Refrigeration cycle device, and method for controlling the electric expansion valve of the refrigeration cycle device.

Abstract

To improve the reliability of the control that closes the electric expansion valve. [Solution] The system includes an indoor expansion valve (36a, 36b), a refrigerant circuit (90) through which the refrigerant circulates, and a controller (70) that controls the opening degree of the indoor expansion valve (36a, 36b). The controller (70) performs a first control to increase the valve opening degree of the indoor expansion valve (36a, 36b) when a refrigerant leak is detected by a refrigerant sensor (38a, 38b) and the state of being less than a predetermined minute opening degree continues for a predetermined period of time or longer. After that, the controller (70) closes the indoor expansion valve (36a, 36b) completely.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle apparatus and a control method for an electric expansion valve of the refrigeration cycle apparatus.

Background Art

[0002] Conventionally, in a refrigeration cycle apparatus including a refrigerant circuit having an electric expansion valve, the passage state of refrigerant through the electric expansion valve is adjusted by controlling the valve opening degree of the electric expansion valve.

[0003] For example, according to Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2016-035356), it has been proposed to perform an operation of recovering the refrigerant in the refrigerant circuit to an outdoor heat exchanger by closing an expansion mechanism and operating a compressor.

Disclosure of the Invention

Problem to be Solved by the Invention

[0004] However, even when control for closing an electric expansion valve such as the aforementioned expansion mechanism is started, the electric expansion valve may remain incompletely closed, for example, due to foreign matter such as dust present in the refrigerant circuit entering between the valve seat and the valve body.

[0005] For this reason, it is desired to improve the reliability of control for closing the electric expansion valve.

Means for Solving the Problem

[0006] A refrigeration cycle apparatus according to a first aspect includes a refrigerant circuit and a control unit. The refrigerant circuit has an electric expansion valve. Refrigerant circulates through the refrigerant circuit. The control unit controls the opening degree of the electric expansion valve. When a predetermined condition including a predetermined fully-closing condition is satisfied, the control unit performs first control for increasing the valve opening degree of the electric expansion valve, and then performs second control for fully closing the electric expansion valve.

[0007] Here, "increasing the valve opening of the electric expansion valve" means that the valve opening is greater than the valve opening of the electric expansion valve at the time the first control is started.

[0008] According to this refrigeration cycle system, a first control is performed to increase the valve opening of the electric expansion valve before attempting to fully close it. This allows any foreign objects, such as debris, present around the electric expansion valve to be moved to a location away from it. As a result, when the second control is performed to fully close the electric expansion valve, it is more likely to be fully closed, thus increasing the reliability of the electric expansion valve control.

[0009] The refrigeration cycle device relating to the second aspect is the refrigeration cycle device relating to the first aspect, wherein the control unit, in the first control, maintains a state in which the valve opening of the electric expansion valve is at or above a first predetermined opening until the first predetermined period condition is met. The second control is performed immediately after the first control is performed.

[0010] Here, the "first predetermined period condition" may be the elapsed time of a predetermined period, such as 0.5 seconds to 1 second, or it may be the elapsed time required for the electric expansion valve to reach a predetermined opening.

[0011] With this refrigeration cycle system, even if foreign objects such as debris are present around the electric expansion valve, it is easy to move the foreign objects away from the electric expansion valve before the second control is performed.

[0012] A refrigeration cycle device relating to the third perspective is a refrigeration cycle device relating to the first or second perspective, and the predetermined conditions include a pre-state condition. The pre-state condition is that the valve opening of the electric expansion valve is less than the second predetermined opening, and this state continues for a period of time or longer that satisfies the second predetermined period condition.

[0013] Here, "a state where the opening is less than the second predetermined opening" may be, for example, a valve opening of half or less of the valve opening when the electric expansion valve is fully open, or a valve opening of one-third or less, or a valve opening of one-fifth or less.

[0014] Furthermore, the "second predetermined period condition" may be, for example, the elapsed of a predetermined time, or, if the refrigerant circuit has a compressor, the cumulative rotational speed of the compressor.

[0015] According to this refrigeration cycle device, if the valve opening of the electric expansion valve remains below the second predetermined opening for a period of time or longer that satisfies the second predetermined period condition, foreign matter such as dirt is more likely to accumulate around the electric expansion valve. However, even in such a situation where foreign matter such as dirt is likely to accumulate around the electric expansion valve, the second control can more reliably bring the electric expansion valve to a fully closed state.

[0016] The refrigeration cycle device relating to the fourth aspect is the refrigeration cycle device relating to the third aspect, wherein the control unit controls the valve opening of the electric expansion valve to be less than a second predetermined opening when the heat load to be processed is in a predetermined low load state.

[0017] This refrigeration cycle system controls the valve opening of the electric expansion valve to be less than a second predetermined opening when under a predetermined low load condition, thereby making it possible to limit the amount of refrigerant circulating in the refrigerant circuit to an amount corresponding to the heat load being processed.

[0018] The refrigeration cycle device relating to the fifth aspect is a refrigeration cycle device relating to the third or fourth aspect, wherein the refrigerant circuit includes a compressor, an outdoor heat exchanger, an indoor heat exchanger, a first flow path extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with an electric expansion valve, and a second flow path extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with a compressor. The refrigerant circuit is capable of performing heating operation by making the indoor heat exchanger function as a refrigerant heat radiator. The control unit controls the valve opening of the electric expansion valve to be less than a second predetermined opening and not in a fully closed state when the conditions relating to the set temperature corresponding to the indoor heat exchanger are met.

[0019] This refrigeration cycle system prevents liquid refrigerant from accumulating in the indoor heat exchanger during heating operation, provided that the conditions related to the set temperature corresponding to the indoor heat exchanger are met.

[0020] The refrigeration cycle device relating to the sixth aspect is a refrigeration cycle device relating to the third or fourth aspect, wherein the refrigerant circuit includes a compressor, an outdoor heat exchanger, an indoor heat exchanger, a first flow path extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with an electric expansion valve, and a second flow path extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with a compressor. The refrigerant circuit is capable of performing cooling operation by making the indoor heat exchanger function as a refrigerant evaporator. The control unit satisfies a predetermined totally closed condition when the conditions relating to the set temperature corresponding to the indoor heat exchanger are met.

[0021] According to this refrigeration cycle system, during cooling operation, when the conditions related to the set temperature corresponding to the indoor heat exchanger are met, a predetermined fully closed condition is met, thereby suppressing the situation in which the indoor heat exchanger continues to absorb heat from the surroundings.

[0022] A refrigeration cycle device relating to the seventh aspect is a refrigeration cycle device relating to the third or fourth aspect, wherein the refrigerant circuit includes a compressor, an outdoor heat exchanger, a first indoor heat exchanger, a second indoor heat exchanger, a first electric expansion valve which is an electric expansion valve, a second electric expansion valve which is an electric expansion valve, a first main flow path extending from the outdoor heat exchanger to a first branch section, a first branch flow path extending from the first branch section to the first indoor heat exchanger and equipped with a first electric expansion valve, a second branch flow path extending from the first branch section to the second indoor heat exchanger and equipped with a second electric expansion valve, a second main flow path extending from the outdoor heat exchanger to a second branch section and equipped with a compressor, a third branch flow path extending from the second branch section to the first indoor heat exchanger, and a fourth branch flow path extending from the second branch section to the second indoor heat exchanger.

[0023] This refrigeration cycle system makes it possible to individually control the amount of refrigerant supplied to the first indoor heat exchanger and the amount of refrigerant supplied to the second indoor heat exchanger.

[0024] A refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to the seventh aspect, wherein the refrigerant circuit is capable of performing a heating operation in which the first indoor heat exchanger and the second indoor heat exchanger function as refrigerant radiators. The control unit controls the opening degree of the first electric expansion valve to be less than a second predetermined opening degree and not in a fully closed state when a condition relating to a set temperature corresponding to the first indoor heat exchanger is satisfied. The control unit controls the opening degree of the second electric expansion valve to be less than the second predetermined opening degree and not in a fully closed state when a condition relating to a set temperature corresponding to the second indoor heat exchanger is satisfied.

[0025] According to this refrigeration cycle apparatus, accumulation of liquid refrigerant in the first indoor heat exchanger is suppressed when the condition relating to the set temperature corresponding to the first indoor heat exchanger is satisfied during heating operation, and accumulation of liquid refrigerant in the second indoor heat exchanger is suppressed when the condition relating to the set temperature corresponding to the second indoor heat exchanger is satisfied during heating operation.

[0026] A refrigeration cycle apparatus according to a ninth aspect is the refrigeration cycle apparatus according to the seventh aspect or the eighth aspect, wherein the refrigerant circuit is capable of performing a cooling operation in which the first indoor heat exchanger and the second indoor heat exchanger function as refrigerant evaporators. The first electric expansion valve satisfies a predetermined fully-closing condition when a condition relating to a set temperature corresponding to the first indoor heat exchanger is satisfied. The second electric expansion valve satisfies the predetermined fully-closing condition when a condition relating to a set temperature corresponding to the second indoor heat exchanger is satisfied.

[0027] According to this refrigeration cycle apparatus, when the condition relating to the set temperature corresponding to the first indoor heat exchanger is satisfied during cooling operation, the predetermined fully-closing condition is satisfied, thereby suppressing a situation where the first indoor heat exchanger continues absorbing heat from the surroundings; and when the condition relating to the set temperature corresponding to the second indoor heat exchanger is satisfied during cooling operation, the predetermined fully-closing condition is satisfied, thereby suppressing a situation where the second indoor heat exchanger continues absorbing heat from the surroundings.

[0028] A refrigeration cycle apparatus according to a 10th aspect is the refrigeration cycle apparatus according to any one of the 1st to 9th aspects, and further includes a leakage detector. The leakage detector detects refrigerant that has leaked from a refrigerant circuit. The predetermined fully-closing condition includes that refrigerant leakage is detected by the leakage detector.

[0029] According to this refrigeration cycle apparatus, it is possible to improve the reliability of control for fully closing the electric expansion valve when refrigerant leaks from the refrigerant circuit.

[0030] A refrigeration cycle apparatus according to an 11th aspect is the refrigeration cycle apparatus according to any one of the 3rd to 9th aspects, wherein when the predetermined fully-closing condition is satisfied without the pre-condition being satisfied, a control unit executes second control without executing first control.

[0031] According to this refrigeration cycle apparatus, in a situation where there is a low possibility that foreign matter such as dust is present around the electric expansion valve that does not satisfy the pre-condition, starting the second control by omitting the first control that increases the opening degree of the electric expansion valve allows the electric expansion valve to be quickly brought into the fully closed state.

[0032] A refrigeration cycle apparatus according to a 12th aspect is the refrigeration cycle apparatus according to any one of the 1st to 4th aspects, wherein the refrigerant circuit includes a compressor, an outdoor heat exchanger, an indoor heat exchanger, a first flow path that extends from the outdoor heat exchanger to the indoor heat exchanger and is provided with the electric expansion valve, and a second flow path that extends from the outdoor heat exchanger to the indoor heat exchanger and is provided with the compressor. The control unit is capable of pump-down operation control that causes the outdoor heat exchanger to function as a refrigerant radiator while bringing the electric expansion valve into a fully closed state. The predetermined condition is satisfied when the pump-down operation control is started.

[0033] According to this refrigeration cycle apparatus, leakage flow of refrigerant through the electric expansion valve during pump-down operation is suppressed.

[0034] The refrigeration cycle device relating to the 13th aspect is a refrigeration cycle device relating to either the 1st aspect or the 12th aspect, wherein the control unit, in the first control, increases the valve opening of the electric expansion valve to half open or more.

[0035] This refrigeration cycle system makes it possible to more reliably move foreign objects, such as debris, away from the electric expansion valve, even if they are present around it.

[0036] A refrigeration cycle device relating to the 14th aspect is a refrigeration cycle device relating to any of the 13th aspects of the 1st aspect, wherein the refrigerant is a refrigerant having at least one of a predetermined toxicity and a predetermined flammability.

[0037] Examples of such refrigerants include carbon dioxide refrigerant, R32, and propane.

[0038] This refrigeration cycle system makes it possible to improve the reliability of the control of the electric expansion valve when a refrigerant with a predetermined toxicity or flammability is used.

[0039] The refrigeration cycle device relating to the 15th perspective is a refrigeration cycle device relating to either the 1st perspective or the 14th perspective, and the refrigerant is carbon dioxide refrigerant.

[0040] This refrigeration cycle system makes it possible to improve the reliability of the control of the electric expansion valve when a toxic refrigerant is used.

[0041] The control method for an electric expansion valve of a refrigeration cycle device relating to the 16th aspect is a control method for an electric expansion valve of a refrigeration cycle device, wherein the refrigeration cycle device comprises a refrigerant circuit through which a refrigerant circulates and which has an electric expansion valve, and a control unit that controls the opening degree of the electric expansion valve. When predetermined conditions, including a predetermined fully closed condition, are met, the control unit performs a first control to increase the valve opening degree of the electric expansion valve, and then performs a second control to fully close the electric expansion valve.

[0042] Here, "increasing the valve opening of the electric expansion valve" means that the valve opening is greater than the valve opening of the electric expansion valve at the time the first control is started.

[0043] According to this control method for the electric expansion valve of the refrigeration cycle system, a first control is performed to increase the valve opening of the electric expansion valve before attempting to fully close it. This makes it possible to move any foreign objects, such as debris, that are present around the electric expansion valve to a location away from it. As a result, when the second control is performed to fully close the electric expansion valve, it is more likely to fully close, thus increasing the reliability of the electric expansion valve control. [Brief explanation of the drawing]

[0044] [Figure 1] This is a schematic diagram of the refrigeration cycle device according to an embodiment. [Figure 2] This is a control block diagram of the refrigeration cycle system. [Figure 3] This is a schematic cross-sectional diagram of the indoor expansion valve. [Figure 4] This is a control flowchart for refrigerant leakage prevention processing. [Figure 5] This is a control flowchart related to turning off the cooling thermostat in another embodiment A. [Modes for carrying out the invention]

[0045] An embodiment of the refrigeration cycle device will be described with reference to the drawings.

[0046] (1) Overall structure The refrigeration cycle device 100 of this embodiment will be described with reference to the schematic configuration diagram in Figure 1.

[0047] The refrigeration cycle system 100 is an air conditioning system that provides air conditioning for multiple air-conditioned spaces within a building. The refrigeration cycle system 100 mainly consists of an outdoor unit 10, multiple indoor units 30, and a controller 70 (see Figure 1). Note that the number of indoor units 30 shown in Figure 1 does not limit the total number of indoor units 30 in the refrigeration cycle system 100. Furthermore, unlike this embodiment, the refrigeration cycle system 100 may have only one indoor unit 30 and provide air conditioning for a single air-conditioned space.

[0048] As shown in Figure 1, the outdoor unit 10 and the indoor unit 30 are connected by a liquid-side connecting pipe 2, a first liquid-side branch pipe 2a and a second liquid-side branch pipe 2b that branch off at the first branch point X, which is the indoor unit end of the liquid-side connecting pipe 2, and a gas-side connecting pipe 4, and a first gas-side branch pipe 4a and a second gas-side branch pipe 4b that branch off at the second branch point Y, which is the indoor unit end of the gas-side connecting pipe 4. By connecting the outdoor unit 10 and the multiple indoor units 30 with these pipes, a refrigerant circuit 90 is formed, which includes a compressor 12, an outdoor heat exchanger 16, an outdoor expansion valve 18, an indoor expansion valve 36, an indoor heat exchanger 32, etc., which will be described later. The liquid-side connecting pipe 2 is a liquid connecting pipe through which refrigerant flows from the outdoor unit 10 to the indoor unit 30 during cooling operation, and from the indoor unit 30 to the outdoor unit 10 during heating operation. The gas-side connecting pipe 4 is a gas connecting pipe through which refrigerant flows from the indoor unit 30 to the outdoor unit 10 during cooling operation, and from the outdoor unit 10 to the indoor unit 30 during heating operation. The controller 70 controls the operation of each part of the refrigeration cycle device 100.

[0049] The refrigerant used in the refrigerant circuit 90 is not particularly limited, but in this embodiment, for example, the case in which carbon dioxide is used as the refrigerant will be described as an example.

[0050] (2) Detailed configuration (2-1) Indoor Unit The indoor unit 30 is installed in the air-conditioned space that is the target of air conditioning. The indoor unit 30 is, for example, a ceiling-mounted type, a ceiling-suspended type, a wall-mounted type, or a floor-standing type unit. In this embodiment, the case in which a first indoor unit 30a and a second indoor unit 30b, which have similar configurations to each other, are provided as the indoor unit 30 will be described as an example. The first indoor unit 30a and the second indoor unit 30b are connected in parallel to each other in the refrigerant circuit 90. The components of the first indoor unit 30a will be described with the subscript "a", and the components of the second indoor unit 30b will be described with the subscript "b". In the following, the subscripts "a" and "b" may be omitted, and either or both of the first indoor unit 30a and the second indoor unit 30b and their components may be referred to.

[0051] The first indoor unit 30a mainly comprises a first indoor heat exchanger 32a, a first indoor fan 34a, a first indoor expansion valve 36a, a first indoor control unit 72a, a first gas side valve 37a, a first indoor heat exchanger temperature sensor 35a, a first indoor temperature sensor 33a, a first refrigerant sensor 38a, and a first casing 31a housing these components.

[0052] In the first indoor heat exchanger 32a, heat exchange takes place between the refrigerant flowing inside the first indoor heat exchanger 32a and the air in the air-conditioned space. The first indoor heat exchanger 32a is, for example, a fin-and-tube type heat exchanger having a plurality of heat transfer fins and a plurality of heat transfer tubes.

[0053] The first indoor fan 34a supplies air taken in from the air-conditioned space to the first indoor heat exchanger 32a. The first indoor fan 34a is a centrifugal fan, such as a turbo fan or a sirocco fan. The first indoor fan 34a is driven by a motor (not shown).

[0054] The first indoor expansion valve 36a is installed in the first liquid-side branch pipe 2a, which connects the liquid-side connecting pipe 2 to the liquid-side end of the first indoor heat exchanger 32a, and is a mechanism for adjusting the pressure and flow rate of the refrigerant. The first indoor expansion valve 36a is an electrically operated expansion valve, such as an electronic expansion valve, with adjustable opening. The first indoor expansion valve 36a comprises a valve seat, a valve body, and a stepping motor that drives the valve body. By driving the stepping motor, the valve body moves relative to the valve seat, making the minimum flow path area between the valve body and the valve seat variable. The first indoor expansion valve 36a is also used as a shut-off valve to block the flow path, and is a valve with low leakage when closed. For example, the first indoor expansion valve 36a has a leakage of 300 cm³ when closed. 3 The valve has a pressure of / min (air, ΔP = 1.0 MPa) or less. Furthermore, the material of the valve seat and valve body of the first chamber expansion valve 36a is not particularly limited, but may be selected from SUS and brass, etc., and it is preferable that both the valve seat and valve body be made of SUS from the viewpoint that they have sufficient strength to be easily crushed even if foreign matter gets stuck between them.

[0055] In this embodiment, the first chamber expansion valve 36a may, more specifically as shown in Figure 3, be a motor-driven expansion valve comprising a valve body 41, a valve seat 42, and a drive mechanism (not shown). The valve body 41 is needle-shaped with a tapered tip, and its position is controlled to move axially by the drive mechanism. The valve seat 42 has an orifice hole 43 into which the tip of the valve body 41 is inserted. By controlling the position of the valve body 41 relative to the valve seat 42 in this way, the size of the flow path area in the first chamber expansion valve 36a is controlled.

[0056] The first gas-side valve 37a is installed in the first gas-side branch pipe 4a that connects the gas-side connecting pipe 4 to the gas-side end of the first indoor heat exchanger 32a, and has a variable valve opening mechanism. The first gas-side valve 37a in this embodiment is an electrically operated expansion valve such as an electronic expansion valve with adjustable opening. The first gas-side valve 37a comprises a valve seat, a valve body, and a stepping motor that drives the valve body. By driving the stepping motor, the valve body moves relative to the valve seat, making the minimum flow path area between the valve body and the valve seat variable. The first gas-side valve 37a is also used as a shut-off valve to block the flow path, and is a valve with low leakage when closed. For example, the first gas-side valve 37a has a leakage amount of 300 cm when closed. 3 This valve has a flow rate of less than / min (air, ΔP = 1.0 MPa).

[0057] The first indoor heat exchanger temperature sensor 35a detects the temperature of the refrigerant flowing at the liquid-side outlet of the first indoor heat exchanger 32a.

[0058] The first indoor temperature sensor 33a detects the temperature of the indoor air drawn in from the room before heat exchange occurs in the first indoor heat exchanger 32a.

[0059] The first refrigerant sensor 38a is a sensor that detects refrigerant leakage. The first refrigerant sensor 38a is installed, for example, near the first indoor heat exchanger 32a.

[0060] The first indoor control unit 72a has a control arithmetic unit and a memory device. The control arithmetic unit is a processor such as a CPU and a GPU. The memory device is a storage medium such as RAM, ROM, and flash memory. The control arithmetic unit reads a program stored in the memory device and performs predetermined calculation processing according to the program, and in cooperation with the outdoor control unit 74 of the outdoor unit 10, acts as a controller 70 to control the operation of various devices of the refrigeration cycle device 100. The functions of the controller 70 will be described later.

[0061] The second indoor unit 30b mainly comprises a second indoor heat exchanger 32b, a second indoor fan 34b, a second indoor expansion valve 36b, a second indoor control unit 72b, a second gas-side valve 37b, a second indoor heat exchanger temperature sensor 35b, a second indoor temperature sensor 33b, a second refrigerant sensor 38b, and a second casing 31b housing these components. Since the configuration of the second indoor unit 30b is the same as that of the first indoor unit 30a, a detailed explanation is omitted.

[0062] (2-2) Outdoor unit The outdoor unit 10 is installed on the rooftop or in the machine room of the building where the refrigeration cycle device 100 is installed. As shown in Figure 1, the outdoor unit 10 mainly includes a compressor 12, a flow path switching valve 14, an outdoor heat exchanger 16, an outdoor expansion valve 18, an accumulator 20, an outdoor fan 22, a liquid shut-off valve 24, a gas shut-off valve 26, a discharge pressure sensor 21, an intake pressure sensor 23, an intake temperature sensor 25, an outdoor heat exchanger temperature sensor 27, and an outdoor control unit 74. The outdoor unit 10 also includes an intake pipe 28a, a discharge pipe 28b, a first gas refrigerant pipe 28c, a second gas refrigerant pipe 28e, a liquid refrigerant pipe 28d, and a casing 11 that houses these.

[0063] The suction pipe 28a connects the flow path switching valve 14 to the suction side of the compressor 12. An accumulator 20 is provided in the suction pipe 28a. The discharge pipe 28b connects the discharge side of the compressor 12 to the flow path switching valve 14. The first gas refrigerant piping 28c connects the flow path switching valve 14 to the gas side end of the outdoor heat exchanger 16. The liquid refrigerant piping 28d connects the liquid side end of the outdoor heat exchanger 16 to the liquid side connecting pipe 2. An outdoor expansion valve 18 is provided in the liquid refrigerant piping 28d. A liquid shut-off valve 24 is provided at the connection between the liquid refrigerant piping 28d and the liquid side connecting pipe 2. The second gas refrigerant piping 28e connects the flow path switching valve 14 to the gas side connecting pipe 4. A gas shut-off valve 26 is provided at the connection between the second gas refrigerant piping 28e and the gas side connecting pipe 4. The liquid shut-off valve 24 and the gas shut-off valve 26 are valves that are opened and closed manually.

[0064] The compressor 12 draws in low-pressure refrigerant from the refrigeration cycle through the suction pipe 28a, compresses the refrigerant using a compression mechanism (not shown), and discharges the compressed high-pressure refrigerant from the refrigeration cycle through the discharge pipe 28b. The compressor 12 is, for example, a positive displacement compressor such as a rotary or scroll type. The compression mechanism of the compressor 12 is driven by a motor (not shown). The rotational speed of the motor of the compressor 12 can be controlled by an inverter.

[0065] The flow path switching valve 14 is a mechanism that switches the flow path of the refrigerant between a first state and a second state. In the first state, as shown by the solid line in the flow path switching valve 14 in Figure 1, the suction pipe 28a is connected to the second gas refrigerant piping 28e and the discharge pipe 28b is connected to the first gas refrigerant piping 28c. In the second state, as shown by the dashed line in the flow path switching valve 14 in Figure 1, the suction pipe 28a is connected to the first gas refrigerant piping 28c and the discharge pipe 28b is connected to the second gas refrigerant piping 28e. The flow path switching valve 14 is, for example, a four-way switching valve or a combination of multiple three-way valves.

[0066] During cooling operation, the flow path switching valve 14 sets the refrigerant flow path to the first state. At this time, the refrigerant discharged from the compressor 12 flows through the refrigerant circuit 90 in the order of outdoor heat exchanger 16, outdoor expansion valve 18, first indoor expansion valve 36a, first indoor heat exchanger 32a, and then in the order of second indoor expansion valve 36b, second indoor heat exchanger 32b, before returning to the compressor 12. In the first state, the outdoor heat exchanger 16 functions as a radiator or condenser, and the first indoor heat exchanger 32a and second indoor heat exchanger 32b function as evaporators.

[0067] During heating operation, the flow path switching valve 14 sets the refrigerant flow path to the second state. At this time, the refrigerant discharged from the compressor 12 flows through the refrigerant circuit 90 in the following order: first indoor heat exchanger 32a, first indoor expansion valve 36a, then second indoor heat exchanger 32b, second indoor expansion valve 36b, outdoor expansion valve 18, and outdoor heat exchanger 16, before returning to the compressor 12. In the second state, the outdoor heat exchanger 16 functions as an evaporator, and the first indoor heat exchanger 32a and second indoor heat exchanger 32b function as radiators or condensers.

[0068] The outdoor heat exchanger 16 performs heat exchange between the refrigerant flowing inside the outdoor heat exchanger 16 and the air surrounding the outdoor unit 10. The outdoor heat exchanger 16 is, for example, a fin-and-tube type heat exchanger having a plurality of heat transfer fins and a plurality of heat transfer tubes.

[0069] The outdoor expansion valve 18 is a mechanism for regulating the pressure and flow rate of the refrigerant flowing through the liquid refrigerant piping 28d. As shown in Figure 1, the outdoor expansion valve 18 is installed in the liquid refrigerant piping 28d. The outdoor expansion valve 18 is an electrically operated expansion valve, such as an electronic expansion valve, with adjustable opening.

[0070] The accumulator 20 is installed in the suction pipe 28a and is a container with a gas-liquid separation function that separates the incoming refrigerant into gaseous refrigerant and liquid refrigerant. The refrigerant flowing into the accumulator 20 is separated into gaseous refrigerant and liquid refrigerant, and the gaseous refrigerant that collects in the upper space flows into the compressor 12.

[0071] The outdoor fan 22 supplies air from around the outdoor unit 10 to the outdoor heat exchanger 16. The outdoor fan 22 is, for example, an axial fan such as a propeller fan. The outdoor fan 22 is driven by a motor (not shown).

[0072] The discharge pressure sensor 21 is installed between the compressor 12 and the flow path switching valve 14 and detects the pressure of the refrigerant discharged from the compressor 12.

[0073] The suction pressure sensor 23 is installed between the accumulator 20 and the compressor 12 and detects the pressure of the refrigerant being drawn into the compressor 12.

[0074] The intake temperature sensor 25 is installed between the accumulator 20 and the compressor 12 and detects the temperature of the refrigerant being drawn into the compressor 12.

[0075] The outdoor heat exchanger temperature sensor 27 detects the temperature of the refrigerant flowing at the liquid side outlet of the outdoor heat exchanger 16.

[0076] The outdoor control unit 74 has a control calculation device and a memory device. The control calculation device is a processor such as a CPU and a GPU. The memory device is a storage medium such as RAM, ROM, and flash memory. The control calculation device reads a program stored in the memory device and performs predetermined calculation processing according to the program, and in cooperation with the indoor control unit 72 of the indoor unit 30, acts as a controller 70 to control the operation of various devices of the refrigeration cycle device 100. The functions of the controller 70 will be described later.

[0077] (2-3) Controller The controller 70 consists of a first indoor control unit 72a, a second indoor control unit 72b, and an outdoor control unit 74. The controller 70 controls the operation of the entire refrigeration cycle system 100 by causing the control calculation devices of the first indoor control unit 72a, the second indoor control unit 72b, and the outdoor control unit 74 to execute programs stored in their respective memory devices.

[0078] Figure 2 is a control block diagram of the refrigeration cycle device 100 in this embodiment.

[0079] As shown in Figure 2, the controller 70 is electrically connected to the first gas side valve 37a, first indoor expansion valve 36a, first indoor fan 34a, first indoor heat exchange temperature sensor 35a, first indoor temperature sensor 33a, and first refrigerant sensor 38a of the first indoor unit 30a; to the second gas side valve 37b, second indoor expansion valve 36b, second indoor fan 34b, second indoor heat exchange temperature sensor 35b, second indoor temperature sensor 33b, and second refrigerant sensor 38b of the second indoor unit 30b; and to the compressor 12, flow path switching valve 14, outdoor expansion valve 18, discharge pressure sensor 21, suction pressure sensor 23, suction temperature sensor 25, outdoor heat exchange temperature sensor 27, and outdoor fan 22 of the outdoor unit 10. The controller 70 is also electrically connected to various sensors that measure the temperature and pressure of the refrigerant, the temperature of the air in the air-conditioned space, the outside air temperature, etc. The controller 70 controls the operation of various devices in the refrigeration cycle system 100 based on control signals received by the first indoor unit 30a and the second indoor unit 30b from an operating remote control (not shown), as well as measurement signals from various sensors.

[0080] The controller 70 primarily performs cooling and heating operations. Furthermore, the controller 70 is capable of performing the refrigerant leakage prevention treatment described later.

[0081] (2-3-1) Cooling operation When the controller 70 receives an instruction to start cooling operation, for example from the operating remote control via the indoor unit 30, it sets the flow path switching valve 14 to the first state and starts the operation of the compressor 12. In addition, based on the measurement results of sensors that measure the temperature and pressure of the refrigerant, which are provided in the refrigerant circuit 90, and the set temperature, the controller 70 appropriately controls the rotation speed of the compressor 12 motor and the opening degrees of the outdoor expansion valve 18, the first indoor expansion valve 36a, and the second indoor expansion valve 36b. During cooling operation, the first gas side valve 37a and the second gas side valve 37b are controlled to be fully open.

[0082] The flow of refrigerant in the refrigerant circuit 90 will be explained.

[0083] When the compressor 12 starts operating, the low-pressure gaseous refrigerant in the refrigeration cycle (hereinafter simply referred to as low-pressure) is drawn into the compressor 12 and compressed by the compressor's compression mechanism to become the high-pressure refrigerant in the refrigeration cycle (hereinafter simply referred to as high-pressure). The high-pressure refrigerant is sent to the outdoor heat exchanger 16 via the flow path switching valve 14, where it exchanges heat with the air surrounding the outdoor unit 10 supplied by the outdoor fan 22 and dissipates heat. The refrigerant that has dissipated heat in the outdoor heat exchanger 16 flows through the liquid refrigerant piping 28d and passes through the outdoor expansion valve 18. In this embodiment, for example, during cooling operation, the valve opening of the outdoor expansion valve 18 is controlled so that the degree of subcooling of the refrigerant flowing out of the outlet of the outdoor heat exchanger 16 satisfies predetermined conditions. Specifically, the degree of subcooling determined from the pressure-equivalent saturation temperature obtained from the discharge pressure sensor 21 and the refrigerant temperature detected by the outdoor heat exchanger temperature sensor 27 is controlled so that it satisfies predetermined conditions. The refrigerant that has passed through the outdoor expansion valve 18 and flowed through the liquid-side connecting pipe 2 is divided at the first branching point X into the first liquid-side branching pipe 2a and the second liquid-side branching pipe 2b, and is then sent to the first indoor unit 30a and the second indoor unit 30b.

[0084] The refrigerant sent to the first indoor unit 30a is reduced in pressure by the first indoor expansion valve 36a to near the suction pressure of the compressor 12, becoming a gas-liquid two-phase refrigerant, and is sent to the first indoor heat exchanger 32a. In this embodiment, for example, during cooling operation, the valve opening of the first indoor expansion valve 36a is controlled so that the degree of superheating of the refrigerant suctioned by the compressor 12 satisfies predetermined conditions. Specifically, the degree of superheating determined from the pressure-equivalent saturation temperature grasped by the suction pressure sensor 23 and the refrigerant temperature detected by the suction temperature sensor 25 is controlled to satisfy predetermined conditions. The gas-liquid two-phase refrigerant evaporates in the first indoor heat exchanger 32a through heat exchange with the air in the conditioned space supplied to the first indoor heat exchanger 32a by the first indoor fan 34a, becoming a low-pressure gaseous refrigerant. This low-pressure gaseous refrigerant is sent from the first indoor unit 30a to the gas-side connecting pipe 4 via the first gas-side branch pipe 4a.

[0085] Furthermore, when the temperature detected by the first indoor temperature sensor 33a satisfies the conditions for the set temperature during cooling of the first indoor unit 30a, which are received by the operating remote control, etc., the first indoor unit 30a is controlled to enter a thermo-off state during cooling. Specifically, control is performed to set the valve opening of the first indoor expansion valve 36a of the first indoor unit 30a to a fully closed state. As a result, even when the thermo-off state is entered during cooling operation, evaporation of the refrigerant in the first indoor heat exchanger 32a is suppressed, and cold air is prevented from flowing out of the first indoor heat exchanger 32a into the room. The conditions for the set temperature are not particularly limited, and may include, for example, the temperature detected by the first indoor temperature sensor 33a reaching the set temperature, reaching a predetermined temperature exceeding the set temperature, or a predetermined time elapsed while the temperature was at the set temperature (the same applies hereinafter).

[0086] The liquid refrigerant sent to the second indoor unit 30b is the same as that in the first indoor unit 30a. In the second indoor expansion valve 36b, it is reduced to near the suction pressure of the compressor 12, becoming a gas-liquid two-phase refrigerant, which is then sent to the second indoor heat exchanger 32b. In this embodiment, during cooling operation, the valve opening of the second indoor expansion valve 36b is controlled so that the degree of superheating of the refrigerant suctioned by the compressor 12 satisfies predetermined conditions. Specifically, the degree of superheating determined from the pressure-equivalent saturation temperature determined by the suction pressure sensor 23 and the refrigerant temperature detected by the suction temperature sensor 25 is controlled to satisfy predetermined conditions. In the second indoor heat exchanger 32b, the gas-liquid two-phase refrigerant exchanges heat with the air in the conditioned space supplied to the second indoor heat exchanger 32b by the second indoor fan 34b, evaporates, and becomes a low-pressure gaseous refrigerant. This low-pressure gaseous refrigerant is sent from the second indoor unit 30b to the gas-side connecting pipe 4 via the second gas-side branch pipe 4b.

[0087] Furthermore, when the temperature detected by the second indoor temperature sensor 33b satisfies the conditions for the set temperature during cooling of the second indoor unit 30b, which are received via the operating remote control, the second indoor unit 30b is controlled to enter a thermo-off state during cooling. Specifically, control is performed to set the valve opening of the second indoor expansion valve 36b of the second indoor unit 30b to a fully closed state. As a result, even when the thermo-off state is entered during cooling operation, evaporation of the refrigerant in the second indoor heat exchanger 32b is suppressed, and the outflow of cold air from the second indoor heat exchanger 32b into the room is suppressed.

[0088] The refrigerant flowing through the gas-side connecting pipe 4 is sent to the outdoor unit 10, and flows into the accumulator 20 via the flow path switching valve 14. The low-pressure gaseous refrigerant that flows into the accumulator 20 is then drawn back into the compressor 12.

[0089] (2-3-2) Heating operation When the controller 70 receives an instruction to start heating operation, for example from the operating remote control via the indoor unit 30, it sets the flow path switching valve 14 to the second state and starts the operation of the compressor 12. In addition, based on the measurement results of sensors that measure the temperature and pressure of the refrigerant, which are provided in the refrigerant circuit 90, and the set temperature, the controller 70 appropriately controls the rotation speed of the compressor 12 motor and the opening degrees of the outdoor expansion valve 18, the first indoor expansion valve 36a, and the second indoor expansion valve 36b. During heating operation, the first gas side valve 37a and the second gas side valve 37b are controlled to be fully open.

[0090] The flow of refrigerant in the refrigerant circuit 90 will be explained.

[0091] When the compressor 12 is started, low-pressure gaseous refrigerant is drawn into the compressor 12 and compressed by the compressor 12 to become high-pressure gaseous refrigerant. The high-pressure gaseous refrigerant flows through the gas-side connecting pipe 4 via the flow path switching valve 14, and at the second branching point Y, it branches into the first gas-side branching pipe 4a and the second gas-side branching pipe 4b, thereby being sent to the first indoor unit 30a and the second indoor unit 30b.

[0092] The gaseous refrigerant sent to the first indoor unit 30a passes through the first gas-side valve 37a, which is controlled to be fully open, and is sent to the first indoor heat exchanger 32a. The refrigerant sent to the first indoor heat exchanger 32a exchanges heat with the air in the conditioned space supplied to the first indoor heat exchanger 32a by the first indoor fan 34a and dissipates heat. The temperature of the air supplied to the first indoor heat exchanger 32a rises as it exchanges heat with the refrigerant flowing through the first indoor heat exchanger 32a, and the heated air is blown out into the conditioned space. The refrigerant that has dissipated heat in the first indoor heat exchanger 32a is depressurized in the first indoor expansion valve 36a. In this embodiment, for example, during heating operation, the valve opening of the first indoor expansion valve 36a is controlled so that the degree of subcooling of the refrigerant flowing out of the outlet of the first indoor heat exchanger 32a satisfies a predetermined condition. Specifically, the degree of subcooling, determined from the pressure-equivalent saturation temperature obtained from the discharge pressure sensor 21 and the refrigerant temperature detected by the first indoor heat exchanger temperature sensor 35a, is controlled to satisfy predetermined conditions. The refrigerant, depressurized by the first indoor expansion valve 36a, is sent to the liquid-side connecting pipe 2 via the first liquid-side branch pipe 2a.

[0093] Furthermore, when the temperature detected by the first indoor temperature sensor 33a satisfies the conditions for the set temperature during heating of the first indoor unit 30a received by the operating remote control, etc., the first indoor unit 30a is controlled to enter a thermo-off state during heating. Specifically, the valve opening of the first indoor expansion valve 36a of the first indoor unit 30a is controlled to be in a predetermined slightly open state, which is an opening less than a predetermined slightly open degree, not a fully closed state. The predetermined slightly open degree is not particularly limited and may be, for example, a valve opening that results in a flow path area of ​​half or less of the flow path area of ​​the valve opening of the first indoor expansion valve 36a in its fully open state, or a valve opening that results in a flow path area of ​​1 / 3 or less, or a valve opening that results in a flow path area of ​​1 / 5 or less. As a result, even when the thermo-off state is entered during heating operation, a state in which refrigerant flow occurs in the first indoor heat exchanger 32a is maintained, thereby suppressing the accumulation of a large amount of liquid refrigerant in the first indoor heat exchanger 32a.

[0094] The gaseous refrigerant sent to the second indoor unit 30b is the same as the refrigerant sent to the first indoor unit 30a, and passes through the second gas-side valve 37b, which is controlled to be fully open, and is sent to the second indoor heat exchanger 32b. The refrigerant sent to the second indoor heat exchanger 32b exchanges heat with the air in the conditioned space supplied to the second indoor heat exchanger 32b by the second indoor fan 34b and dissipates heat. The temperature of the air supplied to the second indoor heat exchanger 32b rises as it exchanges heat with the refrigerant flowing through the second indoor heat exchanger 32b, and the heated air is blown out into the conditioned space. The refrigerant that has dissipated heat in the second indoor heat exchanger 32b is depressurized in the second indoor expansion valve 36b. In this embodiment, for example, during heating operation, the valve opening of the second indoor expansion valve 36b is controlled so that the degree of subcooling of the refrigerant flowing at the outlet of the second indoor heat exchanger 32b satisfies a predetermined condition. Specifically, the degree of subcooling, determined from the pressure-equivalent saturation temperature obtained from the discharge pressure sensor 21 and the refrigerant temperature detected by the second chamber heat exchanger temperature sensor 35b, is controlled to satisfy predetermined conditions. The refrigerant, depressurized by the second chamber expansion valve 36b, is sent to the liquid-side connecting pipe 2 via the second liquid-side branch pipe 2b.

[0095] Furthermore, when the temperature detected by the second indoor temperature sensor 33b satisfies the conditions for the set temperature during heating of the second indoor unit 30b received by the operating remote control, etc., the second indoor unit 30b is controlled to enter a thermo-off state during heating. Specifically, the valve opening of the second indoor expansion valve 36b of the second indoor unit 30b is controlled to be in a predetermined slightly open state, which is an opening less than a predetermined slightly open state, not a fully closed state. The predetermined slightly open state is not particularly limited and may be, for example, a valve opening that results in a flow path area of ​​half or less of the flow path area of ​​the valve opening of the second indoor expansion valve 36b in a fully open state, or a valve opening that results in a flow path area of ​​1 / 3 or less, or a valve opening that results in a flow path area of ​​1 / 5 or less. As a result, even when the thermo-off state is entered during heating operation, a state in which refrigerant flow occurs in the second indoor heat exchanger 32b is maintained, thereby suppressing the accumulation of a large amount of liquid refrigerant in the second indoor heat exchanger 32b.

[0096] The refrigerant flowing through the liquid side connecting pipe 2 is sent to the outdoor unit 10. In the outdoor unit 10, the refrigerant flowing through the liquid refrigerant pipe 28d is reduced in pressure by the outdoor expansion valve 18 to near the suction pressure of the compressor 12, becoming a gas-liquid two-phase refrigerant, which then flows into the outdoor heat exchanger 16. In this embodiment, for example, during heating operation, the valve opening of the outdoor expansion valve 18 is controlled so that the degree of superheating of the refrigerant suctioned by the compressor 12 satisfies predetermined conditions. Specifically, the degree of superheating determined from the pressure-equivalent saturation temperature grasped by the suction pressure sensor 23 and the refrigerant temperature detected by the suction temperature sensor 25 is controlled to satisfy predetermined conditions. The low-pressure gas-liquid two-phase refrigerant that flows into the outdoor heat exchanger 16 exchanges heat with the air surrounding the outdoor unit 10 supplied by the outdoor fan 22 and evaporates, becoming a low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant flows into the accumulator 20 via the flow path switching valve 14. The low-pressure gaseous refrigerant that flows into the accumulator 20 is then drawn back into the compressor 12.

[0097] (2-3-3) Overview of refrigerant leakage prevention treatment When the controller 70 detects a refrigerant leak using either the first refrigerant sensor 38a of the first indoor unit 30a (which is an indoor unit 30) or the second refrigerant sensor 38b of the second indoor unit 30b (which is also an indoor unit 30) (an example of a predetermined fully closed condition), it performs a refrigerant leak prevention process by controlling the indoor expansion valve 36 of the indoor unit 30 where the refrigerant leak is detected and the gas-side valve 37 of the indoor unit 30 where the refrigerant leak is detected to be in a fully closed state (an example of a second control), thereby blocking the inflow of refrigerant into the indoor heat exchanger 32 through the liquid-side connecting pipe 2 and the gas-side connecting pipe 4 to the indoor unit 30. However, in the case of the indoor expansion valve 36 of the indoor unit 30 where refrigerant leakage has been detected, in order to reduce the risk that foreign matter such as dust may get stuck between the valve seat and the valve body and prevent it from being fully closed, if the indoor expansion valve 36 has remained below a predetermined small opening (an example of a second predetermined opening) for a predetermined period of time (an example of a second predetermined period condition) or longer (an example of a pre-condition condition) (an example of a predetermined condition), then, before controlling it to a fully closed state, control is performed to increase the valve opening (an example of a first control) to ensure that no foreign matter is present in the vicinity.

[0098] Furthermore, even if a refrigerant leak is detected in any of the indoor units 30, the controller 70 will not stop the operation of the compressor 12 and will continue the cooling / heating operation in the indoor units 30 other than the one in which the refrigerant leak was detected. However, if a refrigerant leak is detected in any of the indoor units 30, the controller 70 may stop the operation of the compressor 12 and also stop the cooling / heating operation in the indoor units 30 other than the one in which the refrigerant leak was detected.

[0099] Furthermore, if the controller 70 detects a refrigerant leak in any of the indoor units 30 via the refrigerant sensor 38, it will, for example, notify the operating remote control of which indoor unit 30 the refrigerant leak has been detected from.

[0100] (3) Control flow for refrigerant leakage prevention treatment Figure 4 shows the control flowchart for the refrigerant leakage prevention process.

[0101] In step S1, the controller 70 performs normal operation. Specifically, the controller 70 performs cooling or heating operation on the refrigeration cycle device 100 so that the conditions for a predetermined set temperature are met. While performing normal control, the controller 70 stores in memory historical information of the control state of the valve openings of the first indoor expansion valve 36a and the second indoor expansion valve 36b.

[0102] In step S2, the controller 70 determines whether a refrigerant leak has been detected in any of the multiple indoor units 30. Specifically, the controller 70 determines whether a refrigerant leak has been detected by the first refrigerant sensor 38a or the second refrigerant sensor 38b. If a refrigerant leak is detected, the controller recognizes the indoor unit 30 equipped with the refrigerant sensor 38 that detected the leak as the leaking unit and proceeds with the processing from step S3 onward. If no refrigerant leak is detected, the process returns to step S1 and normal operation continues.

[0103] In step S3, the controller 70 identifies the indoor unit 30 where the refrigerant leak was detected and notifies the remote control and the controller 70 of the leak.

[0104] In step S4, the controller 70 recognizes the indoor unit 30 where a refrigerant leak has been detected as a leaking unit and controls the closing of the gas-side valve 37 of the leaking unit. Specifically, if a refrigerant leak is detected by the first refrigerant sensor 38a, the controller 70 recognizes the first indoor unit 30a as a leaking unit and controls the closing of the first gas-side valve 37a of the first indoor unit 30a. Also, if a refrigerant leak is detected by the second refrigerant sensor 38b, the controller 70 recognizes the second indoor unit 30b as a leaking unit and controls the closing of the second gas-side valve 37b of the second indoor unit 30b. Note that the first gas-side valve 37a and the second gas-side valve 37b are controlled to be fully open during both cooling and heating operations, and since the valve opening is not narrowed, a state is maintained in which there is a low possibility of foreign matter such as dust being present in the surroundings. Therefore, even if control is applied to close the first gas-side valve 37a or the second gas-side valve 37b, it is unlikely that foreign objects such as debris will get stuck between the valve seat and the valve body in the first gas-side valve 37a or the second gas-side valve 37b, and the reliability of the valve closing control is high.

[0105] In step S5, the controller 70 determines whether the indoor expansion valve 36 of the leaking indoor unit 30, which is the indoor unit where the refrigerant leak was detected, has remained below a predetermined small opening for a predetermined period of time or longer. Specifically, the controller 70 reads the control state history information of the valve opening of the indoor expansion valve 36 of the leaking unit, which is either the first indoor expansion valve 36a or the second indoor expansion valve 36b, from the memory and determines whether the state has remained below a predetermined small opening for a predetermined period of time or longer. For example, when the first indoor expansion valve 36a or the second indoor expansion valve 36b is subjected to control such as subcooling control or superheating control during cooling or heating operation, if the heat load processed by the first indoor heat exchanger 32a or the second indoor heat exchanger 32b remains small, the valve opening of the first indoor expansion valve 36a or the second indoor expansion valve 36b tends to be kept small, and the state of remaining below a predetermined small opening may continue for a predetermined period of time or longer. Furthermore, during heating operation, when the conditions for the set temperature during heating of the first indoor unit 30a are met, the first indoor unit 30a is controlled to enter a thermo-off state during heating, and the valve opening of the first indoor expansion valve 36a is controlled to a predetermined slightly open state, which is an opening less than a predetermined small opening, not a fully closed state. Similarly, during heating operation, when the conditions for the set temperature during heating of the second indoor unit 30b are met, the second indoor unit 30b is controlled to enter a thermo-off state during heating, and the valve opening of the second indoor expansion valve 36b is controlled to a predetermined slightly open state, which is an opening less than a predetermined small opening, not a fully closed state. Thus, if it is discovered from the control history that the valve opening of the indoor expansion valve 36 of the indoor unit 30, which has been found to have leaked refrigerant, has been continuously controlled to be partially closed, it is highly likely that foreign matter such as dirt is present around the indoor expansion valve 36. Therefore, the process proceeds to step S6, where control is performed to temporarily increase the valve opening of the indoor expansion valve 36. On the other hand, if there is no control history such as the valve opening being continuously controlled to be slightly closed for the indoor expansion valve 36 of the indoor unit 30 in which refrigerant leakage was found, the process proceeds to step S7.The predetermined period is not particularly limited and may be a predetermined length of time, or it may be the time required for the cumulative rotational speed of the compressor 12 to reach a predetermined number while the opening is less than a predetermined small opening.

[0106] In step S6, the controller 70 controls the indoor expansion valve 36 of the leaker, which is the indoor unit 30 where the refrigerant leak has been detected, to increase the valve opening degree beyond the current valve opening degree. Specifically, the controller 70 increases the valve opening degree of the indoor expansion valve 36 until it reaches a predetermined opening degree or greater. Here, the predetermined opening degree is not particularly limited and may be, for example, half-open or greater, which is half of the fully open state. In this embodiment, the state in which the valve opening degree of the indoor expansion valve 36 of the leaker is set to a predetermined opening degree or greater is maintained for a predetermined time. This predetermined time may be, for example, 0.5 seconds or more and 5 seconds or less, or 1 second or less, or it may be the time required to move the valve body to increase the valve opening degree by the predetermined amount. As a result, even if foreign matter such as dirt is present around the indoor expansion valve 36, it is possible to move the foreign matter to a location other than the indoor expansion valve 36, and even if the indoor expansion valve 36 is closed, a situation in which the indoor expansion valve 36 cannot be completely closed due to foreign matter getting stuck between the valve seat and the valve body is avoided. In addition, after the control to increase the valve opening of the indoor expansion valve 36 of the leak machine is performed in step S6, and before the control to fully close the indoor expansion valve 36 of the leak machine is started in step S7, no other control is performed for the valve opening of the indoor expansion valve 36 of the leak machine, and the control to fully close the indoor expansion valve 36 of the leak machine is started immediately after the control to increase the valve opening of the indoor expansion valve 36 of the leak machine. Furthermore, in this embodiment, when the control to increase the valve opening of the indoor expansion valve 36 is performed, if the compressor 12 is running, the rotational speed of the compressor 12 is reduced from the current level. Specifically, the rotational speed of the compressor 12 is reduced by an amount corresponding to the degree to which the valve opening of the indoor expansion valve 36 is increased from the current level.

[0107] In step S7, the controller 70 controls the indoor expansion valve 36 of the leaking indoor unit 30, which is the leak detection unit, to be in a fully closed state. If it is not determined in step S5 that "the state of being less than a predetermined small opening has continued for a predetermined period of time or longer", then it is considered unlikely that there is any foreign matter such as dirt around the indoor expansion valve 36, and the valve will be closed without performing the process of increasing the valve opening as in step S6.

[0108] In step S8, the controller 70 waits for a predetermined time to elapse.

[0109] In step S9, the controller 70 determines whether the refrigerant sensor 38 of the indoor unit 30, which was equipped with the refrigerant sensor 38 that detected the leak in step S2, has detected a refrigerant leak. Specifically, it determines whether the refrigerant leak is still continuing even after a predetermined time has elapsed since the control to fully close the indoor expansion valve 36 in step S7. This makes it possible to determine whether the refrigerant leak has been stopped more reliably. If a refrigerant leak is detected, the process proceeds to step S10. If no refrigerant leak is detected, the process returns to step S1, and normal operation of the indoor units 30 other than the leaking unit continues.

[0110] In step S10, the controller 70 controls the indoor expansion valve 36 of the leaker to open beyond its current position, similar to step S6. This makes it possible to more reliably move foreign matter, such as debris, away from the indoor expansion valve 36 of the leaker, even if such foreign matter is interposed between the valve body and the valve seat, although the possibility is lower than in step S6.

[0111] In step S11, the controller 70 controls the indoor expansion valve 36 of the leaker to be in a fully closed state.

[0112] (4) Features of the Embodiment According to the refrigeration cycle device 100 of this embodiment, when attempting to close the indoor expansion valve 36, it is possible to increase the valve opening before initiating control to bring it to a fully closed state. Therefore, when closing the indoor expansion valve 36, the presence of foreign matter such as dirt around the indoor expansion valve 36 can cause the foreign matter to get stuck in the gap between the valve body and the valve seat, preventing the valve from being fully closed. This improves the reliability of the control to bring the indoor expansion valve 36 to a fully closed state.

[0113] Furthermore, since the indoor expansion valves 36a and 36b can be more reliably closed by avoiding situations where foreign objects get stuck, when a refrigerant leak is detected by the refrigerant sensors 38a and 38b, the supply of refrigerant passing through the indoor expansion valves 36a and 36b to the corresponding indoor heat exchangers 32a and 32b is suppressed, making it possible to keep the amount of refrigerant leakage small.

[0114] Furthermore, the control to increase the valve opening of the indoor expansion valves 36a and 36b is limited to cases where the indoor expansion valves 36a and 36b have remained below a predetermined minute opening for a predetermined period of time or longer before the control to set them to a fully closed state is disclosed. As a result, in cases where the valve opening of the indoor expansion valves 36a and 36b was greater than or equal to a minute opening shortly before the control to set them to a fully closed state was disclosed, or in other cases where the possibility of foreign matter being present around the indoor expansion valves 36a and 36b is low, it is possible to quickly set them to a fully closed state without performing the control to increase the valve opening, and moreover, a situation in which refrigerant leaks out of the valves can be avoided.

[0115] Furthermore, in this embodiment, the indoor expansion valves 36a and 36b can implement two functions: a flow control valve for controlling the amount of refrigerant sent to the indoor heat exchangers 32a and 32b when circulating refrigerant in the refrigerant circuit 90 to perform a refrigeration cycle, and a shut-off valve for shutting off the flow of refrigerant when a refrigerant leak is detected. This eliminates the need to separately provide a shut-off valve for shutting off the flow of refrigerant in addition to the indoor expansion valves 36a and 36b.

[0116] Furthermore, in the refrigeration cycle device 100 of this embodiment, carbon dioxide refrigerant is used as the refrigerant. When using carbon dioxide refrigerant, even at low concentrations, the risk due to toxicity tends to be a problem compared to R32 or propane, but in this embodiment, the reliability of the control that keeps the indoor expansion valve 36 in a fully closed state is high, so it is possible to more reliably suppress the leakage of carbon dioxide refrigerant and reduce the risk due to the toxicity of the leaked refrigerant.

[0117] Furthermore, in the refrigeration cycle device 100 of this embodiment, carbon dioxide is used as the refrigerant, and when the refrigeration cycle is performed, the refrigerant pressure on the high-pressure side is used at a high level. For this reason, in the refrigeration cycle device 100 of this embodiment that uses carbon dioxide as the refrigerant, the refrigerant piping and heat transfer tubes that constitute the refrigerant circuit 90 are designed to have a high design pressure and are made of thick-walled materials. In this case, the amount of heat input required when brazing the piping tends to be large, and as a result, an oxide film is likely to form on the inner surface of the piping. Therefore, when the refrigeration cycle is performed, this oxide film is likely to peel off from the inner surface of the piping and become trapped between the valve body and valve seat of the expansion valve along with foreign matter such as dirt and refrigerant. Even in this case, by controlling the valve opening to increase the degree of opening as described above, the situation in which foreign matter such as dirt and refrigerant gets trapped between the valve seat and valve body is suppressed.

[0118] Furthermore, in refrigeration cycle systems that use carbon dioxide as a refrigerant, the refrigerant pressure tends to be high when the refrigeration cycle is performed, and if the refrigerant leaks, the amount of leakage may be large due to the pressure difference. In contrast, in the refrigeration cycle system 100 of this embodiment, by controlling the valve opening as described above, the situation in which foreign matter such as dirt gets stuck between the valve seat and the valve body when the indoor expansion valve 36 is controlled to a fully closed state is suppressed, and thus the leakage of carbon dioxide refrigerant can be suppressed more reliably.

[0119] (5) Other embodiments (5-1) Other Embodiments A In the above embodiment, when a refrigerant leak is detected and the indoor expansion valve 36 is controlled to a fully closed state, the case in which the valve opening of the indoor expansion valve 36 is increased before the control to fully close the valve was explained as an example.

[0120] In contrast, when the control to increase the valve opening of the indoor expansion valve 36 is performed before controlling the indoor expansion valve 36 to a fully closed state, this control may be performed not only when a refrigerant leak is detected, but also, in addition to or instead of when a refrigerant leak is detected, when the indoor expansion valve 36 of the indoor unit 30 that has entered a thermo-off state during cooling operation is controlled to a fully closed state, the control to increase the valve opening of the indoor expansion valve 36 may be performed before the control to fully close the indoor expansion valve 36.

[0121] Figure 5 shows an example of a control flowchart for controlling the indoor expansion valve 36 to a fully closed state during such cooling operation.

[0122] In step S21, the controller 70 performs cooling operation as normal operation. Specifically, the controller 70 performs cooling operation on the refrigeration cycle device 100 so that the conditions for a predetermined set temperature are met. Here, the controller 70 controls the valve openings of the first indoor expansion valve 36a and the second indoor expansion valve 36b so that the superheating degree of the refrigerant drawn in by the compressor 12 meets predetermined conditions, and stores the history information of this control state in memory.

[0123] In step S22, the controller 70 determines whether any of the multiple indoor units 30 meet the conditions for the set temperature during cooling operation. Specifically, the controller 70 determines whether the conditions for the set temperature are met for each indoor unit 30 based on the set temperature for cooling operation received from the operating remote control, etc., and the temperature detected by the indoor temperature sensor 33. If there is an indoor unit 30 that meets the conditions for the set temperature, the controller recognizes that indoor unit 30 as a cooling thermo-off unit and proceeds with the processing from step S23 onwards. If there is no indoor unit 30 that meets the conditions for the set temperature, the process returns to step S21 and continues the cooling operation.

[0124] In step S23, the controller 70 determines whether the indoor expansion valve 36 of the indoor unit 30, which is a cooling thermo-off unit, has remained below a predetermined small opening for a predetermined period of time or longer. Specifically, the controller 70 reads the control state history information of the valve opening from memory for the indoor expansion valve 36 of the cooling thermo-off unit, which is either the first indoor expansion valve 36a or the second indoor expansion valve 36b, and determines whether it has remained below a predetermined small opening for a predetermined period of time or longer. For example, when superheat control or other control is performed on the first indoor expansion valve 36a or the second indoor expansion valve 36b during cooling operation, if the heat load processed by the first indoor heat exchanger 32a or the second indoor heat exchanger 32b remains small, the valve opening of the first indoor expansion valve 36a or the second indoor expansion valve 36b tends to be kept small, and it is possible that it remains below a predetermined small opening for a predetermined period of time or longer. Thus, if the control history reveals that the indoor expansion valve 36 of the indoor unit 30, which is a cooling thermo-off unit, has been continuously controlled to a closed position, it is highly likely that there is foreign matter such as dust around the indoor expansion valve 36. Therefore, the process proceeds to step S24, where control is performed to temporarily increase the valve opening of the indoor expansion valve 36. On the other hand, if there is no control history indicating that the indoor expansion valve 36 of the indoor unit 30, which is a cooling thermo-off unit, has been continuously controlled to a closed position, the process proceeds to step S25. The predetermined period is not particularly limited and may be a predetermined length of time, or it may be the time required for the cumulative rotational speed of the compressor 12 to reach a predetermined number while the valve opening is less than a predetermined small opening.

[0125] In step S24, the controller 70 controls the indoor expansion valve 36 of the indoor unit 30, which is a cooling thermo-off unit, to increase its valve opening beyond its current position. Specifically, the controller 70 increases the valve opening of the indoor expansion valve 36 until it reaches a predetermined opening or greater. The predetermined opening is not particularly limited and may be, for example, half-open or greater, which is half of the fully open state. The state in which the valve opening of the indoor expansion valve 36 of the cooling thermo-off unit is at or above the predetermined opening is maintained for, for example, a predetermined time. This predetermined time may be, for example, 0.5 seconds or more and 5 seconds or less, or 1 second or less, or it may be the time required to move the valve body to increase the valve opening by the predetermined amount. As a result, even if foreign matter such as dirt is present around the indoor expansion valve 36, it is possible to move the foreign matter to a location other than the indoor expansion valve 36, and even if the indoor expansion valve 36 is closed, a situation in which the indoor expansion valve 36 cannot be completely closed due to foreign matter getting stuck between the valve seat and the valve body is avoided. In addition, after the control to increase the valve opening of the indoor expansion valve 36 of the leaker is performed in step S24, and before the control to fully close the indoor expansion valve 36 of the leaker is started in step S25, no different control is performed for the valve opening of the indoor expansion valve 36 of the cooling thermo-off unit, and the control to fully close the indoor expansion valve 36 of the cooling thermo-off unit is started immediately after the control to increase the valve opening of the indoor expansion valve 36 of the cooling thermo-off unit. Furthermore, when the control to increase the valve opening of the indoor expansion valve 36 is performed, if the compressor 12 is running, control is performed to reduce its rotational speed from the current level. Specifically, the rotational speed of the compressor 12 is reduced by an amount corresponding to the degree to which the valve opening of the indoor expansion valve 36 is increased from its current position.

[0126] In step S25, the controller 70 controls the indoor expansion valve 36 of the indoor unit 30, which is a cooling thermo-off unit, to a fully closed state. If it is not determined in step S23 that "the state of being less than a predetermined small opening has continued for a predetermined period of time or longer", then it is considered unlikely that there is any foreign matter such as dirt around the indoor expansion valve 36, and the valve will be closed without performing a process to increase the valve opening as in step S24.

[0127] In step S26, the controller 70 determines whether the indoor unit 30 of the cooling thermo-off unit is in a state where it does not meet the conditions for the set temperature during cooling operation. Specifically, the controller 70 determines whether the indoor unit 30 of the cooling thermo-off unit is in a state where it does not meet the conditions for the set temperature, based on the set temperature during cooling operation and the temperature detected by the indoor temperature sensor 33. If it is determined that the conditions for the set temperature are not met, the controller returns to step S21 and restarts the cooling operation, which is the normal control, for the indoor unit 30 that was previously in a cooling thermo-off state.

[0128] Through the above control, the decrease in temperature of the indoor heat exchanger 32 of the indoor unit 30, which is in a thermo-off state during cooling operation, is suppressed, and the outflow of cold air from the indoor heat exchanger 32 towards the air-conditioned space is more reliably suppressed.

[0129] (5-2) Other Embodiments B Furthermore, the control to increase the valve opening of the indoor expansion valve 36 before controlling it to a fully closed state may be performed, for example, when starting a pump-down operation for the refrigeration cycle device 100, instead of or in addition to the above examples.

[0130] Pump-down operation is an operation in which the indoor expansion valves 36a and 36b of each indoor unit 30a and 30b are controlled to be in a fully closed state, while the compressor 12 is driven to make the outdoor heat exchanger 16 function as a refrigerant heat exchanger. This recovers the refrigerant from the refrigerant circuit 90 by collecting the refrigerant that has been heated from the indoor expansion valves 36a and 36b into the outdoor heat exchanger 16.

[0131] The refrigeration cycle device 100 may, for example, receive an instruction to start a pump-down operation when a predetermined button provided on the refrigeration cycle device 100 is pressed, or it may receive an instruction to start a pump-down operation via operation input from a remote control. In addition, the pump-down operation may be started when a refrigerant leak is detected by either the first refrigerant sensor 38a or the second refrigerant sensor 38b described above. In this case, the control of the pump-down operation described below may be applied instead of the control of the first chamber expansion valve 36a, the second chamber expansion valve 36b, the first gas-side valve 37a, and the second gas-side valve 37b in the above embodiment.

[0132] Upon receiving the command to start the pump-down operation, the controller 70 maintains the connection state of the flow path switching valve 14 if cooling operation was being performed, and switches the connection state of the flow path switching valve 14 to the cooling operation connection state if heating operation was being performed, and starts the pump-down operation. Here, if there are any indoor expansion valves 36a and 36b that have remained below a predetermined small opening for a predetermined period of time or longer at the time the pump-down operation is started, the controller 70 controls the valve opening to be increased above the current valve opening, as in the above embodiment, and then controls it to be in a fully closed state. Here, the outdoor expansion valve 18 is maintained in a state that is not fully closed, such as a fully open state. The controller 70 maintains the first gas side valve 37a and the second gas side valve 37b in a fully open state, starts the pump-down operation, and when the predetermined recovery completion conditions are met after refrigerant recovery is completed, controls the first gas side valve 37a and the second gas side valve 37b to be in a fully closed state. These recovery termination conditions are not particularly limited and may include situations such as the cumulative operating time from the start of the pump-down operation reaching a predetermined time, or the superheating of the refrigerant intake of the compressor 12 exceeding a predetermined value. After that, the drive of the compressor 12 is stopped, and the pump-down operation is terminated.

[0133] With the above control, it becomes possible to more reliably suppress the leakage of refrigerant from the indoor expansion valves 36a and 36b to the indoor heat exchangers 32a and 32b during pump-down operation.

[0134] (5-3) Other Embodiments C In the above embodiment, carbon dioxide refrigerant was used as an example of the refrigerant used to fill the refrigerant circuit 90.

[0135] In contrast, the refrigerant used in the refrigerant circuit 90 is not limited to this, and may be R32 or propane, for example.

[0136] Although R32 and propane are flammable, more effectively suppressing the leakage of these refrigerants can reduce the risk of combustion caused by leaked refrigerants.

[0137] (5-4) Other Embodiments D In the above embodiment, the case in which gas side valves 37a and 37b are provided in indoor units 30a and 30b was described as an example.

[0138] In contrast, the gas-side valves 37a and 37b do not necessarily have to be present in the indoor units 30a and 30b. For example, a valve unit having the gas-side valves 37a and 37b may be provided as a separate unit from the indoor units 30a and 30b.

[0139] <Other> While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. [Explanation of symbols]

[0140] 2: Liquid-side connecting piping (first main channel, first channel) 2a: First liquid-side branch piping (first branch channel, first channel) 2b: Second liquid-side branch piping (second branch channel, first channel) 4: Gas-side connecting piping (second main flow path, second flow path) 4a: First gas-side branch piping (third branch channel, second channel) 4b: Second gas-side branch piping (fourth branch channel, second channel) 10: Outdoor unit 12: Compressor 14: Flow path switching valve 16:Outdoor heat exchanger 18: Outdoor expansion valve 20: Accumulator 21: Discharge pressure sensor 22: Outdoor fan 23: Intake pressure sensor 24: Liquid shut-off valve 25: Intake temperature sensor 26: Gas shut-off valve 27: Outdoor heat exchanger temperature sensor 28a: Inhalation tube (second main channel, second channel) 28b: Discharge pipe (second main flow path, second flow path) 28c: First gas refrigerant piping (second main channel, second channel) 28d: Liquid refrigerant piping 28e: Second gas refrigerant piping (second main channel, second channel) 30: Indoor Unit 30a: First indoor unit 30b: Second indoor unit 31a: First casing 31b: Second casing 32: Indoor heat exchanger 32a: 1st indoor heat exchanger 32b: 2nd indoor heat exchanger 33a: First indoor temperature sensor 33b: Second indoor temperature sensor 34a: First indoor fan 34b: Second indoor fan 35a: First indoor heat exchanger temperature sensor 35b: Second indoor heat exchanger temperature sensor 36: Indoor expansion valve (electric expansion valve) 36a: First chamber expansion valve (electric expansion valve, first electric expansion valve) 36b: Second chamber expansion valve (electric expansion valve, second electric expansion valve) 37: Gas side valve 37a: First gas side valve 37b: Second gas side valve 38: Refrigerant sensor 38a: First refrigerant sensor (leak detection unit) 38b: Second refrigerant sensor (leak detection unit) 70: Controller (control unit) 72: Indoor Control Unit 72a: First Indoor Control Unit 72b: Second Room Control Unit 74: Outdoor control unit 90: Refrigerant Circuit 100: Refrigeration cycle equipment X: First branching point Y: Second branching point [Prior art documents] [Patent Documents]

[0141] [Patent Document 1] Japanese Patent Publication No. 2016-035356

Claims

1. It has an electrically operated expansion valve (36a, 36b), and a refrigerant circuit (90) through which the refrigerant circulates, A control unit (70) that controls the opening degree of the electric expansion valve, Equipped with, The control unit, upon meeting predetermined conditions including a predetermined fully closed condition, performs a first control to increase the valve opening of the electric expansion valve, and then performs a second control to fully close the electric expansion valve. Refrigeration cycle device (100).

2. In the first control, the control unit maintains the state in which the valve opening of the electric expansion valve is greater than or equal to a first predetermined opening until the first predetermined period condition is met, and immediately after performing the first control, it performs the second control. The refrigeration cycle apparatus according to claim 1.

3. The aforementioned predetermined conditions include a prior state condition that the valve opening of the electric expansion valve is less than a second predetermined opening for a period of time or longer that satisfies the second predetermined period condition. A refrigeration cycle apparatus according to claim 1 or 2.

4. The control unit controls the valve opening of the electric expansion valve to be less than the second predetermined opening when the heat load to be processed is in a predetermined low load state. The refrigeration cycle apparatus according to claim 3.

5. The refrigerant circuit includes a compressor (12), an outdoor heat exchanger (16), indoor heat exchangers (32a, 32b), a first flow path (2, 2a, 2b) extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with the electric expansion valve, and a second flow path (4, 4a, 4b, 28e, 28a, 28b, 28c) extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with the compressor. The refrigerant circuit is capable of performing a heating operation in which the indoor heat exchanger functions as a heat radiator for the refrigerant. The control unit controls the electric expansion valve so that, when the conditions for the set temperature corresponding to the indoor heat exchanger are met, the valve opening is less than the second predetermined opening and not in a fully closed state. The refrigeration cycle apparatus according to claim 3.

6. The refrigerant circuit includes a compressor (12), an outdoor heat exchanger (16), indoor heat exchangers (32a, 32b), a first flow path (2, 2a, 2b) extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with the electric expansion valve, and a second flow path (4, 4a, 4b, 28e, 28a, 28b, 28c) extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with the compressor. The refrigerant circuit is capable of performing cooling operation by making the indoor heat exchanger function as an evaporator for the refrigerant. The control unit satisfies the predetermined fully closed condition when the conditions relating to the set temperature corresponding to the indoor heat exchanger are met. The refrigeration cycle apparatus according to claim 3.

7. The refrigerant circuit comprises a compressor (12), an outdoor heat exchanger (16), a first indoor heat exchanger (32a), a second indoor heat exchanger (32b), a first electric expansion valve (36a) which is the electric expansion valve, a second electric expansion valve (36b) which is the electric expansion valve, a first main flow path (2) extending from the outdoor heat exchanger to a first branch section (X), and a first branch flow path (2a) extending from the first branch section to the first indoor heat exchanger and equipped with the first electric expansion valve. The system includes a second branch passage (2b) extending from the first branch to the second indoor heat exchanger and equipped with the second electric expansion valve, a second main passage (4, 28e, 28a, 28b, 28c) extending from the outdoor heat exchanger to the second branch (Y) and equipped with the compressor, a third branch passage (4a) extending from the second branch to the first indoor heat exchanger, and a fourth branch passage (4b) extending from the second branch to the second indoor heat exchanger. The refrigeration cycle apparatus according to claim 3.

8. The refrigerant circuit is capable of performing a heating operation in which the first indoor heat exchanger and the second indoor heat exchanger function as heat radiators for the refrigerant. The control unit controls the valve opening of the first electric expansion valve to be less than the second predetermined opening and not fully closed when the conditions for the set temperature corresponding to the first indoor heat exchanger are met, and controls the valve opening of the second electric expansion valve to be less than the second predetermined opening and not fully closed when the conditions for the set temperature corresponding to the second indoor heat exchanger are met. The refrigeration cycle apparatus according to claim 7.

9. The refrigerant circuit is capable of performing a cooling operation in which the first indoor heat exchanger and the second indoor heat exchanger function as evaporators for the refrigerant. The first electric expansion valve satisfies the predetermined fully closed condition when the conditions relating to the set temperature corresponding to the first indoor heat exchanger are met. The second electric expansion valve satisfies the predetermined fully closed condition when the conditions relating to the set temperature corresponding to the second indoor heat exchanger are met. The refrigeration cycle apparatus according to claim 7.

10. The system further includes leak detection units (38a, 38b) for detecting the refrigerant leaking from the refrigerant circuit, The predetermined fully closed condition includes the detection of a refrigerant leak by the leak detection unit. A refrigeration cycle apparatus according to claim 1 or 2.

11. If the predetermined fully closed condition is met without satisfying the prior state condition, the control unit performs the second control without performing the first control. The refrigeration cycle apparatus according to claim 3.

12. The refrigerant circuit includes a compressor (12), an outdoor heat exchanger (16), indoor heat exchangers (32a, 32b), a first flow path (2, 2a, 2b) extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with the electric expansion valve, and a second flow path (4, 4a, 4b, 28e, 28a, 28b, 28c) extending from the outdoor heat exchanger to the indoor heat exchanger and equipped with the compressor. The control unit is capable of pump-down operation control, which keeps the electric expansion valve fully closed while the outdoor heat exchanger functions as a heat radiator for the refrigerant. The aforementioned predetermined conditions are met when the pump-down operation control is initiated. A refrigeration cycle apparatus according to claim 1 or 2.

13. In the first control, the control unit increases the valve opening of the electric expansion valve to half open or more. A refrigeration cycle apparatus according to claim 1 or 2.

14. The refrigerant is a refrigerant that possesses at least one of a predetermined toxicity and a predetermined flammability. A refrigeration cycle apparatus according to claim 1 or 2.

15. The aforementioned refrigerant is carbon dioxide refrigerant. A refrigeration cycle apparatus according to claim 1 or 2.

16. A method for controlling the electric expansion valves (36a, 36b) of a refrigeration cycle device (100), The refrigeration cycle device includes a refrigerant circuit (90) through which the refrigerant circulates, which has the electric expansion valve, and a control unit (70) which controls the opening degree of the electric expansion valve. The control unit, upon meeting predetermined conditions including a predetermined fully closed condition, performs a first control to increase the valve opening of the electric expansion valve, and then performs a second control to fully close the electric expansion valve. Control method for an electric expansion valve.

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