GB2564367A

GB2564367A - Air-conditioning device

Info

Publication number: GB2564367A
Application number: GB1817686.7A
Authority: GB
Inventors: Kimura Takanao
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-06-08
Filing date: 2016-06-08
Publication date: 2019-01-09
Anticipated expiration: 2036-06-08
Also published as: GB2564367A8; JP6570745B2; GB201817686D0; GB2564367B; WO2017212599A1; JPWO2017212599A1

Abstract

This air-conditioning device comprises: a heat source unit which has a compressor, a first flow path switching device, and a heat-source-side heat exchanger; indoor units which each have a throttle device and a use-side heat exchanger; a liquid pipe and a gas pipe which connect the heat source unit and the indoor units; a refrigerant circuit which is configured from the compressor, the first flow path switching device, the heat-source side heat exchanger, the throttle device, and the use-side heat exchanger connected by pipes through which a refrigerant is circulated; a first bypass pipe which connects the liquid pipe and the gas pipe; a second bypass pipe which branches off from the first bypass pipe and discharges the refrigerant to the exterior; a second flow rate switching device which opens and closes the heat-source-unit-side of the liquid pipe, the indoor-unit-side of the liquid pipe, and the first bypass pipe side; a first opening-closing device which is provided in the gas pipe; a second opening-closing device which is provided in the second bypass pipe; a refrigerant leakage detector which detects the leakage of the refrigerant from the refrigerant circuit; and a control device which, upon detecting leakage of the refrigerant during a cooling operation, closes the second opening-closing device and starts a pump down operation. After the completion of the pump down operation, the control device closes the first opening-closing device, and, upon detecting leakage of the refrigerant, opens the second opening-closing device.

Description

DESCRIPTION

Title of Invention

AIR-CONDITIONING APPARATUS

Technical Field [0001]

The present invention relates to an air-conditioning apparatus and in particular relates to control at the time of refrigerant leakage.

Background Art [0002]

A traditional air-conditioning apparatus includes a refrigerant circuit in which a compressor, a four-way valve, a heat source side heat exchanger, a use side expansion device, and a use side heat exchanger are sequentially interconnected by pipes in such a manner that refrigerant circulates in the refrigerant circuit, and is configured by interconnecting a heat source unit and an indoor unit by a gas pipe and a liquid pipe, the heat source unit including the compressor and the heat source side heat exchanger, the indoor unit including an expansion device and the use side heat exchanger. In an air-conditioning apparatus of this type, when refrigerant leakage occurs in the indoor unit, to prevent lack of oxygen in the indoor space, a pump-down operation is performed to collect the refrigerant in the indoor unit and the pipes into the heat source unit (for example, see Patent Literature 1).

[0003]

In the air-conditioning apparatus of Patent Literature 1, an open-close valve is provided in a liquid pipe between the heat source side heat exchanger and the use side expansion device and, when refrigerant leakage is detected by a gas detector, the four-way valve is controlled such a manner that an operation is switched to a cooling operation, the use side expansion device is fully opened, and the compressor is activated in a state where the open-close valve is closed to thereby perform the pump-down operation. In addition, after the end of the pump-down operation, the pipes constituting parts of the refrigerant circuit are removed and work such as troubleshooting will be performed.

Citation List

Patent Literature [0004]

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2002-228281

Summary of Invention

Technical Problem [0005]

A traditional air-conditioning apparatus such as that of Patent Literature 1 cannot collect all of the refrigerant residing in the indoor unit and pipes in the refrigerant circuit into the heat source unit though the refrigerant collection by the pump-down operation. Consequently, the problem is that the refrigerant remaining in the pipes after the end of the pump-down operation may flow out into the indoor. [0006]

The present invention has been made to solve the above-described problem, and an object of the present invention is to provide an air-conditioning apparatus that is capable of reducing the amount of refrigerant leakage into the indoor space at the time of refrigerant leakage.

Solution to Problem [0007]

An air-conditioning apparatus according to an embodiment of the present invention includes a heat source unit including a compressor, a first flow path switching device, and a heat source side heat exchanger; an indoor unit including an expansion device and a use side heat exchanger; a liquid pipe and a gas pipe each interconnecting the heat source unit and the indoor unit; a refrigerant circuit in which the compressor, the first flow path switching device, the heat source side heat exchanger, the expansion device, and the use side heat exchanger are interconnected by a pipe in such a manner that refrigerant circulates in the refrigerant circuit; a first bypass pipe interconnecting the liquid pipe and the gas pipe; a second bypass pipe branching from the first bypass pipe and configured to discharge the refrigerant to an outdoor space; a second flow path switching device configured to separately open and close a section connected to a portion of the liquid pipe connected to the heat source unit, a section connected to a portion of the liquid pipe connected to the indoor unit, and a section connected to the first bypass pipe; a first open-close device provided in the gas pipe; a second open-close device provided in the second bypass pipe; a refrigerant leakage detector configured to detect refrigerant leakage from the refrigerant circuit; and a controller configured to close the second open-close device to start a pump-down operation when refrigerant leakage is detected during a cooling operation, close the first open-close device after completion of the pump-down operation, and open the second open-close device when refrigerant leakage is detected.

Advantageous Effects of Invention [0008]

In the air-conditioning apparatus according to an embodiment of the present invention, when refrigerant leakage is detected even after the end of the pump-down operation, the second open-close device is opened to discharge the refrigerant remaining in the indoor unit and the pipes in the refrigerant circuit to the outdoor space via the second bypass pipe. With this operation, it is made possible to reduce the amount of refrigerant leakage into the indoor space at the time of refrigerant leakage.

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

[Fig. 2] Fig. 2 is a functional block diagram 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 at the time of a cooling operation of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 4] Fig. 4 is a refrigerant circuit diagram illustrating a flow of refrigerant at the time of a heating operation of the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 5] Fig. 5 is a flowchart illustrating the operation at the time of detection of refrigerant leakage in the air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 6] Fig. 6 is a schematic diagram illustrating a state of the refrigerant circuit in step S6 of the flowchart illustrated in Fig. 5.

[Fig. 7] Fig. 7 is a schematic diagram illustrating a state of the refrigerant circuit in step S9 of the flowchart illustrated in Fig. 5.

[Fig. 8] Fig. 8 is a schematic diagram illustrating a state of the refrigerant circuit in step S12 of the flowchart illustrated in Fig. 5.

[Fig. 9] Fig. 9 is a schematic diagram illustrating a state of the refrigerant circuit in step S14 of the flowchart illustrated in Fig. 5.

[Fig. 10] Fig. 10 is a functional block diagram of an air-conditioning apparatus according to Embodiment 2 of the present invention.

[Fig. 11] Fig. 11 is a flowchart illustrating the operation at the time of detection of refrigerant leakage in the air-conditioning apparatus according to Embodiment 2 of the present invention.

Description of Embodiments [0010]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described below. The size relationships of the components in the following figures may be different from the actual ones.

[0011]

Embodiment 1

Fig. 1 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 1 of the present invention.

The features of the air-conditioning apparatus according to Embodiment 1 of the present invention will be described below with reference to Fig. 1.

As illustrated in Fig. 1, the air-conditioning apparatus according to Embodiment 1 includes a heat source unit 10 and a plurality of indoor units 20. The indoor units 20 are connected in parallel to each other and connected to the heat source unit 10 via a liquid pipe 31 and a gas pipe 32.

The air-conditioning apparatus has a refrigerant circuit in which a compressor 11, a first flow path switching device 12, a heat source side heat exchanger 13, expansion devices 22, and use side heat exchangers 21 are sequentially connected by pipes in such a manner that refrigerant circulates in the refrigerant circuit. The air-conditioning apparatus is capable of performing a cooling operation or a heating operation by circulation of the refrigerant in the refrigerant circuit.

[0012]

It should be noted that although Embodiment 1 is described with an example in which two indoor units 20 are connected to one heat source unit 10, the number of the heat source units 10 may be two or more. Likewise, the number of the indoor units 20 may be one or three or more.

[0013]

The heat source unit 10 includes the compressor 11, the first flow path switching device 12, and the heat source side heat exchanger 13 and has a function of supplying heating energy or cooling energy to the indoor units 20.

The compressor 11 is configured to compress the suctioned refrigerant into a state of high temperature and high pressure. The first flow path switching device 12 is configured to switch the flows of the refrigerant between the cooling operation and the heating operation. It should be noted that while the first flow path switching device 12 is described with an example as a four-way valve, the first flow path switching device 12 may be configured by combining a two-way valve, a three-way valve, or other valves. The heat source side heat exchanger 13 is configured to act as a condenser or a radiator in the cooling operation and as an evaporator in the heating operation, and exchange heat between the air supplied from a fan (not shown) and the refrigerant.

[0014]

Further, the heat source unit 10 further includes a controller 50, a discharge pressure sensor 61, and a suction pressure sensor 62. The controller 50 will be described later.

The discharge pressure sensor 61 is provided to a pipe interconnecting the first flow path switching device 12 and a discharge section of the compressor 11 and configured to measure a discharge pressure of the compressor 11. The discharge pressure sensor 61 is, for example, a pressure sensor and is configured to output to the controller 50 a signal indicative of the discharge pressure that has been measured.

[0015]

It should be noted that the discharge pressure sensor 61 may include a storage device or another similar device. In this case, the discharge pressure sensor 61 accumulates pieces of data of the measured discharge pressures for a predetermined period of time in the storage device or another similar device and outputs signals of the measured discharge pressures to the controller 50 at predetermined intervals. [0016]

The suction pressure sensor 62 is provided to a pipe interconnecting the first flow path switching device 12 and the suction section of the compressor 11 and is configured to measure a suction pressure of the compressor 11. The suction pressure sensor 62 is, for example, a pressure sensor and is configured to output to the controller 50 a signal indicative of the suction pressure that has been measured. [0017]

It should be noted that the suction pressure sensor 62 may include a storage device or another similar device. In this case, the suction pressure sensor 62 accumulates pieces of data of the measured suction pressures for a predetermined period of time in the storage device or another similar device and outputs signals of the measured suction pressures to the controller 50 at predetermined intervals.

[0018]

The indoor units 20 each include the use side heat exchanger 21 and the expansion device 22 and each have a function of cooling or heating an airconditioned space such as an indoor space by heating energy or cooling energy supplied from the heat source unit 10. The use side heat exchangers 21 are each configured to act as an evaporator at the time of the cooling operation and as a condenser or radiator at the time of the heating operation, and exchange heat between the refrigerant and the air. The expansion devices 22 are each configured to act as a pressure reducing valve or an expansion valve to depressurize and expand the refrigerant.

[0019]

In addition, a refrigerant leakage detector 63 is provided to a pipe branching from the liquid pipe 31 to each of the indoor units 20.

The refrigerant leakage detectors 63 are each a detection unit configured to detect refrigerant leakage and output a signal, such as a semiconductor type gas sensor that detects, as a refrigerant gas concentration in the air, a change in a resistance value generated when a metal oxide semiconductor comes into contact with refrigerant gas. It should be noted that the configuration of Embodiment 1 includes the refrigerant leakage detectors 63 each provided to a corresponding one of the indoor units 20 in one-to-one correspondence in such a manner that the specific channel of one of the indoor units 20 in which refrigerant leakage has occurred can be determined, but one single refrigerant leakage detector may be provided to the airconditioning apparatus. In such a configuration as well, it is still possible to determine whether or not refrigerant leakage has occurred in the air-conditioning apparatus.

[0020]

The liquid pipe 31 includes a second flow path switching device 33 and the gas pipe 32 includes a first open-close device 34.

Further, a bypass 40 is provided between the heat source unit 10 and the indoor units 20. The bypass 40 includes a first bypass pipe 41 interconnecting the liquid pipe 31 and the gas pipe 32, a second bypass pipe 42 branching from the first bypass pipe 41 and having an open end, and a second open-close device 43 provided in the second bypass pipe 42.

[0021]

The second flow path switching device 33 is configured to separately open and close a section connected to a portion of the liquid pipe 31 connected to the heat source unit 10, a section connected to a portion of the liquid pipe 31 connected to the indoor units 20, and a section connected to the first bypass pipe 41, and switch the flows of the refrigerant. It should be noted that the second flow path switching device 33 is described with an example as a three-way valve, the second flow path switching device 33 may be configured by combining two-way valves or other valves.

The first open-close device 34 and the second open-close device 43 are each opened and closed to enable or disable flow of the refrigerant.

[0022]

As illustrated in Fig. 1, the broken line 70 indicates the boundary between the outdoor space and the indoor space. The heat source unit 10 and the bypass 40 are placed in the outdoor space, whereas the indoor units 20 and the refrigerant leakage detectors 63 are placed in the indoor space.

It should be noted that the bypass 40 in Embodiment 1 is placed in the outdoor space, but Embodiment 1 is not limited to this arrangement and, as long as at least the open end of the second bypass pipe 42 is placed in the outdoor space, the remaining components and portions may be placed in the indoor space.

[0023]

Fig. 2 is a functional block diagram of the air-conditioning apparatus according to Embodiment 1 of the present invention.

The controller 50 of the air-conditioning apparatus according to Embodiment 1 includes a measurement unit 51, an arithmetic unit 52, a determination unit 53, and a driving unit 54. The controller 50 is configured to receive signals input from the discharge pressure sensor 61, the suction pressure sensor 62, and the refrigerant leakage detectors 63. The controller 50 is also configured to output signals to the second flow path switching device 33, the first open-close device 34, and the second open-close device 43.

[0024]

The measurement unit 51 is configured to acquire measurement signals of the discharge pressure sensor 61 and the suction pressure sensor 62 and detection signals of the refrigerant leakage detectors 63.

The arithmetic unit 52 is configured to process the measurement signals and the detection signals that the measurement unit 51 has acquired.

The determination unit 53 is configured to perform various determinations on the basis of a processing result of the arithmetic unit 52.

The driving unit 54 is configured to output driving signals to the second flow path switching device 33, the first open-close device 34, and the second open-close device 43 on the basis of a determination result of the determination unit 53 to drive the second flow path switching device 33, the first open-close device 34, and the second open-close device 43.

[0025]

Fig. 3 is a refrigerant circuit diagram illustrating a flow of the refrigerant at the time of a cooling operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. It should be noted that the refrigerant is indicated by a solid-line arrow and closed sections of the second flow path switching device 33, the first open-close device 34, and the second open-close device 43 are shown in black. Such an indication also applies to Figs. 4 and 6 to 9 as will be described later.

The flow of the refrigerant at the time of the cooling operation of the airconditioning apparatus according to Embodiment 1 will be described below with reference to Fig. 3.

[0026]

At the time of the cooling operation, the first flow path switching device 12 is made to switch the operation to the cooling operation. That is, switching is made in such a manner that the discharge section of the compressor 11 and the heat source side heat exchanger 13 are connected to each other, and the section of the second flow path switching device 33 connected to the first bypass pipe 41 and the first openclose device 34 are each closed.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 of the heat source unit 10 passes through the first flow path switching device 12, and is subjected to heat exchange with outdoor air blown by a fan (not shown) in the heat source side heat exchanger 13 to be condensed and liquefied. The refrigerant that has condensed and liquefied flows out of the heat source unit 10. The refrigerant flowing out of the heat source unit 10 passes through the liquid pipe 31 and the second flow path switching device 33, and then branches to flow into each of the indoor units 20.

[0027]

The refrigerant that has flowed into each of the indoor units 20 is depressurized to have a low pressure by a corresponding one of the expansion devices 22. The depressurized refrigerant is subjected to heat exchange with indoor air in the use side heat exchangers 21 to be evaporated and gasified. In addition, the refrigerant that has been brought into the gaseous state flows out of each of the indoor units 20 to converge at the gas pipe 32, passes through the first open-close device 34, and flows into the heat source unit 10. The refrigerant that has flowed into the heat source unit 10 passes through the first flow path switching device 12 to be suctioned into the compressor 11.

[0028]

Fig. 4 is a refrigerant circuit diagram illustrating a flow of the refrigerant at the time of a heating operation of the air-conditioning apparatus according to Embodiment 1 of the present invention.

The flow of the refrigerant at the time of the heating operation of the airconditioning apparatus according to Embodiment 1 will be described below with reference to Fig. 4.

[0029]

At the time of the heating operation, the first flow path switching device 12 is made to switch the operation to the heating operation. That is, switching is made in such a manner that the suction section of the compressor 11 and the heat source side heat exchanger 13 are connected to each other, and the section of the second flow path switching device 33 connected to the first bypass pipe 41 and the first openclose device 34 are each closed.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 of the heat source unit 10 passes through the first flow path switching device 12, and flows out of the heat source unit 10. The refrigerant that has flowed out of the heat source unit 10 passes through the gas pipe 32 and the first open-close device 34, and then branches to flow into each of the indoor units 20.

[0030]

The refrigerant that has flowed into each of the indoor units 20 is subjected to heat exchange with indoor air in a corresponding one of the use side heat exchangers 21 to be condensed and liquefied. The refrigerant that has condensed and liquefied is depressurized to have a low pressure by a corresponding one of the expansion devices 22. The depressurized refrigerant flows out of each of the indoor units 20 to converge at the liquid pipe 31, passes through the second flow path switching device 33, and flows into the heat source unit 10. The refrigerant that has flowed into the heat source unit 10 is subjected to heat exchange with the outdoor air blown by a fan (not shown) in the heat source side heat exchanger 13 to be evaporated and gasified. The gasified refrigerant passes through the first flow path switching device 12 to be suctioned by the compressor 11.

[0031]

Fig. 5 is a flowchart illustrating the operation at the time of detection of refrigerant leakage in the air-conditioning apparatus according to Embodiment 1 of the present invention, Fig. 6 is a schematic diagram illustrating a state of the refrigerant circuit in step S6 of the flowchart illustrated in Fig. 5, Fig. 7 is a schematic diagram illustrating a state of the refrigerant circuit in step S9 of the flowchart illustrated in Fig. 5, Fig. 8 is a schematic diagram illustrating a state of the refrigerant circuit in step S12 of the flowchart illustrated in Fig. 5, and Fig. 9 is a schematic diagram illustrating a state of the refrigerant circuit in step S14 of the flowchart illustrated in Fig. 5.

[0032]

The operation at the time of detection of refrigerant leakage in the airconditioning apparatus according to Embodiment 1 will be described below with reference to Figs. 5 to 9.

The determination unit 53 determines whether or not refrigerant leakage has occurred on the basis of detection results of the refrigerant leakage detectors 63 (step S1).

[0033]

When the determination unit 53 determines that no refrigerant leakage has occurred (NO in step S1), the process returns to step S1.

Meanwhile, when the determination unit 53 determines that refrigerant leakage has occurred (YES in step S1), the determination unit 53 determines whether or not the current operation is the cooling operation (step S2).

[0034]

When the determination unit 53 determines that the current operation is the cooling operation (YES in step S2), the driving unit 54 switches settings of the second flow path switching device 33 (step S9) and starts a pump-down operation (step S10).

Meanwhile, when the determination unit 53 determines that the current operation is not the cooling operation, in other words, the current operation is the heating operation (NO in step S2), the driving unit 54 causes the first flow path switching device 12 to switch the operation to the cooling operation and stops the compressor 11 (step S3). The reason why the compressor 11 is stopped in step S3 is that, when the current operation is the heating operation, the flow of the refrigerant is inverted compared with the cooling operation, and it is necessary to stop the compressor 11 once to switch the operation to the cooling operation.

[0035]

After step S3, on basis of pressures indicated by the measurement signals of the discharge pressure sensor 61 and the suction pressure sensor 62 acquired by the measurement unit 51, the arithmetic unit 52 obtains the pressure difference ΔΡ (= discharge pressure - suction pressure) between the pressures. In addition, the determination unit 53 determines whether or not the pressure difference ΔΡ is a value smaller than the reference pressure difference P1 (step S4). Here, the reference pressure difference P1 is a pressure difference with which the compressor 11 can be operated without malfunctioning, and the reference pressure difference P1 is 0, for example. The reference pressure difference P1 is stored in advance in the storage device included in the arithmetic unit 52 or another storage device different from that of the arithmetic unit 52 (both of which are not shown). Once the compressor 11 stops, the air-conditioning apparatus is typically prohibited from restarting the compressor 11 for a predetermined period of time, for example, three minutes to wait for pressure equalization in the refrigeration circuit in such a manner that the compressor 11 is not damaged.

[0036]

In step S4, when the determination unit 53 determines that the pressure difference ΔΡ is a value smaller than the reference pressure difference P1 (YES in step S4), the driving unit 54 causes the compressor 11 to operate (step S5).

Meanwhile, when the determination unit 53 determines that the pressure difference ΔΡ is not a value smaller than the reference pressure difference P1 (NO in step S4), the driving unit 54 switches, as illustrated in Fig. 6, the settings of the second flow path switching device 33 and opens the second open-close device 43 (step S6). In other words, by opening the section of the second flow path switching device 33 connected to the first bypass pipe 41, the liquid pipe 31 and the gas pipe 32 are brought into communication and the pressure equalization is promoted. Further, by opening the second open-close device 43, the refrigerant in the refrigerant circuit is discharged to the outdoor space via the second bypass pipe 42 to reduce the amount of refrigerant leakage from the leakage point 71.

[0037]

After step S6, when the determination unit 53 determines that the pressure difference ΔΡ is not a value smaller than the reference pressure difference P1 (NO in step S7), the process returns to step S7.

Meanwhile, when the determination unit 53 determines that the pressure difference ΔΡ is a value smaller than the reference pressure difference P1 (YES in step S7), the driving unit 54 closes the second open-close device 43 (step S8) and causes the compressor 11 to operate (step S5).

[0038]

After step S5, the driving unit 54 switches the settings of the second flow path switching device 33 (step S9) and starts the pump-down operation (step S10). At this point, as illustrated in Fig. 7, the section of the second flow path switching device 33 connected to the heat source unit 10 is closed so that the refrigerant does not flow from the heat source unit 10 into the indoor units 20. Meanwhile, the refrigerant is allowed to flow from the indoor units 20 to the heat source unit 10, and the refrigerant residing in the indoor units 20 and the pipes in the refrigerant circuit are collected into the heat source unit 10.

[0039]

After step S10, the determination unit 53 determines whether or not collection of the refrigerant is completed (step S11). It should be noted that, with regard to the determination on the collection of the refrigerant, for example, a liquid surface determination unit (not shown) may be provided to the heat source unit 10 to determine the completion of collection in response to a predetermined quantity having been exceeded. Alternatively, when the refrigerant is collected as liquid refrigerant, the gas refrigerant is suctioned from the suction section of the compressor 11, and thus the suction pressure is decreased. This pressure having decreased may be measured by the suction pressure sensor 62 to determine that the collection is completed when a predetermined pressure, for example, a pressure less than 1 kg/cm² is reached.

[0040]

In step S11, when the determination unit 53 determines that the collection of the refrigerant is not completed (NO in step S11), the process returns to step S11.

Meanwhile, when the determination unit 53 determines that the collection of the refrigerant is completed (YES in step S11), the driving unit 54 ends the pump-down operation and, as illustrated in Fig. 8, closes the first open-close device 34 (step S12). With this operation, the refrigerant is contained in the heat source unit 10. [0041]

After step S12, on the basis of the processing result of the arithmetic unit 52 on the detection signals of the refrigerant leakage detectors 63, the determination unit 53 determines whether or not refrigerant leakage has occurred (step S13).

When the determination unit 53 determines that refrigerant leakage has occurred (YES in step S13), the driving unit 54 opens, as illustrated in Fig. 9, the second open-close device 43 (step S14), and the process returns to step S13. In this manner, when refrigerant leakage is detected even after the end of the pumpdown operation, the second open-close device 43 is opened and thereby the refrigerant is discharged to the outdoor space via the second bypass pipe 42. At this point, the amount of refrigerant discharge from the second bypass pipe 42 is much larger than the amount of refrigerant leakage from the leakage point 71, and the refrigerant is drawn toward the second bypass pipe 42, so that the amount of refrigerant leakage from the leakage point 71 into the indoor space can be reduced. [0042]

Meanwhile, when the determination unit 53 determines that no refrigerant leakage has occurred (NO in step S13), the driving unit 54 closes the second openclose device 43 (step S15), and the process returns to step S13. In other words, the refrigerant circuit is brought into the state illustrated in Fig. 8.

[0043]

Subsequently, the driving unit 54, in response to a state of the occurrence of refrigerant leakage, opens the second open-close device 43 (step S14), or closes the second open-close device 43 (step S15).

[0044]

As described above, in the air-conditioning apparatus according to Embodiment 1, when refrigerant leakage is detected even after the end of the pumpdown operation, the second open-close device 43 is opened and thereby the refrigerant remaining in the indoor units 20 and the pipes in the refrigerant circuit are discharged to the outdoor space via the second bypass pipe 42. With this operation, it is made possible to reduce the amount of refrigerant leakage into the indoor space at the time of refrigerant leakage.

[0045]

Besides, as the pump-down operation is traditionally performed in the cooling operation, the problem is that when refrigerant leakage has occurred during the heating operation, switching the heating operation to the cooling operation requires time, causing increase in the amount of refrigerant leakage.

In view of the above, in the air-conditioning apparatus according to Embodiment 1, when refrigerant leakage is detected during the heating operation, the section of the second flow path switching device 33 connected to the first bypass pipe 41 is opened. With this operation, it is made possible to bring the liquid pipe 31 and the gas pipe 32 into communication with each other, promote pressure equalization of the refrigerant, shorten the time required in switching the heating operation to the cooling operation, and reduce the amount of refrigerant leakage into the indoor space.

[0046]

Embodiment 2

Embodiment 2 of the present invention will be described below. Explanations of the same components as those of Embodiment 1 will be omitted and the same reference signs are assigned to the same components as those of Embodiment 1 or equivalent components to those of Embodiment 1.

[0047]

Fig. 10 is a functional block diagram of an air-conditioning apparatus according to Embodiment 2 of the present invention.

The air-conditioning apparatus according to Embodiment 2 includes a second controller 80 as a controller different from the controller 50 provided in the heat source unit 10 as illustrated in Fig. 10.

The second controller 80 includes a second measurement unit 81, a second arithmetic unit 82, a second determination unit 83, and a second driving unit 84. The controller 50 is configured to receive signals input from the discharge pressure sensor 61 and the suction pressure sensor 62, and the second controller 80 is configured to receive signals input from the refrigerant leakage detectors 63. The second controller 80 is also configured to output signals to the second flow path switching device 33, the first open-close device 34, and the second open-close device 43. [0048]

The second measurement unit 81 is configured to acquire detection signals from refrigerant leakage detectors 63.

The second arithmetic unit 82 is configured to process the detection signals that the second measurement unit 81 has acquired.

The second determination unit 83 is configured to perform various determinations on the basis of a processing result of the second arithmetic unit 82.

The second driving unit 84 is configured to output driving signals to the second flow path switching device 33, the first open-close device 34, and the second openclose device 43 on the basis of a determination result of the second determination unit 83 to drive the second flow path switching device 33, the first open-close device 34, and the second open-close device 43.

[0049]

Besides, the second controller 80 is capable of bidirectionally communicating with the controller 50. Consequently, the second controller 80 is capable of driving the second flow path switching device 33, the first open-close device 34, and the second open-close device 43 on the basis of a processing result of the controller 50. For example, the second controller 80 may be configured in such a manner that the second driving unit 84 drives the second flow path switching device 33, the first open close device 34, and the second open-close device 43 on the basis of the driving signals of the driving unit 54.

[0050]

The power supply system of the second controller 80 is, for example, a private power generator, and is a power supply system different from that of the heat source unit 10. Consequently, even when the heat source unit 10 cannot operate due to power outage, failure, or other malfunction, the air-conditioning apparatus according to Embodiment 2 can drive the second flow path switching device 33, the first openclose device 34, and the second open-close device 43. In addition, by driving the second flow path switching device 33, the first open-close device 34, and the second open-close device 43, even when the heat source unit 10 cannot operate due to power outage, failure, or other malfunction, the refrigerant in the refrigerant circuit can be discharged to the outdoor space via the second bypass pipe 42.

[0051]

Fig. 11 is a flowchart illustrating the operation at the time of detection of refrigerant leakage in the air-conditioning apparatus according to Embodiment 2 of the present invention.

The operation at the time of detection of refrigerant leakage in the airconditioning apparatus according to Embodiment 2 will be described below with reference to Fig. 11.

The second determination unit 83 determines whether or not refrigerant leakage has occurred on the basis of the detection results of the refrigerant leakage detectors 63 (step S21).

[0052]

When the second determination unit 83 determines that no refrigerant leakage has occurred (NO in step S21), the process returns to step S21.

Meanwhile, when the second determination unit 83 determines that refrigerant leakage has occurred (YES in step S21), the second determination unit 83 determines whether or not the heat source unit 10 is operational (step S22). It should be noted that the second determination unit 83 performs the determination, for example, on the basis of the signal regarding the state of the heat source unit 10 received from the controller 50.

[0053]

When the second determination unit 83 determines that the heat source unit 10 is operational (YES in step S22), the process goes to step S2 of Fig. 5. It should be noted that step S2 and the subsequent steps of Fig. 5 are the same as or similar to those described in Embodiment 1, and thus explanations of these steps are accordingly omitted.

Meanwhile, when the determination unit 53 determines that the heat source unit 10 is not operational (NO in step S22), the second driving unit 84 switches the settings of the second flow path switching device 33 in such a manner that the section of the second flow path switching device 33 connected to the heat source unit 10 is closed, closes the first open-close device 34, and opens the second open-close device 43. In other words, by controlling the second flow path switching device 33, the first open-close device 34, and the second open-close device 43 as illustrated in Fig. 9, the refrigerant is discharged to the outdoor space via the second bypass pipe

42.

[0054]

As described above, in the air-conditioning apparatus according to Embodiment 2, the second controller 80 has a power supply system different from that of the heat source unit 10. Consequently, even when the heat source unit 10 cannot operate due to power outage, failure, or other malfunction, the refrigerant residing in the refrigerant circuit can be discharged to the outdoor space via the second bypass pipe 42 by the second controller 80 driving the second flow path switching device 33, the first open-close device 34, and the second open-close device

43. With this operation, even when the heat source unit 10 cannot operate, the amount of refrigerant leakage into the indoor space at the time of refrigerant leakage can be reduced.

Reference Signs List [0055] heat source unit 11 compressor 12 first flow path switching device heat source side heat exchanger 20 indoor unit use side heat exchanger 22 expansion device 31 liquid pipe gas pipe second flow path switching device 34 first open-close device bypass 41 first bypass pipe second bypass pipe 43 second open-close device 50 controller measurement unit 52 arithmetic unit 53 determination unit 54 driving unit 61 discharge pressure sensor 62 suction pressure sensor refrigerant leakage detector broken line leakage point 80 second controller second measurement unit 82 second arithmetic unit second determination unit second driving unit

Claims

CLAIMS [Claim 1]

An air-conditioning apparatus comprising:

a heat source unit including a compressor, a first flow path switching device, and a heat source side heat exchanger;

an indoor unit including an expansion device and a use side heat exchanger;

a liquid pipe and a gas pipe each interconnecting the heat source unit and the indoor unit;

a refrigerant circuit in which the compressor, the first flow path switching device, the heat source side heat exchanger, the expansion device, and the use side heat exchanger are interconnected by a pipe in such a manner that refrigerant circulates in the refrigerant circuit;

a first bypass pipe interconnecting the liquid pipe and the gas pipe;

a second bypass pipe branching from the first bypass pipe and configured to discharge the refrigerant to an outdoor space;

a second flow path switching device configured to separately open and close a section connected to a portion of the liquid pipe connected to the heat source unit, a section connected to a portion of the liquid pipe connected to the indoor unit, and a section connected to the first bypass pipe;

a first open-close device provided in the gas pipe;

a second open-close device provided in the second bypass pipe;

a refrigerant leakage detector configured to detect refrigerant leakage from the refrigerant circuit; and a controller configured to close the second open-close device to start a pumpdown operation when refrigerant leakage is detected during a cooling operation, close the first open-close device after completion of the pump-down operation, and open the second open-close device when refrigerant leakage is detected.
[Claim 2]

The air-conditioning apparatus of claim 1, wherein the controller includes a measurement unit configured to acquire a detection signal of the refrigerant leakage detector, an arithmetic unit configured to process the detection signal acquired by the measurement unit, a determination unit configured to determine whether or not refrigerant leakage occurs on a basis of a processing result of the arithmetic unit, and a driving unit configured to close the second open-close device to start the pump-down operation when the determination unit determines that refrigerant leakage occurs during the cooling operation, close the first open-close device after completion of the pump-down operation, and open the second open-close device when the determination unit determines that refrigerant leakage occurs.
[Claim 3]

The air-conditioning apparatus of claim 2, wherein the driving unit is configured to switch an operation to the cooling operation when the determination unit determines that refrigerant leakage occurs during a heating operation, open the section of the second flow path switching device connected to the first bypass pipe, and open the second open-close device.
[Claim 4]

The air-conditioning apparatus of claim 3, further comprising:

a discharge pressure sensor configured to measure a pressure in a discharge section of the compressor; and a suction pressure sensor configured to measure a pressure in a suction section of the compressor, wherein after the section of the second flow path switching device connected to the first bypass pipe is opened and the second open-close device is opened, the arithmetic unit is configured to obtain, on a basis of pressures indicated by measurement signals of the discharge pressure sensor and the suction pressure sensor acquired by the measurement unit, a pressure difference ΔΡ between the pressures indicated by the measurement signals, and the driving unit is configured to, when the determination unit determines that the pressure difference ΔΡ is a value smaller than a reference pressure difference P1, close the section of the second flow path switching device connected to the portion of the liquid pipe connected to the indoor unit, close the second open-close device, and start the pump-down operation.
[Claim 5]

The air-conditioning apparatus of any one of claims 1 to 4, further comprising a second controller including a power supply system different from a power supply system of the heat source unit, wherein the second controller is configured to close the section of the second flow path switching device connected to the heat source unit, close the first open-close device, and open the second open-close device when the heat source unit is not operational. [Claim 6]

The air-conditioning apparatus of claim 5, wherein the second controller includes a second measurement unit configured to acquire a detection signal of the refrigerant leakage detector, a second arithmetic unit configured to process the detection signal acquired by the second measurement unit, a second determination unit configured to determine whether or not refrigerant leakage occurs on a basis of a processing result of the second arithmetic unit and whether or not the heat source unit is operational, and a second driving unit configured to, when the second determination unit determines that refrigerant leakage occurs and determines that the heat source unit is not operational, close the section of the second flow path switching device connected to the heat source unit, close the first open-close device, and open the second openclose device.