JP7488478B2 - Refrigeration cycle device and method for determining refrigerant leakage - Google Patents

Description

This relates to a refrigeration cycle device and a method for determining refrigerant leakage.

Conventionally, as in Patent Document 1 (JP Patent Publication 2006-23072 A), there is known an air conditioner that forcibly performs cooling operation and determines whether or not there is a refrigerant leak based on the degree of subcooling when the condensation pressure, evaporation pressure, and degree of superheat of the refrigeration cycle are controlled to predetermined values.

However, even when refrigeration cycle devices of the same capacity are operated under similar conditions, the state of the refrigerant at a given point in the refrigerant circuit may change depending on the length of the connecting pipe. Therefore, even if a detection method can accurately detect refrigerant leakage when the length of the connecting pipe is a certain length, the accuracy of refrigerant leakage detection may decrease when the length of the connecting pipe is different.

The refrigeration cycle device according to the first aspect includes a refrigerant circuit, a sensor, and a control unit. The refrigerant circuit has a communication pipe that connects a heat source unit and a utilization unit. The sensor measures the temperature or pressure of the refrigerant at a predetermined location in the refrigerant circuit. The control unit determines whether or not there is refrigerant leakage from the refrigerant circuit based on the measurement value of the sensor. When the length of the communication pipe satisfies a predetermined condition, the control unit executes a first mode in which the presence or absence of refrigerant leakage from the refrigerant circuit is determined by a first method. When the length of the communication pipe does not satisfy the predetermined condition, the control unit executes a second mode in which the presence or absence of refrigerant leakage from the refrigerant circuit is determined by a second method different from the first method.

In the refrigeration cycle device of the first aspect, by using different detection methods depending on the length of the connecting pipe, refrigerant leakage can be detected with high accuracy regardless of the length of the connecting pipe.

The refrigeration cycle device according to the second aspect is the refrigeration cycle device according to the first aspect, and the predetermined condition is that the length of the connecting pipe is shorter than a threshold value.

In the refrigeration cycle device of the second aspect, the detection method used is changed depending on whether the connecting pipe is short or long, making it possible to accurately detect refrigerant leakage regardless of the connecting pipe length.

The refrigeration cycle device according to the third aspect is the refrigeration cycle device according to the first or second aspect, and the sensor includes a first sensor and a second sensor different from the first sensor. In the first mode, the control unit determines whether or not there is a refrigerant leak from the refrigerant circuit based on the measurement value of the first sensor. In the second mode, the control unit determines whether or not there is a refrigerant leak from the refrigerant circuit based on the measurement value of the second sensor.

In the refrigeration cycle device of the third aspect, refrigerant leakage is detected based on the measurement values of sensors that differ depending on the length of the connecting pipe, so that refrigerant leakage can be detected with high accuracy regardless of the length of the connecting pipe.

The refrigeration cycle device according to the fourth aspect is a refrigeration cycle device according to any one of the first aspect to the third aspect, and the first method is capable of detecting a smaller amount of refrigerant leakage than the second method.

In the refrigeration cycle device of the fourth aspect, when the length of the connecting pipe satisfies a predetermined condition, the first method can be used to accurately detect refrigerant leakage from the refrigerant circuit.

The refrigeration cycle device according to the fifth aspect is the refrigeration cycle device according to any one of the first aspect to the fourth aspect, in which the refrigerant circuit has a compressor, a condenser, and an evaporator connected by a refrigerant pipe. The control unit detects the degree of supercooling of the refrigerant at the outlet of the condenser and a first degree of superheat based on the measurement value of the sensor. The first degree of superheat is either the discharge superheat of the refrigerant at the compressor or the superheat of the refrigerant at the outlet of the evaporator. In the first mode, the control unit controls the operation of the refrigeration cycle device so that the degree of supercooling becomes a target value, and if the first degree of superheat exceeds a first value before the degree of supercooling becomes the target value, the control unit lowers the target value of the degree of supercooling, and if the target value becomes a value lower than the initial target value by a second value or more, determines that the refrigerant is leaking.

In the refrigeration cycle device of the fifth aspect, by using this method when the length of the connecting pipe satisfies a predetermined condition, refrigerant leakage can be detected with high accuracy.

The refrigeration cycle device according to the sixth aspect is a refrigeration cycle device according to any one of the first aspect to the fifth aspect, further comprising an acquisition unit that acquires information regarding the length of the communication pipe.

In the refrigeration cycle device of the sixth aspect, refrigerant leakage can be detected with high accuracy by changing the detection method depending on the actual length of the interconnecting pipe acquired by the acquisition unit.

The refrigeration cycle device according to the seventh aspect is a refrigeration cycle device according to any one of the first to sixth aspects, which is a chargeless type in which a predetermined amount of refrigerant is filled in the heat source unit in advance.

In the refrigeration cycle device of the seventh aspect, a predetermined amount of refrigerant is charged in advance, so depending on the length of the connecting pipe, a state in which there is a relatively large amount of surplus refrigerant and a state in which there is a relatively small amount of surplus refrigerant may occur. In contrast, in the refrigeration cycle device of the present disclosure, refrigerant leakage can be detected with high accuracy by changing the detection method depending on the length of the connecting pipe.

The method for determining refrigerant leakage according to the eighth aspect is a method in a refrigeration cycle device including a refrigerant circuit having a communication pipe connecting a heat source unit and a utilization unit, a sensor that measures the temperature or pressure of the refrigerant at a predetermined location in the refrigerant circuit, and a control unit, in which the control unit determines whether or not there is refrigerant leakage from the refrigerant circuit based on the measurement value of the sensor. The method for determining refrigerant leakage includes a step in which the control unit determines whether or not there is refrigerant leakage from the refrigerant circuit by a first method if the length of the communication pipe satisfies the predetermined condition, and a step in which the control unit determines whether or not there is refrigerant leakage from the refrigerant circuit by a second method different from the first method if the length of the communication pipe does not satisfy the predetermined condition.

The method for determining refrigerant leakage according to the eighth aspect uses different detection methods depending on the length of the interconnecting pipe, so refrigerant leakage can be detected with high accuracy regardless of the length of the interconnecting pipe.

The method for determining a refrigerant leak according to the ninth aspect is the method for determining a refrigerant leak according to the eighth aspect, and further includes a step in which an acquisition unit of the refrigeration cycle device acquires information regarding the length of the communication pipe when the control unit and a monitoring device that receives a refrigerant leak notification output by the control unit when the control unit determines that a refrigerant leak is occurring from the refrigerant circuit are communicably connected.

In the method for determining a refrigerant leak according to the ninth aspect, a refrigerant leak can be detected with high accuracy by changing the detection method depending on the actual length of the interconnecting pipe acquired by the acquisition unit.

1 is a schematic diagram of an air-conditioning apparatus, which is an example of a refrigeration cycle apparatus. FIG. 2 is a block diagram of the air conditioner and the air conditioner monitoring device of FIG. 1 . 4 is a flowchart of a process executed by a control unit of the air conditioning apparatus of FIG. 1 when determining the presence or absence of a refrigerant leak using a first method. 10 is a flowchart of a process executed by a control unit of the air conditioning apparatus of FIG. 1 when determining the presence or absence of a refrigerant leak using a second method. 4 is a flowchart of a process executed by a control unit of the air conditioning apparatus of FIG. 1 when determining a mode for determining the presence or absence of a refrigerant leak. FIG. 2 is a schematic configuration diagram of another example of an air conditioning apparatus, which is an example of a refrigeration cycle apparatus.

The refrigeration cycle device disclosed herein will be explained with reference to the drawings.

(1) Overall Configuration An air conditioning apparatus 100, which is an example of a refrigeration cycle apparatus of the present disclosure, and a monitoring device 200 that manages the air conditioning apparatus 100 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic configuration diagram of the air conditioning apparatus 100. Fig. 2 is a block diagram of the air conditioning apparatus 100 and the monitoring device 200 for the air conditioning apparatus 100.

The air conditioning device 100 is a device that performs a vapor compression refrigeration cycle and cools and heats the space to be air-conditioned. Note that the air conditioning device 100 does not have to be a device that performs both cooling and heating, and may be a device that performs only one of cooling and heating. Note that when the air conditioning device 100 performs only one of cooling and heating, the air conditioning device 100 does not have to have a flow path switching mechanism 22 described below.

The refrigeration cycle device of the present disclosure is not limited to an air conditioner, but may be a device other than an air conditioner that performs a vapor compression refrigeration cycle. For example, the refrigeration cycle device of the present disclosure may be a refrigeration cycle device for a refrigerator or freezer used to store food, etc., a hot water supply device, or a floor heating device.

The monitoring device 200 is a device owned by the manager of the air conditioning device 100 (for example, the owner of the air conditioning device 100 or a maintenance company commissioned to maintain the air conditioning device 100) and monitors the status of the air conditioning device 100. The air conditioning device 100 reports the operating status and abnormalities of the air conditioning device 100 to the monitoring device 200 via a network NW such as the Internet. In other words, when the control unit 52 determines that a refrigerant leak is occurring from the refrigerant circuit 10, the monitoring device 200 accepts a refrigerant leakage notification output by the control unit 52. The manager of the air conditioning device 100 can obtain the operating status and abnormalities of the air conditioning device 100 from the monitoring device 200.

The air conditioning device 100 mainly comprises one heat source unit 2, one utilization unit 4, a liquid refrigerant connection pipe 6, a gas refrigerant connection pipe 8, and a control unit 50 (see Figures 1 and 2). The liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 are examples of connection pipes. The liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 connect the heat source unit 2 and the utilization unit 4. The liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 are installed at the installation site of the air conditioning device 100. The control unit 50 controls the operation of various devices of the heat source unit 2 and the utilization unit 4. The control unit 50 also determines whether there is a refrigerant leak from the refrigerant circuit 10, which will be described later.

In this embodiment, the air conditioning device 100 has one utilization unit 4, but the air conditioning device 100 may have two or more utilization units 4 connected in parallel to each other. Also, while the air conditioning device 100 has one heat source unit 2, the air conditioning device 100 may have two or more heat source units 2.

The heat source unit 2 and the utilization unit 4 are connected via a liquid refrigerant connection pipe 6 and a gas refrigerant connection pipe 8 to form a refrigerant circuit 10 in which the refrigerant circulates (see FIG. 1). In other words, the refrigerant circuit 10 has a liquid refrigerant connection pipe 6 and a gas refrigerant connection pipe 8 as connection pipes connecting the heat source unit 2 and the utilization unit 4. The refrigerant circuit 10 is formed by connecting the compressor 21, the first heat exchanger 23, the first expansion valve 25, and the second expansion valve 26 of the heat source unit 2 and the second heat exchanger 41 of the utilization unit 4 with refrigerant pipes (see FIG. 1).

The refrigerant used in the air conditioning device 100 is, but is not limited to, an HFC (hydrofluorocarbon) refrigerant such as R32. HFC refrigerants do not have an ozone layer depletion effect, but have a relatively large global warming potential.

Although not limited thereto, the air conditioning apparatus 100 of this embodiment is a chargeless type refrigeration cycle apparatus. In the air conditioning apparatus 100, which is a chargeless type refrigeration cycle apparatus, a predetermined amount of refrigerant is pre-filled into the heat source unit 2 before the air conditioning apparatus 100 is transported to the installation site (e.g., at the time of shipment from the factory). In the air conditioning apparatus 100, which is a chargeless type refrigeration cycle apparatus, additional refrigerant is not normally filled (charged) into the refrigerant circuit 10 at the installation site of the air conditioning apparatus 100.

The amount of refrigerant to be filled in the heat source unit 2 in advance (the above-mentioned predetermined amount) is determined according to the capacity of the heat source unit 2, etc., so that there is no shortage of refrigerant during operation of the air conditioning device 100. The amount of refrigerant to be filled in the heat source unit 2 in advance also varies depending on the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8. However, in reality, it is not easy to grasp the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 to be constructed at the installation site of the air conditioning device 100 in advance before the installation work of the air conditioning device 100. Therefore, in the air conditioning device 100, which is a chargeless type refrigeration cycle device, the maximum length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 is assumed, and if the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 is within the maximum length, the predetermined amount (the amount of refrigerant to be filled in the heat source unit 2 in advance) is determined so that there is no shortage of refrigerant during operation of the air conditioning device 100. Therefore, if the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 is shorter than the expected maximum length, the refrigerant circuit 10 will contain a relatively large amount of excess refrigerant that is not essential for the operation of the air conditioning device 100.

A specific example of the installation of the chargeless type air conditioning device 100 of this embodiment will be described. The heat source unit 2 of the air conditioning device 100 is delivered to the installation site with all the refrigerants to be used in the air conditioning device 100 sealed in the heat source unit 2 in advance, and the first shutoff valve 28 and the second shutoff valve 29 closed. The utilization unit 4 of the air conditioning device 100 is delivered to the installation site without being connected to the heat source unit 2 by the connecting pipes 6 and 8. The heat source unit 2 and utilization unit 4 delivered to the installation site are each installed in a predetermined location. Thereafter, the heat source unit 2 and utilization unit 4 are connected by the liquid refrigerant connecting pipe 6 and the gas refrigerant connecting pipe 8. Then, after air is removed (vacuum drawing is performed) from the piping of the utilization unit 4, the inside of the second heat exchanger 41 described later, and the inside of the liquid refrigerant connecting pipe 6 and the gas refrigerant connecting pipe 8, the first shutoff valve 28 and the second shutoff valve 29 are opened. In the air conditioning device 100, additional refrigerant is not usually charged thereafter. Chargeless refrigeration cycle devices do not require additional refrigerant charging, which reduces the labor required for installation.

The air conditioning device 100 of this embodiment performs cooling operation and heating operation as normal operation according to the air conditioning load. Cooling operation is an operation in which the first heat exchanger 23 functions as a condenser and the second heat exchanger 41 functions as an evaporator to cool the air in the target space. Heating operation is an operation in which the first heat exchanger 23 functions as an evaporator and the second heat exchanger 41 functions as a condenser to warm the air in the target space.

(2) Detailed Configuration The utilization units 4, the heat source unit 2, the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8, and the control unit 50 of the air conditioning apparatus 100 will be described in detail.

(2-1) Usage Unit The usage unit 4 is installed in a space to be air-conditioned or in the ceiling space of the target space. In this embodiment, the usage unit 4 is a ceiling-embedded cassette type unit installed in the ceiling. However, the type of the usage unit 4 is not limited to the ceiling-embedded cassette type, and may be a ceiling-suspended type that is suspended from the ceiling, a wall-mounted type that is installed on a wall, a floor-standing type that is installed on the floor, a ceiling-embedded duct type in which the entire usage unit 4 is placed in the ceiling space, or the like.

As described above, the utilization unit 4 is connected to the heat source unit 2 via the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8, and together with the heat source unit 2, constitutes part of the refrigerant circuit 10.

The utilization unit 4 has a second heat exchanger 41 and a second fan 42 (see FIG. 1). The second heat exchanger 41 and the second fan 42 are housed in a casing (not shown). The utilization unit 4 has various sensors. In this embodiment, the sensors possessed by the utilization unit 4 include a fourth temperature sensor 44 and a target space temperature sensor 45 (see FIG. 1). The utilization unit 4 has a second control unit 43 that controls the operation of the utilization unit 4 (see FIG. 1).

The main configuration of the utilization unit 4 is further explained below.

(2-1-1) Second Heat Exchanger In the second heat exchanger 41, heat exchange is performed between the refrigerant flowing inside the second heat exchanger 41 and the medium passing through the second heat exchanger 41. In the present embodiment, in the second heat exchanger 41, heat exchange is performed between the refrigerant flowing inside the second heat exchanger 41 and the air in the target space for air conditioning.

The second heat exchanger 41 functions as an evaporator during cooling operation. The second heat exchanger 41 functions as a condenser during heating operation.

One end of the second heat exchanger 41 is connected to the liquid refrigerant connection pipe 6 via a refrigerant pipe. The other end of the second heat exchanger 41 is connected to the gas refrigerant connection pipe 8 via a refrigerant pipe. During cooling operation, refrigerant flows from the liquid refrigerant connection pipe 6 into the second heat exchanger 41, and the refrigerant flowing out of the second heat exchanger 41 flows into the gas refrigerant connection pipe 8. During heating operation, refrigerant flows from the gas refrigerant connection pipe 8 into the second heat exchanger 41, and the refrigerant flowing out of the second heat exchanger 41 flows into the liquid refrigerant connection pipe 6.

The second heat exchanger 41 is, for example, a fin-and-tube type heat exchanger having a heat transfer tube (not shown) and a number of fins (not shown), although the type is not limited thereto.

(2-1-2) Second Fan The second fan 42 draws air from the target space into the casing of the utilization unit 4 through an air inlet (not shown) of the casing, and supplies the air to the second heat exchanger 41. The air that has exchanged heat with the refrigerant in the second heat exchanger 41 is blown out from an air outlet (not shown) of the casing of the utilization unit 4 into the target space.

The second fan 42 is, for example, a turbofan. However, the type of the second fan 42 is not limited to a turbofan and may be selected as appropriate. The second fan 42 is a variable airflow fan driven by an inverter-controlled motor 42a.

(2-1-3) Sensors The utilization unit 4 has a fourth temperature sensor 44 and a target space temperature sensor 45 as sensors (see FIG. 1). The fourth temperature sensor 44 is an example of a sensor that measures the temperature or pressure of the refrigerant at a predetermined location in the refrigerant circuit 10. The utilization unit 4 may have a sensor other than the fourth temperature sensor 44 and the target space temperature sensor 45. Furthermore, instead of the fourth temperature sensor 44, the utilization unit 4 may have a sensor that measures a quantity that represents the state of the refrigerant at another location.

Although there is no limitation on the type of sensor, the fourth temperature sensor 44 and the target space temperature sensor 45 are, for example, thermistors.

The fourth temperature sensor 44 is provided in the second heat exchanger 41. The fourth temperature sensor 44 measures the temperature of the refrigerant flowing through the second heat exchanger 41.

The target space temperature sensor 45 is provided, for example, at the air intake port of the casing of the utilization unit 4. The target space temperature sensor 45 measures the temperature of the air in the target space that flows into the utilization unit 4.

(2-1-4) Second Control Unit The second control unit 43 controls the operation of each part that constitutes the utilization unit 4.

The second control unit 43 has a microcomputer provided to control the utilization unit 4. The microcomputer includes a CPU, memory including ROM and RAM, I/O, peripheral circuits, etc.

The second control unit 43 is electrically connected to the second fan 42, the fourth temperature sensor 44, and the target space temperature sensor 45 of the utilization unit 4 so as to be able to exchange control signals and information (including sensor measurement values) (see FIG. 1).

The second control unit 43 is also connected to the first control unit 30 of the heat source unit 2 in a state in which control signals and the like can be exchanged between the first control unit 30 and the second control unit 43.

The second control unit 43 is also configured to be able to receive various signals transmitted from a remote control 60 for operating the air conditioning device 100. The various signals transmitted from the remote control 60 include signals related to the operation/stop of the air conditioning device 100, signals related to the operation mode, and signals related to setting the target temperature for cooling operation and heating operation.

The second control unit 43 and the first control unit 30 of the heat source unit 2 work together to function as a control unit 50 that controls the operation of the air conditioning device 100. The function of the control unit 50 will be described later.

(2-2) Heat Source Unit The heat source unit 2 is installed, for example but not limited to, on the roof of the building in which the air conditioning device 100 is installed or in the periphery of the building.

As described above, the heat source unit 2 is connected to the utilization unit 4 via the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8, and together with the utilization unit 4, forms the refrigerant circuit 10.

The heat source unit 2 has a compressor 21, a flow path switching mechanism 22, a first heat exchanger 23, a first expansion valve 25, a second expansion valve 26, a receiver 24, a first shutoff valve 28, a second shutoff valve 29, and a first fan 27 (see FIG. 1). The compressor 21, the flow path switching mechanism 22, the first heat exchanger 23, the first expansion valve 25, the second expansion valve 26, the receiver 24, the first shutoff valve 28, the second shutoff valve 29, and the first fan 27 are housed in a casing (not shown) of the heat source unit 2. The heat source unit 2 has various sensors. In this embodiment, the sensors of the heat source unit 2 include an intake temperature sensor 31, a discharge temperature sensor 32, a first temperature sensor 33, a second temperature sensor 34, a third temperature sensor 35, and a heat source air temperature sensor 36 (see FIG. 1). The heat source unit 2 has a first control unit 30 that controls the operation of the heat source unit 2 (see Figure 1).

The heat source unit 2 has a suction pipe 37a, a discharge pipe 37b, a first gas refrigerant pipe 37c, a liquid refrigerant pipe 37d, and a second gas refrigerant pipe 37e (see Figure 1).

The suction pipe 37a connects the flow path switching mechanism 22 to the suction side of the compressor 21. The discharge pipe 37b connects the discharge side of the compressor 21 to the flow path switching mechanism 22. The first gas refrigerant pipe 37c connects the flow path switching mechanism 22 to the gas side of the first heat exchanger 23. The liquid refrigerant pipe 37d connects the liquid side of the first heat exchanger 23 to the first shutoff valve 28. The liquid refrigerant pipe 37d is provided with the first expansion valve 25, the second expansion valve 26, and the receiver 24. The second gas refrigerant pipe 37e connects the flow path switching mechanism 22 to the second shutoff valve 29.

The main configuration of the heat source unit 2 is further explained below.

(2-2-1) Compressor The compressor 21 is a device that draws in low-pressure refrigerant in a refrigeration cycle from a suction pipe 37a, compresses the refrigerant using a compression mechanism (not shown), and discharges the compressed refrigerant to a discharge pipe 37b.

The compressor 21 is a volumetric compressor, such as a rotary or scroll type, although the type is not limited thereto. The compression mechanism of the compressor 21, not shown, is driven by a motor 21a (see FIG. 1). The motor 21a is a variable speed motor that is inverter controlled. The capacity of the compressor 21 is controlled by controlling the rotation speed of the motor 21a.

(2-2-2) Flow path switching mechanism The flow path switching mechanism 22 is a mechanism that switches the flow direction of the refrigerant in the refrigerant circuit 10 between a first flow direction D1 and a second flow direction D2. When the flow direction of the refrigerant in the refrigerant circuit 10 is the first flow direction D1, the first heat exchanger 23 functions as a condenser, and the second heat exchanger 41 functions as an evaporator. When the flow direction of the refrigerant in the refrigerant circuit 10 is in the second flow direction D2, the first heat exchanger 23 functions as an evaporator, and the second heat exchanger 41 functions as a condenser.

During cooling operation, the flow path switching mechanism 22 switches the refrigerant flow direction to the first flow direction D1. For ease of explanation, the state of the refrigerant circuit 10 in which the refrigerant flow direction is switched to the first flow direction D1 is referred to as the first state. During heating operation, the flow path switching mechanism 22 switches the refrigerant flow direction to the second flow direction D2. For ease of explanation, the state of the refrigerant circuit 10 in which the refrigerant flow direction is switched to the second flow direction D2 is referred to as the second state.

The flow path switching mechanism 22 will now be described in more detail.

When the refrigerant circuit 10 is in the first state, the flow path switching mechanism 22 connects the suction pipe 37a to the second gas refrigerant pipe 37e and the discharge pipe 37b to the first gas refrigerant pipe 37c (see the solid lines in the flow path switching mechanism 22 in FIG. 1). When the flow direction of the refrigerant in the refrigerant circuit 10 is the first flow direction D1, the refrigerant discharged from the compressor 21 flows through the refrigerant circuit 10 in the order of the first heat exchanger 23 as a condenser, the first expansion valve 25, the second expansion valve 26, and the second heat exchanger 41 as an evaporator, and then returns to the compressor 21.

When the refrigerant circuit 10 is in the second state, the flow path switching mechanism 22 connects the suction pipe 37a to the first gas refrigerant pipe 37c and the discharge pipe 37b to the second gas refrigerant pipe 37e (see the dashed lines in the flow path switching mechanism 22 in FIG. 1). When the flow direction of the refrigerant in the refrigerant circuit 10 is the second flow direction D2, the refrigerant discharged from the compressor 21 flows through the refrigerant circuit 10 in the order of the second heat exchanger 41 as a condenser, the second expansion valve 26, the first expansion valve 25, and the first heat exchanger 23 as an evaporator, and then returns to the compressor 21.

In this embodiment, the flow path switching mechanism 22 is a four-way switching valve. However, the flow path switching mechanism 22 is not limited to a four-way switching valve. The flow path switching mechanism 22 may be configured, for example, to combine multiple solenoid valves and refrigerant pipes to achieve switching of the flow direction of the refrigerant.

(2-2-3) First Heat Exchanger In the first heat exchanger 23, heat exchange is performed between the refrigerant flowing inside the first heat exchanger 23 and a medium passing through the first heat exchanger 23. In the present embodiment, in the first heat exchanger 23, heat exchange is performed between the refrigerant flowing inside the first heat exchanger 23 and the air (heat source air) around the heat source unit 2.

The first heat exchanger 23 functions as a condenser during cooling operation. The first heat exchanger 23 functions as an evaporator during heating operation.

One end of the first heat exchanger 23 is connected to the liquid refrigerant pipe 37d. The other end of the first heat exchanger 23 is connected to the first gas refrigerant pipe 37c. During cooling operation, refrigerant flows into the first heat exchanger 23 from the first gas refrigerant pipe 37c, and the refrigerant flowing out of the first heat exchanger 23 flows into the liquid refrigerant pipe 37d. During heating operation, refrigerant flows into the first heat exchanger 23 from the liquid refrigerant pipe 37d, and the refrigerant flowing out of the first heat exchanger 23 flows into the first gas refrigerant pipe 37c.

The first heat exchanger 23 is, for example, a fin-and-tube type heat exchanger having a heat transfer tube (not shown) and a number of fins (not shown), although the type is not limited thereto.

(2-2-4) First Expansion Valve and Second Expansion Valve The first expansion valve 25 and the second expansion valve 26 are an example of an expansion mechanism. The first expansion valve 25 and the second expansion valve 26 are mechanisms that adjust the pressure and flow rate of the refrigerant flowing through the liquid refrigerant pipe 37d. The first expansion valve 25 and the second expansion valve 26 are, for example, electronic expansion valves with variable opening.

The first expansion valve 25 is disposed in the liquid refrigerant pipe 37d between the first heat exchanger 23 and the receiver 24. The second expansion valve 26 is disposed in the liquid refrigerant pipe 37d between the receiver 24 and the first shutoff valve 28.

During cooling operation, the first expansion valve 25 is disposed between the condenser and the receiver 24, and the second expansion valve 26 is disposed between the receiver 24 and the evaporator. During heating operation, the second expansion valve 26 is disposed between the condenser and the receiver 24, and the first expansion valve 25 is disposed between the receiver 24 and the evaporator.

(2-2-5) Receiver The receiver 24 is a container capable of storing the refrigerant.

The receiver 24 is disposed between the first heat exchanger 23 and the second heat exchanger 41 in the refrigerant circuit 10. In other words, the receiver 24 is disposed between the condenser and the evaporator in the refrigerant circuit 10. The receiver 24 is disposed between the first expansion valve 25 and the second expansion valve 26 in the liquid refrigerant pipe 37d.

(2-2-6) First shut-off valve and second shut-off valve The first shut-off valve 28 is a valve provided at the connection between the liquid refrigerant pipe 37d and the liquid refrigerant communication pipe 6. The second shut-off valve 29 is a valve provided at the connection between the second gas refrigerant pipe 37e and the gas refrigerant communication pipe 8. The first shut-off valve 28 and the second shut-off valve 29 are, for example, valves that are operated manually. When the air conditioning apparatus 100 is in operation, the first shut-off valve 28 and the second shut-off valve 29 are open.

(2-2-7) First Fan The first fan 27 draws heat source air from outside the heat source unit 2 into the casing through an air inlet (not shown) of the casing of the heat source unit 2, and supplies the air to the first heat exchanger 23. The air that has exchanged heat with the refrigerant in the first heat exchanger 23 is blown out from an air outlet (not shown) of the casing of the heat source unit 2, not shown.

The first fan 27 is, for example, a propeller fan. However, the type of the first fan 27 is not limited to a propeller fan and may be selected as appropriate. The first fan 27 is a variable airflow fan driven by an inverter-controlled motor 27a.

(2-2-8) Sensors The heat source unit 2 has the following sensors: an intake temperature sensor 31, a discharge temperature sensor 32, a first temperature sensor 33, a second temperature sensor 34, a third temperature sensor 35, and a heat source air temperature sensor 36 (see FIG. 1). The intake temperature sensor 31, the discharge temperature sensor 32, the first temperature sensor 33, the second temperature sensor 34, and the third temperature sensor 35 are examples of sensors that measure the temperature or pressure of the refrigerant at a predetermined location in the refrigerant circuit 10. The heat source unit 2 may have sensors other than the intake temperature sensor 31, the discharge temperature sensor 32, the first temperature sensor 33, the second temperature sensor 34, the third temperature sensor 35, and the heat source air temperature sensor 36. The heat source unit 2 may also have only some of the sensors, the intake temperature sensor 31, the discharge temperature sensor 32, the first temperature sensor 33, the second temperature sensor 34, the third temperature sensor 35, and the heat source air temperature sensor 36.

Although there is no limitation on the type of the sensors, the intake temperature sensor 31, the discharge temperature sensor 32, the first temperature sensor 33, the second temperature sensor 34, the third temperature sensor 35, and the heat source air temperature sensor 36 are, for example, thermistors.

The suction temperature sensor 31 is provided in the suction pipe 37a. The suction temperature sensor 31 measures the temperature (suction temperature) of the refrigerant suctioned into the compressor 21.

The discharge temperature sensor 32 is provided in the discharge pipe 37b. The discharge temperature sensor 32 measures the temperature (discharge temperature) of the refrigerant discharged by the compressor 21.

The first temperature sensor 33 is provided in the first heat exchanger 23. The first temperature sensor 33 measures the temperature of the refrigerant flowing through the first heat exchanger 23.

The second temperature sensor 34 is provided between the first heat exchanger 23 and the first expansion valve 25. The second temperature sensor 34 measures the temperature of the refrigerant flowing between the first heat exchanger 23 and the first expansion valve 25.

The third temperature sensor 35 is provided between the second expansion valve 26 and the second heat exchanger 41. The third temperature sensor 35 measures the temperature of the refrigerant flowing between the second expansion valve 26 and the second heat exchanger 41.

The heat source air temperature sensor 36 measures the temperature of the heat source air that exchanges heat with the refrigerant in the first heat exchanger 23.

(2-2-9) First Control Unit The first control unit 30 controls the operation of each part that constitutes the heat source unit 2.

The first control unit 30 has a microcomputer provided to control the heat source unit 2. The microcomputer includes a CPU, memory including ROM and RAM, I/O, peripheral circuits, etc.

The first control unit 30 is electrically connected to the compressor 21, flow path switching mechanism 22, first expansion valve 25, second expansion valve 26, first fan 27, intake temperature sensor 31, discharge temperature sensor 32, first temperature sensor 33, second temperature sensor 34, third temperature sensor 35, and heat source air temperature sensor 36 of the heat source unit 2 so as to be able to exchange control signals and information (including sensor measurement values) (see Figure 1).

The first control unit 30 is also connected to the second control unit 43 of the utilization unit 4 in a state in which control signals and the like can be exchanged between the first control unit 30 and the second control unit 43.

The first control unit 30 and the second control unit 43 of the utilization unit 4 work together to function as a control unit 50 that controls the operation of the air conditioning device 100. The function of the control unit 50 will be described later.

(2-3) Refrigerant communication pipe The air conditioning apparatus 100 has, as examples of communication pipes, a liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 8. Hereinafter, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 8 may be collectively referred to as the communication pipes 6, 8.

The liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 are pipes that are installed at the installation site of the air conditioning unit 100 when the air conditioning unit 100 is installed. The lengths of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 are determined according to the installation conditions (the distance between the installation sites of the heat source unit 2 and the utilization unit 4, the piping route, etc.).

(2-4) Control Unit The control unit 50 is configured by communicatively connecting the first control unit 30 of the heat source unit 2 and the second control unit 43 of the utilization unit 4. The control unit 50 controls the operation of the entire air conditioning apparatus 100 by the CPU of the microcomputer of the first control unit 30 or the second control unit 43 executing a program stored in the memory.

Note that the control unit 50 of this embodiment is merely an example. The control unit may realize functions similar to those performed by the control unit 50 of this embodiment using hardware such as a logic circuit, or may realize the functions using a combination of hardware and software.

In addition, here, the first control unit 30 and the second control unit 43 constitute the control unit 50, but this is not limited to this. For example, in addition to the first control unit 30 and the second control unit 43, or instead of the first control unit 30 and the second control unit 43, the air conditioning device 100 may have a control device provided separately from the heat source unit 2 and the utilization unit 4 that realizes some or all of the functions of the control unit 50 described below. Also, some or all of the functions of the control unit 50 described below may be realized by a server or the like installed in a location separate from the air conditioning device 100.

2, the control unit 50 is electrically connected to various devices of the heat source unit 2 and the utilization unit 4, including the compressor 21, the flow path switching mechanism 22, the first expansion valve 25, the second expansion valve 26, the first fan 27, and the second fan 42. Also, as shown in FIG. 2, the control unit 50 is electrically connected to the intake temperature sensor 31, the discharge temperature sensor 32, the first temperature sensor 33, the second temperature sensor 34, the third temperature sensor 35, the fourth temperature sensor 44, the heat source air temperature sensor 36, and the target space temperature sensor 45.

The control unit 50 is connected to the monitoring device 200 so as to be able to communicate with it via the communication unit 56 and a network NW such as the Internet. The communication unit 56 is, for example, a communication control device possessed by the first control unit 30 or the second control unit 43. Although not shown here, the monitoring device 200 may be connected to multiple refrigeration cycle devices in addition to the air conditioning device 100. The monitoring device 200 monitors the state of the refrigeration cycle devices including the air conditioning device 100, and accumulates various information transmitted from the refrigeration cycle devices. For example, the control unit 50 transmits the result of the refrigerant leakage judgment of the control unit 52 described later to the monitoring device 200, and the monitoring device 200 stores the acquired result of the refrigerant leakage judgment as the result of the refrigerant leakage judgment of the air conditioning device 100. The administrator of the air conditioning device 100 who uses the monitoring device 200 can know whether or not refrigerant is leaking from the refrigerant circuit 10 of the air conditioning device 100 based on the result of the refrigerant leakage judgment transmitted by the control unit 50.

The control unit 50 is also communicatively connected to a mobile terminal 300 via a communication unit 56 and a network NW such as the Internet. The mobile terminal 300 is a device used by an operator to input various commands and information to the control unit 50, for example, during installation of the air conditioning device 100. The mobile terminal 300 is, for example, a smartphone or a tablet computer. Note that the control unit 50 and the mobile terminal 300 may be configured to be connectable by a communication cable rather than via the network NW.

The control unit 50 functions as a control unit 52 having the functions described below by the CPU of the microcomputer of the first control unit 30 or the second control unit 43 executing a program stored in the memory. The control unit 50 also has a memory unit 54 that stores various information.

The control unit 52 has the following functions, for example:

<Control of Air Conditioner Operation>
When the air-conditioning apparatus 100 performs cooling operation and heating operation, the control unit 52 controls the operation of each part of the heat source unit 2 and the utilization unit 4. How the control unit 52 controls the air-conditioning apparatus 100 during cooling operation and heating operation will be described later.

<Receiving instructions and information>
The control unit 52 receives various commands and information transmitted from the mobile terminal 300 and acquired by a remote control 60 or a communication unit 56 (an example of an acquisition unit).

The information acquired by the communication unit 56 and received by the control unit 52 includes information regarding the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8. Hereinafter, for the sake of simplicity, the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 may be referred to as the connection pipe length. Also, for the sake of simplicity, the information regarding the length of the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 8 received by the control unit 52 may be referred to as connection pipe length information.

The communication pipe length information is, for example, the length value of the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 8. The communication pipe length information may also be, for example, a code indicating the length range (e.g., 10 to 15 m) to which the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 8 belong. The communication pipe length information received by the control unit 52 is stored in the memory unit 54.

The communication pipe length information is transmitted from the mobile terminal 300 to the communication unit 56, for example, when the control unit 52 and the monitoring device 200 are communicatively connected via the communication unit 56. In other words, the communication unit 56, which is an example of an acquisition unit, acquires the communication pipe length information when the control unit 52 and the monitoring device 200 are communicatively connected via the communication unit 56. Note that the time when the control unit 52 and the monitoring device 200 are communicatively connected does not mean the same time as the control unit 52 and the monitoring device 200 are communicatively connected, but includes a predetermined period before and after the connection work between the control unit 52 and the monitoring device 200 is performed.

When the control unit 52 and the monitoring device 200 are communicatively connected, if the communication pipe length information is not stored in the memory unit 54, the control unit 52 may transmit image information prompting the mobile terminal 300 to input via the communication unit 56 so that information prompting the input is displayed on the mobile terminal 300 as an output device. Furthermore, the control unit 52 may be configured to prohibit operation of the air conditioning device 100 if the communication pipe length information is not stored in the memory unit 54.

Note that here, the control unit 52 receives the communication pipe length information from the mobile terminal 300, but is not limited to this. For example, if the remote control 60 has a function for receiving input of communication pipe length information, the control unit 52 may receive communication pipe length information acquired by the remote control 60, which is another example of an acquisition unit. For example, the communication pipe length information is input to the remote control 60 when the air conditioning device 100 is installed. In this case, when the control unit 52 and the monitoring device 200 are connected to be able to communicate with each other, if the communication pipe length information is not stored in the memory unit 54, the control unit 52 may transmit image information prompting the remote control 60 to input information so that information prompting the input is displayed on the display unit of the remote control 60.

<Detection of superheat and subcooling degrees>
The control unit 52 detects the discharge superheat degree of the refrigerant in the compressor 21 (hereinafter may be simply referred to as the discharge superheat degree), the superheat degree of the refrigerant at the outlet of the evaporator (hereinafter may be simply referred to as the suction superheat degree), and the subcooling degree of the refrigerant at the outlet of the condenser (hereinafter may be simply referred to as the subcooling degree) based on the measurement results of the sensors in the air-conditioning device 100. Here, the term "detecting a value" not only means obtaining the measurement result of a single sensor as a value, but also includes the meaning of calculating a value based on the measurement results of multiple sensors.

The control unit 52 does not need to detect all of the discharge superheat degree, the intake superheat degree, and the subcooling degree, and does not need to detect values that are not used for controlling the equipment or determining conditions. For example, the control unit 52 may detect either the discharge superheat degree or the intake superheat degree, and the subcooling degree.

When the first heat exchanger 23 functions as a condenser, the control unit 52 detects (calculates) the degree of discharge superheat, for example, by subtracting the measurement value of the first temperature sensor 33 from the measurement value of the discharge temperature sensor 32. Also, when the first heat exchanger 23 functions as a condenser, the control unit 52 detects (calculates) the degree of intake superheat, for example, by subtracting the measurement value of the fourth temperature sensor 44 from the measurement value of the intake temperature sensor 31. Also, when the first heat exchanger 23 functions as a condenser, the control unit 52 detects (calculates) the degree of subcooling, for example, by subtracting the measurement value of the second temperature sensor 34 from the measurement value of the first temperature sensor 33.

When the second heat exchanger 41 functions as a condenser, the control unit 52 detects (calculates) the degree of discharge superheat, for example, by subtracting the measurement value of the fourth temperature sensor 44 from the measurement value of the discharge temperature sensor 32. Also, when the second heat exchanger 41 functions as a condenser, the control unit 52 detects (calculates) the degree of intake superheat, for example, by subtracting the measurement value of the first temperature sensor 33 from the measurement value of the intake temperature sensor 31. Also, when the second heat exchanger 41 functions as a condenser, the control unit 52 detects (calculates) the degree of subcooling, for example, by subtracting the measurement value of the third temperature sensor 35 from the measurement value of the fourth temperature sensor 44.

The method of detecting the discharge superheat, intake superheat, and subcooling described here is merely an example. For example, the refrigerant circuit 10 may be provided with temperature sensors and pressure sensors other than those illustrated, and the control unit 52 may detect the discharge superheat, intake superheat, or subcooling based on the measurement results of these sensors.

<Determining whether a refrigerant leak has occurred>
The control unit 52 determines whether or not there is a refrigerant leak from the refrigerant circuit 10 based on the measurement values of the various sensors.

The control unit 52 determines whether or not there is a refrigerant leak from the refrigerant circuit 10, for example, at a predetermined timing. As a specific example, the control unit 52 determines whether or not there is a refrigerant leak from the refrigerant circuit 10, for example, once a day at a predetermined time. The control unit 52 may also determine whether or not there is a refrigerant leak from the refrigerant circuit 10 when, for example, an instruction to determine whether or not there is a refrigerant leak is input to the remote control 60 or the like.

In the present disclosure, the control unit 52 can execute a first mode in which the presence or absence of refrigerant leakage from the refrigerant circuit 10 is determined by a first method, and a second mode in which the presence or absence of refrigerant leakage from the refrigerant circuit 10 is determined by a second method. The control unit 52 executes the first mode or the second mode at a predetermined timing to determine the presence or absence of refrigerant leakage. How the control unit 52 uses the first mode and the second mode will be described later. The details of the first method and the second method will also be described later.

(3) Operation of the Air Conditioner The operation of the air conditioner 100 during cooling operation and heating operation will be described.

(3-1) Cooling Operation The cooling operation performed by the control unit 52 will be described.

When performing cooling operation, the control unit 52 puts the refrigerant circuit 10 into the first state and starts the compressor 21, the first fan 27, and the second fan 42. As a result of putting the refrigerant circuit 10 into the first state and operating the compressor 21, refrigerant circulates in the refrigerant circuit 10 as follows.

The low-pressure gas refrigerant in the refrigerant circuit 10 is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. The high-pressure gas refrigerant discharged from the compressor 21 is sent to the first heat exchanger 23 functioning as a condenser. The high-pressure gas refrigerant that flows into the first heat exchanger 23 is cooled and condensed by heat exchange with the heat source air supplied by the first fan 27 in the first heat exchanger 23, becoming a high-pressure liquid refrigerant. This high-pressure liquid refrigerant is sent to the first expansion valve 25 and depressurized in the first expansion valve 25. The refrigerant depressurized in the first expansion valve 25 is temporarily stored in the receiver 24, then sent to the second expansion valve 26 and depressurized in the second expansion valve 26. The refrigerant depressurized in the second expansion valve 26 is sent to the utilization unit 4 via the liquid refrigerant connection pipe 6. The refrigerant sent to the utilization unit 4 is sent to the second heat exchanger 41 functioning as an evaporator. The low-pressure refrigerant that flows into the second heat exchanger 41 exchanges heat with the air in the target space supplied by the second fan 42, is heated and evaporated, and becomes a low-pressure gas refrigerant. At this time, the air that has been cooled by heat exchange with the refrigerant in the second heat exchanger 41 is blown out into the target space from the air outlet of the casing (not shown) of the utilization unit 4. The low-pressure gas refrigerant that has evaporated in the second heat exchanger 41 is sucked into the compressor 21 via the gas refrigerant connection pipe 8, the second gas refrigerant pipe 37e, and the suction pipe 37a.

Although not limited thereto, during cooling operation, the control unit 52 controls the compressor 21, the first expansion valve 25, and the second expansion valve 26 as follows:

The control unit 52 controls the opening of the first expansion valve 25 so that the degree of subcooling is adjusted to a predetermined first target value. The degree of subcooling is calculated, for example, by subtracting the measurement value of the second temperature sensor 34 from the measurement value of the first temperature sensor 33. The control unit 52 also controls the rotation speed of the compressor 21 so that the evaporation temperature in the second heat exchanger 41 (measurement value of the fourth temperature sensor 44) is adjusted to the target evaporation temperature. The target evaporation temperature is determined based on the temperature difference between the temperature of the target space measured by the target space temperature sensor 45 and the set temperature for cooling operation. The control unit 52 also controls the opening of the second expansion valve 26 so that the dryness of the refrigerant sucked into the compressor 21 is adjusted to a predetermined target value.

(3-2) Heating Operation A description will now be given of the heating operation executed by the control unit 52. The heating operation is an example of a normal operation according to the air conditioning load.

When performing heating operation, the control unit 52 puts the refrigerant circuit 10 into the second state and starts the compressor 21, the first fan 27, and the second fan 42. As a result of putting the refrigerant circuit 10 into the second state and operating the compressor 21, refrigerant circulates in the refrigerant circuit 10 as follows.

The low-pressure gas refrigerant in the refrigerant circuit 10 is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. The high-pressure gas refrigerant discharged from the compressor 21 is sent to the second heat exchanger 41, which functions as a condenser. The high-pressure gas refrigerant that flows into the second heat exchanger 41 is cooled and condensed by heat exchange with the air in the target space supplied by the second fan 42 in the second heat exchanger 41, and becomes a high-pressure liquid refrigerant. At this time, the air heated by heat exchange with the refrigerant in the second heat exchanger 41 is blown out into the target space from the air outlet of the casing (not shown) of the utilization unit 4. The high-pressure liquid refrigerant flowing out from the second heat exchanger 41 is sent to the heat source unit 2 via the liquid refrigerant connection pipe 6. The refrigerant that flows into the heat source unit 2 is sent to the second expansion valve 26 and depressurized in the second expansion valve 26. The refrigerant depressurized in the second expansion valve 26 is temporarily stored in the receiver 24, then sent to the first expansion valve 25 and depressurized in the first expansion valve 25. The refrigerant decompressed in the first expansion valve 25 is sent to the first heat exchanger 23, which functions as an evaporator. The low-pressure refrigerant that flows into the first heat exchanger 23 exchanges heat with the heat source air supplied by the first fan 27 in the first heat exchanger 23, where it is heated and evaporated, becoming a low-pressure gas refrigerant. The low-pressure gas refrigerant evaporated in the first heat exchanger 23 is sucked into the compressor 21 via the first gas refrigerant pipe 37c and the suction pipe 37a.

Although not limited thereto, during heating operation, the control unit 52 controls the compressor 21, the first expansion valve 25, and the second expansion valve 26 as follows:

The control unit 52 controls the opening of the second expansion valve 26 so that the degree of subcooling is adjusted to a predetermined second target value. The degree of subcooling is calculated, for example, by subtracting the measurement value of the third temperature sensor 35 from the measurement value of the fourth temperature sensor 44. The control unit 52 also controls the rotation speed of the compressor 21 so that the condensing temperature in the second heat exchanger 41 (measurement value of the fourth temperature sensor 44) is adjusted to the target condensing temperature. The target condensing temperature is determined based on the temperature difference between the temperature of the target space measured by the target space temperature sensor 45 and the set temperature for heating operation. The control unit 52 also controls the opening of the first expansion valve 25 so that the dryness of the refrigerant sucked into the compressor 21 is adjusted to a predetermined target value.

(4) Determination of refrigerant leakage (4-1) Method of determining refrigerant leakage in first mode and second mode The following describes a method of determining refrigerant leakage in the first mode (first method) executed by the control unit 52, and a method of determining refrigerant leakage in the second mode (second method) executed by the control unit 52. Note that the method of determining refrigerant leakage described below is merely one embodiment, and can be modified as appropriate within the scope of the gist of the determination method.

(a) First Method The first method for determining whether or not a refrigerant leak has occurred will be described with reference to the flowchart of Fig. 3. Fig. 3 is a flowchart of the process executed by the control unit 52 when the control unit 52 determines whether or not a refrigerant leak has occurred using the first method.

Here, a description will be given of a mode in which the control unit 52 determines the presence or absence of a refrigerant leak using the first method based on the measurement value detected by the sensor during cooling operation. However, this is not limited to this, and the control unit 52 may also determine the presence or absence of a refrigerant leak using the first method based on the measurement value detected by the sensor during heating operation.

When determining whether a refrigerant leaks using the first method, the control unit 52 sets the third target value to an initial value (initial target value) (step S1). The third target value is the target value of the degree of subcooling when the air conditioning device 100 performs cooling operation from step S2 onwards, which will be described below. The initial value may be the first target value (the target value of the degree of subcooling during normal cooling operation), or may be a value different from the first target value (for example, a value greater than the first target value).

Next, the control unit 52 controls the operation of each part of the air conditioning device 100 so that the air conditioning device 100 performs cooling operation (step S2). At this time, the control unit 52 controls the opening degree of the first expansion valve 25 so that the degree of subcooling at the outlet of the condenser (here, the first heat exchanger 23) becomes the third target value.

After a predetermined time has elapsed since the start of cooling operation, the control unit 52 detects (calculates) the degree of subcooling and determines whether the degree of subcooling is equal to or greater than the third target value (step S3).

If it is determined in step S3 that the degree of subcooling is equal to or greater than the third target value, the process proceeds to step S10, where the control unit 52 determines that there is no refrigerant leakage. The control unit 52 may notify the monitoring device 200 via the communication unit 56 that there is no refrigerant leakage.

On the other hand, if it is determined in step S3 that the degree of subcooling is less than the third target value, the process proceeds to step S4, where the control unit 52 controls the opening of the first expansion valve 25 to be reduced by a predetermined amount.

Then, after a predetermined time has elapsed since adjusting the opening degree of the first expansion valve 25, the control unit 52 again determines whether the degree of subcooling is equal to or greater than the third target value (step S5).

If the determination in step S5 indicates that the degree of subcooling is equal to or greater than the third target value, the process proceeds to step S10, and the control unit 52 determines that there is no refrigerant leakage. The control unit 52 may notify the monitoring device 200 via the communication unit 56 that there is no refrigerant leakage.

On the other hand, if the determination in step S5 indicates that the degree of superheat is less than the third target value, the process proceeds to step S6. In step S6, the control unit 52 determines whether the first degree of superheat is equal to or greater than the first value. The first degree of superheat is the discharge superheat or the suction superheat. The first value is set to an appropriate value depending on whether the first degree of superheat is the discharge superheat or the suction superheat. The first value is, for example, a value suitable for suppressing overheating of the compressor 21.

If the first degree of superheat is less than the threshold in the determination in step S6, the process returns to step S4. On the other hand, if the first degree of superheat is greater than or equal to the threshold in the determination in step S6, the process proceeds to step S7.

In another example, in step S6, it may be determined whether the discharge superheat degree is equal to or greater than the first value for the discharge superheat degree, and whether the intake superheat degree is equal to or greater than the first value for the intake superheat degree. If neither of these is true, the process may return to step S4, and if either or both are true, the process may proceed to step S7.

In step S7, the control unit 52 sets the new third target value to a value obtained by subtracting the predetermined value α from the third target value. Although not limited thereto, the predetermined value α is, for example, 1°C.

When the third target value is updated in step S7, the process proceeds to step S8. In step S8, the control unit 52 determines whether the third target value updated in step S7 is lower than the initial value set for the third target value in step S1 by a second value (e.g., 5°C) or more. Note that here, the control unit 52 determines whether the third target value is lower than the initial value by a second value or more, but instead, the control unit 52 may determine whether the correction amount from the initial value of the third target value (current third target value - initial value) has fallen below a predetermined value.

If it is determined in step S8 that the third target value is lower than the initial value by the second value or more, the process proceeds to step S9, where the control unit 52 determines that there is a refrigerant leak. The control unit 52 then notifies the monitoring device 200 that there is a refrigerant leak.

If it is determined in step S8 that the third target value is greater than the initial value minus the second value, the process returns to step S5. In this case, the third target value updated in step S7 is used in the process of step S5.

When it is determined in step S9 that there is a refrigerant leak, the control unit 52 does not have to immediately notify the monitoring device 200 that there is a refrigerant leak. For example, the control unit 52 may determine the presence or absence of a refrigerant leak using the first method described above multiple times (e.g., three times), and if it is determined that there is a refrigerant leak every time, may notify the monitoring device 200 that there is a refrigerant leak.

(b) Second Method The second method for determining whether or not a refrigerant leak has occurred will be described with reference to the flowchart of Fig. 4. Fig. 4 is a flowchart of the process executed by the control unit 52 when the control unit 52 determines whether or not a refrigerant leak has occurred using the second method.

Here, a description will be given of a mode in which the control unit 52 determines the presence or absence of a refrigerant leak using the second method based on the measurement value detected by the sensor during cooling operation. However, this is not limited to this, and the control unit 52 may also determine the presence or absence of a refrigerant leak using the second method based on the measurement value detected by the sensor during heating operation.

When determining whether or not there is a refrigerant leak using the second method, the control unit 52 acquires the measurement value (hereinafter referred to as the initial condenser temperature) of the sensor attached to the condenser before the air conditioning device 100 is operated (step S11). Specifically, the control unit 52 acquires the measurement value of the first temperature sensor 33.

Next, the control unit 52 controls the operation of each part of the air conditioning device 100 so that the air conditioning device 100 performs cooling operation (step S12).

When determining whether or not there is a refrigerant leak using the second method, the control unit 52 operates the motor 21a of the compressor 21 at a predetermined rotation speed or higher during cooling operation. For example, the control unit 52 determines whether or not there is a refrigerant leak using the second method only when the temperature of the target space for air conditioning is higher than the set temperature (target temperature of the target space) by a predetermined value or more at the start of cooling operation, so that this condition is satisfied.

Next, the control unit 52 determines whether a predetermined time has elapsed since the air conditioning device 100 started cooling operation (step S13). If it is determined that the predetermined time has elapsed, the process proceeds to step S14.

In step S14, the control unit 52 acquires the condensation temperature. Specifically, the control unit 52 acquires the measurement value of the first temperature sensor 33 as the condensation temperature.

Next, in step S15, the control unit 52 acquires the air temperature around the condenser. Specifically, the control unit 52 acquires the measurement value of the heat source air temperature sensor 36.

Next, in step S16, the control unit 52 determines whether the value obtained by subtracting the initial condenser temperature from the condensation temperature acquired in step S14 is equal to or greater than β°C (β>0). In other words, in step S16, the control unit 52 determines whether the condensation temperature (condenser temperature) has increased by a predetermined temperature or more since step S11.

If it is determined in step S16 that the value obtained by subtracting the initial condenser temperature from the condensing temperature obtained in step S14 is equal to or greater than β°C, the process proceeds to step S17. On the other hand, if it is determined in step S16 that the value obtained by subtracting the initial condenser temperature from the condensing temperature obtained in step S14 is less than β°C, the control unit 52 determines that there is a refrigerant leak (step S19). The control unit 52 then notifies the monitoring device 200 that there is a refrigerant leak.

In step S17, the control unit 52 determines whether the value obtained by subtracting the air temperature obtained in step S14 from the condensation temperature obtained in step S14 is equal to or higher than γ°C (γ>0). In other words, in step S17, the control unit 52 determines whether the condensation temperature is higher than the air temperature around the condenser by a predetermined temperature or more.

If it is determined in step S17 that the value obtained by subtracting the air temperature obtained in step S14 from the condensation temperature obtained in step S14 is equal to or greater than γ°C, the control unit 52 determines that there is no refrigerant leakage (step S18). The control unit 52 may notify the monitoring device 200 that there is no refrigerant leakage.

If it is determined in step S17 that the value obtained by subtracting the air temperature obtained in step S14 from the condensation temperature obtained in step S14 is less than γ°C, the control unit 52 determines that there is a refrigerant leak (step S19). Then, the control unit 52 notifies the monitoring device 200 that there is a refrigerant leak.

When it is determined in step S19 that there is a refrigerant leak, the control unit 52 does not have to immediately notify the monitoring device 200 that there is a refrigerant leak. For example, the control unit 52 may determine whether there is a refrigerant leak using the second method described above multiple times (e.g., three times), and when it is determined that there is a refrigerant leak every time, may notify the monitoring device 200 that there is a refrigerant leak.

In addition, in the flowchart of FIG. 4, the presence or absence of a refrigerant leak is determined based on whether the temperature of the condenser has risen by a predetermined temperature or more since before the air conditioner started operating, and whether the condensation temperature is higher by a predetermined temperature or more than the air surrounding the condenser. However, this is not limited to this, and the control unit 52 may also determine the presence or absence of a refrigerant leak based on whether the temperature of the evaporator has dropped by a predetermined temperature or more since before the air conditioner started operating, and whether the evaporation temperature is lower by a predetermined temperature or more than the air surrounding the evaporator. A detailed explanation is omitted.

In addition, when using the second method, the air temperature around the condenser before the air conditioning device starts operating may be compared with the air temperature around the condenser when the refrigerant leak is judged, and if the difference is greater than a predetermined value, the refrigerant leak judgment may be stopped because the change in air temperature may adversely affect the refrigerant leak judgment.

(4-2) Proper Use of the First Mode and the Second Mode The following describes how the control unit 52 determines whether to execute the first mode or the second mode to determine the presence or absence of a refrigerant leak, with reference to a flowchart. Fig. 5 is a flowchart of the process executed by the control unit 52 to determine the mode for determining the presence or absence of a refrigerant leak.

As described above, for example, when the control unit 52 and the monitoring device 200 are connected so as to be able to communicate with each other, the control unit 52 receives the communication pipe length information (step S21). Alternatively, in another example, when the air conditioning device 100 is installed, the communication pipe length information is input to the remote control 60, and the control unit 52 receives the communication pipe length information input to the remote control 60.

Then, the control unit 52 determines whether the communication pipe length determined from the communication pipe length information is shorter than a threshold value (step S22). If the communication pipe length is shorter than the threshold value, the control unit 52 decides to execute the first mode to determine whether or not there is a refrigerant leak (step S23). On the other hand, if the communication pipe length is equal to or greater than the threshold value, the control unit 52 decides to execute the second mode to determine whether or not there is a refrigerant leak (step S24).

The reasons for using the first and second modes in this way are as follows:

The second method described above is, in essence, a method for determining whether or not there is a refrigerant leak based on whether the air conditioning device 100 can perform at its full potential. If the amount of excess refrigerant in the original refrigerant circuit 10 is relatively large, the performance of the air conditioning device 100 is unlikely to deteriorate even if a small amount of refrigerant leaks. Therefore, if the amount of excess refrigerant in the original refrigerant circuit 10 is relatively large, it is difficult to detect a small amount of refrigerant leakage when using the second method.

On the other hand, the first method described above is capable of detecting a smaller amount of refrigerant leakage than the second method. Therefore, when the first method is used, it is easy to detect a refrigerant leakage even when the amount of excess refrigerant in the original refrigerant circuit 10 is relatively large and the amount of refrigerant leakage is relatively small.

However, because the first method is capable of detecting smaller amounts of refrigerant leakage than the second method, if the amount of excess refrigerant in the original refrigerant circuit 10 is relatively small, there is a risk that a state in which there is no refrigerant leakage will be mistakenly determined to be a refrigerant leakage.

Here, when the length of the interconnecting pipe is shorter than the threshold and there is a relatively large amount of excess refrigerant, the control unit 52 executes the first mode to determine whether or not there is a refrigerant leak. On the other hand, when the length of the interconnecting pipe is shorter than the threshold and there is a relatively small amount of excess refrigerant, the control unit 52 executes the second mode to determine whether or not there is a refrigerant leak.

(5) Features (5-1)
The air-conditioning apparatus 100 includes a refrigerant circuit 10, sensors 31-35, 44, and a control unit 52. The refrigerant circuit 10 includes communication pipes 6, 8 (liquid refrigerant communication pipe 6 and gas refrigerant communication pipe 8) that connect the heat source unit 2 and the utilization unit 4. The sensors 31-35, 44 measure the temperature or pressure of the refrigerant at a predetermined location in the refrigerant circuit 10. The control unit 52 determines whether or not there is refrigerant leakage from the refrigerant circuit 10 based on the measured values of the sensors 31-35, 44. When the length of the communication pipes 6, 8 satisfies a predetermined condition, the control unit 52 executes a first mode in which the presence or absence of refrigerant leakage from the refrigerant circuit 10 is determined by a first method. When the length of the communication pipes 6, 8 does not satisfy a predetermined condition, the control unit 52 executes a second mode in which the presence or absence of refrigerant leakage from the refrigerant circuit 10 is determined by a second method different from the first method.

In the air conditioning device 100, by using different detection methods depending on the length of the interconnecting pipes 6, 8, refrigerant leakage can be detected with high accuracy regardless of the length of the interconnecting pipes 6, 8.

(5-2)
In the air conditioning apparatus 100, the predetermined condition used to determine whether to execute the first mode or the second mode is that the length of the communication pipes 6, 8 is shorter than a threshold value.

In the air conditioning device 100, the detection method used is changed depending on whether the length of the connecting pipes 6, 8 is short or long, so that refrigerant leakage can be detected with high accuracy regardless of the length of the connecting pipes 6, 8.

(5-3)
In the air conditioning device 100, the sensors 31 to 35 and 44 include an intake temperature sensor 31, a discharge temperature sensor 32, a first temperature sensor 33, a second temperature sensor 34, a third temperature sensor 35, and a fourth temperature sensor 44.

In the first mode, the control unit 52 determines whether or not there is a refrigerant leak from the refrigerant circuit 10 based on the measurement value of the first sensor. In the second mode, the control unit 52 determines whether or not there is a refrigerant leak from the refrigerant circuit 10 based on the measurement value of a second sensor different from the first sensor. Note that the first sensor used in the first mode and the second sensor used in the second mode being different here also includes a case where the combination of sensors used in the first mode is different from the combination of sensors used in the second mode.

For example, in the above embodiment, in the first mode, the control unit 52 determines whether or not there is refrigerant leakage from the refrigerant circuit 10 based on the measurement value of the first temperature sensor 33 and the measurement value of the second temperature sensor 34, as well as the measurement value of the discharge temperature sensor 32, or the measurement value of the suction temperature sensor 31 and the measurement value of the fourth temperature sensor 44. In the second mode, the control unit 52 determines whether or not there is refrigerant leakage from the refrigerant circuit 10 based on the measurement value of the first temperature sensor 33.

In the air conditioning device 100, refrigerant leakage is detected based on the measurement values of sensors that differ depending on the length of the interconnecting pipes 6 and 8, so that refrigerant leakage can be detected with high accuracy regardless of the length of the interconnecting pipes 6 and 8.

(5-4)
In the air conditioning apparatus 100, the first method is capable of detecting a smaller amount of refrigerant leakage than the second method.

In the air conditioning device 100, when the length of the connecting pipes 6, 8 meets a predetermined condition, the first method can be used to accurately detect refrigerant leakage from the refrigerant circuit 10.

Note that because the first method is capable of detecting small amounts of refrigerant leakage, depending on the length of the connecting pipes 6, 8, there is a possibility that the first method may erroneously detect a refrigerant leak when no refrigerant leakage is occurring. In response to this, the air conditioning device 100 has a second mode that uses the second method in addition to a first mode that uses the first method, and can use the second mode when there is a possibility of a false detection using the first method.

(5-5)
In the air-conditioning apparatus 100, the refrigerant circuit 10 has a compressor 21, a condenser, and an evaporator, which are connected by refrigerant piping. During cooling operation, the first heat exchanger 23 functions as a condenser, and the second heat exchanger 41 functions as an evaporator. During heating operation, the second heat exchanger 41 functions as a condenser, and the first heat exchanger 23 functions as an evaporator.

The control unit 52 detects the degree of supercooling of the refrigerant at the outlet of the condenser and the first degree of superheat based on the measured values of the sensors 31-35 and 44. The first degree of superheat is either the discharge superheat of the refrigerant at the compressor 21 or the superheat of the refrigerant at the outlet of the evaporator. In the first mode, the control unit 52 controls the operation of the air conditioning device 100 so that the degree of supercooling becomes a third target value as an example of a target value, and if the first degree of superheat exceeds the first value before the degree of supercooling becomes the third target value, the control unit 52 lowers the third target value of the degree of supercooling, and if the third target value becomes a value that is lower than the initial value (initial target value) by a second value or more, determines that refrigerant is leaking.

In this air conditioning device 100, by using this method when the length of the connecting pipes 6, 8 meets certain conditions, refrigerant leakage can be detected with high accuracy.

(5-6)
The air conditioning apparatus 100 has a communication unit 56 or a remote control 60 as an acquisition unit that acquires information related to the lengths of the connection pipes 6 , 8 .

In the air conditioning device 100 of the sixth aspect, refrigerant leakage can be detected with high accuracy by changing the detection method according to the actual length of the interconnecting pipes 6, 8 acquired by the communication unit 56 or the remote control 60 as an acquisition unit.

(5-7)
The air-conditioning apparatus 100 is of a chargeless type in which the heat source unit 2 is filled in advance with a predetermined amount of refrigerant.

In the air conditioning unit 100, a predetermined amount of refrigerant is pre-filled, so depending on the length of the connecting pipes 6, 8, a state in which there is a relatively large amount of surplus refrigerant and a state in which there is a relatively small amount of surplus refrigerant may occur. In response to this, the air conditioning unit 100 can accurately detect refrigerant leaks by changing the detection method depending on the length of the connecting pipes 6, 8.

(5-8)
The method of determining refrigerant leakage of the present disclosure is a method in an air-conditioning apparatus 100 including a refrigerant circuit 10 having communication pipes 6, 8 connecting a heat source unit 2 and a utilization unit 4, sensors 31-35, 44 for measuring the temperature or pressure of refrigerant at predetermined locations in the refrigerant circuit 10, and a control unit 52, in which the control unit 52 determines whether or not refrigerant leakage has occurred from the refrigerant circuit 10 based on the measured values of the sensors 31-35, 44. The method of determining refrigerant leakage includes a step in which the control unit 52 determines whether or not the length of the communication pipes 6, 8 satisfies a predetermined condition, and a step in which the control unit 52 determines whether or not there is refrigerant leakage from the refrigerant circuit 10 by a first method when the length of the communication pipes 6, 8 satisfies the predetermined condition, and a step in which the control unit 52 determines whether or not there is refrigerant leakage from the refrigerant circuit 10 by a second method different from the first method when the length of the communication pipes 6, 8 does not satisfy the predetermined condition.

This method of determining refrigerant leakage uses different detection methods depending on the length of the interconnecting pipes 6, 8, so refrigerant leakage can be detected with high accuracy regardless of the length of the interconnecting pipes 6, 8.

(5-9)
The method of determining a refrigerant leak of the present disclosure includes a step in which, when the control unit 52 and a monitoring device 200 that receives a refrigerant leak notification output by the control unit 52 when the control unit 52 determines that a refrigerant leak is occurring from the refrigerant circuit 10 are communicatively connected, the communication unit 56 or the remote control 60, as an acquisition unit of the air conditioning device 100, acquire information regarding the length of the connecting pipes 6, 8.

In this method of determining refrigerant leakage, refrigerant leakage can be detected with high accuracy by changing the detection method depending on the actual length of the interconnecting pipes 6, 8 acquired by the communication unit 56 or the remote control 60 as an acquisition unit.

(6) Modifications Modifications of the above embodiment will now be described. Note that the configuration of each modification described below may be combined with part or all of the configuration of other modifications, as long as there is no contradiction.

(6-1) Modification A
In the air conditioning device 100 according to the above embodiment, in order to determine the presence or absence of refrigerant leakage, the control unit 52 executes the first mode when the length of the communication pipes 6, 8 is shorter than a threshold value, and executes the second mode when the length of the communication pipes 6, 8 is longer than the threshold value. However, the present invention is not limited to this embodiment.

For example, in order to determine whether or not a refrigerant leak has occurred, the control unit 52 may execute both the first mode and the second mode when the length of the communication pipes 6, 8 is shorter than a threshold value, and execute only the second mode when the length of the communication pipes 6, 8 is longer than the threshold value. In this case, when the length of the communication pipes 6, 8 is shorter than the threshold value, the control unit 52 may determine that a refrigerant leak has occurred, for example, when it is determined that a refrigerant leak has occurred in either the first mode or the second mode.

Also, for example, the control unit 52 may execute the first mode to determine whether or not there is a refrigerant leak only when the length of the connecting pipes 6, 8 is shorter than the threshold value and longer than a second threshold value (< threshold value), and execute the second mode in other cases. This is because when the length of the connecting pipes 6, 8 is extremely short, the accuracy of detecting a refrigerant leak does not increase significantly even if the first mode is used.

(6-2) Modification B
The first method executed in the first mode and the second method executed in the second mode are not limited to those described in the above embodiment. For example, the first method may be a method for determining a refrigerant leak other than that described in the above embodiment, which is suitable for a case in which the communication pipe length is relatively short. Moreover, the second method may be a method for determining a refrigerant leak other than that described in the above embodiment, which is suitable for a case in which the communication pipe length is relatively long.

For example, the first method may be a method of determining whether or not there is a refrigerant leak based on the relationship between the degree of subcooling and the target value of the degree of subcooling when the downstream expansion valve performing dryness control (the second expansion valve 26 during cooling operation, and the first expansion valve 25 during heating operation) is fully open. Specifically, in this method, for example, it is determined that there is a refrigerant leak when the degree of subcooling does not reach the target value of the degree of subcooling when the downstream expansion valve performing dryness control is fully open.

For example, the first method may be a method of determining whether or not there is a refrigerant leak based on the relationship between the discharge temperature of the first expansion valve 25 and the compressor 21 during cooling operation, and based on the relationship between the discharge temperature of the second expansion valve 26 and the compressor 21 during heating operation. Specifically, in this method, it is determined that there is a refrigerant leak when the discharge temperature of the compressor 21 is higher than a predetermined value set corresponding to the opening degree of the expansion valves 25, 26.

The second method may be, for example, to determine that refrigerant is leaking when the discharge temperature of the compressor 21 becomes too high (when an abnormality in the discharge temperature of the compressor 21 occurs) during operation of the air conditioning device 100.

For example, if the air conditioning device 100 further includes a sensor that measures the pressure of the refrigerant, the second method may be to determine whether or not there is a refrigerant leak based on the deviation between the actual discharge temperature and the discharge temperature predicted from the rotation speed, condensation temperature, and evaporation temperature of the compressor 21 while the air conditioning device 100 is operating.

The second method may be to determine whether or not there is a refrigerant leak based on the frequency with which the air conditioning device 100 executes anti-freeze control during cooling operation of the air conditioning device 100. Anti-freeze control refers to control to prevent water from freezing on the surface of the second heat exchanger 41, which is performed when the measurement value of the fourth temperature sensor 44 provided in the second heat exchanger 41 falls below 0°C.

(6-3) Modification C
In the above embodiment, the air conditioning device 100 has the receiver 24, but the present disclosure is not limited to this. For example, the refrigeration cycle device of the present disclosure may be a device that does not have the receiver 24 and the second expansion valve 26, and has an accumulator 24a provided in the suction pipe 37a, as in the air conditioning device 100A shown in Fig. 6. In this air conditioning device 100A, the control unit 52 controls the degree of subcooling by adjusting the opening degree of the first expansion valve 25 during cooling operation.

(6-4) Modification D
The communication pipe length information received by the communication unit 56 or the remote control 60 as an acquisition unit may include information that the communication pipe length is unknown.

If the communication pipe length information indicates that the communication pipe length is unknown, it is preferable that the control unit 52 executes the refrigerant leakage judgment in the second mode. By configuring in this manner, it is possible to reduce the possibility of erroneously judging that there is a refrigerant leakage when there is no refrigerant leakage when the communication pipe length is relatively long.

<Additional Notes>
Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure described in the claims.

2 Heat source unit 4 Utilization unit 6 Liquid refrigerant connection pipe (connection pipe)
8. Gas refrigerant connecting piping (connecting piping)
10 Refrigerant circuit 21 Compressor 23 First heat exchanger (condenser, evaporator)
31 Intake temperature sensor (sensor)
32 Discharge temperature sensor (sensor)
33 First temperature sensor (sensor)
34 Second temperature sensor (sensor)
35 Third temperature sensor (sensor)
44 Fourth temperature sensor (sensor)
41 Second heat exchanger (evaporator, condenser)
52 Control unit 56 Communication unit (acquisition unit)
60 Remote control (acquisition unit)
100 Air conditioning device (refrigeration cycle device)
200 Monitoring device

JP 2006-23072 A

Claims (8)

a refrigerant circuit (10) having communication pipes (6, 8) connecting a heat source unit (2) and a utilization unit (4);
A sensor (31 to 35, 44) for measuring a temperature or a pressure of a refrigerant at a predetermined location in the refrigerant circuit;
a control unit (52) that determines whether or not a refrigerant leaks from the refrigerant circuit based on a measurement value of the sensor;
A refrigeration cycle device comprising :
The control unit executes a first mode in which a first method is used to determine whether or not a refrigerant leaks from the refrigerant circuit when the length of the communication pipe satisfies a predetermined condition, and executes a second mode in which a second method different from the first method is used to determine whether or not a refrigerant leaks from the refrigerant circuit when the length of the communication pipe does not satisfy a predetermined condition ,
The refrigerant circuit includes a compressor (21), a condenser (23, 41), and an evaporator (41, 23) that are connected by a refrigerant pipe,
The control unit detects a degree of subcooling of the refrigerant at the outlet of the condenser and a first degree of superheat, which is either a discharge superheat of the refrigerant at the compressor or a superheat of the refrigerant at the outlet of the evaporator, based on a measurement value of the sensor;
The control unit, in the first mode, controls the operation of the refrigeration cycle device so that the degree of supercooling becomes a target value, and when the first degree of superheat exceeds a first value before the degree of supercooling becomes the target value, reduces the target value of the degree of supercooling, and when the target value becomes a value lower than an initial target value by a second value or more, determines that refrigerant is leaking.
Refrigeration cycle device (100, 100A). The predetermined condition is that the length of the communication pipe is shorter than a threshold value.
The refrigeration cycle device according to claim 1. The sensor includes a plurality of sensors ;
In the first mode, the control unit determines whether or not there is a refrigerant leak from the refrigerant circuit based on measurement values of the sensors included in a first combination selected from the plurality of sensors , and in the second mode, determines whether or not there is a refrigerant leak from the refrigerant circuit based on measurement values of the sensors included in a second combination selected from the plurality of sensors and different from the first combination.
The refrigeration cycle device according to claim 1 or 2. The first method is capable of detecting a smaller amount of refrigerant leakage than the second method.
The refrigeration cycle device according to any one of claims 1 to 3. Further comprising an acquisition unit (56, 60) for acquiring information regarding the length of the communication pipe,
The refrigeration cycle device according to any one of claims 1 to 4 . The heat source unit is a chargeless type in which a predetermined amount of refrigerant is charged in advance.
The refrigeration cycle device according to any one of claims 1 to 5 . A refrigeration cycle apparatus (100) including a refrigerant circuit (10) having a communication pipe (6, 8) connecting a heat source unit (2) and a utilization unit (4), a compressor (21), a condenser (23, 41), and an evaporator (41, 23) connected by refrigerant pipes, sensors (31-35, 44) measuring a temperature or pressure of a refrigerant at a predetermined location in the refrigerant circuit, and a control unit (52), the control unit determining whether a refrigerant has leaked from the refrigerant circuit based on a measurement value of the sensor,
The control unit detects a degree of subcooling of the refrigerant at an outlet of the condenser and a first degree of superheat, which is either a discharge superheat degree of the refrigerant at the compressor or a superheat degree of the refrigerant at an outlet of the evaporator, based on a measurement value of the sensor;
A step (S22) in which the control unit determines whether or not the length of the communication pipe satisfies a predetermined condition;
a step in which, when the length of the communication pipe satisfies a predetermined condition, the control unit determines whether or not there is refrigerant leakage from the refrigerant circuit by a first method, in which, in the first method, the control unit controls the operation of the refrigeration cycle device so that the degree of subcooling becomes a target value, and, when the first degree of superheat exceeds a first value before the degree of subcooling becomes the target value, the control unit lowers the target value of the degree of subcooling, and, when the target value becomes a value lower than an initial target value by a second value or more, determines that refrigerant is leaking; and, when the length of the communication pipe does not satisfy a predetermined condition, the control unit determines whether or not there is refrigerant leakage from the refrigerant circuit by a second method different from the first method.
A method for determining a refrigerant leak comprising: a step in which, when the control unit and a monitoring device (200) that receives a notification of a refrigerant leakage output by the control unit when the control unit determines that a refrigerant leakage is occurring from the refrigerant circuit are communicably connected, an acquisition unit (56, 60) of the refrigeration cycle device acquires information regarding the length of the communication pipe;
The method of claim 7 further comprising: