EP4617576A1

EP4617576A1 - Ventilation device

Info

Publication number: EP4617576A1
Application number: EP25711586.5A
Authority: EP
Inventors: Hideyuki Sano; Yoshiteru Nouchi
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2024-01-31
Filing date: 2025-01-28
Publication date: 2025-09-17
Also published as: JP2025118552A; EP4617576A4; JP7759010B2; WO2025164599A1

Abstract

A ventilator capable of stable temperature adjustment by handling more heat load than is conventional is provided. The ventilator ventilates air in a target space. The ventilator includes a refrigerant circuit, a first fan, and a second fan. The refrigerant circuit is configured by a compressor, a first heat exchanger, and a second heat exchanger being connected, and is filled with a refrigerant. The first fan discharges outside air, which is air outside the target space, into the target space through the first heat exchanger. The second fan discharges air in the target space to the outside of the target space through the second heat exchanger. The refrigerant circuit is further connected to a third heat exchanger that performs heat exchange between the refrigerant and a heat medium other than the refrigerant.

Description

TECHNICAL FIELD

The present disclosure relates to a ventilator.

BACKGROUND ART

Patent Literature 1 ( JP 2023-051676 A ) discloses a ventilator including a refrigerant circuit that is configured by a compressor, a first heat exchanger, and a second heat exchanger being connected and has an interior through which refrigerant flows, an air supply fan that supplies outside air passing through the first heat exchanger to an indoor space, and an exhaust fan that exhausts indoor air through the second heat exchanger. The ventilator according to Patent Literature 1 uses the first heat exchanger to perform heat exchange between the heat recovered from outside air by the second heat exchanger and the supply air, to adjust the temperature of a space to be ventilated.

SUMMARY OF THE INVENTION

The ventilator disclosed in Patent Literature 1 handles the heat load with only two heat exchangers, and therefore there is a limit to the amount of heat load that can be handled, and in some cases, it is not possible to stably adjust the temperature.
The present disclosure provides a ventilator capable of stable temperature adjustment by handling more heat load than is conventional.

A ventilator according to a first aspect ventilates air in a target space. The ventilator includes a refrigerant circuit, a first fan, and a second fan. The refrigerant circuit is configured by a compressor, a first heat exchanger, and a second heat exchanger being connected, and is filled with a refrigerant. The first fan discharges outside air, which is air outside the target space, into the target space through the first heat exchanger. The second fan discharges air in the target space to the outside of the target space through the second heat exchanger. The refrigerant circuit is further connected to a third heat exchanger that performs heat exchange between the refrigerant and a heat medium other than the refrigerant.
In this ventilator, the third heat exchanger that performs heat exchange between the outside air and the refrigerant is connected to the refrigerant circuit, thereby allowing the third heat exchanger to function and assist the second heat exchanger in capacity. Therefore, this ventilator can handle more heat load than is conventional, and is capable of stable temperature adjustment.
A ventilator according to a second aspect is the ventilator according to the first aspect, further including a flow path adjustment mechanism. The flow path adjustment mechanism adjusts a flow path of the refrigerant flowing through the refrigerant circuit between a first state in which the refrigerant is restricted from flowing into the third heat exchanger and a second state in which the refrigerant is permitted to flow into the third heat exchanger.
This ventilator allows the flow path adjustment mechanism to adjust the flow path of the refrigerant between the state in which the refrigerant flows into the third heat exchanger and the state in which no refrigerant flows into the third heat exchanger. Therefore, with this ventilator, power consumption can be reduced as compared to the case where the third heat exchanger is always functioning.
A ventilator according to a third aspect is the ventilator according to the second aspect, further including a control unit that controls the flow path adjustment mechanism. The control unit determines whether the refrigerant in the refrigerant circuit is in a first refrigerant state on the basis of a pressure or temperature of the refrigerant in the refrigerant circuit, sets the flow path adjustment mechanism to the second state upon determining that the refrigerant in the refrigerant circuit is in the first refrigerant state, and sets the flow path adjustment mechanism to the first state upon determining that the refrigerant in the refrigerant circuit is not in the first refrigerant state.
In a ventilator that uses the first heat exchanger to perform heat exchange between the heat recovered from outside air by the second heat exchanger and the supply air, fluctuations in outside air temperature and indoor temperature make it difficult to handle the heat load using only the first heat exchanger and the second heat exchanger, and there are cases where stable temperature adjustment is not possible.
This ventilator allows the third heat exchanger to assist the first heat exchanger or the second heat exchanger in capacity when in the first refrigerant state. Therefore, this ventilator is capable of stable temperature adjustment even when the outside air temperature and the indoor temperature fluctuate.
A ventilator according to a fourth aspect is the ventilator according to the third aspect, further including a third fan that blows air to the third heat exchanger. The control unit determines whether the refrigerant in the refrigerant circuit is in the first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit. The control unit operates the third fan upon determining that the refrigerant in the refrigerant circuit is in the first refrigerant state, and stops the third fan upon determining that the refrigerant in the refrigerant circuit is not in the first refrigerant state.
This ventilator allows the third heat exchanger to further assist the first heat exchanger or the second heat exchanger in capacity when in the first refrigerant state. Therefore, this ventilator is capable of stable temperature adjustment even when the outside air temperature and the indoor temperature fluctuate.
A ventilator according to a fifth aspect is the ventilator according to any one of the first to fourth aspects, further including a third fan that blows air to the third heat exchanger. The third heat exchanger, the third fan, and the compressor are housed in a single housing.
In the ventilator, since the third heat exchanger, the third fan, and the compressor are housed in the single housing, the increase in the arrangement space for the ventilator is suppressed.
A ventilator according to a sixth aspect is the ventilator according to any one of the first to fifth aspects, in which the third heat exchanger is installed outside the target space.
If the third heat exchanger is installed in the target space, a duct for sending the outside air to the third heat exchanger is required. In this ventilator, the installation of the third heat exchanger outside the target space eliminates the need for duct installation, thereby preventing the structure of the ventilator from becoming complicated.
A ventilator according to a seventh aspect is the ventilator according to any one of the first to fifth aspects, further including a plurality of first units each having the first heat exchanger and the first fan, and a plurality of second units each having the second heat exchanger and the second fan.
The present ventilator can ventilate a plurality of target spaces.
A ventilator according to an eighth aspect is the ventilator according to any one of the first to seventh aspects, in which the heat medium is the outside air.
A ventilator according to a ninth aspect is the ventilator according to any one of the first to eighth aspects, in which the third heat exchanger functions as an evaporator when the second heat exchanger functions as an evaporator, and functions as a condenser when the second heat exchanger functions as a condenser.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a ventilator 1 according to a first embodiment.
FIG. 2 is a refrigerant circuit diagram of the ventilator 1.
FIG. 3 is a block diagram schematically illustrating a control unit 700 and each portion connected to the control unit 700.
FIG. 4 is a flow chart illustrating processing executed by the control unit 700.
FIG. 5 is a refrigerant circuit diagram before a third heat exchanger functional state.
FIG. 6 is a refrigerant circuit diagram during the third heat exchanger functional state.
FIG. 7 is a refrigerant circuit diagram during the third heat exchanger functional state when a first four-way switching valve 371 is in a second state.
FIG. 8A is a refrigerant circuit diagram of a compressor unit 300a of a ventilator 1a according to a second embodiment.
FIG. 8B is a refrigerant circuit diagram of an air supply unit 100, exhaust unit 200, and flow path switching unit 600a of the ventilator 1a.
FIG. 9 is a block diagram schematically illustrating a control unit 700a and each portion connected to the control unit 700a.
FIG. 10A is a refrigerant circuit diagram before the third heat exchanger functional state.
FIG. 10B is a refrigerant circuit diagram before the third heat exchanger functional state.
FIG. 11 is a refrigerant circuit diagram during the third heat exchanger functional state.
FIG. 12 is a refrigerant circuit diagram during the third heat exchanger functional state when a four-way switching valve 370a is in the second state.

DESCRIPTION OF EMBODIMENTS

(1) Overall Configuration

FIG. 1 is a schematic configuration diagram of a ventilator 1 according to a first embodiment. FIG. 2 is a refrigerant circuit diagram of the ventilator 1.
The ventilator 1 is installed in buildings such as buildings and factories, and ventilates the air in target spaces Sa, Sb, and Sc, which are spaces to be ventilated, contained in such buildings. The ventilator 1 includes air supply units 100a, 100b, and 100c, exhaust units 200a, 200b, and 200c, a compressor unit 300, a flow path switching unit 600, and a control unit 700.
The air supply unit 100a and the exhaust unit 200a form one pair 400a, and ventilate the target space Sa. The air supply unit 100b and the exhaust unit 200b form one pair 400b, and ventilate the target space Sb. The air supply unit 100c and the exhaust unit 200c form one pair 400c, and ventilate the target space Sc.
The air supply units 100a, 100b, and 100c have no structural differences from each other except that the target spaces Sa, Sb, and Sc to be ventilated are different. For this reason, hereinafter, when describing features that are common among the air supply units 100a, 100b, and 100c, the reference signs "a", "b", and "c" will not be used, and the air supply units 100a, 100b, and 100c will be described as "air supply unit 100". In addition, the exhaust units 200a, 200b, and 200c have no structural differences from each other except that the target spaces Sa, Sb, and Sc to be ventilated are different. For this reason, hereinafter, when describing features that are common among the exhaust units 200a, 200b, and 200c, the reference signs "a", "b", and "c" will not be used, and the exhaust units 200a, 200b, and 200c will be described as "exhaust unit 200". Furthermore, when describing features that are common among the pairs 400a, 400b, and 400c, the reference signs "a", "b", and "c" will not be used, and the pairs 400a, 400b, and 400c will be described as "pair 400".
As illustrated in FIG. 2, the air supply unit 100, the exhaust unit 200, the compressor unit 300, and the flow path switching unit 600 are connected via a liquid refrigerant communication pipe 510, a high-pressure gas refrigerant communication pipe 520, and a low-pressure gas refrigerant communication pipe 530 to constitute a refrigerant circuit 500. The refrigerant circuit 500 is filled with refrigerant. The refrigerant filled in the refrigerant circuit 500 circulates inside the refrigerant circuit 500 as a compressor 330, which will be described later, operates. The ventilator 1 performs vapor compression refrigeration cycle operation by circulating the refrigerant in the refrigerant circuit 500.
Although detailed operation will be described later, the ventilation operation executed by the ventilator 1 includes temperature adjustment operation in which each of the pairs 400 adjusts the temperature of supply air SA. The temperature adjustment operation includes cooling operation and heating operation. In the cooling operation, the air supply unit 100 cools the supply air SA with the heat recovered from return air RA by the exhaust unit 200. In the heating operation, the air supply unit 100 heats the supply air SA with the heat recovered from the return air RA by the exhaust unit 200. The ventilator 1 can perform cooling operation and heating operation individually for each of the pairs 400.
The ventilator 1 also causes a third heat exchanger 310 (described later) to function when the refrigerant in the refrigerant circuit 500 is in a first refrigerant state (described later) during the temperature adjustment operation. At this time, the third heat exchanger 310 assists a second heat exchanger 210 in the amount of heat exchange.

(2) Detailed Configuration

(2-1) Air Supply Unit 100

The air supply unit 100 has a first heat exchanger 110, a first fan 120, a first flow rate adjustment valve 130, and a sensor 140. The first heat exchanger 110, the first fan 120, the first flow rate adjustment valve 130, and the sensor 140 are housed in a first housing 101. The air supply unit 100 is an example of a first unit.
The air supply unit 100 is installed on a wall surface surrounding the target space S.

(2-1-1) First Heat Exchanger 110

The first heat exchanger 110 performs heat exchange between the refrigerant flowing through the first heat exchanger 110 and the supply air SA.
A first end 110a of the first heat exchanger 110 is connected to a first main liquid refrigerant pipe 611 (described later) of a first liquid refrigerant pipe 610. A second end 110b of the first heat exchanger 110 is connected to a first junction gas refrigerant pipe 623 (described later) of a first gas refrigerant pipe 620.

(2-1-2) First Fan 120

The first fan 120 discharges outside air OA as the supply air SA into the target space S through the first heat exchanger 110. The rotational speed (the number of revolutions) of the first fan 120 is controlled by the control unit 700.

(2-1-3) First Flow Rate Adjustment Valve 130

The first flow rate adjustment valve 130 adjusts the flow rate of the refrigerant in the first main liquid refrigerant pipe 611. The first flow rate adjustment valve 130 is provided at the first end 110a of the first heat exchanger 110.
The opening degree of the first flow rate adjustment valve 130 is controlled by the control unit 700.

(2-1-4) Sensor 140

The sensor 140 includes an outside air temperature sensor 141. The outside air temperature sensor 141 is, for example, a thermistor.
The outside air temperature sensor 141 detects a temperature To of the outside air OA. The outside air temperature sensor 141 is disposed in the air flow before the air passes through the first heat exchanger 110.
The sensor 140 may further include a supply air temperature sensor, a liquid-side refrigerant temperature sensor, and a gas-side refrigerant temperature sensor (all not shown). At least one of the supply air temperature sensor, the liquid-side refrigerant temperature sensor, and the gas-side refrigerant temperature sensor is, for example, a thermistor.
The supply air temperature sensor is disposed in the air flow after the air has passed through the first heat exchanger 110, and detects a temperature Ts of the supply air SA.
The liquid-side refrigerant temperature sensor is disposed at the first end 110a of the first heat exchanger 110, and detects the temperature of the refrigerant passing through the first end 110a of the first heat exchanger 110.
The gas-side refrigerant temperature sensor is disposed at the second end 110b of the first heat exchanger 110, and detects the temperature of the refrigerant passing through the second end 110b of the first heat exchanger 110.

(2-2) Exhaust Unit 200

The exhaust unit 200 has the second heat exchanger 210, a second fan 220, a second flow rate adjustment valve 230, and a sensor 240. The second heat exchanger 210, the second fan 220, the second flow rate adjustment valve 230, and the sensor 240 are housed in a second housing 201. The exhaust unit 200 is an example of a second unit.
The exhaust unit 200 is installed on a wall surface surrounding the target space S.

(2-2-1) Second Heat Exchanger 210

The second heat exchanger 210 performs heat exchange between the refrigerant flowing through the second heat exchanger 210 and the return air RA.
A first end 210a of the second heat exchanger 210 is connected to a second main liquid refrigerant pipe 641 (described later) of a second liquid refrigerant pipe 640. A second end 210b of the second heat exchanger 210 is connected to a second junction gas refrigerant pipe 653 (described later) of a second gas refrigerant pipe 650.

(2-2-2) Second Fan 220

The second fan 220 discharges the return air RA as exhaust air EA to the outside of the target space S through the second heat exchanger 210. The rotational speed of the second fan 220 is controlled by the control unit 700.

(2-2-3) Second Flow Rate Adjustment Valve 230

The second flow rate adjustment valve 230 adjusts the flow rate of the refrigerant in the second main liquid refrigerant pipe 231. The second flow rate adjustment valve 230 is provided at the first end 210a of the second heat exchanger 210.
The opening degree of the second flow rate adjustment valve 230 is controlled by the control unit 700.

(2-2-4) Sensor 240

The sensor 240 includes a carbon dioxide concentration sensor 241 and a return air temperature sensor 242. The return air temperature sensor 242 is a thermistor.
The carbon dioxide concentration sensor 241 detects the concentration of carbon dioxide contained in the return air RA. The carbon dioxide concentration sensor 241 is disposed in the air flow before the air passes through the second heat exchanger 210.
The return air temperature sensor 242 detects a temperature Tr of the return air RA. The return air temperature sensor 242 is disposed in the air flow before the air passes through the second heat exchanger 210.
The sensor 240 may further include a liquid-side refrigerant temperature sensor 243 and a gas-side refrigerant temperature sensor 244 (both not shown). At least one of the liquid-side refrigerant temperature sensor 243 and the gas-side refrigerant temperature sensor 244 is, for example, a thermistor.
The liquid-side refrigerant temperature sensor is disposed at the first end 210a of the second heat exchanger 210, and detects the temperature of the refrigerant passing through the first end 210a of the second heat exchanger 210.
The gas-side refrigerant temperature sensor is disposed at the second end 210b of the second heat exchanger 210, and detects the temperature of the refrigerant passing through the second end 210b of the second heat exchanger 210.

(2-3) Compressor Unit 300

The compressor unit 300 has the third heat exchanger 310, a third fan 320, the compressor 330, a connection pipe 340, a check valve 350, a third control valve 360, a four-way switching valve 370, and a sensor 380. The third heat exchanger 310, the third fan 320, the compressor 330, the connection pipe 340, the check valve 350, the third control valve 360, the four-way switching valve 370, and the sensor 380 are housed in a third housing 301.
The compressor unit 300 is installed outside the target space S (for example, outside a building, in the ceiling space of the building, or the like).

(2-3-1) Third Heat Exchanger 310

The third heat exchanger 310 performs heat exchange between the refrigerant flowing through the third heat exchanger 310 and the outside air OA. The outside air OA having passed through the third heat exchanger 310 is exhausted to the outside of the target space S. Since the compressor unit 300 is installed outside the target space S, the third heat exchanger 310 is also installed outside the target space S.
A first end 311a of the third heat exchanger 310 is connected to a first four-way switching valve 371 (described later) of the four-way switching valve 370. A second end 311b of the third heat exchanger 310 is connected to the liquid refrigerant communication pipe 510 via a third connection pipe 343.

(2-3-2) Third Fan 320

The third fan 320 blows the outside air OA to the third heat exchanger 310. The rotational speed of the third fan 320 is controlled by the control unit 700.

(2-3-3) Compressor 330

The compressor 330 sucks in the low-pressure refrigerant in the refrigerant circuit 500 from a suction pipe 331, compresses the refrigerant to a predetermined pressure, and then discharges the refrigerant as high-pressure refrigerant from a discharge pipe 332.
The suction pipe 331 is connected to the low-pressure gas refrigerant communication pipe 530.
The discharge pipe 332 is connected to the first four-way switching valve 371 (described later) of the four-way switching valve 370.
The operating capacity of the compressor 330 is controlled by the control unit 700. The compressor 330 is, for example, a compressor, the operating capacity of which can be changed through inverter control of a compressor motor.

(2-3-4) Connection Pipe 340

The connection pipe 340 includes a first connection pipe 341, a second connection pipe 342, and a third connection pipe 343.
The first connection pipe 341 has one end connected to a second four-way switching valve 372 (described later) of the four-way switching valve 370 and the other end connected to the high-pressure gas refrigerant communication pipe 520.
The second connection pipe 342 has one end connected to the first four-way switching valve 371 and the other end connected to the low-pressure gas refrigerant communication pipe 530 and the suction pipe 331.
The third connection pipe 343 is connected to the second end 311b of the third heat exchanger 310 and the other end is connected to the liquid refrigerant communication pipe 510.

(2-3-5) Check Valve 350

The check valve 350 prevents the refrigerant from flowing from the discharge pipe 332 into the compressor 330. The check valve 350 is provided in the portion of the discharge pipe 332 closer to the compressor 330 than the portion thereof which is connected to a third port 372c of the second four-way switching valve 372.

(2-3-6) Third Control Valve 360

The third control valve 360 adjusts the flow path of the refrigerant flowing through the refrigerant circuit 500 between a closed state in which the flow of the refrigerant into the third heat exchanger 310 is restricted and an open state in which the flow of the refrigerant into the third heat exchanger 310 is permitted. The third control valve 360 controls the flow of the refrigerant in the third connection pipe 343. The third control valve 360 is provided in the third connection pipe 343.
The third control valve 360 is controlled between the open state and the closed state by the control unit 700.
The third control valve 360 is an example of a flow path adjustment mechanism. The closed state is an example of a first state, and the open state is an example of a second state.

(2-3-7) Four-Way Switching Valve 370

The four-way switching valve 370 includes the first four-way switching valve 371 and the second four-way switching valve 372. The first four-way switching valve 371 and the second four-way switching valve 372 each function substantially as a three-way valve, with refrigerant flow at one port blocked, as illustrated in FIG. 2.
The first four-way switching valve 371 changes between the first state and the second state and switches the flow path of the refrigerant. The first four-way switching valve 371 has a first port 371a, a second port 371b, and a third port 371c. The first port 371a is connected to the discharge pipe 332 of the compressor 330. The second port 371b is connected to the first end 311a of the third heat exchanger 310. The third port 371c is connected to the low-pressure gas refrigerant communication pipe 530 via the second connection pipe 342.
The first four-way switching valve 371 allows communication between the first port 371a and the second port 371b in the first state (see the solid line of the first four-way switching valve 371 in FIG. 2), and allows communication between the second port 371b and the third port 371c in the second state (see the dotted line of the first four-way switching valve 371 in FIG. 2). The first four-way switching valve 371 is controlled by the control unit 700.
The second four-way switching valve 372 changes between the first state and the second state and switches the flow path of the refrigerant. The second four-way switching valve 372 has a first port 372a, a second port 372b, and the third port 372c. The first port 372a is connected to the suction pipe 331 of the compressor 330. The second port 372b is connected to the low-pressure gas refrigerant communication pipe 530 via the second connection pipe 342. The third port 372c is connected to the discharge pipe 332 of the compressor 330.
The second four-way switching valve 372 allows communication between the second port 372b and the third port 372c in the first state (see the solid line of the second four-way switching valve 372 in FIG. 2), and allows communication between the first port 372a and the second port 372b in the second state (see the dotted line of the second four-way switching valve 372 in FIG. 2). The second four-way switching valve 372 is controlled by the control unit 700.

(2-3-8) Sensor 380

The sensor 380 includes a suction pressure sensor 381 and a discharge pressure sensor 382.
The suction pressure sensor 381 detects a suction pressure Ps of the refrigerant in the suction pipe 331. The suction pressure sensor 381 is disposed in the suction pipe 331.
The discharge pressure sensor 382 detects a discharge pressure Pd of the refrigerant in discharge pipe 332. The discharge pressure sensor 382 is disposed in the discharge pipe 332.
The sensor 380 may further include an intake air temperature sensor, a discharge air temperature sensor, a liquid-side refrigerant temperature sensor, and a gas-side refrigerant temperature sensor (all not shown). At least one of the intake air temperature sensor, the discharge air temperature sensor, the liquid-side refrigerant temperature sensor, and the gas-side refrigerant temperature sensor is, for example, a thermistor.
The intake air temperature sensor detects the temperature of the air sucked in by the third fan 320. The intake air temperature sensor is disposed in the air flow before the air passes through the third heat exchanger 310.
The discharge air temperature sensor detects the temperature of the air passing through and discharged from the third heat exchanger 310. The discharge air temperature sensor is disposed in the air flow after the air has passed through the third heat exchanger 310.
The gas-side refrigerant temperature sensor detects the temperature of the refrigerant passing through the first end 311a of the third heat exchanger 310. The gas-side refrigerant temperature sensor is disposed at the first end 311a of the third heat exchanger 310.
The liquid-side refrigerant temperature sensor detects the temperature of the refrigerant passing through the second end 311b of the third heat exchanger 310. The liquid-side refrigerant temperature sensor is disposed at the second end 311b of the third heat exchanger 310.

(2-4) Flow Path Switching Unit 600

The flow path switching unit 600 switches the flow path of the refrigerant flowing through the refrigerant circuit 500. The flow path switching unit 600 has the first liquid refrigerant pipe 610, the first gas refrigerant pipe 620, a first control valve 630, the second liquid refrigerant pipe 640, the second gas refrigerant pipe 650, and a second control valve 660.
The first liquid refrigerant pipe 610, the first gas refrigerant pipe 620, the first control valve 630, the second liquid refrigerant pipe 640, the second gas refrigerant pipe 650, and the second control valve 660 are housed in a fourth housing 601.
As illustrated in FIG. 2, the flow path switching unit 600 has at least the same number of the first gas refrigerant pipes 620, first control valves 630, second liquid refrigerant pipes 640, second gas refrigerant pipes 650, and second control valves 660 as the number of the pairs 400.

(2-4-1) First Liquid Refrigerant Pipe 610

The first liquid refrigerant pipe 610 connects the liquid refrigerant communication pipe 510 to the air supply unit 100. The first liquid refrigerant pipe 610 has one end connected to the liquid refrigerant communication pipe 510 and the other end connected to the first end 110a of the first heat exchanger 110.

(2-4-2) First Gas Refrigerant Pipe 620

The first gas refrigerant pipe 620 connects the high-pressure gas refrigerant communication pipe 520 and the low-pressure gas refrigerant communication pipe 530 to the air supply unit 100. The first gas refrigerant pipe 620 includes a first high and low-pressure gas refrigerant pipe 621, a first low-pressure gas refrigerant pipe 622, and a first junction gas refrigerant pipe 623.
The first high and low-pressure gas refrigerant pipe 621 has one end connected to the high-pressure gas refrigerant communication pipe 520 and the other end connected to the first junction gas refrigerant pipe 623.
The first low-pressure gas refrigerant pipe 622 has one end connected to the low-pressure gas refrigerant communication pipe 530 and the other end connected to the first junction gas refrigerant pipe 623.
The first junction gas refrigerant pipe 623 has one end connected to the first high and low-pressure gas refrigerant pipe 621 and the first low-pressure gas refrigerant pipe 622 and the other end connected to the second end 110b of the first heat exchanger 110.

(2-4-3) First Control Valve 630

The first control valve 630 controls the flow of the refrigerant in the first gas refrigerant pipe 620. The first control valve 630 includes a first high-pressure gas refrigerant control valve 631 and a first low-pressure gas refrigerant control valve 632.
The first high-pressure gas refrigerant control valve 631 is provided in the first high and low-pressure gas refrigerant pipe 621 and controls the refrigerant flowing through the first high and low-pressure gas refrigerant pipe 621.
The first low-pressure gas refrigerant control valve 632 is provided in the first low-pressure gas refrigerant pipe 622 and controls the refrigerant flowing through the first low-pressure gas refrigerant pipe 622.
The first high-pressure gas refrigerant control valve 631 and the first low-pressure gas refrigerant control valve 632 are controlled between the open state and the closed state by the control unit 700.

(2-4-4) Second Liquid Refrigerant Pipe 640

The second liquid refrigerant pipe 640 connects the liquid refrigerant communication pipe 510 to the exhaust unit 200. The second liquid refrigerant pipe 640 has one end connected to the liquid refrigerant communication pipe 510 and the other end connected to the first end 210a of the second heat exchanger 210.

(2-4-5) Second Gas Refrigerant Pipe 650

The second gas refrigerant pipe 650 connects the high-pressure gas refrigerant communication pipe 520 and the low-pressure gas refrigerant communication pipe 530 to the exhaust unit 200. The second gas refrigerant pipe 650 includes a second high and low-pressure gas refrigerant pipe 651, a second low-pressure gas refrigerant pipe 652, and a second junction gas refrigerant pipe 653.
The second high and low-pressure gas refrigerant pipe 651 has one end connected to the high-pressure gas refrigerant communication pipe 520 and the other end connected to the second junction gas refrigerant pipe 653.
The second low-pressure gas refrigerant pipe 652 has one end connected to the low-pressure gas refrigerant communication pipe 530 and the other end connected to the second junction gas refrigerant pipe 653.
The second junction gas refrigerant pipe 653 has one end connected to the second high and low-pressure gas refrigerant pipe 651 and the second low-pressure gas refrigerant pipe 652 and the other end connected to the second end 210b of the second heat exchanger 210.

(2-4-6) Second Control Valve 660

The second control valve 660 controls the flow of the refrigerant in the second gas refrigerant pipe 650. The second control valve 660 includes a second high-pressure gas refrigerant control valve 661 and a second low-pressure gas refrigerant control valve 662.
The second high-pressure gas refrigerant control valve 661 is provided in the second high and low-pressure gas refrigerant pipe 651 and controls the refrigerant flowing through the second high and low-pressure gas refrigerant pipe 651.
The second low-pressure gas refrigerant control valve 662 is provided in the second low-pressure gas refrigerant pipe 652 and controls the refrigerant flowing through the second low-pressure gas refrigerant pipe 652.
The second high-pressure gas refrigerant control valve 661 and the second low-pressure gas refrigerant control valve 662 are controlled between the open state and the closed state by the control unit 700.

(2-5) Control Unit 700

The control unit 700 is electrically connected to the first fan 120, the first flow rate adjustment valve 130, the sensor 140, the second fan 220, the second flow rate adjustment valve 230, the sensor 240, the third fan 320, the compressor 330, the third control valve 360, the four-way switching valve 370 (the first four-way switching valve 371 and the second four-way switching valve 372), the sensor 380, the first control valve 630 (the first high-pressure gas refrigerant control valve 631 and the first low-pressure gas refrigerant control valve 632), and the second control valve 660 (the second high-pressure gas refrigerant control valve 661 and the second low-pressure gas refrigerant control valve 662) so as to be capable of transmitting and receiving control signals and the like. The control unit 700 is housed in the third housing 301.
The user can operate the control unit 700 via a controller (also referred to as a management terminal or the like; not shown) such as a remote controller. For example, the user can set a set temperature Tse of the target space S via a remote controller. Thus, the set temperature Tse is recorded in the storage device (described later) of the control unit 700. The remote controller may be provided for each pair 400.
FIG. 3 is a block diagram schematically illustrating the control unit 700 and each portion connected to the control unit 700.
The control unit 700 controls the third control valve 360 between the closed state and the open state. More specifically, the control unit 700 determines whether the refrigerant in the refrigerant circuit 500 is in a first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500, sets the third control valve 360 to the open state upon determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state, and sets the third control valve 360 to the closed state upon determining that the refrigerant in the refrigerant circuit 500 is not in the first refrigerant state. The closed state is an example of a first state, and the open state is an example of a second state.
In addition, the control unit 700 may control the third fan 320 together with the third control valve 360 on the basis of the determination of whether or not the refrigerant is in the first refrigerant state. Specifically, the control unit 700 may determine whether the refrigerant in the refrigerant circuit 500 is in the first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500, operate the third fan 320 upon determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state, and stop the third fan 320 upon determining that the refrigerant in the refrigerant circuit 500 is not in the first refrigerant state.
The control unit 700 is implemented by a computer. The control unit 700 includes a control arithmetic device and a storage device (both not shown). The control arithmetic device is a processor such as a CPU or a GPU. The control arithmetic device reads a program stored in the storage device and performs predetermined processing according to the program. Furthermore, the control arithmetic device writes an arithmetic result to the storage device and reads information stored in the storage device in accordance with the program.

(3) Operation of Ventilator 1

(3-1) Processing Flow Executed by Control Unit 700

FIG. 4 is a flow chart illustrating processing executed by the control unit 700.
When the power source (not shown) of the ventilator 1 is turned on, the control unit 700 starts execution of the following processing flow.
In step S100, the control unit 700 starts controlling the rotational speed of the first fan 120 and the second fan 220.
In the rotational speed control, the control unit 700 controls the rotational speed of the first fan 120 and the second fan 220 on the basis of the carbon dioxide concentration D detected by the carbon dioxide concentration sensor 241 for each of the target spaces Sa, Sb, and Sc. The control unit 700 may control the rotational speed of the first fan 120 and the second fan 220 for each pair 400 according to the fan speed step (fan tap) selected by the user or the like.
In step S110, the control unit 700 determines whether or not to execute temperature adjustment operation for each of the pairs 400a, 400b, and 400c. Upon determining that the temperature adjustment operation is to be executed for at least one pair 400 (Yes), the control unit 700 advances the processing to step S120, and upon determining that the temperature adjustment operation is not to be executed for all pairs 400 (No), the control unit 700 advances the processing to step S110. In other words, the control unit 700 repeats step S110 until determining that the temperature adjustment operation is to be executed for at least one pair 400.
The temperature adjustment operation includes cooling operation and heating operation. Whether the cooling operation or the heating operation is executed in temperature adjustment operation can be set for each pair 400. The setting of whether the cooling operation or the heating operation is executed in the temperature adjustment operation may be made by the user, or by the control unit 700 on the basis of conditions such as the temperature To of the outside air OA.
The control unit 700 determines whether or not to execute the temperature adjustment operation on the basis of the temperature To of the outside air OA and the temperature Tr of the return air RA.
Specifically, if the pair 400 is set to execute the cooling operation, the control unit 700 first acquires and compares the set temperature Tse set by the user using the remote controller and the temperature To detected by the outside air temperature sensor 141. The control unit 700 determines to execute the cooling operation if the temperature To is higher than the set temperature Tse, and determines not to execute the cooling operation if the temperature To is equal to or lower than the temperature Ts.
The control unit 700 acquires and compares the temperature To detected by the outside air temperature sensor 141 and the temperature Tr detected by the return air temperature sensor 242. Then the control unit 700 may determine to execute the cooling operation if the temperature To is higher than the temperature Tr, and may determine not to execute the cooling operation if the temperature To is equal to or lower than the temperature Tr.
If the pair 400 is set to execute the heating operation, the control unit 700 first acquires and compares the set temperature Tse set by the user using the remote controller and the temperature To detected by the outside air temperature sensor 141. The control unit 700 determines to execute the heating operation if the temperature To is lower than the set temperature Tse, and determines not to execute the heating operation if the temperature To is equal to or higher than the temperature Ts.
The control unit 700 acquires and compares the temperature To detected by the outside air temperature sensor 141 and the temperature Tr detected by the return air temperature sensor 242. Then the control unit 700 determines to execute the heating operation if the temperature To is lower than the temperature Tr, and determines not to execute the heating operation if the temperature To is equal to or higher than the temperature Tr.
In step S120, the control unit 700 stops controlling the rotational speed of the first fan 120 and the second fan 220 for the pair 400 determined to execute the temperature adjustment operation, then starts the temperature adjustment operation (specifically, the cooling operation or the heating operation), and advances the processing to step S130. Details of the cooling operation and the heating operation will be described later.
In step S130, the control unit 700 determines whether or not the refrigerant in the refrigerant circuit 500 is in the first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500.
Upon determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state (Yes), the control unit 700 advances the processing to step S140, and upon determining that the refrigerant in the refrigerant circuit 500 is not in the first refrigerant state (No), the control unit 700 advances the processing to step S130. In other words, the control unit 700 repeats step S130 until determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state.
The first refrigerant state is when the heat load of the first heat exchanger 110 or the heat load of the second heat exchanger 210 needs to be assisted. The control unit 700 determines that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state if an evaporation temperature Te of the refrigerant is lower than a predetermined temperature Tt1.
The evaporation temperature Te is obtained by converting the suction pressure Ps detected by the suction pressure sensor 381 into the saturation temperature of the refrigerant.
In step S140, the control unit 700 brings the refrigerant circuit 500 into a state where the third heat exchanger 310 is functioning (hereinafter referred to as "third heat exchanger functional state"), and advances the processing to step S150.
Details of the third heat exchanger functional state will be described later.
In step S150, the control unit 700 determines whether or not to terminate the third heat exchanger functional state. Upon determining that the third heat exchanger functional state is to be terminated (Yes), the control unit 700 advances the processing to step S160, and upon determining that the third heat exchanger functional state is not to be terminated (No), the control unit 700 advances the processing to step S150. In other words, the control unit 700 repeats step S150 until determining that the third heat exchanger functional state is to be terminated.
The control unit 700 determines whether to terminate the third heat exchanger functional state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500. Specifically, the control unit 700 determines to switch the third control valve 360 from the open state to the closed state if the evaporation temperature Te of the refrigerant is higher than a predetermined temperature Tt2.
The predetermined temperature Tt2 is set to a value at which the refrigerant in the refrigerant circuit 500 is predicted not to enter the first refrigerant state even if the third heat exchanger function state is terminated.
In step S160, the control unit 700 terminates the third heat exchanger functional state and advances the processing to step S170.
In step S170, the control unit 700 determines whether or not to terminate the temperature adjustment operation for the pair 400 on which the temperature adjustment operation is being executed. Upon determining that the temperature adjustment operation is to be terminated (Yes), the control unit 700 advances the processing to step S180, and upon determining that the temperature adjustment operation is not to be terminated (No), the control unit 700 advances the processing to step S170. In other words, the control unit 700 repeats step S170 until determining that the temperature adjustment operation is to be terminated.
In cases where the pair 400 is in the cooling operation: if the temperature To is equal to or lower than the set temperature Tse, the control unit 700 determines to terminate the cooling operation, which is the temperature adjustment operation; and if the temperature To is higher than the set temperature Tse, the control unit 700 determines not to terminate the cooling operation.
In cases where the pair 400 is in the heating operation: if the temperature To is equal to or higher than the set temperature Tse, the control unit 700 determines to terminate the heating operation, which is the temperature adjustment operation; and if the temperature To is lower than the set temperature Tse, the control unit 700 determines not to terminate the heating operation.
In step S180, the control unit 700 terminates the temperature adjustment operation and advances the processing to step S100.
Even during the execution of the processing of any step, the control unit 700 terminates the execution of this processing flow when the power source of the ventilator 1 is turned off.

(3-2) Temperature Adjustment Operation

FIG. 5 is a refrigerant circuit diagram before the third heat exchanger functional state. FIG. 6 is a refrigerant circuit diagram during the third heat exchanger functional state. In FIGS. 5 and 6, the direction in which the refrigerant flows is indicated by arrows. FIG. 5 illustrates, as an example, the ventilator 1 in which the pair 400a and the pair 400c perform the heating operation and the pair 400b performs the cooling operation.

(3-2-1) Compressor Unit 300

When the temperature adjustment operation is started, the control unit 700 starts the compressor 330, brings the third control valve 360 into the closed state, brings the first four-way switching valve 371 into the first state, and brings the second four-way switching valve 372 into the first state. At this time, the control unit 700 does not start (operate) the third fan 320.
As a result, the compressor 330 sucks in the refrigerant in the low-pressure gas refrigerant communication pipe 530 from the suction pipe 331 and discharges the refrigerant as high-pressure refrigerant from the discharge pipe 332. The refrigerant compressed to a high pressure by the compressor 330 passes through the discharge pipe 332, the check valve 350, the third port 372c of the second four-way switching valve 372, and the second port 372b of the second four-way switching valve 372 in this order, and flows into the high-pressure gas refrigerant communication pipe 520. At this time, since the third control valve 360 is in the closed state, the flow of the refrigerant into the third heat exchanger 310 is restricted.
The control unit 700 controls the rotational speed of the compressor 330 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperature, and the like.

(3-2-2) Flow Path Switching Unit 600, and Pair 400 of Air Supply Unit 100 and Exhaust Unit 200 That Perform Cooling Operation

For the pair 400 (pair 400b in FIG. 5) determined to execute the cooling operation, the control unit 700 closes the corresponding first high-pressure gas refrigerant control valve 631, opens the first low-pressure gas refrigerant control valve 632, opens the second high-pressure gas refrigerant control valve 661, and closes the second low-pressure gas refrigerant control valve 662. In addition, the control unit 700 controls the rotational speed of the first fan 120 and the second fan 220 and adjusts the opening degrees of the first flow rate adjustment valve 130 and the second flow rate adjustment valve 230 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperatures, and the like.
As a result, the high-pressure refrigerant flowing through the high-pressure gas refrigerant communication pipe 520 passes through the second high and low-pressure gas refrigerant pipe 651, the second junction gas refrigerant pipe 653, the second heat exchanger 210, and the second liquid refrigerant pipe 640 in this order, and flows into the liquid refrigerant communication pipe 510. At this time, the flow rate of the refrigerant passing through the second liquid refrigerant pipe 640 is adjusted by the second flow rate adjustment valve 230.
The refrigerant flowing into the liquid refrigerant communication pipe 510 passes through the first liquid refrigerant pipe 610, the first heat exchanger 110, the first junction gas refrigerant pipe 623, and the first low-pressure gas refrigerant pipe 622 in this order, and flows into the low-pressure gas refrigerant communication pipe 530. At this time, the flow rate of the refrigerant passing through the first liquid refrigerant pipe 610 is adjusted by the first flow rate adjustment valve 130.
With the refrigerant flowing in this manner, the first heat exchanger 110 functions as an evaporator for the refrigerant, and the second heat exchanger 210 functions as a condenser for the refrigerant. As a result, the air supply unit 100 cools the supply air SA blown by the first fan 120 in the first heat exchanger 110 and then discharges the cooled air into the target space S. In addition, the exhaust unit 200 heats the return air RA blown by the second fan 220 in the second heat exchanger 210 and then discharges the heated air to the outside of the target space S as the exhaust air EA. The heating of the return air RA by the exhaust unit 200 corresponds to heat recovery from the return air RA.

(3-2-3) Flow Path Switching Unit 600, and Pair 400 of Air Supply Unit 100 and Exhaust Unit 200 That Perform Heating Operation

For the pairs 400 (pair 400a and pair 400c in FIG. 5) determined to execute the heating operation, the control unit 700 opens the corresponding the first high-pressure gas refrigerant control valve 631, closes the first low-pressure gas refrigerant control valve 632, closes the second high-pressure gas refrigerant control valve 661, and opens the second low-pressure gas refrigerant control valve 662. In addition, the control unit 700 controls the rotational speed of the first fan 120 and the second fan 220 and adjusts the opening degrees of the first flow rate adjustment valve 130 and the second flow rate adjustment valve 230 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperatures, and the like.
As a result, the high-pressure refrigerant flowing through the high-pressure gas refrigerant communication pipe 520 passes through the first high and low-pressure gas refrigerant pipe 621, the first junction gas refrigerant pipe 623, the first heat exchanger 110, and the first liquid refrigerant pipe 610 in this order, and flows into the liquid refrigerant communication pipe 510. At this time, the flow rate of the refrigerant passing through the first liquid refrigerant pipe 610 is adjusted by the first flow rate adjustment valve 130.
The refrigerant flowing into the liquid refrigerant communication pipe 510 passes through the second liquid refrigerant pipe 640, the second heat exchanger 210, the second junction gas refrigerant pipe 653, and the second low-pressure gas refrigerant pipe 652 in this order, and flows into the low-pressure gas refrigerant communication pipe 530. At this time, the flow rate of the refrigerant passing through the second liquid refrigerant pipe 640 is adjusted by the second flow rate adjustment valve 230.
With the refrigerant flowing in this manner, the first heat exchanger 110 functions as a condenser for the refrigerant, and the second heat exchanger 210 functions as an evaporator for the refrigerant. As a result, the air supply unit 100 heats the supply air SA blown by the first fan 120 in the first heat exchanger 110 and then discharges the heated air into the target space S. In addition, the exhaust unit 200 cools the return air RA blown by the second fan 220 in the second heat exchanger 210 and then discharges the cooled air to the outside of the target space S as the exhaust air EA. The cooling of the return air RA by the exhaust unit 200 corresponds to heat recovery from the return air RA.

(3-2-4) Pair 400 of Air Supply Unit 100 and Exhaust Unit 200 That Do Not Perform Temperature Adjustment Operation

Although not shown, the control unit 700 closes all of the first high-pressure gas refrigerant control valve 631, the first low-pressure gas refrigerant control valve 632, the second high-pressure gas refrigerant control valve 661, and the second low-pressure gas refrigerant control valve 662 for the pair 400 determined not to execute the temperature adjustment operation.
Thus, the refrigerant flowing through the liquid refrigerant communication pipe 510, the high-pressure gas refrigerant communication pipe 520, and the low-pressure gas refrigerant communication pipe 530 is restricted from flowing into the air supply unit 100 and the exhaust unit 200. As a result, the first heat exchanger 110 and the second heat exchanger 210 are restricted from functioning as heat exchangers.

(3-2-5) Compressor Unit 300 during Third Heat Exchanger Functional State

Upon determining to bring the refrigerant circuit 500 into the third heat exchanger functional state, the control unit 700 switches the third control valve 360, which is in a closed state, to the open state, and operates the stopped third fan 320 to start controlling the rotational speed. When the third control valve 360 is open, some of the refrigerant flowing through the discharge pipe 332 passes through the first port 371a of the first four-way switching valve 371, the second port 371b of the first four-way switching valve 371, the third heat exchanger 310, and the third control valve 360 in this order, and flows into the liquid refrigerant communication pipe 510. At this time, the control unit 700 starts controlling the rotational speed of the third fan 320 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperature, and the like.
With the refrigerant flowing in this manner, the third heat exchanger 310 functions as a condenser for the refrigerant. As a result, even if the heat load of the first heat exchanger 110 functioning as an evaporator increases due to fluctuations in the outside air OA and the return air RA, the third heat exchanger 310 compensates for the capacity of the second heat exchanger 210 functioning as a condenser. Therefore, the ventilator 1 is capable of stable temperature adjustment.

(4) Modifications

(4-1) 1A

The control unit 700 may bring the refrigerant circuit 500 into the third heat exchanger functional state when the first four-way switching valve 371 is in the second state. FIG. 7 is a refrigerant circuit diagram during the third heat exchanger functional state when the first four-way switching valve 371 is in the second state.
In this case, when the third control valve 360 is open, the compressor 330 sucks in the refrigerant in the liquid refrigerant communication pipe 510 from the suction pipe 331 through the third control valve 360, the third heat exchanger 310, the second port 371b of the first four-way switching valve 371, the third port 371c of the first four-way switching valve 371, and the second connection pipe 342, and discharges the refrigerant as high-pressure refrigerant from the discharge pipe 332. Hereinafter, the refrigerant discharged from the compressor 330 flows through the refrigerant circuit 500 in the same manner as in the first embodiment, and thus a detailed description thereof will be omitted.
With the refrigerant flowing in this manner, the third heat exchanger 310 functions as an evaporator for the refrigerant. As a result, even if the heat load of the first heat exchanger 110 functioning as a condenser increases due to fluctuations in the outside air OA and the return air RA, the third heat exchanger 310 compensates for the capacity of the second heat exchanger 210 functioning as an evaporator. Therefore, the ventilator 1 is capable of stable temperature adjustment.

(4-2) Modification 1B

The number of the pairs 400 may be one, two, four or more. In addition, a plurality of pairs 400 may ventilate one target space S. Furthermore, the number of the air supply units 100 and exhaust units 200 that ventilate one target space S does not have to be the same.
If the number of pairs 400 is one, the control unit 700 causes the third heat exchanger 310 to function as an evaporator when the second heat exchanger 210 functions as an evaporator, and causes the third heat exchanger 310 to function as a condenser when the second heat exchanger 210 functions as a condenser.

(4-3) Modification 1C

The first heat exchanger 110, first fan 120, first flow rate adjustment valve 130, and sensor 140 of the air supply unit 100 need not be housed in a single housing. For example, the first heat exchanger 110 and the first fan 120 may be installed, via a duct or the like, in a place such as a machine chamber away from the target space separately from other devices.
Similarly, the second heat exchanger 210, second fan 220, second flow rate adjustment valve 230, and sensor 240 of the exhaust unit 200 do not have to be housed in a single housing. The third heat exchanger 310, third fan 320, compressor 330, connection pipe 340, check valve 350, third control valve 360, four-way switching valve 370, and sensor 380 of the compressor unit 300 also do not have to be housed in a single housing. The first liquid refrigerant pipe 610, first gas refrigerant pipe 620, first control valve 630, second liquid refrigerant pipe 640, second gas refrigerant pipe 650, and second control valve 660 of the flow path switching unit 600 also do not have to be housed in a single housing.

(4-4) Modification 1D

The control unit 700 may be implemented by a plurality of control units individually provided in the air supply unit 100, the exhaust unit 200, the flow path switching unit 600, and the compressor unit 300. In this case, the respective control units may be electrically connected to each other so as to be capable of transmitting and receiving control signals and the like, and may cooperate with each other to implement each operation. In addition, one of the plurality of electrically connected control units may collectively control the other control units.

(4-5) Modification 1E

The control unit 700 may be implemented by a server providing cloud computing services, which is connected to the air supply unit 100, the exhaust unit 200, the flow path switching unit 600, and the compressor unit 300 via a network.

(4-6) Modification 1F

In the third heat exchanger 310, the heat medium with which the refrigerant exchanges heat is not limited to air outside the building. For example, in the third heat exchanger 310, the heat medium with which the refrigerant exchanges heat may be air in a room in which the pair 400 is not installed (in other words, other than the target space S).
In addition, in the third heat exchanger 310, the heat medium with which the refrigerant exchanges heat may be water flowing through a water circuit not illustrated. In this case, the third heat exchanger 310 has a refrigerant flow path connected to the refrigerant circuit 500 and a water flow path connected to the water circuit, and performs heat exchange between the refrigerant flowing in the refrigerant flow path and the water flowing in the water flow path.

(4-7) Modification 1G

The ventilator 1 may be capable of ventilation-only operation without heat recovery. For example, the ventilator 1 may only ventilate the target space S without heat recovery by controlling the first fan 120 and the second fan 220 without starting the compressor 330.

(4-8) Modification 1H

The control unit 700 may bring the refrigerant circuit 500 into the third heat exchanger functional state in the following cases, separately from the case where the heat load of the first heat exchanger 110 or the heat load of the second heat exchanger 210 needs to be assisted.
The control unit 700 may bring the refrigerant circuit 500 into the third heat exchanger functional state if the pressure of the refrigerant can exceed the design pressure of the refrigerant circuit 500. In this case, the control unit 700 brings the refrigerant circuit 500 into the third heat exchanger functional state when the discharge pressure Pd is higher than a predetermined pressure Pt1.
The control unit 700 may bring the refrigerant circuit 500 into the third heat exchanger functional state upon determining that the capacity of the first heat exchanger 110 and the second heat exchanger 210 is not sufficient even if the refrigerant in the refrigerant circuit 500 is not in the first refrigerant state. In this case, the control unit 700 acquires the temperature of the refrigerant passing through the first end 210a of the second heat exchanger 210 as detected by the liquid-side refrigerant temperature sensor for the pair 400 that performs the cooling operation, and the temperature of the refrigerant passing through the second end 210b of the second heat exchanger 210 as detected by the gas-side refrigerant temperature sensor for the pair 400 that performs the heating operation. Then the control unit 700 determines whether or not to bring the refrigerant circuit 500 into the third heat exchanger functional state on the basis of the difference between the acquired temperature and a predetermined temperature (which may be the same or different between the cooling operation and the heating operation).
The control unit 700 may bring the refrigerant circuit 500 into the third heat exchanger functional state when the load on the compressor 330 increases and the temperature of a sliding portion (not shown) inside the compressor 330 may exceed an allowable value. In this case, the control unit 700 brings the refrigerant circuit 500 into the third heat exchanger functional state when a condensation temperature Tc of the refrigerant is higher than a predetermined temperature Tt3. The condensation temperature Tc is obtained by converting the discharge pressure Pd detected by the discharge pressure sensor 382 into the saturation temperature of the refrigerant.
If there is a risk of condensation water freezing on the surface of second heat exchanger 210 in any one of the pairs 400, the control unit 700 may bring the refrigerant circuit 500 into the third heat exchanger functional state. In this case, in any one of the pairs 400, if the suction pressure Ps is lower than a predetermined pressure, or if the temperature of the refrigerant passing through the first end 210a of the second heat exchanger 210 as detected by the liquid-side refrigerant temperature sensor is lower than the predetermined temperature, the control unit 700 brings the refrigerant circuit 500 into the third heat exchanger functional state.

(4-9) Modification 1I

On the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500, the control unit 700 may determine whether or not to bring the refrigerant circuit 500 into the third heat exchanger functional state, in consideration of the power consumption of the compressor 330 and the third fan 320 in addition to whether or not the refrigerant in the refrigerant circuit 500 is in the first refrigerant state.
Specifically, after determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500 (when "Yes" is determined in S130), the control unit 700 determines whether or not power consumption Pw1 of the third fan 320, which increases as a result of the refrigerant circuit 500 being in the third heat exchanger functional state, exceeds current power consumption Pw2 of the compressor 330 when the refrigerant circuit 500 is not in the third heat exchanger functional state. When the power consumption Pw1 exceeds the power consumption Pw2, the control unit 700 determines that the refrigerant circuit 500 is in the third heat exchanger functional state.
Thus, it is possible to prevent the power consumption of the entire ventilator 1 from increasing as a result of starting the third fan 320 to cause the third heat exchanger 310 to function.

(4-10) Modification 1J

In the ventilator 1, the adjustment of the inflow of the refrigerant into the third heat exchanger 310 (in other words, the flow path adjustment mechanism) is achieved by the third control valve 360, but the adjustment of the inflow of refrigerant into the third heat exchanger 310 may be achieved by using a four-way switching valve and/or a control valve.
For example, a bypass valve that bypasses the third connection pipe 343 and the first end 311a of the third heat exchanger 310 may be provided. In this case, when the refrigerant in the refrigerant circuit 500 is in the first refrigerant state, the bypass valve in the first state that does not bypass the third connection pipe 343 and the first end 311a is set to the second state that bypasses the third connection pipe 343 and the first end 311a.

(5) Features

(5-1)

The ventilator 1 ventilates air in the target space S. The ventilator 1 includes the refrigerant circuit 500, the first fan 120, and the second fan 220. The refrigerant circuit 500 is configured by the compressor 330, the first heat exchanger 110, and the second heat exchanger 210 being connected, and is filled with a refrigerant. The first fan 120 discharges the outside air OA, which is the air outside the target space S, into the target space S through the first heat exchanger 110. The second fan 220 discharges air in the target space S to the outside of the target space S through the second heat exchanger 210. The refrigerant circuit 500 is further connected to the third heat exchanger 310 that performs heat exchange between the refrigerant and a heat medium (such as outside air OA) other than the refrigerant.
In the ventilator 1, the third heat exchanger 310 that performs heat exchange between the refrigerant and the heat medium other than the refrigerant is connected to the refrigerant circuit 500, thereby allowing the third heat exchanger 310 to function and assist the second heat exchanger 210 in capacity. Therefore, the ventilator 1 can handle more heat load than is conventional, and is capable of stable temperature adjustment.

(5-2)

The ventilator 1 further includes the third control valve 360 (flow path adjustment mechanism). The third control valve 360 adjusts the flow path of the refrigerant flowing through the refrigerant circuit 500 between the closed state (first state) in which the refrigerant is restricted from flowing into the third heat exchanger 310 and the open state (second state) in which the refrigerant is permitted to flow into the third heat exchanger 310.
The ventilator 1 allows the third control valve 360 to adjust the flow path of the refrigerant between the state in which the refrigerant flows into the third heat exchanger 310 and the state in which no refrigerant flows into the third heat exchanger 310. Therefore, with the ventilator 1, power consumption can be reduced as compared to the case where the third heat exchanger 310 is always functioning.

(5-3)

The ventilator 1 further includes the control unit 700 that controls the third control valve 360. The control unit 700 determines whether the refrigerant in the refrigerant circuit 500 is in the first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500, sets the third control valve 360 to the closed state upon determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state, and sets the third control valve 360 to the open state upon determining that the refrigerant in the refrigerant circuit 500 is not in the first refrigerant state.
In a ventilator that uses the first heat exchanger to perform heat exchange between the heat recovered from outside air by the second heat exchanger and the supply air, fluctuations in outside air temperature and indoor temperature make it difficult to handle the heat load using only the first heat exchanger and the second heat exchanger, and there are cases where stable temperature adjustment is not possible.
The ventilator 1 allows the third heat exchanger 310 to assist the first heat exchanger 110 or the second heat exchanger 210 in the capacity when in the first refrigerant state. Therefore, the ventilator 1 is capable of stable temperature adjustment even when the outside air temperature and the indoor temperature fluctuate.

(5-4)

The ventilator 1 further includes the third fan 320 that blows air to the third heat exchanger 310. The control unit 700 determines whether the refrigerant in the refrigerant circuit 500 is in the first refrigerant state on the basis of the pressure or temperature of the refrigerant in the refrigerant circuit 500, operates the third fan 320 upon determining that the refrigerant in the refrigerant circuit 500 is in the first refrigerant state, and stops the third fan 320 upon determining that the refrigerant in the refrigerant circuit 500 is not in the first refrigerant state.
The ventilator 1 allows the third heat exchanger 310 to further assist the first heat exchanger 110 or the second heat exchanger 210 in the capacity when in the first refrigerant state. Therefore, the ventilator 1 is capable of stable temperature adjustment even when the outside air temperature and the indoor temperature fluctuate.

(5-5)

The ventilator 1 further includes the third fan 320 that blows air to the third heat exchanger 310.
The third heat exchanger 310, the third fan 320, and the compressor 330 are housed in the single third housing 301.
Since the third heat exchanger 310, the third fan 320, and the compressor 330 are housed in the single third housing 301, the increase in the arrangement space for the ventilator 1 is suppressed.

(5-6)

The third heat exchanger 310 is installed outside the target space S.
If the third heat exchanger 310 is installed in the target space S, a duct for sending the outside air OA to the third heat exchanger 310 is required. The installation of the third heat exchanger 310 outside the target space S eliminates the need for duct installation, thereby preventing the structure of the ventilator 1 from becoming complicated.

(5-7)

The ventilator 1 includes: the plurality of air supply units 100 (first units) each having the first heat exchanger 110 and the first fan 120; and the plurality of exhaust units 200 (second units) each having the second heat exchanger 210 and the second fan 220.
The ventilator 1 can ventilate a plurality of target spaces. In addition, when ventilating a plurality of target spaces with the ventilator 1, the pair 400 of the air supply unit 100 and the exhaust unit 200 can be installed for each of the target spaces. Therefore, with the ventilator 1, the duct length is prevented from becoming long, compared to a case where a ventilator, in which an air supply heat exchanger, an air supply fan, an exhaust heat exchanger, and an exhaust fan are housed in a single unit, is connected to a plurality of target spaces via ducts. Furthermore, the ventilator 1 can have different heat exchange capacities for each of the 400 pairs.

(5-8)

The heat medium other than the refrigerant is the outside air OA.

(5-9)

The third heat exchanger 310 functions as an evaporator when the second heat exchanger 210 functions as an evaporator, and functions as a condenser when the second heat exchanger 210 functions as a condenser.

(1) Overall Configuration

Next, a ventilator 1a according to a second embodiment will be described. Hereinafter, differences between the ventilator 1 and the ventilator 1a will be mainly described, and description of the same or corresponding features and known technologies may be omitted. FIG. 8A is a refrigerant circuit diagram of a compressor unit 300a of the ventilator 1a according to the second embodiment. FIG. 8B is a refrigerant circuit diagram of the air supply unit 100, the exhaust unit 200, and a flow path switching unit 600a of the ventilator 1a.
The main differences between the ventilator 1 and the ventilator 1a are that the ventilator 1a includes the compressor unit 300a instead of the compressor unit 300, and includes the flow path switching unit 600a instead of the flow path switching unit 600, and a low-pressure refrigerant communication pipe 540 and a high-pressure refrigerant communication pipe 550 connect the compressor unit 300a and the flow path switching unit 600a to constitute a refrigerant circuit 500a.

(2) Detailed Configuration

(2-1) Compressor Unit 300a

The compressor unit 300a has a third heat exchanger 310a, the third fan 320, a compressor 330a, a connection pipe 340a, a check valve 350a, a third control valve 360a, a fourth control valve 390, a four-way switching valve 370a, and the sensor 380.

(2-1-1) Third Heat Exchanger 310a

The third heat exchanger 310a performs heat exchange between the refrigerant flowing through the third heat exchanger 310 and the outside air OA. Since the compressor unit 300 is installed outside the target space S, the third heat exchanger 310a is also installed outside the target space S.
The third heat exchanger 310a is provided so as to bypass a second connection pipe 342a. A first end 311aa of the third heat exchanger 310a is connected to the four-way switching valve 370a side of the second connection pipe 342a. A second end 311ab of the third heat exchanger 310a is connected to the high-pressure refrigerant communication pipe 550 side of the second connection pipe 342a.

(2-1-2) Compressor 330a

The suction pipe 331 of the compressor 330a is connected to a third port 370ac (described later) of the four-way switching valve 370a.
The discharge pipe 332 of the compressor 330a is connected to a second port 370ab (described later) of the four-way switching valve 370a.

(2-1-3) Connection Pipe 340a

The connection pipe 340a includes a first connection pipe 341a, the second connection pipe 342a, a third connection pipe 343a, and a fourth connection pipe 344a.
The first connection pipe 341a has one end connected to a first port 370aa (described later) of the four-way switching valve 370a and the other end connected to the low-pressure refrigerant communication pipe 540.
The second connection pipe 342a has one end connected to a fourth port 370ad (described later) of the four-way switching valve 370a and the other end connected to the high-pressure refrigerant communication pipe 550.
The third connection pipe 343a has one end connected to a portion of the first connection pipe 341a between the four-way switching valve 370a and a first check valve 351a (described later), and the other end connected to a portion of the second connection pipe 342a between a second check valve 352a (described later) and the high-pressure refrigerant communication pipe 550.
The fourth connection pipe 344a has one end connected to a portion of the first connection pipe 341a between the low-pressure refrigerant communication pipe 540 and the first check valve 351a and the other end connected to a portion of the second connection pipe 342a between the second check valve 352a (described later) and the high-pressure refrigerant communication pipe 550.

(2-1-4) Check Valve 350a

The check valve 350a includes the first check valve 351a, the second check valve 352a, a third check valve 353a, and a fourth check valve 354a. As illustrated in FIG. 7, the first check valve 351a, the second check valve 352a, the third check valve 353a, and the fourth check valve 354a are arranged so as to constitute a bridge.
The first check valve 351a is provided in the first connection pipe 341a. The first check valve 351a allows the flow of the refrigerant from the low-pressure refrigerant communication pipe 540 to the four-way switching valve 370a, and restricts the flow of the refrigerant from the four-way switching valve 370a to the low-pressure refrigerant communication pipe 540.
The second check valve 352a is provided in the second connection pipe 342a. The second check valve 532a allows the flow of the refrigerant from the four-way switching valve 370a to the high-pressure refrigerant communication pipe 550, and restricts the flow of the refrigerant from the high-pressure refrigerant communication pipe 550 to the four-way switching valve 370a.
The third check valve 353a is provided in the third connection pipe 343a. The third check valve 353a allows the flow of the refrigerant from the first connection pipe 341a to the second connection pipe 342a, and restricts the flow of the refrigerant from the second connection pipe 342a to the first connection pipe 341a.
The fourth check valve 354a is provided in the fourth connection pipe 344a. The fourth check valve 354a allows the flow of the refrigerant from the first connection pipe 341a to the second connection pipe 342a, and restricts the flow of the refrigerant from the second connection pipe 342a to the first connection pipe 341a.

(2-1-5) Third Control Valve 360a

The third control valve 360a controls the flow of the refrigerant into the third heat exchanger 310a. The third control valve 360a is provided at the first end 311aa of the third heat exchanger 310a.
The third control valve 360a is controlled between the open state and the closed state by the control unit 700.

(2-1-6) Fourth Control Valve 390

The fourth control valve 390 controls the flow of the refrigerant in the second connection pipe 342a. The fourth control valve 390 is provided in the second connection pipe 342a so as to be positioned between the connection portion with the first end 311aa of the third heat exchanger 310a and the connection portion with the second end 310ab of the third heat exchanger 310a.
The fourth control valve 390 is controlled between the open state and the closed state by the control unit 700.
The fourth control valve 390 constitutes an example of a flow path adjustment mechanism together with the third control valve 360a.

(2-1-7) Four-Way Switching Valve 370a

The four-way switching valve 370a changes between the first state and the second state and switches the flow path of the refrigerant. The four-way switching valve 370a has the first port 370aa, the second port 370ab, the third port 370ac, and the fourth port 370ad. The first port 370aa is connected to the first connection pipe 341a. The second port 370ab is connected to the discharge pipe 332 of the compressor 330. The third port 370ac is connected to the suction pipe 331a of the compressor 330. The third port 370ac is connected to the first connection pipe 342b.
In the first state, the four-way switching valve 370a allows communication between the first port 370aa and the third port 370ac, and allows communication between the second port 370ab and the fourth port 370ad (see solid lines of the four-way switching valve 370a in FIG. 8A). In the second state, the four-way switching valve 370a allows communication between the first port 370aa and the second port 370ab, and allows communication between the third port 370ac and the fourth port 370ad (see dotted lines of the four-way switching valve 370a in FIG. 8A). The four-way switching valve 370a is controlled by a control unit 700a.

(2-2) Flow Path Switching Unit 600a

The flow path switching unit 600a switches the flow path of the refrigerant flowing through the refrigerant circuit 500a. The flow path switching unit 600a has a first liquid refrigerant pipe 610a, a first gas refrigerant pipe 620a, a first control valve 630a, a second liquid refrigerant pipe 640a, a second gas refrigerant pipe 650a, a second control valve 660a, a gas-liquid separator 670, and a third flow rate adjustment valve 680.
The first liquid refrigerant pipe 610a, the first gas refrigerant pipe 620a, the first control valve 630a, the second liquid refrigerant pipe 640a, the second gas refrigerant pipe 650a, the second control valve 660a, and the gas-liquid separator 670 are housed in a housing (not shown).

(2-2-1) First Liquid Refrigerant Pipe 610a

The first liquid refrigerant pipe 610a connects a liquid refrigerant outflow port 670c (described later) of the gas-liquid separator 670 to the air supply unit 100. The first liquid refrigerant pipe 610a has one end connected to the liquid refrigerant outflow port 670c and the other end connected to the first end 110a of the first heat exchanger 110.

(2-2-2) First Gas Refrigerant Pipe 620a

The first gas refrigerant pipe 620a connects the low-pressure refrigerant communication pipe 540 and a gas refrigerant outflow port 670b (described later) of the gas-liquid separator 670 to the air supply unit 100. The first gas refrigerant pipe 620a includes a first high and low-pressure gas refrigerant pipe 621a, a first low-pressure gas refrigerant pipe 622a, and a first junction gas refrigerant pipe 623a.
The first high and low-pressure gas refrigerant pipe 621a has one end connected to the gas refrigerant outflow port 670b and the other end connected to the first junction gas refrigerant pipe 623a.
The first low-pressure gas refrigerant pipe 622a has one end connected to the low-pressure refrigerant communication pipe 540 and the other end connected to the first junction gas refrigerant pipe 623a.
The first junction gas refrigerant pipe 623a has one end connected to the first high and low-pressure gas refrigerant pipe 621a and the first low-pressure gas refrigerant pipe 622a and the other end connected to the second end 110b of the first heat exchanger 110.

(2-2-3) First Control Valve 630a

The first control valve 630a controls the flow of the refrigerant in the first liquid refrigerant pipe 610a or the first gas refrigerant pipe 620a. The first control valve 630a includes a first high-pressure gas refrigerant control valve 631a and a first low-pressure gas refrigerant control valve 632a.
The first high-pressure gas refrigerant control valve 631a is provided in the first high and low-pressure gas refrigerant pipe 621a and controls the refrigerant flowing through the first high and low-pressure gas refrigerant pipe 621a.
The first low-pressure gas refrigerant control valve 632a is provided in the first low-pressure gas refrigerant pipe 622a and controls the refrigerant flowing through the first low-pressure gas refrigerant pipe 622a.
The first high-pressure gas refrigerant control valve 631 and the first low-pressure gas refrigerant control valve 632a are controlled between the open state and the closed state by the control unit 700a.

(2-2-4) Second Liquid Refrigerant Pipe 640a

The second liquid refrigerant pipe 640a connects the liquid refrigerant outflow port 670c of the gas-liquid separator 670 to the exhaust unit 200. The second liquid refrigerant pipe 640 has one end connected to the liquid refrigerant outflow port 670c and the other end connected to the first end 210a of the second heat exchanger 210.

(2-2-5) Second Gas Refrigerant Pipe 650a

The second gas refrigerant pipe 650a connects the low-pressure refrigerant communication pipe 540 and the gas refrigerant outflow port 670b of the gas-liquid separator 670 to the exhaust unit 200. The second gas refrigerant pipe 650a includes a second high and low-pressure gas refrigerant pipe 651a, a second low-pressure gas refrigerant pipe 652a, and a second junction gas refrigerant pipe 653a.
The second high and low-pressure gas refrigerant pipe 651a has one end connected to the gas refrigerant outflow port 670b and the other end connected to the second junction gas refrigerant pipe 653a.
The second low-pressure gas refrigerant pipe 652a has one end connected to the low-pressure refrigerant communication pipe 540 and the other end connected to the second junction gas refrigerant pipe 653a.
The second junction gas refrigerant pipe 653a has one end connected to the second high and low-pressure gas refrigerant pipe 651a and the second low-pressure gas refrigerant pipe 652a and the other end connected to the second end 210b of the second heat exchanger 210.

(2-2-6) Second Control Valve 660a

The second control valve 660a controls the flow of the refrigerant in the second liquid refrigerant pipe 640a or the second gas refrigerant pipe 650. The second control valve 660a includes a second high-pressure gas refrigerant control valve 661a, a second low-pressure gas refrigerant control valve 662a, and a second liquid refrigerant control valve 663a.
The second high-pressure gas refrigerant control valve 661a is provided in the second high and low-pressure gas refrigerant pipe 651a and controls the refrigerant flowing through the second high and low-pressure gas refrigerant pipe 651a.
The second low-pressure gas refrigerant control valve 662a is provided in the second low-pressure gas refrigerant pipe 652a and controls the refrigerant flowing through the second low-pressure gas refrigerant pipe 652a.
The second liquid refrigerant control valve 663a is provided in the second liquid refrigerant pipe 640a and controls the refrigerant flowing through the second liquid refrigerant pipe 640a.
The second high-pressure gas refrigerant control valve 661a, the second low-pressure gas refrigerant control valve 662a, and the second liquid refrigerant control valve 663a are controlled between the open state and the closed state by the control unit 700.

(2-2-7) Gas-Liquid Separator 670

The gas-liquid separator 670 separates the refrigerant flowing in from the high-pressure refrigerant communication pipe 550 into liquid refrigerant and gas refrigerant. The gas-liquid separator 670 has a refrigerant inflow port 670a, the gas refrigerant outflow port 670b, and the liquid refrigerant outflow port 670c.
The refrigerant inflow port 670a is connected to the high-pressure refrigerant communication pipe 550. The first high and low-pressure gas refrigerant pipe 621a is connected to the gas refrigerant outflow port 670b. The first liquid refrigerant pipe 610a is connected to the liquid refrigerant outflow port 670c.

(2-2-8) Third Flow Rate Adjustment Valve 680

The third flow rate adjustment valve 680 adjusts the flow rate of the refrigerant between the first liquid refrigerant pipe 610 and the gas-liquid separator 670. The third flow rate adjustment valve 680 is provided in the refrigerant pipe that connects the first liquid refrigerant pipe 610 to the gas-liquid separator 670.
The opening degree of the third flow rate adjustment valve 680 is controlled by the control unit 700a.

(2-3) Control Unit 700a

The control unit 700a is electrically connected to the first fan 120, the first flow rate adjustment valve 130, the sensor 140, the second fan 220, the second flow rate adjustment valve 230, the sensor 240, the third fan 320, the compressor 330a, the third control valve 360a, the fourth control valve 390, the four-way switching valve 370a, the sensor 380, the first control valve 630a (a first high-pressure gas refrigerant control valve 631a and a first low-pressure gas refrigerant control valve 632a), the second control valve 660a (a second high-pressure gas refrigerant control valve 661a and a second low-pressure gas refrigerant control valve 662a), and the third flow rate adjustment valve 680 so as to be capable of transmitting and receiving control signals and the like.
FIG. 9 is a block diagram schematically illustrating the control unit 700a and each portion connected to the control unit 700a.

(3) Operation of Ventilator 1a

(3-1) Temperature Adjustment Operation

FIGS. 10A and 10B are refrigerant circuit diagrams before the third heat exchanger functional state. FIG. 11 is a refrigerant circuit diagram during the third heat exchanger functional state. In FIGS. 10A, 10B, and 11, the direction in which the refrigerant flows is indicated by arrows. FIG. 10B illustrates, as an example, the ventilator 1 in which the pair 400a and the pair 400c perform the heating operation and the pair 400b performs the cooling operation.
Note that the flow of the refrigerant in the air supply unit 100, the exhaust unit 200, and the flow path switching unit 600a in the third heat exchanger functional state is similar to that in FIG. 10B, and thus description thereof is omitted.

(3-1-1) Compressor Unit 300a

When the temperature adjustment operation is started, the control unit 700a starts the compressor 330a, brings the third control valve 360a into the closed state, brings the fourth control valve 390a into the open state, and brings the four-way switching valve 370a into the first state. At this time, the control unit 700 does not start the third fan 320.
As a result, the compressor 330a sucks in the refrigerant in the low-pressure refrigerant communication pipe 540 from the suction pipe 331a via the first check valve 351a, the first port 370aa of the four-way switching valve 370a, and the third port 370ac of the four-way switching valve 370a, and discharges the refrigerant as high-pressure refrigerant from the discharge pipe 332a. The refrigerant compressed to a high pressure by the compressor 330a passes through the discharge pipe 332a, the second port 370ab of the four-way switching valve 370a, the fourth port 370ad of the four-way switching valve 370a, the fourth control valve 390, and the second check valve 352b in this order, and flows into the high-pressure refrigerant communication pipe 550. At this time, since the third control valve 360a is in the closed state, the flow of the refrigerant into the third heat exchanger 310 is restricted.
The control unit 700a controls the rotational speed of the compressor 330a so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperature, and the like.

(3-1-2) Flow Path Switching Unit 600a, and Pair 400 of Air Supply Unit 100 and Exhaust Unit 200 That Perform Cooling Operation

For the pair 400 (pair 400b in FIG. 10B) determined to execute the cooling operation, the control unit 700a closes the corresponding first high-pressure gas refrigerant control valve 631a, opens the first low-pressure gas refrigerant control valve 632a, opens the second high-pressure gas refrigerant control valve 661a, and closes the second low-pressure gas refrigerant control valve 662a. At the same time, the control unit 700a controls the rotational speed of the first fan 120 and the second fan 220 and adjusts the opening degrees of the first flow rate adjustment valve 130, the second flow rate adjustment valve 230, and the third flow rate adjustment valve 680 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperatures, and the like.
As a result, the refrigerant flowing into the gas-liquid separator 670 from the high-pressure refrigerant communication pipe 550 passes through the gas refrigerant outflow port 670b, the second high and low-pressure gas refrigerant pipe 651a, the second junction gas refrigerant pipe 653a, the second heat exchanger 210, and the second liquid refrigerant pipe 640a in this order. At this time, the flow rate of the refrigerant passing through the second liquid refrigerant pipe 640a is adjusted by the second flow rate adjustment valve 230.
The refrigerant flowing out of the second liquid refrigerant pipe 640a flows into the low-pressure refrigerant communication pipe 540 through the first liquid refrigerant pipe 610a, the first heat exchanger 110, the first junction gas refrigerant pipe 623a, and the first low-pressure gas refrigerant pipe 622a in this order together with the refrigerant flowing out of the liquid refrigerant outflow port 670c of the gas-liquid separator 670. At this time, the flow rate of the refrigerant passing through the first liquid refrigerant pipe 610a is adjusted by the first flow rate adjustment valve 130. The flow rate of the liquid refrigerant flowing out of the liquid refrigerant outflow port 670c of the gas-liquid separator 670 is also adjusted by the third flow rate adjustment valve 680.
With the refrigerant flowing in this manner, the first heat exchanger 110 functions as an evaporator for the refrigerant, and the second heat exchanger 210 functions as a condenser for the refrigerant. As a result, the air supply unit 100 cools the supply air SA blown by the first fan 120 in the first heat exchanger 110 and then discharges the cooled air into the target space S. In addition, the exhaust unit 200 heats the return air RA blown by the second fan 220 in the second heat exchanger 210 and then discharges the heated air to the outside of the target space S as the exhaust air EA. The heating of the return air RA by the exhaust unit 200 corresponds to heat recovery from the return air RA.

(3-1-3) Flow Path Switching Unit 600a, and Pair 400 of Air Supply Unit 100 and Exhaust Unit 200 That Perform Heating Operation

For the pairs 400 (pair 400a and pair 400c in FIG. 10B) determined to execute the heating operation, the control unit 700a opens the corresponding first high-pressure gas refrigerant control valve 631a, closes the first low-pressure gas refrigerant control valve 632a, closes the second high-pressure gas refrigerant control valve 661a, and opens the second low-pressure gas refrigerant control valve 662a. At the same time, the control unit 700a controls the rotational speed of the first fan 120 and the second fan 220 and adjusts the opening degrees of the first flow rate adjustment valve 130, the second flow rate adjustment valve 230, and the third flow rate adjustment valve 680 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperatures, and the like.
As a result, the refrigerant flowing into the gas-liquid separator 670 from the high-pressure refrigerant communication pipe 550 passes through the gas refrigerant outflow port 670b, the first high and low-pressure gas refrigerant pipe 621a, the first junction gas refrigerant pipe 623a, the first heat exchanger 110, and the first liquid refrigerant pipe 610a in this order. At this time, the flow rate of the refrigerant passing through the first liquid refrigerant pipe 610a is adjusted by the first flow rate adjustment valve 130.
The refrigerant flowing out of the first liquid refrigerant pipe 610a flows into the low-pressure refrigerant communication pipe 540 through the second liquid refrigerant pipe 640a, the second heat exchanger 210, the second junction gas refrigerant pipe 653a, and the second low-pressure gas refrigerant pipe 652a in this order together with the refrigerant flowing out of the liquid refrigerant outflow port 670c of the gas-liquid separator 670. At this time, the flow rate of the refrigerant passing through the second liquid refrigerant pipe 640a is adjusted by the second flow rate adjustment valve 230. The flow rate of the liquid refrigerant flowing out of the liquid refrigerant outflow port 670c of the gas-liquid separator 670 is also adjusted by the third flow rate adjustment valve 680.
With the refrigerant flowing in this manner, the first heat exchanger 110 functions as a condenser for the refrigerant, and the second heat exchanger 210 functions as an evaporator for the refrigerant. As a result, the air supply unit 100 heats the supply air SA blown by the first fan 120 in the first heat exchanger 110 and then discharges the heated air into the target space S. In addition, the exhaust unit 200 cools the return air RA blown by the second fan 220 in the second heat exchanger 210 and then discharges the cooled air to the outside of the target space S as the exhaust air EA. The cooling of the return air RA by the exhaust unit 200 corresponds to heat recovery from the return air RA.

(3-1-4) Pair 400 of Air Supply Unit 100 and Exhaust Unit 200 That Do Not Perform Temperature Adjustment Operation

Although not shown, the control unit 700a closes all of the first high-pressure gas refrigerant control valve 631a, the first low-pressure gas refrigerant control valve 632a, the second high-pressure gas refrigerant control valve 661a, and the second low-pressure gas refrigerant control valve 662a for the pair 400 determined not to execute the temperature adjustment operation.
Thus, the refrigerant flowing into the gas-liquid separator 670 from the high-pressure refrigerant communication pipe 550 is restricted from flowing into the air supply unit 100 and the exhaust unit 200. As a result, the first heat exchanger 110 and the second heat exchanger 210 are restricted from functioning as heat exchangers.

(3-1-5) Compressor Unit 300 during Third Heat Exchanger Functional State

Upon determining to bring the refrigerant circuit 500a into the third heat exchanger functional state, the control unit 700a switches the third control valve 360a, which is in the closed state, to the open state, closes the fourth control valve 390a, which is in the open state, to the closed state, and starts controlling the rotational speed of the third fan 320.
When the third control valve 360a is open and the fourth control valve 390 is closed, the refrigerant flowing through the discharge pipe 332 passes through the first port 370aa of the four-way switching valve 370a, the fourth port 370ad of the four-way switching valve 370a, the third control valve 360a, the third heat exchanger 310a, and the second check valve 352a in this order, and flows into the high-pressure refrigerant communication pipe 550. At this time, since the fourth control valve 390 is in the closed state, the passage of the refrigerant through the fourth control valve 390 is restricted. At this time, the control unit 700 starts controlling the rotational speed of the third fan 320 so that appropriate operating conditions are achieved (for example, so that one or more of the values of the evaporation temperature, condensation temperature, degree of subcooling, degree of superheating, and the like become target values) on the basis of the measurement values of the sensors 140, 240, and 380, the set temperature, and the like.
With the refrigerant flowing in this manner, the third heat exchanger 310a functions as a condenser for the refrigerant. As a result, even if the heat load of the first heat exchanger 110 functioning as an evaporator increases due to fluctuations in the outside air OA and the return air RA, the third heat exchanger 310 compensates for the capacity of the second heat exchanger 210 functioning as a condenser. Therefore, the ventilator 1 is capable of stable temperature adjustment.

(4) Modifications

(4-1) Modification 2A

When the four-way switching valve 370a is in the second state, the control unit 700a may bring the refrigerant circuit 500a into the third heat exchanger functional state. FIG. 12 is a refrigerant circuit diagram during the third heat exchanger functional state when the four-way switching valve 370a is in the second state.
In this case, when the third control valve 360a is open and the fourth control valve 390 is closed, the compressor 330 sucks in the refrigerant in the low-pressure refrigerant communication pipe 540 from the suction pipe 331a via the fourth check valve 354a, the third heat exchanger 310a, the third control valve 360a, the fourth port 370ad of the four-way switching valve 370a, and the third port 370ac of the four-way switching valve 370a, and discharges the refrigerant from the discharge pipe 332 as high-pressure refrigerant. The refrigerant compressed to a high pressure by the compressor 330a passes through the discharge pipe 332a, the second port 370ab of the four-way switching valve 370a, the first port 370aa of the four-way switching valve 370a, and the third check valve 353a in this order, and flows into the high-pressure refrigerant communication pipe 550.
With the refrigerant flowing in this manner, the third heat exchanger 310a functions as an evaporator for the refrigerant. As a result, even if the heat load of the first heat exchanger 110 functioning as a condenser increases due to fluctuations in the outside air OA and the return air RA, the third heat exchanger 310 compensates for the capacity of the second heat exchanger 210 functioning as an evaporator. Therefore, the ventilator 1 is capable of stable temperature adjustment.

While the embodiments according to the present disclosure have been described above, it will be understood that various changes in forms and details can be made without departing from the spirit and scope of the present disclosure recited in the claims.

REFERENCE SIGNS LIST

1, 1a: ventilator
100: air supply unit (first unit)
110: first heat exchanger
120: first fan
200: exhaust unit (second unit)
210: second heat exchanger
220: second fan
310, 310a: third heat exchanger
320: third fan
330, 330a: compressor
360, 360a: third control valve (flow path adjustment mechanism)
390: fourth control valve (flow path adjustment mechanism)
500, 500a: refrigerant circuit
700, 700a: control unit
OA: outside air
S: target space

CITATION LIST

PATENT LITERATURE

Patent Literature 1: JP 2023-051676 A

Claims

A ventilator (1, 1a) that ventilates air in a target space (S), the ventilator comprising:
a refrigerant circuit (500) that is configured by a compressor (330, 330a), a first heat exchanger (110), and a second heat exchanger (210) being connected, and is filled with a refrigerant;

a first fan (120) that discharges outside air (OA) into the target space (S) through the first heat exchanger (110), the outside air (OA) being air outside the target space (S); and

a second fan (220) that discharges air in the target space (S) to an outside of the target space (S) through the second heat exchanger (210),

wherein the refrigerant circuit (500)
is further connected to a third heat exchanger (310, 310a) that performs heat exchange between the refrigerant and a heat medium other than the refrigerant.
The ventilator (1, 1a) according to claim 1, further comprising a flow path adjustment mechanism (360, 360a, 390) that adjusts a flow path of the refrigerant flowing through the refrigerant circuit (500) between a first state in which the refrigerant is restricted from flowing into the third heat exchanger (310, 310a) and a second state in which the refrigerant is permitted to flow into the third heat exchanger (310, 310a).
The ventilator (1, 1a) according to claim 2, further comprising a control unit (700, 700a) that controls the flow path adjustment mechanism,
wherein the control unit (700, 700a)
determines whether the refrigerant in the refrigerant circuit is in a first refrigerant state on a basis of a pressure (Ps) or temperature (Te) of the refrigerant in the refrigerant circuit (500),

sets the flow path adjustment mechanism to the second state upon determining that the refrigerant in the refrigerant circuit is in the first refrigerant state, and

sets the flow path adjustment mechanism to the first state upon determining that the refrigerant in the refrigerant circuit is not in the first refrigerant state.
The ventilator (1, 1a) according to claim 3, further comprising a third fan (320) that blows air to the third heat exchanger (310, 310a),
wherein the control unit (700, 700a)
determines whether the refrigerant in the refrigerant circuit is in the first refrigerant state on the basis of the pressure (Ps) or temperature (Te) of the refrigerant in the refrigerant circuit (500),

operates the third fan upon determining that the refrigerant in the refrigerant circuit is in the first refrigerant state, and

stops the third fan upon determining that the refrigerant in the refrigerant circuit is not in the first refrigerant state.
The ventilator (1, 1a) according to any one of claims 1 to 4, further comprising a third fan (320) that blows air to the third heat exchanger (310, 310a),
wherein the third heat exchanger (310, 310a), the third fan (320), and the compressor (330) are housed in a single housing.
The ventilator (1, 1a) according to any one of claims 1 to 5, wherein the third heat exchanger (310, 310a) is installed outside the target space (S).
The ventilator (1, 1a) according to any one of claims 1 to 5, further comprising:
a plurality of first units (100) each having the first heat exchanger (110) and the first fan (120); and

a plurality of second units (200) each having the second heat exchanger (210) and the second fan (220).
The ventilator (1, 1a) according to any one of claims 1 to 7, wherein the heat medium is the outside air (OA).
The ventilator (1, 1a) according to any one of claims 1 to 8, wherein
the third heat exchanger (310, 310a)
functions as an evaporator when the second heat exchanger (210) functions as an evaporator, and

functions as a condenser when the second heat exchanger (210) functions as a condenser.