GB2547583A

GB2547583A - Air-conditioning Device

Info

Publication number: GB2547583A
Application number: GB1707892.4A
Authority: GB
Inventors: Ishimura Katsuhiro
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2014-12-01
Filing date: 2014-12-01
Publication date: 2017-08-23
Anticipated expiration: 2034-12-01
Also published as: JP6300954B2; WO2016088167A1; JPWO2016088167A1; GB2547583B; GB201707892D0

Abstract

The objective is to obtain an air-conditioning device (100) for which the amount of refrigerant leakage is further reduced when a refrigerant leak occurs, regardless of whether the operating mode is a cooling operation or a heating operation, for example. Therefore, the present invention is equipped with: a refrigerant circuit cutoff device (13); a leak sensor (31) that transmits a leak detection signal when a refrigerant leak is detected; and a control device (30) having a refrigerant leakage suppression function for operating a compressor (10), a throttle device (41), and the refrigeration circuit cutoff device (13) when a leak detection signal is received.

Description

DESCRIPTION Title of Invention AIR-CONDITIONING APPARATUS Technical Field [0001]

The present invention relates to an air-conditioning apparatus.

Background Art [0002]

In an existing air-conditioning apparatus, such as a multi-air-conditioning apparatus for a building, the total length of refrigerant pipes connecting an outdoor unit and a plurality of indoor units may reach several hundred meters. Accordingly, the amount of refrigerant used in the air-conditioning apparatus is significantly increased. If refrigerant leakage occurs in such an air-conditioning apparatus, a large amount of refrigerant may leak into one room.

[0003]

Further, in recent years, a shift to refrigerant of low global warming potential has been demanded from the viewpoint of global warming. The refrigerant of low global warming potential, however, is often flammable. If the future sees a further shift to the refrigerant of low global warming potential, more attention to safety is required. To address such an issue, a technique has been proposed which provides, in a refrigerant circuit, a shutoff valve for stopping a flow of refrigerant to reduce the leakage amount of the refrigerant upon refrigerant leakage (see Patent Literature 1, for example).

Citation List Patent Literature [0004]

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2000-97527 Summary of Invention Technical Problem [0005]

The technique disclosed in Patent Literature 1 is capable of reducing the leakage amount of the refrigerant upon refrigerant leakage, but has an issue in that a large amount of refrigerant may leak depending on the position of the shutoff valve for stopping the flow of refrigerant or the location at which the refrigerant leakage occurs.

[0006]

The present invention has been made to address the above-described issue, and aims to obtain an air-conditioning apparatus that further reduces the leakage amount of the refrigerant upon refrigerant leakage irrespective of the mode of operation, such as cooling operation or heating operation.

Solution to Problem [0007]

An air-conditioning apparatus of an embodiment of the present invention is an air-conditioning apparatus including a compressor, a refrigerant flow switching device, a first heat exchanger, a first expansion device, and a second heat exchanger connected together by pipes to configure a refrigeration cycle, the air-conditioning apparatus comprising: a refrigerant circuit shutoff device provided between the first heat exchanger and the first expansion device and capable of stopping a flow of refrigerant; a leakage sensor configured to detect leakage of the refrigerant and transmit a leakage detection signal; and a controller configured to operate the compressor, the first expansion device, and the refrigerant circuit shutoff device, the controller being configured to, in a case of receiving the leakage detection signal from the leakage sensor while the compressor is operating, stop the compressor and, in a case of receiving the leakage detection signal from the leakage sensor while the compressor is not operating, keep the compressor not operating and reduce an opening degree of each of the first expansion device and the refrigerant circuit shutoff device to less than a currently set opening degree Advantageous Effects of Invention [0008]

According to the air-conditioning apparatus of an embodiment of the present invention, if the compressor is not operating, the controller, which has a refrigerant leakage suppression function of operating the compressor, the first expansion device, and the refrigerant circuit shutoff device, keeps the compressor not operating, and reduces the opening degree of each of the first expansion device and the refrigerant circuit shutoff device to be less than the currently set opening degree, to thereby enable an effective reduction in the leakage amount of the refrigerant.

Brief Description of Drawings [0009] [Fig. 1] Fig. 1 is a schematic circuit configuration diagram illustrating an example of a circuit configuration of an air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a refrigerant circuit diagram illustrating a flow of refrigerant in a cooling operation mode of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 is a refrigerant circuit diagram illustrating a flow of refrigerant in a heating operation mode of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 4] Fig. 4 is a flowchart illustrating an operation preceding the start of refrigerant leakage prevention control of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 5] Fig. 5 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode or the heating operation mode of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 6] Fig. 6 is a flowchart illustrating an operation of the refrigerant leakage prevention control in a stop mode or a thermo-off mode of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 7] Fig. 7 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode of an air-conditioning apparatus according to Embodiment 2 of the present invention.

[Fig. 8] Fig. 8 is a schematic circuit configuration diagram illustrating an example of a circuit configuration of an air-conditioning apparatus according to Embodiment 3 of the present invention.

[Fig. 9] Fig. 9 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode of the air-conditioning apparatus according to Embodiment 3 of the present invention.

[Fig. 10] Fig. 10 is a schematic circuit configuration diagram illustrating an example of a circuit configuration of an air-conditioning apparatus according to Embodiment 4 of the present invention.

[Fig. 11] Fig. 11 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode of the air-conditioning apparatus according to Embodiment 4 of the present invention.

[Fig. 12] Fig. 12 is a schematic circuit configuration diagram illustrating an example of a circuit configuration of an air-conditioning apparatus according to Embodiment 5 of the present invention.

[Fig. 13] Fig. 13 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode in a case in which a bypass opening and closing device 14 of the air-conditioning apparatus according to Embodiment 5 of the present invention is a device having a changeable opening degree.

[Fig. 14] Fig. 14 is a schematic circuit configuration diagram illustrating a modified example of the circuit configuration of the air-conditioning apparatus according to Embodiment 5 of the present invention.

[Fig. 15] Fig. 15 is a schematic circuit configuration diagram illustrating an example of a circuit configuration in a case in which the air-conditioning apparatus according to one of Embodiments 1 to 5 of the present invention includes a plurality of outdoor units.

[Fig. 16] Fig. 16 is a schematic circuit configuration diagram illustrating an example of the circuit configuration in the case in which the air-conditioning apparatus according to one of Embodiments 1 to 5 of the present invention includes a plurality of outdoor units.

Description of Embodiments [0010]

Embodiments 1 to 5 of an air-conditioning apparatus 100 of the present invention will be described below with reference to the drawings. Forms in the drawings are merely illustrative, and do not limit the present invention. Further, parts assigned with same signs in the drawings are same as or correspond to each other, which applies to the entire text of the specification. Further, in the following drawings, the dimensional relationships between component members may be different from actual ones.

[0011]

Embodiment 1

Fig. 1 is a schematic circuit configuration diagram illustrating an example of a circuit configuration of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. A detailed configuration of the air-conditioning apparatus 100 will be described based on Fig. 1. The air-conditioning apparatus 100 circulates refrigerant through a circuit to perform air-conditioning using a refrigeration cycle, and is capable of selecting between a cooling only operation mode in which all operating indoor units perform cooling and a heating only operation mode in which all of the indoor units perform heating, like a multi-air-conditioning apparatus for a building, for example. As illustrated in Fig. 1, an outdoor unit 1 and indoor units 2a and 2b are connected together by a main refrigerant pipe 3. Fig. 1 illustrates an example in which the two indoor units 2a and 2b are connected to the outdoor unit 1.

[0012] [Outdoor Unit 1]

The outdoor unit 1 is equipped with a compressor 10, a refrigerant flow switching device 11, such as a four-way valve, a heat source-side heat exchanger 12, and a refrigerant circuit shutoff device 13, which are connected together by a refrigerant pipe 4. Further, a fan 6 is provided near the heat source-side heat exchanger 12. The fan 6 blows air to the heat source-side heat exchanger 12.

The heat source-side heat exchanger 12 corresponds to a "first heat exchanger" of the present invention. Further, the fan 6 corresponds to a "first fan" of the present invention.

[0013]

The compressor 10, which suctions low-temperature, low-pressure refrigerant and compresses the refrigerant into a high-temperature, high-pressure state, may preferably be configured of a capacity-controllable inverter compressor, for example. The refrigerant flow switching device 11 performs switching between a flow of the refrigerant in a cooling operation mode and a flow of the refrigerant in a heating operation mode.

[0014]

The heat source-side heat exchanger 12, which functions as a condenser in a cooling operation and functions as an evaporator in a heating operation, exchanges heat between the refrigerant and air supplied by the fan 6, such as a fan, for example. The refrigerant circuit shutoff device 13, which shuts off the flow of the refrigerant circulating through the refrigerant pipe 4, may preferably be configured of any device capable of shutting off the flow of the refrigerant, such as a solenoid valve, for example.

[0015]

The outdoor unit 1 is provided with a first pressure detecting device 20 and a second pressure detecting device 21 each as a pressure detecting device. The first pressure detecting device 20 is provided to a part of the refrigerant pipe 4 connecting a discharge side of the compressor 10 and the refrigerant flow switching device 11, and detects a pressure P1 of the high-temperature, high-pressure refrigerant compressed and discharged by the compressor 10. Further, the second pressure detecting device 21 is provided to a part of the refrigerant pipe 4 connecting the refrigerant flow switching device 11 and a suction side of the compressor 10, and detects a pressure P2 of the low-temperature, low-pressure refrigerant suctioned by the compressor 10.

[0016]

The outdoor unit 1 is further provided with a first temperature detecting device 22 as a temperature detecting device. The first temperature detecting device 22 is provided to the part of the refrigerant pipe 4 connecting the discharge side of the compressor 10 and the refrigerant flow switching device 11, and detects a temperature T1 of the high-temperature, high-pressure refrigerant compressed and discharged by the compressor 10. The first temperature detecting device 22 may preferably be configured of a device such as a thermistor.

[0017] [Indoor Units 2a and 2b]

The indoor unit 2a is equipped with a fan 7a, a load-side heat exchanger 40a, and an expansion device 41a, and the indoor unit 2b is equipped with a fan 7b, a load-side heat exchanger 40b, and an expansion device 41 b. The indoor units 2a and 2b are connected to the outdoor unit 1 via the main refrigerant pipe 3 to allow the refrigerant to flow to and from the indoor units 2a and 2b. Each of the load-side heat exchangers 40a and 40b exchanges heat between the refrigerant and air supplied by the corresponding one of the fans 7a and 7b, such as a fan, for example, to generate heating air or cooling air to be supplied to an indoor space. Further, each of the expansion devices 41a and 41 b, which functions as a pressure reducing valve or an expansion valve, reduces the pressure of the refrigerant to expand the refrigerant, and may preferably be configured of a device having an opening degree controllable to be changed, such as an electronic expansion valve, for example.

[0018]

Each of the expansion devices 41a and 41b corresponds to a "first expansion device" of the present invention. Further, each of the load-side heat exchangers 40a and 40b corresponds to a "second heat exchanger" of the present invention.

Further, each of the fans 7a and 7b corresponds to a "second fan" of the present invention.

[0019]

The indoor unit 2a has a second temperature detecting device 50a provided to a pipe connecting the expansion device 41a and the load-side heat exchanger 40a, and the indoor unit 2b has a second temperature detecting device 50b provided to a pipe connecting the expansion device 41 b and the load-side heat exchanger 40b.

Further, a third temperature detecting device 51a is provided to a pipe opposite to the expansion device 41a with respect to the load-side heat exchanger 40a, and a third temperature detecting device 51b is provided to a pipe opposite to the expansion device 41 b with respect to the load-side heat exchanger 40b. Moreover, a fourth temperature detecting device 52a is provided to an air suction unit of the load-side heat exchanger 40a, and a fourth temperature detecting device 52b is provided to an air suction unit of the load-side heat exchanger 40b.

[0020]

The second temperature detecting device 50a detects the temperature of the refrigerant flowing into the load-side heat exchanger 40a in the cooling operation, and the second temperature detecting device 50b detects the temperature of the refrigerant flowing into the load-side heat exchanger 40b in the cooling operation. Further, the third temperature detecting device 51a detects the temperature of the refrigerant flowing from the load-side heat exchanger 40a, and the third temperature detecting device 51 b detects the temperature of the refrigerant flowing from the load-side heat exchanger 40b. Moreover, each of the fourth temperature detecting devices 52a and 52b detects the air temperature in a room. Each of the temperature detecting devices may preferably be configured of a device such as a thermistor, for example.

[0021]

The air-conditioning apparatus 100 includes a controller 30 and leakage sensors 31, the controller 30 being configured of a device such as a microcomputer. The leakage sensors 31 directly or indirectly detect the leakage of the refrigerant.

The controller 30 has a refrigerant leakage signal reception function of receiving an output signal from each of the leakage sensors 31 concerning the occurrence or nonoccurrence of the refrigerant leakage. The controller 30 further has a refrigerant leakage suppression function of operating devices such as the compressor 10, the refrigerant flow switching device 11, the expansion devices 41a and 41b, and the refrigerant circuit shutoff device 13 when receiving the signal indicating the occurrence of the refrigerant leakage.

[0022]

Further, based on values detected by a variety of detecting devices and an instruction from a remote controller, the controller 30 controls factors such as the frequency of the compressor 10, the rotation speed (including ON and OFF) of the fan 6 for the heat source-side heat exchanger 12, the switching of the refrigerant flow switching device 11, and the respective opening degrees of the expansion devices 41a and 41b, to thereby execute later-described operation modes. Fig. 1 illustrates an example in which the controller 30 is provided to the outdoor unit 1 and the leakage sensor 31 is provided to each of the indoor units 2a and 2b. However, the controller 30 and the leakage sensor 31 may be individually provided to each of the units: the outdoor unit 1 and the indoor units 2a and 2b, or may be provided to the outdoor unit 1 or one of the indoor units 2a and 2b. This also applies to Figs. 2, 3, 8, 10, 12, 14, and 15 described later.

[0023] [Cooling Operation Mode]

Fig. 2 is a refrigerant circuit diagram illustrating a flow of the refrigerant in the cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. As illustrated in Fig. 2, the flow direction of the refrigerant is indicated by solid arrows. With Fig. 2, the cooling operation mode will be described with reference to an example in which a cooling load is generated in each of the load-side heat exchangers 40a and 40b.

[0024]

In the cooling operation mode, the low-temperature, low-pressure refrigerant is compressed by the compressor 10 and discharged as high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source-side heat exchanger 12 via the refrigerant flow switching device 11. The high-temperature, high-pressure gas refrigerant flowing into the heat source-side heat exchanger 12 condenses into high-pressure liquid refrigerant while rejecting heat to the outdoor air. Then, the high-pressure liquid refrigerant flowing from the heat source-side heat exchanger 12 passes through the refrigerant circuit shutoff device 13 in the open state, and flows from the outdoor unit 1 into the indoor units 2a and 2b through the main refrigerant pipe 3.

[0025]

If the refrigerant circuit shutoff device 13 is a device having a non-adjustable opening degree, such as a solenoid valve, the refrigerant circuit shutoff device 13 in the cooling operation mode may preferably be opened. If the refrigerant circuit shutoff device 13 is a device having an adjustable opening area, such as an electronic expansion valve, the refrigerant circuit shutoff device 13 in the cooling operation mode may preferably be set to an opening degree with which the operating state of the refrigeration cycle (such as cooling capacity, for example) is not adversely affected (fully open, for example).

[0026]

The high-pressure liquid refrigerant flowing into the indoor units 2a and 2b is reduced in pressure into low-temperature, low-pressure two-phase refrigerant by the expansion devices 41a and 41b, and thereafter flows into the load-side heat exchangers 40a and 40b, each of which acts as an evaporator. The low-temperature, low-pressure two-phase refrigerant then receives heat from the indoor air to thereby cool the indoor air, and turns into low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant flowing from the load-side heat exchangers 40a and 40b flows into the outdoor unit 1 through the main refrigerant pipe 3. The refrigerant flowing into the outdoor unit 1 is suctioned into the compressor 10 through the refrigerant flow switching device 11.

[0027]

The opening degree of each of the expansion devices 41 a and 41 b is controlled by the controller 30 such that the degree of superheat, which is obtained as the difference between the temperature detected by the second temperature detecting device 50a and the temperature detected by the third temperature detecting device 51a and as the difference between the temperature detected by the second temperature detecting device 50b and the temperature detected by the third temperature detecting device 51b, is maintained to be constant.

[0028] [Heating Operation Mode]

Fig. 3 is a refrigerant circuit diagram illustrating a flow of the refrigerant in the heating operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. As illustrated in Fig. 3, the flow direction of the refrigerant is indicated by solid arrows. With Fig. 3, the heating operation mode will be described with reference to an example in which a heating load is generated in each of the load-side heat exchangers 40a and 40b.

[0029]

In the heating operation mode, the low-temperature, low-pressure refrigerant is compressed by the compressor 10 and discharged as high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the indoor units 2a and 2b through the main refrigerant pipe 3 via the refrigerant flow switching device 11. The high-temperature, high-pressure gas refrigerant flowing into the indoor units 2a and 2b rejects heat to the indoor air in the load-side heat exchangers 40a and 40b to turn into high-pressure liquid refrigerant, and flows into the expansion devices 41a and 41b. Then, the high-pressure liquid refrigerant is subjected to pressure reduction by the expansion devices 41a and 41b to turn into low-temperature, low-pressure two-phase refrigerant, and thereafter flows from the indoor units 2a and 2b into the outdoor unit 1 through the main refrigerant pipe 3.

[0030]

The low-temperature, low-pressure two-phase refrigerant flowing into the outdoor unit 1 passes through the refrigerant circuit shutoff device 13 in the open state, and receives heat from the outdoor air in the heat source-side heat exchanger 12 to thereby turn into low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant flowing from the heat source-side heat exchanger 12 is suctioned into the compressor 10 through the refrigerant flow switching device 11.

[0031]

If the refrigerant circuit shutoff device 13 is a device having a non-adjustable opening degree, such as a solenoid valve, the refrigerant circuit shutoff device 13 in the heating operation mode may preferably be opened. If the refrigerant circuit shutoff device 13 is a device having an adjustable opening area, such as an electronic expansion valve, the refrigerant circuit shutoff device 13 in the heating operation mode may preferably be set to an opening degree with which the operating state of the refrigeration cycle (such as heating capacity, for example) is not adversely affected (fully open, for example).

[0032]

The opening degree of each of the expansion devices 41a and 41b is controlled by the controller 30 such that the degree of subcooling, which is obtained as the difference between the saturated liquid temperature of the refrigerant calculated from the pressure detected by the first pressure detecting device 20 and the temperature detected by the corresponding one of the second temperature detecting devices 50a and 50b, is maintained to be constant.

[0033] [Refrigerant Leakage Signal Reception Function]

The refrigerant leakage signal reception function of the controller 30 will be described. The leakage sensor 31, which is installed to at least one location, such as a space installed with the indoor units 2a and 2b, the interior of a housing of the outdoor unit 1, or the vicinity of a place installed with the outdoor unit 1, detects the leakage of the refrigerant and transmits a signal. Further, the refrigerant leakage signal reception function as one of functions of the controller 30 is a function of receiving the signal from the leakage sensor 31.

[0034]

For example, a configuration may preferably be made such that the controller 30 of the air-conditioning apparatus 100 is connected by electrical wiring to the leakage sensor 31, which has a detection method of directly detecting the concentration of the refrigerant or indirectly detecting the concentration of the refrigerant through detection of the oxygen concentration, and that an electrical signal is transmitted to the controller 30 by the leakage sensor 31 upon detection of the leakage of the refrigerant and is received by the refrigerant leakage signal reception function of the controller 30. Although the leakage sensor 31 and the controller 30 of the air-conditioning apparatus 100 are connected together by electrical wiring in the above description, the configuration is not limited thereto. Any method may be employed, as long as the method allows the transmission of the signal from the leakage sensor 31 to the controller 30 of the air-conditioning apparatus 100.

[0035] [Refrigerant Leakage Suppression Function]

The refrigerant leakage suppression function (control) of the controller 30 will now be described. Fig. 4 is a flowchart illustrating an operation preceding the start of the refrigerant leakage prevention control of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. With reference to Fig. 1, a control operation of the refrigerant leakage suppression function will be described below based on steps of Fig. 4.

[0036] (Step A1)

It is determined whether the refrigerant leakage signal reception function has received from the leakage sensor 31 the signal indicating that the refrigerant leakage has occurred. If the refrigerant leakage signal reception function has received the signal, the procedure proceeds to step A2. If the refrigerant leakage signal reception function has not received the signal, the control operation of the refrigerant leakage suppression function is completed. (Step A2)

The controller 30 identifies the operation mode at the time of receipt of the refrigerant leakage signal. (Step A3)

The controller 30 executes the refrigerant leakage prevention control of preventing the leakage of the refrigerant according to the operation mode.

[0037] [Refrigerant Leakage Prevention Control in Cooling Operation Mode]

Fig. 5 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode or the heating operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. With reference to Fig. 2, the refrigerant leakage prevention control in the event of refrigerant leakage during the operation of the air-conditioning apparatus 100 in the cooling operation mode will be described below based on steps of Fig. 5.

[0038] (Step B1)

The controller 30 stops the compressor 10. (Step B2)

The controller 30 fully closes the expansion devices 41 a and 41 b. (Step B3)

The controller 30 fully closes the refrigerant circuit shutoff device 13. (Step B4)

The controller 30 operates the fans 7a and 7b for the load-side heat exchangers 40a and 40b. (Step B5)

The controller 30 operates the fan 6 for the heat source-side heat exchanger 12.

[0039]

In the cooling operation mode, there is a large amount of liquid refrigerant between the heat source-side heat exchanger 12 and the expansion devices 41a and 41 b of the air-conditioning apparatus 100. If the refrigerant leakage occurs, therefore, the operation illustrated in Fig. 5 is executed to thereby make it possible to reduce the amount of refrigerant leaking into the space installed with the indoor units 2a and 2b, and prevent the leakage of all refrigerant filling the air-conditioning apparatus 100.

[0040]

For example, if the refrigerant leakage occurs somewhere in the section between the expansion devices 41a and 41b and the suction side of the compressor 10 in the cooling operation mode, the refrigerant in the section is all gas refrigerant except for a slight amount of liquid refrigerant present in the load-side heat exchangers 40a and 40b. It is therefore possible to substantially reduce the amount of leaking refrigerant.

[0041]

Similarly, if the refrigerant leakage occurs in the section between the refrigerant circuit shutoff device 13 and the expansion devices 41 a and 41 b, most of the refrigerant present in the section is liquid refrigerant, and thus the amount of leaking refrigerant is large. However, it is possible to prevent the leakage of the liquid refrigerant in the heat source-side heat exchanger 12.

[0042]

Further, although this is not a case in which the refrigerant leaks into the space installed with the indoor units 2a and 2b, if the refrigerant leakage occurs in the section between the discharge side of the compressor 10 and the refrigerant circuit shutoff device 13, the liquid refrigerant in the heat source-side heat exchanger 12 leaks. However, it is possible to prevent the leakage of the liquid refrigerant in the section between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41b.

[0043]

The flowchart illustrated in Fig. 5 specifies the order of operations of respective actuators. However, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations of steps B1 to B5 is changed. Further, the fan 6 for the heat source-side heat exchanger 12 is operating in the cooling operation mode, and it is desirable to operate the fan 6 at full speed to enhance the effect of diluting the leaked refrigerant. Similarly, as for the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable not only to operate the fans 7a and 7b in the stopped indoor units 2a and 2b, but also to operate the fans 7a and 7b at full speed in the operating indoor units 2a and 2b to enhance the effect of diluting the refrigerant.

[0044] [Refrigerant Leakage Prevention Control in Heating Operation Mode] A description will be given of the refrigerant leakage suppression function (control) of the controller 30 in the event of refrigerant leakage during the operation of the air-conditioning apparatus 100 in the heating operation mode. The operation of the refrigerant leakage prevention control in the heating operation mode is the same as that of the flowchart illustrating the operation of the refrigerant leakage prevention control in the cooling operation mode (see Fig. 5).

[0045]

In the heating operation mode, there is a large amount of liquid refrigerant in the section between the load-side heat exchangers 40a and 40b and the heat source-side heat exchanger 12 of the air-conditioning apparatus 100. Therefore, the operation of the refrigerant leakage prevention control illustrated in Fig. 5 is executed when the refrigerant leakage occurs in the heating operation mode. It is thereby possible to reduce the amount of refrigerant leaking into the space installed with the indoor units 2a and 2b when the refrigerant leakage occurs. It is also possible to prevent the leakage of all refrigerant filling the air-conditioning apparatus 100.

[0046]

For example, if the refrigerant leakage occurs somewhere in the section between the discharge side of the compressor 10 and the expansion devices 41a and 41b in the heating operation mode, a certain amount of refrigerant leaks owing to a large amount of liquid refrigerant present in the load-side heat exchangers 40a and 40b in the section. However, it is possible to prevent the leakage of the liquid refrigerant in the section between the expansion devices 41a and 41b and the refrigerant circuit shutoff device 13.

[0047]

Similarly, if the refrigerant leakage occurs in the section between the expansion devices 41a and 41b and the refrigerant circuit shutoff device 13, the amount of leaking refrigerant is large owing to a large amount of liquid refrigerant present in the section. However, it is possible to prevent the leakage of the liquid refrigerant in the load-side heat exchangers 40a and 40b.

[0048]

Further, although this is not a case in which the refrigerant leaks into the space installed with the indoor units 2a and 2b, if the refrigerant leakage occurs in the section between the refrigerant circuit shutoff device 13 and the suction side of the compressor 10, it is possible to substantially reduce the amount of leaking refrigerant owing to a small amount of liquid refrigerant present in the section.

[0049]

The flowchart illustrated in Fig. 5 specifies the order of operations of respective actuators. However, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations of steps B1 to B5 is changed. Further, the fan 6 for the heat source-side heat exchanger 12 is operating in the heating operation mode, and it is desirable to operate the fan 6 at full speed to enhance the effect of diluting the leaked refrigerant. Similarly, as for the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable not only to operate the fans 7a and 7b in the stopped indoor units 2a and 2b, but also to operate the fans 7a and 7b at full speed in the operating indoor units 2a and 2b to enhance the effect of diluting the refrigerant.

[0050] [Refrigerant Leakage Prevention Control in Stopped State] A description will be given of the refrigerant leakage suppression function (control) of the controller 30 in the event of refrigerant leakage in the stopped state (hereinafter referred to as the stop mode) of the air-conditioning apparatus 100. Fig. 6 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the stop mode or a thermo-off mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention. With reference to Fig. 1, the refrigerant leakage prevention control in the event of refrigerant leakage in the stop mode of the air-conditioning apparatus 100 will be described below based on steps of Fig. 6.

[0051] (Step C1)

The controller 30 fully closes the expansion devices 41 a and 41 b. (Step C2)

The controller 30 fully closes the refrigerant circuit shutoff device 13. (Step C3)

The controller 30 operates the fans 7a and 7b for the load-side heat exchangers 40a and 40b. (Step C4)

[0052]

In the stop mode, the location of the liquid refrigerant in the air-conditioning apparatus 100 is affected by factors such as indoor and outdoor temperature conditions and the time elapsed after the stop of the air-conditioning apparatus 100. Thus, the area of presence of the liquid refrigerant changes moment to moment. Therefore, all closable actuators are closed to prevent the leakage of all refrigerant in the air-conditioning apparatus 100.

[0053]

The flowchart illustrated in Fig. 6 specifies the order of operations of respective actuators. However, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations of steps C1 to C4 is changed. Further, when operating the fan 6 for the heat source-side heat exchanger 12 or the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable to operate the fan 6 or the fans 7a and 7b at full speed or at nearly full speed to enhance the effect of diluting the leaked refrigerant.

[0054] [Refrigerant Leakage Prevention Control in Thermo-off State] A description will be given of the refrigerant leakage prevention control in the event of refrigerant leakage in the thermo-off state (hereinafter referred to as the thermo-off mode) of the air-conditioning apparatus 100. The operation of the refrigerant leakage prevention control in the thermo-off mode is the same as that of the flowchart illustrating the operation of the refrigerant leakage prevention control in the stop mode (see Fig. 6).

[0055]

In the thermo-off mode, the location of the liquid refrigerant in the air-conditioning apparatus 100 is affected by factors such as indoor and outdoor temperature conditions and the time elapsed after the thermo-off of the air-conditioning apparatus 100. Thus, the area of presence of the liquid refrigerant changes moment to moment. Therefore, all closable actuators are closed to prevent the leakage of all refrigerant in the air-conditioning apparatus 100.

[0056]

The flowchart illustrated in Fig. 6 specifies the order of operations of respective actuators. However, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations of steps C1 to C4 is changed. Further, when operating the fan 6 for the heat source-side heat exchanger 12, it is desirable to operate the fan 6 at full speed or at nearly full speed to enhance the effect of diluting the leaked refrigerant. Similarly, as for the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable not only to operate the fans 7a and 7b in the stopped indoor units 2a and 2b, but also to operate the fans 7a and 7b at full speed in the operating indoor units 2a and 2b to enhance the effect of diluting the refrigerant.

[0057]

As described above, the leakage sensor 31 detects the refrigerant leakage, and transmits to the refrigerant leakage signal reception function of the controller 30 the leakage detection signal indicating that the refrigerant leakage has occurred.

Then, the refrigerant leakage suppression function (control) of the controller 30 operates the compressor 10, the expansion devices 41a and 41b, and the refrigerant circuit shutoff device 13 in accordance with each of the operation modes, thereby enabling an effective reduction in the leakage amount of the refrigerant.

[0058]

The refrigerant leakage prevention control of reducing the leakage amount of the refrigerant is executed for each of the operation modes. Depending on the combination of the operation mode and the location of the refrigerant leakage, more attention to safety is required. Therefore, a controller having at least one of a function of displaying a notice that the refrigerant leakage has occurred and a function of sounding an alarm is used as the controller 30. By so doing, the safety in the indoor space is further improved. This also applies to Embodiments 2 to 5 described later.

[0059]

Further, the controller 30 receives, from the leakage sensor 31 that detects the refrigerant leakage, the leakage detection signal notifying the occurrence of the refrigerant leakage, and controls the refrigerant circuit shutoff device 13.

Furthermore, if the main refrigerant pipe 3 connecting the outdoor unit 1 and the indoor units 2a and 2b is provided with at least one refrigerant circuit shutoff device 13 that shuts off the flow of the refrigerant in the main refrigerant pipe 3, this configuration enables a further reduction in the leakage amount of the refrigerant.

This also applies to Embodiments 2 to 5 described later.

[0060]

Embodiment 2 A basic configuration of the air-conditioning apparatus 100 of Embodiment 2 is similar to that of the air-conditioning apparatus 100 of Embodiment 1 described above. Therefore, a description will be given below of Embodiment 2, focusing on a difference of Embodiment 2 from Embodiment 1. Embodiment 2 is different from Embodiment 1 in that the refrigerant leakage prevention control in the cooling operation mode is changed.

[0061]

In the refrigerant leakage prevention control in the cooling operation mode of Embodiment 1, the pipes between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41b may be brought into the liquid-sealed state, filled with the liquid refrigerant. If the ambient temperature rises in the liquid-sealed state, the refrigerant in the pipes undergoes gasification and applies substantially high pressure to the pipes, and may eventually rupture the pipes. This issue may be addressed by performing control of closing the expansion devices 41a and 41b and the refrigerant circuit shutoff device 13 when a first reference time elapses after the stop of the compressor 10.

[0062] [Refrigerant Leakage Prevention Control in Cooling Operation Mode]

The refrigerant leakage suppression function (control) according to Embodiment 2 will be described. Fig. 7 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 2 of the present invention.

With reference to Fig. 2, the refrigerant leakage suppression function of the controller 30 in the event of refrigerant leakage during the operation of the air-conditioning apparatus 100 in the cooling operation mode will be described below based on steps of Fig. 7.

[0063] (Step D1)

The controller 30 stops the compressor 10. (Step D2)

The controller 30 stands by until the first reference time elapses after the stop of the compressor 10. (Step D3)

The controller 30 fully closes the expansion devices 41 a and 41 b. (Step D4)

The controller 30 fully closes the refrigerant circuit shutoff device 13. (Step D5)

The controller 30 operates the fans 7a and 7b for the load-side heat exchangers 40a and 40b. (Step D6)

[0064]

With the execution of the operation of the refrigerant leakage prevention control in the cooling operation mode illustrated in Fig. 7, the expansion devices 41a and 41b and the refrigerant circuit shutoff device 13 are not fully closed immediately after the stop of the compressor 10. Therefore, the pressure difference in the refrigerant circuit is reduced, or the pressure in the refrigerant circuit is equalized, making it possible to avoid the liquid-sealed state. The first reference time is set to a time longer than 0 minutes and not exceeding 10 minutes, for example.

[0065]

The flowchart illustrated in Fig. 7 specifies the order of operations of respective actuators. Flowever, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations described in steps D3 to D6 is changed. Further, when operating the fan 6 for the heat source-side heat exchanger 12 or the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable to operate the fan 6 or the fans 7a and 7b at full speed or at nearly full speed to enhance the effect of diluting the leaked refrigerant.

[0066]

Then, the refrigerant leakage suppression function (control) of the controller 30 stops the compressor 10, and fully closes the expansion devices 41a and 41b, and the refrigerant circuit shutoff device 13 when the first reference time elapses after the stop of the compressor 10. This configuration enables an effective reduction in the leakage amount of the refrigerant. Further, the pressure difference in the refrigerant circuit is reduced, or the pressure in the refrigerant circuit is equalized, thereby making it possible to avoid the liquid-sealed state of the pipes and reduce the possibility of rupture of the pipes.

[0067]

Embodiment 3 A basic configuration of the air-conditioning apparatus 100 of Embodiment 3 is similar to that of the air-conditioning apparatus 100 of Embodiment 1 described above. Therefore, a description will be given below of Embodiment 3, focusing on differences of Embodiment 3 from Embodiment 1. Embodiment 3 is different from Embodiment 1 in two points: a change in that the refrigerant circuit shutoff device 13 is configured of an opening and closing device having a changeable opening degree (such as an electronic expansion valve, for example) and a change in the refrigerant leakage prevention control in the cooling operation mode.

[0068]

Fig. 8 is a schematic circuit configuration diagram illustrating an example of the circuit configuration of the air-conditioning apparatus 100 according to Embodiment 3 of the present invention. As illustrated in Fig. 8, the air-conditioning apparatus 100 includes a refrigerant circuit shutoff device 13a, which is an opening and closing device having a changeable opening degree (such as an electronic expansion valve, for example), in place of the refrigerant circuit shutoff device 13.

[0069]

In the refrigerant leakage prevention control in the cooling operation mode of Embodiment 1, the pipes between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41 b may be brought into the liquid-sealed state in which the pipes are filled with the liquid refrigerant. If the ambient temperature rises in the liquid-sealed state, the refrigerant in the pipes undergoes gasification and applies substantially high pressure to the pipes, and may eventually rupture the pipes. This issue may be avoided by replacing the refrigerant circuit shutoff device 13 with the refrigerant circuit shutoff device 13a, which is an opening and closing device having a changeable opening degree (such as an electronic expansion valve, for example), and changing the refrigerant leakage prevention control in the cooling operation mode.

[0070] [Refrigerant Leakage Prevention Control in Cooling Operation Mode]

The refrigerant leakage suppression function (control) according to

Embodiment 3 will now be described. Fig. 9 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 3 of the present invention.

With reference to Fig. 8, the refrigerant leakage suppression function of the controller 30 in the event of refrigerant leakage during the operation of the air-conditioning apparatus 100 in the cooling operation mode will be described below based on steps of Fig. 9.

[0071] (Step E1)

The controller 30 stops the compressor 10. (Step E2)

The controller 30 fully closes the expansion devices 41 a and 41 b. (Step E3)

The controller 30 sets the refrigerant circuit shutoff device 13a to a reference opening degree. (Step E4)

The controller 30 operates the fans 7a and 7b for the load-side heat exchangers 40a and 40b. (Step E5)

[0072]

Then, the refrigerant leakage suppression function (control) of the controller 30 stops the compressor 10, fully closes the expansion devices 41a and 41b, and sets the refrigerant circuit shutoff device 13 to the reference opening degree. This configuration enables an effective reduction in the leakage amount of the refrigerant. Further, the pressure difference in the refrigerant circuit is reduced, or the pressure in the refrigerant circuit is equalized, thereby making it possible to avoid the liquid-sealed state of the pipes and reduce the possibility of rupture of the pipes. The reference opening degree is set to make the flow rate of the refrigerant passing through the refrigerant circuit shutoff device 13 greater than 0 kg/h and equal to or less than 10 kg/h, for example. This also applies to Embodiment 5 described later.

[0073]

The flowchart illustrated in Fig. 9 specifies the order of operations of respective actuators. However, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations described in steps E2 to E5 is changed. Further, when operating the fan 6 for the heat source-side heat exchanger 12 or the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable to operate the fan 6 or the fans 7a and 7b at full speed or at nearly full speed to enhance the effect of diluting the leaked refrigerant.

[0074]

Further, although the refrigerant circuit shutoff device 13a is set to the reference opening degree in the above configuration, the configuration is not limited thereto. Thus, the expansion devices 41 a and 41 b may be set to the reference opening degree, or the refrigerant circuit shutoff device 13a and the expansion devices 41 a and 41 b may both be set to the reference opening degree. Similar effects are obtainable by such configurations.

[0075]

With the execution of the operation of the refrigerant leakage prevention control in the cooling operation mode illustrated in Fig. 9, it is possible to prevent the section between the refrigerant circuit shutoff device 13a and the expansion devices 41a and 41 b from being liquid-sealed. Wth the refrigerant circuit shutoff device 13a set to the reference opening degree, however, the refrigerant in the heat source-side heat exchanger 12 also leaks, albeit slowly. It is therefore desirable to use, as the controller 30, a controller having at least one of the function of displaying a notice that the refrigerant leakage has occurred and the function of sounding an alarm. By so doing, the safety in the indoor space is further improved.

[0076]

Embodiment 4 A basic configuration of the air-conditioning apparatus 100 of Embodiment 4 is similar to that of the air-conditioning apparatus 100 of Embodiment 1 described above. Therefore, a description will be given below of Embodiment 4, focusing on differences of Embodiment 4 from Embodiment 1. Embodiment 4 is different from Embodiment 1 in two points: a change into a configuration including a bypass and a change in the refrigerant leakage prevention control in the cooling operation mode.

[0077]

Fig. 10 is a schematic circuit configuration diagram illustrating an example of the circuit configuration of the air-conditioning apparatus 100 according to Embodiment 4 of the present invention. As illustrated in Fig. 10, the air-conditioning apparatus 100 includes a bypass pipe 5 that branches from the section between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41b, through which the high-pressure refrigerant flows in the cooling operation mode, and joins the section between the load-side heat exchangers 40a and 40b and the suction side of the compressor 10, through which the low-pressure refrigerant flows. The air-conditioning apparatus 100 further includes a bypass opening and closing device 14 provided to an intermediate portion of the bypass pipe 5 and configured of a device such as a solenoid valve.

[0078]

In the refrigerant leakage prevention control in the cooling operation mode of Embodiment 1, the pipes between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41b may be brought into the liquid-sealed state in which the pipes are filled with the liquid refrigerant. If the ambient temperature rises in the liquid-sealed state, the refrigerant in the pipes undergoes gasification and applies substantially high pressure to the pipes, and may eventually rupture the pipes. This issue may be avoided by the change into the structure including the bypass opening and closing device 14 provided to an intermediate portion of the bypass pipe 5 and configured of a device such as a solenoid valve, and the change in the refrigerant leakage prevention control in the cooling operation mode.

[0079] [Refrigerant Leakage Prevention Control in Cooling Operation Mode]

The refrigerant leakage suppression function (control) according to Embodiment 4 will now be described. Fig. 11 is a flowchart illustrating an operation of the refrigerant leakage prevention control in the cooling operation mode of the air-conditioning apparatus 100 according to Embodiment 4 of the present invention.

With reference to Fig. 10, the refrigerant leakage suppression function of the controller 30 in the event of refrigerant leakage during the operation of the air-conditioning apparatus 100 in the cooling operation mode will be described below based on steps of Fig. 11.

[0080] (Step F1)

The controller 30 stops the compressor 10. (Step F2)

The controller 30 stands by until a second reference time elapses after the stop of the compressor 10. (Step F3)

The controller 30 fully closes the expansion devices 41 a and 41 b. (Step F4)

The controller 30 fully closes the refrigerant circuit shutoff device 13. (Step F5)

The controller 30 fully closes the bypass opening and closing device 14. (Step F6)

The controller 30 operates the fans 7a and 7b for the load-side heat exchangers 40a and 40b. (Step F7)

[0081]

Then, the refrigerant leakage suppression function (control) of the controller 30 stops the compressor 10, and fully closes the expansion devices 41a and 41b, the refrigerant circuit shutoff device 13, and the bypass opening and closing device 14 after the lapse of the second reference time. This configuration enables an effective reduction in the leakage amount of the refrigerant. Further, the pressure difference in the refrigerant circuit is reduced, or the pressure in the refrigerant circuit is equalized, thereby making it possible to avoid the liquid-sealed state of the pipes and reduce the possibility of rupture of the pipes. The second reference time is set to a time longer than 0 minutes and not exceeding 10 minutes, for example.

[0082]

The flowchart illustrated in Fig. 11 specifies the order of operations of respective actuators. However, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations described in steps F3 to F7 is changed. Further, when operating the fan 6 for the heat source-side heat exchanger 12 or the fans 7a and 7b for the load-side heat exchangers 40a and 40b, it is desirable to operate the fan 6 or the fans 7a and 7b at full speed or at nearly full speed to enhance the effect of diluting the leaked refrigerant.

[0083]

Embodiment 5 A basic configuration of the air-conditioning apparatus 100 of Embodiment 5 is similar to that of the air-conditioning apparatus 100 of Embodiment 4 described above. Therefore, a description will be given below of Embodiment 5, focusing on a difference of Embodiment 5 from Embodiment 4. Embodiment 5 is different from Embodiment 4 in that the bypass opening and closing device 14 is configured of an opening and closing device having a changeable opening degree (such as an electronic expansion valve, for example).

[0084]

Fig. 12 is a schematic circuit configuration diagram illustrating an example of the circuit configuration of the air-conditioning apparatus 100 according to Embodiment 5 of the present invention. As illustrated in Fig. 12, the air-conditioning apparatus 100 includes the bypass pipe 5 that branches from the section between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41b, through which the high-pressure refrigerant flows in the cooling operation mode, and joins the section between the load-side heat exchangers 40a and 40b and the suction side of the compressor 10, through which the low-pressure refrigerant flows. The air-conditioning apparatus 100 further includes a bypass opening and closing device 14a provided to an intermediate portion of the bypass pipe 5 and configured of a device such as a solenoid valve. The bypass opening and closing device 14a is configured of an opening and closing device having a changeable opening degree (such as an electronic expansion valve, for example).

[0085] [Refrigerant Leakage Prevention Control in Cooling Operation Mode] A description will now be given of an operation of the refrigerant leakage prevention control in the cooling operation mode in the case in which the bypass opening and closing device 14a is configured of an opening and closing device having a changeable opening degree (such as an electronic expansion valve, for example). Fig. 13 is a flowchart illustrating the operation of the refrigerant leakage prevention control in the cooling operation mode in the case in which the bypass opening and closing device 14a of the air-conditioning apparatus 100 according to Embodiment 5 of the present invention is a device having a changeable opening degree. With reference to Fig. 12, the refrigerant leakage suppression function of the controller 30 in the event of refrigerant leakage during the operation of the air-conditioning apparatus 100 in the cooling operation mode will be described below based on steps of Fig. 13.

[0086] (Step G1)

The controller 30 stops the compressor 10. (Step G2)

The controller 30 fully closes the expansion devices 41 a and 41 b. (Step G3)

The controller 30 fully closes the refrigerant circuit shutoff device 13. (Step G4)

The controller 30 sets the bypass opening and closing device 14a to the reference opening degree. (Step G5)

The controller 30 operates the fans 7a and 7b for the load-side heat exchangers 40a and 40b. (Step G6)

[0087]

As described above, the leakage sensor 31 detects the refrigerant leakage, and transmits to the refrigerant leakage signal reception function of the controller 30 the leakage detection signal indicating that the refrigerant leakage has occurred. Then, the refrigerant leakage suppression function (control) of the controller 30 stops the compressor 10, fully closes the expansion devices 41a and 41b and the refrigerant circuit shutoff device 13, and sets the bypass opening and closing device 14a to the reference opening degree. This configuration enables an effective reduction in the leakage amount of the refrigerant. Further, the pressure difference in the refrigerant circuit is reduced, or the pressure in the refrigerant circuit is equalized, thereby making it possible to avoid the liquid-sealed state of the pipes and reduce the possibility of rupture of the pipes.

[0088]

The flowchart illustrated in Fig. 13, which illustrates the operation of the cooling leakage prevention control executed when the refrigerant leakage occurs in the cooling operation mode, specifies the order of operations of respective actuators. Flowever, the order of operations is not limited thereto, and similar effects are obtainable even if the order of operations described in steps G2 to G6 is changed.

[0089]

With the execution of the operation of the refrigerant leakage prevention control in the cooling operation mode illustrated in Fig. 12, it is possible to prevent the section between the refrigerant circuit shutoff device 13a and the expansion devices 41a and 41 b from being liquid-sealed. With the refrigerant circuit shutoff device 13a set to the reference opening degree, however, the refrigerant in the heat source-side heat exchanger 12 also leaks, albeit slowly. It is therefore desirable to use, as the controller 30, a controller having at least one of the function of displaying a notice that the refrigerant leakage has occurred and the function of sounding an alarm. By so doing, the safety in the indoor space is further improved.

[0090]

Fig. 12 illustrates an example in which the bypass pipe 5 is a bypass that extracts the refrigerant from the section between the refrigerant circuit shutoff device 13 and the expansion devices 41a and 41b, through which the high-pressure refrigerant flows in the cooling operation mode, and joins the section between the load-side heat exchangers 40a and 40b and the suction side of the compressor 10, through which the low-pressure refrigerant flows. The present invention, however, is not limited to this configuration.

[0091]

For example, as illustrated in Fig. 14, a circuit may be configured such that the bypass pipe 5, the bypass opening and closing device 14a, and an internal heat exchanger 15 are provided between the refrigerant circuit shutoff device 13 and the expansion devices 41 a and 41 b to increase the degree of subcooling of the heat source-side heat exchanger 12 in the cooling operation, and that the bypass pipe 5 on a low-pressure side of the internal heat exchanger 15 bypasses and joins the section between the load-side heat exchangers 40a and 40b and the suction side of the compressor 10, through which the low-pressure refrigerant flows.

[0092]

Further, although Figs. 10 and 14 illustrate a case in which the bypass pipe 5 is included in the outdoor unit 1, the configuration is not limited thereto. As long as the bypass pipe 5 is a bypass that extracts the refrigerant from the section between the refrigerant circuit shutoff device 13 or the refrigerant circuit shutoff device 13a and the expansion devices 41a and 41b, through which the high-pressure refrigerant flows, and joins the section between the load-side heat exchangers 40a and 40b and the suction side of the compressor 10, through which the low-pressure refrigerant flows, the bypass pipe 5 does not need to be included in the outdoor unit 1, and similar effects are obtainable.

[0093]

The drawings of the air-conditioning apparatus 100 of Embodiments 1 to 5 illustrate an example in which the two indoor units 2a and 2b are connected to the outdoor unit 1 via the main refrigerant pipe 3. However, the number of indoor units 2a and 2b to be connected is not limited to two, and may be one or a plural number equal to or greater than three. Further, as illustrated in Figs. 15 and 16, the number of the outdoor unit 1 is not limited to one. Thus, even if each of a plurality of outdoor units 1 executes the operations specified in each of Embodiments 1 to 5, similar effects are obtainable.

[0094]

Further, in a system connecting a plurality of indoor units 2a and 2b, all of the connected indoor units 2a and 2b may perform not only the cooling or heating operation but also a mixed operation of simultaneously performing the cooling operation and the heating operation in accordance with the indoor units 2a and 2b.

[0095]

Further, although the description of Embodiments 1 to 5 has been given of an example of a direct expansion circuit in which the outdoor unit 1 and the indoor units 2a and 2b are connected in series by the main refrigerant pipe 3, the present invention is not limited thereto. For example, even if the air-conditioning apparatus 100 is configured such that a heat medium relay unit including an expansion device and an intermediate heat exchanger that exchanges heat with a heat medium different from the refrigerant is provided at a position separated from the outdoor unit 1, and that the heat medium heated or cooled through heat exchange with the refrigerant is circulated through the load-side heat exchangers 40a and 40b, it suffices as long as the components of the refrigeration cycle are capable of executing the specified operations, and similar effects are exhibited.

[0096]

Although the description has been given of an example in which the single compressor 10 is connected to the outdoor unit 1, two or any other plural number of compressors 10 may be connected to the outdoor unit 1.

[0097]

Further, the description has been given of an example in which the air-conditioning apparatus 100 includes the refrigerant flow switching device 11 in the outdoor unit 1. However, even if the air-conditioning apparatus 100 is a system that does not include the refrigerant flow switching device 11 and performs only one of the cooling operation and the heating operation, similar effects are exhibited.

[0098]

Although the drawings of the air-conditioning apparatus 100 of Embodiments 1 to 5 may suggest that the refrigerant circuit shutoff device 13 or the refrigerant circuit shutoff device 13a is included in the outdoor unit 1, the configuration is not limited thereto. The refrigerant circuit shutoff device 13 or the refrigerant circuit shutoff device 13a may be provided at any position between the heat source-side heat exchanger 12 and the expansion devices 41a and 41b.

Reference Signs List [0099] 1 outdoor unit 2 indoor unit 3 main refrigerant pipe 4 refrigerant pipe 5 bypass pipe 6 fan 7a fan 7b fan 10 compressor 11 refrigerant flow switching device 12 heat source-side heat exchanger 13 refrigerant circuit shutoff device 13a refrigerant circuit shutoff device 14 bypass opening and closing device 14a bypass opening and closing device 15 internal heat exchanger 20 first pressure detecting device 21 second pressure detecting device 22 first temperature detecting device 30 controller 31 leakage sensor 40a load-side heat exchanger 40b load-side heat exchanger 41a expansion device 41b expansion device 50a second temperature detecting device 50b second temperature detecting device 51a third temperature detecting device 51b third temperature detecting device 52a fourth temperature detecting device 52b fourth temperature detecting device 100 air-conditioning apparatus

Claims

CLAIMS [Claim 1] An air-conditioning apparatus including a compressor, a refrigerant flow switching device, a first heat exchanger, a first expansion device, and a second heat exchanger connected together by pipes to configure a refrigeration cycle, the air-conditioning apparatus comprising: a refrigerant circuit shutoff device provided between the first heat exchanger and the first expansion device and capable of stopping a flow of refrigerant; a leakage sensor configured to detect leakage of the refrigerant and transmit a leakage detection signal; and a controller configured to operate the compressor, the first expansion device, and the refrigerant circuit shutoff device, the controller being configured to, in a case of receiving the leakage detection signal from the leakage sensor while the compressor is operating, stop the compressor and, in a case of receiving the leakage detection signal from the leakage sensor while the compressor is not operating, keep the compressor not operating and reduce an opening degree of each of the first expansion device and the refrigerant circuit shutoff device to less than a currently set opening degree. [Claim 2] The air-conditioning apparatus of claim 1, wherein the refrigerant circuit shutoff device is capable of changing an opening area of a refrigerant passage. [Claim 3] The air-conditioning apparatus of claim 1 or 2, wherein the controller is configured to fully close the first expansion device and the refrigerant circuit shutoff device. [Claim 4] The air-conditioning apparatus of claim 1 or 2, wherein the refrigerant flow switching device is configured to perform switching between a cooling operation mode for causing high-pressure refrigerant to flow through the first heat exchanger to operate the first heat exchanger as a condenser and a heating operation mode for causing low-pressure refrigerant to flow through the first heat exchanger to operate the first heat exchanger as an evaporator, and wherein, the controller is configured to, in the cooling operation mode, fully close the refrigerant circuit shutoff device and the first expansion device after lapse of a first reference time. [Claim 5] The air-conditioning apparatus of claim 1 or 2, wherein the refrigerant flow switching device is configured to perform switching between a cooling operation mode for causing high-pressure refrigerant to flow through the first heat exchanger to operate the first heat exchanger as a condenser and a heating operation mode for causing low-pressure refrigerant to flow through the first heat exchanger to operate the first heat exchanger as an evaporator, and wherein the controller is configured to, in the cooling operation mode, set at least one of the refrigerant circuit shutoff device and the first expansion device to a reference opening degree, and fully close an other one of the refrigerant circuit shutoff device and the first expansion device not set to the reference opening degree. [Claim 6] The air-conditioning apparatus of claim 4 or 5, comprising: a bypass causing the high-pressure refrigerant to branch from a pipe between the refrigerant circuit shutoff device and the first expansion device and flow into a pipe having the low-pressure refrigerant flowing therethrough between the second heat exchanger and a low-pressure side of the compressor; and a bypass opening and closing device provided in the bypass to stop a flow of the high-pressure refrigerant, wherein the controller is configured to, in the cooling operation mode, fully close the bypass opening and closing device after lapse of a second reference time. [Claim 7] The air-conditioning apparatus of claim 6, wherein the bypass opening and closing device has a changeable opening area, and wherein, the controller is configured to set, during the cooling operation mode, set the bypass opening and closing device to a reference opening degree. [Claim 8] The air-conditioning apparatus of any one of claims 1 to 7, comprising: an outdoor unit housing the compressor, the refrigerant flow switching device, and the first heat exchanger; and an indoor unit housing the first expansion device and the second heat exchanger. [Claim 9] The air-conditioning apparatus of claim 8, wherein at least one of the refrigerant circuit shutoff device is provided on a pipe connecting the outdoor unit and the indoor unit or on a pipe included in the outdoor unit. [Claim 10] The air-conditioning apparatus of any one of claims 1 to 9, comprising a first fan configured to blow air to the first heat exchanger, wherein the controller is configured to operate, when the first fan is not operating, the first fan, and when the first fan is operating, keep the first fan operating. [Claim 11] The air-conditioning apparatus of any one of claims 1 to 10, comprising a second fan configured to blow air to the second heat exchanger, wherein the controller is configured to, when the second fan is not operating, operate the second fan, and when the second fan is operating, keep the second fan operating. [Claim 12] The air-conditioning apparatus of any one of claims 1 to 11, wherein the controller is configured to, when the refrigerant leaks, issue a warning by performing at least one of sounding of an alarm and displaying of an alarm. [Claim 13] The air-conditioning apparatus of any one of claims 9 to 12, wherein the outdoor unit comprises a plurality of outdoor units.