CN113227677B - Air conditioner - Google Patents

Abstract

The invention provides an air conditioning apparatus having a refrigerant circuit through 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 reheater, a 1 st expansion valve, and an evaporator are sequentially connected by a main pipe, and a cooling circuit in which a cooling opening/closing valve, a condenser, and a 2 nd expansion valve are connected by a cooling pipe connecting between the compressor and the reheater and between the 1 st expansion valve and the evaporator. The reheater and the evaporator are disposed in the conditioned space, and the condenser is disposed outside the conditioned space. When the degree of supercooling by the reheater is outside the appropriate range of the refrigerant amount during the dehumidification operation, the control device controls the cooling on-off valve or the 2 nd expansion valve based on the result of the determination using the outside air temperature. Further, when the degree of supercooling by the condenser is out of the appropriate range of the refrigerant amount during the cooling operation, the control device controls the reheat opening/closing valve or the 1 st expansion valve of the main circuit based on the result of the determination using the temperature of the internal liquid.

Description

Air conditioner

Technical Field

The present invention relates to an air conditioning apparatus having a function of performing a reheat dehumidification operation.

Background

Conventionally, an air-conditioning apparatus having a reheater and an evaporator provided indoors and a condenser provided outdoors is known (for example, see patent document 1). The air-conditioning apparatus of patent document 1 controls the dehumidification capability of the evaporator by adjusting the amount of refrigerant flowing to the reheater and the amount of refrigerant flowing to the condenser.

Patent document 1: japanese patent laid-open publication No. 2011-133171

However, in the air-conditioning apparatus of patent document 1, the refrigerant distributed in each heat exchanger may become uneven due to a difference between the indoor temperature and the outside air temperature, and liquid returning may occur during the cooling operation or the reheat dehumidification operation, resulting in the overheat operation. If liquid return occurs, liquid compression in the compressor occurs, and the compressor may malfunction. In addition, in the case of the overheat operation, since the amount of refrigerant circulating among the compressor, the reheater, the expansion valve, and the evaporator is insufficient, the capacity is reduced, and the discharge temperature is increased, so that the operation cannot be performed efficiently.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide an air-conditioning apparatus in which unevenness in refrigerant distribution in a refrigerant circuit is suppressed, and an operation efficiency is improved.

An air conditioning device according to the present invention includes: a refrigerant circuit including a main circuit in which a compressor, a reheater, a 1 st expansion valve, and an evaporator are sequentially connected by a main pipe, and a cooling circuit in which a cooling opening/closing valve, a condenser, and a 2 nd expansion valve are connected by a cooling pipe, the refrigerant circuit circulating a refrigerant, the cooling pipe connecting between the compressor and the reheater and between the 1 st expansion valve and the evaporator; and a control device for controlling the refrigerant circuit, wherein the reheater and the evaporator are arranged in the air-conditioned space, the condenser is arranged outside the air-conditioned space, and when the supercooling degree by the reheater is out of the proper range of the refrigerant amount indicating that the refrigerant amount distributed in the reheater is proper during the dehumidification operation for dehumidifying the air in the air-conditioned space, the control device controls the cooling on-off valve or the 2 nd expansion valve according to the result of the determination using the external liquid temperature, which is the temperature of the refrigerant flowing out of the condenser.

According to the present invention, when the degree of supercooling by the reheater during the dehumidification operation is outside the appropriate range of the refrigerant amount, the control device controls the cooling on-off valve or the 2 nd expansion valve based on the result of the determination using the outside air temperature. Therefore, since the amount of refrigerant in the reheater can be adjusted according to the outside-liquid temperature, the unevenness of refrigerant distribution in the refrigerant circuit can be suppressed, and the operating efficiency can be improved.

Drawings

Fig. 1 is an overall configuration diagram of an air-conditioning apparatus according to embodiment 1 of the present invention.

Fig. 2 is a block diagram schematically showing a functional configuration of the control device of fig. 1.

Fig. 3 is an explanatory diagram showing a state of the refrigerant circuit in the dehumidification operation of the air-conditioning apparatus of fig. 1.

Fig. 4 is an explanatory diagram showing a state of the refrigerant circuit in the air-conditioning apparatus of fig. 1 during the intermediate operation.

Fig. 5 is an explanatory diagram showing a state of the refrigerant circuit in the cooling operation of the air-conditioning apparatus of fig. 1.

Fig. 6 is an explanatory diagram showing a state of the refrigerant circuit in the defrosting operation of the air-conditioning apparatus of fig. 1.

Fig. 7 is an explanatory diagram showing timing at which the control device of fig. 1 performs operation switching control.

Fig. 8 is a flowchart showing an operation related to the operation switching control of the control device of fig. 1.

Fig. 9 is a flowchart illustrating the refrigerant distribution control during the cooling operation according to the control device of fig. 1.

Fig. 10 is a flowchart illustrating refrigerant distribution control during the dehumidification operation according to the control device of fig. 1.

Fig. 11 is an explanatory diagram illustrating a specific configuration of the indoor heat exchanger according to embodiment 2 of the present invention.

Fig. 12 is an explanatory view illustrating a mollier diagram of a zeotropic refrigerant mixture.

Fig. 13 is a mollier chart showing a specific example of the temperature gradient of the zeotropic refrigerant mixture.

Fig. 14 is an explanatory diagram showing an example of arrangement of the evaporator and the reheater in the air-conditioning apparatus according to embodiment 2 of the present invention.

Fig. 15 is a table showing states of each opening/closing valve and each expansion valve when refrigerant leaks in the air-conditioning apparatus according to embodiment 2 of the present invention.

Fig. 16 is an overall configuration diagram of an air-conditioning apparatus according to embodiment 3 of the present invention.

Detailed Description

Embodiment 1.

Fig. 1 is an overall configuration diagram of an air-conditioning apparatus according to embodiment 1 of the present invention. The air conditioning apparatus 100 is used to adjust the temperature and humidity of air in an air-conditioned space such as a room, and has a function of performing a reheat dehumidification operation. As shown in fig. 1, the air-conditioning apparatus 100 includes an indoor unit 70 provided in an air-conditioned space and an outdoor unit 80 provided outside the air-conditioned space. The indoor unit 70 and the outdoor unit 80 are connected by a refrigerant pipe 20. Hereinafter, the inside of the air-conditioned space is also referred to as the inside of the room, and the outside of the air-conditioned space is also referred to as the outside of the room.

The indoor unit 70 is, for example, a floor dehumidifier placed on a floor of an air-conditioned space, a ceiling dehumidifier or a ceiling dehumidifier installed on a ceiling, or the like. The indoor unit 70 houses a compressor 1, a reheat opening/closing valve 2, a reheater 3, a 1 st expansion valve 4, an indoor heat exchanger 5, a cooling opening/closing valve 6, a 2 nd expansion valve 9, and a defrost opening/closing valve 10. The outdoor unit 80 is installed outdoors or in a machine room. The outdoor unit 80 houses the outdoor heat exchanger 7 and the liquid reservoir 8. That is, the air-conditioning apparatus 100 includes a refrigerant circuit 30, and the refrigerant circuit 30 is formed by connecting the compressor 1, the reheat opening/closing valve 2, the reheater 3, the 1 st expansion valve 4, the indoor heat exchanger 5, the cooling opening/closing valve 6, the outdoor heat exchanger 7, the liquid reservoir 8, the 2 nd expansion valve 9, and the defrost opening/closing valve 10 by the refrigerant pipe 20, and circulates the refrigerant.

As the refrigerant circulating through the refrigerant circuit 30, a single mixed refrigerant, a pseudo single mixed refrigerant, a non-azeotropic mixed refrigerant, or the like can be used. As the zeotropic refrigerant mixture, for example, R32, R125, R134a, R1234yf and CO can be used ₂ The mixed refrigerant of (1). The non-azeotropic mixed refrigerant comprises 49-55 wt% of R32, 16-22 wt% of R125, 7-13 wt% of R134a, 6-12 wt% of R1234yf, CO ₂ The composition (B) is a composition ratio of 7 to 13wt% to 100wt%. Further, as the non-azeotropic refrigerant mixture, a non-azeotropic refrigerant mixture having a composition other than the above-described one, that is, R448A, R a or R407F, may be used.

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 in which the compressor 1, the reheat opening/closing valve 2, the reheater 3, the 1 st expansion valve 4, and the indoor heat exchanger 5 are connected in this order in a loop shape. That is, the refrigerant circuit 30 includes a main circuit 31 in which the compressor 1, the reheat opening/closing valve 2, the reheater 3, the 1 st expansion valve 4, and the indoor heat exchanger 5 are connected by a main pipe 21.

The cooling pipe 22 is a pipe connecting the space between the compressor 1 and the reheater 3 to the space between the 1 st expansion valve 4 and the indoor heat exchanger 5. More specifically, the cooling pipe 22 is a pipe that connects the main pipe 21 between the compressor 1 and the reheat opening/closing valve 2 and the main pipe 21 between the 1 st expansion valve 4 and the indoor heat exchanger 5, and connects the cooling opening/closing valve 6, the outdoor heat exchanger 7, the liquid storage unit 8, and the 2 nd expansion valve 9. That is, the refrigerant circuit 30 includes a cooling circuit 32 that is an open circuit formed by connecting the cooling on-off valve 6, the outdoor heat exchanger 7, the liquid reservoir 8, and the 2 nd expansion valve 9 via the cooling pipe 22. Here, a connection portion between the main pipe 21 and the cooling pipe 22 between the compressor 1 and the reheat on-off valve 2 is referred to as a 1 st connection portion M. The connection portion between the 1 st expansion valve 4 and the indoor heat exchanger 5 and the cooling pipe 22 is referred to as a 2 nd connection portion N.

The bypass pipe 23 is a pipe connecting the exhaust side of the compressor 1 to a position between the reheater 3 and the 1 st expansion valve 4. In embodiment 1, the discharge side of the compressor 1 is between the compressor 1 and the 1 st connection unit M. More specifically, the bypass pipe 23 is a pipe connecting the main pipe 21 between the compressor 1 and the 1 st connection portion M and the main pipe 21 between the reheater 3 and the 1 st expansion valve 4, and is provided with a defrost opening/closing valve 10 for opening and closing the bypass pipe 23. That is, the refrigerant circuit 30 includes a bypass circuit 33, which is an open circuit in which the defrosting on-off valve 10 is provided in the bypass pipe 23. Here, as shown in fig. 1, the reheater 3 and the 1 st expansion valve 4 are connected in parallel to the outdoor heat exchanger 7 and the 2 nd expansion valve 9.

The compressor 1 sucks and compresses a refrigerant, and discharges the refrigerant in a high-temperature and high-pressure gas state. The compressor 1 is a compressor whose rotation speed is controlled by, for example, an inverter circuit or the like, and which can adjust the discharge amount of refrigerant. However, the compressor 1 may be a constant speed compressor that operates at a constant rotational speed.

The reheater 3, the indoor heat exchanger 5, and the outdoor heat exchanger 7 are fin-tube heat exchangers each formed of, for example, a pipe through which the refrigerant flows and a fin attached to the pipe. The reheater 3 condenses the refrigerant compressed by the compressor 1 by heat exchange with air. In the air-conditioning apparatus 100, the indoor heat exchanger 5 and the reheater 3 are provided on a common air path.

The indoor heat exchanger 5 is an air heat exchanger functioning as an evaporator (cooler) for evaporating the refrigerant. That is, the indoor heat exchanger 5 evaporates the refrigerant by exchanging heat between the refrigerant expanded by at least one of the 1 st expansion valve 4 and the 2 nd expansion valve 9 and the air. The outdoor heat exchanger 7 is an air heat exchanger that functions as a condenser for condensing the 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 1 st expansion valve 4 is composed of, for example, an electronic expansion valve, and is disposed downstream of the reheater 3. The 1 st expansion valve 4 expands the refrigerant condensed by the reheater 3. The 2 nd expansion valve 9 is composed of, for example, an electronic expansion valve, and is disposed downstream of the outdoor heat exchanger 7. The 2 nd expansion valve 9 expands the refrigerant condensed by the outdoor heat exchanger 7.

The reheat on-off valve 2, the cooling on-off valve 6, and the defrost on-off valve 10 are, for example, solenoid valves having an open state and a closed state, and allow the refrigerant to pass therethrough in the open state. The reheat opening/closing valve 2 blocks the refrigerant that is going to flow to the reheater 3 through the 1 st connection portion M in the closed state. The cooling on-off valve 6 blocks the refrigerant that is going to flow to the outdoor heat exchanger 7 through the 1 st connecting portion M when in a closed state. The defrost on-off valve 10 blocks the refrigerant that is going to flow to the bypass pipe 23 when in a closed state. The receiver 8 is a member for storing excess refrigerant.

The indoor unit 70 is provided with an indoor fan 11 that sends air to the indoor heat exchanger 5 and the reheater 3. The outdoor unit 80 is provided with an outdoor fan 12, and the outdoor fan 12 is attached to the outdoor heat exchanger 7 and blows air to the outdoor heat exchanger 7. In embodiment 1, the indoor fan 11 and the outdoor fan 12 are fans whose rotation speeds are controlled by, for example, an inverter circuit or the like, and can adjust the air blowing amounts.

The indoor unit 70 is provided with an indoor refrigerant leakage 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 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 a low-pressure, which is the pressure of the refrigerant sucked into the compressor 1. The pressure sensor 62 is provided on the discharge side of the compressor 1, and measures a 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 of 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 of the outdoor heat exchanger 7.

The refrigerant temperature sensors 65 to 69 are, for example, thermistors. The refrigerant temperature sensor 65 is provided on the suction side of the compressor 1, and measures a 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 a discharge temperature, which is the temperature of the refrigerant discharged from the compressor 1. The refrigerant temperature sensor 67 is provided on the outlet side of the reheater 3, and measures a reheater outlet temperature (internal liquid temperature) that is the temperature of the refrigerant flowing out of the reheater 3. The refrigerant temperature sensor 68 is provided on the outlet side of the indoor heat exchanger 5, and measures the temperature of the refrigerant flowing out of the indoor heat exchanger 5 (evaporator outlet temperature). The refrigerant temperature sensor 69 is provided on the outlet side of the outdoor heat exchanger 7, and measures a condenser outlet temperature (outside liquid temperature), which is the temperature of the refrigerant flowing out of the outdoor heat exchanger 7.

The air temperature sensors 91 and 92 are, for example, thermistors. The air temperature sensor 91 is provided at the inlet 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 of the outdoor or machine room, etc., as the outside air temperature.

The indoor refrigerant leakage sensor 41 is provided in the air-conditioned space, and detects leakage of refrigerant. The outdoor refrigerant leakage sensor 42 is provided outside the air-conditioned space and detects leakage of the refrigerant. The indoor refrigerant leakage sensor 41 and the outdoor refrigerant leakage sensor 42 output leakage signals indicating the occurrence of refrigerant leakage to the control device 50 when refrigerant leakage is detected. Each pressure sensor outputs data of the measured pressure to the control device 50. Each temperature sensor outputs data of the measured temperature to the control device 50. That is, the refrigerant leakage sensors, the pressure sensors, and the temperature sensors are electrically or optically connected to the control device 50.

The indoor unit 70 is provided with an abnormality annunciator 45 including at least 1 of a speaker and a light emitter. As the light emitting body, an LED (light emitting diode) or the like can be used. The abnormality reporter 45 reports the occurrence of an abnormality by outputting a sound, voice, light, or the like in accordance with an instruction from the control device 50.

The control device 50 is used to control the refrigerant circuit 30. That is, the controller 50 obtains the outputs of the pressure sensors and the temperature sensors to control various actuators such as the compressor 1, the reheat opening/closing valve 2, the 1 st expansion valve 4, the cooling opening/closing valve 6, the 2 nd expansion valve 9, and the defrost opening/closing valve 10. When an abnormality occurs, the control device 50 causes the abnormality reporter 45 to report the occurrence of the abnormality. When an abnormality in refrigerant leakage is detected by each refrigerant leakage sensor, the control device 50 of embodiment 1 causes the abnormality annunciator 45 to output a sound, voice, light, or the like.

The controller 50 is configured to include, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The RAM is a volatile storage medium that stores various data. The ROM is a nonvolatile storage medium that stores an operation program and the like for causing the control device 50 to execute operation control according to each operation mode described later. The controller 50 controls the compressor 1, the reheat opening/closing valve 2, the 1 st expansion valve 4, the cooling opening/closing valve 6, the 2 nd expansion valve 9, the defrost opening/closing valve 10, and the like as appropriate according to the operation program in the ROM, and performs the air conditioning according to each operation mode. That is, the control device 50 can be configured by an arithmetic device such as a CPU and an operation program that realizes various functions described below in cooperation with such an arithmetic device.

Here, the flow of air in the indoor unit 70 will be briefly described. When the indoor fan 11 is operated, air is taken into the indoor unit 70. The air taken into the indoor unit 70 passes through the indoor heat exchanger 5 functioning as an evaporator, and the absolute humidity thereof is reduced. That is, since moisture in the air is condensed in the indoor heat exchanger 5 by the air containing moisture passing through the indoor heat exchanger 5, the absolute humidity of the air is lowered. The air having a decreased absolute humidity and a decreased temperature due to passing through the indoor heat exchanger 5 becomes cold air having a high relative humidity. The air having passed through the indoor heat exchanger 5 is reheated by passing through the reheater 3, and the relative humidity is lowered. Then, the air having a reduced relative humidity by the reheater 3 is blown into the room. As described above, since the air taken into the indoor unit 70 is blown out into the room with the relative humidity reduced, the indoor relative humidity is reduced. This is the flow of air in the indoor unit 70 during the dehumidification operation or the intermediate operation described later.

Fig. 2 is a block diagram schematically showing a functional configuration of the control device of fig. 1. The control device 50 includes an arithmetic processing unit 51 and a storage unit 52. The arithmetic processing unit 51 includes a setting processing unit 51a, an operation control unit 51b, an excess refrigerant detection unit 51c, and a leakage processing unit 51d. The setting processing unit 51a receives an operation signal indicating the operation and setting contents of the user from a controller device (not shown) or the like for operating the air-conditioning apparatus 100. The setting processor 51a sets the operation mode, the target temperature, the target humidity, and the like based on the operation signal.

The excess refrigerant detector 51c detects the occurrence of excess refrigerant by any of the following methods, and when the occurrence of excess refrigerant is detected, outputs a detection signal to the operation controller 51 b. For example, the excess refrigerant detector 51c may be configured to obtain the degree of subcooling and determine whether the obtained degree of subcooling is larger than a subcooling threshold value. This determination utilizes the fact that the degree of subcooling becomes large when excess refrigerant is generated. That is, when the obtained degree of subcooling is larger than the subcooling threshold value, the excess refrigerant detecting unit 51c outputs a detection signal to the operation control unit 51 b.

In addition, the detection of the excess refrigerant may use a case where the discharge temperature of the refrigerant becomes low when the excess refrigerant is generated. That is, the excess refrigerant detector 51c may acquire the discharge temperature from the refrigerant temperature sensor 66 and determine whether the acquired discharge temperature is less than the discharge threshold. The excess refrigerant detector 51c may output a detection signal to the operation controller 51b when the discharge temperature is lower than the discharge threshold.

The detection of the excess refrigerant may be performed by using a case where the high-pressure rises when the excess refrigerant is generated. That is, the excess refrigerant detector 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 excess refrigerant detector 51c may output a detection signal to the operation controller 51b when the high-pressure is greater than the high-pressure threshold.

In addition, the detection of the excess refrigerant may be performed by using a case where the low-pressure rises when the excess refrigerant is generated. That is, the excess refrigerant detector 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 excess refrigerant detector 51c may output a detection signal to the operation controller 51b when the low-pressure is greater than the low-pressure threshold.

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

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 annunciator 45 to output a sound, a voice, a light, or the like. The leakage processing unit 51d may cause the abnormality annunciator 45 to output different sounds, voices, lights, or the like, when the leakage signal is acquired from the indoor refrigerant leakage sensor 41 and when the leakage signal is acquired from the outdoor refrigerant leakage sensor 42.

The operation control unit 51b periodically acquires measurement data from each pressure sensor and each temperature sensor. The operation control unit 51b controls the operation of each actuator of the air-conditioning apparatus 100 using the acquired measurement data according to the setting content of the setting processing unit 51 a. 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 fan 11, and the fan motor 12a of the outdoor fan 12.

When the operation mode is set to the dehumidification operation mode by a user operation or default setting, the operation control unit 51b causes the air-conditioning apparatus 100 to perform a dehumidification operation for dehumidifying 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-conditioning apparatus 100 to perform the intermediate operation. When the operation mode is set to the cooling operation mode, the operation control unit 51b causes the air-conditioning apparatus 100 to perform a cooling operation for cooling air in the air-conditioned space. When the operation mode is set to the defrosting operation mode, the operation controller 51b causes the air-conditioning apparatus 100 to perform a defrosting operation for melting frost adhering to the indoor heat exchanger 5.

For example, the operation controller 51b closes the cooling on-off valve 6 during the dehumidification operation. The operation controller 51b may set the 2 nd expansion valve 9 in a fully closed state during the dehumidification operation. This prevents the refrigerant from flowing into the main circuit 31 from the cooling circuit 32. Further, the operation control unit 51b closes the reheat opening/closing valve 2 during the cooling operation. The operation controller 51b may set the 1 st expansion valve 4 in a fully closed state during the cooling operation. This prevents the refrigerant accumulated in the reheater 3 and the like from flowing into the indoor heat exchanger 5.

The operation control unit 51b has a function of performing operation switching control for equalizing the refrigerant in the refrigerant circuit 30 at the time of starting the compressor 1 and at the time of switching the operation mode. In the operation in each operation mode, the operation controller 51b performs refrigerant distribution control for optimizing the refrigerant distribution in the refrigerant circuit 30 based on the state value indicating the state of the refrigerant circuit 30. The specific contents of the operation switching control and the refrigerant distribution control will be described later.

In addition, when the excess refrigerant is generated, the operation control unit 51b causes the air-conditioning apparatus 100 to perform a refrigerant amount adjustment operation, which will be described later. That is, when the detection signal is output from the excess refrigerant detector 51c, the operation controller 51b performs refrigerant amount adjustment control for accumulating the excess refrigerant in the receiver 8 while maintaining the performance of the reheater 3.

When the refrigerant leakage is detected by the indoor refrigerant leakage sensor 41, that is, when the indoor leakage signal is output from the leakage processing unit 51d, the operation control unit 51b closes the reheat opening/closing valve 2 and completely closes the 2 nd expansion valve 9. Accordingly, the refrigerant flowing from the 1 st connection unit M to the reheater 3 can be cut off, and the refrigerant in the room can be stored in the outdoor heat exchanger 7 and the receiver 8, so that leakage of the refrigerant into the room can be suppressed. When the indoor refrigerant leakage sensor 41 detects the leakage of the refrigerant, the operation control unit 51b may set the 1 st expansion valve 4 in the fully closed state. This prevents the refrigerant accumulated in the reheater 3 and the like from flowing into the indoor heat exchanger 5. Therefore, when the leakage point of the refrigerant exists in the flow path from the 2 nd connection unit N to the 1 st connection unit M via the indoor heat exchanger 5 and the compressor 1, further leakage of the refrigerant into the room can be suppressed. When the indoor refrigerant leakage sensor 41 detects refrigerant leakage, the operation controller 51b can facilitate the specification of the refrigerant leakage site by independently operating the refrigerant circuit from the reheat on-off valve 2 to the 1 st expansion valve 4 via the reheater 3 by setting the reheat on-off valve 2 and the defrost on-off valve 10 in the closed state and setting the 1 st expansion valve 4 in the fully closed state.

When the outdoor-refrigerant leakage sensor 42 detects the refrigerant leakage, that is, when the outdoor-leakage signal is output from the leakage processing unit 51d, the operation control unit 51b closes the cooling on-off valve 6 and completely closes the 1 st expansion valve 4. This can cut off the flow of the refrigerant to the outside of the room, and store the refrigerant outside the room in the indoor heat exchanger 5, thereby suppressing leakage of the refrigerant outside the room. When the leakage of the refrigerant is detected by the outdoor-refrigerant leakage sensor 42, the operation controller 51b can facilitate the determination of the refrigerant leakage position by making the refrigerant circuits from the cooling on-off valve 6 to the 2 nd expansion valve 9 independent by making the cooling on-off valve 6 in the closed state and making the 2 nd expansion valve 9 in the fully closed state.

The storage unit 52 stores an operation program of the control device 50. In addition, various data related to air conditioning control are stored in the storage unit 52. For example, data of the setting contents such as the operation mode, the target temperature, and the target humidity is stored in the storage unit 52. In addition, the storage unit 52 stores information of a threshold value that becomes a reference when detecting the generation of the excessive refrigerant, such as a supercooling threshold value, a discharge threshold value, a high pressure threshold value, or a low pressure threshold value. Among these, the supercooling threshold value, the discharge threshold value, the high pressure threshold value, and the low pressure threshold value are preset, and the settings can be changed as appropriate.

Fig. 3 is an explanatory diagram showing a state of the refrigerant circuit in the dehumidification operation of the air-conditioning apparatus of fig. 1. Fig. 4 is an explanatory diagram showing a state of the refrigerant circuit in the air-conditioning apparatus of fig. 1 during the intermediate operation. Fig. 5 is an explanatory diagram showing a state of the refrigerant circuit in the cooling operation of the air-conditioning apparatus of fig. 1. Fig. 6 is an explanatory diagram showing a state of the refrigerant circuit in the defrosting operation of the air-conditioning apparatus of fig. 1. In fig. 3 to 6, the open-close valve is shown in an open state by a hollow outline, and the closed-open valve is shown in a black outline. In fig. 3 to 6, the flow of the refrigerant is indicated by a broken line with an arrow. Valve control and refrigerant flow in each operation mode will be described with reference to fig. 3 to 6.

[ dehumidification operation ]

As shown in fig. 3, during the dehumidification operation, the cooling on-off valve 6 and the defrosting on-off valve 10 are closed, and the reheat on-off valve 2 is opened. That is, when the dehumidification operation mode is set, the controller 50 opens the reheat on-off valve 2 and closes the cooling on-off valve 6 and the defrost on-off valve 10.

Therefore, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the reheater 3 through the discharge pipe. Here, the 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 and high-pressure gas refrigerant flowing into the reheater 3 exchanges heat with the indoor air passing through the reheater 3 to dissipate heat, condenses, and liquefies. The refrigerant flowing out of the reheater 3 is decompressed by the 1 st expansion valve 4 via the liquid pipe, becomes a two-phase gas-liquid refrigerant, and flows into the indoor heat exchanger 5. The gas-liquid two-phase refrigerant flowing into the indoor heat exchanger 5 absorbs heat and is gasified by heat exchange with the indoor air blown by the indoor air blower 11, and is returned to the compressor 1 as a low-temperature low-pressure gas refrigerant.

Here, the air circulated through the indoor unit 70 by the indoor fan 11 is cooled by the low-temperature low-pressure gas-liquid two-phase refrigerant flowing through the indoor heat exchanger 5, and the temperature thereof is reduced 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. Then, the air having passed through the indoor heat exchanger 5 is heated by the high-temperature and high-pressure gas refrigerant in the reheater 3, and the temperature thereof is raised, thereby lowering the relative humidity.

In this way, during the dehumidification operation, the air-conditioning apparatus 100 releases heat in all the refrigeration cycles in the room by closing the cooling on-off valve 6. That is, the air-conditioning apparatus 100 performs an operation of heating the indoor air by the amount of heat applied to the refrigerant by the compressor 1 and the latent heat of condensation of water vapor in the air. Therefore, the indoor air taken into the air-conditioning apparatus 100 during the dehumidification operation is dehumidified while being heated.

[ intermediate operation ]

As shown in fig. 4, when the intermediate operation of dehumidification and cooling of the air in the air-conditioned space is performed simultaneously, the reheat on-off valve 2 and the cooling on-off valve 6 are in the open state, and the defrost on-off valve 10 is in the closed state. That is, when the intermediate operation mode is set, the controller 50 opens the reheat on-off valve 2 and the cooling on-off valve 6 and closes the defrost on-off valve 10.

Therefore, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 7 through the discharge pipe and flows into the reheater 3. The refrigerant, which has dissipated heat and has been liquefied in the outdoor heat exchanger 7 and the reheater 3, is decompressed by the 1 st expansion valve 4 and the 2 nd expansion valve 9 provided downstream of the liquid pipe, becomes a two-phase gas-liquid refrigerant, and flows into the indoor heat exchanger 5. The two-phase gas-liquid refrigerant flowing into the indoor heat exchanger 5 absorbs heat in the indoor heat exchanger 5 and is gasified, and is sucked into the compressor 1 through the suction pipe. In the intermediate operation, the control device 50 performs on-off control of the outdoor fan 12 in accordance with the outside air temperature and the high pressure, and performs control of the indoor fan 11 so as to be always on.

[ Cooling operation ]

As shown in fig. 5, in the cooling operation for cooling the air in the air conditioning space, the cooling on-off valve 6 is in the open state, and the reheating on-off valve 2 and the defrosting on-off valve 10 are in the closed state. That is, when the cooling operation mode is set, the controller 50 closes the reheat on-off valve 2 and the defrost on-off valve 10, and closes the defrost on-off valve 10.

Therefore, the high-temperature and 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 air-sending device 12 to dissipate heat, condenses, and liquefies. The refrigerant flowing out of the outdoor heat exchanger 7 is decompressed by the 1 st expansion valve 4 via the liquid pipe into a two-phase gas-liquid refrigerant, and flows into the indoor heat exchanger 5. The gas-liquid two-phase refrigerant flowing into the indoor heat exchanger 5 exchanges heat with indoor air blown by the indoor air-sending device 11 to absorb heat and vaporize the refrigerant, and turns into a low-temperature and low-pressure gas refrigerant, which is returned to the compressor 1. That is, the air circulated by the indoor fan 11 is cooled by the low-temperature low-pressure gas-liquid two-phase refrigerant in the indoor heat exchanger 5. The excess refrigerant during the cooling operation is appropriately stored in the reservoir 8.

Here, the cooling operation may be performed when the absolute humidity in the room is low or when the priority for lowering the temperature in the room is high. This is because the relative humidity increases when the temperature of the air decreases due to the cooling operation. Further, when the relative humidity becomes high, there is a problem that comfort is lowered and dew condensation is likely to occur in the room. Further, for example, when the temperature of the air is lowered to be equal to or lower than the dew point due to the cooling operation, moisture in the indoor air condenses on the surface of the indoor heat exchanger 5, thereby increasing the ventilation resistance and reducing the heat exchange capacity.

[ defrosting operation ]

The defrosting operation is a defrosting operation performed when frost adheres to the indoor heat exchanger 5 and performance as a heat exchanger is degraded. As shown in fig. 6, during the defrosting operation, the reheat on-off valve 2 and the cooling on-off valve 6 are closed, and the defrosting on-off valve 10 is opened. That is, when the defrosting operation mode is set, the controller 50 closes the reheat on-off valve 2 and the cooling on-off valve 6 and opens the defrosting on-off valve 10. Therefore, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is decompressed by the 1 st expansion valve 4 via the discharge pipe and the bypass circuit 33, and flows into the indoor heat exchanger 5.

Here, the indoor heat exchanger 5 is heated by the refrigerant, and dissolves frost by exchanging heat with frozen frost. The refrigerant flowing into the indoor heat exchanger 5 is reduced in temperature to a low temperature by heat exchange with frost, and thereafter, is gasified by absorbing heat by heat exchange with the suction pipe, and is returned to the compressor 1 as a low-temperature low-pressure gas refrigerant. At this time, the controller 50 adjusts the amount of the refrigerant passing through the indoor heat exchanger 5 by setting the 1 st expansion valve 4 to the minimum opening degree, thereby preventing the liquefied refrigerant from entering the compressor 1. Further, the control device 50 turns off the indoor fan 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 simply performed.

In the intermediate operation among the above-described operations, the refrigerant is caused to flow to the reheater 3 and the outdoor heat exchanger 7, and therefore the amount of the refrigerant required is relatively large. On the other hand, the amount of refrigerant required for the dehumidification operation is smaller than that for the intermediate operation. This is because, during the dehumidification operation, the refrigerant flows to the reheater 3, but does not flow to the outdoor heat exchanger 7. Therefore, an excessive refrigerant may be generated during the dehumidification operation. If an excessive amount of refrigerant is generated, an abnormality such as a rise in high-pressure may occur. Further, when the temperature difference between the outside air temperature and the indoor temperature is large, the refrigerant is likely to be unevenly distributed, and therefore, there is a concern that an excessive refrigerant may be generated particularly in the cooling operation and the dehumidifying operation.

In consideration of this, the air-conditioning apparatus 100 according to embodiment 1 performs operation switching control for the purpose of equalizing the refrigerant in the refrigerant circuit 30, that is, normalizing the refrigerant distribution, at the time of starting the compressor 1 and at the time of switching the operation mode. After the operation mode is shifted to each operation mode, the air-conditioning apparatus 100 rationalizes the amounts of refrigerant distributed to the reheater 3 and the outdoor heat exchanger 7 by refrigerant distribution control using the state values during operation.

[ operation switching control ]

First, the operation switching control performed by the operation control unit 51b before the transition to the various operation modes will be described. Fig. 7 is an explanatory diagram showing timing at which the control device of fig. 1 performs operation switching control. As shown in fig. 7, when the cooling operation, the intermediate operation, or the dehumidifying operation is instructed to start the compressor 1, the operation controller 51b starts the instructed operation after performing the operation switching control. When the cooling operation is switched to the intermediate operation or the dehumidifying operation, when the intermediate operation is switched to the cooling operation or the dehumidifying operation, or when the dehumidifying operation is switched to the intermediate operation or the cooling operation, the operation control unit 51b starts the instructed operation, that is, the switched operation after the operation switching control is performed.

The user can perform an operation for instructing the start of operation in a certain operation mode and an operation for instructing switching of the operation mode via a controller device such as a remote controller. When receiving an operation for instructing the start of operation, the controller device transmits an operation instruction to the setting processing unit 51a of the controller 50. Upon receiving an operation for instructing switching of the operation mode, the controller device transmits an operation switching instruction to the setting processing unit 51a of the controller 50. Upon receiving an operation instruction or an operation switching instruction from the controller device, the setting processing portion 51a executes operation switching control.

In the operation switching control, the operation control unit 51b opens both the reheat on-off valve 2 and the cooling on-off valve 6 and closes the defrost on-off valve 10, as in the intermediate operation. The operation controller 51b performs a refrigerant averaging process for averaging the refrigerant in the refrigerant circuit 30 using the 1 st expansion valve 4 disposed downstream of the reheater 3 and the 2 nd expansion valve 9 disposed downstream of the outdoor heat exchanger 7.

In the refrigerant leveling process, the operation controller 51b configures the refrigeration cycle by SC control (subcooling control) using the 2 nd expansion valve 9 so that the amount of refrigerant distributed in the outdoor heat exchanger 7 is in an appropriate state. That is, the operation controller 51b controls the opening degree of the 2 nd expansion valve 9 so that the degree of subcooling by the outdoor heat exchanger 7 falls within the appropriate range of the condenser, for example, using the temperature of the refrigerant at the outlet of the outdoor heat exchanger 7. The appropriate range for the condenser in embodiment 1 is a range in which the determination value X is defined as a reference and which indicates that the amount of refrigerant in the outdoor heat exchanger 7 is appropriate. The determination value X is set to, for example, 5[K, and can be appropriately changed according to the configuration of the refrigerant circuit 30 and the like. Hereinafter, the degree of supercooling by the outdoor heat exchanger 7, that is, the degree of supercooling by the condenser is also referred to as "external liquid SC".

More specifically, the appropriate condenser range is a range from a value obtained by subtracting the coefficient α from the determination value X to a value obtained by adding the coefficient β to the determination value X. The determination value X, the coefficient α, and the coefficient β are set to appropriate amounts of the refrigerant distributed in the outdoor heat exchanger 7 if the external liquid SC is within the appropriate range of the condenser. The coefficient α and the coefficient β are each 0 or a positive value, and are set according to the configuration of the refrigerant circuit 30, and can be changed as appropriate. The coefficient α and the coefficient β may be the same value or different values. The coefficients α and β can be set to values of about 1[K to 2[K ].

The operation controller 51b obtains the external liquid SC using the external liquid temperature measured by the refrigerant temperature sensor 69. When the external liquid SC is obtained, the operation control unit 51b obtains the high pressure from the pressure sensor 62 and obtains the internal liquid temperature from the refrigerant temperature sensor 67. The operation controller 51b calculates the condensation temperature CT by saturation conversion of the high-pressure, and calculates the external liquid SC by subtracting the external liquid temperature from the calculated condensation temperature CT. The operation controller 51b controls the 2 nd expansion valve 9 based on the obtained external liquid SC, thereby adjusting the amount of refrigerant distributed in the outdoor heat exchanger 7. The operation controller 51b may calculate the condensation temperature CT using the condenser outlet pressure obtained from the pressure sensor 64 instead of the high pressure obtained from the pressure sensor 62.

In the refrigerant leveling process, the operation controller 51b forms the refrigeration cycle by SH control (Super heat control) using the 1 st expansion valve 4, thereby performing a process of accumulating the refrigerant in the reheater 3 and the outdoor heat exchanger 7 while preventing liquid return due to excess refrigerant. That is, the operation controller 51b executes SH control of the 1 st expansion valve 4 so that the degree of Superheat (SH) by the indoor heat exchanger 5 falls within the refrigerant adjustment range. This allows excess refrigerant to be stored in the receiver 8, and prevents liquid from returning to the compressor 1. Hereinafter, the degree of superheat by the indoor heat exchanger 5, that is, the degree of superheat by the evaporator is also referred to as "suction SH". The refrigerant adjustment range according to embodiment 1 is a range in which the determination value P is defined as a reference and the refrigerant distribution in the refrigerant circuit 30 is appropriate.

More specifically, the refrigerant adjustment range is a range from a value obtained by subtracting the coefficient γ from the determination value P to a value obtained by adding the coefficient δ to the determination value P. The determination value P, the coefficient γ, and the coefficient δ are set so that the refrigerant is accumulated in each condenser when the suction SH is within the refrigerant adjustment range, and liquid return due to an excessive refrigerant can be prevented. The determination value P is set to, for example, 5[K, and can be appropriately changed according to the configuration of the refrigerant circuit 30 and the like. The coefficient γ and the coefficient δ are each 0 or a positive value, and can be appropriately changed depending on the configuration of the refrigerant circuit 30 and the like. The coefficient γ and the coefficient δ may be the same value or different values. The coefficient γ and the coefficient δ may be set to values of about 1[K to 2[K ].

When the suction SH is determined, the operation control unit 51b obtains the low pressure from the pressure sensor 61 and obtains the suction temperature from the refrigerant temperature sensor 65. The operation control unit 51b calculates the evaporation temperature ET by performing saturation conversion on the low pressure, and calculates the suction SH by subtracting the evaporation temperature ET from the suction temperature. However, a refrigerant temperature sensor may be provided in the indoor heat exchanger 5, and the control device 50 may use the measured temperature of the refrigerant temperature sensor as the evaporation temperature ET.

That is, in the refrigerant averaging process, the operation control unit 51b performs determination as to whether or not averaging conditions of "external liquid SC ≈ determination value X" and "suction SH ≈ determination value P" are satisfied. When the averaging condition is satisfied for a predetermined set time, the operation control unit 51b starts the instructed operation, that is, the operation indicated by the operation instruction or the operation switching instruction. Even if the averaging condition is not satisfied for the set time, the operation control unit 51b starts the instructed operation when the set time has elapsed from the start of the operation switching control. The setting time is set to, for example, 5 minutes, and can be appropriately changed according to the configuration of the refrigerant circuit 30 and the like. The averaging conditions will be described in detail in the following operation description.

[ refrigerant distribution control ]

Next, the refrigerant distribution control performed by the operation control unit 51b based on the operating state value after the transition to each operation will be described. In embodiment 1, when the operation switching control described above is executed to switch to the cooling operation or the dehumidifying operation, the operation control unit 51b executes refrigerant distribution control based on the state value during the operation.

(control of refrigerant distribution during Cooling operation)

During the cooling operation, the operation controller 51b controls the opening degree of the 2 nd expansion valve 9, for example, using the temperature of the refrigerant at the outlet of the outdoor heat exchanger 7, and controls the opening/closing state of the reheat opening/closing valve 2 and the opening degree of the 1 st expansion valve 4. That is, the operation controller 51b obtains the external liquid temperature SC using the external liquid temperature measured by the refrigerant temperature sensor 69. When obtaining the external liquid SC, the operation control unit 51b obtains the high pressure from the pressure sensor 62 and obtains the external liquid temperature from the refrigerant temperature sensor 69. The operation controller 51b calculates the condensation temperature CT by performing saturation conversion on the high-pressure, and calculates the external liquid SC by subtracting the external liquid temperature from the calculated condensation temperature CT. The operation controller 51b adjusts the amount of refrigerant distributed in the outdoor heat exchanger 7 by controlling the 2 nd expansion valve 9 and controlling the reheat opening/closing valve 2 and the 1 st expansion valve 4 based on the determined external liquid SC. The operation controller 51b may calculate the condensing temperature CT using the condenser outlet pressure obtained from the pressure sensor 64 instead of the high pressure obtained from the pressure sensor 62.

The operation controller 51b determines the excess or deficiency of the refrigerant amount during the cooling operation based on the external liquid SC. That is, the operation controller 51b determines whether or not the external liquid SC is within the appropriate range of the refrigerant amount. The appropriate refrigerant quantity range according to embodiment 1 is a range in which the determination value Y is defined as a reference and the refrigerant quantity distributed in the outdoor heat exchanger 7 is indicated as appropriate. The determination value Y is set to, for example, 5[K, and can be changed as appropriate depending on the configuration of the refrigerant circuit 30 and the like.

More specifically, the appropriate range of the amount of refrigerant during the cooling operation is a range from a value obtained by subtracting the coefficient a from the determination value Y to a value obtained by adding the coefficient b to the determination value Y. The coefficient a and the coefficient b are each 0 or a positive value, and may be appropriately changed depending on the configuration of the refrigerant circuit 30 and the like. The determination value Y, the coefficient a, and the coefficient b are set so that the refrigerant distributed in the outdoor heat exchanger 7 during the cooling operation becomes an appropriate amount if the external liquid SC is within the appropriate refrigerant amount range. Hereinafter, the lower limit value of the appropriate refrigerant amount range, i.e., the value obtained by subtracting the coefficient a from the determination value Y, is referred to as "lower cooling limit value", and the upper limit value of the appropriate refrigerant amount range, i.e., the value obtained by adding the coefficient b to the determination value Y, is also referred to as "upper cooling limit value". The coefficient a and the coefficient b may be the same value or different values.

Therefore, the amount of the external liquid SC in the appropriate range of the refrigerant amount corresponds to the amount of the refrigerant distributed in the outdoor heat exchanger 7. The fact that the external liquid SC is larger than the upper cooling limit value corresponds to an excess of refrigerant distributed to the outdoor heat exchanger 7. The external liquid SC being less than the cooling lower limit value corresponds to a shortage of the refrigerant distributed in the outdoor heat exchanger 7.

When the external liquid SC is less than the cooling lower limit value, the operation controller 51b determines whether both an outdoor high-pressure protection condition in which the condensation temperature CT is lower than a determination threshold value for avoiding high-pressure abnormality and an indoor refrigerant discharge condition in which the internal liquid temperature is higher than the evaporation temperature ET are satisfied.

The outdoor high-pressure protection condition is a condition for preventing high-pressure abnormality when the distribution of refrigerant is increased on the outdoor side. In embodiment 1, the determination threshold value in the cooling operation is a value obtained by subtracting the determination value Y from the guard condensing temperature CTmax. The protection condensation temperature CTmax is a threshold value for performing high-voltage protection, and is set higher than the ordinary condensation temperature CT. That is, the operation controller 51b performs the high-voltage protection when the condensation temperature CT reaches the protection condensation temperature CTmax. The indoor refrigerant discharge condition is a condition for determining whether or not the refrigerant can be discharged based on the pressure difference when the refrigerant is discharged from the indoor side, that is, when the refrigerant is replenished from the reheater 3 to the indoor heat exchanger 5.

When the outdoor high-pressure protection condition and the indoor refrigerant discharge condition are satisfied, the operation controller 51b sets the 1 st expansion valve 4 to the minimum opening degree, and sets the state in which the refrigerant flows from the reheater 3 to the indoor heat exchanger 5, thereby adjusting the amount of the refrigerant passing through the indoor heat exchanger 5. Then, when the condition that the external liquid SC is within the storage reference range is satisfied during a period from when the 1 st expansion valve 4 is set to the minimum opening degree until the adjustment reference time elapses, the operation controller 51b sets the 1 st expansion valve 4 to the fully closed state to terminate the refrigerant distribution control. The adjustment reference time is set to, for example, 5 minutes, and can be changed as appropriate.

When the external liquid SC is larger than the cooling upper limit value, the operation controller 51b determines whether or not the temperature of the internal liquid measured by the refrigerant temperature sensor 67 is smaller than the condensation temperature CT. This determination is used to determine whether or not the refrigerant can be discharged based on the pressure difference when the refrigerant is discharged to the indoor side. That is, when the temperature of the internal liquid is lower than the condensation temperature CT, the operation controller 51b opens the reheat on-off valve 2 to disperse the refrigerant flowing through the outdoor heat exchanger 7 to the reheater 3, thereby accumulating the refrigerant in the reheater 3.

When the condition that the external liquid SC is within the storage reference range is satisfied during a period from when the reheat on-off valve 2 is opened until the opening/closing reference time elapses, the operation controller 51b closes the reheat on-off valve 2, and terminates the refrigerant distribution control. The opening/closing reference time is set to, for example, 5 minutes, and can be changed as appropriate. The accumulation reference range during the cooling operation is a range corresponding to an appropriate amount of accumulated refrigerant in the reheater 3 with the determination value Y defined as a reference. More specifically, the storage reference range is a range from a value obtained by subtracting the coefficient c from the determination value Y to a value obtained by adding the coefficient d to the determination value Y. The determination value Y, the coefficient c, and the coefficient d are set such that the amount of accumulated refrigerant in the reheater 3, that is, the amount of refrigerant distributed to the outdoor heat exchanger 7 is appropriate when the external liquid SC is within the accumulation reference range. The coefficient c and the coefficient d are each 0 or a positive value, and can be appropriately changed according to the configuration of the refrigerant circuit 30 and the like. The coefficient c and the coefficient d may be the same value or different values.

(control of refrigerant distribution in dehumidification operation)

During the dehumidification operation, the operation controller 51b controls the opening degree of the 1 st expansion valve 4 using, for example, the temperature of the refrigerant at the outlet of the reheater 3. That is, the operation controller 51b determines the degree of supercooling by the reheater 3 using the temperature of the internal liquid measured by the refrigerant temperature sensor 67. Hereinafter, the degree of supercooling by the reheater 3 is also referred to as "internal liquid SC". When the internal liquid SC is obtained, the operation control unit 51b obtains the high pressure from the pressure sensor 62 and obtains the internal liquid temperature from the refrigerant temperature sensor 67. The operation control unit 51b calculates the condensation temperature by performing saturation conversion on the high-pressure, and calculates the internal liquid SC by subtracting the internal liquid temperature from the condensation temperature. The operation controller 51b controls the 1 st expansion valve 4 and the cooling on-off valve 6 and the 2 nd expansion valve 9 based on the obtained internal liquid SC, thereby adjusting the amount of refrigerant distributed to the reheater 3. The operation controller 51b may calculate the condensation temperature by using the reheater outlet pressure obtained from the pressure sensor 63 instead of the high pressure obtained from the pressure sensor 62.

The operation controller 51b determines the excess or deficiency of the refrigerant amount during the dehumidification operation based on the internal liquid SC. That is, the operation controller 51b determines whether or not the internal liquid SC is within the appropriate range of the refrigerant amount. The appropriate refrigerant amount range is a range in which the set determination value Z is defined as a reference and which indicates that the amount of refrigerant distributed to the reheater 3 is appropriate. The determination value Z is set to, for example, 5[K, and can be changed as appropriate depending on the configuration of the refrigerant circuit 30 and the like.

In embodiment 1, the appropriate range of the amount of refrigerant during the dehumidification operation is a range from a value obtained by subtracting the coefficient e from the determination value Z to a value obtained by adding the coefficient f to the determination value Z. The coefficient e and the coefficient f are each 0 or a positive value, and may be appropriately changed depending on the configuration of the refrigerant circuit 30 and the like. The coefficient e and the coefficient f may be the same value or different values. The determination value Z, the coefficient e, and the coefficient f are set so that the amount of refrigerant distributed to the reheater 3 during the dehumidification operation is appropriate if the internal liquid SC is within the appropriate range of the amount of refrigerant. Hereinafter, the value obtained by subtracting the coefficient e from the determination value Z, which is the lower limit of the appropriate range of the amount of refrigerant, is referred to as the "dehumidification lower limit value", and the value obtained by adding the coefficient f to the determination value Z, which is the upper limit of the appropriate range of the amount of refrigerant, is referred to as the "dehumidification upper limit value".

Therefore, the amount of the internal liquid SC in the appropriate range of the amount of the refrigerant corresponds to the amount of the refrigerant distributed to the reheater 3. The fact that the internal liquid SC is larger than the dehumidification upper limit value corresponds to an excessive amount of refrigerant distributed to the reheater 3. The internal liquid SC being less than the dehumidification lower limit value corresponds to a shortage of the refrigerant distributed to the reheater 3.

If the internal liquid SC is less than the dehumidification lower limit value, the operation control unit 51b determines whether both an indoor high-pressure protection condition in which the condensation temperature CT is lower than a determination threshold value for avoiding high-pressure abnormality and an outdoor refrigerant discharge condition in which the external liquid temperature is higher than the evaporation temperature ET are satisfied. The indoor high-pressure protection condition is a condition for preventing high-pressure abnormality when the distribution of the refrigerant is increased at the indoor side. In embodiment 1, the determination threshold value during the dehumidification operation is a value obtained by subtracting the determination value Z from the protection condensation temperature CTmax. The outdoor refrigerant discharge condition is a condition for determining whether or not discharge of refrigerant from the outdoor side is possible, that is, whether or not discharge is possible due to a pressure difference when the refrigerant is replenished from the outdoor heat exchanger 7 to the main circuit 31.

When the indoor high-pressure protection condition and the outdoor refrigerant discharge condition are satisfied, the operation controller 51b sets the 2 nd expansion valve 9 to the minimum opening degree, and adjusts the amount of the refrigerant passing through the indoor heat exchanger 5 in a state where the refrigerant flows from the outdoor heat exchanger 7 to the indoor heat exchanger 5. When the condition that the content liquid SC is within the storage reference range is satisfied during a period from when the 2 nd expansion valve 9 is set to the minimum opening degree until the adjustment reference time elapses, the operation control unit 51b sets the 2 nd expansion valve 9 to the fully closed state to end the refrigerant distribution control.

When the internal liquid SC is larger than the dehumidification upper limit value, the operation controller 51b determines whether or not the external liquid temperature measured by the refrigerant temperature sensor 69 is lower than the condensation temperature CT. This determination is used to determine whether or not the refrigerant can be discharged based on the pressure difference when the refrigerant is discharged to the outdoor side. That is, when the external liquid temperature is lower than the condensation temperature CT, the operation controller 51b opens the cooling on-off valve 6, and disperses the refrigerant flowing to the reheater 3 toward the outdoor heat exchanger 7, thereby accumulating the refrigerant in the outdoor heat exchanger 7 and the like.

When the condition that the internal liquid SC is within the storage reference range is satisfied during a period from when the cooling on-off valve 6 is opened until the opening/closing reference time elapses, the control device 50 closes the cooling on-off valve 6, and ends the refrigerant distribution control. The storage reference range during the dehumidification operation is a range corresponding to an appropriate amount of refrigerant stored in the outdoor heat exchanger 7 with the determination value Z defined as a reference. In embodiment 1, the accumulation reference range is a range from a value obtained by subtracting a coefficient g from the determination value Z to a value obtained by adding a coefficient h to the determination value Z. The determination value Z, the coefficient g, and the coefficient h are set so that the amount of refrigerant accumulated in the outdoor heat exchanger 7, that is, the amount of refrigerant distributed to the reheater 3 is appropriate when the internal liquid SC is within the accumulation reference range. The coefficients g and h are each 0 or a positive value, and can be appropriately changed depending on the configuration of the refrigerant circuit 30 and the like. The coefficient g and the coefficient h may be the same value or different values. The coefficients a to h may be set to values of about 1[K to 2[K.

[ refrigerant quantity adjusting operation ]

In the intermediate operation among the above-described operations, the refrigerant is caused to flow to the reheater 3 and the outdoor heat exchanger 7, and therefore the amount of the refrigerant required is relatively large. On the other hand, the amount of refrigerant required for the dehumidification operation is less than that for the intermediate operation. This is because, during the dehumidification operation, the refrigerant flows to the reheater 3, but does not flow to the outdoor heat exchanger 7. Therefore, an excessive refrigerant may be generated during the dehumidification operation. If an excessive amount of refrigerant is generated, an abnormality such as a rise in high-pressure may occur.

Therefore, when excess refrigerant is generated during the dehumidification operation, the air-conditioning apparatus 100 according to embodiment 1 performs the refrigerant amount adjustment operation. The refrigerant amount adjustment control performed by the operation control unit 51b when excess refrigerant is generated will be described below.

When the occurrence of the extra refrigerant is detected during the dehumidification operation, the operation controller 51b opens both the reheat on-off valve 2 and the cooling on-off valve 6, and closes the defrost on-off valve 10, as in the intermediate operation. The operation controller 51b performs refrigerant amount adjustment control using the 1 st expansion valve 4 disposed downstream of the reheater 3 and the 2 nd expansion valve 9 disposed downstream of the outdoor heat exchanger 7. That is, the operation controller 51b forms the refrigeration cycle by the SC control to ensure the performance of the reheater 3, and causes the receiver 8 to accumulate the extra refrigerant that has passed through the outdoor heat exchanger 7 by the SH control.

The operation control unit 51b of embodiment 1 executes the SC control of the 1 st expansion valve 4 so as to ensure the internal liquid SC to be equal to or greater than the reheat determination value. The SC control of the operation controller 51b ensures the reheating amount of the reheater 3 required during the dehumidification operation, and can exhibit a sufficient dehumidification capability.

The operation controller 51b controls the opening degree of the 1 st 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 obtains the internal liquid SC in the same manner as described above, and controls the 1 st expansion valve 4 so that the obtained internal liquid SC becomes a set value. This enables the amount of reheat performed by the reheater 3 to be controlled to exhibit the set dehumidification capacity. The operation controller 51b executes SH control of the 2 nd expansion valve 9 so as to maintain the suction SH determined in the same manner as described above at the condensation determination value or more. Thereby, the excess refrigerant is accumulated in the reservoir 8.

The operation controller 51b may control the opening degree of the 1 st expansion valve 4 using the temperature of the air blown out of the air-conditioning apparatus 100, that is, the temperature of the air passing through the reheater 3. In this case, an air temperature sensor is provided in advance at the outlet of the indoor unit 70, and the operation control unit 51b may control the opening degree of the 1 st expansion valve 4 so that the temperature measured by the air temperature sensor becomes the set target temperature. Here, the temperature of the air blown out of the air-conditioning apparatus 100 is the temperature of the air blown out from the indoor unit 70 into the air-conditioned space, and hereinafter, is also referred to as the blow-out temperature.

Fig. 8 is a flowchart showing an operation related to the operation switching control of the control device of fig. 1. The flow of operations related to the operation switching control will be described with reference to fig. 8.

The control device 50 maintains the current operation state until receiving an operation command or an operation switching command from the controller device (step S101/no). Upon receiving the operation command or the operation switching command from the controller device (step S101/yes), the controller 50 starts operation switching control. That is, the controller 50 opens the reheat on-off valve 2 and the cooling on-off valve 6 and closes the defrost on-off valve 10 (step S102). Then, the control device 50 performs the refrigerant averaging process using the 1 st expansion valve 4 and the 2 nd expansion valve 9. That is, the controller 50 starts the SC control using the 2 nd expansion valve 9 and the SH control using the 1 st expansion valve 4 (step S103).

Next, the control device 50 determines whether or not an averaging condition is satisfied in which the external liquid SC is within the condenser proper range and the suction SH is within the refrigerant adjustment range (step S104). When the averaging condition is satisfied (step S104/yes), the control device 50 starts the operation instructed by the operation command or the operation switching command (step S106). If the averaging condition is not satisfied (step S104/no), the control device 50 determines whether or not the averaging condition is satisfied at predetermined intervals until the elapsed time from the start of the operation switching control reaches the set time. Here, the interval at which the determination processing of step S104 is performed may be constant or may be shortened in accordance with the elapsed time (step S105/no, step S104).

Even if the averaging condition is not satisfied (step S104/no), if the elapsed time from the start of the operation switching control reaches the set time, the control device 50 ends the operation switching control and starts the operation instructed by the operation command or the operation switching command (step S106).

Fig. 9 is a flowchart illustrating the refrigerant distribution control during the cooling operation according to the control device of fig. 1. The flow of the operation in the refrigerant distribution control during the cooling operation will be described with reference to fig. 9.

When the cooling operation is started and a predetermined time has elapsed, the control device 50 determines whether the external liquid SC is within the appropriate range of the refrigerant amount (step S201). When the external liquid SC is within the appropriate range of the refrigerant amount (step S201/yes), the control device 50 ends the refrigerant distribution control (step S213).

When the external liquid SC is larger than the cooling upper limit value (Y + b) (no in step S201, yes in step S202), the control device 50 determines whether or not the internal liquid temperature measured by the refrigerant temperature sensor 67 is smaller than the condensation temperature CT (step S203).

If the internal liquid temperature is equal to or higher than the condensation temperature CT (no in step S203), the control device 50 ends the refrigerant distribution control (step S213). On the other hand, if the internal liquid temperature is lower than the condensation temperature CT (step S203/yes), the controller 50 opens the reheat on-off valve 2 because the refrigerant can be accumulated in the reheater 3 based on the pressure difference. That is, the controller 50 changes the reheat opening/closing valve 2 from the closed state to the open state (step S204).

Next, the controller 50 determines whether or not the external liquid SC is within the storage reference range (step S205). When the external liquid SC is within the accumulation reference range, the controller 50 closes the reheat opening/closing valve 2 to shut off the refrigerant flowing to the reheater 3 (step S207), and ends the refrigerant distribution control (step S213). When the external liquid SC is out of the storage reference range (step S205/no), the control device 50 repeats the determination process of step S205 at predetermined intervals until the elapsed time from the start of the refrigerant distribution control reaches the opening/closing reference time. Here, the interval at which the determination processing of step S205 is performed may be constant or may be shortened in accordance with the elapsed time (step S206/no, step S205).

Even if the external liquid SC is outside the storage reference range (step S205/no), when the elapsed time from the start of the refrigerant distribution control reaches the opening/closing reference time, the controller 50 closes the reheat on-off valve 2 (step S207) and ends the refrigerant distribution control (step S213).

When the external liquid SC is smaller than the cooling lower limit value (Y-a) (no in step S201 and no in step S202), the control device 50 determines whether both the outdoor high-pressure protection condition and the indoor refrigerant discharge condition are satisfied (step S208). When it is determined that the outdoor high-pressure protection condition is satisfied and the indoor refrigerant discharge condition is satisfied (yes in step S208), the control device 50 adjusts the 1 st expansion valve 4 to the minimum opening degree (step S209).

Next, the control device 50 determines whether or not the external liquid SC is within the storage reference range, as in step S205 (step S210). When the external liquid SC is within the storage reference range, the controller 50 completely closes the 1 st expansion valve 4 (step S212), and ends the refrigerant distribution control (step S213).

When the external liquid SC is out of the storage reference range (step S210/no), the control device 50 repeats the determination process of step S210 at predetermined intervals until the elapsed time from the start of the refrigerant distribution control reaches the adjustment reference time (step S210/no, step S211).

Even if the external liquid SC is outside the storage reference range (step S210/no), the control device 50 completely closes the 1 st expansion valve 4 when the elapsed time from the start of the refrigerant distribution control reaches the adjustment reference time (step S212), and ends the refrigerant distribution control (step S213). When it is determined that at least one of the outdoor high-pressure protection condition and the indoor refrigerant discharge condition is not satisfied (no at step S208), the control device 50 ends the refrigerant distribution control (step S213).

The control device 50 performs a normal cooling operation until a predetermined period of time elapses (no at step S214), and starts the process at step S201 when the predetermined period of time elapses (yes at step S214). That is, the control device 50 repeatedly executes a series of processes of steps S201 to S213 at regular intervals. In this way, if the refrigerant distribution control, which is a series of processes in steps S201 to S213, is performed once during the cooling operation, the air-conditioning apparatus 100 does not perform the refrigerant distribution control until a certain period of time has elapsed. Therefore, since frequent opening and closing operations of the 1 st expansion valve 4 and the reheat opening and closing valve 2 can be avoided, deterioration of the 1 st expansion valve 4 and the reheat opening and closing valve 2 can be prevented, and reliability can be improved. As the determination value Y in steps S205 and S210, a value different from the determination value Y in step S201 may be used.

Fig. 10 is a flowchart illustrating refrigerant distribution control during the dehumidification operation according to the control device of fig. 1. The flow of operations in the refrigerant distribution control during the dehumidification operation will be described with reference to fig. 10.

When the dehumidification operation is started and a predetermined time elapses, the control device 50 determines whether or not the internal liquid SC is within the appropriate range of the refrigerant amount (step S301). When the external liquid SC is within the appropriate range of the refrigerant amount (step S301/yes), the control device 50 ends the refrigerant distribution control (step S313).

If the internal liquid SC is greater than the dehumidification upper limit value (Z + f) (no in step S301, yes in step S302), the control device 50 determines whether or not the external liquid temperature measured by the refrigerant temperature sensor 69 is less than the condensation temperature CT (step S303).

When the external liquid temperature is equal to or higher than the condensation temperature CT (no in step S303), the control device 50b ends the refrigerant distribution control (step S313). On the other hand, if the external liquid temperature is lower than the condensation temperature CT (step S303/yes), the control device 50 opens the cooling on-off valve 6. That is, the controller 50 changes the cooling on-off valve 6 from the closed state to the open state (step S304).

Next, the control device 50 determines whether or not the internal liquid SC is within the storage reference range. However, the determination value Z of step S305 may be a value different from the determination value Z of step S301 (step S305).

When the internal liquid SC is within the storage reference range, the controller 50 closes the cooling on/off valve 6 to shut off the refrigerant flowing to the outdoor heat exchanger 7 (step S307), and ends the refrigerant distribution control (step S313). When the internal liquid SC is out of the storage reference range (no at step S305), the control device 50 repeats the determination process at step S305 at predetermined intervals until the elapsed time from the start of the refrigerant distribution control reaches the opening/closing reference time. Here, the interval at which the determination processing of step S305 is performed may be constant or may be shortened in accordance with the elapsed time (step S306/no, step S305).

Even if the internal liquid SC is outside the storage reference range (step S305/no), the control device 50 closes the cooling on-off valve 6 (step S307) when the elapsed time from the start of the refrigerant distribution control reaches the open/close reference time, and ends the refrigerant distribution control (step S313).

When the internal liquid SC is smaller than the dehumidification lower limit value (Z-e) (no in step S301 and no in step S302), the control device 50 determines whether or not both the indoor high-pressure protection condition and the outdoor refrigerant discharge condition are satisfied (step S308). If it is determined that the indoor high-pressure protection condition is satisfied and the outdoor refrigerant discharge condition is satisfied (step S308/yes), the control device 50 adjusts the 2 nd expansion valve 9 to the minimum opening degree (step S309).

Next, the control device 50 determines whether or not the internal liquid SC is within the storage reference range, similarly to step S305 (step S310). When the internal liquid SC is within the storage reference range, the controller 50 completely closes the 2 nd expansion valve 9 (step S312), and ends the refrigerant distribution control (step S313).

When the internal liquid SC is out of the storage reference range (step S310/no), the control device 50 repeats the determination process of step S310 at predetermined intervals until the elapsed time from the start of the refrigerant distribution control reaches the adjustment reference time (step S310/no, step S311).

Even if the internal liquid SC is outside the storage reference range (step S310/no), the control device 50 completely closes the 2 nd expansion valve 9 when the elapsed time from the start of the refrigerant distribution control reaches the adjustment reference time (step S312), and ends the refrigerant distribution control (step S313). When determining that at least one of the indoor high-pressure protection condition and the outdoor refrigerant discharge condition is not satisfied (no at step S308), the control device 50 ends the refrigerant distribution control (step S313).

The controller 50 performs the normal cooling operation until a predetermined period of time elapses (no at step S314), and starts the process at step S301 when the predetermined period of time elapses (yes at step S314). That is, the control device 50 repeatedly executes a series of processes of steps S301 to S313 at regular intervals. In this way, if the air-conditioning apparatus 100 performs the refrigerant distribution control, which is a series of the processes of steps S301 to S313, once during the dehumidification operation, the refrigerant distribution control is not performed until a certain period of time has elapsed. Therefore, since frequent opening and closing operations of the 2 nd expansion valve 9 and the cooling on-off valve 6 can be avoided, deterioration of the 2 nd expansion valve 9 and the cooling on-off valve 6 can be prevented, and reliability can be improved. As the determination value Z in steps S305 and S310, a value different from the determination value Z in step S301 may be used.

[ treatment and operation at the time of refrigerant leakage ]

Next, an example of the processing contents of the control device 50 and the operation contents of each opening/closing valve and each expansion valve when refrigerant leakage occurs will be described.

(case where the refrigerant leakage is detected by the indoor refrigerant leakage sensor 41)

When the indoor refrigerant leakage sensor 41 detects refrigerant leakage, the control device 50 operates the compressor 1 to perform the evacuation operation by closing the reheat opening/closing valve 2, closing the defrost opening/closing valve 10, opening the cooling opening/closing valve 6, and completely closing the 2 nd expansion valve 9. When the evacuation operation is performed, the control device 50 may set the rotation speed of the indoor fan 11 and the outdoor fan 12 to be higher than that in the normal operation. By the valve control and the evacuation operation as described above, when the refrigerant leaks in the room, the refrigerant can be retained in the piping from the cooling opening/closing valve 6 to the outdoor heat exchanger 7, the piping from the outdoor heat exchanger 7 to the receiver 8, and the piping from the receiver 8 to the 2 nd expansion valve 9.

When the suction-side pressure is lower than the set value or the discharge-side pressure is higher than the set value, the controller 50 stops the operation of the compressor 1. Then, the controller 50 closes the cooling on-off valve 6 after stopping the operation of the compressor 1. In this way, by closing the cooling on-off valve 6 after the compressor 1 is stopped, the reverse flow of the refrigerant can be suppressed. Further, by stopping the operation of the air-conditioning apparatus 100 in stages as described above, it is possible to improve safety.

After the evacuation operation is performed, if there is no obstacle even when the refrigerant is circulated to the compressor 1, the outdoor heat exchanger 7, the 2 nd expansion valve 9, and the indoor heat exchanger 5, the cooling operation can be performed by opening the cooling on-off valve 6. Since the temperature of the air-conditioned space can be prevented from rising by performing the cooling operation, the reduction in comfort can be suppressed. Here, as a situation where there is no obstacle even in circulating the refrigerant to the compressor 1, the outdoor heat exchanger 7, the 2 nd expansion valve 9, and the indoor heat exchanger 5, a case is conceivable where a leakage portion of the refrigerant is determined between the reheat opening/closing valve 2 and the 1 st expansion valve 4, between the defrost opening/closing valve 10 and the 1 st expansion valve 4, or the like.

(case where the outdoor refrigerant leakage sensor 42 detects refrigerant leakage)

When the outdoor refrigerant leakage sensor 42 detects refrigerant leakage, the controller 50 operates the compressor 1 to perform the evacuation operation by opening the reheat opening/closing valve 2, closing the defrost opening/closing valve 10, closing the cooling opening/closing valve 6, and completely closing the 1 st expansion valve 4. When the evacuation operation is performed, the control device 50 may increase the rotation speed of the indoor fan 11 and the outdoor fan 12 to be higher than that in the normal operation. By the valve control and the evacuation operation as described above, when the refrigerant leaks outdoors, the refrigerant can be stored in the reheater 3 and the piping from the reheater 3 to the 1 st expansion valve 4.

When the suction-side pressure is lower than the set value or the discharge-side pressure is higher than the set value, the controller 50 stops the operation of the compressor 1. Then, controller 50 closes reheat opening/closing valve 2 after stopping the operation of compressor 1. In this way, by closing reheat opening/closing valve 2 after compressor 1 is stopped, the reverse flow of refrigerant can be suppressed. Further, by stopping the operation of the air-conditioning apparatus 100 in stages as described above, safety can be improved.

After the evacuation operation is performed, if there is no obstacle even in circulating the refrigerant to the compressor 1, the reheater 3, the 1 st expansion valve 4, and the indoor heat exchanger 5, the dehumidification operation can be performed by opening the reheat opening/closing valve 2. Since the humidity in the air-conditioned space can be prevented from increasing by continuing the dehumidification operation, the reduction in comfort can be suppressed. It is also conceivable that, as a situation in which there is no obstacle in circulating the refrigerant to the compressor 1, the reheater 3, the 1 st expansion valve 4, and the indoor heat exchanger 5, a location of leakage of the refrigerant is determined between the cooling on-off valve 6 and the 2 nd expansion valve 9, or the like.

As described above, in the air-conditioning apparatus 100 according to embodiment 1, when the amount of the refrigerant in the internal liquid SC during the dehumidification operation is outside the appropriate range, the control device 50 controls the cooling on-off valve 6 or the 2 nd expansion valve 9 based on the result of the determination using the external liquid temperature. Therefore, since the amount of refrigerant in the reheater 3 can be adjusted according to the outside temperature, the uneven distribution of refrigerant in the refrigerant circuit 30 can be suppressed, and the operating efficiency can be improved.

When the degree of supercooling by the reheater 3 is smaller than the lower limit value of the appropriate refrigerant amount range, the control device 50 determines whether both the indoor high-pressure protection condition and the outdoor refrigerant discharge condition are satisfied, and when both the indoor high-pressure protection condition and the outdoor refrigerant discharge condition are satisfied, sets the second expansion valve 9 to the minimum opening degree for a predetermined period. Therefore, the refrigerant accumulated in the outdoor heat exchanger 7 and the like can be supplemented to the main circuit 31, and therefore, the shortage of the refrigerant in the reheater 3 can be eliminated.

When the condition that the degree of supercooling by the reheater 3 is within the storage reference range is satisfied during a period from when the 2 nd expansion valve 9 is set to the minimum opening degree until the adjustment reference time elapses, the controller 50 sets the 2 nd expansion valve 9 to the fully closed state. Therefore, the instructed operation can be promptly started at a timing at which the shortage of the refrigerant in the reheater 3 is eliminated. In addition, after the 2 nd expansion valve 9 is set to the minimum opening degree, the controller 50 sets the 2 nd expansion valve 9 to the fully closed state when the adjustment reference time has elapsed while the degree of supercooling by the reheater 3 is maintained in a state not to be converged within the storage reference range. Therefore, it is possible to avoid a situation in which the instructed operation is not started for a long period of time, and therefore it is possible to prevent a reduction in user comfort.

When the degree of supercooling by the reheater 3 is larger than the upper limit value of the appropriate range of the refrigerant amount, the controller 50 determines whether the outside temperature is lower than the condensation temperature. When the external liquid temperature is lower than the condensation temperature, the controller 50 opens the cooling on-off valve 6. Therefore, the refrigerant can be discharged from the main circuit 31 including the reheater 3 in which the refrigerant becomes excessive to the outdoor heat exchanger 7. Therefore, the refrigerant distributed to the reheater 3 can be adjusted to an optimum amount, and therefore the efficiency of the dehumidification operation can be improved.

When the condition that the degree of supercooling by the reheater 3 is within the storage reference range is satisfied during a period from when the cooling on-off valve 6 is opened until the opening/closing reference time elapses, the controller 50 closes the cooling on-off valve 6. Therefore, the instructed operation can be started quickly at a timing when the excess of the refrigerant in the reheater 3 is eliminated. In addition, after the cooling on-off valve 6 is opened, the controller 50 closes the cooling on-off valve 6 when the open/close reference time has elapsed while the degree of supercooling by the reheater 3 remains within the storage reference range. Therefore, it is possible to avoid a situation in which the instructed operation is not started for a long period of time, and therefore it is possible to prevent a reduction in user comfort.

In the air-conditioning apparatus 100 according to embodiment 1, when the external liquid SC during the cooling operation is outside the appropriate range of the refrigerant quantity, the controller 50 controls the reheat on-off valve 2 or the 1 st expansion valve 4 based on the result of determination using the internal liquid temperature. Therefore, since the amount of refrigerant in the outdoor heat exchanger 7 can be adjusted according to the outside temperature, the uneven distribution of refrigerant in the refrigerant circuit 30 can be suppressed, and the operating efficiency can be improved.

When the degree of supercooling by the condenser is smaller than the lower limit value of the appropriate refrigerant amount range, the control device 50 determines whether both the outdoor high-pressure protection condition and the indoor refrigerant discharge condition are satisfied, and when both the outdoor high-pressure protection condition and the indoor refrigerant discharge condition are satisfied, the 1 st expansion valve 4 is set to the minimum opening degree for a predetermined period. Therefore, the refrigerant accumulated in the reheater 3 can be circulated, and therefore, the shortage of refrigerant in the outdoor heat exchanger 7 can be eliminated.

When the condition that the degree of subcooling by the condenser is within the storage reference range is satisfied during a period from when the 1 st expansion valve 4 is set to the minimum opening degree until the adjustment reference time elapses, the control device 50 sets the 1 st expansion valve 4 to the fully closed state. Therefore, the operation can be resumed promptly at a timing at which the shortage of the refrigerant in the outdoor heat exchanger 7 is eliminated. In addition, after the 1 st expansion valve 4 is set to the minimum opening degree, the controller 50 sets the 1 st expansion valve 4 to the fully closed state when the adjustment reference time has elapsed while the degree of subcooling by the condenser is maintained so as not to fall within the storage reference range. Therefore, since it is possible to avoid a situation in which the operation is not restarted for a long period of time, it is possible to prevent a reduction in user comfort.

Further, if the degree of supercooling by the condenser is larger than the upper limit value of the appropriate range of the refrigerant amount, the control device 50 determines whether or not the inner liquid temperature is smaller than the condensation temperature. Then, if the internal liquid temperature is lower than the condensation temperature, the controller 50 opens the reheat opening/closing valve 2. Therefore, since the amount of refrigerant flowing into the outdoor heat exchanger 7 in which the amount of refrigerant becomes excessive can be reduced, the amount of refrigerant distributed in the outdoor heat exchanger 7 can be adjusted to an optimum amount, and the efficiency of the cooling operation can be improved.

When the condition that the degree of subcooling by the condenser is within the storage reference range is satisfied during a period from when the reheat on-off valve 2 is opened until the opening/closing reference time elapses, the control device 50 closes the reheat on-off valve 2. Therefore, the operation can be resumed promptly at a timing when the excess refrigerant in the outdoor heat exchanger 7 is eliminated. In addition, after the reheat on-off valve 2 is opened, the controller 50 closes the reheat on-off valve 2 when the open/close reference time has elapsed while the degree of subcooling by the condenser is maintained within the storage reference range. Therefore, since it is possible to avoid a situation in which the operation is not restarted for a long period of time, it is possible to prevent a reduction in user comfort.

That is, the air-conditioning apparatus 100 adjusts the refrigerant amount to be appropriate by the operation switching control and the refrigerant distribution control described above. Therefore, during the dehumidification operation, the amount of reheating of the reheater 3 required during the dehumidification operation can be secured, and the sufficient dehumidification capability can be exhibited. In addition, during the cooling operation, the condensation amount of the outdoor heat exchanger 7 required during the cooling operation can be secured to exhibit a sufficient cooling capacity.

The control device 50 has the following functions: when the compressor 1 is started and the operation mode is switched, the refrigerant equalization process is performed for a predetermined period after the cooling on-off valve 6 and the reheat on-off valve 2 are closed. In the refrigerant averaging process, the control device 50 controls the opening degree of the 2 nd expansion valve 9 so that the degree of subcooling by the condenser falls within the appropriate range for the condenser, and controls the opening degree of the 1 st expansion valve 4 so that the degree of superheat by the evaporator falls within the refrigerant adjustment range. Therefore, the refrigerant distribution in the refrigerant circuit 30 can be rationalized.

In the refrigerant leveling process, when the leveling conditions that the degree of subcooling by the condenser is within the appropriate range of the condenser and the degree of superheat by the evaporator is within the refrigerant adjustment range are satisfied within a set time period after the cooling on-off valve 6 and the reheat on-off valve 2 are closed, the control device 50 starts the instructed operation. Therefore, the instructed operation can be started quickly at the timing when the refrigerant in the refrigerant circuit 30 is averaged. In addition, in the refrigerant averaging process, when the averaging condition is not satisfied within the set time, the control device 50 starts the instructed operation when the set time elapses. Therefore, it is possible to avoid a situation in which the instructed operation is not started for a long period of time, and therefore it is possible to prevent a reduction in user comfort.

However, if only the 2 nd expansion valve 9 is controlled to ensure the degree of supercooling by the condenser within the appropriate range of the condenser, there is a possibility that liquid return may occur. This is because the control of only the 2 nd expansion valve 9 cannot reduce the extra refrigerant. In this regard, as described above, the control device 50 executes the SH control of the 1 st expansion valve 4 for ensuring the degree of heating by the evaporator within the refrigerant adjustment range, in addition to the SC control of the 2 nd expansion valve 9. Accordingly, excess refrigerant can be stored in the receiver 8, and circulating refrigerant can be stored in the outdoor heat exchanger 7, so that occurrence of liquid return can be suppressed. That is, the air-conditioning apparatus 100 according to embodiment 1 can prevent the compressor 1 from being damaged by the returned liquid while suppressing the decrease in the reheating capacity by the combination of the SC control of the 2 nd expansion valve 9 and the SH control of the 1 st expansion valve 4.

In the air-conditioning apparatus 100 according to embodiment 1, since the control unit 50 closes the cooling on-off valve 6 during the dehumidification operation, stagnation of the refrigerant in the outdoor heat exchanger 7 can be prevented, and thus the dehumidification performance can be prevented from being lowered, and the dehumidification operation can be performed efficiently. In the dehumidification operation, the controller 50 may set the 2 nd expansion valve 9 to be fully closed. Thus, since the refrigerant can be prevented from flowing into the main circuit 31 from the cooling circuit 32, the operation efficiency of the dehumidification operation can be improved.

The main circuit 31 has a reheat on-off valve 2 that is opened and closed between the reheater 3 and a portion of the main pipe 21 between the compressor 1 and the reheater 3 that is connected to the cooling pipe 22. During the cooling operation, controller 50 closes reheat opening/closing valve 2. Therefore, since the inflow of the refrigerant into the reheater 3 can be prevented, the refrigerant cycle during the cooling operation can be smoothed and the operation efficiency can be improved. In addition, the controller 50 may set the 1 st expansion valve 4 in a fully closed state during the cooling operation. In this way, the refrigerant staying in the flow path from the 1 st connection unit M to the reheater 3 and the 1 st expansion valve 4 to the 2 nd connection unit N can be prevented from flowing into the indoor heat exchanger 5, and therefore the operation efficiency during the cooling operation can be further improved.

When the indoor refrigerant leakage sensor 41 detects refrigerant leakage, the controller 50 closes the reheat on-off valve 2 and completely closes the 2 nd 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 receiver 8, so that leakage of the refrigerant into the room can be suppressed. In addition, when the leakage of the refrigerant is detected by the indoor refrigerant leakage sensor 41, the control device 50 may set the 1 st expansion valve 4 in the fully closed state. Thus, since the refrigerant accumulated in the reheater 3 and the like can be prevented from flowing into the indoor heat exchanger 5, the refrigerant leakage into the room can be reduced when the refrigerant leakage point is not located on the flow path from the reheat opening/closing valve 2 to the 1 st expansion valve 4 via the reheater 3. Further, by setting the reheat opening/closing valve 2 and the defrost opening/closing valve 10 in the closed state and setting the 1 st expansion valve 4 in the fully closed state, the refrigerant circuits from the reheat opening/closing valve 2 to the 1 st expansion valve 4 are made independent, whereby the determination of the refrigerant leakage portion can be facilitated.

When the leakage of the refrigerant is detected by the outdoor-refrigerant leakage sensor 42, the control device 50 closes the cooling opening/closing valve 6 and completely closes the 1 st expansion valve 4. This can cut off the flow of the refrigerant to the outside of the room, and can accumulate the refrigerant outside the room in the indoor heat exchanger 5, thereby suppressing leakage of the refrigerant outside the room. In addition, when the outdoor refrigerant leakage sensor 42 detects the leakage of the refrigerant, the control device 50 may set the 2 nd expansion valve 9 to the fully closed state. In this way, the refrigerant circuits from the cooling on-off valve 6 to the 2 nd expansion valve 9 can be made independent, and the location of refrigerant leakage can be quickly identified.

However, when the operation switching control and the refrigerant distribution control are not performed, the refrigerant tends to flow to the side where the temperature is low, such as the indoor side or the outdoor side. That is, if the operation switching control and the refrigerant distribution control are not performed, the refrigerant easily flows into the reheater 3 when the indoor temperature is lower than the outdoor temperature, and therefore the indoor temperature is higher than the desired temperature and the relative humidity is lower than the desired humidity. On the other hand, when the outdoor temperature is lower than the indoor temperature, the refrigerant is less likely to flow to the reheater 3, and therefore the indoor temperature is lower than the desired target temperature, and the relative humidity is higher than the desired humidity. In this regard, the control device 50 can adjust the refrigerant distribution to an appropriate amount as described above. Therefore, the indoor unit 70 can exhibit dehumidification capability while ensuring the amount of heating by the reheater 3.

Embodiment 2.

The air-conditioning apparatus according to embodiment 2 is configured to reduce variations in the outlet air temperature. The configuration of the air-conditioning apparatus according to embodiment 2 is the same as the configuration illustrated in fig. 1 and 2. Therefore, the same reference numerals are used for the constituent members equivalent to those of embodiment 1, and the description thereof is omitted.

Fig. 11 is an explanatory diagram illustrating a specific configuration of the indoor heat exchanger according to embodiment 2 of the present invention. As shown in fig. 11, the indoor heat exchanger 5 is a plate-fin heat exchanger including a plurality of heat transfer tubes 13, a plurality of fins 14, a refrigerant distributor 15, and a header 16. The reheater 3 of embodiment 2 is a plate-fin heat exchanger having the same configuration as the indoor heat exchanger 5. That is, the reheater 3 is composed of a plurality of heat transfer pipes 13, a plurality of fins 14, a refrigerant distributor 15, and a header 16. In fig. 11, the number of heat transfer pipes 13, the number of fins 14, the number of layers, and the number of rows are merely examples. That is, the number of heat transfer tubes 13, the number of fins 14, the number of layers, and the number of rows can be changed as appropriate for each of the indoor heat exchanger 5 and the reheater 3.

[ characteristics of non-azeotropic refrigerant mixture ]

An air-conditioning apparatus may use a non-azeotropic refrigerant mixture in which a plurality of refrigerants are mixed as a refrigerant circulating in a refrigerant circuit. The non-azeotropic refrigerant mixture changes in temperature due to phase change at the same pressure. Therefore, for example, in the case where a non-azeotropic mixture refrigerant passes through the evaporator, the temperature on the upstream side is lower than the temperature on the downstream side during evaporation. In addition, in the case where the non-azeotropic refrigerant mixture passes through the condenser, the temperature on the upstream side is higher than the temperature on the downstream side during the condensation.

Fig. 12 is an explanatory view illustrating a mollier diagram of a zeotropic refrigerant mixture. Fig. 13 is a mollier chart showing a specific example of the temperature gradient of the zeotropic refrigerant mixture. In fig. 12, the isotherm of the azeotropic refrigerant mixture is shown by a solid line, and the isotherm of the zeotropic refrigerant mixture is shown by a broken line between the saturated liquid line and the saturated vapor line. That is, when a non-azeotropic refrigerant mixture is used, a temperature gradient occurs between the inlet and the outlet of the heat exchanger in the evaporation step and the condensation step, which change at a constant pressure.

Fig. 13 illustrates a case where the temperature gradient between the inlet and the outlet of the indoor heat exchanger 5 in the low temperature region of the zeotropic refrigerant mixture is about 5 ℃. In this example, the refrigerant temperature on the inlet side of the indoor heat exchanger 5 is-12 ℃ and the refrigerant temperature on the outlet side is-7 ℃. That is, in the indoor heat exchanger 5, the refrigerant temperature on the inlet side is lower than the refrigerant temperature on the outlet side. Therefore, a difference in the blowing temperature occurs between the inlet and the outlet of the indoor heat exchanger 5.

When a refrigerant having a temperature gradient such as a non-azeotropic refrigerant is used, the cooling of air is promoted and the blowing temperature is lowered on the inlet side of the evaporator where the temperature of the refrigerant is low, and the blowing temperature is raised on the outlet side of the evaporator where the temperature of the refrigerant is high. That is, the temperature of the air blown out from the heat exchanger varies. In addition, in a heat pump type air conditioning apparatus capable of realizing reheat dehumidification, fluctuations occur in the stability of the temperature and humidity of the air-conditioned space due to variations in the outlet air temperature.

Especially in the presence of CO ₂ In the refrigerant of (2), since the temperature gradient becomes large, the variation in the blowing temperature becomes remarkable. Comprising CO ₂ The non-azeotropic refrigerant of (2) is, for example, R32, R125, R134a, R1234yf, and CO ₂ The mixed refrigerant of (1). For the non-azeotropic refrigerant mixture of this example, the composition of R32 is 49 to 55wt%, the composition of R125 is 16 to 22wt%, the composition of R134a is 7 to 13wt%, the composition of R1234yf is 6 to 12wt%, CO ₂ The composition of (A) is 7wt% -13 wt%. R32, R125, R134a, R1234yf and CO ₂ The composition ratio of (B) is 100wt% in total.

Here, the flow of the refrigerant in the indoor heat exchanger 5 will be described. First, the low-temperature, low-pressure refrigerant in a liquid state decompressed and expanded by the 1 st expansion valve 4 flows into the indoor heat exchanger 5 from the inlet of the refrigerant distributor 15. The refrigerant flowing in from the inlet of the refrigerant distributor 15 is distributed by the refrigerant distributor 15, and flows from the outlets of the refrigerant distributor 15 to the plurality of heat transfer tubes 13. The refrigerant flowing into the heat transfer pipe 13 flows in the axial direction of the heat transfer pipe 13. The indoor air blower 11 blows indoor air, which is a cooling target, to the surfaces of the heat conducting pipes 13 and the fins 14. In the air-conditioning apparatus 100 according to embodiment 2, the air blown by the indoor air-sending device 11 to the indoor heat exchanger 5 flows in the direction opposite to the refrigerant flowing through the heat transfer tubes 13. The air-conditioning apparatus 100 reduces heat exchange loss by fluidizing air to be blown to the indoor heat exchanger 5 and the refrigerant flowing through the heat transfer pipe 13 in opposite directions, thereby improving the performance of the indoor heat exchanger 5. The refrigerant flowing through heat transfer pipe 13 exchanges heat with indoor air in contact with heat transfer pipe 13 and fins 14, and absorbs heat of the indoor air. The refrigerant that has exchanged heat with the indoor air at the heat transfer tubes 13 flows in from the inlet of the header 16, merges in the header 16, and flows toward the compressor 1 from the outlet of the header 16.

Next, the flow of the refrigerant in the reheater 3 will be described. First, the high-temperature, high-pressure gas refrigerant heated and compressed by the compressor 1 flows in from the inlet of the refrigerant distributor 15. The refrigerant flowing from the inlet of the refrigerant distributor 15 is distributed by the refrigerant distributor 15, and flows from the respective outlets of the refrigerant distributor 15 to the plurality of heat transfer tubes 13. The refrigerant flowing into the heat transfer pipe 13 flows in the axial direction of the heat transfer pipe 13. The air cooled by the indoor heat exchanger 5 is blown to the surfaces of the heat guide pipes 13 and the fins 14. In the air-conditioning apparatus 100 according to embodiment 2, the air blown to the reheater 3 flows in a direction opposite to the direction of the refrigerant flowing through the heat transfer tubes 13. The air-conditioning apparatus 100 reduces heat exchange loss by fluidizing air blown to the reheater 3 in opposite directions to the refrigerant flowing through the heat transfer tubes 13, thereby improving the performance of the reheater 3. The refrigerant flowing through the heat transfer tubes 13 is cooled by the indoor heat exchanger 5, exchanges heat with air in contact with the heat transfer tubes 13 and the fins 14, and radiates heat to the air. The refrigerant that has exchanged heat with the air at the heat transfer tubes 13 flows in from the inlet of the header 16, merges into the header 16, and flows from the outlet of the header 16 to the 1 st expansion valve 4.

When a non-azeotropic refrigerant mixture is used, in the indoor heat exchanger 5, a difference occurs in heat exchange capacity between the inlet side of the refrigerant distributor 15 and the outlet side of the header 16. Therefore, a temperature difference occurs between the air passing through the inlet side of the refrigerant distributor 15 and the air passing through the outlet side of the header 16. Similarly, in the reheater 3, a difference occurs in heat exchange capacity between the inlet side of the refrigerant distributor 15 and the outlet side of the header 16. However, in the reheater 3, the refrigerant temperature on the inlet side is higher than the refrigerant temperature on the outlet side, as opposed to the indoor heat exchanger 5.

Therefore, if the reheater 3 and the indoor heat exchanger 5 are arranged such that the inlet side of the indoor heat exchanger 5 faces the outlet side of the reheater 3 and the outlet side of the evaporator faces the inlet side of the reheater 3, the temperature difference generated in the indoor heat exchanger 5 further increases in the reheater 3. That is, with the arrangement as described above, the outlet air temperature at the time of reheating dehumidification varies depending on the location due to the temperature difference between the inlet and the outlet of the heat exchanger that occurs when the non-azeotropic refrigerant mixture is used.

In view of this, the air-conditioning apparatus 100 according to embodiment 2 arranges the indoor heat exchanger 5 and the reheater 3 such that the air having passed through the portion of the indoor heat exchanger 5 having the lowest refrigerant temperature passes through the portion of the reheater 3 having the highest refrigerant temperature. That is, the indoor heat exchanger 5 and the reheater 3 are arranged such that the air having passed through the portion of the indoor heat exchanger 5 having the highest refrigerant temperature passes through the portion of the reheater 3 having the lowest refrigerant temperature. In the air-conditioning apparatus 100 according to embodiment 2, the indoor heat exchanger 5 and the reheater 3 are provided on a common air path, as in embodiment 1.

Fig. 14 is an explanatory diagram showing an example of arrangement of the evaporator and the reheater in the air-conditioning apparatus according to embodiment 2 of the present invention. In fig. 14, the intervals between the wavy lines shown inside the indoor heat exchanger 5 and the reheater 3 correspond to the refrigerant temperature levels. That is, in fig. 14, the wavy lines are illustrated such that the refrigerant temperature increases when the interval between the wavy lines is narrow, and the refrigerant temperature decreases when the interval between the wavy lines is wide.

That is, in the indoor heat exchanger 5, the temperature on the refrigerant inlet side is lower than the temperature on the refrigerant outlet side. In the reheater 3, the temperature of the refrigerant on the inlet side is higher than the temperature of the refrigerant on the outlet side. The indoor heat exchanger 5 and the reheater 3 are arranged such that air having passed through the inlet side of the refrigerant in the indoor heat exchanger 5 passes through the outlet side of the refrigerant in the reheater 3, and air having passed through the outlet side of the refrigerant in the indoor heat exchanger 5 passes through the inlet side of the refrigerant in the reheater 3.

For example, as shown in fig. 14, a configuration may be adopted in which a portion of the indoor heat exchanger 5 having a relatively low refrigerant temperature faces a portion of the reheater 3 having a relatively high refrigerant temperature, and a portion of the indoor heat exchanger 5 having a relatively high refrigerant temperature faces a portion of the reheater 3 having a relatively low refrigerant temperature. The indoor heat exchanger 5 and the reheater 3 are both arranged so that the refrigerant flows from the upper portion to the lower portion. The specific arrangement of the indoor heat exchanger 5 and the reheater 3 may be selected as appropriate based on the blowing temperatures from the heat exchangers due to the arrangement of the respective devices and the path pattern.

However, fig. 14 illustrates a case where the number of rows of the heat exchangers is 1 row, but the present invention is not limited thereto, and the number of rows of the heat exchangers may be 2 rows or more. When the number of rows of at least 1 of the indoor heat exchanger 5 and the reheater 3 is 2 or more, the arrangement of the indoor heat exchanger 5 and the reheater 3 may be determined based on the heat distribution of each heat exchanger.

Fig. 15 is a table showing states of each opening/closing valve and each expansion valve when refrigerant leaks in the air-conditioning apparatus according to embodiment 2 of the present invention. The control device 50 according to embodiment 2 acquires the leakage signals from each of the indoor refrigerant leakage sensor 41 and the outdoor refrigerant leakage sensor 42, as in the case of embodiment 1.

When a refrigerant leak is detected on the indoor side, the controller 50 closes the indoor reheat opening/closing valve 2 and fully opens the 1 st expansion valve 4 on the downstream side of the reheater 3. This allows the refrigerant existing in the flow path from the 1 st connection unit M to the 2 nd connection unit N via the reheater 3 and the 1 st expansion valve 4 to be guided to the indoor heat exchanger 5. When the refrigerant leakage is detected on the indoor side, the control device 50 completely closes the 2 nd expansion valve 9 on the downstream side of the outdoor heat exchanger 7 by opening the cooling opening/closing valve 6 on the outdoor side. By controlling these valves, the refrigerant can be stored outside the room. Therefore, when the refrigerant leaks into the room, the filling of the room with the inert gas can be suppressed, and safety can be improved.

When a refrigerant leak is detected on the outdoor side, the control device 50 closes the cooling on-off valve 6 and fully opens the 2 nd expansion valve 9. This allows the refrigerant present in the cooling circuit 32 to be guided to the indoor heat exchanger 5. When refrigerant leakage is detected on the outdoor side, the control device 50 opens the reheat opening/closing valve 2 and completely closes the 1 st expansion valve 4. By controlling these valves, refrigerant can be stored in the indoor side. Therefore, when the refrigerant leaks outdoors, filling of the inert gas outdoors can be suppressed, and safety can be improved.

In embodiment 2, the refrigerant circuit 30 is controlled by the control device 50 using the dryness by utilizing the characteristics of the zeotropic refrigerant mixture. However, since the conventional pseudo-azeotropic refrigerant does not have a temperature gradient of the two-phase refrigerant, the dryness cannot be calculated when the pseudo-azeotropic refrigerant is used. Therefore, the refrigerant circuit is generally controlled using the degree of superheat and the degree of subcooling calculated from the saturation temperature and the refrigerant temperature of the high pressure and the low pressure, and since the state of the refrigerant is unclear, a method of controlling the calculated degree of superheat and the calculated degree of subcooling with likelihood has been conventionally employed.

In this regard, in the non-azeotropic refrigerant mixture, since the dryness can be obtained from the pressure and the temperature, and the state of the refrigerant can be known from the obtained dryness, it is possible to construct a highly reliable control without performing a design with likelihood. That is, when a non-azeotropic refrigerant mixture is used, control along the saturation line on the mollier diagram can be realized, and therefore control that effectively utilizes the capacity of the heat exchanger can be constructed. This is because the zeotropic refrigerant mixture has a temperature gradient of the two-phase refrigerant.

The air-conditioning apparatus 100 according to embodiment 2 may be configured by providing a low-pressure sensor that measures the pressure on the suction side of the compressor 1 and an evaporator temperature sensor that measures the temperature at a position where the dryness of the indoor heat exchanger 5 (the dryness on the low-pressure side) is obtained. Then, the control device 50 can determine the dryness on the low pressure side from the pressure detected by the low pressure sensor and the temperature detected by the evaporator temperature sensor. In the non-azeotropic refrigerant, the dryness of the low-pressure side is uniquely determined from the pressure and the temperature of the refrigerant. Here, the low pressure sensor corresponds to the pressure sensor 61 of fig. 1, and the evaporator temperature sensor corresponds to the refrigerant temperature sensor 68 of fig. 1. Further, the condenser may be provided with a high-pressure sensor for measuring the pressure on the discharge side of the compressor 1 and a condenser temperature sensor for measuring the temperature at a position where the dryness (dryness on the high-pressure side) of the reheater 3 or the outdoor heat exchanger 7 is obtained. Then, the control device 50 can determine the dryness on the high pressure side from the pressure detected by the high pressure sensor and the temperature detected by the condenser temperature sensor. In the non-azeotropic refrigerant, the dryness on the high pressure side is uniquely determined from the pressure and the temperature of the refrigerant. Here, the high pressure sensors correspond to the pressure sensors 62, 63, 64 of fig. 1, and the condenser temperature sensors correspond to the refrigerant temperature sensors 67, 69 of fig. 1. The dryness of the reheater 3 is determined from the pressure measured by the pressure sensor 62 or 63 and the temperature measured by the refrigerant temperature sensor 67. The dryness of the outdoor heat exchanger 7 is determined from the pressure measured by the pressure sensor 62 or the pressure sensor 64 and the temperature measured by the refrigerant temperature sensor 69.

As described above, the air-conditioning apparatus 100 according to embodiment 2 can also prevent a decrease in dehumidification capability and perform the dehumidification operation efficiently. In embodiment 2, the indoor heat exchanger 5 and the reheater 3 are arranged such that the position where the outlet temperature of the indoor heat exchanger 5 becomes low and the position where the outlet temperature of the reheater 3 becomes high overlap in the flow of air. That is, the air-conditioning apparatus 100 is configured such that the portion of the indoor heat exchanger 5 having the lowest refrigerant temperature and the portion of the reheater 3 having the highest refrigerant temperature overlap with respect to the common air passage based on the temperature distributions of the indoor heat exchanger 5 and the reheater 3. Therefore, air with little temperature variation can be supplied to the room during the dehumidification operation or the intermediate operation.

More specifically, the refrigerant circuit 30 according to embodiment 2 uses a non-azeotropic refrigerant mixture as a refrigerant circulating therein. Therefore, with the indoor heat exchanger 5, the temperature on the refrigerant inlet side is lower than the temperature on the refrigerant outlet side. In addition, in the reheater 3, the temperature of the refrigerant on the inlet side is higher than the temperature of the refrigerant on the outlet side. The indoor heat exchanger 5 and the reheater 3 are arranged such that air having passed through the inlet side of the refrigerant in the indoor heat exchanger 5 passes through the inlet side of the refrigerant in the reheater 3, and air having passed through the outlet side of the refrigerant in the indoor heat exchanger 5 passes through the outlet side of the refrigerant in the reheater 3. For example, paths of the refrigerant flowing to the indoor heat exchanger 5 and the reheater 3 may be defined as shown in fig. 14. Therefore, since variations in the outlet air temperature and fluctuations in humidity due to variations in the outlet air temperature can be reduced, variations in the temperature 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. Other effects and the like are the same as those of embodiment 1.

Embodiment 3.

Fig. 16 is a configuration diagram of the entire air-conditioning apparatus according to embodiment 3 of the present invention. The air-conditioning apparatus 200 according to embodiment 3 is different in part from the air-conditioning apparatus 100 according to embodiments 1 and 2 in the configuration of the refrigerant circuit 30. The same reference numerals are used for the same components as those in embodiments 1 and 2, and the description thereof is omitted.

As shown in fig. 16, the refrigerant circuit 30 according to embodiment 3 is different from embodiment 1 in that the receiver 8 is not mounted and the accumulator 18 is mounted, and the other configuration is the same as embodiment 1. The air conditioning unit 200 is capable of retaining refrigerant in the accumulator 18 during transient liquid returns, which further reduces the risk of damage to the compressor.

In embodiment 3, by executing the operation switching control and the refrigerant distribution control described in embodiment 1, the operation of the optimal amount of refrigerant in each of the reheater 3 and the outdoor heat exchanger 7 can be realized. Therefore, the capacity of the air-conditioning apparatus 200 can be maintained to be appropriate, and excess refrigerant generated in a transient manner can be stored in the inexpensive accumulator 18. That is, even if the refrigerant returns to the compressor 1 due to the liquid return, the liquid compression in the compressor 1 can be suppressed by the action of the accumulator 18, so that the air-conditioning apparatus 200 with high reliability can be provided.

As described above, the degree of supercooling by the reheater 3, that is, the internal liquid SC can be obtained from the high-pressure obtained from the pressure sensor 62 and the internal liquid temperature obtained from the refrigerant temperature sensor 67. That is, the controller 50 calculates the condensation temperature by performing saturation conversion on the high pressure, and can calculate the internal liquid SC by subtracting the internal liquid temperature from the condensation temperature. As described above, the degree of supercooling by the outdoor heat exchanger 7, that is, the external liquid SC can be obtained from the condenser outlet pressure obtained from the pressure sensor 64 and the outdoor heat exchanger outlet temperature obtained from the refrigerant temperature sensor 69. That is, the controller 50 calculates the condensing temperature CT by performing saturation conversion on the condenser outlet pressure, and can calculate the degree of supercooling of the outlet of the outdoor heat exchanger 7, that is, the external liquid SC, by subtracting the external liquid temperature from the condensing temperature CT. When the external liquid SC is obtained, the control device 50 may obtain the condensation temperature CT using the high-pressure obtained from the pressure sensor 62 instead of the condenser outlet pressure obtained from the pressure sensor 64.

The control of the on-off valves and the expansion valves when the refrigerant leaks indoors and outdoors is the same as in embodiments 1 and 2 described above. The air-conditioning apparatus 200 may be configured to apply the arrangement of the reheater 3 and the indoor heat exchanger 5 in embodiment 2 described above, or may control the refrigerant circuit 30 using the dryness as in the case of embodiment 2.

As described above, the air-conditioning apparatus 200 according to embodiment 3 can also prevent a decrease in dehumidification capability and perform the dehumidification operation efficiently. However, in the refrigerant circuit 30 including the receiver 8 as in embodiment 1, the 2 nd expansion valve 9 needs to be operated to secure a superheat degree for protection against the return liquid. Therefore, an expensive high-pressure vessel such as the reservoir 8 having a large capacity is required to store the excessive refrigerant.

In this regard, in the air-conditioning apparatus 200 according to embodiment 3, even if the refrigerant returns to the compressor 1 due to the liquid return, the liquid compression of the compressor 1 can be suppressed by the action of the accumulator 18 without using the liquid receiver. Therefore, the reliability of the air-conditioning apparatus can be improved.

The air-conditioning apparatus 200 separates the non-azeotropic refrigerant mixture into gas and liquid by the accumulator 18, accumulates the high-boiling-point refrigerant in the accumulator 18, and increases the heat capacity during the defrosting operation by using the low-boiling-point refrigerant. That is, in the defrosting operation, the air-conditioning apparatus 200 accumulates the high-boiling-point refrigerant included in the zeotropic refrigerant mixture in the accumulator 18, and circulates the low-boiling-point refrigerant included in the zeotropic refrigerant mixture in the refrigerant circuit 30. Therefore, the defrosting time can be shortened. Other effects and the like are the same as those of embodiments 1 and 2.

The above-described embodiments are preferable specific examples of the air-conditioning apparatus, and the technical scope of the present invention is not limited to these embodiments. For example, although the control device 50 performs both the operation switching control and the refrigerant distribution control in the above description, the present invention is not limited to this, and the control device 50 may not have a function of performing the operation switching control. The control device 50 may be configured to perform the refrigerant distribution control only in either the dehumidification operation or the cooling operation.

Further, the air-conditioning apparatus 100 may not have a function of performing the cooling operation and the defrosting operation, and in this case, the reheat opening/closing valve 2 is not required. Therefore, the main circuit 31 is configured by sequentially connecting the compressor 1, the reheater 3, the 1 st expansion valve 4, and the indoor heat exchanger 5 by the main pipe 21. In embodiments 1 and 2, the example in which the receiver 8 is provided in the refrigerant circuit 30 is illustrated, but the present invention is not limited to this, and the refrigerant circuit 30 of embodiments 1 and 2 may not have the receiver 8. In the above embodiments, the case where the main circuit 31 is disposed in the air-conditioned space has been exemplified, but the present invention is not limited to this, and at least the reheater 3 and the indoor heat exchanger 5 in the configuration of the main circuit 31 may be disposed in the air-conditioned space. In addition, the refrigerant circuit 30 according to embodiments 1 to 3 may not have the bypass circuit 33. However, if the bypass circuit 33 is not provided in the refrigerant circuit 30, the defrosting operation in the flow path as in embodiment 1 cannot be realized.

In the above embodiments, the case where the main circuit 31 is disposed in the air-conditioned space has been exemplified, but the present invention is not limited to this, and at least the reheater 3 and the indoor heat exchanger 5 may be disposed in the air-conditioned space. In fig. 1 and 16, an example is shown in which the indoor refrigerant leakage sensor 41 is provided inside the indoor unit 70, but the present invention is not limited to this, and the indoor refrigerant leakage sensor 41 may be provided inside the air-conditioned space and outside the indoor unit 70. Similarly, although fig. 1 and 16 show an example in which the outdoor refrigerant leakage sensor 42 is provided inside the outdoor unit 80, the present invention is not limited thereto, and the outdoor refrigerant leakage sensor 42 may be provided outside the air-conditioned space and the outdoor unit 80.

Although fig. 1 and 16 show an example in which the control device 50 is provided inside the indoor unit 70, the present invention is not limited to this, and the control device 50 may be provided inside the outdoor unit 80. The outdoor unit 80 may be provided with an outdoor control device that controls the operation of each actuator of the outdoor unit 80 such as the outdoor fan 12, and the control device 50 may control the air- conditioning apparatus 100 or 200 in cooperation with the outdoor control device. In addition, the processing of the opening/closing valves and the expansion valves in the refrigerant leakage illustrated in fig. 15 can be applied to the configurations of embodiments 1 and 3.

Description of reference numerals:

1 … compressor; 1a … compressor motor; 2 … reheat opening and closing valve; 3 … reheater; 4 … expansion valve 1; 5 … indoor heat exchanger (evaporator); 6 … cooling on-off valve; 7 … outdoor heat exchanger (condenser); 8 … liquid storage part; 9 … expansion valve No. 2; 10 … defrosting on-off valve; 11 … indoor blower; 11a, 12a … fan motor; 12 … outdoor blower; 13 … heat pipes; 14 … fin; 15 … refrigerant distributor; a 16 … header; 18 … accumulator; 20 … refrigerant piping; 21 … main piping; 22 … cooling tubing; 23 … bypass tubing; a 30 … refrigerant circuit; 31 … main loop; 32 … cooling loop; 33 … bypass loop; 41 … indoor refrigerant leakage sensor; 42 … outdoor refrigerant leakage sensor; 45 … exception reporter; 50 … control device; 51 … operation processing section; 51a … setting processing section; 51b …;51c … excess refrigerant detector; 51d … leakage treatment section; 52 … storage section; 61-64 … pressure sensor; 65-69 … refrigerant temperature sensor; 70 … indoor unit; 80 … outdoor unit; 91. 92 … air temperature sensor; 100. 200 … air conditioning apparatus; CT … condensation temperature; CTmax … protects the condensation temperature; ET … evaporation temperature; m …, connection 1; n … connection 2; x, P, Y, Z … decision value; a to h, alpha, beta, gamma, delta … coefficients.

Claims (27)

1. An air conditioning device, comprising:

a refrigerant circuit including a main circuit in which a compressor, a reheater, a 1 st expansion valve, and an evaporator are sequentially connected by a main pipe, and a cooling circuit in which a cooling opening/closing valve, a condenser, and a 2 nd expansion valve are connected by a cooling pipe, the refrigerant circuit circulating a refrigerant, the cooling pipe connecting between the compressor and the reheater and between the 1 st expansion valve and the evaporator; and

a control device that controls the refrigerant circuit,

the reheater and the evaporator are disposed in an air-conditioned space,

the condenser is disposed outside the conditioned space,

in the dehumidification operation for dehumidifying the air in the air-conditioned space, if the degree of supercooling by the reheater is outside the appropriate range of the amount of refrigerant indicating that the amount of refrigerant distributed to the reheater is appropriate, the control device controls the cooling on-off valve or the 2 nd expansion valve based on a result of determination using an external liquid temperature, which is the temperature of the refrigerant flowing out of the condenser.

2. The air conditioning unit of claim 1,

if the degree of supercooling by the reheater is less than the lower limit value of the appropriate range of the refrigerant amount, the control device determines whether or not both an indoor high-pressure protection condition and an outdoor refrigerant discharge condition are satisfied, the indoor high-pressure protection condition being a condition that the condensing temperature is less than a determination threshold value for avoiding high-pressure abnormality, the outdoor refrigerant discharge condition being a condition that the external liquid temperature is higher than the evaporating temperature,

when both of the indoor high-pressure protection condition and the outdoor refrigerant discharge condition are satisfied, the control device sets the 2 nd expansion valve to a minimum opening degree for a predetermined period of time.

3. The air conditioning unit of claim 2,

the control device may be configured to set the 2 nd expansion valve in a fully closed state when a condition that a degree of supercooling by the reheater is within a storage reference range corresponding to an appropriate amount of refrigerant stored in the reheater is satisfied during a period from when the 2 nd expansion valve is set to a minimum opening degree until when an adjustment reference time elapses.

4. Air-conditioning unit according to claim 3,

after the 2 nd expansion valve is set to the minimum opening degree, the control device sets the 2 nd expansion valve to the fully closed state when the adjustment reference time has elapsed while the degree of supercooling by the reheater is maintained in a state of not converging within the storage reference range.

5. The air-conditioning apparatus according to any one of claims 1 to 4,

if the degree of supercooling by the reheater is larger than the upper limit value of the proper range of the refrigerant amount, the control device determines whether the temperature of the external liquid is lower than the condensing temperature,

the control device may set the cooling on-off valve to an open state if the external liquid temperature is lower than the condensation temperature.

6. The air conditioning unit of claim 5,

the control device may be configured to set the cooling on-off valve to a closed state when a condition that a degree of supercooling by the reheater is within a storage reference range corresponding to an appropriate amount of refrigerant stored in the reheater is satisfied during a period from when the cooling on-off valve is set to an open state until an open/close reference time elapses.

7. The air conditioning unit of claim 6,

the control device may be configured to set the cooling on-off valve to a closed state when the opening/closing reference time has elapsed after the cooling on-off valve is set to the open state, while maintaining the degree of supercooling by the reheater so as not to fall within the storage reference range.

8. An air conditioning device, comprising:

a refrigerant circuit including a main circuit in which a compressor, a reheater, a 1 st expansion valve, and an evaporator are sequentially connected by a main pipe, and a cooling circuit in which a cooling opening/closing valve, a condenser, and a 2 nd expansion valve are connected by a cooling pipe, the refrigerant circuit circulating a refrigerant, the cooling pipe connecting between the compressor and the reheater and between the 1 st expansion valve and the evaporator; and

a control device that controls the refrigerant circuit,

the main circuit has a reheat on-off valve that is opened and closed between the reheater and a connection portion between the main pipe and the cooling pipe between the compressor and the reheater,

the reheater and the evaporator are disposed in an air-conditioned space,

the condenser is disposed outside the conditioned space,

in the cooling operation for cooling the air in the air-conditioned space, if the degree of supercooling by the condenser is out of the appropriate range of the amount of refrigerant indicating that the amount of refrigerant distributed to the condenser is appropriate, the controller controls the reheat opening/closing valve or the 1 st expansion valve based on a result of determination using the internal temperature that is the temperature of the refrigerant flowing out of the reheater.

9. The air conditioning unit of claim 8,

if the degree of supercooling by the condenser is smaller than the lower limit value of the appropriate range of the refrigerant amount, the control device determines whether both an outdoor high-pressure protection condition in which the condensing temperature is lower than a determination threshold value for avoiding high-pressure abnormality and an indoor refrigerant discharge condition in which the temperature of the internal liquid is higher than the evaporating temperature are satisfied,

when both of the outdoor high-pressure protection condition and the indoor refrigerant discharge condition are satisfied, the control device sets the 1 st expansion valve to a minimum opening degree for a predetermined period.

10. The air conditioning unit of claim 9,

the control device may be configured to set the 1 st expansion valve in a fully closed state when a condition that a degree of supercooling by the condenser is within a storage reference range corresponding to an appropriate amount of refrigerant stored in the reheater is satisfied during a period from when the 1 st expansion valve is set to a minimum opening degree until when an adjustment reference time elapses.

11. The air conditioning unit of claim 10,

the control device may set the 1 st expansion valve to a fully closed state when the adjustment reference time has elapsed after the 1 st expansion valve is set to the minimum opening degree and the degree of supercooling by the condenser is maintained in a state of not converging in the accumulation reference range.

12. The air-conditioning apparatus according to any one of claims 8 to 11,

if the degree of supercooling by the condenser is larger than the upper limit value of the proper range of the refrigerant amount, the control device determines whether the temperature of the internal liquid is smaller than the condensing temperature,

the control device opens the reheat on-off valve when the internal liquid temperature is lower than the condensation temperature.

13. Air-conditioning arrangement according to claim 12,

the control device may be configured to set the reheat on-off valve to a closed state when a condition that a degree of subcooling by the condenser is within a storage reference range corresponding to an appropriate amount of refrigerant stored in the reheater is satisfied during a period from when the reheat on-off valve is set to an open state until an open/close reference time elapses.

14. The air conditioning unit of claim 13,

the control device may be configured to set the reheat on-off valve to a closed state when the open/close reference time has elapsed after the reheat on-off valve is set to the open state, while maintaining the degree of subcooling by the condenser within the storage reference range.

15. The air-conditioning apparatus according to any one of claims 1 to 4 and 6 to 11,

the main circuit has a reheat on-off valve that is opened and closed between the reheater and a connection portion between the main pipe and the cooling pipe between the compressor and the reheater,

the control device has: a function of executing a plurality of operation modes including a dehumidification operation of performing dehumidification of air in the air-conditioned space and a cooling operation of performing cooling of the air in the air-conditioned space; and a function of performing a refrigerant averaging process for averaging the refrigerant in the refrigerant circuit for a predetermined period of time after the cooling on-off valve and the reheat on-off valve are closed when the compressor is started and the operation mode is switched,

in the refrigerant averaging process, the opening degree of the 2 nd expansion valve is controlled so that the degree of subcooling by the condenser falls within a proper range of the condenser indicating that the amount of refrigerant in the condenser is appropriate, and the opening degree of the 1 st expansion valve is controlled so that the degree of superheat by the evaporator falls within a proper range of refrigerant adjustment indicating that the refrigerant distribution in the refrigerant circuit is appropriate.

16. The air conditioning unit of claim 15,

in the refrigerant averaging process, the control device starts the instructed operation when averaging conditions are satisfied in which the degree of subcooling by the condenser is within the appropriate range of the condenser and the degree of superheat by the evaporator is within the refrigerant adjustment range within a set time period after the cooling on-off valve and the reheat on-off valve are closed.

17. The air conditioning unit of claim 16,

in the refrigerant averaging process, the control device starts the instructed operation when the set time elapses, when the averaging condition is not satisfied within the set time.

18. The air-conditioning apparatus according to any one of claims 1 to 4, 6 to 11, 16, 17,

the control device sets the cooling on-off valve to a closed state during a dehumidification operation for dehumidifying air in the air-conditioned space.

19. The air conditioning unit of claim 18,

the control device sets the 2 nd expansion valve in a fully closed state during a dehumidification operation for dehumidifying air in the air-conditioned space.

20. The air conditioning unit of claim 18,

the main circuit has a reheat on-off valve that is opened and closed between the reheater and a portion of the main circuit between the compressor and the reheater that is connected to the main pipe and the cooling pipe,

the control device closes the reheat on-off valve during a cooling operation for cooling the air in the air-conditioned space.

21. The air conditioning unit of claim 20,

in the cooling operation, the controller may set the 1 st expansion valve to a fully closed state.

22. Air conditioning unit according to claim 20 or 21,

an indoor refrigerant leakage sensor disposed in the air-conditioned space and detecting leakage of refrigerant,

when the indoor refrigerant leakage sensor detects refrigerant leakage, the control device sets the reheat opening/closing valve to a closed state and sets the 2 nd expansion valve to a fully closed state.

23. The air conditioning unit of any one of claims 1 to 4, 6 to 11, 16, 17, 19, 21,

an outdoor refrigerant leakage sensor disposed outside the air-conditioned space and detecting leakage of refrigerant,

when the leakage of the refrigerant is detected by the outdoor refrigerant leakage sensor, the control device closes the cooling opening/closing valve and completely closes the 1 st expansion valve.

24. The air conditioning unit of any one of claims 1 to 4, 6 to 11, 16, 17, 19, 21,

the refrigerant circuit uses a non-azeotropic refrigerant mixture as a refrigerant circulating therein.

25. The air conditioning unit of claim 24,

the evaporator and the reheater are arranged such that air having passed through an inlet side of refrigerant in the evaporator passes through an inlet side of refrigerant in the reheater, and air having passed through an outlet side of refrigerant in the evaporator passes through an outlet side of refrigerant in the reheater.

26. The air conditioning unit of claim 25,

the evaporator and the reheater are each configured such that the refrigerant flows from an upper portion to a lower portion.

27. The air conditioning unit of claim 24,

the refrigerant circuit has:

the energy storage device is arranged between the compressor and the evaporator; and

and a bypass circuit including a bypass pipe connecting the compressor from a discharge side to a position between the reheater and the 1 st expansion valve, and a defrost on-off valve opening and closing the bypass pipe.

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