Air conditioning unit

Abstract

An air conditioning device is provided which can appropriately control the opening of an electronic expansion valve in an indoor unit during a reheat dehumidification operation. The air conditioning device (1) includes a refrigerant circuit (100) and a control unit (6). In the refrigerant circuit (100), 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) are connected in a ring shape. The control unit (6) controls the refrigerant circuit (100) to perform a first operation, in which the outdoor heat exchanger (24) and the first indoor heat exchanger (311) function as a condenser and the second indoor heat exchanger (312) functions as an evaporator. The indoor expansion valve (32) includes a main valve core (322) and a sub-valve core (323) for adjusting the opening of the indoor expansion valve (32). The flow control range of the main valve core (322) is larger than the flow control range of the sub-valve core (323). When executing the first operation, the control unit (6) controls the indoor expansion valve (32) so that the refrigerant at the outlet of the second indoor heat exchanger (312) becomes humid, thereby adjusting the opening degree of the sub-valve element (323).

Description

Technical Field

[0001] The present disclosure relates to an air conditioning device. Background Art

[0002] There is known an air conditioner that performs a reheat dehumidification operation for heating dehumidified air 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.

[0003] Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-34140) discloses an air conditioning device capable of performing a reheat dehumidification operation by changing the opening degree of an electronic expansion valve provided between two heat exchangers in an indoor unit. Summary of the invention

[0004] Problems to be solved by the invention

[0005] Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-34140) does not disclose an appropriate method for controlling the opening degree of the electronic expansion valve in the indoor unit when performing the reheat dehumidification operation.

[0006] Means for solving problems

[0007] The air conditioning device of the first aspect comprises a first unit, a second unit, a refrigerant circuit and a control unit. The first unit comprises a compressor and a first heat exchanger. The second unit comprises 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 shape for refrigerant circulation. 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 comprises a first component and a second component for adjusting the opening of the expansion valve. The second component adjusts the opening when the flow rate of the refrigerant passing through the expansion valve is within a first range. The first component adjusts the opening when the flow rate of the refrigerant passing through the expansion valve is greater than the first range. When performing the first operation, the control unit controls the expansion valve in such a way that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state, and performs the opening adjustment based on the second component.

[0008] In the air conditioner, when performing a reheat dehumidification operation in which the air dehumidified by the third heat exchanger is heated by the second heat exchanger, the opening of the expansion valve is controlled in the small flow control region so that the refrigerant in the third heat exchanger becomes humid. Thus, when performing the reheat dehumidification operation, the air conditioner can improve the reheating effect of the air in the second heat exchanger.

[0009] The air conditioner of the second aspect is based on the air conditioner of the first aspect, and further includes a discharge pipe and a first temperature sensor. The discharge pipe is connected to the discharge side of the compressor, and the refrigerant compressed by the compressor flows. The first temperature sensor detects the temperature of the discharge pipe. The control unit adjusts the opening of the second component so that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state when performing the first operation based on the temperature detected by the first temperature sensor.

[0010] In the air conditioner, when performing the reheat dehumidification operation, the humidity state of the refrigerant in the third heat exchanger is estimated based on the temperature of the discharge pipe of the compressor, thereby controlling the opening of the expansion valve. As a result, the air conditioner can improve the reheating effect of the air in the second heat exchanger when performing the reheat dehumidification operation.

[0011] The air conditioner of the third viewpoint is based on the air conditioner of the second viewpoint, and further includes a second temperature sensor and a third temperature sensor. The second temperature sensor detects the temperature of the first heat exchanger. The third temperature sensor detects the temperature of the pipe connecting the expansion valve and the third heat exchanger. The control unit calculates the target temperature of the discharge pipe based on the temperatures detected by the second temperature sensor and the third temperature sensor. The control unit adjusts the opening of the second component in a manner that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state based on the calculated target temperature and the temperature detected by the first temperature sensor when performing the first operation.

[0012] In the air conditioner, when performing the reheat dehumidification operation, the humidity state of the refrigerant in the third heat exchanger is estimated based on 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, thereby controlling the opening of the expansion valve. As a result, when performing the reheat dehumidification operation, the air conditioner can improve the reheating effect of the air in the second heat exchanger.

[0013] The air conditioning device of the fourth aspect is the air conditioning device described in any one of the first to third aspects, wherein the expansion valve further has a first valve seat, the first valve seat forming a first valve port through which the refrigerant passes. The first component forms a second valve port through which the refrigerant passes. The control unit changes the opening of the first valve port by controlling the position of the first component, thereby adjusting the opening based on the first component. The control unit changes the opening of the second valve port by controlling the position of the second component, thereby adjusting the opening based on the second component.

[0014] In this air conditioner, by using a two-stage expansion valve, the opening of the expansion valve is finely controlled in a small flow control region, so that the air conditioner can finely adjust the reheating effect when performing a reheat dehumidification operation.

[0015] An air conditioning apparatus according to a fifth aspect is the air conditioning apparatus according to the fourth aspect, wherein the control unit performs the opening adjustment by the second member in a state where the opening of the first valve port is equal to or less than a predetermined value during the first operation.

[0016] In this air conditioner, by using a two-stage expansion valve, the opening of the expansion valve is finely controlled in a small flow control region, so that the air conditioner can finely adjust the reheating effect when performing a reheat dehumidification operation.

[0017] The air conditioner of the sixth aspect is the air conditioner of any one of the first to fifth aspects, wherein the control unit further controls the refrigerant circuit to perform a second operation, in which the first heat exchanger functions as a condenser and the second and third heat exchangers function as evaporators. When performing the second operation, the control unit controls the expansion valve so that the refrigerant passing through the expansion valve is not decompressed, and performs the opening adjustment based on the first component and the second component.

[0018] In this air conditioning apparatus, by appropriately adjusting the opening degree of the expansion valve, it is possible to switch between cooling operation in which the second heat exchanger and the third heat exchanger function as evaporators and reheat dehumidification operation.

[0019] The air conditioning device of the seventh aspect is based on the air conditioning device of the sixth aspect, and the control unit adjusts the opening of the first component and the second component in such a manner that the humidity of the refrigerant sucked into the compressor when executing the second operation is greater than the humidity of the refrigerant sucked into the compressor when executing the first operation.

[0020] In this air conditioning apparatus, by appropriately adjusting the opening degree of the expansion valve, it is possible to switch between the cooling operation and the reheat dehumidification operation.

[0021] The air conditioning device of the eighth aspect is the air conditioning device described in any one of the first to seventh aspects, and further includes a fourth temperature sensor and a fifth temperature sensor. The fourth temperature sensor detects the temperature of the space where the second unit is installed. The fifth temperature sensor detects the temperature of the space where the first unit is installed. At the start of the first operation, the control unit adjusts the opening of the second component in such a way that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state based on the temperatures detected by the fourth temperature sensor and the fifth temperature sensor.

[0022] In this air conditioner, when the reheat dehumidification operation starts, the humidity state of the refrigerant in the third heat exchanger is estimated based on the room temperature and the outside air temperature, thereby controlling the opening of the expansion valve. Thus, when the reheat dehumidification operation is performed, the air conditioner can achieve an appropriate reheating effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic configuration diagram of an air conditioning device 1 according to one embodiment of the present disclosure.

[0024] Figure 2 It is a schematic cross-sectional view of the indoor expansion valve 32 .

[0025] Figure 3 : is a graph showing the flow rate characteristics of the indoor expansion valve 32 .

[0026] Figure 4 It is a control block diagram of the control unit 6.

[0027] Figure 5 This is a flowchart of an example of control executed by the control unit 6 during the reheat dehumidification operation.

[0028] Figure 6 This is a flowchart of an example of control executed by the control unit 6 during the reheat dehumidification operation. DETAILED DESCRIPTION

[0029] An air conditioning device 1 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0030] (1) Overall structure

[0031] The air conditioning device 1 performs indoor air conditioning of a building or the like as a target space by circulating a vapor compression refrigerant. Figure 1 As shown, the air conditioning device 1 mainly includes an outdoor unit 2, an indoor unit 3, a liquid refrigerant communication pipe 4, a gas refrigerant communication pipe 5, a control unit 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 connected in a ring shape through refrigerant piping to form a refrigerant circuit 100. The refrigerant circuit 100 is sealed with refrigerant. The control unit 6 realizes the refrigeration cycle by controlling the refrigerant circuit 100, thereby performing air conditioning operations such as heating operation, cooling operation, and reheat dehumidification operation.

[0032] (2) Detailed structure

[0033] (2-1) Outdoor unit

[0034] The outdoor unit 2 is installed outdoors, such as on the roof of a building or near the outer wall of a building. The outdoor unit 2 mainly includes a compressor 21, a four-way switching valve 23, an outdoor heat exchanger 24, an outdoor expansion valve 25, and an outdoor fan 26. Figure 1 As shown, the outdoor unit 2 may further include at least one of a discharge pipe temperature sensor 27 , an outdoor heat exchanger temperature sensor 28 , and an outdoor temperature sensor 29 , as necessary.

[0035] (2-1-1) Compressor

[0036] The compressor 21 sucks low-pressure refrigerant from the suction side 21a in the refrigerant circuit 100, compresses it to high pressure, and 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 positive displacement 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 control unit 6 via an inverter or the like.

[0037] (2-1-2) Four-way switching valve

[0038] The four-way switching valve 23 switches the flow direction of the refrigerant in the refrigerant circuit 100. The four-way switching valve 23 has a first valve port P1, a second valve port P2, a third valve port P3, and a fourth valve port P4. The four-way switching valve 23 is controlled by the control unit 6 in the first state ( Figure 1 The state shown by the dotted line) and the second state ( Figure 1 In the first state, the first valve port P1 is connected to the fourth valve port P4, and the second valve port P2 is connected to the third valve port P3. In the second state, the first valve port P1 is connected to the second valve port P2, and the third valve port P3 is connected to the fourth valve port P4.

[0039] The first valve port P1 is connected to the discharge side 21b of the compressor 21. The second valve port P2 is connected to the gas side 24b of the outdoor heat exchanger 24. The third valve port P3 is connected to the suction side 21a of the compressor 21. The fourth valve port P4 is connected to the gas refrigerant communication pipe 5. The discharge pipe 21c connects the discharge side 21b of the compressor 21 to the first valve port P1 of the four-way switching valve 23.

[0040] (2-1-3) Outdoor heat exchanger

[0041] The outdoor heat exchanger 24 performs heat exchange between the refrigerant in the outdoor heat exchanger 24 and the outdoor air in the refrigerant circuit 100. The liquid side 24a of the outdoor heat exchanger 24 is connected to the outdoor expansion valve 25. The gas side 24b of the outdoor heat exchanger 24 is connected to the second valve port P2 of the four-way switching valve 23.

[0042] (2-1-4) Outdoor expansion valve

[0043] The outdoor expansion valve 25 is an expansion mechanism for decompressing 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 24a of the outdoor heat exchanger 24. The outdoor expansion valve 25 is an electric expansion valve capable of adjusting the opening degree. The opening degree of the outdoor expansion valve 25 is controlled by the control unit 6.

[0044] (2-1-5) Outdoor fan

[0045] The outdoor fan 26 generates airflow and supplies outdoor air to the outdoor heat exchanger 24. The outdoor air is passed through the outdoor heat exchanger 24 by the outdoor fan 26, thereby promoting heat exchange between the refrigerant in the outdoor heat exchanger 24 and the outdoor air. The outdoor fan 26 is driven to rotate by the outdoor fan motor 26a. The air volume of the outdoor fan 26 is controlled by changing the rotation speed of the outdoor fan motor 26a by the control unit 6.

[0046] (2-1-6) Discharge pipe temperature sensor

[0047] The discharge pipe temperature sensor 27 is provided in the discharge pipe 21c. The discharge pipe temperature sensor 27 detects the temperature of the refrigerant discharged from the compressor 21 (discharge pipe temperature).

[0048] (2-1-7) Outdoor heat exchanger temperature sensor

[0049] 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.

[0050] (2-1-8) Outdoor temperature sensor

[0051] The outdoor temperature sensor 29 is provided at an air intake port of a casing (not shown) of the outdoor unit 2. The outdoor temperature sensor 29 detects the temperature of outdoor air flowing into the casing of the outdoor unit 2 (outdoor temperature).

[0052] (2-2) Indoor unit

[0053] The indoor unit 3 is installed in the indoor space as the target space. The indoor unit 3 mainly includes a first indoor heat exchanger 311, a second indoor heat exchanger 312, an indoor expansion valve 32 and an indoor fan 33. Figure 1 As shown, the indoor unit 3 may further include at least one of an indoor temperature sensor 34 and an indoor heat exchanger temperature sensor 36 as necessary.

[0054] (2-2-1) First Indoor Heat Exchanger and Second Indoor Heat Exchanger

[0055] The first indoor heat exchanger 311 performs heat exchange between the refrigerant in the first indoor heat exchanger 311 and the indoor air in the refrigerant circuit 100. 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.

[0056] The second indoor heat exchanger 312 performs heat exchange 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.

[0057] The first indoor heat exchanger 311 and the second indoor heat exchanger 312 are arranged in the flow path of the airflow generated by the indoor fan 33. In the flow direction of the airflow generated by the indoor fan 33, the first indoor heat exchanger 311 is arranged at a position downstream of the second indoor heat exchanger 312. In other words, with the help of the airflow generated by the indoor fan 33, the indoor air first exchanges heat with the refrigerant in the second indoor heat exchanger 312, and then exchanges heat with the refrigerant in the first indoor heat exchanger 311.

[0058] (2-2-2) Indoor expansion valve

[0059] The indoor expansion valve 32 is an expansion mechanism for decompressing 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 capable of adjusting the opening degree. The opening degree of the indoor expansion valve 32 is controlled by the control unit 6.

[0060] like Figure 2 As shown, the indoor expansion valve 32 mainly includes a valve chamber 321 , a main valve element 322 , a sub-valve element 323 , and a driving portion 324 .

[0061] The valve chamber 321 is a cylindrical member that accommodates the main valve element 322. The valve chamber 321 has a main communication hole 321a as an inlet of the fluid formed on the side surface thereof, and a main valve port 321b as an outlet of the fluid formed at one end thereof.

[0062] The main valve core 322 is a cylindrical component that is housed inside the valve chamber 321 and changes the opening of the main valve port 321b. The main valve core 322 has a secondary valve port 322a formed at one end as an outlet for the fluid. The main valve core 322 has an annular retainer 322b installed at the other end. The main valve core 322 has a secondary communication hole 322c formed on the side as an inlet for the fluid.

[0063] The auxiliary valve core 323 is a needle-shaped component that changes the opening of the auxiliary valve port 322a and lifts the main valve core 322. A portion of the auxiliary valve core 323 is inserted into the main valve core 322 from the opening of the retainer 322b. The auxiliary valve core 323 has a tapered portion 323a formed at the end portion on the side inserted into the main valve core 322, and the end portion on the side opposite to the tapered portion 323a is fixed to the drive unit 324. When the auxiliary valve core 323 is inserted into the main valve core 322, a flange-shaped protrusion 323b is formed on the side of the portion of the auxiliary valve core 323 that is closer to the tapered portion 323a than the retainer 322b.

[0064] The driving unit 324 drives the main valve core 322 and the auxiliary valve core 323 in the axial direction. The driving unit 324 controls the driving amount through the control signal output by the control unit 6, that is, the output pulse. In other words, the opening of the indoor expansion valve 32 is controlled by the control unit 6. The unit operation amount of the indoor expansion valve 32 is one pulse, and as the driving pulse output by the control unit 6 increases, the opening of the indoor expansion valve 32 increases.

[0065] Figure 3 The graph shown in FIG. 1 shows 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, that is, the flow rate characteristics. Figure 3 As shown, the flow characteristic of the indoor expansion valve 32 has two flow control domains consisting of a small flow control domain in which the change of the flow rate relative to the unit operation amount (unit drive pulse) is small and a large flow control domain in which the change of the flow rate relative to the unit operation amount is larger than that of the small flow control domain. The flow rate of the refrigerant in the large flow control domain is larger than that of the refrigerant in the small flow control domain. The opening degree (%) of the indoor expansion valve 32 refers to the percentage of the drive pulse relative to the drive pulse output by the control unit 6 to fully open the indoor expansion valve 32. In the air conditioning device 1, the drive pulse for fully opening the indoor expansion valve 32 is 500 pulses.

[0066] (2-2-3) Indoor fan

[0067] The indoor fan 33 generates airflow and supplies indoor air to the first indoor heat exchanger 311 and the second indoor heat exchanger 312. The indoor air passes through the second indoor heat exchanger 312 and the first indoor heat exchanger 311 in sequence by the indoor fan 33, thereby promoting heat exchange between the refrigerant in the first indoor heat exchanger 311 and the second indoor heat exchanger 312 and the indoor air. The indoor fan 33 is driven to rotate by the indoor fan motor 33a. The air volume of the indoor fan 33 is controlled by changing the rotation speed of the indoor fan motor 33a by the control unit 6.

[0068] (2-2-4) Indoor temperature sensor

[0069] The indoor temperature sensor 34 is provided at an air intake port of a casing (not shown) of the indoor unit 3. The indoor temperature sensor 34 detects the temperature of the indoor air flowing into the casing of the indoor unit 3 (indoor temperature).

[0070] (2-2-5) Indoor heat exchanger temperature sensor

[0071] The indoor heat exchanger temperature sensor 36 is provided in the second indoor pipe 32b connecting the indoor expansion valve 32 and the second indoor heat exchanger 312. The indoor heat exchanger temperature sensor 36 detects the temperature (evaporation 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.

[0072] (2-3) Control Unit

[0073] like Figure 4 As shown, the control unit 6 is connected to the compressor 21, the four-way switching valve 23, the outdoor expansion valve 25, the outdoor fan 26, the indoor expansion valve 32, the indoor fan 33 and the remote controller 7 in a manner capable of transmitting and receiving control signals. The control unit 6 is connected in a manner capable of receiving detection signals from 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 as needed.

[0074] The control unit 6 controls the refrigerant circuit 100 by controlling 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 .

[0075] The control unit 6 is typically a computer mainly including a control computing device and a storage device. The control computing device is a processor such as a CPU or a GPU. The control computing device reads a control program stored in the storage device and performs operation control according to the control program. The control computing device can write the calculation result to the storage device or read the information stored in the storage device according to the control program.

[0076] The control unit 6 may be 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 via a communication line capable of transmitting and receiving control signals to each other.

[0077] (2-4) Remote control

[0078] The remote controller 7 receives 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 sends the received data as a control signal to the control unit 6. When the control unit 6 receives the control signal, it records it in the storage device.

[0079] The remote controller 7 includes a display unit 71. The display unit 71 displays information such as the air-conditioning operation mode being executed, the target indoor temperature, the target indoor humidity, the indoor temperature, and the indoor humidity.

[0080] (3) Action

[0081] (3-1) Operation of indoor expansion valve

[0082] When the driving pulse output by the control unit 6 is 0 pulse, the main valve core 322 is seated in the valve chamber 321 and the main valve port 321b is closed, and the sub-valve core 323 is seated in the main valve core 322 and the sub-valve port 322a is closed. At this time, the opening of the indoor expansion valve 32 is 0% (= (0 pulse / 500 pulse) × 100). In addition, at this time, at the main valve port 321b, a small gap is formed between the valve chamber 321 and the main valve core 322 (not shown in the figure). Therefore, even if the 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 small amount of refrigerant flows in the indoor expansion valve 32.

[0083] When the control unit 6 increases the drive pulse from 0 pulses, the drive unit 324 moves the sub-valve core 323 in the axial direction away from the sub-valve port 322a. Before the drive pulse reaches 150 pulses, the main valve core 322 continues to be seated in the valve chamber 321, and only the sub-valve core 323 moves to change the opening of the sub-valve port 322a. When the sub-valve port 322a is opened, the refrigerant flows out through the flow path formed by the main communication hole 321a of the valve chamber 321, the sub-communication hole 322c of the main valve core 322, the sub-valve port 322a of the main valve core 322, and the main valve port 321b of the valve chamber 321. When the drive pulse reaches 150 pulses, the opening 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 becomes fully open. In the indoor expansion valve 32, the driving pulse changes from 0 pulses to 150 pulses, and the range in which the opening of the sub-valve port 322a is changed by the sub-valve core 323 becomes the small flow control region. In other words, the range in which the opening of the indoor expansion valve 32 is 0% or more and 30% or less (the first range) is the small flow control region.

[0084] When the control unit 6 further increases the drive pulse from 150 pulses, the protrusion 323b of the sub-valve core 323 contacts the retainer 322b of the main valve core 322, and the sub-valve core 323 lifts the main valve core 322. In other words, the drive unit 324 moves the sub-valve core 323 away from the main valve port 321b in the axial direction, so that the main valve core 322 moves away from the main valve port 321b. As a result, when the drive pulse exceeds 150 pulses, the main valve core 322 moves to change the opening of the main valve port 321b in the state where the sub-valve port 322a is fully opened. When the main valve port 321b is opened, the refrigerant flows out through the flow path directly flowing from the main connecting hole 321a to the main valve port 321b in addition to the above-mentioned flow path formed by the main connecting hole 321a, the sub-connecting hole 322c, the sub-valve port 322a and the main valve port 321b.

[0085] The control unit 6 can increase the drive pulse to 500 pulses. When the drive pulse reaches 500 pulses, the opening of the indoor expansion valve 32 is 100% (= (500 pulses / 500 pulses) × 100). At this time, the main valve port 321b and the auxiliary valve port 322a are both in a fully open state. In the indoor expansion valve 32, the drive pulse changes from 150 pulses to 500 pulses, and the range of changing the opening of the main valve port 321b with the help of the main valve core 322 becomes a large flow control domain. In other words, the range in which the opening of the indoor expansion valve 32 is greater than 30% and less than 100% is a large flow control domain.

[0086] (3-2) Air conditioning operation

[0087] The air conditioning operation of the air conditioning device 1 executed by the control unit 6, namely, the heating operation, the cooling operation, and the reheat dehumidification operation will be described. Figure 1 As shown, in the refrigerant circuit 100 of the air-conditioning device 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, and the second indoor heat exchanger 312 are connected in a ring shape.

[0088] (3-2-1) Heating operation

[0089] When the control unit 6 receives a control signal for starting the heating operation from the remote controller 7, the control unit 6 starts the heating operation of the air conditioner 1. During the heating operation, the control unit 6 switches the four-way switching valve 23 to the first state ( Figure 1 In addition, the control unit 6 makes the outdoor expansion valve 25 open to a degree corresponding to the target temperature received from the remote controller 7, and makes the indoor expansion valve 32 fully open or nearly fully open to operate the compressor 21. As a result, the outdoor heat exchanger 24 functions as an evaporator (heat absorber) of the refrigerant, and the first indoor heat exchanger 311 and the second indoor heat exchanger 312 function as condensers (radiators) of the refrigerant.

[0090] During the 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 condenses. As a result, the indoor air is heated and discharged indoors as conditioned air. After the condensed refrigerant is decompressed by passing through the outdoor expansion valve 25, it exchanges heat with the outdoor air supplied by the outdoor fan 26 in the outdoor heat exchanger 24 and evaporates. The refrigerant after passing through the outdoor heat exchanger 24 is sucked into the compressor 21 and compressed.

[0091] (3-2-2) Refrigeration operation

[0092] When the control unit 6 receives a control signal for starting the cooling operation (second operation) from the remote controller 7, the cooling operation of the air conditioner 1 is started. During the cooling operation, the control unit 6 switches the four-way switching valve 23 to the second state ( Figure 1 In addition, the control unit 6 makes the outdoor expansion valve 25 open to a degree corresponding to the target temperature received from the remote controller 7, and makes the indoor expansion valve 32 fully open or nearly fully open to operate the compressor 21. As a result, the outdoor heat exchanger 24 functions as a condenser (radiator) of the refrigerant, and the first indoor heat exchanger 311 and the second indoor heat exchanger 312 function as evaporators (heat absorbers) of the refrigerant.

[0093] During the 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 condenses. After the condensed refrigerant is decompressed by passing through the outdoor expansion valve 25, 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 and evaporates. As a result, the indoor air is cooled and discharged into the room as conditioned air. The refrigerant after passing through the first indoor heat exchanger 311 and the second indoor heat exchanger 312 is sucked into the compressor 21 and compressed.

[0094] (3-2-3) Reheat Dehumidification Operation

[0095] When the control unit 6 receives a control signal for starting the reheat dehumidification operation (first operation) from the remote controller 7, the control unit 6 starts the reheat dehumidification operation of the air conditioner 1. The reheat dehumidification operation is an air conditioning operation that dehumidifies the indoor air using the second indoor heat exchanger 312 and heats the dehumidified air using the first indoor heat exchanger 311. During the reheat dehumidification operation, the control unit 6 switches the four-way switching valve 23 to the second state ( Figure 1In addition, the controller 6 makes the outdoor expansion valve 25 fully open or nearly fully open, and makes the indoor expansion valve 32 open in accordance with the dehumidification load based on the target humidity received from the remote controller 7, so as to operate the compressor 21. Thus, the outdoor heat exchanger 24 and the first indoor heat exchanger 311 function as a condenser (radiator) of the refrigerant, and the second indoor heat exchanger 312 functions as an evaporator (heat absorber) of the refrigerant.

[0096] 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. The refrigerant condensed in the outdoor heat exchanger 24 passes through the outdoor expansion valve 25, and then exchanges heat with the indoor air supplied by the indoor fan 33 in the first indoor heat exchanger 311 and is condensed. The refrigerant condensed in the first indoor heat exchanger 311 is decompressed by the indoor expansion valve 32, and then evaporates by exchanging heat with the indoor air supplied by the indoor fan 33 in the second indoor heat exchanger 312. Thus, after the indoor air is dehumidified in the second indoor heat exchanger 312, it is heated in the first indoor heat exchanger 311, and the air that is dehumidified but the temperature drop is suppressed is discharged into the room as conditioned air. The refrigerant that has passed through the second indoor heat exchanger 312 is sucked into the compressor 21 and compressed.

[0097] (3-3) Control during reheat dehumidification operation

[0098] When performing the reheat dehumidification operation, the control unit 6 controls the indoor expansion valve 32 in a small flow control region in which the opening of the sub-valve port 322a is changed by the sub-valve core 323 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. In other words, when performing the reheat dehumidification operation, the control unit 6 moves the sub-valve core 323 to change the opening of the sub-valve port 322a, thereby adjusting the opening of the indoor expansion valve 32. When the state of the refrigerant at the outlet of the second indoor heat exchanger 312 is a humid state, the refrigerant discharged from the second indoor heat exchanger 312 is not superheated steam, and the refrigerant in the second indoor heat exchanger 312 becomes humid steam.

[0099] When performing the reheat dehumidification operation, the control unit 6 maintains the opening of the main valve port 321b at a state below a specified value. The specified value is 0% or a value substantially equal to 0%, in which case the main valve port 321b is closed by the main valve core 322. However, as described above, even when the main valve port 321b is closed, a small amount of refrigerant flows through the main valve port 321b because a small gap is formed between the valve chamber 321 and the main valve core 322.

[0100] The control unit 6 switches between the operation modes of different dehumidification capacities, namely, the first mode and the second mode, and performs reheat dehumidification operation. The dehumidification capacity of the first mode is lower than that 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, the first opening degree is set to such an opening degree that most of the refrigerant flowing into the second indoor heat exchanger 312 through the indoor expansion valve 32 evaporates near the indoor expansion valve 32 in the second indoor heat exchanger 312. In contrast, the second opening degree is set to such an opening degree that the refrigerant flowing into the second indoor heat exchanger 312 through the indoor expansion valve 32 evaporates in the entirety of the second indoor heat exchanger 312. Thus, in the reheat dehumidification operation when the indoor expansion valve 32 is at the second opening, the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 through the indoor expansion valve 32 is greater than when the indoor expansion valve 32 is at the first opening, so that the area where the second indoor heat exchanger 312 functions as an evaporator becomes larger, and a high dehumidification capacity is exerted. Figure 3 As shown, the first opening of the indoor expansion valve 32 is set to 5% (= (25 pulses / 500 pulses) × 100), and the second opening of the indoor expansion valve 32 is set to 30% (= (150 pulses / 500 pulses) × 100). The values ​​of the first opening and the second opening are not limited to Figure 3 The values ​​shown.

[0101] 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 the instruction from the user when executing the reheat dehumidification operation. Specifically, when the control unit 6 receives a control signal regarding the switch between the first mode and the second mode from the remote controller 7 when executing the reheat dehumidification operation, the control unit 6 sends the received control signal to the control unit 6. The control unit 6 that receives the control signal regarding the switch between the first mode and the second mode switches between the first mode and the second mode based on the received control signal. When an execution instruction of an air-conditioning operation (for example, a cooling operation) other than the reheat dehumidification operation or an operation stop instruction of the air-conditioning device 1 is received from the remote controller 7, the control unit 6 ends the reheat dehumidification operation.

[0102] Next, several specific examples of controlling the indoor expansion valve 32 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state when the reheat dehumidification operation is performed will be described.

[0103] (3-3-1) Control based on the opening degree of the indoor expansion valve

[0104] In this control, the control unit 6 maintains the opening of the indoor expansion valve 32 at a predetermined value or more in the small flow control region. As a result, the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 is sufficiently ensured. As a result, the control unit 6 estimates that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. The control unit 6 may, for example, maintain the opening of the indoor expansion valve 32 at the second opening, i.e., 30%.

[0105] (3-3-2) Control based on discharge pipe temperature

[0106] In this control, according to Figure 5 The control unit 6 performs the control according to the flowchart shown in the figure. First, the control unit 6 obtains the discharge pipe temperature detected by the discharge pipe temperature sensor 27 (step S11). Next, the control unit 6 determines whether the discharge pipe temperature is higher than the specified target discharge pipe temperature (step S12). When the discharge pipe temperature is higher than the target discharge pipe temperature, the control unit 6 infers that the second indoor heat exchanger 312 is in a dry state (a state in which superheated steam exists in the second indoor heat exchanger 312) (step S13). In this case, the control unit 6 increases the opening of the indoor expansion valve 32 in the small flow control region to increase the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 (step S14). As a result, the discharge pipe temperature decreases. When the specified time has passed, the control unit 6 obtains the discharge pipe temperature again (step S11) and determines whether the discharge pipe temperature is higher than the target discharge pipe temperature (step S12). When the discharge pipe temperature becomes lower than the target discharge pipe temperature, the control unit 6 infers that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 is in a humid state (step S15). After that, the control unit 6 determines whether the reheat dehumidification operation has been completed based on the execution instruction of the cooling operation, etc. (step S16). If the reheat dehumidification operation has not been completed, the process of controlling the opening of the indoor expansion valve 32 is executed again. Therefore, during the execution of the reheat dehumidification operation, the process of controlling the opening of the indoor expansion valve 32 based on the discharge pipe temperature is continuously executed.

[0107] In addition, the method by which the control unit 6 estimates whether 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 higher than the target discharge pipe temperature for a predetermined time.

[0108] (3-3-3) Control based on condensation temperature and evaporation temperature

[0109] In this control, according to Figure 6. First, the control unit 6 obtains 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 evaporation temperature of the refrigerant detected by the indoor heat exchanger temperature sensor 36 (step S21). Next, the control unit 6 calculates the target discharge pipe temperature that makes the state of the refrigerant at the outlet of the second indoor heat exchanger 312 a wet state based on the condensation temperature and the evaporation temperature (step S22). Next, the control unit 6 determines whether 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 control unit 6 infers that the second indoor heat exchanger 312 is in a dry state (step S24). In this case, the control unit 6 increases the opening of the indoor expansion valve 32 in the small flow control domain to increase the flow rate of the refrigerant flowing into the second indoor heat exchanger 312 (step S25). As a result, the discharge pipe temperature is reduced. When the specified time has passed, the control unit 6 obtains the discharge pipe temperature, the condensation temperature and the evaporation temperature again (step S21), calculates the target discharge pipe temperature (step S22), and determines whether the discharge pipe temperature is higher than the target discharge pipe temperature (step S23). When the discharge pipe temperature becomes lower than the target discharge pipe temperature, the control unit 6 infers that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 is in a humid state (step S26). Thereafter, the control unit 6 determines whether the reheat dehumidification operation has ended based on the execution instruction of the refrigeration operation, etc. (step S27). When the reheat dehumidification operation has not ended, the opening control process of the indoor expansion valve 32 is executed again. Therefore, during the execution of the reheat dehumidification operation, the opening control process of the indoor expansion valve 32 based on the condensation temperature and the evaporation temperature continues to be executed.

[0110] In addition, the method by which the control unit 6 calculates the target discharge pipe temperature based on the condensation temperature and the evaporation temperature, and the method by which the second indoor heat exchanger 312 is estimated to be in a dry state based on the target discharge pipe temperature and the discharge pipe temperature are not particularly limited. For example, the control unit 6 may substitute the condensation temperature and the evaporation temperature into a predetermined calculation formula to calculate the target discharge pipe temperature, or may pre-store a table recording the relationship between the condensation temperature and the evaporation temperature and the target discharge pipe temperature, and use the table to obtain the target discharge pipe temperature. In addition, the control unit 6 may estimate that the second indoor heat exchanger 312 is in a dry state when the discharge pipe temperature is higher than the target discharge pipe temperature for a predetermined time.

[0111] (4) Features

[0112] (4-1)

[0113] In the air conditioner 1, when performing the reheat dehumidification operation, 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 a humid state, and performs the opening adjustment based on the sub-valve core 323. When performing the reheat dehumidification operation, if the supercooling degree of the refrigerant at the outlet of the first indoor heat exchanger 311 becomes excessive and the condensation temperature becomes low, the reheating effect of the air dehumidified in the second indoor heat exchanger 312 heated in the first indoor heat exchanger 311 may be reduced. When the air conditioner 1 is in the reheat dehumidification operation, the opening of the indoor expansion valve 32 is adjusted according to the state of the refrigerant in the second indoor heat exchanger 312, thereby controlling the supercooling degree of the refrigerant at the outlet of the first indoor heat exchanger 311 and suppressing the excessive decrease in the condensation temperature. As a result, the air conditioner 1 can improve the reheating effect of the air in the first indoor heat exchanger 311.

[0114] (4-2)

[0115] In the air conditioner 1, when the control unit 6 performs the reheat dehumidification operation, in the small flow control area where the change of the flow rate relative to the unit operation amount of the indoor expansion valve 32 is small, the opening of the indoor expansion valve 32 is adjusted by moving the sub-valve core 323. Thus, 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 control unit 6 can finely control the reheating effect of the air in the first indoor heat exchanger 311. Thus, compared with the case where the opening is controlled throughout the flow rate characteristics of the indoor expansion valve 32 during the reheat dehumidification operation, the air conditioner 1 can more appropriately improve the reheating effect of the air in the first indoor heat exchanger 311.

[0116] (4-3)

[0117] In the air conditioning device 1, the control unit 6 may also control the 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 the comparison between the predetermined target discharge pipe temperature and the discharge pipe temperature, and controls the opening of the indoor expansion valve 32 in such a way that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. Thus, the air conditioning device 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.

[0118] (4-4)

[0119] In the air conditioner 1, the control unit 6 may also control the opening of the indoor expansion valve 32 based on 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 evaporation temperature of the refrigerant detected by the indoor heat exchanger temperature sensor 36. In this case, the control unit 6 estimates the state of the refrigerant in the second indoor heat exchanger 312 based on the comparison between the target discharge pipe temperature calculated from the condensation temperature and the evaporation temperature and the discharge pipe temperature, and controls the opening of the indoor expansion valve 32 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. Thus, 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.

[0120] (4-5)

[0121] In the air conditioner 1, the control unit 6 can easily switch between the reheat dehumidification operation and the cooling operation by appropriately adjusting the opening of the outdoor expansion valve 25 and the indoor expansion valve 32. Specifically, the control unit 6 can perform the reheat dehumidification operation by making the outdoor expansion valve 25 fully open or nearly fully open and the indoor expansion valve 32 open in the small flow control area. In addition, the control unit 6 can perform the cooling operation by making the outdoor expansion valve 25 open at a predetermined opening and the indoor expansion valve 32 open at a fully open or nearly fully open.

[0122] (5) Modification

[0123] (5-1) Modification A

[0124] During the reheat dehumidification operation, as long as the refrigerant is wet at the outlet of the second indoor heat exchanger 312, the superheat of the refrigerant sucked into the compressor 21 may be high to a certain extent. However, during the cooling operation, the superheat of the refrigerant sucked into the compressor 21 is preferably low. Therefore, the control unit 6 may also adjust the opening of the indoor expansion valve 32 in such a way that the humidity of the refrigerant sucked into the compressor 21 during the cooling operation is greater than the humidity of the refrigerant sucked into the compressor 21 during the reheat dehumidification operation. The humidity of the refrigerant refers to the weight ratio of the liquid refrigerant in the wet vapor of the refrigerant. When the control unit 6 performs the cooling operation, in the full flow control domain (small flow control domain and large flow control domain), the opening of the indoor expansion valve 32 is adjusted by moving the main valve core 322 and the sub-valve core 323. The air conditioning device 1 can appropriately switch between the cooling operation and the reheat dehumidification operation by appropriately adjusting the opening of the outdoor expansion valve 25 and the indoor expansion valve 32.

[0125] (5-2) Modification B

[0126] The control unit 6 may also adjust the opening of the indoor expansion valve 32 in the small flow control region based on the indoor temperature detected by the indoor temperature sensor 34 and the outdoor temperature detected by the outdoor temperature sensor 29 at the start of the reheat dehumidification operation so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. In this case, 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 at the start of the reheat dehumidification operation, and controls the opening of the indoor expansion valve 32 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. Thus, 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.

[0127] (5-3) Modification C

[0128] The control unit 6 may also estimate 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 when performing the reheat dehumidification operation, and control the opening degree of the indoor expansion valve 32 so that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 becomes a humid state. The evaporator outlet temperature is, for example, a temperature detected by a temperature sensor provided on the refrigerant piping near the outlet of the second indoor heat exchanger 312. The compressor suction temperature is, for example, a temperature detected by a temperature sensor provided on the refrigerant piping near the suction side of the compressor 21.

[0129] In this case, for example, when the evaporator outlet temperature or the compressor suction temperature is within a prescribed range, the control unit 6 presumes that the second indoor heat exchanger 312 is in a dry state, and increases the opening of the indoor expansion valve 32 in the small flow control region to increase the flow rate of the refrigerant flowing into the second indoor heat exchanger 312. In addition, when the evaporator outlet temperature or the compressor suction temperature deviates from the prescribed range, the control unit 6 presumes that the state of the refrigerant at the outlet of the second indoor heat exchanger 312 has become a wet state, and stops changing the opening of the indoor expansion valve 32.

[0130] Alternatively, the control unit 6 may calculate a target discharge pipe temperature based on the evaporator outlet temperature and the compressor suction temperature, and control the opening degree of the indoor expansion valve 32 based on the target discharge pipe temperature similarly to the embodiment.

[0131] (5-4) Modification D

[0132] The control unit 6 may adjust the opening degree of the outdoor expansion valve 25 based on the discharge pipe temperature when performing cooling operation or heating operation.

[0133] (5-5) Modification E

[0134] The remote controller 7 may display the type of operation (cooling operation, heating operation, and reheat dehumidification operation) being executed by the control unit 6 and the operation mode (first mode and second mode) of the reheat dehumidification operation on the display unit 71 .

[0135] (5-6) Modification F

[0136] The control unit 6 may automatically switch and execute the reheat dehumidification operation and the cooling operation based on the indoor humidity, for example. In this case, the control unit 6 obtains the indoor humidity from the humidity sensor that detects the humidity of the air flowing into the casing of the indoor unit 3.

[0137] (5-7) Modification G

[0138] In the air conditioner 1 of the embodiment, the control unit 6 switches between the first mode and the second mode, which are operation modes with different dehumidification capacities, and performs the reheat dehumidification operation. However, the number of operation modes that the control unit 6 can switch during the reheat dehumidification operation may be three or more. In this case, the opening degree of the indoor expansion valve 32 in each operation mode is set to be different from each other.

[0139] (5-8) Modification H

[0140] In the air conditioner 1 of the embodiment, the control unit 6 starts the reheat dehumidification 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 to execute when the reheat dehumidification operation starts.

[0141] For example, the control unit 6 may record information about which of the first mode and the second mode was executed in the storage device when the last reheat dehumidification operation ends, and refer to the information when the reheat dehumidification operation starts next to determine which of the first mode and the second mode is executed at the beginning of the reheat dehumidification operation.

[0142] In addition, the control unit 6 can also record information about which of the first mode and the second mode is generally executed in each time period in the storage device, and refer to the information when starting the reheat dehumidification operation to determine which of the first mode and the second mode is executed at the start of the reheat dehumidification operation.

[0143] -summary-

[0144] As mentioned above, although embodiment of this disclosure is described, it should be understood that various changes in form and detail can be made without departing from the meaning and scope of this disclosure described in the claims.

[0145] Description of symbols

[0146] 1 Air conditioning unit

[0147] 2Outdoor unit (first unit)

[0148] 3Indoor unit (second unit)

[0149] 6. Control Unit

[0150] 21Compressor

[0151] 21c discharge pipe

[0152] 24 Outdoor heat exchanger (first heat exchanger)

[0153] 27 discharge pipe temperature sensor (first temperature sensor)

[0154] 28 Outdoor heat exchanger temperature sensor (second temperature sensor)

[0155] 29 Outdoor temperature sensor (fifth temperature sensor)

[0156] 311 first indoor heat exchanger (second heat exchanger)

[0157] 312 Second indoor heat exchanger (third heat exchanger)

[0158] 32 Indoor expansion valve (expansion valve)

[0159] 321 valve chamber (first valve seat)

[0160] 321b Main valve port (first valve port)

[0161] 322 main valve core (first component)

[0162] 322a Auxiliary valve port (second valve port)

[0163] 323 auxiliary valve core (second component)

[0164] 34 Indoor temperature sensor (fourth temperature sensor)

[0165] 36 Indoor heat exchanger temperature sensor (third temperature sensor)

[0166] 100 Refrigerant circuit

[0167] Prior art literature

[0168] Patent Literature

[0169] Patent Document 1: Japanese Patent Application Publication No. 2020-34140

Claims

1. An air conditioning device (1), comprising: a first unit (2) having a compressor (21) and a first heat exchanger (24); a second unit (3) having a second heat exchanger (311), an expansion valve (32) and a third heat exchanger (312); a refrigerant circuit (100), which is formed by the compressor, the first heat exchanger, the second heat exchanger, the expansion valve and the third heat exchanger being connected in a ring shape for circulating the refrigerant; and a control unit (6) for controlling the refrigerant circuit to perform a first operation in which the first heat exchanger and the second heat exchanger are made to function as condensers and the third heat exchanger is made to function as an evaporator, The expansion valve comprises a first component (322) and a second component (323) for adjusting the opening degree of the expansion valve. The second component performs the opening adjustment when the flow rate of the refrigerant passing through the expansion valve is within a first range, The first component adjusts the opening degree when the flow rate of the refrigerant passing through the expansion valve is greater than the first range, When the first operation is performed, the control unit controls the expansion valve so that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state to perform the opening adjustment based on the second member. The control unit further controls the refrigerant circuit to perform a second operation in which the first heat exchanger is made to function as a condenser and the second heat exchanger and the third heat exchanger are made to function as evaporators. When the second operation is performed, the control unit controls the expansion valve so that the refrigerant passing through the expansion valve is not decompressed, and performs the opening degree adjustment by the first member and the second member.

2. The air conditioning device according to claim 1, wherein: The air conditioning device further comprises: a discharge pipe (21c) connected to the discharge side of the compressor and allowing the refrigerant compressed by the compressor to flow; and a first temperature sensor (27) for detecting the temperature of the discharge pipe, The control unit adjusts the opening degree of the second member so that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state when the first operation is performed based on the temperature detected by the first temperature sensor.

3. The air conditioning device according to claim 2, wherein: The air conditioning device further comprises: a second temperature sensor (28) for detecting a temperature of the first heat exchanger; and a third temperature sensor (36) for detecting the temperature of a pipe connecting the expansion valve and the third heat exchanger, The control unit calculates a target temperature of the discharge pipe based on the temperatures detected by the second temperature sensor and the third temperature sensor. The control unit adjusts the opening degree of the second member so that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state when the first operation is performed based on the target temperature and the temperature detected by the first temperature sensor.

4. The air conditioning device according to any one of claims 1 to 3, wherein: The expansion valve further comprises a first valve seat (321), wherein the first valve seat (321) forms a first valve port (321b) for the refrigerant to pass through. The first component forms a second valve port (322a) for the refrigerant to pass through, The control unit changes the opening of the first valve port by controlling the position of the first member, thereby performing the opening adjustment based on the first member. The control unit controls the position of the second member to change the opening of the second valve port, thereby performing the opening adjustment based on the second member.

5. The air conditioning device according to claim 4, wherein: The control unit performs the opening adjustment using the second member in a state where the opening of the first valve port is equal to or smaller than a predetermined value when the first operation is executed.

6. The air conditioning device according to any one of claims 1 to 3, wherein: The control unit adjusts the opening degrees of the first member and the second member so that the humidity of the refrigerant sucked into the compressor during the second operation is greater than the humidity of the refrigerant sucked into the compressor during the first operation.

7. The air conditioning device according to any one of claims 1 to 3, wherein: The air conditioning device further comprises: a fourth temperature sensor (34) for detecting the temperature of a space in which the second unit is installed; and a fifth temperature sensor (29) for detecting the temperature of the space in which the first unit is installed, When the first operation starts, the control unit adjusts the opening degree of the second member so that the state of the refrigerant at the outlet of the third heat exchanger becomes a humid state based on the temperatures detected by the fourth temperature sensor and the fifth temperature sensor.

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