State management device, state management method, and air conditioning system

Abstract

A state management device according to one embodiment of the present invention manages the state of an outdoor unit of an air conditioning device having a compressor, an outdoor heat exchanger, and a flow path switching valve. The state management device: acquires information relating to the operating state of the compressor, a discharge temperature, which is a detected value of the temperature of a refrigerant on the refrigerant discharge side of the compressor, a suction temperature, which is a detected value of the temperature of the refrigerant on the refrigerant suction side of the compressor, and an outside air temperature, which is a detected value of the air temperature outdoors, where the outdoor unit is installed; when the compressor stops, outputs an estimated suction temperature, which is an estimated value of the suction temperature immediately after the compressor stops, using the discharge temperature acquired immediately before and immediately after the compressor stops, the suction temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops; and determines the presence or absence of an abnormality in the flow path switching valve by comparing the suction temperature acquired immediately after the compressor stops with the estimated suction temperature.

Description

State management apparatus, state management method and air conditioning system

[0001] The present invention relates to a state management apparatus, a state management method, and an air conditioning system for managing the state of an air conditioner.

[0002] An air conditioner having a refrigerant circuit includes a four-way valve (flow path switching valve) that switches the refrigerant circuit between a heating cycle and a cooling cycle by switching the flow direction of refrigerant. For example, Patent Document 1 discloses, as a method for determining abnormality of a four-way valve, that when the temperature difference between the temperature of refrigerant flowing through an indoor heat exchanger and room temperature is equal to or less than a predetermined value, the presence or absence of an abnormality of the four-way valve (abnormality in the position of the valve body of the four-way valve) is determined based on the temperature difference between the temperature of refrigerant discharged from a compressor and the temperature of refrigerant sucked into the compressor.

[0003] That is, in Patent Document 1, when the temperature difference between the temperature of refrigerant flowing through an indoor heat exchanger and room temperature is equal to or less than a predetermined value, it is determined that sufficient refrigerant has not flowed into the indoor unit and the refrigerant temperature is close to room temperature. When the temperature difference between the temperature of refrigerant discharged from the compressor and the temperature of refrigerant sucked into the compressor is equal to or less than a predetermined value, it is determined that the refrigerant discharged from the compressor is sucked into the compressor as it is, and therefore the four-way valve is abnormal.

[0004] Japanese Unexamined Patent Application Publication No. 2020-148405

[0005] However, for causes other than the above-mentioned abnormality of the four-way valve, for example, the magnitude of the air conditioning load of the indoor unit, or when the indoor unit is in a thermo-off state, the temperature difference between the temperature of refrigerant flowing through the indoor heat exchanger and room temperature may also become equal to or less than a predetermined value. That is, with the method described in Patent Document 1, depending on the operating state of the indoor unit, the temperature difference between the temperature of refrigerant flowing through the indoor heat exchanger and room temperature may become equal to or less than a predetermined value, and there is a risk that the determination process is performed even though an abnormality determination for the four-way valve is not originally required.

[0006] Furthermore, when the compressor's operating capacity is reduced, the temperature of the refrigerant discharged from the compressor and the temperature of the refrigerant drawn into the compressor may approach each other. Therefore, if the above predetermined values ​​are not set with sufficient margin, the four-way valve may be misidentified as malfunctioning even when it is functioning normally. In addition, if the compressor malfunctions or the refrigerant charge amount is incorrect, the above temperatures may also approach each other, potentially leading to a misidentification of a malfunction other than the four-way valve as a malfunction of the four-way valve.

[0007] Furthermore, Patent Document 1 does not provide specific details on which indoor unit to use to determine the temperature difference between the refrigerant temperature flowing through the indoor heat exchanger and the room temperature in the case of an air conditioning system in which multiple indoor units are connected to one outdoor unit, or how to handle the temperature difference in each indoor unit. Therefore, in an air conditioning system equipped with multiple indoor units, it may not be possible to accurately determine whether or not a four-way valve abnormality detection process is necessary. Moreover, in the method of determining a four-way valve abnormality using the temperature difference between the discharge temperature and the intake temperature, as described in Patent Document 1, if the displacement of the valve body of the four-way valve is slight, the amount of refrigerant discharged from the compressor that flows to the intake side of the compressor is also small. Therefore, even if the four-way valve is abnormal, it may not be possible to determine that the four-way valve is abnormal because the difference between the temperature of the refrigerant discharged from the compressor and the temperature of the refrigerant drawn into the compressor does not fall below a predetermined value.

[0008] In view of the above circumstances, the object of the present invention is to provide an air conditioning system condition management device, a condition management method, and an air conditioning system that can accurately determine whether or not there is an abnormality in a flow path switching valve such as a four-way valve, regardless of the operating status of the indoor unit or the number of indoor units in operation.

[0009] A state management device according to one embodiment of the present invention is a state management device for managing the state of an outdoor unit of an air conditioning system having a compressor, an outdoor heat exchanger, and a flow path switching valve, and comprises an acquisition unit and a control unit. The acquisition unit acquires information relating to the operating state of the compressor, a discharge temperature which is a detected value of the temperature of the refrigerant on the refrigerant discharge side of the compressor, an intake temperature which is a detected value of the temperature of the refrigerant on the refrigerant suction side of the compressor, and an outside air temperature which is a detected value of the temperature of the outside air where the outdoor unit is installed. When the compressor stops, the control unit outputs an estimated intake temperature which is an estimated value of the intake temperature immediately after the compressor stops, using the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops, and determines whether or not there is an abnormality in the flow path switching valve by comparing the intake temperature acquired immediately after the compressor stops with the estimated intake temperature.

[0010] The above-mentioned condition management device determines whether or not there is a malfunction in the flow path switching valve based only on parameters detectable by the outdoor unit, thus accurately determining whether or not there is a malfunction in the flow path switching valve without being affected by the number of indoor units or their operating status. Furthermore, by comparing the intake temperature acquired immediately after the compressor stops with the estimated intake temperature, it is possible to determine whether or not there is a malfunction in the flow path switching valve, for example, by detecting early signs of a malfunction in the flow path switching valve from fluctuations in intake temperature caused by a positional abnormality of the valve body.

[0011] A state management method according to one embodiment of the present invention is a state management method for managing the state of an outdoor unit of an air conditioning system having a compressor, an outdoor heat exchanger, and a flow path switching valve, and the method acquires information regarding the operating state of the compressor, a discharge temperature which is a detected value of the temperature of the refrigerant on the refrigerant discharge side of the compressor, an intake temperature which is a detected value of the temperature of the refrigerant on the refrigerant suction side of the compressor, and an outside air temperature which is a detected value of the temperature of the outside air where the outdoor unit is installed, and when the compressor stops, an estimated intake temperature which is an estimated value of the intake temperature immediately after the compressor stops, is calculated using the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops, and the presence or absence of an abnormality in the flow path switching valve is determined by comparing the estimated intake temperature with the intake temperature acquired immediately after the compressor stops.

[0012] An air conditioning system according to one embodiment of the present invention comprises an air conditioning device and a state management device. The air conditioning device includes a compressor, an outdoor unit having an outdoor heat exchanger and a flow path switching valve, an indoor unit having an indoor heat exchanger, and a refrigerant circuit including refrigerant piping connecting the outdoor unit and the indoor unit. The state management device manages the state of the outdoor unit. The state management device includes an acquisition unit and a control unit. The acquisition unit acquires information relating to the operating state of the compressor, a discharge temperature which is a detected value of the refrigerant temperature on the refrigerant discharge side of the compressor, an intake temperature which is a detected value of the refrigerant temperature on the refrigerant suction side of the compressor, and an outside air temperature which is a detected value of the outdoor air temperature where the outdoor unit is installed. When the compressor stops, the control unit outputs an estimated intake temperature, which is an estimated value of the intake temperature immediately after the compressor stops, using the discharge temperature obtained immediately before and immediately after the compressor stops, the intake temperature obtained immediately before the compressor stops, and the ambient temperature obtained immediately before or immediately after the compressor stops. The control unit then determines whether or not there is an abnormality in the flow path switching valve by comparing the intake temperature obtained immediately after the compressor stops with the estimated intake temperature.

[0013] According to the present invention, it is possible to accurately determine whether or not there is an abnormality in a flow path switching valve such as a four-way valve, regardless of the operating status of the indoor unit or the number of indoor units in operation.

[0014] This is a schematic diagram of an air conditioning system according to one embodiment of the present invention. This is a block diagram showing the configuration of a control device in an air conditioning system. This is a block diagram showing the configuration of a state management device according to one embodiment of the present invention. This is a schematic diagram illustrating the configuration and state of a four-way valve as a flow path switching valve. This is a flowchart showing an example of a processing procedure performed in a state management device according to one embodiment of the present invention. This is a flowchart showing an example of an abnormality determination process performed in a state management device according to one embodiment of the present invention.

[0015] Embodiments of the present invention will be described below with reference to the drawings.

[0016] Figure 1 is a schematic diagram of an air conditioning system 1 according to one embodiment of the present invention. The air conditioning system 1 comprises an air conditioning device 100 and a condition management device 200.

[0017] [Air Conditioning System] The air conditioning system 100 is a cooling / heating switching type air conditioner equipped with multiple indoor units, which perform either cooling or heating in all indoor units. In this embodiment, the air conditioning system 100 in which three indoor units 8a, 8b, and 8c are connected in parallel to one outdoor unit 2 will be described as an example.

[0018] As shown in Figure 1, the air conditioning system 100 comprises an outdoor unit 2 and three indoor units 8a, 8b, and 8c. The refrigerant circuit 10 of the air conditioning system 100 is formed by the interconnection of the outdoor unit 2 and the indoor units 8a to 8c by liquid pipes 31 and gas pipes 32. In this embodiment, the outdoor unit 2 has one outdoor heat exchanger 24, but it may have two or more outdoor heat exchangers.

[0019] (Outdoor unit) The outdoor unit 2 is equipped with a compressor 21, a four-way valve 22, an outdoor heat exchanger 24, an outdoor fan 26, an accumulator 27, and an outdoor expansion valve 29.

[0020] The compressor 21 is a variable-capacity compressor whose operating capacity is variable, driven by a motor (not shown) whose rotational speed is controlled by an inverter. The refrigerant discharge port of the compressor 21 is connected to port a of the four-way valve 22 by a discharge pipe 28. The refrigerant suction port of the compressor 21 is connected to the outlet side of the accumulator 27 by a suction pipe 42.

[0021] The four-way valve 22 is a flow path switching valve for switching the direction of refrigerant flow in the refrigerant circuit 10, switching the connection of one refrigerant inlet / outlet of the outdoor heat exchanger 24 to either the refrigerant outlet or refrigerant inlet of the compressor 21. The four-way valve 22 has four ports: a, b, c, and d. Port a is connected to the refrigerant outlet of the compressor 21 by the discharge pipe 28. Port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 24 by the refrigerant pipe 37. Port c is connected to the inlet side of the accumulator 27 by the refrigerant pipe 36. Port d is connected to the gas side shut-off valve 46 by the outdoor unit gas pipe 34. The detailed structure and operation of the four-way valve 22 will be explained later using Figure 4.

[0022] One refrigerant inlet / outlet of the outdoor heat exchanger 24 is connected to port b of the four-way valve 22 via refrigerant piping 37, as described above, and the other refrigerant inlet / outlet of the outdoor heat exchanger 24 is connected to one port of the outdoor expansion valve 29. The other port of the outdoor expansion valve 29 is connected to the liquid side shut-off valve 45 and the outdoor unit liquid pipe 35. The outdoor heat exchanger 24 functions as a condenser during cooling operation and as an evaporator during heating operation, depending on the switching of the four-way valve 22.

[0023] The accumulator 27 has its inlet side connected to port c of the four-way valve 22 by refrigerant piping 36, and its outlet side connected to the refrigerant inlet of the compressor 21 by suction piping 42. The accumulator 27 separates the incoming refrigerant into gaseous refrigerant and liquid refrigerant, and allows only the gaseous refrigerant to be drawn into the compressor 21.

[0024] The outdoor fan 26 is positioned near the outdoor heat exchanger 24. The outdoor fan 26 rotates using a fan motor (not shown) to draw outside air into the outdoor unit 2, exchange heat between the refrigerant and the outside air in the outdoor heat exchanger 24, and then releases the heat-exchanged outside air to the outside of the outdoor unit 2.

[0025] The outdoor expansion valve 29 is an electronic expansion valve driven by a pulse motor (not shown) and is located in the outdoor unit liquid pipe 35. Specifically, the opening degree of the outdoor expansion valve 29 is adjusted to an opening degree between fully closed and fully open by the number of pulses applied to the pulse motor. The opening degree of the outdoor expansion valve 29 is adjusted according to the heating capacity required by the indoor units 8a to 8c during heating operation, and according to the cooling capacity required by the indoor units 8a to 8c during cooling operation.

[0026] The outdoor unit 2 is equipped with various sensors. As shown in Figure 1, the discharge pipe 28 is equipped with a high-pressure sensor 50 that detects the discharge pressure, which is the pressure of the refrigerant discharged from the compressor 21, and a discharge temperature sensor 53 that detects the discharge temperature, which is the temperature of the refrigerant discharged from the compressor 21. The suction pipe 42 is equipped with a low-pressure sensor 51 that detects the suction pressure, which is the pressure of the refrigerant drawn into the compressor 21, and a suction temperature sensor 54 that detects the suction temperature, which is the temperature of the refrigerant drawn into the compressor 21.

[0027] Furthermore, the outdoor heat exchanger 24 is equipped with a heat exchanger temperature sensor 56 that detects the temperature of the refrigerant flowing inside the outdoor heat exchanger 24. In addition, an outdoor air temperature sensor 58 is provided that detects the temperature of the outside air flowing into the outdoor unit 2, that is, the outside air temperature in which the outdoor unit 2 is installed.

[0028] (Indoor Units) The three indoor units 8a to 8c are equipped with an indoor heat exchanger 81, an indoor expansion valve 82, and an indoor fan 83. Since the configuration of each indoor unit 8a to 8c is the same, the following explanation will only describe the configuration of indoor unit 8a, and the explanations for the other indoor units 8b and 8c will be omitted.

[0029] The indoor heat exchanger 81 has one end (one refrigerant inlet / outlet) connected to a liquid branch pipe 71 that branches off from the liquid pipe 31, and the other end (the other refrigerant inlet / outlet) connected to a gas branch pipe 72 that branches off from the gas pipe 32. The indoor heat exchanger 81 functions as an evaporator when the indoor unit 8a is in cooling operation, and as a condenser when the indoor unit 8a is in heating operation.

[0030] The indoor expansion valve 82 is located on the liquid branch pipe 71, with one port connected to the indoor heat exchanger 81 and the other port connected to the liquid pipe 31 via the liquid branch pipe 71. When the indoor heat exchanger 81 functions as an evaporator, the opening of the indoor expansion valve 82 is adjusted according to the required cooling capacity, and when the indoor heat exchanger 81 functions as a condenser, the opening of the indoor expansion valve 82 is adjusted according to the required heating capacity.

[0031] The indoor fan 83 is positioned near the indoor heat exchanger 81. The indoor fan 83 rotates using a fan motor (not shown) to draw indoor air into the indoor unit 8a, and after heat exchange between the refrigerant and the indoor air in the indoor heat exchanger 81, it supplies the heat-exchanged air to the room.

[0032] The indoor unit 8a is equipped with various sensors. A refrigerant temperature sensor 84 for detecting the temperature of the refrigerant is provided on the refrigerant piping at one end (one refrigerant inlet / outlet) of the indoor heat exchanger 81, and a refrigerant temperature sensor 85 for detecting the temperature of the refrigerant is provided on the refrigerant piping at the other end (the other refrigerant inlet / outlet) of the indoor heat exchanger 81. In addition, a room temperature sensor 86 for detecting the temperature of the indoor air flowing into the indoor unit 8a, i.e., the room temperature, is provided near the indoor air intake port (not shown) of the indoor unit 8a.

[0033] (Control device) The air conditioning system 100 includes a control device 90. The control device 90 is, for example, an outdoor unit control device installed in the outdoor unit 2, and is mounted on a control board housed in an electrical equipment box (not shown) of the outdoor unit 2.

[0034] Figure 2 is a block diagram showing the configuration of the control device 90. As shown in the figure, the control device 90 includes a CPU 91, a storage unit 92, a first communication unit 93, a sensor input unit 94, a rotation speed detection unit 95, and a second communication unit 96.

[0035] The memory unit 92 is a non-volatile memory such as flash memory, and stores the control program and control parameters of the outdoor unit 2, detected values ​​corresponding to detection signals from various sensors, the control status of the compressor 21 and outdoor fan 26, the rotation speed of the indoor fan 83 acquired via the first communication unit 93, and the control status of indoor units 8a to 8c, including the operating mode set by the user.

[0036] The first communication unit 93 is an interface for communication with the indoor units 8a to 8c. The second communication unit 96 is an interface for communication with the state management device 200, which will be described later. The sensor input unit 94 takes in the detection results from various sensors of the outdoor unit 2 and outputs them to the CPU 91. The rotation speed detection unit 95 detects the rotation speed of the motor of the compressor 21 and outputs it to the CPU 91. The rotation speed detection unit 95 may be configured to directly detect the rotation speed of the motor using an encoder or the like attached to the drive shaft of the motor, or it may be configured to detect the rotation speed of the motor from the drive current supplied to the motor. In the following description, the rotation speed of the compressor 21 refers to the rotation speed of the motor.

[0037] The CPU 91 is a control unit that controls the operation of each part of the outdoor unit 2, including the compressor 21, by executing a program stored in the memory unit 92. The program is installed in the control device 90, for example, via various recording media. Alternatively, the program may be installed via a status management device 200 or the internet.

[0038] The CPU 91 receives the detection results from each sensor of the outdoor unit 2 via the sensor input unit 94. Furthermore, the CPU 91 receives the control signals transmitted from the indoor units 8a to 8c via the communication unit 93. The control signals transmitted from the indoor units 8a to 8c include the required operating capacity (total heat load of indoor units 8a to 8c) requested by the indoor units 8a to 8c.

[0039] The CPU 91 controls the operation of the compressor 21, outdoor fan 26, and indoor fan 83 based on the acquired detection results and control signals, for example, by setting the indicated rotation speed, which is the rotation speed at which these devices are driven. The CPU 91 also controls the switching of the four-way valve 22 based on the acquired detection results and control signals. Furthermore, the CPU 91 controls the rotation speed of the compressor 21 and outdoor fan 26, and the opening degree of the outdoor expansion valve 25, based on the acquired detection results and control signals. The CPU 91 then transmits the detection results from each sensor of the outdoor unit 2, acquired via the sensor input unit 94, to the state management device 200, which will be described later, via the second communication unit 96.

[0040] [Operation of the Refrigerant Circuit] Next, the flow of refrigerant and the operation of each part in the refrigerant circuit 10 during air conditioning operation of the air conditioning system 100 in this embodiment will be explained with reference to Figure 1.

[0041] (Cooling Operation) When the air conditioning system 100 performs cooling operation, the four-way valve 22 of the outdoor unit 2 is switched to a first state (shown by a dashed line in Figure 1) in which port a and port b are in communication and port c and port d are in communication, thereby causing the outdoor heat exchanger 24 to function as a condenser.

[0042] The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 28 into the four-way valve 22. The refrigerant flowing out of the four-way valve 22 flows through the refrigerant pipe 37 into the outdoor heat exchanger 24, where it exchanges heat with the outside air and condenses. The refrigerant condensed in the outdoor heat exchanger 24 passes through the outdoor expansion valve 29 and flows into the liquid pipe 31 via the liquid side shut-off valve 45. The intermediate-pressure refrigerant that flows into the liquid pipe 31 is divided and flows into each indoor unit 8a to 8c by the liquid branch pipe 71.

[0043] The intermediate-pressure refrigerant flowing into each indoor unit 8a to 8c is reduced in pressure by the indoor expansion valve 82 to become low-pressure refrigerant, which then flows into the indoor heat exchanger 81. The low-pressure refrigerant flowing into the indoor heat exchanger 81 exchanges heat with the indoor air and evaporates, thereby cooling the room where the indoor units 8a to 8c are installed. At this time, the degree of refrigerant superheating at the outlet of the indoor heat exchanger 81, which is the evaporator, is determined from the refrigerant temperature detected by the refrigerant temperature sensors 84 and 85, and the opening of the indoor expansion valve 82 is adjusted accordingly.

[0044] The low-pressure refrigerant flowing out of the indoor heat exchanger 81 flows into the outdoor unit 2 through the gas branch pipe 72 and the gas pipe 32. The low-pressure refrigerant flowing into the outdoor unit 2 passes through the outdoor unit gas pipe 34, is sucked into the compressor 21 via the four-way valve 22 and the accumulator 27, and is compressed again.

[0045] (Heating Operation) When the air conditioner 100 performs a heating operation, the four-way valve 22 of the outdoor unit 2 is switched to a second state (indicated by the solid line in FIG. 1) in which port a communicates with port d and port b communicates with port c, thereby causing the outdoor heat exchanger 24 to function as an evaporator.

[0046] The high-pressure refrigerant discharged from the compressor 21 flows into the four-way valve 22 through the discharge pipe 28. The refrigerant flowing out of the four-way valve 22 flows through the outdoor unit gas pipe 34 and flows into the gas pipe 32 via the gas side stop valve 46. The high-pressure refrigerant flowing into the gas pipe 32 flows into the indoor units 8a to 8c through the gas branch pipe 72.

[0047] The high-pressure refrigerant flowing into each of the indoor units 8a to 8c flows into the indoor heat exchanger 81, exchanges heat with indoor air, and condenses. Thereby, the indoor air is warmed, and heating of the room where the indoor units 8a to 8c are installed is performed. The high-pressure refrigerant flowing out of the indoor heat exchanger 81 passes through the indoor expansion valve 82 and is decompressed. The opening degree of the indoor expansion valve 82 is determined according to the degree of supercooling of the refrigerant at the refrigerant outlet of the indoor heat exchanger 81. The degree of supercooling of the refrigerant is obtained, for example, by subtracting the refrigerant temperature at the refrigerant outlet of the indoor heat exchanger 81 detected by the refrigerant temperature sensor 84 from the high-pressure saturation temperature (corresponding to the condensation temperature in the indoor heat exchanger 81) calculated from the pressure detected by the high-pressure sensor 50 of the outdoor unit 2.

[0048] The intermediate-pressure refrigerant flowing out of each of the indoor units 8a to 8c flows into the liquid pipe 31 through the liquid branch pipe 71, and flows into the outdoor unit 2 via the shut-off valve 46. The intermediate-pressure refrigerant that has flowed into the outdoor unit 2 flows through the outdoor unit liquid pipe 35, passes through the outdoor expansion valve 29, is depressurized, and becomes low-pressure refrigerant. The opening degree of the outdoor expansion valve 40 is determined according to the degree of superheat of the refrigerant at the refrigerant outlet of the outdoor heat exchanger 24. The degree of superheat of the refrigerant is obtained, for example, by subtracting the low-pressure saturation temperature (corresponding to the evaporation temperature in the outdoor heat exchanger) calculated from the pressure detected by the low-pressure sensor 51 of the outdoor unit 2 from the refrigerant temperature in the outdoor heat exchanger 24 detected by the heat exchange temperature sensor 56.

[0049] The low-pressure refrigerant depressurized by the outdoor expansion valve 29 flows into the outdoor heat exchanger 24, exchanges heat with outdoor air, and evaporates. Then, the low-pressure refrigerant flowing out of the outdoor heat exchanger 24 is sucked into the compressor 21 via the four-way valve 22 and the accumulator 27, and is compressed again.

[0050] [State Management Device] The state management device 200 is an information processing device that manages the state of the outdoor unit 2, for example, whether there is an abnormality in the four-way valve 22, and is installed in a management room or the like that remotely manages the air conditioner 100. The state management device 200 is connected to the second communication unit 96 of the air conditioner 100 via a network such as the Internet or a wide area communication network. In the present embodiment, the state management device 200 determines whether there is an abnormality in the four-way valve 22 based on the detection results from various sensors of the outdoor unit 2 acquired by the sensor input unit 94.

[0051] FIG. 3 is a block diagram showing the configuration of the state management device 200. The state management device 200 includes hardware necessary for a computer, such as a processor such as a CPU, a memory such as a ROM and a RAM, and a storage device such as an HDD.

[0052] A database 201 is connected to the status management device 200. The database 201 functions as a storage unit and stores various information received from the air conditioning system 100 (including data acquired by the sensor input unit 94, data detected by the rotation speed detection unit 95, and the processing history of the CPU 91). The status management device 200 uses this data to manage the status of the outdoor unit 2. The database 201 stores parameters necessary for the calculation of the estimated intake temperature, which will be described later in the status management device 200, such as intake temperature, discharge temperature, and outside air temperature, in a time-series manner.

[0053] The state management device 200 includes an acquisition unit 210 and a control unit 220 as functional blocks of the CPU. Here, we will describe the part related to the processing necessary for calculating the estimated intake temperature.

[0054] (Acquisition Unit) The acquisition unit 210 receives data acquired from the air conditioner 100 at the sensor input unit 94 at predetermined intervals (for example, every 30 minutes) and stores it in the database 201. The predetermined interval is set to be longer than, for example, the data acquisition cycle (several seconds to several minutes) at the sensor input unit 94. The acquisition unit 210 receives all the data acquired by the sensor input unit 94 for the predetermined interval. The data acquisition cycle at the sensor input unit 94 may be the same for each sensor or may differ for each sensor.

[0055] (Control Unit) The control unit 220 includes a determination unit 221, a signal generation unit 222, and a timing unit 223.

[0056] When the compressor 21 stops, the determination unit 221 outputs an estimated intake temperature, which is an estimated value of the intake temperature immediately after the compressor 21 stops. By comparing this estimated intake temperature with the intake temperature obtained immediately after the compressor 21 stops (hereinafter sometimes referred to as the measured intake temperature), the determination unit 221 determines whether or not there is an abnormality in the four-way valve 22. As will be described later, information regarding the estimated intake temperature is generated using the discharge temperature obtained immediately before and immediately after the compressor 21 stops, the intake temperature obtained immediately before the compressor 21 stops, and the ambient temperature obtained immediately before or immediately after the compressor 21 stops.

[0057] When the signal generation unit 222 determines, based on the determination result from the determination unit 221, that there is an abnormality in the four-way valve 22, it generates an alarm signal to notify the operator in the control room where the air conditioning unit 100 or the condition management device 200 is installed. This prompts the operator to perform necessary maintenance on the air conditioning unit 100.

[0058] The timing unit 223 calculates the compressor stop time, which will be described later.

[0059] [Abnormalities in the four-way valve] Figure 4 is a schematic cross-sectional view showing one example of the configuration of the four-way valve 22. In the figure, (A) shows the state during cooling operation, and (B) shows the state during heating operation.

[0060] The four-way valve 22 has a valve body 150 and a pilot solenoid valve 160 for switching the connection state. In the figure, "LP" indicates the pressure of the refrigerant drawn into the compressor 21, and "HP" indicates the pressure of the refrigerant discharged from the compressor 21.

[0061] The valve body 150 has a first connection port 151 (corresponding to port c in Figure 1), a second connection port 152 (corresponding to port d in the same), a third connection port 153 (corresponding to port b in the same), a fourth connection port 154 (corresponding to port a in the same), a first chamber 155, a second chamber 156, and a valve element 157.

[0062] The valve body 157 is positioned inside the valve body 150 so as to separate the space on the side of the first connection port 151 from the space on the side of the fourth connection port 54 between the first chamber 155 and the second chamber 156. The valve body 157 slides in response to the pressure acting on the first chamber 155 and the second chamber 156.

[0063] Specifically, when low pressure acts on the first chamber 155 and high pressure acts on the second chamber 156, the valve body 157 slides toward the first chamber 155 side, resulting in a first state (Figure 4(A)) where the fourth connection port 154 and the third connection port 153 communicate, and the second connection port 152 and the first connection port 151 communicate. Furthermore, when high pressure acts on the first chamber 155 and low pressure acts on the second chamber 156, the valve body 157 slides toward the second chamber 156 side, resulting in a second state (Figure 4(B)) where the fourth connection port 154 and the second connection port 152 communicate, and the third connection port 153 and the first connection port 151 communicate.

[0064] The first chamber 155 is provided with a first communication section 155a that is connected to a first pilot pipe 172 extending from the pilot solenoid valve 160. The second chamber 156 is provided with a second communication section 156a that is connected to a second pilot pipe 173 extending from the pilot solenoid valve 160.

[0065] The pilot solenoid valve 160 has a high-voltage intake port 164, a low-voltage intake port 161, a first operating port 162, and a second operating port 163.

[0066] The high-voltage sourcing port 164 is connected to the high-voltage sourcing section 154a via the high-voltage sourcing pipe 174. The high-voltage sourcing section 154a is located in the internal space of the valve body 150 where the fourth connection port 154 is located. The low-voltage sourcing port 161 is connected to the low-voltage sourcing section 151a via the low-voltage sourcing pipe 171. The low-voltage sourcing section 151a is located in the first connection port 151. The first operating port 162 is connected to the first communication section 155a via the first pilot pipe 172. The second operating port 163 is connected to the second communication section 156a via the second pilot pipe 173.

[0067] When the pilot solenoid valve 160 switches the four-way valve 22 from the second state to the first state, it applies the refrigerant pressure taken from the high-pressure intake port 164 to the second operating port 163, while applying the refrigerant pressure taken from the low-pressure intake port 161 to the first operating port 162, thereby introducing refrigerant pressure into the second chamber 156 and sliding the valve body 157 toward the first chamber 155 (Figure 4(A)).

[0068] When the pilot solenoid valve 160 switches the four-way valve 22 from the first state to the second state, it applies the refrigerant pressure taken from the high-pressure intake port 64 to the first operating port 62, while applying the refrigerant pressure taken from the low-pressure intake port 61 to the second operating port 63, thereby introducing refrigerant pressure into the first chamber 155 and sliding the valve body 157 toward the second chamber 156 (Figure 4(B)).

[0069] Switching between the first state and the second state is performed by supplying or de-energizing the pilot solenoid valve 160. When the four-way valve 22 is functioning normally, the valve body 157 will be in either the first state or the second state.

[0070] As explained above, the valve body 157 is positioned according to either cooling or heating operation. However, if the position of the valve body 157 shifts, for example, as shown in Figure 4(C), the valve body 157 may be positioned between the position in the first state and the position in the second state, which may result in an inappropriate connection state of the refrigerant flow path. If the position of the valve body 157 is as shown in Figure 4(C), most of the refrigerant discharged from the compressor 21 will pass through the fourth connection port 154 of the valve body 150, then through the gap between the second connection port 152 and the valve body 157, through the first connection port 151, and then through the refrigerant piping 36, accumulator 27, and suction piping 42, and be sucked back into the compressor 21.

[0071] The four-way valve 22 is designed to switch between directing the discharged refrigerant to the indoor heat exchanger 24 (during cooling) or directing it to the indoor units 8a to 8c (during heating). Therefore, the valve body never takes an intermediate position between the two. If the four-way valve 22 malfunctions and the switching is not performed properly, some of the high-temperature, high-pressure gaseous refrigerant in the discharge pipe 28 will flow directly into the suction pipe 42, preventing the air conditioning system from performing at its intended capacity. Since the air conditioning system does not have equipment to directly monitor the switching status of the four-way valve 22, it is necessary to use an already installed sensor to detect a malfunction (abnormality) in the four-way valve 22.

[0072] However, in the method described in Patent Document 1, which determines whether there is a malfunction in the four-way valve (an abnormality in the position of the valve body of the four-way valve) based on the temperature difference between the temperature of the refrigerant discharged from the compressor and the temperature of the refrigerant drawn into the compressor when the temperature difference between the temperature of the refrigerant flowing through the indoor heat exchanger and the room temperature is below a predetermined value, as mentioned above, there is a risk that the determination process will be performed even though a malfunction in the four-way valve is not actually necessary, because the temperature difference between the temperature of the refrigerant flowing through the indoor heat exchanger and the room temperature may fall below a predetermined value depending on the operating state of the indoor unit, such as the size of the air conditioning load of the indoor unit or when the indoor unit's thermostat is OFF, due to reasons other than a malfunction in the four-way valve. As a result, this leads to an increase in the load on the control unit due to unnecessary determination processing, and also results in disadvantages such as misidentification of a malfunction in the four-way valve when the discharge temperature and intake temperature are close for reasons other than a malfunction in the four-way valve.

[0073] Furthermore, when the compressor's operating capacity is reduced, the temperature of the refrigerant discharged from the compressor and the temperature of the refrigerant drawn into the compressor may become close. Therefore, if the above predetermined value is not set with sufficient margin, there is a risk that the four-way valve may be misidentified as malfunctioning even though it is functioning normally. In addition, if the compressor malfunctions or the refrigerant charge amount is not appropriate, the above temperature difference may also become close, which may lead to a misidentification of a malfunction other than the four-way valve as a malfunction of the four-way valve.

[0074] Furthermore, Patent Document 1 does not provide specific details on which indoor unit to use to determine the temperature difference between the refrigerant temperature flowing through the indoor heat exchanger and the room temperature in the case of an air conditioning system in which multiple indoor units are connected to one outdoor unit, or how to handle the temperature difference in each indoor unit. Therefore, in an air conditioning system equipped with multiple indoor units, it may not be possible to accurately determine whether or not a four-way valve malfunction is necessary. Moreover, in a method of determining a four-way valve malfunction using the temperature difference between the discharge temperature and the intake temperature, if the displacement of the valve body of the four-way valve is slight, the amount of refrigerant discharged from the compressor that flows to the intake side of the compressor is also small. Therefore, even if the four-way valve is malfunctioning, it may not be possible to determine that the four-way valve is malfunctioning because the difference between the temperature of the refrigerant discharged from the compressor and the temperature of the refrigerant drawn into the compressor does not fall below a predetermined value.

[0075] To resolve these issues, the state management device 200 of this embodiment uses the detection data from sensors installed on the outdoor unit 2, namely the discharge temperature sensor 53, the intake temperature sensor 54, and the outside air temperature sensor 58, to determine whether or not there is an abnormality in the four-way valve 22. This allows for accurate determination of whether or not there is an abnormality in the four-way valve 22 without being affected by the operating state of the indoor unit 3. The details of the control unit 220 in the state management device 200 will be described below.

[0076] [Details of the Condition Management Device] In this embodiment, when the four-way valve 22 malfunctions, the high-temperature refrigerant flowing through the discharge pipe 28 flows into the suction pipe 42, causing the suction temperature to rise. The discharge temperature and ambient temperature are used to estimate the suction temperature immediately after the compressor 21 stops operating. If the measured suction temperature is higher than the estimated suction temperature by a certain amount or more, it is determined that the four-way valve is malfunctioning. The reason for using the estimated suction temperature immediately after the compressor 21 stops operating to determine whether there is a malfunction is that the fluctuation in suction temperature due to the outflow of refrigerant from the discharge pipe 28 to the suction pipe 42 becomes more pronounced immediately after the compressor 21 stops operating than when the compressor 21 is operating, making it easier to determine if the four-way valve 22 is malfunctioning.

[0077] As described above, when the compressor 21 stops, the control unit 220 of the state management device 200 outputs an estimated intake temperature, which is an estimated value of the intake temperature immediately after the compressor 21 stops, using the discharge temperature acquired immediately before and immediately after the compressor 21 stops, the intake temperature acquired immediately before the compressor 21 stops, and the ambient temperature acquired immediately before or immediately after the compressor stops. By comparing the measured intake temperature acquired immediately after the compressor 21 stops with the estimated intake temperature, the control unit 220 determines whether or not there is an abnormality in the four-way valve 22.

[0078] Furthermore, the timing for detecting the outside air temperature was set to "immediately before or immediately after the compressor 21 stops" because it is not considered that the outside air temperature would change significantly immediately before and immediately after the compressor 21 stops. Therefore, it was determined that the outside air temperature could be detected at either the time immediately before or immediately after the compressor 21 stops.

[0079] Note that "immediately before the compressor 21 stops" refers to the timing of acquiring the detection value of each sensor immediately preceding the compressor 21's stop time. "Immediately after the compressor 21 stops" refers to the timing of acquiring the detection value of each sensor for the first time after the compressor 21 stops. The compressor 21's stop time may be determined based on the time when the rotation speed detection unit 95 detects a signal corresponding to zero rotation speed, or the time when the control unit 90 of the outdoor unit 2 outputs a control command to stop operation to the compressor 21 may be extracted from the CPU 91's processing history.

[0080] In this case, the timing of detecting the stoppage of the compressor 21 may differ from the timing of acquiring the intake temperature, discharge temperature, and ambient temperature. If the estimated intake temperature is estimated using the detected discharge temperature value acquired after the compressor 21 has stopped, the discharge temperature will start to decrease immediately after the compressor 21 stops, resulting in the detected discharge temperature being lower than the discharge temperature immediately after the compressor 21 stops. Furthermore, using this discharge temperature to estimate the intake temperature may reduce accuracy.

[0081] Therefore, in this embodiment, the control unit 220 (timing unit 223) calculates the compressor stop time, which is the time from when the compressor 21 stops until the discharge temperature is first acquired after the compressor 21 stops. The control unit then adds the compressor stop time to each of the estimation parameters (discharge temperature acquired immediately before and immediately after the compressor 21 stops, suction temperature acquired immediately before the compressor 21 stops, and ambient temperature acquired immediately before or immediately after the compressor stops) and outputs the estimated suction temperature. More specifically, the discharge temperature, which begins to decrease immediately after the compressor 21 stops, is corrected using the compressor stop time and used as the estimated discharge temperature immediately after the compressor 21 stops. This suppresses a decrease in estimation accuracy caused by the time difference between the compressor 21 stopping timing and the timing of discharge temperature acquisition.

[0082] The method for calculating the estimated intake temperature in the control unit 90 is not particularly limited. In this embodiment, a machine learning model (trained model) that has been pre-trained using training data including (1a) the discharge temperature immediately before the compressor 21 stops, (2a) the discharge temperature immediately after the compressor 21 stops, (3a) the intake temperature immediately before the compressor 21 stops, (4a) the ambient temperature, and (5a) the compressor stop time is used.

[0083] For example, the above machine learning model corresponds to a function that takes the detected values ​​(1a) to (5a) as arguments and uses them to return an estimated value of the intake temperature immediately after the compressor 21 stops. In other words, in this embodiment, a learning model that estimates the intake temperature immediately after the compressor stops is constructed by training it with a large number of relationships between the intake temperature and discharge temperature immediately before and immediately after the compressor 21 stops under various operating environments.

[0084] The learning algorithm is not particularly limited; for example, ensemble learning models combining multiple linear regression, neural networks, decision trees, support vector machines, or a combination thereof can be applied.

[0085] (Method for generating a trained model) Figure 5 is a flowchart showing an example of the procedure for generating a trained model that estimates the intake temperature immediately after the compressor 21 is stopped. The trained model is generated in advance before the air conditioning system 100 is installed (before operation starts). This trained model may be generated by the state management device 200, or by an information processing device other than the state management device 200, such as the control device 90 of the air conditioning system 100. Here, an example of generating the trained model using the control unit 220 of the state management device 200 will be described.

[0086] The control unit 220 extracts data from the time-series data of each sensor of the outdoor unit 2 of the air conditioner 100 stored in the database 201, showing the data before and after the compressor 21 stops operating (ST101).

[0087] The above data refers to data acquired in advance from the outdoor unit 2 of the air conditioning system 100 at the sensor input unit 94 of the control device 90, and specifically refers to the data set included in the acquisition timing at the sensor input unit 94 corresponding to before and after the compressor 21 stops operating. These data sets are prepared in advance as data sets for generating a learning model, and for example, data acquired during pre-shipment test runs or simulations of the air conditioning system to be managed, or actual measured values ​​during operation acquired via an external server from other air conditioning systems of the same model that are already installed, are used. All of these data sets are detected values ​​when the four-way valve 22 is operating normally.

[0088] Next, the control unit 220 deletes data from the acquired data set in which the continuous operating time of the compressor 21 is less than 30 minutes (ST102). Since an operating state with a continuous operating time of less than 30 minutes can be considered as an intermittent operating state of the compressor 21, from the viewpoint of improving estimation accuracy, only data acquired in a relatively stable operating state with a continuous operating time of 30 minutes or more is used here. Note that the threshold of 30 minutes for operating time is merely an example and can be changed according to the specifications of the air conditioning system 100 being tested.

[0089] The operating time of the compressor 21 refers to the time from the time the compressor 21 is started until the time the compressor 21 is stopped. The start time is the time when the control device 90 outputs a control command to start operation to the compressor 21, and the stop time is the time when the control device 90 outputs a control command to stop operation to the compressor 21.

[0090] Next, the control unit 220 extracts feature quantities to be used for estimation from the remaining data (ST103). These feature quantities include (1a) the discharge temperature immediately before the compressor 21 stops, (2a) the discharge temperature immediately after the compressor 21 stops, (3a) the suction temperature immediately before the compressor 21 stops, (4a) the ambient temperature, and (5a) the compressor stop time. In this embodiment, the ambient temperature used is the ambient temperature detected immediately after the compressor 21 stops.

[0091] Next, the control unit 220 divides the data (1a) to (5a) extracted as features into training data and validation data (ST104). The training data is used as training data to generate a machine learning model that outputs an estimated intake temperature. On the other hand, the validation data is used, as will be described later, as data to determine the threshold applied when determining whether the estimated intake temperature output using the generated machine learning model is an abnormality of the four-way valve 22.

[0092] The splitting method is not particularly limited, and in this embodiment, the data is randomly split into training data and validation data. The ratio of the training data to the validation data is, for example, 4:1 in terms of the quantity ratio of each data.

[0093] Next, the control unit 220 executes a learning algorithm using the training model (ST105) and saves the generated trained model (ST106).

[0094] Next, the control unit 220 applies the trained model to the verification data to obtain the estimated intake temperature, which is an estimated value of the intake temperature immediately after the compressor 21 stops (ST107), and calculates the difference between the estimated intake temperature and the measured intake temperature (measured intake temperature) in the verification data (ST108).

[0095] Next, the control unit 220 uses verification data to set a threshold value that serves as the criterion for determining whether or not there is an abnormality in the four-way valve 22. In this embodiment, as described above, the threshold value for abnormality determination is determined based on the mean value (μ) and standard deviation (σ) of the difference between the intake temperature immediately after the compressor 21 is stopped (measured intake temperature) used as training data and the estimated intake temperature obtained using the generated trained model. Here, for example, the threshold value is set so that if the difference between the measured intake temperature and the estimated intake temperature is within the range of 2 sigma (μ ± 2σ) (-2σ to +2σ, 95.4%), the four-way valve 22 is determined to be normal (ST109). Note that (μ ± 2σ) refers to a predetermined range centered on the mean value (μ), with the upper limit being (μ + 2σ) and the lower limit being (μ - 2σ).

[0096] As described above, a trained model for calculating the estimated intake temperature is generated. The threshold for abnormality detection is not limited to 2 sigma; depending on the number of measured data used as verification data, the specifications of the air conditioning system 100, or the operating environment, the threshold can also be set to 1 sigma (μ + σ, 68.3%) or 3 sigma (μ + 3 σ, 99.7%).

[0097] The above-mentioned trained models may be generated individually for each installation environment of the air conditioning system 100 (region, piping length, refrigerant charge amount, etc.). This allows for the detection of abnormalities in the four-way valve using a trained model that is suitable for the specifications of the air conditioning system (outdoor unit) to be managed.

[0098] (Procedure for determining abnormalities in a four-way valve) Figure 6 is a flowchart showing an example of the procedure for determining abnormalities in a four-way valve 22 that is performed in the control unit 220 of the state management device 200.

[0099] The control unit 220 extracts data from the time-series data of each sensor of the outdoor unit 2 of the air conditioner 100, which is stored in the database 201 via the acquisition unit 210, for the period before and after the compressor 21 stops operating (ST201). The above data refers to the data acquired by the sensor input unit 94 transmitted from the control device 90 of the outdoor unit 2 of the air conditioner 100 that is currently in operation, and refers to the data group included in the acquisition timing of the sensor input unit 94 that corresponds to the period before and after the compressor 21 stops operating.

[0100] Next, the control unit 220 deletes data from the acquired data set in which the continuous operating time of the compressor 21 is less than 30 minutes (ST202). Since an operating state with a continuous operating time of less than 30 minutes can be considered as an intermittent operating state of the compressor 21, from the viewpoint of improving estimation accuracy, only data acquired in a relatively stable operating state with a continuous operating time of 30 minutes or more is used here. Note that the operating time threshold of 30 minutes is merely an example and can be changed according to the specifications of the air conditioning system 100 being tested.

[0101] Next, the control unit 220 extracts feature quantities to be used for estimation from the remaining data (ST203). These feature quantities include (1b) the discharge temperature immediately before the compressor 21 stops, (2b) the discharge temperature immediately after the compressor 21 stops, (3b) the suction temperature immediately before the compressor 21 stops, (4b) the ambient temperature, and (5b) the compressor stop time. In this embodiment, the ambient temperature used is the ambient temperature detected immediately after the compressor 21 stops.

[0102] Next, the control unit 220 inputs the actual detected values ​​(1b) to (5b) described above as arguments to the machine learning model described above, and outputs the estimated intake temperature, which is an estimated value of the intake temperature immediately after the compressor 21 stops (ST204). It also calculates the difference between the intake temperature obtained immediately after the compressor 21 stops (measured intake temperature) and the estimated intake temperature (ST205).

[0103] Next, the control unit 220 calculates the average value of the above difference, for example, over the past day (ST206). The average value of the above difference over a day is calculated from the number of times the compressor 21 stops during a day of operation and the value of the above difference calculated at the timing of each stop. It is not limited to one day, of course, but may be half a day or two days or more. Alternatively, instead of on a daily basis, the average value when the number of times the compressor 21 stops reaches a predetermined number (for example, 10 times) (hereinafter also referred to as the measured average value) may be calculated and used as the basis.

[0104] Next, the control unit 220 determines whether the measured average value calculated in ST206 is within the threshold range (2σ of the difference) (ST207). If the above average value is within the threshold range ((μ-2σ) or greater and (μ+2σ) or less), the control unit 220 determines that the four-way valve 22 is normal (ST208). If it is outside the threshold range (less than (μ-2σ) and greater than (μ+2σ)), the control unit 220 determines that the four-way valve 22 is abnormal (ST209).

[0105] By comparing the average value with a threshold in this way, it is possible to prevent the four-way valve 22 from being judged as abnormal due to the occurrence of accidental abnormal data, and it is also possible to estimate the lifespan of the four-way valve 22 by understanding the trend of the average value (for example, if the average value is approaching the threshold over time, it can be estimated that its lifespan is nearing its end).

[0106] When the control unit 220 determines that the four-way valve 22 is malfunctioning, it generates an alarm signal to notify the operator in the control room where the air conditioning unit 100 or the condition management device 200 is installed. This prompts the operator to perform necessary maintenance on the air conditioning unit 100.

[0107] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the embodiments described above and can be modified in various ways.

[0108] For example, in the above embodiment, the state management device 200 was configured as a separate device from the air conditioning system 100, but it is not limited to this, and may be configured as part of the air conditioning system 100 (for example, as part of the control device 90). In this case, the control device 90 generates a learning model for estimating the estimated intake temperature before the air conditioning system is installed, and after the air conditioning system is installed, it outputs the estimated intake temperature using the generated learning model and determines whether or not there is an abnormality in the four-way valve 22. The program for generating the learning model and the training data may be stored in the storage unit 92 in advance, or they may be downloaded from a server such as the state management device 200.

[0109] Furthermore, although the above embodiments have described an air conditioning system 100 in which a plurality of indoor units 8a to 8c are connected to a single outdoor unit 2 as an example, the present invention is also applicable to air conditioning systems with one indoor unit or two or more outdoor units 2.

[0110] Furthermore, in the above embodiments, a four-way valve 22 was used as an example to describe the object to be determined for the presence or absence of abnormality, but the invention is not limited to this, and other flow path switching valves may also be used.

[0111] Furthermore, in the above embodiments, a pre-trained machine learning model was used to determine whether or not there was an abnormality in the four-way valve. However, the measured data (1b) to (5b) used to calculate the estimated intake temperature may be used as training data to reconstruct the machine learning model in operation or update the threshold value which is the judgment criterion.

[0112] 1...Air conditioning system 2...Outdoor unit 8a, 8b, 8c...Indoor unit 10...Refrigerant circuit 21...Compressor 22...Four-way valve 24...Outdoor heat exchanger 29...Outdoor expansion valve 90...Control device 100...Air conditioning device 200...Condition management device 220...Control unit

Claims

1. A condition management device for managing the condition of an outdoor unit of an air conditioning system having a compressor, an outdoor heat exchanger, and a flow path switching valve, comprising: an acquisition unit that acquires information relating to the operating state of the compressor, a discharge temperature which is a detected value of the temperature of the refrigerant on the refrigerant discharge side of the compressor, an intake temperature which is a detected value of the temperature of the refrigerant on the refrigerant suction side of the compressor, and an outside air temperature which is a detected value of the temperature of the outside air where the outdoor unit is installed; and a control unit that, when the compressor stops, uses the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops to output an estimated intake temperature which is an estimated value of the intake temperature immediately after the compressor stops, and determines whether or not there is an abnormality in the flow path switching valve by comparing the intake temperature acquired immediately after the compressor stops with the estimated intake temperature.

2. A state management device according to claim 1, wherein the acquisition unit acquires the discharge temperature, the intake temperature, and the ambient temperature at predetermined intervals, and the control unit calculates the compressor stop time, which is the time from when the compressor stops until the discharge temperature is first acquired after the compressor stops, and outputs the estimated intake temperature based on the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, the ambient temperature acquired immediately before or immediately after the compressor stops, and the compressor stop time.

3. A state management device according to claim 2, wherein the control unit outputs the estimated intake temperature using a machine learning model trained with training data including the discharge temperature acquired immediately before and immediately after the compressor is stopped, the intake temperature acquired immediately before the compressor is stopped, the ambient temperature acquired immediately before or immediately after the compressor is stopped, and the compressor stop time.

4. A state management device according to claim 3, wherein the control unit has a threshold for abnormality determination set based on the average value and standard deviation of the temperature difference between the intake temperature immediately after the compressor stops and the estimated intake temperature, using verification data including the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, the ambient temperature acquired immediately before or immediately after the compressor stops, and the compressor stop time.

5. A state management device according to claim 4, wherein the control unit determines that the flow path switching valve is abnormal when the calculated estimated intake temperature exceeds an upper limit and a lower limit within a predetermined range centered on the average value.

6. A state management device according to claim 4, wherein the control unit updates the threshold value based on the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops, while the air conditioning system is in operation.

7. A state management device according to any one of claims 1 to 6, wherein the flow path switching valve is a four-way valve.

8. A state management method for managing the state of an outdoor unit of an air conditioning system having a compressor, an outdoor heat exchanger, and a flow path switching valve, the method comprising: acquiring information regarding the operating state of the compressor, a discharge temperature which is a detected value of the temperature of the refrigerant on the refrigerant discharge side of the compressor, an intake temperature which is a detected value of the temperature of the refrigerant on the refrigerant suction side of the compressor, and an outside air temperature which is a detected value of the temperature of the outside air where the outdoor unit is installed; outputting an estimated intake temperature which is an estimated value of the intake temperature immediately after the compressor stops, using the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops; and determining whether or not there is an abnormality in the flow path switching valve by comparing the estimated intake temperature with the intake temperature acquired immediately after the compressor stops.

9. An air conditioning system comprising: an outdoor unit having a compressor, an outdoor heat exchanger, and a flow path switching valve; an indoor unit having an indoor heat exchanger; and a refrigerant circuit including refrigerant piping connecting the outdoor unit and the indoor unit; and a state management device for managing the state of the outdoor unit, wherein the state management device includes: an acquisition unit that acquires information relating to the operating state of the compressor, a discharge temperature which is a detected value of the temperature of the refrigerant on the refrigerant discharge side of the compressor, an intake temperature which is a detected value of the temperature of the refrigerant on the refrigerant suction side of the compressor, and an outside air temperature which is a detected value of the outdoor air temperature where the outdoor unit is installed; an air conditioning system comprising: an acquisition unit that acquires information relating to the operating state of the compressor, a discharge temperature which is a detected value of the temperature of the refrigerant on the refrigerant discharge side of the compressor, and an outside air temperature which is a detected value of the temperature of the outdoor air where the outdoor unit is installed; and when the compressor stops, an estimated intake temperature which is an estimated value of the intake temperature immediately after the compressor stops, using the discharge temperature acquired immediately before and immediately after the compressor stops, the intake temperature acquired immediately before the compressor stops, and the outside air temperature acquired immediately before or immediately after the compressor stops; and a control unit that determines whether or not there is an abnormality in the flow path switching valve by comparing the estimated intake temperature with the intake temperature acquired immediately after the compressor stops.

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