WO2023074621A1

WO2023074621A1 - Air conditioning device

Info

Publication number: WO2023074621A1
Application number: PCT/JP2022/039522
Authority: WO
Inventors: 聡乃守谷; 裕記藤岡; 裕伊藤
Original assignee: ダイキン工業株式会社
Priority date: 2021-10-26
Filing date: 2022-10-24
Publication date: 2023-05-04
Also published as: JP2023064264A; CN118159790A; JP7284421B2

Abstract

Provided is an air conditioning device that enables suitable control of the degree of opening of an electronic expansion valve in an indoor unit during a reheating dehumidification operation. An air conditioning device (1) comprises a refrigerant circuit (100) and a control unit (6). In the refrigerant circuit (100), there are a compressor (21), an outdoor heat exchanger (24), a first indoor heat exchanger (311), an indoor expansion valve (32), and a second indoor heat exchanger (312), which are connected in a ring. Controlling the refrigerant circuit (100), the control unit (6) executes a first operation for causing the outdoor heat exchanger (24) and the first indoor heat exchanger (311) to function as a condenser and causing the second indoor heat exchanger (312) to function as an evaporator. The indoor expansion valve (32) has a main valve body (322) and a sub valve body (323) for adjusting the degree of opening of the indoor expansion valve (32). The main valve body (322) has a greater flow rate control range than the flow rate control range of the sub valve body (323). When executing the first operation, the control unit (6) controls the indoor expansion valve (32) to adjust the degree of opening with the sub valve body (323) so that the refrigerant at the outlet of the second indoor heat exchanger (312) attains a wet state.

Description

air conditioner

"Regarding air conditioners."

An air conditioner is known that performs a reheat dehumidification operation in which dehumidified air is heated by causing one of two heat exchangers provided in an indoor unit to function as a condenser and the other to function as an evaporator. there is

In Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-34140), by changing the opening degree of an electronic expansion valve provided between two heat exchangers in an indoor unit, air that can perform reheat dehumidification operation A harmonizing device is disclosed.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-34140) does not disclose a suitable method for controlling the degree of opening of the electronic expansion valve in the indoor unit during execution of the reheat dehumidifying operation.

The air conditioner of the first aspect includes a first unit, a second unit, a refrigerant circuit, and a controller. The first unit has a compressor and a first heat exchanger. The second unit has a second heat exchanger, an expansion valve and a third heat exchanger. In the refrigerant circuit, the compressor, the first heat exchanger, the second heat exchanger, the expansion valve and the third heat exchanger are connected in a ring, and the refrigerant circulates. The control unit controls the refrigerant circuit to perform a first operation in which the first heat exchanger and the second heat exchanger function as condensers and the third heat exchanger functions as an evaporator. The expansion valve has a first member and a second member that adjust the degree of opening of the expansion valve. The second member adjusts the degree of opening when the flow rate of the refrigerant passing through the expansion valve is within the first range. The first member adjusts the degree of opening when the flow rate of the refrigerant passing through the expansion valve is greater than the first range. The control unit controls the expansion valve to adjust the degree of opening by the second member so that the state of the refrigerant at the outlet of the third heat exchanger becomes wet during execution of the first operation.

In this air conditioner, when the reheating dehumidification operation is performed in which the air dehumidified by the third heat exchanger is heated by the second heat exchanger, the refrigerant in the third heat exchanger is in a wet state. The degree of opening of the expansion valve is controlled in the control region. As a result, this air conditioner can improve the effect of reheating air in the second heat exchanger when the reheat dehumidification operation is performed.

The air conditioner of the second aspect is the air conditioner of the first aspect, further comprising a discharge pipe and a first temperature sensor. The discharge pipe is connected to the discharge side of the compressor, through which refrigerant compressed by the compressor flows. A first temperature sensor detects the temperature of the discharge pipe. The controller adjusts the degree of opening by the second member based on the temperature detected by the first temperature sensor so that the state of the refrigerant at the outlet of the third heat exchanger becomes wet during execution of the first operation. I do.

In this air conditioner, when the reheat dehumidification operation is executed, the wet state of the refrigerant in the third heat exchanger is estimated based on the temperature of the discharge pipe of the compressor, and the degree of opening of the expansion valve is controlled. As a result, this air conditioner can improve the effect of reheating air in the second heat exchanger when the reheat dehumidification operation is performed.

The air conditioner of the third aspect is the air conditioner of the second aspect, further comprising a second temperature sensor and a third temperature sensor. A second temperature sensor detects the temperature of the first heat exchanger. A third temperature sensor detects the temperature of a pipe connecting the expansion valve and the third heat exchanger. The controller calculates the target temperature of the discharge pipe based on the temperatures detected by the second temperature sensor and the third temperature sensor. Based on the calculated target temperature and the temperature detected by the first temperature sensor, the control unit controls the state of the refrigerant at the outlet of the third heat exchanger to be wet during execution of the first operation. The degree of opening is adjusted by the second member.

In this air conditioner, when the reheat dehumidification operation is executed, the target temperature of the discharge pipe calculated based on the evaporation temperature and condensation temperature of the refrigerant and the actual temperature of the discharge pipe are used to determine the temperature inside the third heat exchanger. The degree of opening of the expansion valve is controlled by estimating the wetness state of the refrigerant. As a result, this air conditioner can improve the effect of reheating air in the second heat exchanger when the reheat dehumidification operation is performed.

The air conditioner of the fourth aspect is the air conditioner of any one of the first to third aspects, and the expansion valve further has a first valve seat forming a first valve port through which the refrigerant passes. The first member forms a second valve port through which refrigerant passes. The controller controls the position of the first member to change the opening of the first valve port, thereby adjusting the opening by the first member. The controller controls the position of the second member to change the degree of opening of the second valve port, thereby adjusting the degree of opening by the second member.

By using a two-stage expansion valve in this air conditioner, the degree of opening of the expansion valve is finely controlled in the small flow rate control range. As a result, the air conditioner can finely adjust the reheating effect when executing the reheat dehumidifying operation.

An air conditioner according to a fifth aspect is the air conditioner according to the fourth aspect, wherein the control unit controls the opening of the first valve port to be equal to or less than a predetermined value when the first operation is executed, and the second member Adjust the opening by

An air conditioner according to a sixth aspect is the air conditioner according to any one of the first to fifth aspects, wherein the control unit controls the refrigerant circuit to cause the first heat exchanger to function as a condenser, In addition, a second operation is further performed in which the second heat exchanger and the third heat exchanger function as evaporators. The control unit controls the expansion valve to adjust the degree of opening by the first member and the second member so that the refrigerant passing through the expansion valve does not decompress during execution of the second operation.

In this air conditioner, by appropriately adjusting the degree of opening of the expansion valve, it is possible to switch between the cooling operation in which the second heat exchanger and the third heat exchanger function as evaporators and the reheat dehumidifying operation. can be done.

An air conditioner according to a seventh aspect is the air conditioner according to the sixth aspect, wherein the control unit adjusts the wetness degree of refrigerant sucked into the compressor during execution of the second operation to The degree of opening is adjusted by the first member and the second member so that the degree of wetness is greater than the degree of wetness of the refrigerant sucked into the compressor.

With this air conditioner, it is possible to switch between cooling operation and reheat dehumidification operation by appropriately adjusting the opening of the expansion valve.

The air conditioner of the eighth aspect is the air conditioner of any one of the first to seventh aspects, further comprising a fourth temperature sensor and a fifth temperature sensor. A fourth temperature sensor detects the temperature of the space in which the second unit is installed. A fifth temperature sensor detects the temperature of the space in which the first unit is installed. At the start of the first operation, the control unit adjusts the second heat exchanger so that the state of the refrigerant at the outlet of the third heat exchanger becomes wet based on the temperatures detected by the fourth temperature sensor and the fifth temperature sensor. The opening is adjusted by the member.

In this air conditioner, when the reheat dehumidifying operation is started, the degree of opening of the expansion valve is controlled by estimating the wet state of the refrigerant in the third heat exchanger based on the room temperature and the outside air temperature. As a result, the air conditioner can realize an appropriate reheat effect when executing the reheat dehumidifying operation.

1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present disclosure; FIG. 3 is a schematic cross-sectional view of an indoor expansion valve 32; FIG. 4 is a graph showing flow characteristics of an indoor expansion valve 32; 3 is a control block diagram of a control unit 6; FIG. 6 is a flowchart of an example of control executed by the control unit 6 during reheat dehumidification operation. 6 is a flowchart of an example of control executed by the control unit 6 during reheat dehumidification operation.

An air conditioner 1 according to an embodiment of the present disclosure will be described with reference to the drawings.

(1) Overall Configuration The air conditioner 1 air-conditions a room such as a building, which is a target space, using a vapor compression refrigerant cycle. As shown in FIG. 1, the air conditioner 1 mainly includes an outdoor unit 2, an indoor unit 3, a liquid refrigerant communication pipe 4, a gas refrigerant communication pipe 5, a controller 6, and a remote controller 7. . The liquid refrigerant communication pipe 4 and the gas refrigerant communication pipe 5 connect the outdoor unit 2 and the indoor unit 3 . The outdoor unit 2 , the indoor unit 3 , the liquid refrigerant communication pipe 4 , and the gas refrigerant communication pipe 5 are annularly connected by refrigerant pipes to form a refrigerant circuit 100 . Refrigerant circuit 100 has a refrigerant sealed therein. The control unit 6 controls the refrigerant circuit 100 to realize a refrigeration cycle, thereby performing air conditioning operations such as heating operation, cooling operation, and reheat dehumidification operation.

(2) Detailed Configuration (2-1) Outdoor Unit The outdoor unit 2 is installed outdoors such as on the roof of the building or near the outer wall surface of the building. The outdoor unit 2 mainly has a compressor 21 , a four-way switching valve 23 , an outdoor heat exchanger 24 , an outdoor expansion valve 25 and an outdoor fan 26 . As shown in FIG. 1, the outdoor unit 2 may further have at least one of a discharge pipe temperature sensor 27, an outdoor heat exchanger temperature sensor 28, and an outdoor temperature sensor 29, if necessary.

(2-1-1) Compressor In the refrigerant circuit 100, the compressor 21 sucks low-pressure refrigerant from the suction side 21a, compresses it to high pressure, and then discharges it from the discharge side 21b. A discharge pipe 21c through which the refrigerant compressed by the compressor 21 flows is connected to the discharge side 21b of the compressor 21 . The compressor 21 is a closed-type compressor in which a displacement type compression element such as a rotary type or a scroll type is rotationally driven by a motor 22 . The rotation speed of the motor 22 is controlled by the controller 6 via an inverter or the like.

(2-1-2) Four-Way Switching Valve The four-way switching valve 23 switches the direction of refrigerant flow in the refrigerant circuit 100 . The four-way switching valve 23 has a first port P1, a second port P2, a third port P3, and a fourth port P4. The four-way selector valve 23 is switched between a first state (shown by broken lines in FIG. 1) and a second state (shown by solid lines in FIG. 1) by the control unit 6 . In the first state, the first port P1 and the fourth port P4 communicate with each other, and the second port P2 and the third port P3 communicate with each other. In the second state, the first port P1 and the second port P2 communicate with each other, and the third port P3 and the fourth port P4 communicate with each other.

The first port P1 is connected to the discharge side 21b of the compressor 21. The second port P<b>2 is connected to the gas side 24 b of the outdoor heat exchanger 24 . The third port P3 is connected to the suction side 21a of the compressor 21 . A fourth port P4 is connected to the gas refrigerant communication pipe 5 . The discharge pipe 21 c connects the discharge side 21 b of the compressor 21 and the first port P<b>1 of the four-way switching valve 23 .

(2-1-3) Outdoor Heat Exchanger The outdoor heat exchanger 24 exchanges heat between the refrigerant in the outdoor heat exchanger 24 and the outdoor air in the refrigerant circuit 100 . A liquid side 24 a of the outdoor heat exchanger 24 is connected to an outdoor expansion valve 25 . A gas side 24 b of the outdoor heat exchanger 24 is connected to the second port P 2 of the four-way switching valve 23 .

(2-1-4) Outdoor Expansion Valve The outdoor expansion valve 25 is an expansion mechanism that reduces the pressure of the refrigerant in the refrigerant circuit 100 . The outdoor expansion valve 25 is provided between the liquid refrigerant communication pipe 4 and the liquid side 24 a of the outdoor heat exchanger 24 . The outdoor expansion valve 25 is an electric expansion valve whose degree of opening can be adjusted. The degree of opening of the outdoor expansion valve 25 is controlled by the controller 6 .

(2-1-5) Outdoor Fan The outdoor fan 26 generates airflow and supplies outdoor air to the outdoor heat exchanger 24 . The outdoor fan 26 causes the outdoor air to pass through the outdoor heat exchanger 24, thereby promoting heat exchange between the refrigerant in the outdoor heat exchanger 24 and the outdoor air. The outdoor fan 26 is rotationally driven by an outdoor fan motor 26a. The air volume of the outdoor fan 26 is controlled by the controller 6 changing the rotation speed of the outdoor fan motor 26a.

(2-1-6) Discharge Pipe Temperature Sensor A discharge pipe temperature sensor 27 is provided on the discharge pipe 21c. A discharge pipe temperature sensor 27 detects the temperature of the refrigerant discharged from the compressor 21 (discharge pipe temperature).

(2-1-7) Outdoor Heat Exchanger Temperature Sensor The outdoor heat exchanger temperature sensor 28 is provided in the outdoor heat exchanger 24 . The outdoor heat exchanger temperature sensor 28 detects the temperature (condensation temperature) of the refrigerant in the refrigerant circuit 100 in the refrigeration cycle when the four-way switching valve 23 is in the second state.

(2-1-8) Outdoor Temperature Sensor The outdoor temperature sensor 29 is provided at the air inlet of the casing (not shown) of the outdoor unit 2 . The outdoor temperature sensor 29 detects the temperature of the outdoor air flowing into the casing of the outdoor unit 2 (outdoor temperature).

(2-2) Indoor Unit The indoor unit 3 is installed in the room, which is the target space. The indoor unit 3 mainly has a first indoor heat exchanger 311 , a second indoor heat exchanger 312 , an indoor expansion valve 32 and an indoor fan 33 . As shown in FIG. 1, the indoor unit 3 may further have at least one of an indoor temperature sensor 34 and an indoor heat exchanger temperature sensor 36, if necessary.

(2-2-1) First indoor heat exchanger and second indoor heat exchanger The first indoor heat exchanger 311 is the refrigerant in the first indoor heat exchanger 311 and the indoor air in the refrigerant circuit 100. heat exchange. One end of the first indoor heat exchanger 311 is connected to the liquid refrigerant communication pipe 4 . The other end of the first indoor heat exchanger 311 is connected to the indoor expansion valve 32 via the first indoor pipe 32a.

The second indoor heat exchanger 312 exchanges heat between the refrigerant in the second indoor heat exchanger 312 and the indoor air in the refrigerant circuit 100 . One end of the second indoor heat exchanger 312 is connected to the indoor expansion valve 32 via the second indoor pipe 32b. The other end of the second indoor heat exchanger 312 is connected to the gas refrigerant communication pipe 5 .

The first indoor heat exchanger 311 and the second indoor heat exchanger 312 are arranged in the air flow path generated by the indoor fan 33 . The first indoor heat exchanger 311 is arranged downstream of the second indoor heat exchanger 312 in the direction of the airflow generated by the indoor fan 33 . In other words, the indoor air is first heat-exchanged with the refrigerant in the second indoor heat exchanger 312 and then heat-exchanged with the refrigerant in the first indoor heat exchanger 311 by the airflow generated by the indoor fan 33. be.

(2-2-2) Indoor Expansion Valve The indoor expansion valve 32 is an expansion mechanism that reduces the pressure of the refrigerant in the refrigerant circuit 100 . The indoor expansion valve 32 is provided between the first indoor heat exchanger 311 and the second indoor heat exchanger 312 in the refrigerant circuit 100 . The indoor expansion valve 32 is an electric expansion valve whose opening degree can be adjusted. The degree of opening of the indoor expansion valve 32 is controlled by the controller 6 .

As shown in FIG. 2, the indoor expansion valve 32 mainly has a valve chamber 321, a main valve body 322, a sub-valve body 323, and a driving portion 324.

The valve chamber 321 is a cylindrical member that accommodates the main valve body 322 inside. The valve chamber 321 is formed with a main communication hole 321a, which is a fluid inlet, on a side surface, and a main valve port 321b, which is a fluid outlet, on one end.

The main valve body 322 is a cylindrical member that is housed inside the valve chamber 321 and changes the opening degree of the main valve port 321b. The main valve body 322 is formed with a sub-valve port 322a, which is a fluid outlet, at one end. A ring-shaped retainer 322b is attached to the other end of the main valve body 322 . The main valve body 322 has a side surface formed with a sub-communication hole 322c serving as a fluid inlet.

The sub-valve element 323 is a needle-like member that changes the degree of opening of the sub-valve port 322a and lifts the main valve element 322. A part of the sub-valve element 323 is inserted inside the main valve element 322 through the opening of the retainer 322b. The sub valve body 323 has a tapered portion 323 a formed at the end on the side to be inserted into the main valve body 322 , and the end opposite to the tapered portion 323 a is fixed to the driving portion 324 . The sub-valve element 323 has a flange-like projection 323b formed on the side surface of the portion closer to the tapered portion 323a than the retainer 322b when inserted into the main valve element 322. As shown in FIG.

The drive unit 324 drives the main valve body 322 and the sub-valve body 323 in the axial direction. The drive unit 324 is driven by an output pulse, which is a control signal output by the control unit 6 . In other words, the degree of opening of the indoor expansion valve 32 is controlled by the controller 6 . The unit operation amount for the indoor expansion valve 32 is 1 pulse, and the opening degree of the indoor expansion valve 32 increases as the drive pulse output by the control unit 6 increases.

The graph shown in FIG. 3 shows the flow rate characteristic, which is the relationship between the opening degree (driving pulse) of the indoor expansion valve 32 and the flow rate of the refrigerant passing through the indoor expansion valve 32 . As shown in FIG. 3, the flow rate characteristics of the indoor expansion valve 32 are divided into a small flow rate control region in which the change in flow rate per unit operation amount (unit driving pulse) is small, and a small flow rate control region in which the change in flow rate per unit operation amount is smaller than the small flow control region. It has two flow control regions consisting of a large high flow control region. The refrigerant flow rate in the large flow rate control region is greater than the refrigerant flow rate in the small flow rate control region. The degree of opening (%) of the indoor expansion valve 32 is the percentage of the drive pulse to the drive pulse output by the controller 6 to fully open the indoor expansion valve 32 . In the air conditioner 1, the drive pulse for fully opening the indoor expansion valve 32 is 500 pulses.

(2-2-3) Indoor Fan The indoor fan 33 generates airflow and supplies indoor air to the first indoor heat exchanger 311 and the second indoor heat exchanger 312 . By the indoor air passing through the second indoor heat exchanger 312 and the first indoor heat exchanger 311 in order by the indoor fan 33, the refrigerant in the first indoor heat exchanger 311 and the second indoor heat exchanger 312, Promotes heat exchange with indoor air. The indoor fan 33 is rotationally driven by an indoor fan motor 33a. The air volume of the indoor fan 33 is controlled by the controller 6 changing the rotation speed of the indoor fan motor 33a.

(2-2-4) Indoor Temperature Sensor The indoor temperature sensor 34 is provided at the air intake port of the casing (not shown) of the indoor unit 3 . The indoor temperature sensor 34 detects the temperature of indoor air flowing into the casing of the indoor unit 3 (indoor temperature).

(2-2-5) Indoor Heat Exchanger Temperature Sensor The indoor heat exchanger temperature sensor 36 is provided in the second indoor pipe 32b that connects the indoor expansion valve 32 and the second indoor heat exchanger 312 together. Indoor heat exchanger temperature sensor 36 detects the temperature (evaporation temperature) of the refrigerant in refrigerant circuit 100 in the refrigeration cycle when four-way switching valve 23 is in the second state.

(2-3) Control Unit As shown in FIG. 4, the control unit 6 includes a compressor 21, a four-way switching valve 23, an outdoor expansion valve 25, an outdoor fan 26, an indoor expansion valve 32, an indoor The fan 33 and the remote controller 7 are connected so as to be able to transmit and receive control signals. The control unit 6, as necessary, from each of the discharge pipe temperature sensor 27, the outdoor heat exchanger temperature sensor 28, the outdoor temperature sensor 29, the indoor temperature sensor 34, and the indoor heat exchanger temperature sensor 36, It is connected so as to be able to receive a detection signal.

The control unit 6 controls the operation of the compressor 21, the four-way switching valve 23, the outdoor expansion valve 25, the outdoor fan 26, the indoor expansion valve 32, and the indoor fan 33, thereby controlling the refrigerant circuit 100. do.

The control unit 6 is typically a computer that mainly includes a control arithmetic device and a storage device. The control computing device is a processor such as a CPU or GPU. The control arithmetic unit reads out the control program stored in the storage device and performs operation control according to this control program. The control arithmetic unit can write the arithmetic result to the storage device and read the information stored in the storage device according to the control program.

The control unit 6 is composed of an outdoor control unit provided inside the outdoor unit 2 and an indoor control unit provided inside the indoor unit 3, which are connected to each other by a communication line capable of transmitting and receiving control signals. good too.

(2-4) Remote Controller The remote controller 7 accepts instructions from the user to execute any one of heating operation, cooling operation, and reheat dehumidification operation, indoor target temperature, indoor target humidity, etc., and controls the received data. It is transmitted to the control unit 6 as a signal. Upon receiving the control signal, the control unit 6 records it in the storage device.

The remote control 7 has a display section 71 . The display unit 71 displays information such as the air conditioning operation mode being executed, the indoor target temperature, the indoor target humidity, the indoor temperature, and the indoor humidity.

(3) Operation (3-1) Operation of indoor expansion valve When the driving pulse output from the control unit 6 is 0 pulse, the main valve body 322 is seated in the valve chamber 321 to close the main valve port 321b, and The sub-valve element 323 is seated on the main valve element 322 to close the sub-valve port 322a. At this time, the degree of opening of the indoor expansion valve 32 is 0% (=(0 pulse/500 pulses)×100). Also, at this time, a slight gap (not shown) is formed between the valve chamber 321 and the main valve element 322 at the main valve port 321b. Therefore, even if the degree of opening of the indoor expansion valve 32 is 0%, the flow rate of the refrigerant passing through the indoor expansion valve 32 is not zero, and a very small amount of refrigerant flows inside the indoor expansion valve 32 .

When the control unit 6 increases the drive pulse from 0 pulse, the drive unit 324 moves the sub-valve body 323 away from the sub-valve port 322a along the axial direction. Until the drive pulse reaches 150 pulses, the main valve body 322 continues to be seated in the valve chamber 321, and only the sub-valve body 323 moves to change the opening degree of the sub-valve port 322a. When the sub-valve port 322a opens, the refrigerant flows through the main communication hole 321a of the valve chamber 321, the sub-communication hole 322c of the main valve element 322, the sub-valve port 322a of the main valve element 322, and the main valve port 321b of the valve chamber 321. It flows out through the channel formed by When the drive pulse reaches 150 pulses, the opening degree of the indoor expansion valve 32 is 30% (=(150 pulses/500 pulses)×100). When the drive pulse reaches 150 pulses, the sub-valve port 322a is fully opened. In the indoor expansion valve 32, the range in which the drive pulse changes from 0 pulses to 150 pulses and the opening degree of the sub-valve port 322a is changed by the sub-valve body 323 becomes the small flow rate control region. In other words, the range (first range) in which the degree of opening of the indoor expansion valve 32 is 0% or more and 30% or less is the small flow control range.

When the control unit 6 further increases the drive pulse from 150 pulses, the projection 323b of the sub-valve element 323 contacts the retainer 322b of the main valve element 322, and the sub-valve element 323 lifts the main valve element 322. In other words, the drive unit 324 moves the sub valve body 323 away from the main valve port 321b along the axial direction, thereby moving the main valve body 322 away from the main valve port 321b. As a result, when the number of drive pulses exceeds 150 pulses, the main valve element 322 moves to change the degree of opening of the main valve port 321b while the sub-valve port 322a is fully open. When the main valve port 321b is opened, the refrigerant flows directly from the main communication hole 321a, in addition to the flow paths formed by the main communication hole 321a, the sub-communication hole 322c, the sub-valve port 322a, and the main valve port 321b. It exits through a flow path that flows toward the main valve port 321b.

The control unit 6 can increase the drive pulse up to 500 pulses. When the number of drive pulses reaches 500 pulses, the degree of opening of the indoor expansion valve 32 is 100% (=(500 pulses/500 pulses)×100). At this time, both the main valve port 321b and the sub-valve port 322a are fully opened. In the indoor expansion valve 32, the range in which the drive pulse changes from 150 pulses to 500 pulses and the opening degree of the main valve port 321b is changed by the main valve element 322 becomes the large flow rate control region. In other words, the range in which the degree of opening of the indoor expansion valve 32 is greater than 30% and less than or equal to 100% is the large flow rate control region.

(3-2) Air Conditioning Operation The heating operation, cooling operation, and reheat dehumidification operation, which are the air conditioning operations of the air conditioner 1 executed by the control unit 6, will be described. As shown in FIG. 1, in the refrigerant circuit 100 of the air conditioner 1, the compressor 21, the outdoor heat exchanger 24, the outdoor expansion valve 25, the first indoor heat exchanger 311, the indoor expansion valve 32, the second indoor heat Exchangers 312 are connected in a ring.

(3-2-1) Heating operation When the control unit 6 receives a control signal for starting the heating operation from the remote control 7, the air conditioner 1 starts the heating operation. During the heating operation, the controller 6 switches the four-way switching valve 23 to the first state (the state indicated by the dashed line in FIG. 1). Further, the control unit 6 sets the outdoor expansion valve 25 to the degree of opening corresponding to the target temperature received from the remote control 7, and sets the indoor expansion valve 32 to a fully open or nearly fully open degree to operate the compressor 21. As a result, the outdoor heat exchanger 24 functions as a refrigerant evaporator (heat absorber), and the first indoor heat exchanger 311 and the second indoor heat exchanger 312 function as refrigerant condensers (radiators). .

During heating operation, the refrigerant circuit 100 functions as follows. The high-pressure refrigerant discharged from the compressor 21 exchanges heat with the indoor air supplied by the indoor fan 33 in the second indoor heat exchanger 312 and the first indoor heat exchanger 311 and is condensed. As a result, the air in the room is heated and discharged into the room as conditioned air. After the condensed refrigerant passes through the outdoor expansion valve 25 and is decompressed, it exchanges heat with the outdoor air supplied by the outdoor fan 26 in the outdoor heat exchanger 24 and evaporates. The refrigerant that has passed through the outdoor heat exchanger 24 is sucked into the compressor 21 and compressed.

(3-2-2) Cooling operation When the control unit 6 receives a control signal for starting the cooling operation (second operation) from the remote controller 7, the air conditioner 1 starts the cooling operation. During the cooling operation, the controller 6 switches the four-way switching valve 23 to the second state (the state indicated by the solid line in FIG. 1). Further, the control unit 6 sets the outdoor expansion valve 25 to the degree of opening corresponding to the target temperature received from the remote control 7, and sets the indoor expansion valve 32 to a fully open or nearly fully open degree to operate the compressor 21. As a result, the outdoor heat exchanger 24 functions as a refrigerant condenser (radiator), and the first indoor heat exchanger 311 and the second indoor heat exchanger 312 function as refrigerant evaporators (heat absorbers). .

During cooling operation, the refrigerant circuit 100 functions as follows. The high-pressure refrigerant discharged from the compressor 21 exchanges heat with the outdoor air supplied by the outdoor fan 26 in the outdoor heat exchanger 24 and is condensed. After the condensed refrigerant passes through the outdoor expansion valve 25 and is decompressed, it exchanges heat with the indoor air supplied by the indoor fan 33 in the first indoor heat exchanger 311 and the second indoor heat exchanger 312. Evaporate. As a result, the indoor air is cooled and discharged indoors as conditioned air. The refrigerant that has passed through the first indoor heat exchanger 311 and the second indoor heat exchanger 312 is sucked into the compressor 21 and compressed.

(3-2-3) Reheat dehumidification operation When the control unit 6 receives a control signal for starting the reheat dehumidification operation (first operation) from the remote controller 7, the reheat dehumidification operation of the air conditioner 1 is started. . The reheat dehumidification operation is an air conditioning operation in which the second indoor heat exchanger 312 dehumidifies indoor air and the first indoor heat exchanger 311 heats the dehumidified air. During the reheat dehumidification operation, the control unit 6 switches the four-way switching valve 23 to the second state (the state indicated by the solid line in FIG. 1). Further, the control unit 6 sets the outdoor expansion valve 25 to a full opening or an opening close to full opening, and sets the indoor expansion valve 32 to an opening corresponding to the dehumidification load based on the target humidity received from the remote controller 7. to drive. As a result, the outdoor heat exchanger 24 and the first indoor heat exchanger 311 function as a refrigerant condenser (radiator), and the second indoor heat exchanger 312 functions as a refrigerant evaporator (heat absorber). .

During the reheat dehumidification operation, the refrigerant circuit 100 functions as follows. The high-pressure refrigerant discharged from the compressor 21 exchanges heat with the outdoor air supplied by the outdoor fan 26 in the outdoor heat exchanger 24 and is condensed. After passing through the outdoor expansion valve 25 , the refrigerant condensed in the outdoor heat exchanger 24 is also condensed in the first indoor heat exchanger 311 by exchanging heat with indoor air supplied by the indoor fan 33 . The refrigerant condensed in the first indoor heat exchanger 311 passes through the indoor expansion valve 32 and is decompressed, and then exchanges heat with the indoor air supplied by the indoor fan 33 in the second indoor heat exchanger 312. Evaporate. As a result, the indoor air is dehumidified by the second indoor heat exchanger 312 and then heated by the first indoor heat exchanger 311, and the dehumidified air whose temperature drop is suppressed is discharged indoors as conditioned air. be done. The refrigerant that has passed through the second indoor heat exchanger 312 is sucked into the compressor 21 and compressed.

(3-3) Control during reheat dehumidification operation When the reheat dehumidification operation is executed, the control unit 6 controls the sub valve body 323 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes wet. controls the indoor expansion valve 32 in the small flow rate control region where the opening degree of the auxiliary valve port 322a is changed by . In other words, the controller 6 adjusts the opening degree of the indoor expansion valve 32 by moving the sub-valve element 323 to change the opening degree of the sub-valve port 322a when the reheat dehumidification operation is executed. When the state of the refrigerant at the outlet of the second indoor heat exchanger 312 is wet, the refrigerant discharged from the second indoor heat exchanger 312 is not superheated steam, and the refrigerant in the second indoor heat exchanger 312 is wet. It becomes steam.

The control unit 6 maintains the degree of opening of the main valve port 321b at a predetermined value or less during execution of the reheat dehumidification operation. The predetermined value is 0% or substantially 0%, in which case the main valve port 321b is closed by the main valve body 322. However, as described above, even when the main valve port 321b is closed, a slight gap is formed between the valve chamber 321 and the main valve body 322, so that a minute amount of water passing through the main valve port 321b A volume of refrigerant flow occurs.

The control unit 6 performs the reheat dehumidification operation by switching between the first mode and the second mode, which are operation modes with different dehumidification capabilities. The dehumidification capacity of the first mode is lower than the dehumidification capacity of the second mode. The opening degree of the indoor expansion valve 32 in the first mode (hereinafter referred to as the first opening degree) is smaller than the opening degree of the indoor expansion valve 32 in the second mode (hereinafter referred to as the second opening degree). Specifically, at the first degree of opening, most of the refrigerant that has passed through the indoor expansion valve 32 and flowed into the second indoor heat exchanger 312 evaporates near the indoor expansion valve 32 in the second indoor heat exchanger 312. It is set to the degree of opening that provides the desired flow rate. On the other hand, the second degree of opening is the degree of opening at which the flow rate of the refrigerant that has passed through the indoor expansion valve 32 and flowed into the second indoor heat exchanger 312 evaporates in the second indoor heat exchanger 312 as a whole. set. As a result, the reheat dehumidifying operation when the indoor expansion valve 32 is at the second opening degree passes through the indoor expansion valve 32 to the second indoor heat exchanger 312 more than when the indoor expansion valve 32 is at the first opening degree. Since the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 is large, the area where the second indoor heat exchanger 312 functions as an evaporator is widened, exhibiting a high dehumidification capability. In the air conditioner 1, for example, as shown in FIG. 2 The degree of opening is set to 30% (=(150 pulses/500 pulses)×100). The values of the first degree of opening and the second degree of opening are not limited to the values shown in FIG.

The control unit 6 starts the reheat dehumidification operation in the first mode or the second mode, and switches between the first mode and the second mode based on instructions from the user when the reheat dehumidification operation is executed. Specifically, when the control unit 6 receives a control signal for switching between the first mode and the second mode from the remote controller 7 during execution of the reheat dehumidification operation, the control unit 6 transmits the received control signal to the control unit 6. Send. Upon receiving the control signal for switching between the first mode and the second mode, the controller 6 switches between the first mode and the second mode based on the received control signal. When the controller 6 receives from the remote control 7 an instruction to perform an air conditioning operation (for example, a cooling operation) other than the reheat dehumidifying operation or an instruction to stop the operation of the air conditioner 1, it ends the reheat dehumidifying operation.

Next, several specific examples of controlling the indoor expansion valve 32 so that the refrigerant at the outlet of the second indoor heat exchanger 312 becomes wet when the reheat dehumidification operation is executed will be described.

(3-3-1) Control based on degree of opening of indoor expansion valve In this control, the controller 6 maintains the degree of opening of the indoor expansion valve 32 at a predetermined value or more in the small flow rate control region. As a result, a sufficient flow rate of the refrigerant flowing into the second indoor heat exchanger 312 is ensured. Thereby, the control unit 6 estimates that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 has become wet. For example, the controller 6 may maintain the degree of opening of the indoor expansion valve 32 at 30%, which is the second degree of opening.

(3-3-2) Control Based on Discharge Pipe Temperature This control is performed according to the flowchart shown in FIG. First, the controller 6 acquires the discharge pipe temperature detected by the discharge pipe temperature sensor 27 (step S11). Next, the controller 6 determines whether or not the discharge pipe temperature is higher than a predetermined target discharge pipe temperature (step S12). When the discharge pipe temperature is higher than the target discharge pipe temperature, the control unit 6 estimates that the second indoor heat exchanger 312 is in a dry state (a state in which superheated steam is present in the second indoor heat exchanger 312) ( step S13). In this case, the controller 6 increases the degree of opening of the indoor expansion valve 32 in the small flow rate control region to increase the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 (step S14). This reduces the discharge pipe temperature. After a predetermined period of time has elapsed, the controller 6 acquires the discharge pipe temperature again (step S11), and determines whether or not the discharge pipe temperature is higher than the target discharge pipe temperature (step S12). When the discharge pipe temperature becomes equal to or lower than the target discharge pipe temperature, the controller 6 estimates that the refrigerant at the outlet of the second indoor heat exchanger 312 is in a wet state (step S15). After that, the control unit 6 determines whether or not the reheat dehumidification operation has been completed in response to an instruction to execute the cooling operation or the like (step S16). If the reheat dehumidification operation has not ended, the process of controlling the degree of opening of the indoor expansion valve 32 is executed again. Therefore, during the execution of the reheat dehumidification operation, the process of controlling the degree of opening of the indoor expansion valve 32 based on the discharge pipe temperature is continuously executed.

The method by which the control unit 6 estimates whether or not the second indoor heat exchanger 312 is in a dry state based on the target discharge pipe temperature and the discharge pipe temperature is not particularly limited. For example, the control unit 6 may estimate that the second indoor heat exchanger 312 is in a dry state when the discharge pipe temperature is maintained higher than the target discharge pipe temperature for a predetermined time.

(3-3-3) Control Based on Condensing Temperature and Evaporating Temperature This control is performed according to the flowchart shown in FIG. First, the control unit 6 detects the discharge pipe temperature detected by the discharge pipe temperature sensor 27, the refrigerant condensation temperature detected by the outdoor heat exchanger temperature sensor 28, and the refrigerant evaporation detected by the indoor heat exchanger temperature sensor 36. temperature is obtained (step S21). Next, based on the condensation temperature and the evaporation temperature, the control unit 6 calculates a target discharge pipe temperature such that the refrigerant at the outlet of the second indoor heat exchanger 312 becomes wet (step S22). Next, the controller 6 determines whether or not the discharge pipe temperature is higher than the target discharge pipe temperature (step S23). When the discharge pipe temperature is higher than the target discharge pipe temperature, the controller 6 estimates that the second indoor heat exchanger 312 is in a dry state (step S24). In this case, the controller 6 increases the degree of opening of the indoor expansion valve 32 in the small flow rate control region to increase the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 (step S25). This reduces the discharge pipe temperature. After a predetermined time has elapsed, the control unit 6 acquires the discharge pipe temperature, the condensation temperature, and the evaporation temperature again (step S21), calculates the target discharge pipe temperature (step S22), and the discharge pipe temperature reaches the target discharge temperature. It is determined whether or not it is higher than the tube temperature (step S23). When the discharge pipe temperature becomes equal to or lower than the target discharge pipe temperature, the controller 6 estimates that the refrigerant at the outlet of the second indoor heat exchanger 312 is in a wet state (step S26). After that, the control unit 6 determines whether or not the reheat dehumidifying operation has been completed in response to an instruction to execute the cooling operation or the like (step S27). If the reheat dehumidification operation has not ended, the process of controlling the degree of opening of the indoor expansion valve 32 is executed again. Therefore, during execution of the reheat dehumidification operation, the process of controlling the degree of opening of the indoor expansion valve 32 based on the condensation temperature and the evaporation temperature is continuously executed.

The control unit 6 calculates the target discharge pipe temperature based on the condensation temperature and the evaporation temperature, and whether the second indoor heat exchanger 312 is dry based on the target discharge pipe temperature and the discharge pipe temperature. A method for estimating whether or not is not particularly limited. For example, the control unit 6 may calculate the target discharge pipe temperature by substituting the condensing temperature and the evaporating temperature into a predetermined formula, or the relationship between the condensing temperature, the evaporating temperature, and the target discharge pipe temperature may be recorded. The table may be stored and the target discharge pipe temperature may be acquired using the table. Further, the control unit 6 may estimate that the second indoor heat exchanger 312 is in a dry state when the discharge pipe temperature is maintained higher than the target discharge pipe temperature for a predetermined time.

(4) Features (4-1)
In the air conditioner 1, the control unit 6 controls the indoor expansion valve 32 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes wet when the reheat dehumidification operation is executed, and the sub valve The opening is adjusted by the body 323 . When the reheat dehumidification operation is executed, if the degree of subcooling of the refrigerant at the outlet of the first indoor heat exchanger 311 becomes excessive and the condensation temperature becomes low, the air dehumidified by the second indoor heat exchanger 312 is transferred to the first indoor heat. The reheating effect heated by the exchanger 311 may be reduced. During the reheat dehumidification operation, the air conditioner 1 adjusts the opening degree of the indoor expansion valve 32 according to the state of the refrigerant in the second indoor heat exchanger 312. Controlling the degree of subcooling of the refrigerant prevents the condensing temperature from dropping excessively. Thereby, the air conditioner 1 can improve the reheating effect of the air in the first indoor heat exchanger 311 .

(4-2)
In the air conditioner 1, the control unit 6 moves the sub-valve element 323 in the small flow rate control region where the change in the flow rate with respect to the unit operation amount of the indoor expansion valve 32 is small during execution of the reheat dehumidification operation, thereby expanding the room. The degree of opening of the valve 32 is adjusted. As a result, the control unit 6 can finely control the degree of subcooling of the refrigerant at the outlet of the first indoor heat exchanger 311 by finely adjusting the flow rate of the refrigerant flowing into the second indoor heat exchanger 312. . As a result, the controller 6 can finely control the air reheating effect in the first indoor heat exchanger 311 . As a result, in the reheat dehumidifying operation, the air conditioner 1 can reheat the air in the first indoor heat exchanger 311 more effectively than when the opening degree is controlled over the entire flow rate characteristic of the indoor expansion valve 32. can be improved appropriately.

(4-3)
In the air conditioner 1 , the controller 6 may control the degree of opening of the indoor expansion valve 32 based on the discharge pipe temperature detected by the discharge pipe temperature sensor 27 . In this case, the control unit 6 estimates the state of the refrigerant in the second indoor heat exchanger 312 based on a comparison between a predetermined target discharge pipe temperature and the discharge pipe temperature, The degree of opening of the indoor expansion valve 32 is controlled so that the state of the refrigerant at is wet. As a result, the air conditioner 1 can appropriately improve the reheating effect of the air in the first indoor heat exchanger 311 based on the detection value of the temperature sensor provided in the refrigerant circuit 100 during the reheat dehumidification operation. can.

(4-4)
In the air conditioner 1, the control unit 6 controls the discharge pipe temperature detected by the discharge pipe temperature sensor 27, the condensation temperature of the refrigerant detected by the outdoor heat exchanger temperature sensor 28, and the indoor heat exchanger temperature sensor 36. The degree of opening of the indoor expansion valve 32 may be controlled based on the evaporation temperature of the refrigerant. In this case, the control unit 6 estimates the state of the refrigerant in the second indoor heat exchanger 312 based on a comparison between the target discharge pipe temperature calculated from the condensation temperature and the evaporation temperature, and the discharge pipe temperature. The degree of opening of the indoor expansion valve 32 is controlled so that the state of the refrigerant at the outlet of the heat exchanger 312 becomes wet. As a result, the air conditioner 1 can appropriately improve the reheating effect of the air in the first indoor heat exchanger 311 based on the detection value of the temperature sensor provided in the refrigerant circuit 100 during the reheat dehumidification operation. can.

(4-5)
In the air conditioner 1, the controller 6 can easily switch between the reheat dehumidification operation and the cooling operation by appropriately adjusting the opening degrees of the outdoor expansion valve 25 and the indoor expansion valve 32. Specifically, the control unit 6 sets the outdoor expansion valve 25 to a full opening or an opening close to full opening, and sets the indoor expansion valve 32 to an opening in the small flow rate control region, thereby executing the reheat dehumidification operation. . In addition, the control unit 6 can perform the cooling operation by setting the outdoor expansion valve 25 to a predetermined opening degree and setting the indoor expansion valve 32 to a fully opened or nearly fully opened opening degree.

(5) Modification (5-1) Modification A
During the reheat dehumidification operation, as long as the refrigerant is moist at the outlet of the second indoor heat exchanger 312, the degree of superheat of the refrigerant sucked into the compressor 21 may be somewhat high. However, during the cooling operation, it is preferable that the degree of superheat of the refrigerant sucked into the compressor 21 is low. Therefore, the control unit 6 controls the wetness degree of the refrigerant sucked into the compressor 21 when the cooling operation is executed to be higher than the wetness degree of the refrigerant sucked into the compressor 21 when the reheat dehumidification operation is executed. The degree of opening of the indoor expansion valve 32 may be adjusted. The degree of wetness of the refrigerant is the weight ratio of the liquid refrigerant in the wet vapor of the refrigerant. The control unit 6 adjusts the opening degree of the indoor expansion valve 32 by moving the main valve element 322 and the sub-valve element 323 in the entire flow rate control region (the small flow rate control region and the large flow rate control region) during execution of the cooling operation. I do. By appropriately adjusting the opening degrees of the outdoor expansion valve 25 and the indoor expansion valve 32, the air conditioner 1 can appropriately switch between the cooling operation and the reheat dehumidification operation.

(5-2) Modification B
At the start of the reheat dehumidifying operation, the control unit 6 controls the amount of refrigerant at the outlet of the second indoor heat exchanger 312 based on the indoor temperature detected by the indoor temperature sensor 34 and the outdoor temperature detected by the outdoor temperature sensor 29. The opening degree of the indoor expansion valve 32 may be adjusted in the small flow rate control region so that the state becomes wet. In this case, when the reheat dehumidifying operation is started, the air conditioner 1 estimates the state of the refrigerant in the second indoor heat exchanger 312 based on the indoor temperature and the outdoor temperature, The degree of opening of the indoor expansion valve 32 is controlled so that the state of the refrigerant at the outlet becomes wet. As a result, the air conditioner 1 can appropriately improve the reheating effect of the air in the first indoor heat exchanger 311 based on the detection value of the temperature sensor provided in the refrigerant circuit 100 during the reheat dehumidification operation. can.

(5-3) Modification C
When executing the reheat dehumidification operation, the control unit 6 estimates the state of the refrigerant in the second indoor heat exchanger 312 based on the evaporator outlet temperature or the compressor suction temperature instead of the target discharge pipe temperature, The degree of opening of the indoor expansion valve 32 may be controlled so that the refrigerant at the outlet of the second indoor heat exchanger 312 is wet. The evaporator outlet temperature is, for example, the temperature detected by a temperature sensor provided in the refrigerant pipe near the outlet of the second indoor heat exchanger 312 . The compressor suction temperature is, for example, the temperature detected by a temperature sensor provided in the refrigerant pipe near the suction side of the compressor 21 .

In this case, for example, when the evaporator outlet temperature or the compressor suction temperature is within a predetermined range, the control unit 6 estimates that the second indoor heat exchanger 312 is in a dry state, and The degree of opening of the expansion valve 32 is increased to increase the flow rate of refrigerant flowing into the second indoor heat exchanger 312 . In addition, when the evaporator outlet temperature or the compressor suction temperature deviates from the predetermined range, the control unit 6 estimates that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 has become wet, and the indoor expansion valve Stop changing the opening of 32.

Further, the control unit 6 calculates the target discharge pipe temperature based on the evaporator outlet temperature and the compressor suction temperature, and controls the degree of opening of the indoor expansion valve 32 based on the target discharge pipe temperature as in the embodiment. may

(5-4) Modification D
The control unit 6 may adjust the degree of opening of the outdoor expansion valve 25 based on the discharge pipe temperature during execution of the cooling operation or the heating operation.

(5-5) Modification E
The remote controller 7 controls the type of operation being executed by the control unit 6 (cooling operation, heating operation, and reheat dehumidification operation), and the operation mode of the reheat dehumidification operation (first mode and second mode), It may be displayed on the display unit 71 .

(5-6) Modification F
For example, the control unit 6 may automatically switch between the reheat dehumidifying operation and the cooling operation based on the indoor humidity. In this case, the controller 6 acquires the indoor humidity from a humidity sensor that detects the humidity of the air flowing into the casing of the indoor unit 3 .

(5-7) Modification G
In the air conditioner 1 according to the embodiment, the control unit 6 performs the reheat dehumidification operation by switching between the first mode and the second mode, which are operation modes with different dehumidification capabilities. However, the number of operation modes that the controller 6 can switch to during the reheat dehumidification operation may be three or more. In this case, the degree of opening of the indoor expansion valve 32 in each operation mode is set differently.

(5-8) Modification H
In the air conditioner 1 according to the embodiment, the controller 6 starts the reheat dehumidifying operation in the first mode or the second mode. In this case, the air conditioner 1 may determine which of the first mode and the second mode should be executed when the reheat dehumidifying operation is started.

For example, when the previous reheat dehumidification operation is terminated, the control unit 6 records information about which of the first mode and the second mode was being executed in the storage device, and then the reheat dehumidification operation is completed. When starting the operation, the information may be referenced to determine which of the first mode and the second mode is to be executed when the reheat dehumidifying operation is started.

In addition, the control unit 6 records information about which of the first mode and the second mode is generally executed for each time period in the storage device, and stores the information when starting the reheat dehumidification operation. By referring to it, it may be determined which of the first mode and the second mode is to be executed at the start of the reheat dehumidifying operation.

- Conclusion -
Although embodiments of the present disclosure have been described above, it will be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims. .

1: Air conditioner 2: Outdoor unit (first unit)
3: Indoor unit (second unit)
6: control unit 21: compressor 21c: discharge pipe 24: outdoor heat exchanger (first heat exchanger)
27: discharge pipe temperature sensor (first temperature sensor)
28: outdoor heat exchanger temperature sensor (second temperature sensor)
29: outdoor temperature sensor (fifth temperature sensor)
311: First indoor heat exchanger (second heat exchanger)
312: Second indoor heat exchanger (third heat exchanger)
32: Indoor expansion valve (expansion valve)
321: Valve chamber (first valve seat)
321b: Main valve port (first valve port)
322: Main valve body (first member)
322a: Sub-valve port (second valve port)
323: Sub-valve body (second member)
34: indoor temperature sensor (fourth temperature sensor)
36: Indoor heat exchanger temperature sensor (third temperature sensor)
100: Refrigerant circuit

Japanese Patent Application Laid-Open No. 2020-34140

Claims

a first unit (2) comprising a compressor (21) and a first heat exchanger (24);
a second unit (3) comprising a second heat exchanger (311), an expansion valve (32) and a third heat exchanger (312);
a refrigerant circuit (100) in which the compressor, the first heat exchanger, the second heat exchanger, the expansion valve, and the third heat exchanger are connected in a ring, and a refrigerant circulates;
A control unit that controls the refrigerant circuit to perform a first operation in which the first heat exchanger and the second heat exchanger function as condensers and the third heat exchanger functions as an evaporator. (6) and
with
The expansion valve has a first member (322) and a second member (323) for adjusting the degree of opening of the expansion valve,
The second member adjusts the degree of opening when the flow rate of the refrigerant passing through the expansion valve is within the first range,
The first member adjusts the degree of opening when the flow rate of the refrigerant passing through the expansion valve is greater than the first range,
When the first operation is executed, the control unit controls the expansion valve so that the state of the refrigerant at the outlet of the third heat exchanger becomes wet, and the degree of opening by the second member is controlled. make adjustments,
An air conditioner (1).
a discharge pipe (21c) connected to the discharge side of the compressor and through which the refrigerant compressed by the compressor flows;
a first temperature sensor (27) for detecting the temperature of the discharge pipe;
further comprising
The control unit controls the temperature detected by the first temperature sensor so that the refrigerant at the outlet of the third heat exchanger becomes wet during execution of the first operation. performing the opening degree adjustment by two members;
The air conditioner according to claim 1.
a second temperature sensor (28) for detecting the temperature of the first heat exchanger;
a third temperature sensor (36) for detecting the temperature of a pipe connecting the expansion valve and the third heat exchanger;
further comprising
The control unit
calculating a target temperature of the discharge pipe based on the temperatures detected by the second temperature sensor and the third temperature sensor;
Based on the target temperature and the temperature detected by the first temperature sensor, when the first operation is executed, the refrigerant is in a wet state at the outlet of the third heat exchanger performing the opening degree adjustment by the second member;
The air conditioner according to claim 2.
the expansion valve further comprises a first valve seat (321) forming a first valve port (321b) through which the refrigerant passes;
the first member forms a second valve port (322a) through which the refrigerant passes;
The control unit
adjusting the opening degree by the first member by changing the opening degree of the first valve port by controlling the position of the first member;
Adjusting the opening degree by the second member by changing the opening degree of the second valve port by controlling the position of the second member;
The air conditioner according to any one of claims 1 to 3.
The control unit performs the opening degree adjustment by the second member when the opening degree of the first valve port is equal to or less than a predetermined value during execution of the first operation.
The air conditioner according to claim 4.
The control unit
further performing a second operation in which the refrigerant circuit is controlled to cause the first heat exchanger to function as a condenser and the second heat exchanger and the third heat exchanger to function as evaporators;
During execution of the second operation, the expansion valve is controlled such that the refrigerant passing through the expansion valve is not decompressed, and the opening is adjusted by the first member and the second member;
The air conditioner according to any one of claims 1 to 5.
The control unit controls that the wetness degree of the refrigerant sucked into the compressor during execution of the second operation is greater than the wetness degree of the refrigerant sucked into the compressor during execution of the first operation. Adjust the opening degree by the first member and the second member so that
The air conditioner according to claim 6.
a fourth temperature sensor (34) for detecting the temperature of the space in which the second unit is installed;
a fifth temperature sensor (29) for detecting the temperature of the space in which the first unit is installed;
further comprising
At the start of the first operation, the control unit changes the state of the refrigerant at the outlet of the third heat exchanger to a wet state based on the temperatures detected by the fourth temperature sensor and the fifth temperature sensor. Adjust the opening degree by the second member so that
The air conditioner according to any one of claims 1 to 7.