WO2023228353A1

WO2023228353A1 - Air conditioning device

Info

Publication number: WO2023228353A1
Application number: PCT/JP2022/021540
Authority: WO
Inventors: 智典小島; 達也 ▲雑▼賀
Original assignee: 三菱電機株式会社
Priority date: 2022-05-26
Filing date: 2022-05-26
Publication date: 2023-11-30

Abstract

This air conditioning device comprises: a refrigerant circuit in which a refrigerant circulates, and a control device that controls the refrigerant circuit. The refrigerant circuit includes: a main circuit in which a compressor, a first open/close valve, a reheater, a first expansion valve, and an evaporator are sequentially linked by main piping; a cooling circuit in which a second open/close valve, a condenser, and a second expansion valve are sequentially linked by cooling piping connecting an area spanning from between the compressor and the first open/close circuit to between the first expansion valve and the evaporator; and a bypass circuit including bypass piping bypass piping connecting an area spanning from a discharge side of the compressor to between the reheater and the first expansion valve, and a third open/close valve that opens and closes the bypass piping. The reheater and the evaporator are disposed in an air conditioning space, and the condenser is disposed outside of the air conditioning space. The control device, before switching operation to a cooling operation for cooling the air in the air conditioning space or to a dehumidifying operation for dehumidifying the air in the air conditioning space, performs operation switching control in which the first open/close valve and the second open/close valve are set to an open state, the third open/close valve is set to a closed state, and the first expansion valve is used to control overheating of an intake side of the compressor and the second expansion valve is used to control overcooling of the condenser.

Description

air conditioner

The present disclosure relates to an air conditioner having a reheater and an evaporator provided indoors and a condenser provided outdoors.

BACKGROUND ART Conventionally, there has been known an air conditioner having a reheater and an evaporator provided indoors and a condenser provided outdoors (see, for example, Patent Document 1). The air conditioner of Patent Document 1 controls the dehumidifying ability of the evaporator by adjusting the amount of refrigerant flowing into the reheater and the amount of refrigerant flowing into the condenser.

Japanese Patent Application Publication No. 2011-133171

However, in the air conditioner of Patent Document 1, the refrigerant distributed in each heat exchanger may be uneven due to the difference in outside air temperature, and liquid back may occur when performing cooling operation or dehumidification operation. Also, there is a possibility of overheating operation. When liquid back occurs, there is a problem that liquid compression occurs in the compressor, which may cause the compressor to malfunction. In addition, when overheating occurs, the amount of refrigerant circulating between the compressor, reheater, expansion valve, and evaporator is insufficient, resulting in a decrease in capacity and an increase in discharge temperature, making operation more efficient. The problem was that it could not be done.

The present disclosure has been made to solve the above-mentioned problems, and provides an air conditioner that can suppress the occurrence of imbalance in the refrigerant distributed in each heat exchanger before performing a cooling operation or a dehumidification operation. The purpose is to provide equipment.

The air conditioner according to the present disclosure includes a main circuit in which a compressor, a first on-off valve, a reheater, a first expansion valve, and an evaporator are sequentially connected through main piping, and the compressor and the first on-off valve. a cooling circuit in which a second on-off valve, a condenser, and a second expansion valve are sequentially connected by a cooling pipe connecting between the first expansion valve and the evaporator; and a discharge side of the compressor. a refrigerant circuit in which a refrigerant circulates, the refrigerant circuit comprising: a bypass pipe connecting the reheater to the first expansion valve; and a third on-off valve that opens and closes the bypass pipe. the reheater and the evaporator are arranged in an air-conditioned space, the condenser is arranged outside the air-conditioned space, and the control equipment controls the operation of the air-conditioned space. Before switching to a cooling operation that cools the air or a dehumidification operation that dehumidifies the air in the air-conditioned space, the first on-off valve and the second on-off valve are opened, and the third on-off valve is closed, The first expansion valve is used to control the degree of superheating on the suction side of the compressor, and the second expansion valve is used to control the degree of supercooling of the condenser. be.

According to the air conditioner according to the present disclosure, the control device opens the first on-off valve and the second on-off valve and closes the third on-off valve before switching the operation to the cooling operation or the dehumidification operation. The first expansion valve is used to control the degree of superheating on the suction side of the compressor, and the second expansion valve is used to control the degree of subcooling of the condenser. By implementing this operation switching control, the amount of refrigerant is adjusted to an appropriate value, so it is possible to prevent uneven distribution of refrigerant in each heat exchanger before performing cooling operation or dehumidification operation. .

1 is an overall configuration diagram of an air conditioner according to Embodiment 1. FIG. 2 is a block diagram schematically showing the functional configuration of the control device shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing the state of a refrigerant circuit during dehumidification operation of the air conditioner shown in FIG. 1. FIG. 2 is an explanatory diagram showing the state of a refrigerant circuit during intermediate operation of the air conditioner shown in FIG. 1. FIG. 2 is an explanatory diagram showing the state of a refrigerant circuit during cooling operation of the air conditioner shown in FIG. 1. FIG. 2 is an explanatory diagram showing the state of a refrigerant circuit during defrosting operation of the air conditioner shown in FIG. 1. FIG. 2 is a flowchart illustrating operation switching control of the air conditioner shown in FIG. 1. FIG. 2 is a flowchart illustrating refrigerant distribution control during cooling operation of the air conditioner shown in FIG. 1. FIG. 2 is a flowchart illustrating refrigerant distribution control during dehumidification operation of the air conditioner shown in FIG. 1. FIG. FIG. 3 is a diagram showing an example of the operation contents of each on-off valve and each expansion valve when a refrigerant leaks in the air conditioner according to the first embodiment. FIG. 2 is an overall configuration diagram of an air conditioner according to a second embodiment.

Hereinafter, embodiments of the present disclosure will be described based on the drawings. Note that the present disclosure is not limited to the embodiments described below. Further, in the following drawings, the size relationship of each component may differ from the actual one.

Embodiment 1.
FIG. 1 is an overall configuration diagram of an air conditioner 100 according to the first embodiment. Air conditioner 100 according to Embodiment 1 adjusts the temperature and humidity of air in an air-conditioned space such as a room. As shown in FIG. 1, the air conditioner 100 includes an indoor unit 70 installed within the air-conditioned space and an outdoor unit 80 installed outside the air-conditioned space. The indoor unit 70 and the outdoor unit 80 are connected by a refrigerant pipe 20. Note that hereinafter, the inside of the air-conditioned space will also be referred to as indoors, and the outside of the air-conditioned space will also be referred to as outdoors.

The indoor unit 70 is, for example, a floor-standing dehumidifier placed on the floor of an air-conditioned space, a ceiling-mounted dehumidifier or a ceiling-mounted dehumidifier installed on the ceiling, or the like. The indoor unit 70 includes a compressor 1, a first on-off valve 2, a reheater 3, a first expansion valve 4, an indoor heat exchanger 5, a second on-off valve 6, a second expansion valve 9, and a third on-off valve. 10 are accommodated. The outdoor unit 80 is installed outdoors or in a machine room. The outdoor unit 80 houses an outdoor heat exchanger 7 and a liquid reservoir 8 . That is, the air conditioner 100 includes a compressor 1, a first on-off valve 2, a reheater 3, a first expansion valve 4, an indoor heat exchanger 5, a second on-off valve 6, an outdoor heat exchanger 7, and a liquid reservoir 8. , the second expansion valve 9, and the third on-off valve 10 are connected by a refrigerant pipe 20, and has a refrigerant circuit 30 in which refrigerant circulates. Note that, hereinafter, the indoor heat exchanger 5 will also be referred to as an evaporator, and the outdoor heat exchanger 7 will also be referred to as a condenser.

As the refrigerant to be circulated through the refrigerant circuit 30, a single mixed refrigerant, a pseudo-single refrigerant mixture, a non-azeotropic mixed refrigerant, or the like can be used. As the non-azeotropic mixed refrigerant, for example, a mixed refrigerant of R32, R125, R134a, r1234yf, and CO ₂ can be used. This non-azeotropic mixed refrigerant has a composition of R32 of 49 wt% to 55 wt%, a composition of R125 of 16 wt% to 22 wt%, a composition of R134a of 7 wt% to 13 wt%, and a composition of R1234yf of 6 wt%. ~12 wt%, and the CO ₂ composition is 7 wt% to 13 wt%, with a total composition ratio of 100 wt%. Further, as the non-azeotropic mixed refrigerant, R448A, R449A, or R407F, which are non-azeotropic mixed refrigerants having compositions other than those mentioned above, may be employed.

The refrigerant pipe 20 is composed of a main pipe 21, a cooling pipe 22, and a bypass pipe 23. The main pipe 21 is a pipe that sequentially connects the compressor 1, the first on-off valve 2, the reheater 3, the first expansion valve 4, and the indoor heat exchanger 5 in an annular manner. That is, the refrigerant circuit 30 includes a main circuit 31 formed by connecting the compressor 1 , the first on-off valve 2 , the reheater 3 , the first expansion valve 4 , and the indoor heat exchanger 5 via the main pipe 21 . .

The cooling pipe 22 is a pipe that connects between the compressor 1 and the reheater 3 and between the first expansion valve 4 and the indoor heat exchanger 5. More specifically, the cooling pipe 22 connects the main pipe 21 between the compressor 1 and the first on-off valve 2 and the main pipe 21 between the first expansion valve 4 and the indoor heat exchanger 5. , is a pipe connecting the second on-off valve 6, the outdoor heat exchanger 7, the liquid reservoir 8, and the second expansion valve 9. That is, the refrigerant circuit 30 includes a cooling circuit 32 that is an open circuit in which the second on-off valve 6 , the outdoor heat exchanger 7 , the liquid reservoir 8 , and the second expansion valve 9 are connected by the cooling pipe 22 . Here, the connection part between the main pipe 21 and the cooling pipe 22 between the compressor 1 and the first on-off valve 2 is referred to as a first connection part M. Moreover, the connection part between the main pipe 21 and the cooling pipe 22 between the first expansion valve 4 and the indoor heat exchanger 5 is referred to as a second connection part N.

The bypass pipe 23 is a pipe that connects the discharge side of the compressor 1 to between the reheater 3 and the first expansion valve 4. In the first embodiment, the discharge side of the compressor 1 is between the compressor 1 and the first connecting portion M. More specifically, the bypass pipe 23 is a pipe that connects the main pipe 21 between the compressor 1 and the first connection part M and the main pipe 21 between the reheater 3 and the first expansion valve 4. A third on-off valve 10 that opens and closes the bypass pipe 23 is provided. That is, the refrigerant circuit 30 includes a bypass circuit 33 that is an open circuit in which the third on-off valve 10 is provided in the bypass pipe 23. Here, as shown in FIG. 1, the reheater 3 and the first expansion valve 4, and the outdoor heat exchanger 7 and the second expansion valve 9 are connected in parallel.

The compressor 1 takes in refrigerant, compresses it, turns it into a high-temperature, high-pressure gas state, and discharges it. The compressor 1 is a compressor whose rotational speed is controlled by, for example, an inverter circuit, and the amount of refrigerant discharged can be adjusted. However, the compressor 1 may be a constant speed compressor that operates at a constant rotation speed.

The reheater 3, the indoor heat exchanger 5, and the outdoor heat exchanger 7 are, for example, fin-and-tube heat exchangers formed by pipes through which a refrigerant flows and fins attached to the pipes. The reheater 3 condenses the refrigerant by exchanging heat between the refrigerant compressed by the compressor 1 and air. In the air conditioner 100, the indoor heat exchanger 5 and the reheater 3 are provided on a common wind path. On the same wind path, an indoor heat exchanger 5 with a dehumidifying function is placed on the windward side, and a reheater 3 with a heating function is placed on the leeward side of the indoor heat exchanger 5, and the temperature of the air blown from the indoor unit 70 into the air-conditioned space is adjusted. An operation is performed with a certain blowout temperature adjusted. The indoor heat exchanger 5 is an air heat exchanger that functions as an evaporator (cooler) that evaporates refrigerant. That is, the indoor heat exchanger 5 evaporates the refrigerant by exchanging heat between the refrigerant expanded by at least one of the first expansion valve 4 and the second expansion valve 9 and air. The outdoor heat exchanger 7 is an air heat exchanger that functions as a condenser that condenses refrigerant. That is, the outdoor heat exchanger 7 condenses the refrigerant by exchanging heat between the refrigerant compressed by the compressor 1 and air.

The first expansion valve 4 is, for example, an electronic expansion valve, and is arranged downstream of the reheater 3. The first expansion valve 4 expands the refrigerant condensed in the reheater 3. The second expansion valve 9 is, for example, an electronic expansion valve, and is arranged downstream of the outdoor heat exchanger 7. The second expansion valve 9 expands the refrigerant condensed in the outdoor heat exchanger 7.

The first on-off valve 2, the second on-off valve 6, and the third on-off valve 10 are, for example, electromagnetic valves that have an open state and a closed state, and allow refrigerant to pass through in the open state. When the first on-off valve 2 is in the closed state, it cuts off the refrigerant that is about to flow into the reheater 3 via the first connection part M. When the second on-off valve 6 is in the closed state, it cuts off the refrigerant that is about to flow into the outdoor heat exchanger 7 via the first connection part M. The third on-off valve 10 cuts off refrigerant flowing into the bypass pipe 23 when in the closed state. The liquid reservoir 8 is a member that stores surplus refrigerant.

Further, the indoor unit 70 is provided with an indoor blower 11 that sends air to the indoor heat exchanger 5 and the reheater 3. The outdoor unit 80 is provided with an outdoor blower 12 that is attached to the outdoor heat exchanger 7 and sends air to the outdoor heat exchanger 7 . In the first embodiment, the indoor blower 11 and the outdoor blower 12 are blowers whose rotational speed is controlled by, for example, an inverter circuit, and whose air flow rate can be adjusted.

Furthermore, the indoor unit 70 is provided with an indoor refrigerant leak sensor 41, a control device 50, pressure sensors 61 to 63, refrigerant temperature sensors 65 to 68, and an air temperature sensor 91. The outdoor unit 80 is provided with an outdoor refrigerant leak sensor 42, a pressure sensor 64, a refrigerant temperature sensor 69, and an air temperature sensor 92.

The pressure sensor 61 is provided on the suction side of the compressor 1 and measures low pressure, which is the pressure of the refrigerant sucked by the compressor 1. The pressure sensor 62 is provided on the discharge side of the compressor 1 and measures high pressure, which is the pressure of the refrigerant discharged from the compressor 1. The pressure sensor 63 is provided on the outlet side of the reheater 3, that is, at or near the outlet of the reheater 3, and measures the reheater outlet pressure, which is the pressure of the refrigerant flowing out from the reheater 3. The pressure sensor 64 is provided on the outlet side of the outdoor heat exchanger 7, that is, at or near the outlet of the outdoor heat exchanger 7, and measures the condenser outlet pressure, which is the pressure of the refrigerant flowing out from the outdoor heat exchanger 7.

The refrigerant temperature sensors 65 to 69 are composed of, for example, thermistors. The refrigerant temperature sensor 65 is provided on the suction side of the compressor 1 and measures the suction temperature, which is the temperature of the refrigerant sucked into the compressor 1. The refrigerant temperature sensor 66 is provided on the discharge side of the compressor 1 and measures the discharge temperature, which is the temperature of the refrigerant discharged from the compressor 1. The refrigerant temperature sensor 67 is provided on the exit side of the reheater 3 and measures the reheater outlet temperature, which is the temperature of the refrigerant flowing out from the reheater 3. The refrigerant temperature sensor 68 is provided on the exit side of the indoor heat exchanger 5 and measures the evaporator exit temperature, which is the temperature of the refrigerant flowing out from the indoor heat exchanger 5. The refrigerant temperature sensor 69 is provided on the outlet side of the outdoor heat exchanger 7 and measures the condenser outlet temperature, which is the temperature of the refrigerant flowing out from the outdoor heat exchanger 7.

The

air temperature sensors

91 and 92 are composed of, for example, thermistors. The air temperature sensor 91 is provided at the suction port of the indoor unit 70, and measures the temperature of the air-conditioned space as the indoor temperature. The air temperature sensor 92 is provided in the outdoor unit 80 and measures the temperature outdoors or in a machine room as outside air temperature.

The indoor refrigerant leak sensor 41 is provided within the air-conditioned space and detects refrigerant leakage. The outdoor refrigerant leak sensor 42 is provided outside the air-conditioned space and detects refrigerant leakage. When the indoor refrigerant leak sensor 41 and the outdoor refrigerant leak sensor 42 detect refrigerant leak, they output a leak signal indicating the occurrence of refrigerant leak to the control device 50. Each pressure sensor outputs measured pressure data to the control device 50. Each temperature sensor outputs measured temperature data to the control device 50. That is, each refrigerant leak sensor, each pressure sensor, and each temperature sensor are electrically or optically connected to the control device 50.

Furthermore, the indoor unit 70 is provided with an abnormality alarm 45 that includes at least one of a speaker and a light emitter. As the light emitter, an LED (light emitting diode) or the like can be used. The abnormality alarm 45 notifies the occurrence of an abnormality by outputting sound, voice, light, or the like in response to an instruction from the control device 50.

The control device 50 controls the refrigerant circuit 30. That is, the control device 50 acquires the output of each pressure sensor and each temperature sensor, and controls the compressor 1, the first on-off valve 2, the first expansion valve 4, the second on-off valve 6, the second expansion valve 9, and Controls various actuators such as the third on-off valve 10. Further, when an abnormality occurs, the control device 50 causes the abnormality alarm 45 to notify the occurrence of the abnormality. The control device 50 according to the first embodiment causes the abnormality alarm 45 to output sound, voice, light, etc. when each refrigerant leakage sensor detects an abnormality of refrigerant leakage.

The control device 50 is configured to include, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). RAM is a volatile storage medium that stores various data. The ROM is a non-volatile storage medium that stores operation programs for causing the control device 50 to execute operation control according to each operation mode, which will be described later. The control device 50 appropriately controls the compressor 1, the first on-off valve 2, the first expansion valve 4, the second on-off valve 6, the second expansion valve 9, the third on-off valve 10, etc. according to the operation program in the ROM. control and perform air conditioning according to each operation mode. That is, the control device 50 can be configured by a calculation device such as a CPU, and an operation program that cooperates with such a calculation device to realize the various functions described below.

Here, the flow of air in the indoor unit 70 will be schematically explained. When the indoor blower 11 operates, air is taken into the indoor unit 70. The air taken into the indoor unit 70 passes through the indoor heat exchanger 5, which functions as an evaporator, and its absolute humidity is reduced. That is, when the air containing moisture passes through the indoor heat exchanger 5, the moisture in the air condenses on the indoor heat exchanger 5, so that the absolute humidity of the air decreases. By passing through the indoor heat exchanger 5, the absolute humidity decreases, and the air whose temperature has decreased becomes cold air with high relative humidity. The air that has passed through the indoor heat exchanger 5 is reheated by passing through the reheater 3, and its relative humidity is reduced. Then, the air that has passed through the reheater 3 and has lowered relative humidity is blown into the room. As described above, the air taken into the indoor unit 70 is blown out into the room with its relative humidity reduced, so the relative humidity in the room is reduced. This is the air flow in the indoor unit 70 during dehumidification operation or intermediate operation, which will be described later.

FIG. 2 is a block diagram schematically showing the functional configuration of the control device 50 shown in FIG. 1. The control device 50 includes a calculation processing section 51 and a storage section 52. The calculation processing section 51 includes a setting processing section 51a, an operation control section 51b, a surplus refrigerant detection section 51c, and a leakage processing section 51d. The setting processing unit 51a receives an operation signal indicating the contents of the user's operation and settings from a remote controller (not shown) for operating the air conditioner 100 or the like. The setting processing unit 51a then sets the operating mode, target temperature, target humidity, etc. according to the operation signal.

The surplus refrigerant detection unit 51c detects the generation of surplus refrigerant using one of the following methods, and outputs a detection signal to the operation control unit 51b when detecting the generation of surplus refrigerant. For example, the surplus refrigerant detection unit 51c can be configured to determine the degree of subcooling and determine whether the determined degree of subcooling is greater than a degree of subcooling threshold. This determination utilizes the fact that the degree of supercooling increases when surplus refrigerant is generated. That is, the surplus refrigerant detection section 51c outputs a detection signal to the operation control section 51b when the obtained degree of subcooling is larger than the degree of subcooling threshold.

Additionally, the fact that the discharge temperature of the refrigerant becomes low when surplus refrigerant is generated may be used to detect surplus refrigerant. That is, the surplus refrigerant detection unit 51c may acquire the discharge temperature from the refrigerant temperature sensor 66, and determine whether the acquired discharge temperature is smaller than the discharge threshold. The surplus refrigerant detection section 51c may output a detection signal to the operation control section 51b when the discharge temperature is lower than the discharge threshold.

Furthermore, the increase in high pressure when surplus refrigerant is generated may be used to detect surplus refrigerant. That is, the surplus refrigerant detection unit 51c may acquire the high pressure from the pressure sensor 62 and determine whether the acquired high pressure is greater than the high pressure threshold. The surplus refrigerant detection section 51c may output a detection signal to the operation control section 51b when the high pressure is higher than the high pressure threshold.

In addition, the increase in low pressure when surplus refrigerant is generated may be used to detect surplus refrigerant. That is, the surplus refrigerant detection unit 51c may acquire the low pressure from the pressure sensor 61 and determine whether the acquired low pressure is greater than the low pressure threshold. The surplus refrigerant detection section 51c may output a detection signal to the operation control section 51b when the low pressure is greater than the low pressure threshold.

The leak processing unit 51d acquires leak signals from each of the indoor refrigerant leak sensor 41 and the outdoor refrigerant leak sensor 42. When a leak signal is output from the indoor refrigerant leak sensor 41, the leak processing section 51d outputs an indoor leak signal indicating the occurrence of indoor refrigerant leak to the operation control section 51b. When a leakage signal is output from the outdoor refrigerant leakage sensor 42, the leakage processing section 51d outputs an outdoor leakage signal indicating the occurrence of refrigerant leakage outdoors to the operation control section 51b.

Furthermore, when a leak signal is output from at least one of the indoor refrigerant leak sensor 41 and the outdoor refrigerant leak sensor 42, the leak processing unit 51d causes the abnormality alarm 45 to output sound, voice, light, etc. The leak processing unit 51d sends different sounds, sounds, lights, etc. to the abnormality alarm 45 depending on whether a leak signal is acquired from the indoor refrigerant leak sensor 41 or when a leak signal is acquired from the outdoor refrigerant leak sensor 42. You may also output it.

The operation control unit 51b periodically acquires measurement data from each pressure sensor and each temperature sensor. Then, the operation control section 51b controls the operation of each actuator of the air conditioner 100 using the acquired measurement data according to the settings made by the setting processing section 51a. The operation control unit 51b controls, for example, the rotation speeds of the compressor motor 1a of the compressor 1, the fan motor 11a of the indoor blower 11, and the fan motor 12a of the outdoor blower 12.

If the operation mode is set to the dehumidification operation mode by user operation or default setting, the operation control unit 51b causes the air conditioner 100 to perform a dehumidification operation to dehumidify the air in the air-conditioned space. When the operation mode is set to the intermediate operation mode, the operation control unit 51b causes the air conditioner 100 to perform an intermediate operation in which the air in the conditioned space is simultaneously dehumidified and cooled. When the operation mode is set to the cooling operation mode, the operation control unit 51b causes the air conditioner 100 to perform a cooling operation to cool the air in the air-conditioned space. When the operation mode is set to the defrosting operation mode, the operation control unit 51b causes the air conditioner 100 to perform a defrosting operation to melt the frost attached to the indoor heat exchanger 5.

For example, the operation control unit 51b closes the second on-off valve 6 during dehumidification operation. The operation control unit 51b may fully close the second expansion valve 9 during the dehumidification operation. In this way, it is possible to prevent the refrigerant from flowing into the main circuit 31 from the cooling circuit 32. Further, the operation control unit 51b closes the first on-off valve 2 during the cooling operation. The operation control unit 51b may fully close the first expansion valve 4 during the cooling operation. In this way, the refrigerant remaining in the reheater 3 or the like can be prevented from flowing into the indoor heat exchanger 5.

Furthermore, when surplus refrigerant is generated, the operation control unit 51b causes the air conditioner 100 to perform a refrigerant amount adjustment operation, which will be described later. That is, when the detection signal is output from the surplus refrigerant detection part 51c, the operation control part 51b performs refrigerant amount adjustment control to store the surplus refrigerant in the liquid reservoir 8 while maintaining the performance of the reheater 3. Furthermore, when the refrigerant does not move due to a pressure difference between the outside and the inside, the operation control unit 51b performs refrigerant amount adjustment control according to each situation.

Further, when a refrigerant leak is detected by the indoor refrigerant leak sensor 41, that is, when an indoor leak signal is output from the leak processing section 51d, the operation control section 51b closes the first on-off valve 2 and closes the second on-off valve 2. Fully close the expansion valve 9. As a result, the refrigerant flowing from the first connection part M to the reheater 3 can be cut off, and the indoor refrigerant can be stored in the outdoor heat exchanger 7 and the liquid reservoir 8 via the second on-off valve 6. It is possible to suppress leakage of refrigerant to. The operation control unit 51b may fully close the first expansion valve 4 when the indoor refrigerant leak sensor 41 detects refrigerant leakage. In this way, it is possible to prevent the refrigerant remaining in the reheater 3 or the like from flowing into the indoor heat exchanger 5 side. Therefore, when a refrigerant leakage point exists in the flow path from the second connection part N through the indoor heat exchanger 5 and compressor 1 to the first connection part M, further leakage of refrigerant into the room can be suppressed. I can do it. Note that when the indoor refrigerant leak sensor 41 detects refrigerant leakage, the operation control unit 51b fully closes the first on-off valve 2 and the first expansion valve 4, and closes the first on-off valve 2 of the refrigerant circuit 30. By making the portion from the first expansion valve 4 independent, the process of identifying the location of the refrigerant leak may be facilitated.

Further, when a refrigerant leak is detected by the outdoor refrigerant leak sensor 42, that is, when an outdoor leak signal is output from the leak processing section 51d, the operation control section 51b closes the second on-off valve 6 and closes the first on-off valve 6. Fully close the expansion valve 4. Thereby, the flow of the refrigerant to the outdoors can be blocked and the outdoor refrigerant can be stored in the indoor heat exchanger 5, so that leakage of the refrigerant outdoors can be suppressed. Note that when the outdoor refrigerant leak sensor 42 detects refrigerant leakage, the operation control unit 51b fully closes the second on-off valve 6 and the second expansion valve 9, and closes the second on-off valve 6 of the refrigerant circuit 30. By making the portion from the first expansion valve 9 to the second expansion valve 9 independent, the process of identifying the refrigerant leak location may be facilitated.

The storage unit 52 stores an operation program for the control device 50. The storage unit 52 also stores various data related to air conditioning control. For example, the storage unit 52 stores data on settings such as an operating mode, target temperature, and target humidity. The storage unit 52 also stores information on thresholds that serve as standards for detecting generation of surplus refrigerant, such as a subcooling degree threshold, a discharge threshold, a high pressure threshold, or a low pressure threshold. Note that the supercooling degree threshold, the discharge threshold, the high pressure threshold, and the low pressure threshold are set in advance, and can be changed as appropriate.

FIG. 3 is an explanatory diagram showing the state of the refrigerant circuit 30 during dehumidification operation of the air conditioner 100 shown in FIG. 1. FIG. 4 is an explanatory diagram showing the state of the refrigerant circuit 30 during intermediate operation of the air conditioner 100 shown in FIG. 1. FIG. 5 is an explanatory diagram showing the state of the refrigerant circuit 30 during cooling operation of the air conditioner 100 shown in FIG. 1. FIG. 6 is an explanatory diagram showing the state of the refrigerant circuit 30 during defrosting operation of the air conditioner 100 shown in FIG. 1. In FIGS. 3 to 6, on-off valves in an open state are shown in white, and on-off valves in a closed state are shown in black. Furthermore, in FIGS. 3 to 6, the flow of the refrigerant is shown by broken lines with arrows. Valve control and refrigerant flow in each operation mode will be explained with reference to FIGS. 3 to 6.

[Dehumidification operation]
As shown in FIG. 3, during dehumidification operation, the second on-off valve 6 and the third on-off valve 10 are in a closed state, and the first on-off valve 2 is in an open state. That is, when the control device 50 is set to the dehumidifying operation mode, the first on-off valve 2 is opened, and the second on-off valve 6 and the third on-off valve 10 are closed.

Therefore, the high temperature and high pressure gas refrigerant discharged from the compressor 1 flows into the reheater 3 via the discharge pipe (the pipe between the compressor 1 and the outdoor heat exchanger 7). Here, indoor air blown by the indoor blower 11 and passed through the indoor heat exchanger 5 passes through the reheater 3. Therefore, the high-temperature, high-pressure gas refrigerant that has flowed into the reheater 3 exchanges heat with the indoor air passing through the reheater 3, radiates heat, and is condensed and liquefied. Then, the refrigerant flowing out from the reheater 3 passes through the liquid pipe (the pipe between the reheater 3 and the first expansion valve 4), is depressurized at the first expansion valve 4, and becomes a gas-liquid two-phase refrigerant. It flows into the indoor heat exchanger 5. The gas-liquid two-phase refrigerant that has flowed into the indoor heat exchanger 5 absorbs heat by exchanging heat with the indoor air blown by the indoor blower 11, becomes gasified, and returns to the compressor 1 as a low-temperature, low-pressure gas refrigerant.

Here, the air circulating through the indoor unit 70 by the indoor blower 11 is cooled by the low-temperature, low-pressure gas-liquid two-phase refrigerant flowing through the indoor heat exchanger 5, and its temperature drops to below the dew point. As a result, moisture in the indoor air condenses on the surface of the indoor heat exchanger 5, and the indoor air is dehumidified. Thereafter, the air that has passed through the indoor heat exchanger 5 is heated by a high-temperature, high-pressure gas refrigerant in the reheater 3, increasing its temperature and decreasing its relative humidity.

In this way, the air conditioner 100 radiates all of the heat within the refrigeration cycle indoors by closing the second on-off valve 6 during the dehumidification operation. That is, the air conditioner 100 operates to heat indoor air by the amount of heat added to the refrigerant by the compressor 1 and the latent heat of condensation of water vapor in the air. Therefore, the indoor air sucked into the air conditioner 100 during dehumidification operation is heated and dehumidified at the same time.

[Intermediate operation]
As shown in FIG. 4, during intermediate operation in which the air in the conditioned space is simultaneously dehumidified and cooled, the first on-off valve 2 and the second on-off valve 6 are in the open state, and the third on-off valve 10 is in the closed state. be. That is, when the control device 50 is set to the intermediate operation mode, the first on-off valve 2 and the second on-off valve 6 are opened, and the third on-off valve 10 is closed.

Therefore, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 7 and the reheater 3 via the discharge pipe. Then, the refrigerant that has radiated heat and liquefied in the outdoor heat exchanger 7 and the reheater 3 is transferred to liquid piping (the piping between the outdoor heat exchanger 7 and the second expansion valve 9, and the piping between the reheater 3 and the first expansion valve). The pressure is reduced by the second expansion valve 9 and the first expansion valve 4, which are installed downstream of the piping between 4 and 4, respectively, and the refrigerant becomes a gas-liquid two-phase refrigerant. flows into. The gas-liquid two-phase refrigerant that has flowed into the indoor heat exchanger 5 absorbs heat and is gasified by the indoor heat exchanger 5, and then passes through the suction pipe (the pipe between the indoor heat exchanger 5 and the compressor 1) to the compressor 1. is inhaled. During intermediate operation, the control device 50 performs on/off control on the outdoor blower 12 according to the outdoor temperature and high pressure, and also controls the indoor blower 11 to be turned on at all times. During intermediate operation during refrigerant amount adjustment control, the fan rotation speed is controlled according to the internal liquid SC and external liquid SC. Here, the internal liquid SC refers to the degree of subcooling of the reheater 3, and the external liquid SC refers to the degree of subcooling of the outdoor heat exchanger 7.

[Cooling operation]
As shown in FIG. 5, during the cooling operation to cool the air in the air-conditioned space, the second on-off valve 6 is in the open state, and the first on-off valve 2 and the third on-off valve 10 are in the closed state. That is, when the control device 50 is set to the cooling operation mode, the second on-off valve 6 is opened, and the first on-off valve 2 and the third on-off valve 10 are closed.

Therefore, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 7 through the discharge pipe, exchanges heat with the outdoor air blown by the outdoor blower 12, radiates heat, and condenses to liquefy. do. Then, the refrigerant flowing out from the outdoor heat exchanger 7 passes through the liquid pipe (the pipe between the outdoor heat exchanger 7 and the second expansion valve 9), is depressurized at the second expansion valve 9, and becomes a gas-liquid two-phase refrigerant. , flows into the indoor heat exchanger 5. The gas-liquid two-phase refrigerant flowing into the indoor heat exchanger 5 exchanges heat with the indoor air blown by the indoor blower 11, absorbs heat, becomes gasified, and returns to the compressor 1 as a low-temperature, low-pressure gas refrigerant. That is, the air circulated by the indoor blower 11 is cooled in the indoor heat exchanger 5 by a low-temperature, low-pressure gas-liquid two-phase refrigerant. Note that the surplus refrigerant during the cooling operation is stored in the liquid reservoir 8 as appropriate.

Here, the cooling operation is preferably performed when the indoor absolute humidity is low or when lowering the indoor temperature is a high priority. This is because when the temperature of the air decreases due to cooling operation, the relative humidity increases. This is because, as the relative humidity increases, comfort decreases and dew condensation tends to occur indoors. Also, for example, when the temperature of the air decreases to below the dew point due to cooling operation, moisture in the indoor air condenses on the surface of the indoor heat exchanger 5, increasing ventilation resistance and reducing heat exchange capacity. It is.

[Defrosting operation]
The defrosting operation is an operation performed when frost forms on the indoor heat exchanger 5 and its performance as a heat exchanger deteriorates. As shown in FIG. 6, during the defrosting operation, the first on-off valve 2 and the second on-off valve 6 are in a closed state, and the third on-off valve 10 is in an open state. That is, when the control device 50 is set to the defrosting operation mode, the first on-off valve 2 and the second on-off valve 6 are closed, and the third on-off valve 10 is opened. Therefore, the high temperature and high pressure gas refrigerant discharged from the compressor 1 passes through the discharge pipe and the bypass circuit 33, is depressurized by the first expansion valve 4, and flows into the indoor heat exchanger 5.

Here, the indoor heat exchanger 5 is heated by the refrigerant and exchanges heat with the frost that has formed to melt the frost. The refrigerant that has flowed into the indoor heat exchanger 5 is lowered in temperature by heat exchange with the frost, and then exchanges heat with the suction pipe to absorb heat and gasify, becoming a low-temperature, low-pressure gas refrigerant that is compressed. Return to machine 1. At this time, the control device 50 adjusts the amount of refrigerant passing through the indoor heat exchanger 5 by setting the first expansion valve 4 to the minimum opening degree, thereby preventing liquefied refrigerant from entering the compressor 1. Further, the control device 50 turns off the indoor blower 11. Therefore, during the defrosting operation, only heat exchange between the refrigerant passing through the indoor heat exchanger 5 and the frost adhering to the indoor heat exchanger 5 is performed.

Of the above operations, the intermediate operation shown in FIG. 4 requires a relatively large amount of refrigerant because the refrigerant flows through the reheater 3 and the outdoor heat exchanger 7. On the other hand, the dehumidifying operation shown in FIG. 3 requires less refrigerant than the intermediate operation. This is because, in the dehumidifying operation, refrigerant flows into the reheater 3 but does not flow into the outdoor heat exchanger 7. Therefore, during dehumidification operation, surplus refrigerant may be generated. When excess refrigerant is generated, there is a risk that abnormalities such as an increase in high pressure may occur. Further, when there is a large temperature difference between the outdoors and the indoors, there is a risk that surplus refrigerant will be generated during cooling operation and dehumidification operation due to unevenness of refrigerant.

Therefore, the air conditioner 100 according to the first embodiment performs operation switching control for the purpose of leveling the refrigerant before shifting to the cooling operation or the dehumidifying operation. Furthermore, after each operation is started, refrigerant distribution control is performed based on the state values during operation. First, the operation switching control performed by the operation control section 51b before shifting to the cooling operation or the dehumidification operation will be described.

[Operation switching control]
FIG. 7 is a flowchart illustrating operation switching control of the air conditioner 100 shown in FIG. 1.

The operation control unit 51b performs operation switching control for the purpose of leveling the refrigerant when switching to cooling operation or dehumidification operation. An example of the timing to perform the operation switching control is the timing to shift from the cooling operation to the dehumidifying operation or from the dehumidifying operation to the cooling operation. In other words, when the cooling operation is running, the room becomes cold but the relative humidity increases, so when the humidity exceeds a certain level, a trigger is generated to switch to the dehumidifying operation, whereas when the dehumidifying operation is running, the relative humidity decreases but the relative humidity increases. When the temperature rises and exceeds a certain temperature, a trigger to switch to cooling operation is generated, so operation switching control is performed in response to that trigger.

The operation control unit 51b executes the intermediate operation shown in FIG. 4, opens both the first on-off valve 2 and the second on-off valve 6, and closes the third on-off valve 10 (step S101). The operation control unit 51b then performs operation switching control using the first expansion valve 4 provided downstream of the reheater 3 and the second expansion valve 9 provided downstream of the outdoor heat exchanger 7. do. In the operation switching control, the operation control unit 51b performs SH control on the first expansion valve 4 and performs internal liquid SC control on the second expansion valve 9, for example.

The operation control unit 51b controls the degree of supercooling of the refrigerant condensed in the outdoor heat exchanger 7 using the second expansion valve 9 provided downstream of the outdoor heat exchanger 7, thereby reducing the outdoor heat. The amount of refrigerant distributed in the exchanger 7 is brought into an appropriate state. In addition, by controlling the SH (degree of superheating) of the refrigerant that evaporated and flowed out in the indoor heat exchanger 5 using the first expansion valve 4 provided downstream of the reheater 3, liquid back due to surplus refrigerant can be prevented. At the same time, the refrigerant is stored in the reheater 3 and the outdoor heat exchanger 7.

The operation control unit 51b ends the operation switching control and shifts to the cooling operation or the dehumidification operation when the external liquid SC and the intake SH satisfy the determination values or when the operation time has elapsed for a predetermined time. Specifically, the operation control unit 51b ends the operation switching control when the external liquid SC≒5K and the suction SH≒5K are satisfied (YES in step S102) or when the operating time has elapsed for 5 minutes (YES in step S103). and shifts to cooling operation or dehumidification operation (step S104). At this time, regarding step S102, the determination values for the external fluid SC and the inhalation SH are 5K, but may have a range of ±α. In other words, the external fluid SC and the inhaled SH do not have to completely match the determination value of 5K, and the conditions are also satisfied even if 5-αK≦external solution SC and SH≦5+αK. Here, the suction SH refers to the degree of superheat on the suction side of the compressor 1. Regarding step S103, although the operation switching control can standardize the refrigerant, it will result in half-hearted operation, so we do not want to do it for too long, and since it can be considered that the operation has been leveled to some extent after 5 minutes, the operation time It is determined whether 5 minutes have passed.

FIG. 8 is a flowchart illustrating refrigerant distribution control during cooling operation of the air conditioner 100 shown in FIG. 1. Next, the refrigerant distribution control performed based on the state value during operation after shifting to each operation will be explained.

Refrigerant distribution control is determined from the state value during operation and executed when the above-mentioned operation switching control is executed and the operation is switched to cooling operation or dehumidification operation.

[Refrigerant distribution control during cooling operation]
The operation control unit 51b determines whether the amount of refrigerant in the cooling operation is excessive or insufficient using the external liquid SC (step S201).

(When external liquid SC≦5K (refrigerant shortage))
When the external liquid SC≦5K (NO in step S201), the operation control unit 51b determines that there is a refrigerant shortage, and moves to the next determination formula. In the following determination formula, the outdoor condensing temperature CTout, which is the condensing temperature of the outdoor heat exchanger 7, is set to a value CTout_max - at which high pressure protection control, which is control to lower the frequency of the compressor 1 or stop the compressor 1, is implemented. It is determined whether the internal liquid temperature, which is the temperature of the refrigerant flowing through the reheater 3, is higher than the evaporation temperature ET, which is the evaporation temperature of the indoor heat exchanger 5 (step S209). ). This is because the determination formula for the outdoor condensing temperature CTout is intended to prevent high pressure abnormalities when the distribution of refrigerant is increased toward the outdoor side, and the determination formula for the evaporation temperature ET is intended to prevent high pressure abnormalities from occurring from the indoor side described below. When discharging the refrigerant, it is determined whether or not the refrigerant can be discharged based on the differential pressure. When the operation control unit 51b determines that it is difficult to discharge the refrigerant from the indoor side without satisfying the above-mentioned determination formula (NO in step S209), the operation control unit 51b performs further refrigerant amount adjustment operation by intermediate operation (step S213). This is to forcibly circulate the refrigerant, which has become difficult to discharge from the indoor side due to the pressure difference, so that it becomes the intended external liquid SC.

In the intermediate operation at this time, the second expansion valve 9 performs SH control, and the first expansion valve 4 performs internal liquid SC control. At the same time, the rotational speed of the outdoor blower 12 is lowered to increase the external liquid SC. This is done by performing internal liquid SC control with the first expansion valve 4, which opens the refrigerant and discharges the refrigerant accumulated in the reheater 3, and by performing SH control with the second expansion valve 9, the refrigerant The purpose is to make it easier to store the refrigerant in the liquid reservoir 8 and the outdoor heat exchanger 7, and to forcibly circulate the refrigerant that could not be discharged due to the pressure difference. If the operation control unit 51b determines that the external liquid SC≈5K is satisfied (YES in step S214), it ends this control (step S215).

When the operation control unit 51b determines that the above-mentioned determination formula is satisfied and the refrigerant can be discharged from the indoor side (YES in step S209), the operation control unit 51b changes the control target of the first expansion valve 4 to external liquid SC≈5K (step S210). , the first expansion valve 4 is opened from the closed state to the minimum opening degree, and control is performed so that the external liquid SC≈5K. When the operation control unit 51b determines that the external liquid SC≈5K is satisfied (YES in step S211), the operation control unit 51b fully closes the first expansion valve 4 and ends this control (step S212). Note that by not executing this control for a certain period of time after executing this control, it is possible to prevent deterioration of the first expansion valve 4 caused by frequently adjusting the opening from fully closed, and to reduce reliability. prevent.

(When external liquid SC>5K (excessive refrigerant))
When the external liquid SC>5K (YES in step S201), the operation control unit 51b determines that there is an excess of refrigerant, and moves to the next determination formula. In the next determination formula, it is determined whether the outdoor condensation temperature CTout satisfies the requirement that it is higher than the internal liquid temperature (step S202). This is to determine whether or not the refrigerant can be discharged based on the differential pressure when discharging the refrigerant from the outdoor side, which will be described next. When the operation control unit 51b determines that it is difficult to discharge the refrigerant from the indoor side without satisfying the above-mentioned determination formula (NO in step S202), the operation control unit 51b performs further refrigerant amount adjustment operation by intermediate operation (step S206). This is to forcibly circulate the refrigerant that has become difficult to discharge due to the differential pressure, so that it becomes the intended external liquid SC.

In the intermediate operation at this time, the second expansion valve 9 performs SC control of the external liquid, and the first expansion valve 4 performs SH control. At the same time, the rotation speed of the indoor blower 11 is lowered to increase the internal liquid SC. This is achieved by performing external liquid SC control with the second expansion valve 9, which opens the second expansion valve 9 and discharges the refrigerant accumulated in the outdoor heat exchanger 7, and by performing SH control with the first expansion valve 4. The purpose of this system is to facilitate the storage of refrigerant in the reheater 3 and to forcefully circulate the refrigerant that could not be discharged due to the pressure difference. If the operation control unit 51b determines that the external liquid SC≈5K has been filled (YES in step S207), it ends this control (step S208).

If the operation control unit 51b determines that the above-mentioned determination formula is satisfied and the refrigerant can be discharged from the indoor side (YES in step S202), the operation control unit 51b opens the first on-off valve 2 (step S203). This is intended to store refrigerant in the reheater 3. Then, the operation control unit 51b performs control to open the first expansion valve 4 from the closed state to the minimum opening degree so that the external liquid SC≈5K. When the operation control unit 51b determines that the external liquid SC≈5K is satisfied (YES in step S204), the operation control unit 51b fully closes the first on-off valve 2 and ends this control (step S205). Note that by not executing this control for a certain period of time after executing this control, it is possible to prevent deterioration of the first on-off valve 2 due to frequent opening and closing, and to prevent deterioration of reliability.

[Refrigerant distribution control during dehumidification operation]
FIG. 9 is a flowchart illustrating refrigerant distribution control during dehumidification operation of the air conditioner 100 shown in FIG. 1.

The operation control unit 51b determines whether the amount of refrigerant in the dehumidifying operation is excessive or insufficient in the internal liquid SC (step S301).

(In case of internal liquid SC<5K (refrigerant shortage))
When the internal liquid SC<5K (NO in step S301), the operation control unit 51b determines that there is a refrigerant shortage, and moves to the next determination formula. In the following judgment formula, the indoor condensing temperature CTin, which is the condensing temperature of the reheater 3, is lower than the value CTin_max - 5K at which high pressure protection control is implemented, and the temperature of the refrigerant flowing through the outdoor heat exchanger 7. It is determined whether the external liquid temperature is higher than the evaporation temperature ET (step S309). This is because the determination formula for the indoor condensation temperature CTin is intended to prevent high pressure abnormalities when the distribution of refrigerant is increased indoors, and the determination formula for the evaporation temperature ET is intended to prevent high pressure abnormalities from occurring when the refrigerant is distributed indoors. When discharging the refrigerant, it is determined whether or not the refrigerant can be discharged based on the differential pressure. When the operation control unit 51b determines that it is difficult to discharge the refrigerant from the outdoor side without satisfying the above-mentioned determination formula (NO in step S309), the operation control unit 51b performs further refrigerant amount adjustment operation by intermediate operation (step S313). This is to forcibly circulate the refrigerant that has become difficult to discharge due to the differential pressure, so that it becomes the intended internal liquid SC.

In the intermediate operation at this time, the second expansion valve 9 performs SC control of the external liquid, and the first expansion valve 4 performs SH control. At this time, the rotation speed of the indoor blower 11 is lowered to increase the internal liquid SC. This is done by performing external liquid SC control with the second expansion valve 9, which opens the second expansion valve 9 and discharges the refrigerant accumulated in the outdoor heat exchanger 7, and by performing SH control with the first expansion valve 4. The purpose is to facilitate the circulation of a large amount of refrigerant to the reheater 3, and to forcibly circulate the refrigerant that could not be discharged due to the pressure difference. If the operation control unit 51b determines that the internal liquid SC≈5K is satisfied (YES in step S314), it ends this control (step S315).

When the operation control unit 51b determines that the above-mentioned determination formula is satisfied and the refrigerant can be discharged from the outdoor side (YES in step S309), the operation control unit 51b changes the control target of the second expansion valve 9 to internal liquid SC≈5K (step S310). , the second expansion valve 9 is opened from the closed state to the minimum opening degree, and control is performed so that the internal liquid SC≈5K. When the operation control unit 51b determines that the internal liquid SC≈5K is satisfied (YES in step S311), the operation control unit 51b fully closes the second expansion valve 9 and ends this control (step S312). Note that by not executing this control for a certain period of time after executing this control, it is possible to prevent deterioration of the second expansion valve 9 caused by frequently adjusting the opening from fully closed, and to reduce reliability. prevent.

(In case of internal liquid SC>5K (excessive refrigerant))
When the internal liquid SC>5K (YES in step S301), the operation control unit 51b determines that there is an excess of refrigerant, and moves on to the next determination formula. In the next determination formula, it is determined whether the indoor condensation temperature CTin is higher than the outside liquid temperature (step S302). This is to determine whether or not the refrigerant can be discharged based on the differential pressure when discharging the refrigerant from the outdoor side, which will be described next. When the operation control unit 51b determines that it is difficult to discharge the refrigerant from the outdoor side without satisfying the above-mentioned determination formula (NO in step S302), the operation control unit 51b performs further refrigerant amount adjustment operation by intermediate operation (step S306). This is to forcibly circulate the refrigerant that has become difficult to discharge due to the differential pressure, so that it becomes the intended internal liquid SC.

In the intermediate operation at this time, the second expansion valve 9 performs SH control, and the first expansion valve 4 performs internal liquid SC control. At this time, the rotation speed of the indoor blower 11 is increased to reduce the internal liquid SC. At the same time, the rotational speed of the outdoor blower 12 is lowered to increase the external liquid SC. This is done by performing internal liquid SC control with the first expansion valve 4, which opens the refrigerant and discharges the refrigerant accumulated in the reheater 3, and by performing SH control with the second expansion valve 9, the refrigerant The purpose is to make it easier to store the refrigerant in the liquid reservoir 8 and the outdoor heat exchanger 7, and to forcibly circulate the refrigerant that could not be discharged due to the pressure difference. If the operation control unit 51b determines that the internal liquid SC≈5K is satisfied (YES in step S307), it ends this control (step S308).

When the operation control unit 51b determines that the above-mentioned determination formula is satisfied and the refrigerant can be discharged from the outdoor side (YES in step S302), the operation control unit 51b opens the second on-off valve 6 (step S303). This is intended to store refrigerant in the outdoor heat exchanger 7. Then, the operation control unit 51b performs control to open the second expansion valve 9 from the closed state to the minimum opening degree so that the internal liquid SC≈5K. When the operation control unit 51b determines that the internal liquid SC≈5K is satisfied (YES in step S304), the operation control unit 51b fully closes the second on-off valve 6 and ends this control (step S305). Note that by not executing this control for a certain period of time after executing this control, it is possible to prevent deterioration of the second on-off valve 6 due to frequent opening and closing, and to prevent deterioration in reliability.

For both the refrigerant distribution control during cooling operation and the refrigerant distribution control during dehumidification operation, a range is set as a target for the SC determination value at the end, and it is assumed that they do not need to match completely. That is, for steps S204, S207, S211, S214, S304, S307, S311, and S314, the determination value of external fluid SC or internal fluid SC is 5K, but may have a range of ±α. In other words, the external fluid SC or the internal fluid SC does not have to completely match the determination value of 5K, and the condition is satisfied even if 5-αK≦external fluid SC or internal fluid SC≦5+αK.

Furthermore, in steps S204, S207, S211, S214, and steps S304, S307, S311, and S314, even if the conditions are not satisfied, the process may proceed to YES if a preset time has elapsed.

The operation control unit 51b according to the first embodiment adjusts the amount of refrigerant to an appropriate value through the operation switching control and refrigerant distribution control described above. Therefore, in the dehumidifying operation, the reheat amount of the reheater 3 required during the dehumidifying operation can be secured and the necessary and sufficient dehumidifying capacity can be demonstrated, and in the cooling operation, the condensation of the outdoor heat exchanger 7 required during the cooling operation can be It is possible to secure sufficient amount of cooling capacity and exhibit the necessary and sufficient cooling capacity. In addition, even in situations where it is determined that it is difficult to discharge the refrigerant from the outside or inside due to the pressure difference, the refrigerant is forcibly circulated in intermediate operation to transition the state to the intended refrigeration cycle and maintain the ideal cooling capacity. able to demonstrate.

More specifically, during operation switching control, the operation control unit 51b controls the opening degree of the second expansion valve 9 by using, for example, the temperature of the refrigerant at the outlet of the outdoor heat exchanger 7. That is, the operation control unit 51b uses the outdoor heat exchanger outlet temperature measured by the refrigerant temperature sensor 69 to determine the degree of subcooling of the outdoor heat exchanger 7. When determining the degree of subcooling of the outdoor heat exchanger 7, the operation control unit 51b acquires the high pressure from the pressure sensor 62 and also acquires the outdoor heat exchanger outlet temperature measured by the refrigerant temperature sensor 69. Then, the operation control unit 51b calculates the condensation temperature by converting the high pressure into saturation, and subtracts the outdoor heat exchanger outlet temperature from the condensation temperature to determine the degree of supercooling of the outdoor heat exchanger 7. The operation control unit 51b then controls the second expansion valve 9 according to the obtained degree of supercooling. Thereby, the amount of refrigerant distributed in the outdoor heat exchanger 7 is adjusted. Note that the condensation temperature may be a value converted to saturation from the pressure sensor 64.

Further, the operation control unit 51b performs SH control of the first expansion valve 4 so as to maintain the degree of superheating by the reheater 3 at or above the determination value. As a result, surplus refrigerant is stored in the liquid reservoir 8, and liquid backflow to the compressor 1 is suppressed. In the first embodiment, when determining the degree of superheating of the indoor heat exchanger 5, the operation control unit 51b acquires the low pressure from the pressure sensor 61 and the suction temperature from the refrigerant temperature sensor 65. Then, the operation control unit 51b calculates the evaporation temperature ET by converting the low pressure into saturation, and subtracts the evaporation temperature ET from the suction temperature to calculate the degree of superheating of the indoor heat exchanger 5. However, a refrigerant temperature sensor (not shown) may be provided in the middle of the indoor heat exchanger 5, and the temperature measured by the refrigerant temperature sensor may be used as the evaporation temperature ET.

During refrigerant distribution control during cooling operation, the operation control unit 51b controls the opening degree of the second expansion valve 9 by using, for example, the temperature of the refrigerant at the outlet of the outdoor heat exchanger 7. That is, the operation control unit 51b uses the outdoor heat exchanger outlet temperature measured by the refrigerant temperature sensor 69 to determine the degree of subcooling of the outdoor heat exchanger 7. When determining the degree of subcooling of the outdoor heat exchanger 7 , the operation control unit 51 b acquires the high pressure from the pressure sensor 62 and acquires the outdoor heat exchanger outlet temperature from the refrigerant temperature sensor 69 . Then, the operation control unit 51b calculates the condensation temperature by converting the high pressure into saturation, and subtracts the outdoor heat exchanger outlet temperature from the condensation temperature to determine the degree of supercooling of the outdoor heat exchanger 7. Then, the operation control unit 51b controls the second expansion valve 9 according to the obtained degree of supercooling, and also controls the first on-off valve 2, the second on-off valve 6, and the first expansion valve 4. The amount of refrigerant distributed in the outdoor heat exchanger 7 is adjusted. Note that the condensation temperature may be a value converted to saturation from the pressure sensor 64.

During refrigerant distribution control during dehumidification operation, the operation control unit 51b controls the opening degree of the first expansion valve 4 using, for example, the temperature of the refrigerant at the outlet of the reheater 3. That is, the operation control unit 51b uses the reheater outlet temperature measured by the refrigerant temperature sensor 67 to determine the degree of subcooling of the reheater 3. When determining the degree of subcooling of the reheater 3, the operation control unit 51b acquires the high pressure from the pressure sensor 62 and acquires the reheater outlet temperature from the refrigerant temperature sensor 67. Then, the operation control unit 51b calculates the condensation temperature by converting the high pressure into saturation, and subtracts the reheater outlet temperature from the condensation temperature to determine the degree of supercooling of the reheater 3. Then, the operation control unit 51b controls the first expansion valve 4 according to the obtained degree of supercooling, and also controls the second on-off valve 6, the third on-off valve 10, and the second expansion valve 9. The amount of refrigerant distributed in the reheater 3 is adjusted. Note that the condensation temperature may be a value converted to saturation from the pressure sensor 63.

[Processing and operation in case of refrigerant leak]
FIG. 10 is a diagram illustrating an example of the operation details of each on-off valve and each expansion valve when a refrigerant leaks in the air conditioner 200 according to the first embodiment.

Next, an example of the processing content by the control device 50 when a refrigerant leak occurs and the operation content of each on-off valve and each expansion valve will be explained.

(When indoor refrigerant leak sensor 41 detects refrigerant leak)
When the indoor refrigerant leak sensor 41 detects a refrigerant leak, as shown in FIG. 10, the control device 50 closes the first on-off valve 2, opens the second on-off valve 6, and closes the third on-off valve 10. is closed, the first expansion valve 4 is fully opened, the second expansion valve 9 is fully closed, and the compressor 1 is operated to perform pump-down operation. When performing the pump-down operation, the control device 50 preferably makes the rotation speeds of the indoor blower 11 and the outdoor blower 12 larger than the rotation speeds during normal operation. This is to increase the amount of air flow and diffuse the leaked refrigerant so that the leaked refrigerant does not create a high concentration area. Due to the valve control and pump down operation as described above, when refrigerant leaks indoors, the refrigerant is transferred to the pipes from the second on-off valve 6 to the outdoor heat exchanger 7, the outdoor heat exchanger 7, and the outdoor heat exchanger. The liquid can be stored in the piping from the liquid reservoir 7 to the liquid reservoir 8, the liquid reservoir 8, and the piping from the liquid reservoir 8 to the second expansion valve 9.

The control device 50 also controls the operation of the compressor 1 when the pressure on the suction side of the compressor 1 becomes lower than the set value or when the pressure on the discharge side of the compressor 1 becomes higher than the set value. to stop. After stopping the operation of the compressor 1, the control device 50 closes the second on-off valve 6. In this way, by closing the second on-off valve 6 after the compressor 1 is stopped, it is possible to suppress the backflow of the refrigerant. As described above, safety can be improved by stopping the operation of the air conditioner 100 in stages.

In addition, after executing the pump-down operation, if there is no problem in circulating the refrigerant among the compressor 1, outdoor heat exchanger 7, second expansion valve 9, and indoor heat exchanger 5, the second on-off valve 6 is turned on. Cooling operation can be carried out by opening. By performing the cooling operation, it is possible to prevent a rise in the temperature of the air-conditioned space, so it is possible to suppress a decrease in comfort. Note that the situation in which there is no problem even if the refrigerant is circulated between the compressor 1, the outdoor heat exchanger 7, the second expansion valve 9, and the indoor heat exchanger 5 is that the refrigerant leakage point is between the first on-off valve 2 and the A case is assumed in which it is specified between the first expansion valve 4 or between the third on-off valve 10 and the first expansion valve 4.

(When the outdoor refrigerant leak sensor 42 detects refrigerant leak)
When the outdoor refrigerant leak sensor 42 detects a refrigerant leak, as shown in FIG. 10, the control device 50 opens the first on-off valve 2, closes the second on-off valve 6, and closes the third on-off valve 10. is closed, the first expansion valve 4 is fully closed, the second expansion valve 9 is fully open, and the compressor 1 is operated to perform pump-down operation. When performing the pump-down operation, the control device 50 preferably makes the rotation speeds of the indoor blower 11 and the outdoor blower 12 larger than the rotation speeds during normal operation. Due to the valve control and pump down operation as described above, when a refrigerant leak occurs outdoors, the refrigerant is removed from the piping from the first on-off valve 2 to the reheater 3, the reheater 3, and the reheater 3. It can be stored in the piping up to the first expansion valve 4.

The control device 50 also controls the operation of the compressor 1 when the pressure on the suction side of the compressor 1 becomes lower than the set value or when the pressure on the discharge side of the compressor 1 becomes higher than the set value. to stop. After stopping the operation of the compressor 1, the control device 50 closes the first on-off valve 2. In this way, by closing the first on-off valve 2 after the compressor 1 is stopped, it is possible to suppress the backflow of the refrigerant. As described above, safety can be improved by stopping the operation of the air conditioner 100 in stages.

In addition, after executing the pump-down operation, if there is no problem in circulating the refrigerant among the compressor 1, reheater 3, first expansion valve 4, and indoor heat exchanger 5, the first on-off valve 2 is turned on. It is possible to carry out dehumidification operation by opening the door. By continuing the dehumidifying operation, it is possible to prevent an increase in the humidity in the air-conditioned space, so it is possible to suppress a decrease in comfort. Note that in a situation where there is no problem even if the refrigerant is circulated among the compressor 1, reheater 3, first expansion valve 4, and indoor heat exchanger 5, the refrigerant leakage point is between the second on-off valve 6 and the second on-off valve 6. A case is assumed in which it is specified between the two expansion valves 9, etc.

As described above, in the air conditioner 100 according to the first embodiment, the control device 50 closes the second on-off valve 6 during the dehumidification operation, so that the refrigerant does not accumulate in the outdoor heat exchanger 7. Since this can be prevented, dehumidification ability can be suppressed from decreasing, and dehumidification operation can be performed efficiently. Further, the control device 50 may fully close the second expansion valve 9 during the dehumidification operation. In this way, it is possible to prevent the refrigerant from flowing into the main circuit 31 from the cooling circuit 32, thereby increasing the efficiency of the dehumidifying operation.

Further, the main circuit 31 performs an opening/closing operation between the first connection part M, which is the connection part between the main pipe 21 and the cooling pipe 22 between the compressor 1 and the reheater 3, and the reheater 3. It has a first opening/closing valve 2 that operates. The control device 50 is configured to close the first on-off valve 2 during cooling operation. Therefore, since it is possible to prevent the refrigerant from flowing into the reheater 3, it is possible to smooth the refrigerant circulation during the cooling operation and improve the operating efficiency. In addition, the control device 50 may fully close the first expansion valve 4 during the cooling operation. In this way, the refrigerant remaining in the flow path from the first connection part M to the second connection part N via the reheater 3 and the first expansion valve 4 is prevented from flowing into the indoor heat exchanger 5. Since this can be prevented, the operating efficiency during cooling operation can be further improved.

Further, when a refrigerant leak is detected by the indoor refrigerant leak sensor 41, the control device 50 closes the first on-off valve 2 and fully closes the second expansion valve 9. Therefore, the refrigerant can be prevented from flowing into the main circuit 31 provided indoors, and the refrigerant can be stored in the outdoor heat exchanger 7 and the liquid reservoir 8, so that leakage of the refrigerant into the room can be suppressed. In addition, the control device 50 may fully close the first expansion valve 4 when the indoor refrigerant leak sensor 41 detects refrigerant leakage. In this way, it is possible to prevent the refrigerant stagnant in the reheater 3 etc. from flowing into the indoor heat exchanger 5, so that the refrigerant leakage point is from the first on-off valve 2 to the reheater 3. If the refrigerant is not on the flow path leading to the first expansion valve 4, leakage of the refrigerant into the room can be reduced. In addition, by closing the first on-off valve 2, the third on-off valve 10, and the first expansion valve 4, and making the part of the refrigerant circuit 30 from the first on-off valve 2 to the first expansion valve 4 independent, the refrigerant The process of identifying the location of the leak may be facilitated.

Furthermore, when a refrigerant leak is detected by the outdoor refrigerant leak sensor 42, the control device 50 closes the second on-off valve 6 and fully closes the first expansion valve 4. Thereby, the flow of the refrigerant to the outside can be blocked, and the refrigerant from the outside can be stored in the indoor heat exchanger 5, so that leakage of the refrigerant to the outside can be suppressed. In addition, the control device 50 may fully close the second expansion valve 9 when the outdoor refrigerant leak sensor 42 detects refrigerant leakage. In this way, the portion of the refrigerant circuit 30 from the second on-off valve 6 to the second expansion valve 9 can be made independent, and the location of the refrigerant leak can be quickly identified.

By the way, if the operation switching control or the refrigerant distribution control is not performed, the refrigerant tends to flow toward the lower temperature indoors or outdoors. In other words, unless operation switching control or refrigerant distribution control is performed, when the indoor temperature is lower than the outdoor temperature, the refrigerant will flow more easily to the reheater 3, so the indoor temperature will not rise above the desired temperature. , the relative humidity drops below the desired humidity. On the other hand, when the outdoor temperature is lower than the indoor temperature, it becomes difficult for the refrigerant to flow to the reheater 3, so the indoor temperature falls below the desired target temperature and the relative humidity rises above the desired humidity. . In this regard, the control device 50 can adjust the refrigerant distribution to an appropriate amount as described above. Therefore, the amount of heating by the reheater 3 can be ensured, and the indoor unit 70 can exhibit its dehumidifying ability.

Further, if only the second expansion valve 9 is controlled to keep the degree of subcooling of the outdoor heat exchanger 7 above the determination value, there is a risk that liquid back will occur. This is because the surplus refrigerant cannot be reduced by controlling only the second expansion valve 9. In this regard, as described above, the control device 50 executes the SH control of the first expansion valve 4 so as to maintain the degree of superheating by the reheater 3 at or above the determination value, and adjusts the degree of superheating by the outdoor heat exchanger 7 to the determination value. SH control (only part of the refrigerant amount adjustment control) of the second expansion valve 9 is performed so as to maintain the above value. As a result, the surplus refrigerant is stored in the liquid reservoir 8, the refrigerant can be stored in the outdoor heat exchanger 7, and it can also be stored in the reheater 3 (only part of the refrigerant amount adjustment control). The occurrence of liquid back can be suppressed. That is, according to the air conditioner 100 according to the first embodiment, the SC control and the SH control (only part of the refrigerant amount adjustment control) at the second expansion valve 9 and the SH control at the first expansion valve 4 are performed. By combining the control and the SC control (only part of the refrigerant amount adjustment control), it is possible to suppress a decrease in reheating capacity and avoid damage to the compressor 1 due to liquid back.

Furthermore, by using a non-azeotropic mixed refrigerant as the refrigerant that is circulated through the refrigerant circuit 30, the temperature at the inlet side of the refrigerant in the indoor heat exchanger 5 becomes lower than the temperature at the outlet side of the refrigerant. Further, in the reheater 3, the temperature on the refrigerant inlet side is higher than the temperature on the refrigerant outlet side. Then, the air that has passed through the refrigerant inlet side of the indoor heat exchanger 5 passes through the refrigerant outlet side of the reheater 3, and the indoor heat exchanger 5 and the reheater 3 The reheater 3 is arranged so that the air that has passed through the refrigerant outlet side of the reheater 5 passes through the refrigerant inlet side of the reheater 3. For example, a portion of the indoor heat exchanger 5 where the refrigerant temperature is relatively low is opposed to a portion of the reheater 3 where the refrigerant temperature is relatively high, and the refrigerant temperature of the indoor heat exchanger 5 is relatively high. and a portion of the reheater 3 where the refrigerant temperature is relatively low are arranged so as to face each other. That is, the indoor heat exchanger 5 and the reheater 3 are both provided so that the refrigerant flows from the top to the bottom. By arranging the indoor heat exchanger 5 and the reheater 3 in this way, variations in the blowout temperature, which is the temperature of the air blown out from the indoor unit 70 into the air-conditioned space, and unevenness in humidity caused by the dispersion in the blowout temperature are reduced. and can be reduced. Therefore, variations in the humidity of the air blown out from the indoor unit 70 into the air-conditioned space can be suppressed, and the state of the indoor air can be stabilized.

As described above, the air conditioner 100 according to the first embodiment includes a main circuit 31 in which the compressor 1 , the first on-off valve 2 , the reheater 3 , the first expansion valve 4 , and the evaporator are sequentially connected by the main pipe 21 . The second on-off valve 6, the condenser, and the second expansion valve 9 are sequentially operated by the cooling pipe 22 that connects between the compressor 1 and the first on-off valve 2 and between the first expansion valve 4 and the evaporator. A bypass circuit having a connected cooling circuit 32, a bypass pipe 23 connecting from the discharge side of the compressor 1 to between the reheater 3 and the first expansion valve 4, and a third on-off valve 10 that opens and closes the bypass pipe 23. 33, a refrigerant circuit 30 in which refrigerant circulates, and a control device 50 for controlling the refrigerant circuit 30, the reheater 3 and the evaporator are arranged in the air-conditioned space, and the condenser is arranged in the air-conditioned space. Arranged externally, the control device 50 controls the first on-off valve 2 and the second on-off valve 6 before switching the operation to a cooling operation that cools the air in the air-conditioned space or a dehumidification operation that dehumidifies the air in the air-conditioned space. the third on-off valve 10 is closed, the first expansion valve 4 is used to control the degree of superheating on the suction side of the compressor 1, and the second expansion valve 9 is used to control the degree of supercooling of the condenser. This is to perform operation switching control.

According to the air conditioner 100 according to the first embodiment, the control device 50 opens the first on-off valve 2 and the second on-off valve 6 and opens the third on-off valve before switching the operation to the cooling operation or the dehumidification operation. Operation switching in which the valve 10 is closed, the first expansion valve 4 is used to control the degree of superheating on the suction side of the compressor 1, and the second expansion valve 9 is used to control the degree of supercooling of the condenser. This is to carry out control. By implementing this operation switching control, the amount of refrigerant is adjusted to an appropriate value, so it is possible to prevent uneven distribution of refrigerant in each heat exchanger before performing cooling operation or dehumidification operation. .

Furthermore, in the air conditioner 100 according to the first embodiment, the control device 50 controls, when the degree of subcooling of the condenser and the degree of superheating of the suction side of the compressor 1 reach preset values during operation switching control. Alternatively, after a preset time has elapsed, the operation is switched to cooling operation or dehumidification operation.

According to the air conditioner 100 according to the first embodiment, after the refrigerant amount is adjusted to an appropriate value, the operation can be switched to the cooling operation or the dehumidification operation at an appropriate timing.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls, during the cooling operation, when the degree of subcooling of the condenser is equal to or less than a preset value, and the condensation temperature of the condenser is If the internal liquid temperature is lower than the value at which high-pressure protection is implemented, which is control to lower the frequency of compressor 1 or stop compressor 1, and higher than the evaporation temperature of the evaporator, the condenser is overheated. Refrigerant distribution control is performed to control the first expansion valve 4 so that the degree of cooling becomes a preset value.

According to the air conditioner 100 according to the first embodiment, during the cooling operation, the amount of condensation of the outdoor heat exchanger 7 required during the cooling operation can be ensured, and the necessary and sufficient cooling capacity can be exhibited. In addition, when adjusting the amount of refrigerant to an appropriate value, it is possible to discharge the refrigerant from the indoor side using differential pressure, and by discharging the refrigerant from the indoor side, the refrigerant distribution can be adjusted to the outdoor side. High pressure abnormalities do not occur when the amount is increased.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls, during the cooling operation, when the degree of subcooling of the condenser is equal to or less than a preset value, and the condensation temperature of the condenser is If the internal liquid temperature is not lower than the value at which high pressure protection, which is control to lower the frequency of the compressor 1 or stop the compressor 1, is implemented, or if the internal liquid temperature is not higher than the evaporation temperature of the evaporator, the first The on-off valve 2 and the second on-off valve 6 are opened, the third on-off valve 10 is closed, the first expansion valve 4 is used to control the degree of supercooling of the reheater 3, and the second expansion valve 9 is closed. This is used to control the degree of superheating on the suction side of the compressor 1, thereby implementing refrigerant distribution control.

According to the air conditioner 100 according to the first embodiment, even in a situation where it is determined that it is difficult to discharge the refrigerant from the indoor side due to the pressure difference during the cooling operation, the intended refrigerant is forcibly circulated in the intermediate operation. The state can be changed to the refrigeration cycle and the ideal cooling capacity can be demonstrated.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls, during the cooling operation, when the degree of subcooling of the condenser is larger than a preset value, the condensation temperature of the condenser is When the temperature is higher than the internal liquid temperature, the first on-off valve 2 is opened and the first expansion valve 4 is controlled so that the degree of supercooling of the condenser becomes a preset value. It is.

According to the air conditioner 100 according to the first embodiment, during the cooling operation, the amount of condensation of the outdoor heat exchanger 7 required during the cooling operation can be ensured, and the necessary and sufficient cooling capacity can be exhibited. Further, in adjusting the amount of refrigerant to an appropriate value, the refrigerant can be discharged from the indoor side using a differential pressure.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls, during the cooling operation, when the degree of subcooling of the condenser is larger than a preset value, the condensation temperature of the condenser is If the temperature is not higher than the internal liquid temperature, the first on-off valve 2 and the second on-off valve 6 are opened, the third on-off valve 10 is closed, and the first expansion valve 4 is used to open the suction side of the compressor 1. The refrigerant distribution control is performed by controlling the degree of superheating and controlling the degree of subcooling of the condenser using the second expansion valve 9.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls the reheater 3 when the degree of subcooling of the reheater 3 is less than or equal to a preset value during the dehumidifying operation. If the condensing temperature is lower than the value at which high pressure protection is implemented, which is control to lower the frequency of the compressor 1 or stop the compressor 1, and the external liquid temperature is higher than the evaporation temperature of the evaporator, Refrigerant distribution control is performed to control the second expansion valve 9 so that the degree of subcooling of the reheater 3 becomes a preset value.

According to the air conditioner 100 according to the first embodiment, during the dehumidifying operation, the reheat amount of the reheater 3 required during the dehumidifying operation can be ensured, and the necessary and sufficient dehumidifying ability can be exhibited. In addition, when adjusting the amount of refrigerant to an appropriate value, it is possible to discharge the refrigerant from the outdoor side using differential pressure, and also to adjust the distribution of the refrigerant to the indoor side by discharging the refrigerant from the outdoor side. High pressure abnormalities do not occur when the amount is increased.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls the reheater 3 when the degree of subcooling of the reheater 3 is less than or equal to a preset value during the dehumidifying operation. The condensing temperature is not lower than the value at which high pressure protection is implemented, which is control to lower the frequency of compressor 1 or stop compressor 1, or the external liquid temperature is not higher than the evaporation temperature of the evaporator. In this case, the first on-off valve 2 and the second on-off valve 6 are opened, the third on-off valve 10 is closed, and the first expansion valve 4 is used to control the degree of superheat on the suction side of the compressor 1. The second expansion valve 9 is used to control the degree of subcooling of the condenser, thereby implementing refrigerant distribution control.

According to the air conditioner 100 according to the first embodiment, even in a situation where it is determined that it is difficult to discharge the refrigerant from the outdoor side due to the pressure difference during the dehumidification operation, the intended refrigerant is forcibly circulated in the intermediate operation. The state can be changed to the refrigeration cycle and the ideal cooling capacity can be demonstrated.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls the reheater 3 when the degree of subcooling of the reheater 3 is larger than a preset value during dehumidification operation. When the condensation temperature is higher than the external liquid temperature, the second on-off valve 6 is opened and the second expansion valve 9 is controlled so that the degree of subcooling of the reheater 3 becomes a preset value. This is to implement distribution control.

According to the air conditioner 100 according to the first embodiment, during the dehumidification operation, the amount of condensation of the reheater 3 required during the dehumidification operation can be ensured, and the necessary and sufficient cooling capacity can be exhibited. Further, in adjusting the amount of refrigerant to an appropriate value, the refrigerant can be discharged from the outdoor side using a differential pressure.

Further, in the air conditioner 100 according to the first embodiment, the control device 50 controls the reheater 3 when the degree of subcooling of the reheater 3 is larger than a preset value during dehumidification operation. When the condensing temperature is not higher than the external liquid temperature, the first on-off valve 2 and the second on-off valve 6 are opened, the third on-off valve 10 is closed, and the first expansion valve 4 is used to operate the reheater. The second expansion valve 9 controls the degree of supercooling on the suction side of the compressor 1, thereby implementing refrigerant distribution control.

Furthermore, the air conditioner 100 according to the first embodiment includes an indoor refrigerant leak sensor 41 that is provided in an air-conditioned space and detects refrigerant leakage, and the control device 50 detects refrigerant leakage at the indoor refrigerant leakage sensor 41. When detected, the first on-off valve 2 is closed.

Furthermore, in the air conditioner 100 according to the first embodiment, the control device 50 brings the second expansion valve 9 into a fully closed state when a refrigerant leak is detected by the indoor refrigerant leak sensor 41.

According to the air conditioner 100 according to the first embodiment, it is possible to prevent the refrigerant from flowing into the main circuit 31 provided indoors, and the refrigerant can be stored in the outdoor heat exchanger 7 and the liquid reservoir 8. It is possible to suppress leakage of refrigerant to.

Furthermore, the air conditioner 100 according to the first embodiment includes an outdoor refrigerant leak sensor 42 that is provided outside the air-conditioned space and detects refrigerant leakage, and the control device 50 controls the refrigerant leakage sensor 42 in the outdoor refrigerant leakage sensor 42. When leakage is detected, the second on-off valve 6 is closed.

Furthermore, in the air conditioner 100 according to the first embodiment, the control device 50 brings the first expansion valve 4 into a fully closed state when refrigerant leakage is detected by the outdoor refrigerant leakage sensor 42.

According to the air conditioner 100 according to the first embodiment, it is possible to block the flow of refrigerant to the outdoors, and the outdoor refrigerant can be stored in the indoor heat exchanger 5, thereby preventing leakage of the refrigerant outdoors. Can be suppressed.

Furthermore, in the air conditioner 100 according to the first embodiment, a non-azeotropic mixed refrigerant is used as the refrigerant that circulates in the refrigerant circuit 30.

Further, in the air conditioner 100 according to the first embodiment, the evaporator and the reheater 3 are such that air that has passed through the refrigerant inlet side of the evaporator passes through the refrigerant outlet side of the reheater 3, In addition, the air passing through the refrigerant outlet side of the evaporator is arranged so as to pass through the refrigerant inlet side of the reheater 3.

Furthermore, in the air conditioner 100 according to the first embodiment, both the evaporator and the reheater 3 are provided so that the refrigerant flows from the top to the bottom.

According to the air conditioner 100 according to the first embodiment, by using a non-azeotropic mixed refrigerant as the refrigerant to be circulated through the refrigerant circuit 30, the temperature at the inlet side of the refrigerant in the indoor heat exchanger 5 is lower than that at the outlet of the refrigerant. lower than the temperature on the side. Further, in the reheater 3, the temperature on the refrigerant inlet side is higher than the temperature on the refrigerant outlet side. Then, the air that has passed through the refrigerant inlet side of the indoor heat exchanger 5 passes through the refrigerant outlet side of the reheater 3, and the indoor heat exchanger 5 and the reheater 3 The reheater 3 is arranged so that the air that has passed through the refrigerant outlet side of the reheater 5 passes through the refrigerant inlet side of the reheater 3. For example, a portion of the indoor heat exchanger 5 where the refrigerant temperature is relatively low is opposed to a portion of the reheater 3 where the refrigerant temperature is relatively high, and the refrigerant temperature of the indoor heat exchanger 5 is relatively high. and a portion of the reheater 3 where the refrigerant temperature is relatively low are arranged so as to face each other. That is, the indoor heat exchanger 5 and the reheater 3 are both provided so that the refrigerant flows from the top to the bottom. By arranging the indoor heat exchanger 5 and the reheater 3 in this way, variations in the blowout temperature, which is the temperature of the air blown out from the indoor unit 70 into the air-conditioned space, and unevenness in humidity caused by the dispersion in the blowout temperature are reduced. and can be reduced. Therefore, variations in the humidity of the air blown out from the indoor unit 70 into the air-conditioned space can be suppressed, and the state of the indoor air can be stabilized.

Embodiment 2.
Embodiment 2 will be described below, but the description of parts that overlap with Embodiment 1 will be omitted, and the same or corresponding parts as in Embodiment 1 will be given the same reference numerals.

FIG. 11 is an overall configuration diagram of an air conditioner 200 according to the second embodiment. The air conditioner 200 according to the second embodiment is different from the air conditioner 100 according to the first embodiment in a part of the configuration of the refrigerant circuit 30.

As shown in FIG. 11, the refrigerant circuit 30 according to the second embodiment is different from the first embodiment in that the liquid reservoir 8 is not provided and an accumulator 18 is provided instead. The other configurations are the same as in the first embodiment. The air conditioner 200 can store refrigerant in the accumulator 18 provided between the compressor 1 and the indoor heat exchanger 5 during a transient liquid back-up, and can further reduce the risk of damage to the compressor 1. do.

In the second embodiment, the reheater 3 and the outdoor heat exchanger 7 are controlled by implementing the operation switching control described in the first embodiment, the refrigerant distribution control during the cooling operation, or the refrigerant distribution during the dehumidifying operation. It is possible to operate with the optimum amount of refrigerant in each case. Therefore, the capacity of the air conditioner 200 can be maintained appropriately, and surplus refrigerant generated transiently can be stored in the inexpensive accumulator 18. In other words, even if the refrigerant returns to the compressor 1 due to liquid backing, the action of the accumulator 18 can suppress liquid compression in the compressor 1, providing a highly reliable air conditioner 200. can do. The degree of subcooling of the reheater 3 is determined from the high pressure obtained from the pressure sensor 62 and the reheater outlet temperature obtained from the refrigerant temperature sensor 67. The degree of supercooling of the reheater 3 can be determined by converting the high pressure into saturation to determine the condensation temperature, and subtracting the reheater outlet temperature from the condensation temperature. Further, the degree of subcooling of the outdoor heat exchanger 7 is determined from the high pressure obtained from the pressure sensor 64 and the outdoor heat exchanger outlet temperature obtained from the refrigerant temperature sensor 69. The degree of supercooling at the outlet of the outdoor heat exchanger can be determined by converting the high pressure into saturation to determine the condensation temperature, and subtracting the outdoor heat exchanger outlet temperature from the condensation temperature. Note that when determining the degree of subcooling of the outdoor heat exchanger 7, the pressure acquired from the pressure sensor 62 may be used as the high pressure.

The control of each on-off valve and each expansion valve when refrigerant leaks indoors or outdoors is the same as in the first embodiment described above.

As described above, the air conditioner 200 of Embodiment 2 can also suppress a decrease in dehumidification ability and efficiently perform dehumidification operation. By the way, as in the first embodiment, in the refrigerant circuit 30 including the liquid reservoir 8, it is necessary to operate the second expansion valve 9 to ensure the degree of superheating in order to protect against liquid back. . Therefore, in order to store the surplus refrigerant, an expensive high-pressure container such as the liquid reservoir 8 with a large capacity is required.

In this regard, in the air conditioner 200 according to the second embodiment, even if the refrigerant returns toward the compressor 1 due to the liquid back, the action of the accumulator 18 will cause the liquid in the compressor 1 to flow even if there is no liquid reservoir. Since compression can be suppressed, the reliability of the air conditioner 200 can be improved.

The air conditioner 200 then uses the accumulator 18 to separate the non-azeotropic mixed refrigerant into gas and liquid, stores the high boiling point refrigerant in the accumulator 18, and uses the low boiling point refrigerant during defrosting operation. Increase heat capacity. In other words, during the defrosting operation, the air conditioner 200 stores the high boiling point refrigerant included in the non-azeotropic mixed refrigerant in the accumulator 18 and transfers the low boiling point refrigerant included in the non-azeotropic refrigerant mixture to the refrigerant circuit 30. Circulate. Therefore, the defrosting time can be shortened. Other effects and the like are the same as in the first embodiment.

Note that the operations of each on-off valve and each expansion valve at the time of refrigerant leak illustrated in FIG. 10 can also be applied to the configuration of Embodiment 2.

Each of the embodiments described above is a preferred specific example of the

air conditioner

100, 200, and the technical scope of the present disclosure is not limited to these aspects. For example, the

air conditioners

100, 200 may not have the function of performing cooling operation and defrosting operation, and in this case, the first on-off valve 2 is not required. Therefore, in the main circuit 31, the compressor 1, the reheater 3, the first expansion valve 4, and the indoor heat exchanger 5 are sequentially connected by the main pipe 21. Further, in the first embodiment, an example in which the liquid reservoir 8 is provided in the refrigerant circuit 30 is shown, but the refrigerant circuit 30 according to the first embodiment does not need to have the liquid reservoir 8. good. Furthermore, in each of the above embodiments, the main circuit 31 is arranged in an air-conditioned space, but the main circuit 31 is not limited to this. 5 may be placed in an air-conditioned space. In addition, the refrigerant circuit 30 according to the first embodiment does not need to include the bypass circuit 33. However, unless the bypass circuit 33 is provided in the refrigerant circuit 30, the defrosting operation in the flow path as in the first embodiment is not possible.

Although FIG. 1 and FIG. 11 show an example in which the indoor refrigerant leak sensor 41 is provided inside the indoor unit 70, the indoor refrigerant leak sensor 41 is provided inside the air-conditioned space, and is not limited to this. It may be provided outside of 70. Similarly, although FIGS. 1 and 11 show an example in which the outdoor refrigerant leak sensor 42 is provided inside the outdoor unit 80, the outdoor refrigerant leak sensor 42 is not limited to this. It may be provided externally.

Although FIGS. 1 and 11 show an example in which the control device 50 is provided inside the indoor unit 70, the control device 50 is not limited to this, and may be provided inside the outdoor unit 80. Further, the outdoor unit 80 is provided with an outdoor control device that controls the operation of each actuator of the outdoor unit 80 such as the outdoor blower 12, and the control device 50 and the outdoor control device cooperate to control the

air conditioners

100 and 200. You may.

As described above, in the air conditioner 200 according to the second embodiment, the refrigerant circuit 30 includes the accumulator 18 provided between the compressor 1 and the evaporator.

According to the air conditioner 200 according to the second embodiment, even if the refrigerant returns toward the compressor 1 due to the liquid back, the action of the accumulator 18 can suppress liquid compression in the compressor 1. Therefore, the reliability of the air conditioner 200 can be improved.

1 Compressor, 1a Compressor motor, 2 First on-off valve, 3 Reheater, 4 First expansion valve, 5 Indoor heat exchanger, 6 Second on-off valve, 7 Outdoor heat exchanger, 8 Liquid reservoir, 9 No. 2 expansion valve, 10 third on-off valve, 11 indoor blower, 11a fan motor, 12 outdoor blower, 12a fan motor, 18 accumulator, 20 refrigerant piping, 21 main piping, 22 cooling piping, 23 bypass piping, 30 refrigerant circuit, 31 Main circuit, 32 Cooling circuit, 33 Bypass circuit, 41 Indoor refrigerant leak sensor, 42 Outdoor refrigerant leak sensor, 45 Abnormality alarm, 50 Control device, 51 Arithmetic processing unit, 51a Setting processing unit, 51b Operation control unit, 51c Surplus refrigerant Detection unit, 51d Leakage processing unit, 52 Storage unit, 61 Pressure sensor, 62 Pressure sensor, 63 Pressure sensor, 64 Pressure sensor, 65 Refrigerant temperature sensor, 66 Refrigerant temperature sensor, 67 Refrigerant temperature sensor, 68 Refrigerant temperature sensor, 69 Refrigerant Temperature sensor, 70 indoor unit, 80 outdoor unit, 91 air temperature sensor, 92 air temperature sensor, 100 air conditioner, 200 air conditioner.

Claims

A main circuit in which a compressor, a first on-off valve, a reheater, a first expansion valve, and an evaporator are sequentially connected by a main pipe, and a main circuit that connects the first expansion valve between the compressor and the first on-off valve. a cooling circuit in which a second on-off valve, a condenser, and a second expansion valve are sequentially connected by cooling piping that connects between the reheater and the first expansion valve from the discharge side of the compressor; A refrigerant circuit in which refrigerant circulates, including a bypass pipe that connects to an expansion valve and a third on-off valve that opens and closes the bypass pipe;
a control device that controls the refrigerant circuit;
The reheater and the evaporator are arranged in an air-conditioned space,
The condenser is located outside the air-conditioned space,
The control device includes:
Before switching the operation to a cooling operation that cools the air in the air-conditioned space or a dehumidification operation that dehumidifies the air in the air-conditioned space,
The first on-off valve and the second on-off valve are opened, and the third on-off valve is closed,
Implementing operation switching control in which the first expansion valve is used to control the degree of superheating on the suction side of the compressor, and the second expansion valve is used to control the degree of subcooling of the condenser. Device.
The control device includes:
During the operation switching control,
When the degree of supercooling of the condenser and the degree of superheating of the suction side of the compressor reach preset values, or when a preset time has elapsed, the operation is switched to the cooling operation or the dehumidifying operation. Item 1. The air conditioner according to item 1.
The control device includes:
During the cooling operation,
Based on the degree of subcooling of the condenser, the condensing temperature of the condenser and the internal liquid temperature, which is the temperature of the refrigerant flowing through the reheater, or the condensing temperature of the condenser or the internal liquid temperature, The air conditioner according to claim 1 or 2, which performs refrigerant distribution control.
The control device includes:
During the cooling operation,
When the degree of supercooling of the condenser is below a preset value,
The condensing temperature of the condenser is lower than a value at which high-pressure protection is implemented, which is control to lower the frequency of the compressor or stop the compressor, and the internal liquid temperature is lower than the value at which high pressure protection is implemented, which is control to lower the frequency of the compressor or stop the compressor, and the internal liquid temperature If the temperature is higher than
The air conditioner according to claim 3, wherein refrigerant distribution control is performed to control the first expansion valve so that the degree of subcooling of the condenser becomes a preset value.
The control device includes:
During the cooling operation,
When the degree of supercooling of the condenser is below a preset value,
The condensing temperature of the condenser is not lower than a value at which high pressure protection is implemented, which is control to lower the frequency of the compressor or stop the compressor, or the internal liquid temperature is If not higher than the evaporation temperature,
The first on-off valve and the second on-off valve are opened, and the third on-off valve is closed,
Controlling the degree of supercooling of the reheater using the first expansion valve,
The air conditioner according to claim 3 or 4, wherein refrigerant distribution control is performed by controlling the degree of superheat on the suction side of the compressor using the second expansion valve.
The control device includes:
During the cooling operation,
When the degree of supercooling of the condenser is greater than a preset value,
When the condensation temperature of the condenser is higher than the internal liquid temperature,
Any one of claims 3 to 5, wherein refrigerant distribution control is performed by opening the first on-off valve and controlling the first expansion valve so that the degree of subcooling of the condenser becomes a preset value. The air conditioner according to item 1.
The control device includes:
During the cooling operation,
When the degree of supercooling of the condenser is greater than a preset value,
When the condensing temperature of the condenser is not higher than the internal liquid temperature,
The first on-off valve and the second on-off valve are opened, and the third on-off valve is closed,
controlling the degree of superheat on the suction side of the compressor using the first expansion valve;
The air conditioner according to any one of claims 3 to 6, wherein refrigerant distribution control is performed by controlling the degree of subcooling of the condenser using the second expansion valve.
The control device includes:
During the dehumidification operation,
Based on the degree of subcooling of the reheater, the condensing temperature of the reheater and the external liquid temperature, which is the temperature of the refrigerant flowing through the condenser, or the condensing temperature of the reheater or the external liquid temperature. The air conditioner according to any one of claims 1 to 7, wherein the air conditioner performs refrigerant distribution control.
The control device includes:
During the dehumidification operation,
When the degree of subcooling of the reheater is below a preset value,
The condensing temperature of the reheater is lower than the value at which high-pressure protection is implemented, which is control to lower the frequency of the compressor or stop the compressor, and the external liquid temperature is lower than the value of the high pressure protection of the evaporator. If higher than the evaporation temperature,
The air conditioner according to claim 8, wherein refrigerant distribution control is performed to control the second expansion valve so that the degree of subcooling of the reheater becomes a preset value.
The control device includes:
During the dehumidification operation,
When the degree of subcooling of the reheater is below a preset value,
The condensing temperature of the reheater is not lower than a value at which high pressure protection is implemented, which is control to lower the frequency of the compressor or stop the compressor, or the external liquid temperature is if not higher than the evaporation temperature of
The first on-off valve and the second on-off valve are opened, and the third on-off valve is closed,
controlling the degree of superheat on the suction side of the compressor using the first expansion valve;
The air conditioner according to claim 8 or 9, wherein refrigerant distribution control is performed in which the degree of subcooling of the condenser is controlled using the second expansion valve.
The control device includes:
During the dehumidification operation,
When the degree of subcooling of the reheater is greater than a preset value,
When the condensing temperature of the reheater is higher than the external liquid temperature,
Any one of claims 8 to 10, wherein refrigerant distribution control is performed by opening the second on-off valve and controlling the second expansion valve so that the degree of subcooling of the reheater becomes a preset value. The air conditioner according to item 1.
The control device includes:
During the dehumidification operation,
When the degree of subcooling of the reheater is greater than a preset value,
When the condensing temperature of the reheater is not higher than the external liquid temperature,
The first on-off valve and the second on-off valve are opened, and the third on-off valve is closed,
Controlling the degree of supercooling of the reheater using the first expansion valve,
The air conditioner according to any one of claims 8 to 11, wherein refrigerant distribution control is performed in which the second expansion valve is used to control the degree of superheat on the suction side of the compressor.