Air conditioner

Abstract

In a refrigerant circuit in which an indoor unit is connected to an outdoor unit by a refrigerant pipe, a predetermined amount of refrigerant is filled, the outdoor unit has a compressor, an outdoor heat exchanger, and an expansion valve, and the indoor unit has an indoor heat exchanger. The air conditioner has a calculation model that calculates an amount of refrigerant remaining in the refrigerant circuit using at least a rotational speed of the compressor, a refrigerant discharge temperature of the compressor, a heat exchanger temperature, an opening degree of the expansion valve, and an outside air temperature, which are amounts indicating an operating state at the time of operation. The indoor heat exchanger has a sensor for detecting a temperature of refrigerant flowing through an indoor heat exchanger intermediate portion that connects a first indoor heat exchanger port portion and a second indoor heat exchanger port portion. The outdoor heat exchanger has an outdoor heat exchanger intermediate portion that connects a first outdoor heat exchanger port portion and a second outdoor heat exchanger port portion, and a sensor provided in the second outdoor heat exchanger port portion for detecting a temperature of refrigerant flowing from an outdoor heat exchanger outlet of the second outdoor heat exchanger port portion at the time of refrigeration operation. The present invention provides an air conditioner that can calculate the amount of refrigerant remaining even when only limited sensors are provided.

Description

Technical Field

[0001] This invention relates to air conditioners. Background Technology

[0002] An air conditioner is known to use operating state quantities detectable in the refrigerant circuit to determine the refrigerant dosage. In Patent Document 1, for example, the refrigerant dosage is determined using the subcooling at the condenser outlet when the superheat and evaporator pressure of the refrigerant circuit during the refrigeration cycle are set to preset values ​​(hereinafter referred to as the default state).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-23072 Summary of the Invention

[0004] In air conditioning systems, sensors are needed to measure operating status parameters such as subcooling when determining the amount of refrigerant. For example, commercial air conditioning systems located in large buildings such as commercial facilities or office buildings, where one outdoor unit connects to multiple indoor units, are equipped with multiple sensors to control the multiple indoor units. Therefore, the operating status parameters can be calculated using the values ​​from each sensor. For example, for each indoor heat exchanger and each outdoor heat exchanger, the subcooling can be calculated using the sensor values ​​from the temperature sensors at the heat exchange points and heat exchange outlets.

[0005] However, for example, in residential air conditioners with one outdoor unit connected to one indoor unit, primarily installed in homes, from a cost-saving perspective, the number of sensors installed is limited to the minimum required for the air conditioner's operation. For instance, in some residential air conditioners, there are only two temperature sensors in both the indoor and outdoor heat exchangers: one to detect the refrigerant temperature in the middle of the indoor heat exchanger and the other to detect the refrigerant temperature at the refrigerant outlet of the outdoor heat exchanger. In this case, the subcooling at the condenser outlet cannot be calculated, and therefore the refrigerant dosage cannot be determined using the subcooling at the condenser outlet.

[0006] Therefore, a method is needed to enable air conditioners with only a limited number of sensors to calculate the amount of refrigerant.

[0007] The present invention was made in view of the above-mentioned problems, and its object is to provide an air conditioner that can calculate the amount of refrigerant remaining in the refrigerant circuit (hereinafter referred to as the residual refrigerant amount) even with only a limited number of sensors.

[0008] An air conditioner has a refrigerant circuit formed by connecting an indoor unit to an outdoor unit via refrigerant piping. The outdoor unit has a compressor, an outdoor heat exchanger, and an expansion valve. The indoor unit has an indoor heat exchanger. The refrigerant circuit is filled with a preset amount of refrigerant. The air conditioner has a residual refrigerant dosage estimation model, which uses at least the compressor speed, the compressor refrigerant discharge temperature, the heat exchanger temperature, the opening degree of the expansion valve, and the outside air temperature, representing the operating state of the air conditioner, to estimate the residual refrigerant dosage in the refrigerant circuit. The indoor heat exchanger has: a first indoor heat exchange port for refrigerant flow; a second indoor heat exchange port for refrigerant flow; an indoor heat exchange intermediate section connecting the first and second indoor heat exchange ports; and an indoor heat exchange intermediate sensor located in the indoor heat exchange intermediate section for detecting the temperature of the refrigerant flowing through the indoor heat exchange intermediate section. The outdoor heat exchanger includes: a first outdoor heat exchange port for the refrigerant to flow through; a second outdoor heat exchange port for the refrigerant to flow through; an outdoor heat exchange intermediate section connecting the first outdoor heat exchange port and the second outdoor heat exchange port; and an outdoor heat exchange outlet sensor located at the second outdoor heat exchange port for detecting the temperature of the refrigerant flowing through the outdoor heat exchange outlet of the second outdoor heat exchange port during refrigeration operation.

[0009] On the one hand, it is possible to use a limited number of sensors to estimate the remaining cooling dose. Attached Figure Description

[0010] Figure 1 This is an explanatory diagram illustrating an example of an air conditioner according to this embodiment.

[0011] Figure 2 This is an illustrative diagram showing an example of an outdoor unit and an indoor unit.

[0012] Figure 3 This is a block diagram illustrating an example of the control circuitry for an indoor unit.

[0013] Figure 4 It is a Morrill diagram that represents the state of refrigerant changes in an air conditioner.

[0014] Figure 5 This is a flowchart illustrating an example of the processing actions of a control circuit involved in calculation processing.

[0015] Figure 6 This is an illustrative diagram representing an example of training data used in multivariate regression analysis.

[0016] Figure 7This is an illustrative diagram representing an example of training data used to generate a predictive model that classifies residual cooling dose as normal or abnormal.

[0017] Figure 8 This is an explanatory diagram illustrating an example of the air conditioning system of Embodiment 2. Detailed Implementation

[0018] Hereinafter, embodiments of the air conditioner, etc., disclosed in this application will be described in detail based on the accompanying drawings. Furthermore, the disclosed technology is not limited to these embodiments. Additionally, the embodiments shown below can be appropriately modified without causing contradiction.

[0019] Example 1

[0020] Air conditioner structure

[0021] Figure 1 This is an explanatory diagram showing an example of the air conditioner 1 in this embodiment. Figure 1 The air conditioner 1 shown is, for example, a household air conditioner, which includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 is connected to the indoor unit 3 via a liquid pipe 4 and a gas pipe 5. Furthermore, by connecting the outdoor unit 2 and the indoor unit 3 with refrigerant piping such as the liquid pipe 4 and the gas pipe 5, a refrigerant circuit 6 of the air conditioner 1 is formed.

[0022] outdoor unit structure

[0023] Figure 2 This is an explanatory diagram showing an example of outdoor unit 2 and indoor unit 3. Outdoor unit 2 includes: compressor 11, four-way valve 12, outdoor heat exchanger 13, expansion valve 14, liquid receiver 15, outdoor unit fan 16, and control circuit 17. Using the compressor 11, four-way valve 12, outdoor heat exchanger 13, expansion valve 14, and liquid receiver 15, they are interconnected by various refrigerant piping as described in detail below, thereby forming an outdoor refrigerant circuit as part of refrigerant circuit 6.

[0024] The compressor 11 is, for example, a high-pressure container type variable capacity compressor that can change its operating capacity by being driven by an electric motor (not shown) whose speed is controlled by an inverter. The refrigerant discharge side of the compressor 11 is connected to the first valve port 12A of the four-way valve 12 via the discharge pipe 21. Furthermore, the refrigerant suction side of the compressor 11 is connected to the refrigerant discharge side of the receiver 15 via the suction pipe 22.

[0025] The four-way valve 12 is a valve used to switch the refrigerant flow direction in the refrigerant circuit 6, and it has a first valve port 12A to a fourth valve port 12D. The first valve port 12A is connected to the refrigerant discharge side of the compressor 11 via the discharge pipe 21. The second valve port 12B is connected to one side of the refrigerant inlet / outlet of the outdoor heat exchanger 13 (corresponding to the first outdoor heat exchange port 13A described later) via the outdoor refrigerant pipe 23. The third valve port 12C is connected to the refrigerant inlet side of the receiver 15 via the outdoor refrigerant pipe 26. Furthermore, the fourth valve port 12D is connected to the indoor heat exchanger 51 via the outdoor gas pipe 24.

[0026] The outdoor heat exchanger 13 facilitates heat exchange between the refrigerant and the outside air drawn into the outdoor unit 2 by the rotation of the outdoor unit fan 16. The outdoor heat exchanger 13 includes: a first outdoor heat exchange port 13A serving as a refrigerant inlet / outlet on one side; a second outdoor heat exchange port 13B serving as a refrigerant inlet / outlet on the other side; and an outdoor heat exchange intermediate section 13C connecting the first outdoor heat exchange port 13A and the second outdoor heat exchange port 13B. The first outdoor heat exchange port 13A is connected to the second valve port 12B of the four-way valve 12 via an outdoor refrigerant pipe 23. The second outdoor heat exchange port 13B is connected to the expansion valve 14 via an outdoor liquid pipe 25. The outdoor heat exchange intermediate section 13C is connected to both the first outdoor heat exchange port 13A and the second outdoor heat exchange port 13B. The outdoor heat exchanger 13 functions as a condenser during cooling operation of the air conditioner 1 and as an evaporator during heating operation of the air conditioner 1.

[0027] Expansion valve 14 is located on outdoor liquid line 25 and is an electronic expansion valve driven by a pulse motor (not shown). Expansion valve 14 adjusts its opening degree according to the number of pulses supplied by the pulse motor, thereby adjusting the amount of refrigerant flowing from expansion valve 14 into refrigerant circuit 6 (the amount of refrigerant flowing from outdoor heat exchanger 13 into indoor heat exchanger 51, or the amount of refrigerant flowing from indoor heat exchanger 51 into outdoor heat exchanger 13). When the air conditioner 1 is in heating operation, the opening degree of expansion valve 14 is adjusted so that the refrigerant discharge temperature of compressor 11 reaches the preset temperature, i.e., the target temperature.

[0028] The refrigerant inflow side of the receiver 15 is connected to the third port 12C of the four-way valve 12 via the outdoor refrigerant pipe 26. Furthermore, the refrigerant outflow side of the receiver 15 is connected to the refrigerant inflow side of the compressor 11 via the suction pipe 22. The receiver 15 separates the refrigerant flowing into it from the outdoor refrigerant pipe 26 into gaseous and liquid refrigerant, thus allowing only gaseous refrigerant to be drawn into the compressor 11.

[0029] The outdoor unit fan 16 is made of resin material and is located near the outdoor heat exchanger 13. Based on the rotation of a fan motor (not shown), the outdoor unit fan 16 draws outside air into the interior of the outdoor unit 2 through an air intake port (not shown) and discharges the outside air, which has exchanged heat with the refrigerant in the outdoor heat exchanger 13, to the outside of the outdoor unit 2 through an exhaust port (not shown).

[0030] In addition, the outdoor unit 2 is equipped with multiple sensors. A discharge temperature sensor 31 is installed on the discharge pipe 21 to detect the temperature of the refrigerant discharged from the compressor 11, i.e., the discharge temperature. An outdoor heat exchange outlet sensor 32 is installed on the outdoor liquid pipe 25 between the outdoor heat exchanger 13 and the expansion valve 14 to detect the temperature of the refrigerant flowing into or out of the second outdoor heat exchange outlet 13B. Furthermore, an external air temperature sensor 33 is installed near the air intake (not shown) of the outdoor unit 2 to detect the temperature of the external air flowing into the outdoor unit 2, i.e., the external air temperature.

[0031] Control circuit 17 receives instructions from control circuit 18 of indoor unit 3 (described later) to control outdoor unit 2. Control circuit 17 of outdoor unit 2 includes: a communication unit (not shown), a storage unit, and a control unit. The communication unit is a communication interface for communicating with the communication unit of indoor unit 3. The storage unit, for example, is a flash memory, used to store the control program of outdoor unit 2, operating status quantities such as detection values ​​corresponding to detection signals from various sensors, the drive status of compressor 11 and outdoor unit fan 16, and the rated capacity of outdoor unit 2 and the required capacity of each indoor unit 3.

[0032] Indoor unit structure

[0033] like Figure 2 As shown, the indoor unit 3 includes: an indoor heat exchanger 51, a gas pipe connection 52, a liquid pipe connection 53, an indoor unit fan 54, and a control circuit 18. The indoor heat exchanger 51, the gas pipe connection 52, and the liquid pipe connection 53 are connected to each other through refrigerant piping described later, thereby forming an indoor unit refrigerant circuit as part of the refrigerant circuit 6.

[0034] The indoor heat exchanger 51 facilitates heat exchange between the refrigerant and indoor air drawn into the indoor unit 3 through an air intake (not shown) by the rotation of the indoor unit fan 54. The indoor heat exchanger 51 includes a first indoor heat exchange port 51A serving as a refrigerant inlet / outlet on one side, a second indoor heat exchange port 51B serving as a refrigerant inlet / outlet on the other side, and an indoor heat exchange intermediate section 51C connecting the first and second indoor heat exchange ports 51A and 51B. The first indoor heat exchange port 51A is connected to a gas pipe connection 52 via an indoor gas pipe 56. The second indoor heat exchange port 51B is connected to a liquid pipe connection 53 via an indoor liquid pipe 57. The indoor heat exchange intermediate section 51C is connected to both the first and second indoor heat exchange ports 51A and 51B. When the air conditioner 1 is in heating operation, the indoor heat exchanger 51 functions as a condenser. Conversely, when the air conditioner 1 is in cooling operation, the indoor heat exchanger 51 functions as an evaporator.

[0035] The indoor unit fan 54 is made of resin material and is located near the indoor heat exchanger 51. The indoor unit fan 54 is driven to rotate by a fan motor (not shown), thereby drawing indoor air into the interior of the indoor unit 3 through the air intake (not shown) and discharging the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 51 out of the room through the exhaust (not shown).

[0036] Various sensors are installed in the indoor unit 3. An indoor heat exchange intermediate sensor 61 is installed in the indoor heat exchange intermediate section 51C, which is used to detect the temperature of the refrigerant flowing through the indoor heat exchange intermediate section 51C, i.e., the indoor heat exchange intermediate temperature. An suction temperature sensor 62 is installed near the suction port (not shown) of the indoor unit 3, which is used to detect the temperature of the indoor air flowing into the interior of the indoor unit 3, i.e., the suction temperature.

[0037] The control circuit 18 is used to control the entire air conditioner 1. Figure 3 This is a block diagram illustrating an example of the control circuit 18 of the indoor unit 3. The control circuit 18 includes an acquisition unit 41, a communication unit 42, a storage unit 43, and a control unit 44. The acquisition unit 41 acquires sensor values ​​from the various sensors described above. The communication unit 42 is a communication interface for communicating with the communication unit of the outdoor unit 2. The storage unit 43, for example, is a flash memory, used to store the control program of the indoor unit 3, operating status quantities such as detection values ​​corresponding to detection signals from various sensors, the drive status of the indoor unit fan 54, operating information sent from the outdoor unit 2 (e.g., including compressor 11 start / stop information, outdoor unit fan 16 drive status, etc.), and the rated capacity of the outdoor unit 2 and the required capacity of each indoor unit 3, etc.

[0038] Furthermore, the storage unit 43 stores a calculation model for estimating the amount of refrigerant remaining in the refrigerant circuit 6. In this embodiment, the amount of refrigerant remaining in the refrigerant circuit 6 is, for example, a relative refrigerant amount. Specifically, the storage unit 43 in this embodiment stores a calculation model for estimating the refrigerant shortage rate of the refrigerant circuit 6 (referring to the amount of reduction relative to a predetermined amount when the refrigerant is filled to 100%, as will be stated below). The calculation model includes a refrigeration calculation model 43A and a heating calculation model 43B.

[0039] The control unit 44 periodically acquires the detection values ​​of various sensors (e.g., once every 30 seconds). Based on this input information, the control unit 44 controls the entire air conditioner 1. Furthermore, the control unit 44 uses the aforementioned calculation models to calculate the refrigerant shortage rate.

[0040] Operation of the refrigerant circuit

[0041] Next, the flow of refrigerant in the refrigerant circuit 6 and the operation of each part of the air conditioner 1 during air conditioning operation in this embodiment will be explained.

[0042] When the air conditioner 1 is in heating mode, the four-way valve 12 switches to connect the first valve port 12A with the fourth valve port 12D, and the second valve port 12B with the third valve port 12C. Figure 2 (The state is shown by the solid line in the middle). Thus, the refrigerant circuit 6 is formed as a heating cycle where the indoor heat exchanger 51 functions as a condenser and the outdoor heat exchanger 13 functions as an evaporator. Furthermore, for ease of explanation, by... Figure 2 The solid arrows shown indicate the direction of refrigerant flow during heating operation.

[0043] When the refrigerant circuit 6 is in this state, the compressor 11 is driven, and the refrigerant discharged from the compressor 11 flows through the discharge pipe 21 and into the four-way valve 12, and then flows through the outdoor gas pipe 24 and into the gas pipe 5. The refrigerant flowing in the gas pipe 5 flows into the indoor unit 3 through the gas pipe connection 52. The refrigerant flowing into the indoor unit 3 flows through the indoor gas pipe 56 and then into the indoor heat exchanger 51. The refrigerant flowing into the indoor heat exchanger 51 exchanges heat with the indoor air that is drawn into the indoor unit 3 by the rotation of the indoor unit fan 54 and is condensed. That is, the indoor heat exchanger 51 functions as a condenser, and the indoor air heated by exchanging heat with the refrigerant in the indoor heat exchanger 51 is blown into the room through the exhaust port not shown, thereby heating the room where the indoor unit 3 is installed.

[0044] Refrigerant flowing from indoor heat exchanger 51 into indoor liquid pipe 57 flows out through liquid pipe connection 53 to liquid pipe 4. Refrigerant flowing into liquid pipe 4 flows into outdoor unit 2. Refrigerant flowing into outdoor unit 2 flows through outdoor liquid pipe 25 and is depressurized when passing through expansion valve 14. The refrigerant depressurized in expansion valve 14 flows through outdoor liquid pipe 25 and then into outdoor heat exchanger 13, where it exchanges heat with outside air flowing into outdoor unit 2 through the air intake (not shown) via the rotation of outdoor unit fan 16, thereby evaporating. Refrigerant flowing from outdoor heat exchanger 13 into outdoor refrigerant pipe 26 flows sequentially into four-way valve 12, outdoor refrigerant pipe 26, liquid receiver 15 and suction pipe 22, is then drawn into compressor 11 and compressed again, and then flows out through the first valve port 12A and the fourth valve port 12D of four-way valve 12 to outdoor gas pipe 24.

[0045] Furthermore, when the air conditioner 1 is operating in cooling mode, the four-way valve 12 switches to connect the first valve port 12A with the second valve port 12B, and the third valve port 12C with the fourth valve port 12D. Thus, the refrigerant circuit 6 forms a refrigeration cycle in which the indoor heat exchanger 51 functions as an evaporator, and the outdoor heat exchanger 13 functions as a condenser. Additionally, for ease of explanation, [the following is used...] Figure 2 The dashed arrows shown represent the flow of refrigerant during refrigeration operation.

[0046] When the refrigerant circuit 6 is in this state, the compressor 11 is driven. The refrigerant discharged from the compressor 11 flows through the discharge pipe 21 and into the four-way valve 12, and then flows through the outdoor refrigerant pipe 23 and into the outdoor heat exchanger 13. The refrigerant flowing into the outdoor heat exchanger 13 exchanges heat with the outdoor air drawn into the outdoor unit 2 by the rotation of the outdoor unit fan 16 and is condensed. 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 to the outside through the exhaust port not shown.

[0047] Refrigerant flowing from outdoor heat exchanger 13 into outdoor liquid line 25 is depressurized by passing through expansion valve 14. The depressurized refrigerant then flows through liquid line 4 into indoor unit 3. The refrigerant flowing into indoor unit 3 flows through indoor liquid line 57 and into indoor heat exchanger 51, where it exchanges heat with indoor air flowing into indoor unit 3 through an unshown suction port (not shown) via the rotation of indoor unit fan 54, thus evaporating. In other words, indoor heat exchanger 51 functions as an evaporator, and the cooled indoor air, after heat exchange with the refrigerant in indoor heat exchanger 51, is blown into the room through an unshown exhaust port, thereby cooling the room where indoor unit 3 is located.

[0048] The refrigerant flowing from the indoor heat exchanger 51 into the gas pipe 5 via the gas pipe connection 52 flows through the outdoor gas pipe 24 of the outdoor unit 2 and then into the fourth valve port 12D of the four-way valve 12. The refrigerant flowing into the fourth valve port 12D of the four-way valve 12 flows into the refrigerant inflow side of the receiver 15 from the third valve port 12C. The refrigerant flowing into the receiver 15 from the refrigerant inflow side is drawn into the compressor 11 via the suction pipe 22 and compressed again.

[0049] The acquisition unit 41 within the control circuit 18 acquires sensor values ​​from the discharge temperature sensor 31, the outdoor heat exchange outlet sensor 32, and the external air temperature sensor 33 via the control circuit 17 of the outdoor unit 2. Furthermore, the acquisition unit 41 acquires sensor values ​​from the indoor heat exchange intermediate sensor 61 and the intake temperature sensor 62 of the indoor unit 3.

[0050] Figure 4 This is a Morrill diagram representing the refrigeration cycle of air conditioner 1. During cooling operation, the outdoor heat exchanger 13 functions as a condenser, and the indoor heat exchanger 51 functions as an evaporator. Furthermore, during heating operation, the outdoor heat exchanger 13 functions as an evaporator, and the indoor heat exchanger 51 functions as a condenser.

[0051] Compressor 11 draws low-temperature, low-pressure gaseous refrigerant from the evaporator. Figure 4 The refrigerant in state A at point A is compressed into a high-temperature, high-pressure gaseous refrigerant (becoming...). Figure 4 The refrigerant (in state B) is discharged after being discharged. Furthermore, the temperature of the gaseous refrigerant discharged by compressor 11 is the discharge temperature, which is detected by discharge temperature sensor 31.

[0052] The condenser condenses the high-temperature, high-pressure gaseous refrigerant from compressor 11 after heat exchange with air. At this point, in the condenser, the gaseous refrigerant has completely transformed into liquid refrigerant through latent heat change, and the temperature of the liquid refrigerant decreases through sensible heat change, becoming a subcooled state. Figure 4 (The state of point C). Furthermore, the temperature at which the gaseous refrigerant changes into liquid refrigerant through latent heat change is the condensation temperature, and the temperature of the refrigerant in its subcooled state at the condenser outlet is the heat exchange outlet temperature. The heat exchange outlet temperature is detected by the outdoor heat exchange outlet sensor 32 during cooling operation. Furthermore, the refrigerant flow direction during heating operation is opposite to that during cooling operation, and the outdoor heat exchanger 13 functions as an evaporator. During heating operation, the outdoor heat exchange outlet sensor 32 is used to detect the temperature of the outdoor heat exchanger 13 to detect icing or control defrosting operation.

[0053] Expansion valve 14 reduces the pressure of the low-temperature, high-pressure refrigerant flowing from the condenser. The refrigerant reduced by expansion valve 14 becomes a two-phase refrigerant consisting of a gas and a liquid mixture. Figure 4 (The state of the refrigerant at point D).

[0054] The evaporator allows the incoming gas-liquid two-phase refrigerant to exchange heat with the air, causing it to evaporate. At this point, the gas-liquid two-phase refrigerant in the evaporator has completely transformed into a gaseous refrigerant through latent heat change, and then the temperature of the gaseous refrigerant rises through sensible heat change, reaching a superheated state. Figure 4 The refrigerant (at point A) is then drawn into compressor 11. Furthermore, the temperature at which the liquid refrigerant changes to gaseous refrigerant through latent heat change is the evaporation temperature. The evaporation temperature is the indoor heat exchange intermediate temperature detected by indoor heat exchange intermediate sensor 61 during cooling operation. Additionally, the temperature of the refrigerant drawn into compressor 11 after the evaporator has been superheated is the suction temperature. Furthermore, the refrigerant flow direction during heating operation is opposite to that during cooling operation, and indoor heat exchanger 51 functions as a condenser. During heating operation, the detection result of indoor heat exchange intermediate sensor 61 is used to calculate the target discharge temperature.

[0055] Structure of the inference model

[0056] The extrapolation model is generated using any one of multiple operating state variables (features) through a regression analysis method, namely, multiple regression analysis. Multiple regression analysis involves selecting the regression equation from the following: test results obtained using an actual air conditioner (hereinafter referred to as the physical unit) (the results of testing how the operating state variables would become when the refrigerant charge remaining in the refrigerant circuit changes due to the use of the physical unit) and multiple simulation results (the results of numerical calculations to reproduce the refrigerant circuit and calculate how the operating state variables would become relative to the remaining refrigerant charge). The equation with the smallest P-value (a pre-defined weighting parameter representing the influence of the operating state variable on the accuracy of the generated extrapolation model) and the largest possible correction value R² (representing the accuracy of the generated extrapolation model) between 0.9 and 1.0 is then used to generate the extrapolation model. Among them, the P-value and the correction value R2 are values ​​related to the accuracy of the inference model when generating the inference model through multiple regression analysis. The smaller the P-value, or the closer the correction value R2 is to 1.0, the higher the accuracy of the generated inference model.

[0057] The calculation model is a residual refrigerant dosage calculation model used to calculate the residual refrigerant dosage remaining in the refrigerant circuit 6. For example, the residual refrigerant dosage calculation model includes a refrigeration calculation model 43A and a heating calculation model 43B. In this embodiment, as described below, these calculation models are generated using test results from a physical machine and are pre-stored in the control circuit 18 of the air conditioner 1.

[0058] The refrigeration calculation model 43A is the first regression equation capable of calculating the refrigerant shortage rate during refrigeration operation with high accuracy.

[0059] First regression equation = (α1 × compressor speed) + (α2 × expansion valve opening) + (α3 × compressor discharge temperature) + (α4 × heat exchange outlet temperature) + (α5 × outside air temperature) + α6……(1)

[0060] The coefficients α1 to α6 are determined when generating the calculation model. The control unit 44 calculates the refrigerant shortage rate of the current refrigerant circuit 6 by substituting the current compressor 11 speed, expansion valve 14 opening, compressor 11 discharge temperature, outdoor heat exchange outlet temperature, and outside air temperature acquired by the acquisition unit 41 into the first regression equation. Furthermore, the reason for substituting the compressor 11 speed, expansion valve opening, compressor 11 discharge temperature, outdoor heat exchange outlet temperature, and outside air temperature is to use the features used when generating the refrigeration calculation model 43A. The compressor 11 speed is detected, for example, by a speed sensor (not shown) of the compressor 11. The expansion valve opening is adjusted, for example, by inputting a pulse signal from the control unit 44 to the stepper motor (not shown) of the expansion valve. The compressor 11 discharge temperature is detected by a discharge temperature sensor 31. Among the heat exchanger temperatures, the heat exchange outlet temperature is detected by an outdoor heat exchange outlet sensor 32. The outside air temperature is detected by an outside air temperature sensor 33.

[0061] The heating calculation model 43B is a second regression equation that can calculate the refrigerant shortage rate during heating operation with high accuracy.

[0062] The second regression equation = (α11 × compressor speed) + (α12 × expansion valve opening) + (α13 × compressor discharge temperature) + (α14 × indoor heat exchange intermediate temperature) + α15……(2)

[0063] The coefficients α11 to α15 are determined when generating the calculation model. The control unit 44 calculates the refrigerant shortage rate of the current refrigerant circuit 6 by substituting the current compressor 11 speed, expansion valve 14 opening, compressor 11 discharge temperature, and indoor heat exchange intermediate temperature acquired by the acquisition unit 41 into the second regression equation. Furthermore, the reason for substituting the compressor 11 speed, expansion valve 14 opening, compressor 11 discharge temperature, and indoor heat exchange intermediate temperature is to use the features used when generating the heating calculation model 43B. The compressor 11 speed is detected by a speed sensor (not shown) of the compressor 11. The expansion valve opening is adjusted, for example, by inputting a pulse signal from the control unit 44 to the stepper motor (not shown) of the expansion valve. The compressor 11 discharge temperature is detected by the discharge temperature sensor 31. Among the heat exchanger temperatures, the indoor heat exchange intermediate temperature is detected by the indoor heat exchange intermediate sensor 61.

[0064] As described above, the first regression equation is used to calculate the refrigerant shortage rate during cooling operation. Conversely, the second regression equation is used to calculate the refrigerant shortage rate during heating operation.

[0065] The process of calculation and processing

[0066] Figure 5 This is a flowchart illustrating an example of the processing operations of the control circuit 18 involved in the calculation process. Furthermore, in this embodiment, the control circuit 18 holds a pre-generated calculation model 43A for cooling and a calculation model 43B for heating. Figure 5 In the process, the control unit 44 within the control circuit 18 collects operating status quantities as operating data through the acquisition unit 41 (step S11). The control unit 44 performs data filtering processing, that is, extracts arbitrary operating status quantities from the collected operating data (step S12). In addition, the control unit 44 performs data cleaning processing to remove outliers or irregularities (step S13). The control unit 44 uses each regression equation to calculate the current refrigerant shortage rate of the refrigerant circuit 6 (step S14), and then the process ends. Figure 5 The processing actions shown.

[0067] Data filtering is based on preset filtering conditions, extracting only the necessary operating state variables for calculating the refrigerant shortage rate from multiple operating state variables, rather than using all of them. By substituting the operating state variables that have undergone data cleaning (removing outliers) into the regression equations of the generated estimation model, the refrigerant shortage rate can be estimated more accurately.

[0068] The preset filtering conditions include a first filtering condition, a second filtering condition, and a third filtering condition. The first filtering condition, for example, is a filtering condition for data extracted from all operating modes of air conditioner 1. The second filtering condition is a filtering condition for data extracted during cooling operation. The third filtering condition is a filtering condition for data extracted during heating operation.

[0069] The first filtering condition includes, for example, the compressor 11's drive state, operating mode identification, exclusion of special operations, exclusion of missing values ​​from the acquired values, and selection of values ​​with smaller changes for operating state quantities that have a significant impact on the generation of various regression equations. The compressor 11's drive state is a condition that needs to be judged because unless the compressor operates stably, allowing refrigerant to circulate in the refrigerant circuit 6, the refrigerant shortage rate cannot be calculated. This is a filtering condition used to remove operating state quantities detected during the transition period, such as when the compressor 11 starts up, and to extract only operating state quantities after, for example, the discharge temperature has reached a preset temperature, i.e., the target temperature. For example, as a filtering condition, operating state quantities where the absolute value of the difference between the discharge temperature and the target temperature is greater than a preset value are removed, and operating state quantities where the absolute value of the difference between the discharge temperature and the target temperature is less than a preset value are extracted. The preset value is, for example, the absolute value of the difference between the target discharge temperature and the detected discharge temperature is less than 2°C.

[0070] Operating mode identification is a filter condition used to extract only the operating status quantities acquired during cooling and heating operations. Therefore, operating status quantities acquired during dehumidification or air supply operations are removed. Special operation exclusion is a filter condition used to remove operating status quantities acquired during special operations, such as refrigerant oil recovery operation or defrosting operation, where the state of refrigerant circuit 6 differs significantly from that during cooling or heating operations. Exclusion of missing values ​​(values ​​that could not be obtained) refers to a filter condition that removes operating status quantities containing missing values, as using these values ​​to generate regression equations might decrease accuracy if missing values ​​exist in the operating status quantities used to determine refrigerant deficiency rate.

[0071] Selecting values ​​with smaller changes for the operating state variables substituted into each regression equation, and using the filtering condition of extracting only the operating state variables when the operating state of air conditioner 1 is in a stable state, is a necessary condition to improve the calculation accuracy based on each regression equation.

[0072] Secondary filtration conditions include, for example, the exclusion of heat exchange outlet temperature and abnormal discharge temperature.

[0073] The exclusion of heat exchange outlet temperature is a filtering condition that takes into account that the heat exchange outlet temperature detected by the outdoor heat exchange outlet sensor 32 will not be lower than the outdoor temperature detected by the outdoor temperature sensor 33 during cooling operation, since the outdoor temperature sensor 33 and the outdoor temperature sensor 32 are located close to each other. It is a filtering condition used to remove heat exchange outlet temperatures that are lower than the outdoor temperature.

[0074] The abnormal discharge temperature is a filter condition used to remove the discharge temperature detected when the intake refrigerant is reduced. This reduced intake refrigerant state is a state in which the amount of refrigerant drawn into the compressor 11 is reduced due to a smaller cooling load.

[0075] The third filtering condition is, for example, an abnormal discharge temperature. If the discharge temperature becomes high due to a large heating load during heating operation, and discharge temperature protection control is executed, the discharge temperature is reduced, for example, by reducing the speed of compressor 11, thus removing the filtering condition of the detected discharge temperature.

[0076] Data cleaning is a process used to remove operational state variables that pose a risk of erroneous estimations, rather than using all acquired operational state variables to estimate refrigerant shortage rates. Specifically, this includes smoothing the acquired operational state variables to suppress noise and limiting the amount of data. Smoothing the data to suppress noise involves calculating the average value of the interval, deriving a moving average of, for example, the suction temperature in each model, thereby suppressing noise. Limiting the amount of data means, for example, removing data with a small number of entries due to its lower reliability. For instance, if filtering a day's input data leaves more than X data points, these are used to estimate the refrigerant shortage rate; if fewer than X data points remain, all data from that day are not used. In other words, by substituting operational state variables with outliers removed into the regression equations of the estimation model during data cleaning, the refrigerant shortage rate can be estimated more accurately.

[0077] Control circuit 18 calculates the refrigerant shortage rate of refrigerant circuit 6 by substituting the current operating status quantity (sensor value) after data filtering and cleaning into the regression equations or refrigerant shortage rate calculation formulas of the calculation model. Control unit 44 within control circuit 18 determines whether the system is currently in refrigeration operation. If it is currently in refrigeration operation, control unit 44 substitutes the current operating status quantity into the refrigeration calculation model 43A to calculate the current refrigerant shortage rate.

[0078] When the system is not currently in cooling operation, but in heating operation, the control unit 44 substitutes the current operating status quantity into the heating calculation model 43B to calculate the current refrigerant shortage rate.

[0079] Methods for generating regression equations

[0080] The features used to generate the first and second regression equations will be explained below. During cooling operation using the first regression equation, the features used to generate the first regression equation through multiple regression analysis include, for example, the operating state quantities of compressor 11 speed, expansion valve 14 opening degree, compressor 11 discharge temperature, outdoor heat exchange outlet temperature, and outdoor air temperature. Furthermore, the operating state quantities used are experimental results from a physical machine. Similarly, during heating operation using the second regression equation, the features used in the multiple regression analysis include, for example, compressor 11 speed, expansion valve 14 opening degree, compressor 11 discharge temperature, and indoor heat exchange intermediate temperature. Furthermore, the operating state quantities used are experimental results from a physical machine.

[0081] Specifically, as an example, during the design phase of air conditioner 1, tests are conducted on the actual unit while indoor unit 3 is operating, by changing the outside temperature, indoor temperature, and refrigerant charge, to obtain the relationship between characteristics and refrigerant insufficiency rate. For example, the outside temperature can be varied to 20°C, 25°C, 30°C, 35°C, and 40°C during the tests. Furthermore, other parameters related to the outside temperature can also be incorporated into the tests.

[0082] Any operating state quantity (feature) used in the extrapolation model among multiple operating state quantities is derived from experimental results (hereinafter referred to as training data) representing the relationship between multiple operating state quantities and refrigerant charge. Furthermore, as training data, there exists training data that correlates the remaining refrigerant charge with each operating state quantity (training data used to generate the extrapolation model using multiple regression analysis), and training data that correlates whether the remaining refrigerant charge is in a state without excessive deficiency (e.g., the remaining refrigerant charge is reduced compared to the initial refrigerant charge but still sufficient to maintain the user's required cooling or heating capacity (normal state)) or in a state of insufficient remaining refrigerant charge (unable to maintain the user's required cooling or heating capacity (abnormal state)) with each operating state quantity (training data used to generate the extrapolation model that classifies normal and abnormal states).

[0083] In multiple regression analysis, for example, by changing the refrigerant charge to conduct tests on the actual machine, we can obtain various operating state quantities that differ according to the external temperature and classify them into data under each refrigerant charge. Figure 6This is an explanatory diagram showing an example of training data used for multiple regression analysis. The operating state variables used for the training data include, for example, the operating state variables of compressor 11, indoor unit 3, and outdoor unit 2. Operating state variables of compressor 11 include, for example, speed, target speed, operating time, discharge temperature, target discharge temperature, and output voltage. Furthermore, operating state variables of indoor unit 3 include, for example, fan speed, target fan speed, and intermediate sensor temperature of the heat exchanger. Furthermore, operating state variables of outdoor unit 2 include, for example, fan speed, target fan speed, expansion valve opening, target expansion valve opening, and outlet sensor temperature of the heat exchanger. And, as... Figure 6 As shown, the data for each refrigerant charge is used as training data for machine learning, thereby extracting arbitrary operating state quantities (features) for estimating the remaining refrigerant charge and deriving coefficients to generate an estimation model.

[0084] Figure 7 This is an illustrative diagram representing an example of training data used to generate a predictive model that classifies residual cooling dose as normal or abnormal. For example... Figure 7 As shown, machine learning is performed using training data to extract arbitrary operating state quantities (features) for estimating whether the residual cooling dose is normal and derive coefficients to generate an estimation model.

[0085] Effects of Example 1

[0086] In the air conditioner 1 of Example 1, a calculation model is used, along with current operating state quantities (compressor speed, compressor refrigerant discharge temperature, heat exchanger temperature (intermediate indoor heat exchange temperature, outdoor heat exchange outlet temperature), expansion valve opening, and outside air temperature) obtained from a limited set of sensors, to calculate the refrigerant shortage rate. The calculation model is generated using multiple regression analysis, employing operating state quantities related to the calculation of the refrigerant shortage rate of the refrigerant filling the refrigerant circuit 6. As mentioned earlier, the operating state quantities used to generate the calculation model are data obtained by experimentally running the air conditioner 1 under various environments. Therefore, in calculating the refrigerant shortage rate using this calculation model, operating state quantities obtained when the user operates the air conditioner 1 under normal conditions (cooling or heating, etc.) can be used. As a result, even for a household air conditioner 1, the current refrigerant shortage rate can be calculated without adjusting the refrigerant circuit 6 to its default state.

[0087] The calculation model installed in the air conditioner 1 is pre-generated using regression analysis by using the operating state variables that have a significant impact on the calculated refrigerant shortage rate of the refrigerant filled in the refrigerant circuit 6 from among multiple operating state variables. For this calculation model, not all operating state variables are used, but the operating state variables that have a significant impact on the calculation model are selected to generate the calculation model, thus enabling the generation of a highly accurate calculation model.

[0088] The refrigeration calculation model for air conditioner 1 is generated using the compressor speed 11, expansion valve opening, compressor discharge temperature 11, heat exchange outlet temperature, and outside air temperature as the operating state variables that have a significant impact on refrigeration operation, through regression analysis. The result is a high-precision refrigeration calculation model for refrigeration operation.

[0089] The heating calculation model for air conditioner 1 is generated using regression analysis, taking the compressor speed 11, the opening degree of expansion valve 14, the discharge temperature of compressor 11, and the indoor heat exchange intermediate temperature as the major operating parameters affecting heating operation. The result is a high-precision heating calculation model for heating operation.

[0090] In air conditioner 1, a refrigerant shortage rate during cooling operation is calculated using a calculation model for cooling and the current operating status parameters during cooling operation. Similarly, a refrigerant shortage rate during heating operation is calculated using a calculation model for heating and the current operating status parameters during heating operation. As a result, even a household air conditioner 1 can calculate the refrigerant shortage rate with high accuracy by using different calculation models for each operating state.

[0091] In the multiple regression analysis, the current operating status variables (sensor values) after data filtering and cleaning are substituted into the regression equations of the estimation model. In this embodiment, the regression equations of the estimation model are generated using features obtained through simulation, which do not contain outlier values ​​or values ​​that are significantly larger or smaller than other values. By substituting the operating status variables, which have been filtered and cleaned to remove outliers, into the regression equations of this estimation model generated using features that do not contain outliers, the refrigerant shortage rate can be estimated more accurately.

[0092] Furthermore, the embodiments described above illustrate a situation where, during the design phase of the air conditioner 1, various operating state quantities are obtained through experiments on a physical machine, and a calculation model is obtained by having a terminal such as a server with learning capabilities learn from the experimental results, with the control circuit 18 pre-stored in this calculation model. However, a calculation model obtained by learning simulation results can also be pre-stored instead of the above situation. Further, a server 120 connected to the air conditioner 1 via a communication network 110 can also exist, which generates a first regression equation and a second regression equation and sends them to the air conditioner 1. This embodiment will be described below.

[0093] Example 2

[0094] Structure of air conditioning system

[0095] Figure 8 This is an explanatory diagram illustrating an example of the air conditioning system 100 of Embodiment 2. Furthermore, the same symbols are used to denote structures identical to those in the air conditioner 1 of Embodiment 1, thus omitting descriptions of repetitive structures and operations. Figure 8 The air conditioning system 100 shown includes: an air conditioner 1, a communication network 110, and a server 120. The air conditioner 1 has an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 has a compressor 11, an outdoor heat exchanger 13, and an expansion valve 14. The indoor unit 3 has an indoor heat exchanger 51. The air conditioner 1 has a refrigerant circuit 6 that connects the outdoor unit 2 and the indoor unit 3 through refrigerant piping such as liquid pipes 4 and gas pipes 5. The refrigerant circuit 6 is filled with a preset amount of refrigerant.

[0096] Server 120 includes a generation unit 121 and a transmission unit 122. The generation unit 121 generates a calculation model using multiple regression analysis, based on operating state quantities related to the calculation of the refrigerant shortage rate of the refrigerant filled in the refrigerant circuit 6. Furthermore, the calculation model includes, for example, the refrigeration calculation model 43A and the heating calculation model 43B described in the first embodiment. The transmission unit 122 transmits each calculation model generated by the generation unit 121 to the air conditioner 1 via the communication network 110. The control circuit 18 within the air conditioner 1 uses the received calculation models to calculate the refrigerant shortage rate in the refrigerant circuit 6 of the air conditioner 1.

[0097] The generation unit 121 within the server 120 periodically collects operating status quantities during refrigeration operation from a standard unit of the air conditioner 1 (located in the manufacturer's laboratory, etc.) capable of actually measuring the refrigerant deficiency rate in the refrigerant circuit 6. Using the comparison results between the refrigerant deficiency rate calculated by each calculation model and the actually measured refrigerant deficiency rate, along with the collected operating status quantities, it generates or updates the refrigeration calculation model 43A. Furthermore, the transmission unit 122 within the server 120 periodically sends the generated or updated refrigeration calculation model 43A to the air conditioner 1. Alternatively, as in Embodiment 1, the operating status quantities used to generate each calculation model can be obtained through simulation, and the generation unit 121 uses the operating status quantities obtained through simulation to generate each calculation model.

[0098] The generation unit 121 within the server 120 periodically collects operating status data during heating operation from the standard unit of the air conditioner 1 described above. Using a comparison between the refrigerant shortage rate calculated by the calculation model and the actual measured refrigerant shortage rate, along with the collected operating status data, it generates a heating calculation model 43B. Furthermore, the transmission unit 122 within the server 120 periodically sends the generated heating calculation model 43B to the air conditioner 1. Alternatively, as in Embodiment 1, the operating status data used to generate each calculation model can be obtained through simulation, and the generation unit 121 uses the simulated operating status data to generate each calculation model.

[0099] Effects of Example 2

[0100] In Example 2, server 120 uses operating status variables related to the calculation of refrigerant shortage rate in the refrigerant circuit 6, employs multiple regression analysis to generate a calculation model for calculating the refrigerant shortage rate, and sends the generated calculation model to air conditioner 1. Air conditioner 1 uses the calculation model received from server 120 and the current operating status variables to calculate the refrigerant shortage rate. As a result, even a household air conditioner 1 can use a highly accurate calculation model to calculate the current refrigerant shortage rate.

[0101] Furthermore, this embodiment describes the case where the relative refrigerant charge is calculated to represent the refrigerant charge remaining in the refrigerant circuit 6. Specifically, it describes the case where a refrigerant shortage rate is calculated and provided, which is the ratio of the refrigerant charge leaking from the refrigerant circuit 6 to the amount of refrigerant added when filling the refrigerant circuit 6 (initial value). However, the present invention is not limited to this; the calculated refrigerant shortage rate can also be multiplied by the initial value to provide the refrigerant charge leaking from the refrigerant circuit 6 to the outside. In addition, a calculation model for calculating the absolute refrigerant charge leaking from the refrigerant circuit 6 to the outside or the absolute refrigerant charge remaining in the refrigerant circuit 6 can be generated, and the calculation result based on the calculation model can be provided. When generating a calculation model for calculating the absolute refrigerant charge leaking from the refrigerant circuit 6 to the outside or the absolute refrigerant charge remaining in the refrigerant circuit 6, in addition to the various operating state quantities described so far, it is sufficient to consider the volumes of the outdoor heat exchanger 13 and the indoor heat exchanger 51, as well as the volume of the liquid pipe 4.

[0102] Variations

[0103] This embodiment illustrates the case where the control circuit 18 of the indoor unit 3 controls the entire air conditioner 1, but the control circuit 18 can also be located on the outdoor unit 2 or the cloud side. This embodiment illustrates the case where the calculation model is generated by the server 120, but it is also possible to calculate the calculation model manually based on simulation results without using the server 120. Furthermore, this embodiment illustrates the case where the control circuit 18 of the indoor unit 3 uses the calculation model to calculate the refrigerant dosage, but the refrigerant dosage can also be calculated by the server 120 that generates the calculation model. Additionally, this embodiment illustrates the case where various calculation models are generated using multiple regression analysis, but machine learning algorithms capable of performing ordinary regression analysis, such as SVR (Support Vector Regression) or NN (Neural Network), can also be used to generate the calculation model. In this case, for feature selection, instead of the P-value and correction value R used in multiple regression analysis, ordinary methods for selecting features in a way that improves the accuracy of the calculation model (such as forward feature selection or backward feature elimination) can be used.

[0104] Furthermore, the structural elements of each part shown in the diagram do not necessarily have to be physically arranged as illustrated. That is, the specific form of the distribution / combination of the parts is not limited to the form shown in the diagram, and all or part of them can be distributed / combined in any unit, functionally or physically, according to various loads or usage conditions.

[0105] Furthermore, the various processing functions performed by each device can be executed, in whole or in part, on a CPU (Central Processing Unit) (or MPU (Micro Processing Unit), MCU (Micro Controller Unit), or other microcomputers). It goes without saying that these processing functions can also be executed, in whole or in part, on programs parsed and executed by the CPU (or MPU, MCU, etc.), or on hardware via wired logic.

[0106] Furthermore, in the embodiments described above, the refrigerant shortage rate is defined as the amount of refrigerant reduction calculated from the specified amount when the specified amount of refrigerant is filled to 100%. Alternatively, the refrigerant shortage rate can be calculated using the method described in this embodiment after the specified amount of refrigerant has just been filled into the refrigerant circuit 6, and the calculated result can be taken as 100%. For example, if the calculated refrigerant shortage rate is 90% after the specified amount of refrigerant has just been filled into the refrigerant circuit 6, that is, if the amount of refrigerant filled into the refrigerant circuit 6 is calculated to be 10% less than the specified amount, the amount of refrigerant that is 10% less than the specified amount can also be defined as 100%. By combining the refrigerant amount defined as 100% with the calculated result, the subsequent refrigerant shortage rate can be calculated more accurately.

[0107] Symbol Explanation

[0108] 1. Air conditioner

[0109] 2 Outdoor unit

[0110] 3 Indoor unit

[0111] 4 liquid tubes

[0112] 5. Trachea

[0113] 11 Compressor

[0114] 12 Four-way valve

[0115] 13 Outdoor heat exchanger

[0116] 13A First Outdoor Heat Exchanger Port

[0117] 13B Second Outdoor Heat Exchanger Port

[0118] 13C Outdoor Heat Exchange Intermediate Section

[0119] 14 Expansion valve

[0120] 18 Control Circuit

[0121] 31 Discharge temperature sensor

[0122] 32 Outdoor heat exchange outlet sensor

[0123] 33 External temperature sensor

[0124] 41 Acquisition Department

[0125] 43A Refrigeration Calculation Model

[0126] 43B Heating Calculation Model

[0127] 44 Control Department

[0128] 51 Indoor heat exchanger

[0129] 51A First Indoor Heat Exchanger Port

[0130] 51B Second Indoor Heat Exchanger Port

[0131] 51C Indoor Heat Exchange Intermediate Section

[0132] 61 Indoor heat exchange intermediate sensor

[0133] 62 Inhalation Temperature Sensor

Claims

1. An air conditioner comprising a refrigerant circuit connecting an indoor unit to an outdoor unit via refrigerant piping, wherein the outdoor unit includes a compressor, an outdoor heat exchanger, and an expansion valve, the indoor unit includes an indoor heat exchanger, and the refrigerant circuit is filled with a preset amount of refrigerant; the air conditioner is characterized in that... It has a residual cooling dose estimation model. The residual refrigerant charge estimation model uses at least the operating state variables representing the operating state of the air conditioner, including the compressor speed, the compressor refrigerant discharge temperature, the heat exchanger temperature, the expansion valve opening, and the outside air temperature, to estimate the residual refrigerant charge remaining in the refrigerant circuit. This estimation of the residual refrigerant charge is performed during both heating and cooling operations of the air conditioner. The indoor heat exchanger has: A first indoor heat exchange port for the refrigerant to flow through; a second indoor heat exchange port for the refrigerant to flow through; an intermediate indoor heat exchange section connecting the first and second indoor heat exchange ports; and an intermediate indoor heat exchange sensor located in the intermediate indoor heat exchange section for detecting the temperature of the refrigerant flowing through the intermediate indoor heat exchange section as part of the heat exchanger's temperature range. The outdoor heat exchanger has the following features: A first outdoor heat exchange port for the refrigerant to flow through; a second outdoor heat exchange port for the refrigerant to flow through; an outdoor heat exchange intermediate section connecting the first outdoor heat exchange port and the second outdoor heat exchange port; and an outdoor heat exchange outlet sensor located at the second outdoor heat exchange port for detecting the temperature of the refrigerant flowing through the outdoor heat exchange outlet of the second outdoor heat exchange port during refrigeration operation.

2. The air conditioner according to claim 1, characterized in that, There is only one outdoor unit, one indoor unit, and one expansion valve.

3. The air conditioner according to claim 1, characterized in that, The residual refrigerant dosage estimation model uses the operating state quantity when the absolute value of the difference between the refrigerant discharge temperature and the target temperature of the compressor is below a preset value to estimate the residual refrigerant dosage.

4. The air conditioner according to claim 1, characterized in that, The residual refrigerant dosage estimation model uses the compressor speed, the compressor refrigerant discharge temperature, the heat exchanger temperature, the expansion valve opening, the external air temperature, and the residual refrigerant dosage remaining in the refrigerant circuit as training data for machine learning.

5. The air conditioner according to claim 4, characterized in that, The residual cooling dose estimation model is a linear regression equation.

6. The air conditioner according to claim 1, characterized in that, The residual refrigerant dosage estimation model uses the compressor speed, the compressor refrigerant discharge temperature, the heat exchanger temperature, the expansion valve opening, the external air temperature, and the judgment result of whether the residual refrigerant dosage in the refrigerant circuit is normal as training data for machine learning.

7. The air conditioner according to claim 1, characterized in that, The calculation of the remaining refrigerant charge is performed without refrigerant filling.

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