat degree on the refrigerant suction side of the compressor 11 becomes the target suction refrigerant superheat degree when the air conditioner 1 is performing a heating operation. Also, the opening degree of the outdoor unit expansion valve 14 is fully opened when the air conditioner 1 is performing a cooling operation.

[0018] The accumulator 17 is connected between its refrigerant inlet side and the third port 12C of the four-way valve 12 by an outdoor refrigerant pipe 26. Further, the accumulator 17 is connected between its refrigerant outlet side and the refrigerant inlet side of the compressor 11 by a suction pipe 22. The accumulator 17 separates the refrigerant flowing into the interior of 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 formed of a resin material and is disposed in the vicinity of the outdoor heat exchanger 13. The outdoor unit fan 18 takes in outside air from a suction port not shown into the interior of the outdoor unit 2 according to the rotation of a fan motor not shown, 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 a blowout port not shown.

[0020] The injection circuit 19 includes 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 pipe 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 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 piping 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 adjusts its opening and closing and opening degree according to the control of the first control unit 20.

[0021] The SC heat exchanger 19C is installed 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 a gas-liquid two-phase refrigerant into a liquid single-phase subcooled refrigerant.

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

[0023] The SC heat exchanger 19C includes a high-pressure side flow path and a low-pressure side flow path (not shown). When the indoor unit 3 is in cooling operation, refrigerant that has flowed out from the outdoor unit expansion valve 14 flows into the high-pressure side flow path. The refrigerant that has flowed into the high-pressure side flow path exchanges heat with the refrigerant in the low-pressure side flow path and then flows out towards the first shut-off valve 15. The low-pressure side flow path is provided in the outdoor liquid pipe 25, and refrigerant that has flowed out from the SC expansion valve 19B flows into it. The refrigerant that has flowed into the low-pressure side flow path exchanges heat with the refrigerant in the high-pressure side flow path and then flows out into 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 direction of refrigerant flow when the indoor unit 3 is in heating operation. With these configurations, the downstream side of the SC heat exchanger 19C in the outdoor liquid pipe 25 becomes a flow path for liquid single-phase refrigerant. The flow path for liquid single-phase refrigerant corresponds to one section of the outdoor liquid pipe 25. When the indoor unit 3 is in cooling operation, the section between the SC heat exchanger 19C and the first shut-off valve 15 in the outdoor liquid pipe 25 is a flow path for liquid single-phase refrigerant. When the indoor unit 3 is in heating operation, the section between the SC heat exchanger 19C and the outdoor unit expansion valve 14 in the outdoor liquid pipe 25 is a flow path for liquid single-phase refrigerant.

[0025] Furthermore, the outdoor unit 2 is equipped with multiple sensors. The discharge pipe 21 is equipped with 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. Near the refrigerant inlet of the accumulator 17 of the outdoor refrigerant pipe 26, there is an intake pressure sensor 33 that detects the intake pressure, which is the pressure of the refrigerant drawn into the compressor 11, and an intake temperature sensor 34 that detects the temperature of the refrigerant drawn into the compressor 11.

[0026] A refrigerant temperature sensor 35 is located 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 outside air temperature sensor 36 is located near the intake port (not shown) of the outdoor unit 2 to detect the temperature of the outside air flowing into the inside of the outdoor unit 2, i.e., the outside air temperature.

[0027] The first control unit 20 controls the entire air conditioner 1. Figure 3 is a block diagram showing an example of the first control unit 20 of Embodiment 1. The first control unit 20 includes 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 mentioned 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 operating state quantities such as the control program of the outdoor unit 2 and detection values ​​corresponding to detection signals from various sensors, the drive status of the compressor 11 and the outdoor unit fan 18, operating information transmitted from each indoor unit 3 (for example, including 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] Furthermore, the first storage unit 43 stores a classification model 430 for determining 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 for determining 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) acquires detection values ​​from various sensors via the first communication unit 41, and receives signals containing operating 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 degree of the outdoor unit expansion valve 14 and controls the drive of the compressor 11. Furthermore, the first control unit 44 is a refrigerant leak detection device that determines whether or not there is a refrigerant leak in the refrigerant circuit 6 using the classification model 430 described above. In other words, the first control unit 44 determines whether or not there is a refrigerant leak in the air conditioner 1 in which the refrigerant circulates within the refrigerant circuit 6.

[0030] <Indoor unit configuration> As shown in Figure 2, the indoor unit 3 includes 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. These indoor heat exchanger 51, indoor unit expansion valve 52, liquid pipe connection 53, and gas pipe connection 54 are interconnected by refrigerant piping, which will be described later, to form 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 from an intake port (not shown) by the rotation of the indoor unit fan 55. The indoor heat exchanger 51 is connected to a liquid pipe connection 53 by an indoor liquid pipe 56 between one of its refrigerant inlets and outlets. The indoor heat exchanger 51 is also connected to a gas pipe connection 54 by an indoor gas pipe 57 between its other refrigerant inlet and outlet. When the air conditioner 1 is operating in heating mode, the indoor heat exchanger 51 functions as a condenser. Conversely, when the air conditioner 1 is operating in cooling mode, the indoor heat exchanger 51 functions as an evaporator.

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

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

[0034] The indoor unit 3 is equipped with various sensors. In the indoor liquid pipe 56, a liquid-side refrigerant temperature sensor 61 is positioned 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 temperature of the refrigerant flowing out of the indoor heat exchanger 51, which is the indoor heat exchanger outlet temperature. In the indoor gas pipe 57, a gas-side temperature sensor 62 is positioned to detect the temperature of the refrigerant flowing out of or into the indoor heat exchanger 51. Near the intake port (not shown) of the indoor unit 3, an intake temperature sensor 63 is positioned to detect the temperature of the indoor air flowing into the interior of the indoor unit 3, i.e., the intake temperature.

[0035] The second control unit 50 controls the entire indoor unit 3. Figure 4 is a block diagram showing an example of the second control unit 50 of Embodiment 1. The second control unit 50 includes 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, flash memory. The second storage unit 73 stores operating state quantities such as the control program of the indoor unit 3 and detected values ​​corresponding to detection signals from various sensors, the drive state of the indoor unit fan 55, operating information of the indoor unit 3 (for example, including operation / stop information, operating mode 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 the values ​​detected by various sensors in the indoor unit 3 to the first control unit 20 of the outdoor unit 2 via the second communication unit 71. Based on this input information, the second control unit 74 adjusts the opening degree of the indoor unit expansion valve 52.

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

[0038] When the air conditioner 1 is operating in heating mode, the four-way valve 12 is switched so that the first port 12A and the fourth port 12D are in communication, and the second port 12B and the third port 12C are in communication. As a result, the refrigerant circuit 6 operates in 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 the sake of explanation, the flow of refrigerant during heating operation is indicated by the solid arrows shown in Figure 2.

[0039] When the compressor 11 is driven in the state described above, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 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 divided and distributed 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 the indoor air taken into the interior of 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 from an outlet (not shown), thereby heating the room in which each indoor unit 3 is installed.

[0040] The refrigerant flowing from each indoor heat exchanger 51 into each indoor liquid pipe 56 is depressurized by passing through each indoor unit expansion valve 52, whose opening 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, depressurized in each indoor unit expansion valve 52, flows out from each indoor liquid pipe 56 through each liquid pipe connection 53 into the liquid pipe 4. The refrigerant that merges in the liquid pipe 4 flows into the outdoor unit 2 via 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 converted into liquid single-phase refrigerant via the SC heat exchanger 19C, and the heat-converted liquid single-phase refrigerant flows into the outdoor unit expansion valve 14. The refrigerant that flows into the outdoor unit expansion valve 14 is then depressurized as it passes through the outdoor unit expansion valve 14. The refrigerant that has been depressurized in the outdoor unit expansion valve 14 flows through the outdoor liquid pipe 25 and into the outdoor heat exchanger 13, where it evaporates by exchanging heat 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 into the outdoor refrigerant pipe 26 flows in in the following order: four-way valve 12, outdoor refrigerant pipe 26, accumulator 17, and suction pipe 22. The refrigerant is then drawn into the compressor 11, compressed again, and flows out into the outdoor gas pipe 24 via the first port 12A and fourth port 12D of the four-way valve 12.

[0042] Furthermore, when the air conditioner 1 is operating in cooling mode, 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 operates in 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 the sake of explanation, the flow of refrigerant during cooling operation is indicated by the dashed arrows shown in Figure 2.

[0043] When the compressor 11 is driven in the state of refrigerant circuit 6, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 into the four-way valve 12, and from the four-way valve 12 flows through the outdoor refrigerant pipe 26 into the outdoor heat exchanger 13. The refrigerant that flows into the outdoor heat exchanger 13 condenses by exchanging heat with the outdoor air taken 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 from an outlet (not shown).

[0044] The refrigerant flowing from the outdoor heat exchanger 13 into the outdoor liquid pipe 25 is depressurized as it passes through the outdoor unit expansion valve 14, which is set to fully open. The refrigerant depressurized in the outdoor unit expansion valve 14 flows into the SC heat exchanger 19C via the branch section 19A. The SC heat exchanger 19C exchanges heat between the refrigerant that has passed through the SC expansion valve 19B and the refrigerant flowing through the outdoor liquid pipe 25, thereby exchanging heat from the high-pressure refrigerant to a liquid single-phase refrigerant. The refrigerant that has undergone heat exchange in the SC heat exchanger 19C flows through the liquid pipe 4 via the first shut-off valve 15 and is divided to each indoor unit 3. The refrigerant that has flowed into each indoor unit 3 flows through the indoor liquid pipe 56 via each liquid pipe connection section 53 and is depressurized as it passes through the indoor unit expansion valve 52 at the refrigerant outlet of the indoor heat exchanger 51, which is adjusted to an opening degree that results in a target refrigerant subcooling degree. The refrigerant, depressurized by the indoor unit expansion valve 52, flows through the indoor liquid pipe 56 and into the indoor heat exchanger 51. There, it evaporates through heat exchange with indoor air flowing 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 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 54 flows to the outdoor gas pipe 24 via the second shut-off valve 16 of the outdoor unit 2 and enters the fourth port 12D of the four-way valve 12. The refrigerant that enters the fourth port 12D of the four-way valve 12 enters the refrigerant inlet side of the accumulator 17 through the third port 12C. The refrigerant that enters from the refrigerant inlet side of the accumulator 17 enters via the suction pipe 22 and is drawn into the compressor 11 to be compressed again.

[0046] The first acquisition unit 42 in the first control unit 20 acquires sensor values ​​from 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 sensor values ​​from 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 gaseous refrigerant flowing in from the evaporator and discharges the high-temperature, high-pressure gaseous refrigerant. The temperature of the gaseous refrigerant discharged by the compressor 11 is the discharge temperature, which is detected by the discharge temperature sensor 32.

[0049] The condenser condenses the high-temperature, high-pressure gaseous refrigerant from the compressor 11 by exchanging heat with air. During this process, after all the gaseous refrigerant has turned into liquid refrigerant due to latent heat change, the temperature of the liquid refrigerant decreases due to sensible heat change, resulting in a supercooled state. The temperature at which the gaseous refrigerant is changing into liquid refrigerant due to latent heat change is the high-pressure saturation temperature, and the temperature of the supercooled refrigerant at the outlet of the condenser is the heat exchanger outlet temperature. The high-pressure saturation temperature corresponds 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 flowing out of the condenser, resulting in a gas-liquid two-phase refrigerant mixture.

[0051] The evaporator evaporates the incoming two-phase gas-liquid refrigerant by exchanging heat with air. During this process, after the two-phase gas-liquid refrigerant has completely turned into a gaseous refrigerant due to latent heat change, the temperature of the gaseous refrigerant rises due to sensible heat change, resulting in a superheated state, which is then drawn into the compressor 11. The temperature at which the liquid refrigerant is changing into a gaseous refrigerant due to latent heat change is the low-pressure saturation temperature. The low-pressure saturation temperature corresponds 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 drawn into the compressor 11 is the suction temperature. The suction temperature is detected by the suction temperature sensor 34.

[0052] Furthermore, the degree of supercooling of a refrigerant that is in a supercooled state when it flows out of the condenser is the heat exchanger subcool, which can be calculated by subtracting the refrigerant temperature at the refrigerant outlet of the heat exchanger functioning as a condenser (the heat exchanger outlet temperature mentioned above) from the high-pressure saturation temperature. On the other hand, the degree of superheating of a 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] <Structure and generation of classification models> The classification model 430 is pre-generated using a machine learning-based classification algorithm with multiple operating state variables. These operating state variables include a first operating state variable indicating the state of the refrigerant in the condenser, a second operating state variable indicating the state of the refrigerant in the evaporator, and a third operating state variable indicating the operating state of the air conditioner 1.

[0054] Nonlinear algorithms such as random forests and neural networks are used in classification algorithms. By using nonlinear algorithms, it is possible to determine refrigerant leakage by combining values ​​that are not linearly proportional to the amount of remaining refrigerant. For example, a random forest is an ensemble learning method that combines many decision trees, with each tree learning independently and ultimately classifying by majority voting or averaging. This makes it possible to improve the prediction accuracy of the model while preventing overfitting. On the other hand, a neural network is a deep learning model consisting of multiple layers, with 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 suitable for advanced classification problems because they have a high ability to capture nonlinear relationships and complex patterns.

[0055] In generating classification model 430, the relationship between each operating state variable and the remaining refrigerant amount is first reproduced on a computer, and numerical calculations (hereinafter also referred to as simulations) are performed. The simulation generates numerical data (also referred to as data points) summarizing the relationship between each operating state variable and the remaining refrigerant amount at predetermined time intervals. Multiple data points are generated by changing each operating state variable under conditions where the remaining refrigerant amount differs (for example, 40%, 70%, 80%, 100%, 120%, etc.) and simulating refrigerant leakage and refrigerant overfilling conditions in the air conditioner. The entire dataset consisting of these data points is stored in the computer's memory.

[0056] Next, this dataset is used to train a classification model using machine learning, generating a model that classifies whether or not refrigerant is leaking based on operating state variables. In training the classification model, for example, if the remaining amount of refrigerant is 80% or more, it is labeled as "no refrigerant leak," and if the amount of refrigerant is less than 80%, it is labeled as "refrigerant leak present." Indicators such as accuracy, recall, and F1 score are used to evaluate the classification model. Finally, the optimal model is selected as classification model 430 based on these indicators.

[0057] For example, the classification model 430 takes a first operating state variable (the state of the refrigerant in the condenser), a second operating state variable (the state of the refrigerant in the evaporator), and a third operating state variable (the operating state of the air conditioner) as input, and combines this information to classify whether or not there is a refrigerant leak. The classification model 430 generated in this way can accurately recognize different patterns of operating state variables and correctly estimate whether or not there is a refrigerant leak.

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

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

[0060] The third state variable is, for example, the rotational speed of the compressor 11. However, instead of the rotational speed of the compressor 11, the third state variable may be, for example, 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, etc., and can be changed as appropriate.

[0061] Classification model 430 is generated using, for example, three operating state variables: compressor speed 11, degree of subcooling, and degree of superheating, as well as the ambient temperature. The compressor speed 11 is detected by a speed sensor (not shown) on the compressor 11. The degree of subcooling is calculated based on the condenser heat exchange outlet temperature and the condenser high-pressure saturation temperature when the outdoor heat exchanger 13 functions as a condenser. In other words, the degree of subcooling can be calculated, for example, as (high-pressure saturation temperature - heat exchange outlet temperature). The high-pressure saturation temperature is the temperature corresponding to the pressure value detected by the discharge pressure sensor 31. The heat exchange outlet temperature during cooling operation is the outdoor heat exchange outlet temperature detected by the refrigerant temperature sensor 35. The heat exchange outlet temperature during heating operation is the indoor heat exchange 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 exchange 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 values ​​can be used. The degree of supercooling during heating operation can be calculated as (high-pressure saturation temperature - indoor heat exchange outlet temperature). In this embodiment, multiple indoor units 3 are connected to one outdoor unit 2. In this case, the degree of supercooling is calculated using the operating state values ​​of the indoor units that are currently in operation. Note that the heat load (cooling capacity) that each operating indoor unit can handle may differ. In this case, it is advisable to use a weighted average value obtained by weighting the operating state values ​​of the operating indoor units by their cooling capacity.

[0062] The degree of superheating is calculated based on the intake 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 superheating can be calculated as (intake temperature - low-pressure saturation temperature), where the intake temperature is detected by the intake temperature sensor 34, and the low-pressure saturation temperature is the temperature corresponding to the pressure value detected by the intake 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 and machine learning techniques based on nonlinear algorithms such as random forests and neural networks. This makes it possible to determine with greater accuracy whether or not there is a refrigerant leak in the refrigerant circuit. A random forest is an ensemble learning model composed of many decision trees, where each tree is trained based on different subsets of the dataset. On the other hand, a neural network is a deep learning model with multiple layers and is suitable for modeling complex nonlinear relationships. In generating the classification model 430, not only simulation results but also actual operating data can be used to learn the relationship between each state variable (degree of subcooling, degree of superheating, compressor rotation speed, outside air temperature) during cooling and heating operations and the presence or absence of refrigerant leaks. During this process, parameter adjustments are made to optimize the model's performance.

[0064] As examples of classification models generated in this way, classification model 430A, used during cooling operation, and classification model 430B, used during heating operation, are given. Classification model 430A outputs whether or not there is refrigerant leakage when the rotational speed of the compressor 11, the outside air temperature, and the degree of subcooling and superheating during cooling operation are input as explanatory variables. Classification model 430B outputs whether or not there is refrigerant leakage when the rotational speed of the compressor 11, the outside air temperature, and the degree of subcooling and superheating during heating operation are input as explanatory variables.

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

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

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

[0068] As explained above, during cooling operation, the classification model used for cooling operation is used to determine whether or not there is a refrigerant leak. During heating operation, the classification model used for heating operation is used to determine whether or not there is a refrigerant leak. This makes it possible to determine whether or not there is a refrigerant leak in the refrigerant circuit 6 during both cooling and heating operation.

[0069] Figure 5A is an explanatory diagram showing an example of a modified air conditioning system 100. It illustrates a case where the classification model 430 is generated by the server device 110 and stored in the central controller 7. The air conditioning system 100 shown in Figure 5A includes an air conditioner 1, a central controller 7, a server device 110, and a communication network 120. The server device 110 is a server device that generates and stores the 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 central controller 7 has a third control unit 80. Figure 5B is a block diagram showing an example of a modified third control unit 80. 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 mentioned 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) acquires detection values ​​from various sensors via the third communication unit 81, and signals including operating 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 Figure 5A, the third control unit 84 is a refrigerant leak detection device that uses a 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 the refrigerant circulates within the refrigerant circuit 6.

[0072] <How the estimation process works> Figure 6 is a flowchart illustrating an example of the processing operation of the first control unit 20 involved in the estimation process of Embodiment 1. The first control unit 20 is assumed to hold a classification model 430 that is generated in advance for use during cooling and heating operations. In Figure 6, the first control unit 44 within the first control unit 20 collects operating state quantities as operating data through the first acquisition unit 42 (step S21). The first control unit 44 performs data filtering to extract arbitrary operating state quantities from the collected operating data (step S22). Furthermore, the first control unit 44 performs data cleansing (step S23).

[0073] The data filtering process does not use all of the multiple operating state variables, but rather, based on predetermined filtering conditions, extracts only a portion of the multiple operating state variables necessary to determine the presence or absence of refrigerant leakage. By substituting the operating state variables that have undergone data filtering (excluding abnormal and outlier values) into the generated classification model 430, the presence or absence of refrigerant leakage can be determined more accurately.

[0074] The predetermined filter conditions are, for example, filter conditions for data extracted in common for all operating modes of the air conditioner 1. The predetermined filter conditions include, for example, the drive state of the compressor 11, identification of the operating mode, exclusion of special operations, exclusion of missing values ​​in the acquired values, and selection of values ​​with small changes for operating state quantities that have a large influence on the generation of the classification model. The drive state of the compressor 11 is a condition that needs to be determined because if the compressor 11 is operating stably and refrigerant is not circulating in the refrigerant circuit 6, it is not possible to determine whether or not there is a refrigerant leak. This filter condition is set up to exclude operating state quantities detected during transient periods such as when the compressor 11 is starting up.

[0075] Identifying the operating mode is a filter condition that extracts only the operating state variables obtained during cooling and heating operations. Therefore, operating state variables obtained during dehumidification and fan operations are excluded. Excluding special operations is a filter condition that excludes operating state variables obtained during special operations, such as oil recovery operations and defrosting operations, where the state of the refrigerant circuit 6 is significantly different from that during cooling and heating operations. Excluding missing values ​​is a filter condition that excludes operating state variables containing missing values, because if there are missing values ​​in the operating state variables used to determine refrigerant leakage, generating a classification model using those operating state variables may reduce accuracy.

[0076] The selection of operating state variables with small changes for substitution into the classification model is a filtering condition that extracts only the operating state variables for the stable operating state of air conditioner 1, and is a necessary condition to improve the estimation accuracy of the classification model.

[0077] Data cleansing is a process that excludes operating state variables that may lead to incorrect determinations, rather than using all acquired operating state variables to determine the presence or absence of refrigerant leakage. Specifically, this involves smoothing the acquired operating state variables to suppress noise and limit the number of data points. Noise suppression through data smoothing involves calculating the average value for the relevant interval and then taking a moving average of, for example, the degree of subcooling, intake temperature, and superheating in each model to reduce noise. Data point limiting involves excluding data with a small number of points, for example, because it is considered unreliable. For example, if the number of data points remaining after filtering a day's worth of input data is X or more, it is used to estimate the refrigerant shortage rate; if it is less than that, all data for that day is not used. In other words, by substituting operating state variables with abnormal and outlier values ​​removed into the classification model 430 during data cleansing, the presence or absence of refrigerant leakage can be determined more accurately.

[0078] Furthermore, as part of the data cleansing process, the first control unit 44 extracts the current rotational speed of the compressor 11, the current ambient temperature, the current degree of subcooling, and the current degree of superheating. 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, it calculates the theoretical discharge 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 removes the current rotational speed of the compressor 11, the current ambient temperature, the current degree of subcooling, and the current degree of superheating that were extracted when the theoretical discharge temperature exceeds the actual discharge temperature. The first control unit 44 also uses the current rotational speed of the compressor 11, the current ambient temperature, the current degree of subcooling, and the current degree of superheating that were extracted when the theoretical discharge temperature is less than or equal to the actual discharge temperature to substitute into the classification model 430.

[0079] In Figure 6, the first control unit 44 extracts the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating from the operation data after the cleansing process (step S24). The first control unit 44 substitutes the extracted operation data of the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating into the classification model 430 (step S25). For example, during cooling operation, the first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, and the degree of subcooling and superheating during cooling operation into the classification model 430A used during cooling operation. Also, during heating operation, the first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, and the degree of subcooling and superheating during heating operation into the classification model 430B used during heating operation.

[0080] The first control unit 44 obtains a determination result regarding the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the classification model after inputting the operation data (step S26). In other words, the first control unit 44 determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during cooling operation using the classification model 430A 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 classification model 430B used during heating operation. The first control unit 44 then determines whether the determination result indicates the presence or absence of refrigerant leakage (step S27).

[0081] If the first control unit 44 determines that there is a refrigerant leak (step S27: Yes), it outputs a notification indicating that there is a refrigerant leak (step S28) and terminates the processing operation shown in Figure 6. If the first control unit 44 determines that there is no refrigerant leak (step S27: No), it outputs a notification indicating that there is no refrigerant leak (step S29) and terminates the processing operation shown in Figure 6.

[0082] <Effects of Example 1> In the air conditioner 1 of Example 1, a classification model 430 is generated using a nonlinear algorithm based on operating state variables related to determining whether or not there is refrigerant leakage in the refrigerant circuit 6, such as the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating. As a result, a classification model 430 can be generated that can determine whether or not there is refrigerant leakage circulating in the refrigerant circuit 6, even without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0083] In the air conditioner 1, the presence or absence of refrigerant leakage is estimated using the classification model 430, the current rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating. As a result, it is possible to determine whether or not there is any leakage of refrigerant circulating in the refrigerant circuit 6 at the present time, without using the opening degree of the SC expansion valve or 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 variables during cooling operation that are related to determining whether or not there is refrigerant leakage in the refrigerant circuit 6, such as the rotational speed of the compressor 11, the outside air temperature, the degree of subcooling and superheating during cooling operation, and the presence or absence of refrigerant leakage. As a result, a classification model 430A can be generated that can determine whether or not there is 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] In air conditioner 1, the presence or absence of refrigerant leakage is estimated using the classification model 430A during cooling operation, the current rotational speed of the compressor 11 during cooling operation, the outside air temperature, and the degree of subcooling and superheating during cooling operation. As a result, it is possible to determine the current 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 or 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 variables during heating operation that are related to determining whether or not there is a leak of refrigerant in the refrigerant circuit 6, such as the rotational speed of the compressor 11, the outside air temperature, and the degree of subcooling and superheating 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] In the air conditioner 1, the presence or absence of refrigerant leakage is estimated using the classification model 430B during heating operation, the current rotational speed of the compressor 11 during heating operation, the outside air temperature, and the degree of subcooling and superheating during heating operation. As a result, it is possible to determine the current presence or absence of refrigerant leakage circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve or the SC heat exchanger outlet temperature.

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

[0089] In the first control unit 20 of Example 1, the classification model 430 used is exemplified as being generated using the rotational speed, supercooling degree, and superheating degree of the compressor 11 in addition to the ambient temperature. However, the classification model 430 (430A, 430B) may also be generated using at least two of the three operating state variables (rotational speed, supercooling degree, and superheating degree of the compressor 11) and the ambient temperature, and can be modified as appropriate.

[0090] In the air conditioner 1 of Example 1, a case is illustrated in which a classification model 430 for cooling and heating operations is generated using a total of four operating state variables: the outside air temperature and three operating state variables (rotation speed of the compressor 11, degree of subcooling, and degree of superheating). As another example, a classification model 430 for cooling and heating operations may be generated using a total of three operating state variables: the outside air temperature and two operating state variables (for example, at least two of the rotation speed of the compressor 11, degree of subcooling, and degree of superheating). As in this example and other examples, by reducing the number of operating state variables used to determine the presence or absence of refrigerant leakage (for example, to four types or less), it becomes possible to determine the presence or absence of leakage without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature. It is known that reducing the number of features makes overfitting less likely, but the accuracy of the classification model may decrease. Therefore, as a method to improve the accuracy of the classification model while avoiding overfitting, an embodiment in which the presence or absence of refrigerant leakage is determined by combining three of the four types of operating state variables to generate multiple (three types) classification models, and using the judgment result that receives the most votes from each classification model (taking a majority vote on the judgment results), is described below as Example 2. Note that the same reference numerals are used for components identical to those of the air conditioner 1 in Example 1, and the explanation of the redundant components and operations is omitted. [Examples]

[0091] Figure 7 is a block diagram showing an example of the first control unit 20A of Embodiment 2. The difference between the air conditioner 1 of Embodiment 1 and the air conditioner 1 of Embodiment 2 is that, instead of the classification model 430 used during cooling and heating operations, the first classification model 431, the second classification model 432, and the third classification model 433 are used. In Figure 7, the first memory unit 43A in the first control unit 20A stores the first classification model 431, the second classification model 432, and the third classification model 433.

[0092] <Structure of the classification model> Figure 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 operating state variables, namely the rotational speed of the compressor 11, the outside air temperature, the degree of subcooling, and a leak / normal label. The first classification model 431 has 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 rotational speed of the compressor 11, the outside air temperature, the degree of subcooling during cooling operation (high-pressure saturation temperature - outdoor heat exchange outlet temperature), and a leak / normal label. The first classification model 431B used during heating operation is generated using the rotational speed of the compressor 11, the outside air temperature, the degree of subcooling during heating operation (high-pressure saturation temperature - indoor heat exchange outlet temperature), and whether or not there is refrigerant leakage.

[0093] The second classification model 432 is a learning model generated using the operating state variables, namely the rotational speed of the compressor 11, the ambient temperature, the degree of superheating, and the presence or absence of refrigerant leakage. 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 rotational speed of the compressor 11, the ambient temperature, the degree of superheating, and the presence or absence of refrigerant leakage. The second classification model 432B used during heating operation is generated using the rotational speed of the compressor 11, the ambient temperature, the degree of superheating, and a leak / normal label.

[0094] The third classification model 433 is a learning model generated using the ambient temperature, degree of subcooling, and degree of superheating among the operating state variables. 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 ambient temperature, the degree of subcooling during cooling operation (high-pressure saturation temperature - outdoor heat exchange outlet temperature), the degree of superheating, and a leak / normal label. The third classification model 433B used during heating operation is generated using the ambient temperature, the degree of subcooling during heating operation (high-pressure saturation temperature - indoor heat exchange outlet temperature), the degree of superheating, and whether or not there is refrigerant leakage.

[0095] <How the estimation process works> Figure 9 is a flowchart illustrating an example of the processing operation of the first control unit 20A involved in the estimation process of Embodiment 2. The first control unit 20A is assumed to hold a pre-generated first classification model 431, a second classification model 432, and a third classification model 433. In Figure 9, the first control unit 44 within the first control unit 20A collects operating state quantities as operating data through the first acquisition unit 42 (step S31). The first control unit 44 performs data filtering to extract arbitrary operating state quantities from the collected operating data (step S32). The first control unit 44 performs data cleansing (step S33).

[0096] The data filtering process does not use all of the multiple operating state variables, but rather, based on predetermined filtering conditions, extracts only a portion of the multiple operating state variables necessary to determine the presence or absence of refrigerant leakage. By substituting the data-filtered operating state variables (excluding abnormal and outlier values) into the generated classification model, the presence or absence of refrigerant leakage can be determined more accurately.

[0097] The data cleansing process is designed to exclude operating state variables that may lead to an incorrect determination, rather than using all acquired operating state variables to determine whether or not there is a refrigerant leak.

[0098] Furthermore, as part of the data cleansing process, the first control unit 44 extracts the current rotational speed of the compressor 11, the current ambient temperature, the current degree of subcooling, and the current degree of superheating. 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, it calculates the theoretical discharge 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 removes the current rotational speed of the compressor 11, the current ambient temperature, the current degree of subcooling, and the current degree of superheating that were extracted when the theoretical discharge temperature exceeds the actual discharge temperature. The first control unit 44 then uses the current rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the current degree of superheating that were extracted when the theoretical discharge temperature is less than or equal to the actual discharge temperature to substitute into the classification models of the first classification model 431, the second classification model 432, and the third classification model 433.

[0099] In Figure 9, the first control unit 44 extracts the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating from the operation data after the cleansing process (step S34). The first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, and the degree of subcooling extracted in step S34 into the first classification model of the first classification model 431 (step S35A). For example, during cooling operation, the first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, and the degree of subcooling during cooling operation into the classification model of the first classification model 431 used during cooling operation. Also, during heating operation, the first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, and the degree of subcooling during heating operation into the classification model of the first classification model 431 used during heating operation.

[0100] The first control unit 44 obtains a determination result regarding the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the first classification model after the operation data has been substituted (step S36A). In other words, 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 voting process in step S38, which will be described later.

[0101] Furthermore, after processing in step S34, the first control unit 44 substitutes the extracted operating data of the compressor 11's rotational speed, ambient temperature, and 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 compressor 11's rotational speed, ambient temperature, and superheat into the second classification model of the second classification model 432A used during cooling operation. Also, during heating operation, the first control unit 44 substitutes the operating data of the compressor 11's rotational speed, ambient temperature, and 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 regarding the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the second classification model after the operation data has been substituted (step S36B). In other words, 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 of 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 of 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 voting process in step S38, which will be described later.

[0103] Furthermore, after processing in step S34, the first control unit 44 substitutes the extracted operating data of ambient temperature, degree of subcooling, and 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 ambient temperature, degree of subcooling, and degree of superheating during cooling operation into the third classification model of the third classification model 433A used during cooling operation. Also, during heating operation, the first control unit 44 substitutes the operating data of ambient temperature, degree of subcooling, and degree of superheating during heating operation into the third classification model of the third classification model 433B used during heating operation.

[0104] The first control unit 44 obtains a determination result regarding 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). In other words, 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 voting process in step S38, which will be described later.

[0105] The first control unit 44 performs a majority vote process to determine whether a refrigerant leak is present based on the determination results of the first classification model 431, the second classification model 432, and the third classification model 433 (step S38). The majority vote process counts the number of determination results indicating refrigerant leak and the number of determination results indicating no refrigerant leak, respectively, based on the determination results of the first classification model 431, the second classification model 432, and the third classification model 433. The majority vote process then compares the number of determination results indicating refrigerant leak and the number of determination results indicating no refrigerant leak to determine the majority of the determination results.

[0106] The first control unit 44 determines whether the majority vote indicates that there is a refrigerant leak (step S39). If the majority vote indicates that there is a refrigerant leak (step S39: Yes), the first control unit 44 outputs a notification indicating that there is a refrigerant leak (step S40) and terminates the processing operation shown in Figure 9.

[0107] Furthermore, if the majority vote result indicates that there is a refrigerant leak (step S39: No), the first control unit 44 outputs a notification indicating no refrigerant leak (step S41) and terminates the processing operation shown in Figure 9.

[0108] <Effects of Example 2> In the air conditioner 1 of Example 2, a first classification model 431 is generated using the rotational speed of the compressor 11, the ambient temperature, and the degree of supercooling; a second classification model 432 is generated using the rotational speed of the compressor 11, the ambient temperature, and the degree of superheating; and a third classification model 433 is generated using the ambient temperature, the degree of supercooling, and the degree of superheating. As a result, overfitting can be avoided by generating three classification models by combining three of the four types of operating state variables.

[0109] In the air conditioner 1, a majority vote is taken to determine whether or not there is a refrigerant leak using the judgment results of the first classification model 431, the second classification model 432, and the third classification model 433. Then, the air conditioner 1 determines whether or not there is a refrigerant leak based on the result of the majority vote. As a result, compared to using the classification model 430 of Example 1, using a majority vote of the judgment results allows for a more accurate determination of whether or not there is a refrigerant leak.

[0110] In the air conditioner 1, a first classification model 431A for use during cooling operation is generated by a nonlinear algorithm using operating state variables during cooling operation that are related to determining whether or not there is refrigerant leakage, such as the rotational speed of the compressor 11, the outside air temperature, and the degree of subcooling during cooling operation, as well as whether or not there is refrigerant leakage. As a result, a first classification model 431A can be generated that can determine whether or not there is 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.

[0111] In the air conditioner 1, the presence or absence of refrigerant leakage is estimated using the first classification model 431A used during cooling operation, the current rotational 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 leakage of refrigerant circulating in the refrigerant circuit 6 during cooling operation without using the opening degree of the SC expansion valve or the SC heat exchanger outlet temperature.

[0112] In the air conditioner 1, a first classification model 431B for use during heating operation is generated by a nonlinear algorithm using operating state variables during heating operation that are related to determining whether or not there is refrigerant leakage, such as the rotational speed of the compressor 11, the outside air temperature, and the degree of subcooling during heating operation, along with the presence or absence of refrigerant leakage. As a result, a first classification model 431B can be generated that can determine whether or not there is refrigerant leakage 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] In the air conditioner 1, the presence or absence of refrigerant leakage is estimated using the first classification model 431B used during heating operation, the current rotational 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 whether or not there is current leakage of refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve or the SC heat exchanger outlet temperature.

[0114] In the air conditioner 1, a second classification model 432A for use during cooling operation is generated by a nonlinear algorithm using operating state variables during cooling operation that are related to determining whether or not there is refrigerant leakage in the refrigerant circuit 6, such as the rotational speed of the compressor 11, the outside air temperature, and the degree of superheating, and the presence or absence of refrigerant leakage. As a result, a second classification model 432A can be generated that can determine whether or not there is 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] In the air conditioner 1, the presence or absence of refrigerant leakage is estimated using the second classification model 432A used during cooling operation, along with the current rotational speed of the compressor 11, the outside air temperature, and the degree of superheating during cooling operation. As a result, it is possible to determine the current 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 or the SC heat exchanger outlet temperature.

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

[0118] In the air conditioner 1, a third classification model 433A for use during cooling operation is generated by a nonlinear algorithm using operating state variables during cooling operation that are related to determining the presence or absence of refrigerant leakage, such as the outside air temperature, the degree of subcooling and superheating during cooling operation, and the presence or absence of refrigerant leakage. As a result, a third classification model 433A 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 exchange outlet temperature.

[0119] In air conditioner 1, the presence or absence of refrigerant leakage is estimated using the third classification model 433A used during cooling operation, the current outside air temperature during cooling operation, and the degree of subcooling and superheating during cooling operation. As a result, it is possible to determine the current 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 exchange outlet temperature.

[0120] In the air conditioner 1, a third classification model 433B for use during heating operation is generated by a nonlinear algorithm using operating state variables during heating operation that are related to determining whether or not there is refrigerant leakage, such as the outside air temperature, the degree of subcooling and superheating during heating operation, and the presence or absence of refrigerant leakage. As a result, a third classification model 433B can be generated that can determine whether or not there is refrigerant leakage 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] In air conditioner 1, the presence or absence of refrigerant leakage is estimated using the third classification model 433B used during heating operation, the current outside air temperature during heating operation, and the degree of subcooling and superheating during heating operation. As a result, it is possible to determine the presence or absence of current leakage of refrigerant circulating in the refrigerant circuit 6 during heating operation without using the opening degree of the SC expansion valve or the SC heat exchanger outlet temperature.

[0122] In Examples 1 and 2, the air conditioner 1 was illustrated using a refrigerant circuit employing an SC heat exchanger. However, since the invention is also applicable to refrigerant circuits that do not employ an SC heat exchanger, such an embodiment will be described as Example 3. Components identical to those in Example 1 of the air conditioner 1 are denoted by the same reference numerals, and the explanation of redundant components and operations will be omitted. [Examples]

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

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

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

[0126] When the air conditioner 1A is operating in heating mode, the four-way valve 12 is switched so that the first port 12A and the fourth port 12D are in communication, and the second port 12B and the third port 12C are in communication. As a result, the refrigerant circuit 6A operates in 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 the sake of explanation, the flow of refrigerant during heating operation is indicated by the solid arrows shown in Figure 10.

[0127] When the compressor 11 is driven in the state described above, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 into the four-way valve 12, then flows from the four-way valve 12 into the outdoor gas pipe 24, and flows into the gas pipe 5 via the second shut-off valve 16. The refrigerant flowing through the gas pipe 5 is divided and distributed 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 flows into each indoor heat exchanger 51. The refrigerant that flows into each indoor heat exchanger 51 condenses by exchanging heat with the indoor air taken into the interior of 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 from an outlet (not shown), thereby heating the room in which each indoor unit 3 is installed.

[0128] The refrigerant flowing from each indoor heat exchanger 51 into each indoor liquid pipe 56 is depressurized by passing through each indoor unit expansion valve 52, whose opening 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, depressurized by each indoor unit expansion valve 52, flows out from each indoor liquid pipe 56 through each liquid pipe connection 53 into the liquid pipe 4. The refrigerant that merges in the liquid pipe 4 flows into the outdoor unit 2 via 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 depressurized after passing through the outdoor unit expansion valve 14. The refrigerant that is depressurized by the outdoor unit expansion valve 14 flows through the outdoor liquid pipe 25 and into the outdoor heat exchanger 13, where it evaporates by exchanging heat 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 into the outdoor refrigerant pipe 26 flows in in the following order: four-way valve 12, outdoor refrigerant pipe 26, accumulator 17, and suction pipe 22. The refrigerant is then drawn into the compressor 11, compressed again, and flows out to 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 in communication, and the third port 12C and the fourth port 12D are in communication. As a result, the refrigerant circuit 6A operates in 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 the sake of explanation, the flow of refrigerant during cooling operation is indicated by the dashed arrows shown in Figure 10.

[0131] When the compressor 11 is driven in the state of refrigerant circuit 6A, the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 into the four-way valve 12, and from the four-way valve 12 flows through the outdoor refrigerant pipe 26 into the outdoor heat exchanger 13. The refrigerant that flows into the outdoor heat exchanger 13 condenses by exchanging heat with the outdoor air taken 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 from an outlet (not shown).

[0132] The refrigerant flowing from the outdoor heat exchanger 13 into the outdoor liquid pipe 25 is depressurized as it passes through the outdoor unit expansion valve 14, which is set to fully open. The refrigerant depressurized by the outdoor unit expansion valve 14 flows through the liquid pipe 4 via the first shut-off valve 15 and is divided to each indoor unit 3. The refrigerant flowing into each indoor unit 3 flows through the indoor liquid pipe 56 via each liquid pipe connection 53 and is depressurized as it passes through the indoor unit expansion valve 52 at the refrigerant outlet of the indoor heat exchanger 51, which is adjusted to an opening degree that results in the target refrigerant subcooling degree. The refrigerant depressurized 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 flowing 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 into the room from an 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 54 flows to the outdoor gas pipe 24 via the second shut-off valve 16 of the outdoor unit 2 and enters the fourth port 12D of the four-way valve 12. The refrigerant that enters the fourth port 12D of the four-way valve 12 enters the refrigerant inlet side of the accumulator 17 through the third port 12C. The refrigerant that enters from the refrigerant inlet side of the accumulator 17 enters via the suction pipe 22 and is drawn into the compressor 11 to be compressed again.

[0134] During cooling operation of 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 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, for example, using at least two of the three operating state variables of the compressor 11 (rotational speed, degree of subcooling, and degree of superheating), the ambient temperature, and the presence or absence of refrigerant leakage. The classification model 430 consists of classification model 430A, used during cooling operation, and classification model 430B, used during heating operation, which determine whether or not there is refrigerant leakage in the refrigerant circuit 6A.

[0136] The first control unit 44 then extracts the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating from the operation data after the cleansing process. The first control unit 44 then substitutes the extracted operation data of the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating into the classification model of classification model 430. For example, during cooling operation, the first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating into the classification model of classification model 430A, which is used during cooling operation. Also, during heating operation, the first control unit 44 substitutes the operation data of the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating into the classification model of classification model 430B, which is used during heating operation.

[0137] The first control unit 44 obtains a determination result regarding the presence or absence of refrigerant leakage in the refrigerant circuit 6 using the classification model after the operation data has been substituted. In other words, the first control unit 44 determines the presence or absence of refrigerant leakage in the refrigerant circuit 6 during cooling operation using the classification model 430A 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 classification model 430B used during heating operation. The first control unit 44 determines whether the determination result indicates that there is refrigerant leakage. If the determination result indicates that there is refrigerant leakage, the first control unit 44 outputs a notification indicating that there is refrigerant leakage. If the determination result indicates that there is no refrigerant leakage, the first control unit 44 outputs a notification indicating that there is no refrigerant leakage.

[0138] <Effects of Example 3> In the air conditioner 1A of Example 3, a classification model 430 is generated by a nonlinear algorithm using operating state variables related to determining whether or not there is refrigerant leakage in the refrigerant circuit 6A, the rotational speed of the compressor 11, the ambient temperature, the degree of subcooling, and the degree of superheating. As a result, a classification model 430 can be generated that can determine whether or not there is refrigerant leakage in the refrigerant circuit 6A, which does not have an injection circuit 19 including the SC heat exchanger 19C, without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature.

[0139] In air conditioner 1A, the presence or absence of refrigerant leakage is estimated using classification model 430, the current rotational speed of compressor 11, ambient temperature, degree of subcooling, and degree of superheating. As a result, it is possible to determine whether or not there is current refrigerant leakage in the refrigerant circuit 6A without using the opening degree of the SC expansion valve or the SC heat exchanger outlet temperature.

[0140] Furthermore, while the air conditioner 1A in Example 3 exemplifies the use of classification model 430, the first classification model 431, the second classification model 432, and the third classification model 433 may also be used, as in the air conditioner 1 of Example 2.

[0141] In the air conditioner 1A, a first classification model 431 is generated using the rotational speed of the compressor 11, the ambient temperature, and the degree of supercooling; a second classification model 432 is generated using the rotational speed of the compressor 11, the ambient temperature, and the degree of superheating; and a third classification model 433 is generated using the ambient temperature, the degree of supercooling, and the degree of superheating. As a result, overfitting can be avoided by generating three classification models by combining three of the four types of operating state variables.

[0142] In air conditioner 1A, a majority vote is taken to determine whether or not there is a refrigerant leak using the judgment results of the first classification model 431, the second classification model 432, and 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 by using a majority vote of the judgment results compared to using classification model 430.

[0143] In this embodiment, the simulation results for each operating state quantity are obtained during the design phase of the air conditioner 1, and the classification model 430 obtained by training the first control unit 44 in the outdoor unit 2, which has a learning function, is stored in the first storage unit 43. However, the embodiment is not limited to this. For example, as shown in the modified example of Embodiment 1, there may be a server connected to the air conditioner 1 via a communication network, and this server may perform 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 can be modified as appropriate.

[0144] In addition, in the air conditioner 1 (1A) of Examples 1 to 3, a classification model 430 was provided to determine whether or not refrigerant leakage occurred when N indoor units 3 were connected to one outdoor unit 2. However, the presence or absence of refrigerant leakage can also be determined in the same way as in Examples 1 to 3 for an air conditioner 1 in which one outdoor unit 2 and one indoor unit 3 are connected.

[0145] Furthermore, the components of each part shown in the diagram do not necessarily have to be physically configured as depicted. In other words, the specific forms of distribution and integration of each part are not limited to those shown in the diagram, and all or part of them can be functionally or physically distributed and integrated in any unit according to 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 MCU (Micro Controller Unit)). It goes without saying that the various processing functions may also 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 wired logic hardware.

[0147] Incidentally, the various processes described in this embodiment can be realized by executing a pre-prepared refrigerant leak detection program on, for example, the first control unit 20 or an information processing device connected to the air conditioner 1. The first control unit 20 or the information processing device executes the refrigerant leak detection program and performs a process to learn a classification model by associating at least two of the following state quantities—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—with the presence or absence of refrigerant leakage. As a result, a classification model 430 can be generated that can determine whether or not there is refrigerant leakage circulating in the refrigerant circuit 6, even without using the opening degree of the SC expansion valve and the SC heat exchanger outlet temperature. [Explanation of Symbols]

[0148] 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 Models 431 First Classification Model 432 Second Classification Model 433 Third Classification Model 44 First control unit 51 Indoor heat exchanger

Claims

1. A refrigerant leak detection device for 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, wherein the outdoor unit and the indoor unit are connected by refrigerant piping to form a refrigerant circuit, and the refrigerant circulates within the refrigerant circuit, wherein the refrigerant leak detection device determines whether the refrigerant is leaking, The control unit comprises: a first classification model that learns by associating the degree of subcooling, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the condenser of the air conditioner, with the presence or absence of refrigerant leakage; a second classification model that learns by associating the degree of superheating, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the evaporator of the air conditioner, with the presence or absence of refrigerant leakage; and a third classification model that learns by associating the degree of subcooling, ambient temperature, and superheating with the presence or absence of refrigerant leakage. The control unit, A refrigerant leak detection device characterized by determining whether or not there is a refrigerant leak in the refrigerant circuit using the first classification model, the second classification model, and the third classification model.

2. The control unit, The refrigerant leak detection device according to claim 1, characterized in that it determines whether or not there is a refrigerant leak in the refrigerant circuit using the determination results of the first classification model, the second classification model, and the third classification model, which are the majority of determination results.

3. The control unit, If the outdoor heat exchanger functions as a condenser, the degree of supercooling is calculated based on the heat exchanger outlet temperature and the high-pressure saturation temperature of the condenser. The refrigerant leak detection device according to claim 1, characterized in that, when the outdoor heat exchanger functions as an evaporator, the degree of superheating is calculated based on the suction temperature of the compressor and the low-pressure saturation temperature of the compressor.

4. An air conditioner comprising an outdoor unit having a compressor, an outdoor heat exchanger and an expansion valve, and an indoor unit having an indoor heat exchanger, wherein the outdoor unit and the indoor unit are connected by refrigerant piping to form a refrigerant circuit, and an air conditioner comprising a refrigerant leak detection device for determining refrigerant leakage in an air conditioner in which refrigerant circulates within the refrigerant circuit, The refrigerant leak detection device is The control unit comprises: a first classification model that learns by associating the degree of subcooling, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the condenser of the air conditioner, with the presence or absence of refrigerant leakage; a second classification model that learns by associating the degree of superheating, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the evaporator of the air conditioner, with the presence or absence of refrigerant leakage; and a third classification model that learns by associating the degree of subcooling, ambient temperature, and superheating with the presence or absence of refrigerant leakage. The control unit, An air conditioner characterized by determining whether or not there is a refrigerant leak in the refrigerant circuit using the first classification model, the second classification model, and the third classification model.

5. The aforementioned refrigerant circuit is The air conditioner according to claim 4, characterized in that it is equipped with a subcooling heat exchanger positioned between the outdoor heat exchanger and the indoor heat exchanger.

6. A refrigerant leak detection device for 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, wherein the outdoor unit and the indoor unit are connected by refrigerant piping to form a refrigerant circuit, and the refrigerant circulates within the refrigerant circuit, wherein the refrigerant leak detection device determines whether the refrigerant is leaking, A first classification model is learned by associating the degree of subcooling, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the condenser of the air conditioner, with the presence or absence of refrigerant leakage; a second classification model is learned by associating the degree of superheating, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the evaporator of the air conditioner, with the presence or absence of refrigerant leakage; and a third classification model is learned by associating the degree of subcooling, ambient temperature, and superheating with the presence or absence of refrigerant leakage. The presence or absence of refrigerant leakage in the refrigerant circuit is determined using the first classification model, the second classification model, and the third classification model. A refrigerant leak detection program characterized by executing a process.

7. A refrigerant leak detection device for 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, wherein the outdoor unit and the indoor unit are connected by refrigerant piping to form a refrigerant circuit, and the refrigerant circulates within the refrigerant circuit, is provided, A first classification model is learned by associating the degree of subcooling, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the condenser of the air conditioner, with the presence or absence of refrigerant leakage; a second classification model is learned by associating the degree of superheating, ambient temperature, and compressor rotation speed, which indicate the state of the refrigerant in the evaporator of the air conditioner, with the presence or absence of refrigerant leakage; and a third classification model is learned by associating the degree of subcooling, ambient temperature, and superheating with the presence or absence of refrigerant leakage. The presence or absence of refrigerant leakage in the refrigerant circuit is determined using the first classification model, the second classification model, and the third classification model. A method for determining refrigerant leakage, characterized by performing a process.

Images