AIR CONDITIONING AND CLIMATE CONTROL SYSTEM

Abstract

An air conditioning system (1) comprises a refrigerant circuit (200) comprising a compressor (30), a condenser (60), at least one expansion valve (65), and an evaporator (50), and is configured to circulate refrigerant, a control device (100) for controlling the refrigerant circuit, a receiver (70) in which liquid refrigerant is stored, wherein the receiver is configured to separate refrigerant flowing through the refrigerant circuit into liquid refrigerant and gaseous refrigerant, a first temperature sensor (91) for measuring a temperature of refrigerant flowing into the receiver, and a second temperature sensor (92) for measuring a temperature of refrigerant flowing out of the receiver. The receiver is arranged between the compressor and the evaporator.The control device calculates an amount of liquid refrigerant stored in the accumulator based on a first measurement result of the first temperature sensor and a second measurement result of the second temperature sensor.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an air conditioning system and an air conditioning system. BACKGROUND TO THE STATE OF THE ART

[0002] An air conditioner is designed to cool or heat the interior of a space to be conditioned by circulating refrigerant through a refrigerant circuit. Generally, the amount of refrigerant required for heating operation is smaller than that required for cooling operation. Therefore, the amount of refrigerant to be charged into the air conditioner's refrigerant circuit is determined based on the amount of refrigerant required during cooling operation. Excess refrigerant not used during heating operation is stored in a receiver located between a compressor and an evaporator, which are integrated into the refrigerant circuit.An operator adjusting or inspecting the air conditioning system can determine whether the amount of refrigerant circulating through the refrigerant circuit is adequate or not by checking the amount of refrigerant stored in the receiver.

[0003] WO2019 / 065242 (PTL 1) discloses a liquid level sensor for detecting a liquid level of refrigerant stored in a receiver. This liquid level sensor is configured to measure a surface temperature of the receiver using a plurality of temperature sensors arranged in a height direction of the receiver. The receiver is heated by a heater, which detects the liquid level of the refrigerant stored in the receiver based on a difference in temperature change in accordance with a state of the refrigerant in the receiver. REFERENCE LISTPATENT LITERATURE

[0004] PTL 1: WO2019 / 065242 SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0005] The liquid level sensor described in WO2019 / 065242 can detect the amount of refrigerant stored in the receiver. However, the heater and the numerous temperature sensors must be specially housed in the receiver, increasing costs. Therefore, a technology was required that allows an operator installing, adjusting, or inspecting an air conditioning system to check the amount of refrigerant stored in the receiver more cost-effectively.

[0006] The present disclosure has been made to solve the above problem, and an object thereof is to provide a technique that enables an operator to check an amount of refrigerant stored in a receiver more cost-effectively. SOLUTION TO THE PROBLEM

[0007] An air conditioning system according to the present disclosure comprises a refrigerant circuit comprising a compressor, a condenser, at least one expansion valve, and an evaporator, wherein the refrigerant circuit is configured to circulate refrigerant; a control device configured to control the refrigerant circuit; a receiver in which liquid refrigerant is stored, wherein the receiver is configured to separate refrigerant flowing through the refrigerant circuit into liquid refrigerant and gaseous refrigerant; a first temperature sensor configured to measure a temperature of the refrigerant flowing into the receiver; and a second temperature sensor configured to measure a temperature of the refrigerant flowing out of the receiver. The receiver is arranged between the compressor and the evaporator.The control device calculates an amount of the liquid refrigerant stored in the receiver based on a first measurement result of the first temperature sensor and a second measurement result of the second temperature sensor.

[0008] An air conditioning system according to the present disclosure includes the air conditioning system described above and a user device for issuing a notification of the amount of liquid refrigerant stored in the accumulator, the amount being calculated by the air conditioning system. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0009] Since the air conditioner according to the present disclosure can calculate the amount of liquid refrigerant stored in the receiver based on the temperature of the refrigerant flowing into the receiver and the temperature of the refrigerant flowing out of the receiver, an operator can check the amount of liquid refrigerant stored in the receiver at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a configuration of an air conditioner and an air conditioning system according to a first embodiment. Fig. 2 is a pressure-enthalpy diagram of a refrigeration cycle in the air conditioner according to the first embodiment. Fig. 3 is a diagram illustrating an internal configuration of a collector according to the first embodiment. Fig. 4 is a time chart illustrating the state change in the refrigerant cycle when the air conditioner according to the first embodiment performs a refrigerant amount detection process. Fig. 5 is a graphical representation of a change in the liquid level of the liquid refrigerant in the receiver with respect to a difference between a superheat degree of the refrigerant flowing into the receiver and the superheat degree of the refrigerant flowing out of the receiver. Fig. 6 is a flowchart illustrating the refrigerant amount detection process performed by the air conditioner according to the first embodiment. Fig. 7 is a diagram showing a configuration of the air conditioner and the air conditioning system according to a second embodiment. DESCRIPTION OF THE EMBODIMENTS

[0010] An embodiment of the present disclosure will be described in detail below with reference to the drawings. Although a variety of embodiments will be explained below, a combination of the features explained in the embodiments is originally intended. In the drawings, the same reference numerals are assigned to the same or corresponding parts, and their description will not be repeated. First embodiment.

[0011] An air conditioning system 1 and an air conditioning system 1000 according to a first embodiment will be described with reference to Fig. 1 described. Fig. 1 is a diagram showing a configuration of an air conditioner 1 and an air conditioning system 1000 according to the first embodiment. Fig. 1 functionally shows the connection relationship and an arrangement configuration of elements in the air conditioner 1 and does not necessarily show the arrangement in a physical space.

[0012] As in Fig. 1, the air conditioning system 1000 comprises an air conditioning system 1 and a user device 500.

[0013] The air conditioning system 1 comprises a refrigerant circuit 200 and a control device 100. The refrigerant circuit 200 comprises an outdoor unit 300 and an indoor unit 400. The outdoor unit 300 and the indoor unit 400 are connected to each other by an extension line 21 and an extension line 22, and refrigerant circulates between the outdoor unit 300 and the indoor unit 400.

[0014] The outdoor unit 300 is generally set in the outdoor area not to be air-conditioned and comprises a four-way valve 40, a compressor 30, an outdoor heat exchanger 50 and an outdoor fan 51.

[0015] The four-way valve 40 includes a connecting port 41, a connecting port 42, a connecting port 43, and a connecting port 44. The connecting port 41 of the four-way valve 40 is connected to an inlet 31 of the compressor 30 via a line 18 and a line 19. The connecting port 42 of the four-way valve 40 is connected to the outdoor heat exchanger 50 via a line 17. The connecting port 43 of the four-way valve 40 is connected to an outlet 32 ​​of the compressor 30 via a line 11. The connecting port 44 of the four-way valve 40 is connected to the indoor unit 400 via a line 12 and an extension line 21. The four-way valve 40 is configured to switch an internal communication state under the control of the control device 100.

[0016] The compressor 30 is configured to be activated and deactivated during operation under the control of the control device 100, and further to change the rotational speed. The control device 100 changes the drive frequency of the compressor 30 to any desired drive frequency by controlling the compressor 30. The number of revolutions, i.e., the rotational speed per unit time, of the compressor 30 changes with the change in the drive frequency, and thus the discharge amount of the refrigerant also changes. Various types of compressors can be used as the compressor 30, and for example, a scroll-type compressor, a rotary-type compressor, or a screw-type compressor can be used as the compressor 30.

[0017] The outdoor heat exchanger 50 performs heat exchange between the air drawn in from the outside by the outdoor fan 51 (i.e., the outside air) and the refrigerant. One end of the outdoor heat exchanger 50 is connected to the connecting port 42 of the four-way valve 40 via the line 17. The other end of the outdoor heat exchanger 50 is connected to the indoor unit 400 via a line 16 and an extension line 22.

[0018] The outdoor fan 51 is configured to be activated and deactivated during operations under the control of the controller 100, and also to change its rotational speed. The controller 100 changes a drive frequency of the outdoor fan 51 to any desired drive frequency by controlling the outdoor fan 51. The number of revolutions, i.e., the rotational speed per unit time, of the outdoor fan 51 changes with the drive frequency, and thus the amount of air sent to the outdoor heat exchanger 50 also changes.

[0019] The indoor unit 400 is generally set in an indoor space to be air-conditioned and includes an indoor heat exchanger 60, an indoor fan 61, and an indoor expansion valve 65.

[0020] The indoor heat exchanger 60 performs heat exchange between the air drawn in by the indoor fan 61 and the refrigerant. One end of the indoor heat exchanger 60 is connected to the outdoor unit 300 via a pipe 13 and an extension pipe 21. The other end of the indoor heat exchanger 60 is connected to the indoor expansion valve 65 via a pipe 14.

[0021] The indoor fan 61 is configured to be activated and deactivated during operations under the control of the controller 100, and also to change its rotational speed. The controller 100 changes a drive frequency of the indoor fan 61 to any desired drive frequency by controlling the indoor fan 61. The number of revolutions, i.e., the rotational speed per unit time, of the indoor fan 61 changes with the change in the drive frequency, and thus the amount of air sent to the indoor heat exchanger 60 also changes.

[0022] The indoor expansion valve 65 is, for example, an electronic expansion valve whose opening is adjusted under the control of the controller 100. The indoor expansion valve 65 reduces the pressure of the incoming refrigerant and allows the refrigerant obtained by the pressure reduction to flow out. The controller 100 can adjust the amount of pressure reduction of the refrigerant by adjusting the opening of the indoor expansion valve 65. One end of the indoor expansion valve 65 is connected to the indoor heat exchanger 60 via a conduit 14. The other end of the indoor expansion valve 65 is connected to the indoor unit 300 via a conduit 15 and an expansion conduit 22.

[0023] The control device 100 includes a control unit 101 and a mass storage device 102. The control device 100 can communicate with each actuator of the refrigerant cycle 200, such as the compressor 30, the indoor expansion valve 65, the four-way valve 40, the outdoor fan 51, and the indoor fan 61, to control each actuator of the refrigerant cycle 200. The control device 100 can be mounted on one of the outdoor unit 300 and the indoor unit 400, or can be separate from the outdoor unit 300 and the indoor unit 400.

[0024] The control unit 101 is a computing unit for controlling each actuator of the refrigerant cycle 200 by executing various programs. The control unit 101 is implemented by a computer such as a processor. The processor is realized, for example, by a microcontroller, a central processing unit (CPU), a microprocessor unit (MPU), or the like. Although the processor performs functions to perform various types of processing by executing a program, some or all of these functions may be performed by a dedicated hardware circuit such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).The term "processor" is not limited to a processor in the narrow sense that performs processing according to a stored program architecture, such as a CPU or MPU, but can also include a hard-wired circuit, an ASIC, or an FPGA. Therefore, a processor can also be understood as a processing circuit whose processing is defined in advance by computer-readable code and / or a hard-wired circuit. The processor can be implemented by a single chip or by a plurality of chips. Furthermore, the processor and the associated processing circuit can be implemented by a plurality of computers connected to each other via cables or wirelessly via a local area network or a wireless network.The processor and associated processing circuitry may be implemented by a cloud computer that performs a remote computation based on input data and outputs the result of the computation to another device located at a remote location.

[0025] The mass storage 102 provides a storage area in which program code, random access memory, or the like is stored during the execution of various programs by the processor of the control unit 101. The mass storage 102 may be one or more non-transitory computer-readable media. Examples of the mass storage 102 include volatile memory such as dynamic random access memory (DRAM) and static random access memory (SRAM), or non-volatile memory such as read-only memory (ROM) and flash memory. The mass storage 102 may be formed from one or more computer-readable storage media. Examples of the mass storage 102 include a storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The control unit 101 controls each actuator of the refrigerant circuit 200 by executing a program stored in the mass storage 102.

[0026] The user device 500 is configured to communicate with the control device 100 via a network. The user device 500 is an information terminal used by a user, such as an operator. The user device 500 may be implemented by a general-purpose computer or a dedicated computer for controlling the air conditioning system 1. The user device 500 may, for example, be an information terminal that performs prescribed information processing, such as a desktop personal computer (PC), a laptop, a smartphone, a smartwatch, a wearable device, a tablet PC, and a remote controller present in a building. The user, such as an operator, can use the user device 500 to control the air conditioning system 1 or can view the data received from the air conditioning system 1 on a display (not shown) of the user terminal 500.

[0027] The air conditioning system 1 further comprises a pressure sensor 81, a pressure sensor 82, a temperature sensor 91, a temperature sensor 92, a temperature sensor 93, a temperature sensor 94 and a temperature sensor 95.

[0028] The pressure sensor 81 is located between an inlet side of the accumulator 70 and the evaporator, and measures a pressure of the refrigerant flowing from the evaporator into the accumulator 70. A refrigerant pressure P1 measured by the pressure sensor 81 is transmitted to the control device 100.

[0029] The pressure sensor 82 is located between the outlet 32 ​​of the compressor 30 and the condenser and measures the pressure of the refrigerant discharged from the compressor 30. A refrigerant pressure P2 measured by the pressure sensor 82 is transmitted to the control device 100.

[0030] The temperature sensor 91 is located between the inlet side of the receiver 70 and the evaporator and measures a temperature of the refrigerant flowing into the receiver 70. A refrigerant temperature T1 measured by the temperature sensor 91 is transmitted to the control device 100. The temperature sensor 91 is an exemplary "first temperature sensor." A refrigerant temperature T1 measured by the temperature sensor 91 is an exemplary "first measurement result."

[0031] The temperature sensor 92 is located between an outlet side of the receiver 70 and an inlet 31 of the compressor 30, and measures a temperature of the refrigerant flowing out of the receiver 70. A refrigerant temperature T2 measured by the temperature sensor 92 is transmitted to the control device 100. The temperature sensor 92 is an exemplary "second temperature sensor." A refrigerant temperature T2 measured by the temperature sensor 92 is an exemplary "second measurement result."

[0032] The temperature sensor 93 is located between the outlet 32 ​​of the compressor 30 and the condenser and measures the temperature of the refrigerant discharged from the compressor 30. A refrigerant temperature T3 measured by the temperature sensor 93 is transmitted to the control device 100.

[0033] The temperature sensor 94 is located between the indoor heat exchanger 60 and the indoor expansion valve 65 and measures a temperature of the refrigerant flowing out of the indoor heat exchanger 60. A refrigerant temperature T4 measured by the temperature sensor 94 is transmitted to the control device 100.

[0034] The temperature sensor 95 is arranged in or on the outdoor heat exchanger 50 and measures an outside air temperature. The outside air temperature T5 measured by the temperature sensor 95 is transmitted to the control device 100.

[0035] The air conditioner 1 configured as described above is controlled to be in one of several types of operation modes, including a heating operation mode in which an interior is heated and a cooling operation mode in which the interior is cooled.

[0036] First, the operation of the air conditioner 1 in the heating mode is explained. As in Fig. 1, the communication state in the four-way valve 40 in the heating operation mode is such that the communication port 41 communicates with the communication port 42, and the communication port 43 communicates with the communication port 44. In other words, in the heating operation mode, the inlet 31 of the compressor 30 is connected to one side of the outdoor heat exchanger 50, and the outlet 32 ​​of the compressor 30 is connected to one side of the indoor heat exchanger 60.

[0037] Compressor 30 draws in low-temperature, low-pressure gaseous refrigerant flowing in from outdoor heat exchanger 50 and increases the pressure of the gaseous refrigerant by compressing the drawn-in gaseous refrigerant. Compressor 30 discharges high-temperature, high-pressure gaseous refrigerant obtained by compression to indoor heat exchanger 60.

[0038] In the heating mode, the indoor heat exchanger 60 functions as the condenser. In the indoor heat exchanger 60, the high-temperature, high-pressure gaseous refrigerant from the compressor 30 exchanges heat with the air drawn from the indoor space by the indoor fan 61. The gaseous refrigerant, which has radiated heat to the air as a result of this heat exchange, is condensed in the indoor heat exchanger 60 and transformed into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant obtained in the indoor heat exchanger 60 flows out to the indoor expansion valve 65. The air that has absorbed heat from the gaseous refrigerant in the indoor heat exchanger 60 is sent back into the indoor space. The indoor space is thereby heated.

[0039] The indoor expansion valve 65 reduces the pressure of the high-temperature and high-pressure liquid refrigerant from the indoor heat exchanger 60. The low-temperature and low-pressure gas-liquid two-phase refrigerant obtained in the indoor expansion valve 65 flows out to the outdoor heat exchanger 50.

[0040] In the heating mode, the outdoor heat exchanger 50 functions as the evaporator. In the outdoor heat exchanger 50, heat exchange occurs between the low-temperature, low-pressure gas-liquid two-phase refrigerant from the indoor expansion valve 65 and the air drawn in from the outside by the outdoor fan 51. The gas-liquid two-phase refrigerant, which has absorbed heat from the air as a result of this heat exchange, evaporates in the outdoor heat exchanger 50 and becomes low-temperature, low-pressure gaseous refrigerant. The low-temperature, low-pressure gaseous refrigerant obtained in the outdoor heat exchanger 50 flows out to the compressor 30.

[0041] In heating mode, the refrigerant flows sequentially through the compressor 30, the indoor heat exchanger 60 (condenser), the indoor expansion valve 65 and the outdoor heat exchanger 50 (evaporator).

[0042] Now, operation of the air conditioner 1 in cooling mode will be explained. As in Fig. 1, the communication state in the four-way valve 40 in the cooling operation mode is such that the communication port 41 communicates with the communication port 44, and the communication port 42 communicates with the communication port 43. In other words, in the cooling operation mode, the inlet 31 of the compressor 30 is connected to one side of the indoor heat exchanger 60, and the outlet 32 ​​of the compressor 30 is connected to the outdoor heat exchanger 50 side.

[0043] The compressor 30 draws in low-temperature, low-pressure gaseous refrigerant from the outdoor heat exchanger 60 and increases the pressure of the gaseous refrigerant by compressing the drawn-in gaseous refrigerant. The compressor 30 discharges the high-temperature, high-pressure gaseous refrigerant obtained by compression to the outdoor heat exchanger 50.

[0044] In cooling mode, the outdoor heat exchanger 50 functions as the condenser. The outdoor heat exchanger 50 facilitates heat exchange between the high-temperature, high-pressure gaseous refrigerant from the compressor 30 and the air drawn in from the outside by the indoor fan 51. The gaseous refrigerant, which has radiated heat to the air as a result of this heat exchange, is condensed in the outdoor heat exchanger 50 and transformed into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant obtained in the outdoor heat exchanger 50 flows out to the indoor expansion valve 65.

[0045] The indoor expansion valve 65 reduces the pressure of the high-temperature and high-pressure liquid refrigerant from the outdoor heat exchanger 50. The low-temperature and low-pressure gas-liquid two-phase refrigerant obtained by depressurizing the indoor expansion valve 65 flows out to the indoor heat exchanger 60.

[0046] In cooling mode, the indoor heat exchanger 60 functions as the evaporator. The indoor heat exchanger 60 facilitates heat exchange between the low-temperature, low-pressure gas-liquid two-phase refrigerant from the indoor expansion valve 65 and the air drawn from the outside by the indoor fan 61. The gas-liquid two-phase refrigerant, which has absorbed heat from the air as a result of this heat exchange, evaporates in the indoor heat exchanger 60 and becomes low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant obtained in the indoor heat exchanger 60 flows out to the compressor 30. The air, from which heat has been absorbed by the gas refrigerant in the indoor heat exchanger 60, is sent back into the indoor space. The indoor space is thereby cooled.

[0047] In cooling mode, the refrigerant flows sequentially through the compressor 30, the outdoor heat exchanger 50 (condenser), the indoor expansion valve 65 and the indoor heat exchanger 60 (evaporator).

[0048] Fig. Fig. 2 is a pressure-enthalpy diagram of a refrigeration cycle in the air conditioner 1 according to the first embodiment. In the pressure-enthalpy diagram in Fig. 2, the ordinate represents the absolute pressure p and the abscissa represents the specific enthalpy h. The points a1, a2 and a3 in Fig. 2 each indicate a state of the refrigerant between the outlet 32 ​​of the compressor 30 and the condenser. Point b indicates the state of the refrigerant between the condenser and the indoor expansion valve 65. Point c indicates the state of the refrigerant between the indoor expansion valve 65 and the evaporator. Points d1, d2, and d3 each indicate the state of the refrigerant between the evaporator and the inlet 31 of the compressor 30.

[0049] In the refrigeration cycle, the change in state of the refrigerant from points d1, d2, and d3 to the respective points a1, a2, and a3 represents a change in state of the refrigerant resulting from its flow through the compressor 30. The change in state of the refrigerant from points a1, a2, and a3 to point b represents the change in state of the refrigerant resulting from the refrigerant flowing through the condenser. The change in state of the refrigerant from point b to point c represents the change in state of the refrigerant resulting from the refrigerant flowing through the indoor expansion valve 65. The change in state of the refrigerant from point c to points d1, d2, and d3 represents the change in state of the refrigerant resulting from the refrigerant flowing through the evaporator.

[0050] Generally, in the air conditioning system 1, the amount of refrigerant required for heating operation is smaller than the amount of refrigerant required for cooling operation. Therefore, the amount of refrigerant to be charged into the refrigerant circuit 200 of the air conditioning system 1 is determined based on the amount of refrigerant required during cooling operation, and in heating operation, there may be a surplus of refrigerant that is not used in heating operation. The air conditioning system 1 also includes a receiver 70 between the compressor 30 and the evaporator, which is configured to store a surplus of refrigerant in the receiver 70. As shown in Fig. As shown in Figure 1, in the heating mode, the collector 70 is arranged between the compressor 30 and the outdoor heat exchanger 50. In the cooling mode, the collector 70 is arranged between the compressor 30 and the indoor heat exchanger 60.

[0051] Fig. 3 is a diagram illustrating an internal configuration of the collector 70 according to the first embodiment. As shown in Fig. 3, the collector 70 comprises a container 71, an inlet line 72 and an outlet line 73.

[0052] The inlet line 72 is configured to be connected to the line 18 connected to the evaporator side and is configured to introduce refrigerant flowing from the evaporator through the line 18 into the tank 71. Of the refrigerant introduced through the inlet line 72, the liquid refrigerant is stored in a lower part of the tank 71, and the gaseous refrigerant remains in an upper part of the tank 71.

[0053] The discharge line 73 is configured to be connected to the line 19 connected to one side of the compressor 30 and is configured to introduce refrigerant stored in the tank 71 to the inlet 31 of the compressor 30 via a line 19. The discharge line 73 is U-shaped and includes a gas inlet 73a through which the gaseous refrigerant remaining in the upper part of the tank 71 is to be sucked in, and a liquid inlet 73b through which the liquid refrigerant stored in the lower part of the tank 71 is to be sucked in. The refrigerant gas sucked in through the gas inlet 73a flows through the discharge line 73 and flows to the inlet 31 of the compressor 30. The liquid refrigerant sucked in through the liquid inlet 73b passes through the discharge line 73 and flows out to the inlet 31 of the compressor 30.Since a diameter of the liquid inlet 73b is smaller than a diameter of the discharge line 73, only a small amount of liquid refrigerant is sucked through the liquid inlet 73b.

[0054] In the accumulator 70 configured as described above, of the refrigerant that has flowed from the evaporator through the line 18, liquid refrigerant is stored in the lower part of the tank 71, and gaseous refrigerant remains in the upper part of the tank 71, so that refrigerant flowing through the refrigerant circuit 200 can be separated into liquid refrigerant and gaseous refrigerant, and liquid refrigerant can be stored in the tank 71. The liquid refrigerant stored in the tank 71 flows in very small amounts through the liquid inlet 73b disposed therein into the outlet line 73 and is returned through the outlet line 73 to the inlet 31 of the compressor 30.

[0055] The accumulator 70 is also abbreviated to "ACC" below. A liquid level of the liquid refrigerant stored in the tank 71 of the accumulator 70 is also referred to as the "ACC liquid level." The amount of liquid refrigerant stored in the tank 71 of the accumulator 70 is also referred to as the "ACC liquid refrigerant amount." The return of the liquid refrigerant stored in the tank 71 to the discharge line 73 through the liquid inlet 73b is also referred to as "liquid return."

[0056] The operator can charge the refrigerant circuit 200 with refrigerant when setting up the air conditioner 1, or additionally charge the refrigerant circuit 200 of the already installed air conditioner 1 with refrigerant. At this time, the operator can check the amount of liquid refrigerant stored in the receiver 70 to determine whether or not the refrigerant circuit 200 is filled with an adequate amount of refrigerant. Furthermore, the operator can check the amount of liquid refrigerant in the receiver 70 in the already installed air conditioner 1 to determine whether or not a refrigerant leak has occurred in the refrigerant circuit 200. Therefore, when setting up, adjusting, or inspecting the air conditioner 1, the operator must check the amount of liquid refrigerant stored in the receiver 70.

[0057] A method of detecting the ACC liquid level based on a difference in temperature change in accordance with a state of the refrigerant in the accumulator 70 by heating the accumulator 70 with a heater (not shown) and measuring a surface temperature of the accumulator 70 with a plurality of temperature sensors (not shown) provided in a height direction of the accumulator 70 is available as a method for checking the amount of liquid refrigerant stored in the accumulator 70. For such a method, the heater and the plurality of temperature sensors should be provided specifically in the accumulator 70, and costs are reduced.

[0058] The air conditioning system 1 according to the first embodiment is then configured to enable a more cost-effective check of the amount of liquid refrigerant stored in the accumulator 70 by performing a refrigerant amount detection process.

[0059] Fig. 4 is a time chart illustrating the state change in the refrigeration cycle when the air conditioner 1 according to the first embodiment performs the refrigerant amount detection process. Fig. 4 shows the state change in the refrigeration cycle when the refrigerant amount detection process is performed in the heating operation mode.

[0060] As in Fig. 4, the control device 100 in the air conditioning system 1 controls the refrigerant circuit 200 in a first operating mode after commissioning, and thereafter controls the refrigerant circuit 200 in a second operating mode.

[0061] Fig. Figure 4(A) shows how the drive frequency of the compressor 30 (hereinafter also referred to as "compressor frequency"), the number of revolutions per unit time of the outdoor fan 51 (hereinafter also referred to as "outdoor fan speed"), and the opening of the indoor expansion valve 65 (hereinafter also referred to as "LEV opening") change during startup, during the first operation mode, and during the second operation mode. The compressor frequency, the outdoor fan speed, and the LEV opening are controlled by the controller 100.

[0062] Fig. Figure 4(B) shows how a subcooling degree at a condenser outlet (hereinafter also referred to as “condenser outlet SC”), a superheating degree at an ACC inlet (hereinafter also referred to as “ACC inlet SH”), and a superheating degree at an ACC outlet (hereinafter also referred to as “ACC outlet SH”) change during startup, during the first operation mode, and during the second operation mode.

[0063] As in Fig. As shown in Figure 2, the condenser outlet SC can be calculated by subtracting a refrigerant temperature at the condenser outlet from a condensing temperature. For example, the controller 100 obtains the pressure P2 of the refrigerant discharged from the compressor 30 from the pressure sensor 82 and calculates a saturation temperature of the refrigerant as the condensing temperature based on the obtained refrigerant pressure P2. Furthermore, the controller 100 obtains the temperature T4 of the refrigerant flowing out of the indoor heat exchanger 60, the condenser, from the temperature sensor 94. The controller 100 can calculate the condenser outlet SC by subtracting the refrigerant temperature T4 from the saturation temperature calculated as the condensing temperature.

[0064] As in Fig. As shown in Figure 2, the ACC inlet SH can be calculated by subtracting an evaporating temperature from the refrigerant temperature at the ACC inlet. For example, the controller 100 obtains the temperature T1 of the refrigerant flowing into the accumulator 70 from the temperature sensor 91. Furthermore, the controller 100 obtains the pressure P1 of the refrigerant flowing out of the outdoor heat exchanger 50, which is the evaporator, from the pressure sensor 81 and calculates the saturation temperature of the refrigerant as the evaporating temperature based on the obtained refrigerant pressure P1. The controller 100 can calculate the ACC inlet SH by subtracting the evaporating temperature calculated based on the refrigerant pressure P1 from the refrigerant temperature T1. The ACC inlet SH is an example of the "first superheat degree."

[0065] As in Fig. As shown in Figure 2, the ACC outlet SH can be calculated by subtracting the evaporation temperature from the refrigerant temperature at the ACC outlet. Furthermore, the controller 100 obtains the temperature T2 of the refrigerant flowing out of the receiver 70 from the temperature sensor 92. For example, the controller 100 obtains the pressure P1 of the refrigerant flowing out of the outdoor heat exchanger 50, which is the evaporator, from the pressure sensor 81 and calculates the saturation temperature of the refrigerant as the evaporation temperature based on the obtained refrigerant pressure P1. The controller 100 can calculate the ACC outlet SH by subtracting the evaporation temperature calculated based on the refrigerant pressure P1 from the refrigerant temperature T2. The ACC outlet SH is an example of the "second superheat degree."

[0066] Fig. Figure 4(C) shows how the evaporating temperature and the condensing temperature change during start-up, during the first operating mode, and during the second operating mode.

[0067] Fig. Figure 4(C) shows how the ACC liquid refrigerant amount changes during startup, during the first operating mode, and during the second operating mode.

[0068] When the control device 100 in the air conditioning system 1 controls the refrigerant circuit 200 in the first operating mode, the refrigerant circuit enters a stable state. Specifically, as shown in Fig. As shown in Figure 4(A), in the first operation mode, the air conditioner 1 sets the compressor frequency to a prescribed value so that the condensing temperature is constant, sets the outdoor fan speed to a prescribed value so that the evaporating temperature is constant, and sets the LEV opening to a prescribed value so that the condenser outlet SC is constant. As shown in Fig. 4(B), in such a first operation mode, a difference (hereinafter also referred to as "SH difference") between the ACC inlet SH and the ACC outlet SH becomes smaller than a prescribed value (for example, a value greater than 0). More specifically, in the first operation mode, the SH difference becomes 0 or nearly 0. In other words, in the first operation mode, the ACC inlet SH and the ACC outlet SH become equal or substantially equal. As shown in Fig. As shown in Figure 4(D), the amount of ACC liquid refrigerant also does not change significantly in the first operating mode.

[0069] While the refrigeration cycle is in the stable state in the first operation mode, the SH difference and the ACC liquid refrigerant amount are less likely to change, so that the air conditioning system 1 is unable to detect the ACC liquid refrigerant amount itself based on the pressure and temperature of the refrigerant flowing into or out of the receiver 70, that is, the refrigerant pressure P1 and the refrigerant temperatures T1 and T2.

[0070] In the air conditioner 1, the control device 100 then controls the refrigerant cycle 200 in the first operation mode to bring the refrigeration cycle into the stable state, and thereafter controls the refrigerant cycle 200 in the second operation mode to intentionally change the state of the refrigeration cycle to bring the refrigeration cycle into a transient state.

[0071] Specifically, as in Fig. As shown in Figure 4(A), in the second operation mode, the air conditioner 1 changes the compressor frequency so as to set the compressor frequency in the second operation mode to be lower than the compressor frequency in the first operation mode. For example, the air conditioner 1 minimizes the compressor frequency in the second operation mode. In the second operation mode, the air conditioner 1 changes the LEV opening so as to set the LEV opening in the second operation mode to be smaller than the LEV opening in the first operation mode. In contrast, in the second operation mode, the air conditioner 1 does not change the speed of the outdoor fan to set an air flow volume of the outdoor fan 51 in the second operation mode to be equal to the air flow volume of the outdoor fan 51 in the first operation mode. The speed of the outdoor fan in this case can be a maximum number of revolutions.

[0072] As in Fig. As can be seen in Figure 4(B), when the air conditioner 1 is controlled in the second operation mode, the ACC inlet AH becomes higher than the ACC outlet SH, and the SH difference is generated. In other words, when the air conditioner 1 is controlled in the second operation mode, the SH difference becomes equal to or greater than a prescribed value (for example, a value greater than 0). Furthermore, as shown in Fig. As shown in Figure 4(D), the ACC liquid refrigerant amount increases.

[0073] The reason why the SH difference described above is generated in the second operating mode is explained. When the compressor frequency is lowered and the LEV opening is reduced in the second operating mode compared to the steady state in the first operating mode, the amount of refrigerant flowing to the evaporator decreases. Since the speed of the outdoor fan in the evaporator remains unchanged, the gasification of the refrigerant in the evaporator is accelerated compared to the first operating mode. The superheat gas generated by the gasification in the evaporator flows into the receiver 70. Consequently, the refrigerant temperature at the ACC inlet temporarily rises. For example, as in Fig. 2, the refrigerant temperature at the ACC inlet in the first operating mode is around the evaporation temperature, the refrigerant temperature at the ACC inlet in the second operating mode rises to a value corresponding to point d1.

[0074] In the receiver 70, however, mixed refrigerant, which is a mixture of gaseous refrigerant drawn through the gas inlet 73a and liquid refrigerant drawn through the liquid inlet 73b, flows out to the compressor 30 through the discharge line 73 as a result of liquid recirculation. The temperature of the mixed refrigerant is lowered by mixing with the gaseous refrigerant, and the liquid refrigerant has a lower temperature than the gaseous refrigerant. In other words, the larger the returned amount of liquid refrigerant [kg / h], the lower the refrigerant temperature at the ACC outlet becomes, and the smaller the returned amount of liquid refrigerant, the higher the refrigerant temperature at the ACC outlet becomes.In addition, the higher the ACC liquid level or the higher the refrigerant flow rate in the discharge line 73, the larger the amount of returned liquid refrigerant becomes, and the lower the ACC liquid level or the lower the refrigerant flow rate in the discharge line 73, the smaller the amount of returned liquid refrigerant becomes. In other words, the higher the ACC liquid level or the higher the refrigerant flow rate in the discharge line 73, the lower the refrigerant temperature at the ACC outlet becomes, and the lower the ACC liquid level or the lower the refrigerant flow rate in the discharge line 73, the higher the refrigerant temperature at the ACC outlet becomes. As shown in FIG. Fig. 2, for example, in the second operating mode, the refrigerant temperature at the ACC outlet decreases from a value corresponding to point d1 to a value corresponding to point d2 or point d3 according to the returned amount of liquid refrigerant.

[0075] Since the air conditioning system 1 is thus controlled in the second operation mode, a difference between the refrigerant temperature at the ACC inlet and the refrigerant temperature at the ACC outlet can be generated depending on the amount of returned liquid refrigerant, that is, the ACC liquid level. Furthermore, as described above, the ACC inlet SH can be calculated by subtracting the evaporation temperature from the refrigerant temperature at the ACC inlet, and the ACC outlet SH can be calculated by subtracting the evaporation temperature from the refrigerant temperature at the ACC outlet. Since the same evaporation temperature is used to calculate the ACC inlet SH and the ACC outlet SH, the SH difference between the ACC inlet SH and the ACC outlet SH is proportional to a difference between the ACC inlet refrigerant temperature T1 and the ACC outlet refrigerant temperature T2.When the air conditioner 1 is thus controlled into the second operating mode as shown in . Fig. As shown in Figure 4(B), the SH difference is generated by the difference between the refrigerant temperature T1 at the ACC inlet and the refrigerant temperature T2 at the ACC outlet.

[0076] The relationship between the SH difference and the ACC fluid level is determined using Fig. 5 described. Fig. 5 is a graphical representation of the change in the liquid level (ACC liquid level) of the liquid refrigerant in the receiver 70 with respect to a difference (SH difference) between the superheat degree (ACC inlet SH) of the refrigerant flowing into the receiver 70 and the superheat degree (ACC outlet SH) of the refrigerant flowing out of the receiver 70.

[0077] As in Fig. As can be seen in Figure 5, the lower the ACC liquid level, the higher the refrigerant temperature at the ACC outlet, and thus the SH difference becomes smaller. Conversely, the higher the ACC liquid level, the lower the refrigerant temperature at the ACC outlet, and thus the greater the SH difference.

[0078] Furthermore, the change in the ACC liquid level with respect to such a SH difference varies depending on the compressor frequency. Specifically, the lower the compressor frequency, the smaller the change in the ACC liquid level with respect to the SH difference. There is an upper limit to the ACC liquid level, which depends on the volume of the reservoir 71. Therefore, since the compressor frequency is lower, a range can be ensured in which a change in the ACC liquid level with respect to the SH difference is detected.

[0079] As in Fig. For example, as shown in Figure 5, in an example where the compressor frequency is set to f1, the change in the ACC liquid level with respect to the SH difference is smaller than in an example where the compressor frequency is set to f2, which is higher than f1. In the example where the compressor frequency is set to f2, the ACC liquid level can be detected only in a range where the SH difference is between 0 and 6°C, while in the example where the compressor frequency is set to f1, the ACC liquid level can be detected in a range where the SH difference is between 0 and 10°C.

[0080] Therefore, when the air conditioner 1 lowers the compressor frequency in the second operation mode, it can minimize the compressor frequency to ensure a wider range within which a change in the ACC liquid level is detected with respect to the SH difference.

[0081] Thus, in the air conditioning system 1, the control device 100 controls the refrigerant circuit 200 in the second operation mode to generate the SH difference, and can then detect the ACC liquid level from the SH difference by referring to data on the change of the ACC liquid level with respect to the SH difference, as shown in Fig. 5. The controller 100 can calculate the amount of liquid refrigerant stored in the tank 71 of the accumulator 70 based on the detected ACC liquid level and a shape, volume, or the like of the tank 71 stored in advance in the mass storage 102.

[0082] If the condenser outlet SC is greater than 0, liquid refrigerant also remains in the condenser. The controller 100 is then configured to calculate an amount of liquid refrigerant remaining in the condenser, excluding the liquid refrigerant stored in the receiver 70, based on the liquid-phase area ratio A. L %.

[0083] The liquid phase area ratio A L % represents the volume ratio of the liquid phase to the total volume of the condenser and is an indicator obtained by correcting the condenser outlet SC with the outside air temperature, the discharge enthalpy of the compressor 30, and the specific heat of the liquid refrigerant at constant pressure. Specifically, the control device 100 calculates the liquid phase area ratio A. L % according to the following expression (1). AL%= -Ln(1-SC / dTc)*dTc*CPr / Δhcon

[0084] In expression (1), SC stands for the capacitor outlet SC. dT c represents the difference between the outside air temperature T5 measured by temperature sensor 95 and the condensation temperature. C Pr stands for the specific heat of the liquid refrigerant at constant pressure. Δh con represents the difference between the enthalpy of the refrigerant at the condenser inlet and the enthalpy of the refrigerant at the condenser outlet.

[0085] The control device 100 can control an amount of liquid refrigerant stored in the condenser based on the liquid phase area ratio A calculated according to equation (1). L % and the shape, volume, or the like of the capacitor stored in advance in the mass storage device 102. For details on the liquid phase area ratio A L % reference is made to Japanese Patent No. 5063346.

[0086] The control device 100 can thus calculate the total amount of liquid refrigerant remaining in the refrigerant circuit 200 by calculating the amount of liquid refrigerant stored in the accumulator 70, calculating the amount of liquid refrigerant stored in the condenser, and adding the amount of liquid refrigerant stored in the accumulator 70 to the amount of liquid refrigerant stored in the condenser. In the evaporator, the refrigerant is gasified, and the gasified refrigerant flows into the accumulator 70, so that no liquid refrigerant remains.

[0087] The control device 100 transmits to the user device 500 liquid refrigerant amount data indicating the amount of liquid refrigerant stored in the receiver 70, the amount of liquid refrigerant stored in the condenser, or the calculated total amount of liquid refrigerant remaining in the refrigerant cycle 200. The user device 500 notifies a user, such as an operator, on a display or the like of the amount of liquid refrigerant stored in the receiver 70, the amount of liquid refrigerant stored in the condenser, and the total amount of liquid refrigerant remaining in the refrigerant cycle 200, which is calculated based on the liquid refrigerant amount data obtained from the control device 100.

[0088] The air conditioning system 1 can thus calculate the amount of liquid refrigerant stored in the receiver 70 based on the SH difference between the ACC inlet SH and the ACC outlet SH, and notify the operator of the calculated amount of liquid refrigerant so that the operator can check the amount of liquid refrigerant stored in the receiver 70 at a lower cost.

[0089] A concrete flow of the refrigerant amount detection process performed by the air conditioner 1 will be described with reference to Fig. 6 described. Fig. Fig. 6 is a flowchart illustrating the refrigerant amount detection process performed by the air conditioner 1 according to the first embodiment. The control device 100 performs the refrigerant amount detection process in the manner shown in Fig. 6 by, for example, executing a program stored in mass storage 102. The "S" in the figure is used as an abbreviation for "STEP."

[0090] As in Fig. As shown in Figure 6, the controller 100 operates various components of the refrigerant circuit 200 of the air conditioner 1 (S1) and performs processing related to the first operation mode. Specifically, the controller 100 controls the compressor 30 to change the compressor frequency (S2). The controller 100 controls the outdoor fan 51 to change the outdoor fan speed (S3). The controller 100 controls the indoor expansion valve 65 to change the LEV opening (S4).

[0091] The controller 100 determines whether the condenser outlet SC has reached a prescribed value (S5). If the condenser outlet SC has not reached the prescribed value (NO in S5), the controller 100 controls the indoor expansion valve 65 again to change the LEV opening (S4).

[0092] If the condenser outlet SC has reached the prescribed value (YES in S5), the controller 100 determines whether the evaporation temperature has reached a prescribed value (S6). If the evaporation temperature has not reached the prescribed value (NO in S6), the controller 100 controls the outdoor fan 51 again to change the outdoor fan speed (S3).

[0093] If the evaporation temperature has reached the prescribed value (YES in S6), the controller 100 determines whether the condensation temperature has reached a prescribed value (S7). If the condensation temperature has not reached the prescribed value (NO in S7), the controller 100 controls the compressor 30 again to change the compressor frequency (S2).

[0094] The control device 100 can control the refrigeration cycle by the processing relating to the first operation mode in S2 to S7 in the Fig. 4 shown stable state.

[0095] When the condensation temperature has reached the prescribed value (YES in S7), the controller 100 calculates the liquid phase area ratio A L % (S8). The control device 100 can thus calculate the amount of liquid refrigerant stored in the condenser.

[0096] The control device 100 then performs processing related to the second operating mode. Specifically, the control device 100 begins counting a predetermined time period for performing the processing related to the second operating mode (S9).

[0097] The controller 100 controls the indoor expansion valve 65 to change the LEV opening so that the LEV opening in the second operation mode is set to be smaller than the LEV opening in the first operation mode (S10).

[0098] The controller 100 controls the compressor 30 to change the compressor frequency so that the compressor frequency in the second operating mode is set to be lower than the compressor frequency in the first operating mode (S11). For example, the controller 100 controls the compressor 30 to minimize the compressor frequency.

[0099] The controller 100 sets the outdoor fan speed to a prescribed value to set the air flow rate of the outdoor fan 51 in the second operation mode equal to the air flow rate of the outdoor fan 51 in the first operation mode (S12).

[0100] The control device 100 calculates the SH difference, while the SH difference as in Fig. 4, by processing related to the second operation mode described above in S10 to S12 (S14). The control device 100 calculates the amount of liquid refrigerant stored in the accumulator 70 based on the calculated SH difference (S15). Specifically, the control device 100 has data on the change in the ACC liquid level with respect to the SH difference, as shown in Fig. 5, which are stored in advance in the mass storage 102, and calculates the ACC liquid level based on the data and the calculated SH difference. Furthermore, the controller 100 calculates the amount of liquid refrigerant stored in the accumulator 70 based on the calculated ACC liquid level and the shape, volume, or the like of the container 71 stored in advance in the mass storage 102.

[0101] The control device 100 transmits the liquid refrigerant quantity data, which indicates the quantity of liquid refrigerant stored in the receiver 70, the quantity of liquid refrigerant stored in the condenser, or the total quantity of liquid refrigerant remaining in the refrigerant circuit 200, to the user device 500 (S16). The operator can thus check the quantity of liquid refrigerant stored in the receiver 70 using the user device 500.

[0102] The controller 100 determines in S9 whether a prescribed period of time has elapsed since the start of counting (S17). If the prescribed period of time has not elapsed since the start of counting in S9 (NO in S17), the process returns to S14, and the controller 100 recalculates the SH difference (S14). However, if the prescribed period of time has elapsed since the start of counting in S9 (YES in S17), the controller 100 terminates the current process. The controller 100 can calculate the liquid phase area ratio A L % for example before S14 or after S15 without having to calculate the liquid phase area ratio A L % in S8 to be limited.

[0103] As stated above, since the air conditioning system 1 according to the first embodiment can calculate the amount of liquid refrigerant stored in the receiver 70 based on the SH difference between the ACC inlet SH and the ACC outlet SH, and notify the operator of the calculated amount of liquid refrigerant, the operator can check the amount of liquid refrigerant stored in the receiver 70 in a more cost-effective manner. Second embodiment.

[0104] An air conditioning system 1 according to a second embodiment will be described with reference to Fig. 7. The features of the air conditioner 1 according to the second embodiment that are the same as those of the air conditioner 1 according to the first embodiment are denoted by the same reference numerals. A feature that differs from the air conditioner 1 according to the first embodiment is denoted by a different reference numeral, and details thereof will be described below.

[0105] Fig. 7 is a diagram showing a configuration of the air conditioner 1 and the air conditioning system 1000 according to the second embodiment. As shown in Fig. 7, the air conditioner 1 according to the second embodiment further includes an outdoor expansion valve 55.

[0106] The outdoor expansion valve 55 is, for example, an electronic expansion valve whose opening is adjusted under the control of the control device 100. The outdoor expansion valve 55 reduces the pressure of the incoming refrigerant and allows the refrigerant obtained by the pressure reduction to flow out. The control device 100 can adjust the amount of pressure reduction of the refrigerant by adjusting the opening of the outdoor expansion valve 55. One end of the outdoor expansion valve 55 is connected to the indoor unit 400 via the conduit 16 and the extension conduit 22. The other end of the outdoor expansion valve 55 is connected to the outdoor heat exchanger 50 via a conduit 20.

[0107] In the air conditioning system 1 according to the second embodiment configured as described above, after the refrigeration cycle is set to the steady state in the first operation mode, the controller 100 controls the outdoor expansion valve 55 instead of the indoor expansion valve 65 to set the opening of the outdoor expansion valve 55 in the second operation mode to be smaller than the opening of the outdoor expansion valve 55 in the first operation mode. Thus, the controller 100 can also reduce the amount of refrigerant flowing to the evaporator by reducing the opening of the outdoor expansion valve 55, and consequently, set the ACC inlet SH to be higher than the ACC outlet SH, and can generate the SH difference.

[0108] The control device 100 should reduce the opening of at least one of the indoor expansion valve 65 and the outdoor expansion valve 55 only in the second operating mode. In other words, in the second operating mode, the control device 100 can reduce only the opening of the indoor expansion valve 65, only the opening of the outdoor expansion valve 55, or the opening of both the indoor expansion valve 65 and the outdoor expansion valve 55. Third embodiment.

[0109] An air conditioning system 1 according to a third embodiment will be described. In the air conditioning system 1 according to the first embodiment, in the second operating mode, the controller 100 sets the rotational speed of the outdoor fan to the prescribed value to set the air flow rate of the outdoor fan 51 in the second operating mode equal to the air flow rate of the outdoor fan 51 in the first operating mode. In the air conditioning system 1 according to the third embodiment, in the second operating mode, the controller 100 may increase the rotational speed of the outdoor fan to the prescribed value to set the air flow rate of the outdoor fan 51 in the second operating mode to be greater than the air flow rate of the outdoor fan 51 in the first operating mode.

[0110] Therefore, when the controller 100 sets the air flow rate of the outdoor fan 51 in the second operation mode to be larger than the air flow rate of the outdoor fan 51 in the first operation mode, gasification of the refrigerant flowing to the evaporator can be further accelerated, and consequently, the ACC inlet SH can be set to be higher than the ACC outlet SH, and the SH difference can be more easily generated. Fourth embodiment.

[0111] An air conditioning system 1 according to a fourth embodiment will be described. In the air conditioning system 1 according to the first embodiment, the controller 100 is configured to detect the ACC liquid level based on the SH difference generated in the second operation mode. The ACC inlet SH can be calculated by subtracting the evaporating temperature from the refrigerant temperature at the ACC inlet, and the ACC outlet SH can be calculated by subtracting the evaporating temperature from the refrigerant temperature at the ACC outlet. Since the same evaporating temperature is used to calculate the ACC inlet SH and the ACC outlet SH, the SH difference between the ACC inlet SH and the ACC outlet SH is proportional to a difference between the ACC inlet refrigerant temperature T1 and the ACC outlet refrigerant temperature T2.

[0112] In the air conditioning system 1 according to the fourth embodiment, the control device 100 can detect the ACC liquid level based on the difference between the refrigerant temperature T1 at the ACC inlet and the refrigerant temperature T2 at the ACC outlet. Specifically, in the Fig. 5, the SH difference shown on the abscissa is replaced by the difference between the refrigerant temperature T1 at the ACC inlet and the refrigerant temperature T2 at the ACC outlet, so that the controller 100 can obtain data on the change in the ACC liquid level with respect to the difference between the refrigerant temperature T1 at the ACC inlet and the refrigerant temperature T2 at the ACC outlet. The controller 100 can use this data to detect the ACC liquid level based on the difference between the refrigerant temperature T1 at the ACC inlet and the refrigerant temperature T2 at the ACC outlet.

[0113] The refrigerant amount detection process performed by the air conditioner 1 according to each of the first to fourth embodiments described above can also be performed in the cooling operation mode without being limited to the heating operation mode. In the air conditioner 1 according to each of the first to fourth embodiments described above, the temperature sensor 92 provided between the outlet side of the receiver 70 and the inlet 31 of the compressor 30 is illustrated as a "second temperature sensor" for measuring the temperature of the refrigerant flowing out of the receiver 70. However, a temperature sensor installed elsewhere may be used as the "second temperature sensor." For example, the refrigerant temperature T2 of the refrigerant flowing out of the receiver 70 is precisely matched to the temperature T3 of the refrigerant discharged from the compressor 30.Therefore, the temperature sensor 93 can be used as a "second temperature sensor," and the refrigerant temperature T3 can be used as the "second measurement result." In this case, the temperature sensor 92 need not be provided. In an example where the compressor 30 is configured such that the compression mechanism is located in an airtight container filled with suction or discharged refrigerant, a temperature sensor (not shown) for detecting a surface temperature of the airtight container can be used as the "second temperature sensor," and the surface temperature of the airtight container can be used as the "second measurement result." Since the airtight container of the compressor 30 is filled with the refrigerant flowing out of the receiver 70, the surface temperature of the airtight container of the compressor 30 corresponds to the temperature of the refrigerant flowing out of the receiver 70. [Summary]

[0114] The air conditioning system 1 in the present disclosure includes the refrigerant circuit 200 comprising the compressor 30, the condenser (e.g., indoor heat exchanger 60), at least one expansion valve (e.g., indoor expansion valve 65, outdoor expansion valve 55), and the evaporator (e.g., outdoor heat exchanger 50), a refrigerant circuit 200 configured to circulate refrigerant, a controller 100 for controlling the refrigerant circuit 200, a receiver 70 in which liquid refrigerant is stored, the receiver 70 being configured to separate refrigerant flowing through the refrigerant circuit 200 into liquid refrigerant and gaseous refrigerant, a temperature sensor 91 for measuring a temperature T1 of refrigerant flowing into the receiver 70, and a temperature sensor 92 for measuring a temperature T2 of refrigerant flowing out of the receiver 70.The accumulator 70 is arranged between the compressor 30 and the evaporator. The control device 100 calculates the amount of liquid refrigerant stored in the accumulator 70 based on the refrigerant temperature T1, which is a result of the measurement by the temperature sensor 91, and the refrigerant temperature T2, which is a result of the measurement by the temperature sensor 92.

[0115] With such a configuration, the air conditioner 1 can calculate the amount of liquid refrigerant stored in the receiver 70 based on the temperature T1 of the refrigerant flowing into the receiver 70 and the temperature T2 of the refrigerant flowing out of the receiver 70, so that the operator can check the amount of liquid refrigerant stored in the receiver 70 more cost-effectively.

[0116] The control device 100 calculates the amount of liquid refrigerant stored in the collector 70 based on the difference between the temperature T1 of the refrigerant flowing into the collector 70 and the temperature T2 of the refrigerant flowing out of the collector 70.

[0117] According to the above configuration, the air conditioner 1 can calculate the amount of liquid refrigerant stored in the receiver 70 based on the difference between the temperature T1 of the refrigerant flowing into the receiver 70 and the temperature T2 of the refrigerant flowing out of the receiver 70, so that the operator can check the amount of liquid refrigerant stored in the receiver 70 more cost-effectively.

[0118] The air conditioning system 1 further includes the pressure sensor 81 for measuring the pressure P1 of refrigerant flowing into the accumulator 70. The controller 100 calculates the superheat degree (ACC inlet SH) of the refrigerant flowing into the accumulator 70 based on the refrigerant pressure P1 measured by the pressure sensor 81 and the temperature T1 of the refrigerant flowing into the accumulator 70, calculates the superheat degree (ACC outlet SH) of the refrigerant flowing out of the accumulator 70 based on the refrigerant pressure P1 measured by the pressure sensor 81 and the temperature T2 of the refrigerant flowing out of the accumulator 70, and calculates the amount of liquid refrigerant stored in the accumulator 70 based on the SH difference between the ACC inlet SH and the ACC outlet SH.

[0119] According to the above configuration, the air conditioner 1 can calculate the amount of liquid refrigerant stored in the receiver 70 based on the SH difference between the ACC inlet SH and the ACC outlet SH, so that the operator can check the amount of liquid refrigerant stored in the receiver 70 more cost-effectively.

[0120] The control device 100 controls the refrigerant cycle 200 in a first operation mode in which the SH difference between the ACC inlet SH and the ACC outlet SH is set to be smaller than a prescribed value, and thereafter controls the refrigerant cycle 200 in a second operation mode in which the SH difference between the ACC inlet SH and the ACC outlet SH is set to be equal to or greater than the prescribed value, and calculates the amount of liquid refrigerant stored in the accumulator 70 in the second operation mode.

[0121] According to the above configuration, the air conditioner 1 controls the refrigerant cycle 200 in the second operation mode to place the refrigerant cycle in the transition state, thereby generating the SH difference between the ACC inlet SH and the ACC outlet SH. The air conditioner 1 can thus detect the amount of liquid refrigerant stored in the accumulator 70 based on the SH difference generated in the second operation mode.

[0122] The control device 100 sets the opening of at least one expansion valve (for example, indoor expansion valve 65, outdoor expansion valve 55) in the second operating mode to be smaller than the opening of the at least one expansion valve (for example, indoor expansion valve 65, outdoor expansion valve 55) in the first operating mode.

[0123] According to the above configuration, the air conditioner 1 can reduce the amount of refrigerant flowing to the evaporator by reducing the opening of at least one expansion valve (for example, indoor expansion valve 65, outdoor expansion valve 55), and thus can set the ACC inlet SH to be higher than the ACC outlet SH, and can generate the SH difference.

[0124] The at least one expansion valve is an indoor expansion valve 65 arranged in the indoor unit 400 or an outdoor expansion valve 55 arranged in the outdoor unit 300.

[0125] According to the above configuration, the air conditioner 1 can reduce the amount of refrigerant flowing to the evaporator by reducing the opening of at least one of the indoor expansion valve 65 and the outdoor expansion valve 55, and thus can set the ACC inlet SH to be higher than the ACC outlet SH, and can generate the SH difference.

[0126] The air conditioning system 1 further includes a fan (e.g., outdoor fan 51) for supplying air to the evaporator. The control device 100 sets an air flow rate of the fan in the second operating mode to be equal to the air flow rate of the fan in the first operating mode.

[0127] According to the above configuration, the air conditioner 1 can reduce the amount of refrigerant flowing to the evaporator by reducing the opening of at least one expansion valve (for example, indoor expansion valve 65, outdoor expansion valve 55) and maintaining the air flow rate of the fan (for example, outdoor fan 51) to send air to the evaporator, and thus can set the ACC inlet SH to be higher than the ACC outlet SH, and can generate the SH difference.

[0128] The air conditioning system 1 further includes a fan (e.g., outdoor fan 51) for supplying air to the evaporator. The control device 100 sets the air flow rate of the fan in the second operating mode to be greater than the air flow rate of the fan in the first operating mode.

[0129] According to the above configuration, the air conditioner 1 can reduce the amount of refrigerant flowing to the evaporator by reducing the opening of at least one expansion valve (for example, indoor expansion valve 65, outdoor expansion valve 55) and increasing the air flow rate of the fan (for example, outdoor fan 51) to send air to the evaporator, and thus can set the ACC inlet SH to be higher than the ACC outlet SH, and can generate the SH difference.

[0130] The controller 100 sets the frequency of the compressor 30 in the second operating mode to be lower than the frequency of the compressor 30 in the first operating mode.

[0131] According to the above configuration, the air conditioner 1 can accelerate the gasification of refrigerant in the evaporator by setting the frequency of the compressor 30 in the second operation mode to be lower than the frequency of the compressor 30 in the first operation mode, and can thus set the ACC inlet SH to be higher than the ACC outlet SH, and can generate the SH difference. In addition, the air conditioner 1, as shown in Fig. 5, ensure a wider range within which a change in the ACC liquid level with respect to the SH difference is detected when the frequency of the compressor 30 is lowered in the second operating mode.

[0132] The air conditioning system 1000 in the present disclosure includes the air conditioning system 1 described above and the user device 500 for issuing a notification of the amount of liquid refrigerant stored in the accumulator 70, the amount being calculated by the air conditioning system 1.

[0133] According to the above configuration, the air conditioning system 1000 can notify the operator of the amount of liquid refrigerant stored in the accumulator 70 and calculated by the air conditioner 1 by means of the user device 500, thereby improving the usability of the operator.

[0134] It is to be understood that the embodiments disclosed herein are in all respects illustrative and not restrictive. The scope of the present disclosure is defined by the terms of the claims rather than by the above description of the embodiments, and is intended to include all changes within the scope and meaning that come within the terms of the claims. LIST OF REFERENCE SYMBOLS

[0135] 1 Air conditioning system; 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 Pipe; 21, 22 Extension pipe; 30 Compressor; 31 Inlet; 32 Outlet; 40 Four-way valve; 41, 42, 43, 44 Connection opening; 50 Outdoor heat exchanger; 51 Outdoor fan; 55 Outdoor expansion valve; 60 Indoor heat exchanger; 61 Indoor fan; 65 Indoor expansion valve; 70 Receiver; 71 Tank; 72 Inlet pipe; 73 Outlet pipe; 73a Gas inlet; 73b Liquid inlet; 81, 82 Pressure sensor; 91, 92, 93, 94, 95 Temperature sensor; 100 Control device; 101 Control unit; 102 Mass storage device; 200 Refrigerant circuit; 300 Outdoor unit; 400 Indoor unit; 500 User equipment; 1000 Air conditioning system. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2019 / 065242 [0003, 0004, 0005] JP 5063346

[0085]

Claims

[1] Air conditioning system, comprising: a refrigerant circuit comprising a compressor, a condenser, at least one expansion valve and an evaporator, wherein the refrigerant circuit is configured to circulate refrigerant; a control device configured to control the refrigerant circuit; a collector in which liquid refrigerant is stored, the collector being configured to separate refrigerant flowing through the refrigerant circuit into liquid refrigerant and gaseous refrigerant; a first temperature sensor configured to measure a temperature of the refrigerant flowing into the collector; and a second temperature sensor configured to measure a temperature of the refrigerant flowing out of the collector, wherein the collector is located between the compressor and the evaporator, and the control device calculates an amount of the liquid refrigerant stored in the accumulator based on a first measurement result of the first temperature sensor and a second measurement result of the second temperature sensor. [2] The air conditioner according to claim 1, wherein the control means calculates an amount of the liquid refrigerant stored in the accumulator based on a difference between the first measurement result and the second measurement result. [3] The air conditioning system according to claim 2, further comprising a pressure sensor configured to measure a pressure of the refrigerant flowing into the collector, wherein the control device calculates a first degree of superheat of the refrigerant flowing into the receiver based on a measurement result of the pressure sensor and the first measurement result, calculates a second superheat degree of the refrigerant flowing out of the receiver based on the measurement result of the pressure sensor and the second measurement result, and the amount of liquid refrigerant stored in the receiver is calculated based on a difference between the first superheat level and the second superheat level. [4] Air conditioning system according to claim 3, wherein the control device controls the refrigerant circuit in a first operating mode in which the difference between the first superheat degree and the second superheat degree is set to be smaller than a prescribed value, and thereafter the control device controls the refrigerant circuit in a second operating mode in which the difference between the first superheat degree and the second superheat degree is set to be equal to or greater than the prescribed value, and the control device calculates the amount of liquid refrigerant stored in the receiver in the second operating mode. [5] The air conditioning system according to claim 4, wherein the control device sets an opening of the at least one expansion valve in the second operating mode to be smaller than an opening of the at least one expansion valve in the first operating mode. [6] The air conditioning system according to claim 5, wherein the at least one expansion valve is an indoor expansion valve arranged in an indoor unit or an outdoor expansion valve arranged in an outdoor unit. [7] The air conditioning system according to claim 5, further comprising a fan for sending air to the evaporator, wherein the control device sets an air flow rate of the fan in the second operating mode to be equal to an air flow rate of the fan in the first operating mode. [8] The air conditioning system according to claim 5, further comprising a fan for sending air to the evaporator, wherein the control device sets an air flow rate of the fan in the second operating mode to be greater than an air flow rate of the fan in the first operating mode. [9] The air conditioning system according to any one of claims 5 to 8, wherein the control means sets a frequency of the compressor in the second operation mode to be lower than a frequency of the compressor in the first operation mode. [10] Air conditioning system comprising: the air conditioning system according to one of claims 1 to 9; and a user device for issuing a notification of the amount of liquid refrigerant stored in the receiver, the amount being calculated by the air conditioning system.

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