Information processing device and air conditioning system

Abstract

An information processing device according to one embodiment of the present invention comprises a calculating unit and a determining unit. The calculating unit calculates a first refrigerant state quantity and a second refrigerant state quantity. The first refrigerant state quantity is an estimated value of a state quantity relating to a refrigerant on a refrigerant suction side of a compressor, the estimated value being calculated on the basis of an operating state quantity relating to the drive of the compressor when a refrigerant circuit is in a space heating cycle. The second refrigerant state quantity is an estimated value of a state quantity relating to the refrigerant flowing through an outdoor expansion valve, the estimated value being calculated using a capacity coefficient of the outdoor expansion valve. The determining unit compares the second refrigerant state quantity with the first refrigerant state quantity, or compares the second refrigerant state quantity with a predetermined reference value, to determine whether or not the amount of refrigerant, which is the amount of refrigerant circulating through the refrigerant circuit, has decreased.

Description

Information processing apparatus and air conditioning system

[0001] The present invention relates to an information processing apparatus that monitors the state of a refrigerant flowing in a refrigerant circuit of an air conditioner, and an air conditioning system including the same.

[0002] In an air conditioner in which a plurality of indoor units are connected to a single outdoor unit, various techniques have been proposed for estimating the amount of refrigerant charged in a refrigerant circuit and detecting an excess or deficiency of the refrigerant. For example, Patent Document 1 discloses a method for determining the amount of refrigerant circulating in a refrigerant circuit by using the degree of supercooling of the refrigerant flowing out from an outdoor heat exchanger when a refrigerant amount determination operation mode is executed in which the evaporation pressure is kept constant while keeping the degree of superheat of the refrigerant flowing out from an indoor heat exchanger at a positive value.

[0003] In the technique described in Patent Document 1, the refrigerant amount determination operation mode is executed after setting the refrigerant circuit to a cooling cycle, and if the detected degree of supercooling is smaller than a predetermined value, it is determined that the refrigerant amount is insufficient relative to a specified value, for example, the amount of refrigerant required to exhibit the intended performance in the refrigerant circuit.

[0004] Japanese Unexamined Patent Application Publication No. 2006-23072

[0005] However, the technique described in Patent Document 1 has a problem that when the refrigerant circuit is in a heating cycle, a shortage of the refrigerant amount cannot be detected for the following reasons.

[0006] That is, in an air conditioner in which a plurality of indoor units are connected to a single outdoor unit, each indoor heat exchanger functions as a condenser during a heating cycle. Therefore, for example, it is necessary to calculate the degree of supercooling for each indoor heat exchanger, obtain an average value of these calculated values, and then determine the degree of supercooling to be used for determining whether the refrigerant amount is insufficient relative to a specified value. Since a plurality of degrees of supercooling are handled in this way to determine whether there is a shortage of refrigerant amount, when there is an indoor unit with extremely different operating conditions, the average value of the degree of supercooling used for determination is affected by the degree of supercooling of that indoor unit, making it impossible to improve determination accuracy.

[0007] In view of the above circumstances, the object of the present invention is to provide an information processing device and an air conditioning system equipped therewith that can accurately determine whether or not there is a shortage of refrigerant during heating operation, even in an air conditioning system in which multiple indoor units are connected to a single outdoor unit.

[0008] An information processing device according to one embodiment of the present invention is an information processing device for managing the state of an outdoor unit of an air conditioning system having a compressor, an outdoor heat exchanger, and an outdoor expansion valve, and comprises a calculation unit and a determination unit. The calculation unit calculates a first refrigerant state quantity and a second refrigerant state quantity. The first refrigerant state quantity is an estimated value of the state quantity related to the refrigerant on the refrigerant suction side of the compressor, calculated based on the operating state quantity related to the driving of the compressor when the refrigerant circuit is in a heating cycle. The second refrigerant state quantity is an estimated value of the state quantity related to the refrigerant flowing through the outdoor expansion valve, calculated using the capacity coefficient of the outdoor expansion valve. The determination unit determines whether or not there has been a decrease in the amount of refrigerant, which is the amount of refrigerant circulating in the refrigerant circuit, by comparing the second refrigerant state quantity with the first refrigerant state quantity, or by comparing the second refrigerant state quantity with a predetermined reference value.

[0009] According to the above-described information processing device, during heating operation, it is possible to accurately determine whether there is a decrease or shortage in the amount of refrigerant using only the information obtainable from the outdoor unit 2, without using information from the indoor units 8a to 8c.

[0010] An air conditioning system according to one embodiment of the present invention comprises an air conditioning device and an information processing device. The air conditioning device has a refrigerant circuit including an outdoor unit having a compressor, an outdoor heat exchanger and an outdoor expansion valve, an indoor unit having an indoor heat exchanger and refrigerant piping connecting the outdoor unit and the indoor unit. The information processing device manages the state of the air conditioning device. The information processing device comprises a calculation unit and a determination unit. The calculation unit calculates a first refrigerant state quantity and a second refrigerant state quantity. The first refrigerant state quantity is an estimated value of the refrigerant state quantity on the refrigerant suction side of the compressor, calculated based on the operating state quantity related to the driving of the compressor when the refrigerant circuit is in a heating cycle. The second refrigerant state quantity is an estimated value of the refrigerant state quantity flowing through the outdoor expansion valve, calculated using the capacity coefficient of the outdoor expansion valve. The determination unit determines whether or not there has been a decrease in the amount of refrigerant circulating in the refrigerant circuit by comparing the second refrigerant state quantity with the first refrigerant state quantity, or by comparing the second refrigerant state quantity with a predetermined reference value.

[0011] According to the present invention, even in an air conditioning system in which multiple indoor units are connected to a single outdoor unit, it is possible to accurately determine whether or not there is a shortage of refrigerant during heating operation.

[0012] 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 device. This is a block diagram showing the configuration of an information processing device according to one embodiment of the present invention. This is a diagram illustrating the relationship between the flow rate ratio of the first refrigerant mass flow rate and the second refrigerant mass flow rate and the threshold. This is a flowchart showing an example of the processing procedure of the above information processing device. This is a flowchart showing another example of the processing procedure of the above information processing device. This is a diagram showing an example of the relationship between the temperature and pressure of the refrigerant drawn into the compressor and the refrigerant density.

[0013] Embodiments of the present invention will be described below with reference to the drawings.

[0014] <First Embodiment> 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 an information processing device 200.

[0015] [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.

[0016] 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.

[0017] (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.

[0018] 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.

[0019] 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 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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 for detecting the pressure of the refrigerant discharged from the compressor 21 and a discharge temperature sensor 53 for detecting the temperature of the refrigerant discharged from the compressor 21. The suction pipe 42 is equipped with a low-pressure sensor 51 for detecting the pressure of the refrigerant drawn into the compressor 21 and a suction temperature sensor 54 for detecting the temperature of the refrigerant drawn into the compressor 21.

[0025] 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. An outside air temperature sensor 58 is also provided that detects the temperature of the outside air flowing into the outdoor unit 2, i.e., the outside air temperature. In addition, a refrigerant sensor 52 is provided in the outdoor unit liquid pipe 35 between the outdoor expansion valve 29 and the liquid side shut-off valve 45 that detects the temperature or pressure of the refrigerant on the inlet side of the outdoor expansion valve 29 when the refrigerant circuit 10 is in a heating cycle.

[0026] (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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] (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.

[0032] 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.

[0033] 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.

[0034] 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 information processing 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.

[0035] 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 an information processing device 200 or the internet.

[0036] 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.

[0037] 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 29, 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 and the detection results from the rotation speed detection unit 95, acquired via the sensor input unit 94, to the information processing device 200, which will be described later, via the second communication unit 96.

[0038] [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.

[0039] (Cooling Operation) When the air conditioning system 100 performs cooling operation, the four-way valve 22 of the outdoor unit 2 is switched so that port a and port b are in communication, and port c and port d are in communication (shown by dashed lines in Figure 1), thereby causing the outdoor heat exchanger 24 to function as a condenser.

[0040] 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 from the four-way valve 22 flows into the outdoor heat exchanger 24 through the refrigerant pipe 37, exchanges heat with outdoor 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 stop valve 45. The intermediate-pressure refrigerant that has flowed into the liquid pipe 31 branches and flows into each of the indoor units 8a to 8c through the liquid branch pipe 71.

[0041] The intermediate-pressure refrigerant that has flowed into each of the indoor units 8a to 8c is decompressed by the indoor expansion valve 82 to become low-pressure refrigerant, and then flows into the indoor heat exchanger 81. The low-pressure refrigerant that has flowed into the indoor heat exchanger 81 exchanges heat with indoor air and evaporates, thereby cooling the room where the indoor units 8a to 8c are installed. At this time, the refrigerant superheat degree at the outlet of the indoor heat exchanger 81, which serves as an evaporator, is obtained from the refrigerant temperatures detected by the refrigerant temperature sensors 84 and 85, and the opening degree of the indoor expansion valve 82 is adjusted accordingly.

[0042] The low-pressure refrigerant flowing out from 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 that has flowed 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.

[0043] (Heating Operation) When the air conditioner 100 performs a heating operation, the four-way valve 22 of the outdoor unit 2 is switched such that port a communicates with port d and port b communicates with port c (shown by solid lines in Fig. 1), thereby causing the outdoor heat exchanger 24 to function as an evaporator.

[0044] 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 from 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 that has flowed into the gas pipe 32 flows into the indoor units 8a to 8c through the gas branch pipe 72.

[0045] The high-pressure refrigerant that has flowed 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 depressurized. 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.

[0046] 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 stop 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 a low-pressure refrigerant. The opening degree of the outdoor expansion valve 29 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.

[0047] 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.

[0048] [Information Processing Apparatus] The information processing apparatus 200 is a management apparatus that manages the state of the outdoor unit 2, and is installed in a management room or the like that remotely manages the air conditioning apparatus 100. The information processing apparatus 200 is connected to the second communication unit 96 of the air conditioning apparatus 100 via a network such as the Internet line or a wide area communication network, for example. In the present embodiment, the information processing apparatus 200 estimates the amount of refrigerant circulating in the refrigerant circuit 10 (hereinafter also referred to as refrigerant amount) based on the detection results from various sensors of the outdoor unit 2 captured by the sensor input unit 94, the detection result from the rotation speed detection unit 95, and the like.

[0049] Figure 3 is a block diagram showing the configuration of the information processing device 200. The information processing device 200 has hardware necessary for a computer, such as a processor such as a CPU, memory such as ROM and RAM, and storage devices such as an HDD.

[0050] A database 220 is connected to the information processing device 200. The database 220 functions as a storage unit and stores various information received from the air conditioning system 100. Parameters necessary for the calculation of the refrigerant mass flow rate, which will be described later in the information processing device 200, such as the exhaust volume of the compressor 21 and the capacity coefficient of the outdoor expansion valve 29, are pre-stored in the database 220.

[0051] The information processing device 200 includes, as functional blocks of the CPU, an acquisition unit 201, an arithmetic unit 202, a determination unit 203, and a signal generation unit 204.

[0052] (Acquisition Unit) The acquisition unit 201 receives data acquired by the sensor input unit 94 and data detected by the rotation speed detection unit 95 from the air conditioner 100 at predetermined intervals (e.g., every 30 minutes) and stores them in the database 220. The predetermined interval is set to be longer than the data acquisition cycle (e.g., 1 minute) of the sensor input unit 94 and the data detection cycle (e.g., 1 minute) of the rotation speed detection unit 95. The acquisition unit 201 may receive data acquired by the sensor input unit 94 and data detected by the rotation speed detection unit 95 at the timing of the predetermined interval, or it may receive all the data acquired by the sensor input unit 94 for the predetermined interval and all the data detected by the rotation speed detection unit 95 for the predetermined interval.

[0053] (Calculation Unit) The calculation unit 202 includes a first refrigerant state quantity calculation unit 202a and a second refrigerant state quantity calculation unit 202b.

[0054] The first refrigerant state quantity calculation unit 202a calculates a first refrigerant state quantity, which is an estimated value of the state of the refrigerant on the refrigerant suction side of the compressor 21, based on the operating state quantity related to the drive of the compressor 21 when the refrigerant circuit 10 is in a heating cycle.

[0055] Operating state variables related to the drive of the compressor 21 include, for example, the rotational speed of the compressor 21 and the suction temperature or discharge temperature of the compressor 21. In this embodiment, the first refrigerant mass flow rate, which is an estimated value of the mass flow rate of the refrigerant on the refrigerant suction side of the compressor 21, is calculated as the first refrigerant state variable using the rotational speed of the compressor 21.

[0056] More specifically, the first refrigerant state quantity calculation unit 202a uses the rotational speed of the compressor 21, the first refrigerant density (which is the density of the refrigerant drawn into the compressor 21), and the exhaust volume of the compressor 21 to calculate the first refrigerant mass flow rate (unit: kg / s) using the following equation (1): First refrigerant mass flow rate = First refrigerant density × Compressor exhaust volume × Compressor rotational speed …(1)

[0057] The first refrigerant density is the refrigerant density when the dryness degree is 1, and can be determined using the detected value of the low-pressure sensor 51 or the intake temperature sensor 54 of the outdoor unit 2. Since the refrigerant drawn into the compressor 21 is always gaseous (with a dryness degree of 1) refrigerant due to intake superheat control, the first refrigerant mass flow rate is constant regardless of the amount of refrigerant. The compressor exhaust volume is stored in the database 220 as known data. The compressor rotation speed is determined by the detected value of the rotation speed detection unit 95.

[0058] The second refrigerant state quantity calculation unit 202b calculates a second refrigerant state quantity, which is an estimated value of the state quantity related to the refrigerant flowing through the outdoor expansion valve 29, using the capacity coefficient of the outdoor expansion valve 29 when the refrigerant circuit 10 is in a heating cycle.

[0059] The capacity coefficient, also known as the flow coefficient or Cv value of the expansion valve, is a unique coefficient that indicates the ease with which the refrigerant flows through the expansion valve. A larger value means less pressure loss to the refrigerant in the expansion valve and easier flow. The capacity coefficient is stored in the database 220 as known data. The capacity coefficient has different values ​​depending on the specifications and type of expansion valve, and generally serves as an indicator of the expansion valve's performance. Therefore, the second refrigerant mass flow rate can be calculated without requiring prior calibration.

[0060] Furthermore, if the capacity coefficient of the outdoor expansion valve 29 is unknown, the second refrigerant state calculation unit 202b may calculate the capacity coefficient corresponding to the opening degree of the outdoor expansion valve 29 from the opening degree of the outdoor expansion valve 29, and use the calculated capacity coefficient to calculate the second refrigerant mass flow rate. Since there is a correlation between the capacity coefficient (Cv value) and the opening degree, the capacity coefficient corresponding to the opening degree can be obtained by performing a calibration process in advance to associate the opening degree of the expansion valve with the capacity coefficient.

[0061] Here, calibration refers to determining the relationship between the opening degree of the outdoor expansion valve 29 and the capacity coefficient, and the model is carried out using the following procedure: (1) Calculation of the capacity coefficient during trial operation During trial operation after the installation of the air conditioning system 1, the compressor 21 is driven at a predetermined rotational speed to obtain the suction flow rate Q of the refrigerant drawn into the compressor 21 and the pressure difference ΔP before and after the outdoor expansion valve 29, and the capacity coefficient Cv is calculated using the following formula (A): Cv = Q / √ΔP ... (A) (2) Construction of a relationship between the opening degree of the expansion valve and the capacity coefficient The (approximate) relationship between a general capacity coefficient and the opening degree of the outdoor expansion valve 29 is as follows: Cv = a × (expansion valve opening degree) ｂ × c ... (B) In the above equation (B), each of the constants a, b, and c is a value obtained by determining the capacity coefficient by varying the rotational speed of the compressor 21 and referring to it in conjunction with the opening degree of the outdoor expansion valve 29 for each capacity coefficient. Alternatively, the above relationship can be obtained by machine learning using the opening degrees and capacity coefficients of multiple outdoor expansion valves 29 as training data.

[0062] State variables relating to the refrigerant flowing through the outdoor expansion valve 29 include, for example, the mass flow rate of the refrigerant flowing through the outdoor expansion valve 29 and the density of the refrigerant flowing through the outdoor expansion valve 29. In this embodiment, as a second refrigerant state variable, the second refrigerant mass flow rate, which is an estimated value of the mass flow rate of the refrigerant flowing through the outdoor expansion valve 29, is calculated using the capacity coefficient of the outdoor expansion valve 29.

[0063] More specifically, the second refrigerant state calculation unit 202b uses the capacity coefficient of the outdoor expansion valve 29, the second refrigerant density (which is the density of the liquid refrigerant flowing into the outdoor expansion valve 29), and the pressure difference of the refrigerant between the inlet side (intermediate pressure) and the outlet side (low pressure) of the outdoor expansion valve 29 to calculate the second refrigerant mass flow rate (unit: kg / s) using the following equation (2): Second refrigerant mass flow rate = capacity coefficient × {(intermediate pressure - low pressure) / second refrigerant density} １／２ …(2)

[0064] The intermediate pressure is determined by the detection result of the refrigerant sensor 52, which detects the temperature or pressure of the refrigerant on the inlet side of the outdoor expansion valve 29 during the heating cycle, and the low pressure is determined by the detection value of the low-pressure sensor 51. Although the refrigerant passing through the outdoor expansion valve 29 is almost always in a gas-liquid two-phase state, assuming that 100% of the refrigerant becomes liquid refrigerant at the condenser outlet when there is a specified amount of refrigerant, when calculating the second refrigerant mass flow rate using equation (2), it is assumed that the refrigerant passing through the outdoor expansion valve 29 is liquid refrigerant and the density of liquid refrigerant is used. This makes it easier to confirm the change in the second refrigerant mass flow rate because the refrigerant changes from the liquid phase to a gas-liquid two-phase state when the amount of refrigerant decreases.

[0065] (Determination Unit) The determination unit 203 determines whether or not there is a decrease in the amount of refrigerant circulating in the refrigerant circuit 10, based on the first refrigerant mass flow rate (first refrigerant state quantity) and the second refrigerant mass flow rate (second refrigerant state quantity). In this embodiment, the determination of whether or not there is a decrease in the amount of refrigerant is made by comparing the second refrigerant mass flow rate with the first refrigerant mass flow rate.

[0066] For example, if there is a shortage of refrigerant circulating in the refrigerant circuit 10 when the refrigerant circuit is in a heating cycle, the opening degree of the outdoor expansion valve 29 is adjusted to be larger than when there is no shortage of refrigerant, so the capacity coefficient (Cv value) of the outdoor expansion valve 29 becomes larger. As a result, the value of the second refrigerant mass flow rate calculated by equation (2) becomes larger than the value of the second refrigerant mass flow rate calculated when there is no shortage of refrigerant.

[0067] Therefore, in this embodiment, the second refrigerant mass flow rate is compared with the first refrigerant mass flow rate, and the presence or absence of a decrease in the amount of refrigerant in the refrigerant circuit 10 is determined based on how much larger the second refrigerant mass flow rate is compared to the first refrigerant mass flow rate.

[0068] More specifically, as shown in Figure 4, the determination unit 203 determines that the amount of refrigerant is decreasing when the flow rate ratio (F2 / F1), which is the value obtained by dividing the second refrigerant mass flow rate (F2) by the first refrigerant mass flow rate (F1), is greater than or equal to a first threshold (Th1) which is a predetermined amount greater than 1. The lower limit of the flow rate ratio (F2 / F1) is 1. The first threshold (Th1) can be set based on, for example, the amount of refrigerant reduction that allows 80-90% of the target heating capacity to be achieved, and is determined in advance by experiment.

[0069] Furthermore, the determination unit 203 determines that the amount of refrigerant is insufficient when the flow rate ratio (F2 / F1) is greater than or equal to a second threshold (Th2) which is greater than the first threshold (Th1). The second threshold (Th2) can be set based on, for example, the amount of refrigerant that has decreased to the point where it is not possible to achieve 70% or more of the target heating capacity, and is determined in advance by experimentation.

[0070] The signal generation unit 204 generates an alarm signal to be transmitted to the air conditioning system 100 according to the determination result in the determination unit 203. In this embodiment, when the flow rate ratio (F2 / F1) is greater than or equal to a first threshold (Th1) and less than a second threshold (Th2), the signal generation unit 204 generates a first alarm signal indicating that the amount of refrigerant is decreasing. On the other hand, when the flow rate ratio (F2 / F1) is greater than or equal to a second threshold (Th2), the signal generation unit 204 generates a second alarm signal indicating that the amount of refrigerant is insufficient. When the signal generation unit 204 generates either the first or second alarm signal, it notifies the operator in the control room where the information processing device 200 is installed of the content of the alarm and prompts them to perform necessary maintenance on the air conditioning system 100. When the flow rate ratio (F2 / F1) is less than the first threshold (Th1), the amount of refrigerant is determined to be appropriate.

[0071] When the CPU 91 of the air conditioning system 100 receives the first alarm signal via the second communication unit 96, it may display the content of the alarm on the outdoor unit 2 or indoor units 8a to 8c to inform the user. On the other hand, when the CPU 91 receives the second alarm signal, it may immediately stop the operation of the air conditioning system 100 and also inform the user of the content of the alarm on the outdoor unit 2 or indoor units 8a to 8c.

[0072] [Operation of the Air Conditioning System] Figure 5 is a flowchart showing an example of the processing procedure of the information processing device 200 configured as described above.

[0073] After the air conditioning system 100 starts heating operation, the following process for determining the presence or absence of refrigerant is performed after the operating time necessary for the state of the refrigerant circulating in the refrigerant circuit 10 to stabilize (for example, 15 to 30 minutes) has elapsed. After the above operating time has elapsed, it is determined whether a predetermined time, which is the data acquisition cycle from the outdoor unit 2, has elapsed (ST101). If the predetermined time has elapsed (Yes in ST101), the information processing device 200 acquires the data acquired at the sensor input unit 94 and the detection data at the rotation speed detection unit 95 from the control device 90 of the air conditioning system 100 (ST102).

[0074] The information processing device 200 uses the acquired data and the data stored in the database 220 to calculate the first refrigerant mass flow rate (F1) and the second refrigerant mass flow rate (F2) (ST103), and determines whether the flow rate ratio (F2 / F1) is equal to or greater than the first threshold (Th1) (ST104).

[0075] If the above flow rate ratio (F2 / F1) is less than the first threshold (Th1) (No in ST104), it is determined that there is no decrease in the amount of refrigerant and the process returns to ST101. On the other hand, if the above flow rate ratio (F2 / F1) is equal to or greater than the first threshold (Th1), it is determined whether or not the above flow rate ratio (F2 / F1) is equal to or greater than the second threshold (Th2) (ST105).

[0076] The information processing device 200 determines that a decrease in the amount of refrigerant has occurred when the flow rate ratio (F2 / F1) is less than the second threshold (Th2) (No in ST105), generates a first alarm signal (ST106), and returns to ST101. On the other hand, when the flow rate ratio (F2 / F1) is equal to or greater than the second threshold (Th2), it determines that a shortage of refrigerant has occurred, generates a second alarm signal (ST107), and terminates processing.

[0077] As described above, according to this embodiment, during heating operation, it is possible to accurately determine whether there is a decrease or shortage in the amount of refrigerant using only the information that can be obtained on the outdoor unit 2 side, without using information from the indoor units 8a to 8c side.

[0078] In the above embodiment, a first refrigerant mass flow rate, which remains constant regardless of the amount of refrigerant, and a second refrigerant mass flow rate, which changes according to the amount of refrigerant, are calculated, and the ratio of the two (F2 / F1) is taken to determine that the change in the second refrigerant mass flow rate is a refrigerant shortage. In this way, the second refrigerant mass flow rate (mass flow rate of refrigerant flowing through the outdoor expansion valve 29), which changes according to the amount of refrigerant, is estimated based on the first refrigerant mass flow rate (mass flow rate of refrigerant on the refrigerant suction side of the compressor 21), which remains constant regardless of the amount of refrigerant. As a result, the flow rate ratio (F2 / F1), which is the value obtained by dividing the second refrigerant mass flow rate by the first refrigerant mass flow rate, can be calculated with high accuracy, thereby increasing the reliability of the determination result regarding whether or not there is a refrigerant shortage.

[0079] Furthermore, in the above embodiment, not only is it determined whether or not there is a shortage of refrigerant, but also whether or not there is a decrease in the amount of refrigerant using a threshold (Th1), so it is possible to identify in advance which air conditioning systems tend to have a shortage of refrigerant. As a result, necessary maintenance work such as refrigerant charging can be performed on the air conditioning system before it reaches a state where the amount of refrigerant is insufficient and the air conditioning capacity required by the user cannot be achieved, thereby minimizing the situation in which the operation of the air conditioning system is stopped due to a shortage of refrigerant.

[0080] <Second Embodiment> In the first embodiment described above, the information processing device 200 calculated the first refrigerant mass flow rate (F1) as the first refrigerant state quantity and the second refrigerant mass flow rate (F2) as the second refrigerant state quantity, and a method was described in which the decrease or shortage of refrigerant amount was determined by comparing the ratio of these flow rates (F2 / F1) with predetermined thresholds (Th1, Th2). Instead, in this embodiment, the density of the refrigerant is calculated instead of the refrigerant mass flow rate as the first and second refrigerant state quantities, and a method is described in which the decrease or shortage of refrigerant amount is determined by comparing the obtained density of the refrigerant with predetermined thresholds.

[0081] Figure 6 is a flowchart showing another example of the processing procedure of the information processing device 200. Below, the information processing device 200 of this embodiment will be described, focusing on the differences from the first embodiment.

[0082] After the air conditioning system 100 starts heating operation and the above operating time has elapsed, it is determined whether a predetermined time, which is the data acquisition cycle from the outdoor unit 2, has elapsed (ST201). If the predetermined time has elapsed (Yes in ST201), the information processing device 200 acquires the data acquired at the sensor input unit 94 and the data detected at the rotation speed detection unit 95 from the control device 90 of the air conditioning system 100 (ST202).

[0083] Based on the data acquired by the sensor input unit 94 and the data detected by the rotation speed detection unit 95, the first refrigerant state quantity calculation unit 202a (Figure 3) determines the first refrigerant density (p1), which is an estimated value of the density of the refrigerant drawn into the compressor, as the first refrigerant state quantity, and the second refrigerant state quantity calculation unit 202b (Figure 3) calculates the second refrigerant density (p2), which is an estimated value of the density of the refrigerant flowing through the outdoor expansion valve 29, as the second refrigerant state quantity from the acquired first refrigerant density (p1) (ST203).

[0084] The first refrigerant density (p1) can be determined using the suction temperature of the compressor 21 (the value detected by the suction temperature sensor 54). In this embodiment, the first refrigerant density (p1) is obtained based on a predetermined table T (see Figure 7) corresponding to the suction temperature, which is the temperature of the refrigerant drawn into the compressor 21, and the suction pressure, which is the pressure of the refrigerant drawn into the compressor 21.

[0085] Figure 7 shows an example of a table T illustrating the relationship between refrigerant density, suction pressure, and suction temperature. In this figure, the vertical axis represents suction pressure (gauge pressure), and the horizontal axis represents suction temperature. Table T is stored in database 220 and referenced when determining the first refrigerant density (p1). Alternatively, the first refrigerant density (p1) may be calculated using a function that calculates the refrigerant density from the suction temperature and suction pressure instead of using table T.

[0086] The second refrigerant density (p2) is calculated using the first refrigerant density (p1) obtained as described above, the rotational speed of the compressor 21, the exhaust volume of the compressor 21, the capacity coefficient of the outdoor expansion valve 29, and the pressure difference of the refrigerant between the inlet and outlet sides of the outdoor expansion valve 29.

[0087] In this embodiment, the second refrigerant density (p2) is calculated using the following equation (3), assuming that the first refrigerant mass flow rate (F1) and the second refrigerant mass flow rate (F2) described in the first embodiment are the same (equation (1) = (equation (2)). First refrigerant mass flow rate = Second refrigerant mass flow rate First refrigerant density × compressor exhaust volume × compressor rotation speed = Second refrigerant mass flow rate = volume coefficient × {(intermediate pressure - low pressure) / second refrigerant density} １／２ …(3)

[0088] Next, the information processing device 200 determines whether the second refrigerant density (p2) calculated as described above is less than or equal to the first threshold (Td1) (ST204). The first threshold (Td1) is set to be a predetermined amount less than the density when the dryness of the refrigerant is 0 (saturated liquid). This predetermined amount can be set, for example, based on the amount of refrigerant reduction that allows 80-90% of the target heating capacity to be achieved, and is determined in advance by experiment.

[0089] When the second refrigerant density (p2) is greater than the first threshold (Td1) (No in ST204), it is determined that there is no decrease in the amount of refrigerant and the process returns to ST201. On the other hand, when the second refrigerant density (p2) is less than or equal to the first threshold (Td1), it is determined whether or not the second refrigerant density (p2) is less than or equal to the second threshold (Td2) (ST205). The second threshold (Td2) can be set, for example, based on the amount of refrigerant that cannot achieve 70% or more of the target heating capacity, and is determined in advance by experiment.

[0090] As described above, according to this embodiment, similar to the first embodiment, during heating operation, it is possible to accurately determine whether there is a decrease or shortage in the amount of refrigerant using only the information that can be obtained on the outdoor unit 2 side, without using information from the indoor units 8a to 8c side.

[0091] Furthermore, in the above embodiment, not only is it determined whether or not there is a shortage of refrigerant, but also whether or not there is a decrease in the amount of refrigerant using a threshold (Td1), so that it is possible to identify in advance which air conditioning systems tend to have a shortage of refrigerant. As a result, necessary maintenance work such as refrigerant charging can be performed on the air conditioning system before the amount of refrigerant in the air conditioning system becomes insufficient, and the situation in which the air conditioning system stops operating due to a shortage of refrigerant can be prevented as much as possible.

[0092] 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.

[0093] For example, in the above embodiment, the information processing 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).

[0094] 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.

[0095] 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...Information processing device

Claims

1. An information processing device for managing the state of an outdoor unit of an air conditioning system having a compressor, an outdoor heat exchanger, and an outdoor expansion valve, comprising: a calculation unit that, when the refrigerant circuit is in a heating cycle, calculates a first refrigerant state quantity, which is an estimated value of the state quantity of the refrigerant on the refrigerant suction side of the compressor, based on the operating state quantity related to the drive of the compressor, and calculates a second refrigerant state quantity, which is an estimated value of the state quantity of the refrigerant flowing through the outdoor expansion valve, using the capacity coefficient of the outdoor expansion valve; and a determination unit that determines whether or not there has been a decrease in the amount of refrigerant, which is the amount of refrigerant circulating in the refrigerant circuit, by comparing the second refrigerant state quantity with the first refrigerant state quantity, or by comparing the second refrigerant state quantity with a predetermined reference value.

2. An information processing device according to claim 1, wherein the calculation unit calculates a first refrigerant mass flow rate, which is an estimated value of the mass flow rate of the refrigerant on the refrigerant suction side of the compressor, using the rotational speed of the compressor as the first refrigerant state quantity, and calculates a second refrigerant mass flow rate, which is an estimated value of the mass flow rate of the refrigerant flowing through the outdoor expansion valve, using the capacity coefficient of the outdoor expansion valve as the second refrigerant state quantity.

3. An information processing device according to claim 2, wherein the calculation unit further calculates the first refrigerant mass flow rate using the first refrigerant density, which is the density of the refrigerant drawn into the compressor, and the exhaust volume of the compressor.

4. An information processing device according to claim 2, wherein the calculation unit calculates the second refrigerant mass flow rate using the capacity coefficient of the outdoor expansion valve, the second refrigerant density which is the density of the liquid refrigerant flowing into the outdoor expansion valve, and the pressure difference of the refrigerant between the inlet side and the outlet side of the outdoor expansion valve.

5. An information processing device according to claim 4, wherein the calculation unit calculates a capacity coefficient corresponding to the opening degree from the opening degree of the outdoor expansion valve, and calculates the second refrigerant flow rate using the calculated capacity coefficient.

6. An information processing device according to any one of claims 2 to 5, wherein the determination unit determines that the amount of refrigerant is decreasing when the value obtained by dividing the second refrigerant mass flow rate by the first refrigerant mass flow rate is greater than or equal to a predetermined first threshold that is greater than 1.

7. An information processing device according to claim 6, wherein the determination unit determines that the amount of refrigerant is insufficient when the value obtained by dividing the second refrigerant mass flow rate by the first refrigerant mass flow rate is greater than or equal to a second threshold which is greater than the first threshold.

8. An information processing device according to claim 1, wherein the calculation unit calculates a first refrigerant density, which is an estimated value of the density of the refrigerant drawn into the compressor using the suction temperature of the compressor, as the first refrigerant state quantity, and calculates a second refrigerant density, which is an estimated value of the density of the refrigerant flowing through the outdoor expansion valve, as the second refrigerant state quantity, using the first refrigerant density.

9. An information processing device according to claim 8, wherein the calculation unit acquires the first refrigerant density based on a predetermined table corresponding to the intake temperature, which is the temperature of the refrigerant drawn into the compressor, and the intake pressure, which is the pressure of the refrigerant drawn into the compressor, and calculates the second refrigerant density using the acquired first refrigerant density, the rotational speed of the compressor, the exhaust volume of the compressor, the capacity coefficient of the outdoor expansion valve, and the pressure difference of the refrigerant between the inlet side and the outlet side of the outdoor expansion valve.

10. An information processing device according to claim 8 or 9, wherein the determination unit determines that the amount of refrigerant is decreasing when the second refrigerant density is less than or equal to a first threshold which is less by a predetermined amount than the density when the dryness of the refrigerant is 0, and generates a first alarm signal corresponding to the determination result.

11. An information processing device according to claim 10, wherein the determination unit determines that the amount of refrigerant is insufficient when the second refrigerant density is less than or equal to a second threshold which is less than the first threshold, and generates a second alarm signal corresponding to the determination result.

12. An air conditioning system comprising: an outdoor unit having a compressor, an outdoor heat exchanger and an outdoor expansion 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 an information processing device for managing the state of the air conditioning system, wherein the information processing device includes: a calculation unit that, when the refrigerant circuit is in a heating cycle, calculates a first refrigerant state quantity, which is an estimated value of the state quantity of the refrigerant on the refrigerant suction side of the compressor, based on an operating state quantity related to the driving of the compressor, and calculates a second refrigerant state quantity, which is an estimated value of the state quantity of the refrigerant flowing through the outdoor expansion valve, using a capacity coefficient of the outdoor expansion valve; and a determination unit that determines whether or not there has been a decrease in the amount of refrigerant, which is the amount of refrigerant circulating in the refrigerant circuit, by comparing the second refrigerant state quantity with the first refrigerant state quantity, or by comparing the second refrigerant state quantity with a predetermined reference value.

13. An air conditioning system according to claim 12, wherein the information processing device further comprises a control unit for controlling the compressor and the outdoor expansion valve.

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