Air-conditioning apparatus

Patent metadata

Field	Value
Publication number	US-11274864-B2
Application number	US-201716639946-A
Country	US
Kind code	B2
Filing date	Oct 5, 2017
Priority date	Oct 5, 2017
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

An air-conditioning apparatus includes a refrigeration circuit, a first shut-off device, a leakage detection device, and a controller configured to perform a refrigerant recovery operation in a case where refrigerant leakage is detected. At the time of the refrigerant recovery operation, the controller performs control to perform a first operation of recovering refrigerant from a load-side heat exchanger into an accumulator and a heat-source-side heat exchanger, and a second operation of moving refrigerant in the heat-source-side heat exchanger to the accumulator. In the first operation, the first shut-off device is closed, a flow passage switching device is brought into a first connection state, and a compressor is driven. The second operation is performed after the first operation, and in the second operation, the connection state of the flow passage switching device is switched to a second connection state in a state where the compressor is being operated.

First claim

The invention claimed is:

1. An air-conditioning apparatus comprising:
a refrigeration circuit where a compressor, a flow passage switching device, a heat-source-side heat exchanger, an expansion device, a load-side heat exchanger, and an accumulator are connected by pipes, the compressor being configured to compress and discharge refrigerant, the flow passage switching device being provided on a discharge port of the compressor and configured to switch a flow of the refrigerant, the expansion device being configured to decompress the refrigerant, the load-side heat exchanger being configured to condition air inside a room, the accumulator being provided on a suction port of the compressor and configured to store liquid refrigerant;
a first shut-off device provided on a pipe connecting the heat-source-side heat exchanger and the expansion device;
a leakage detection device configured to detect refrigerant leakage inside the room; and
a controller configured to switch from a normal operation to a refrigerant recovery operation and perform the refrigerant recovery operation, in a case where refrigerant leakage is detected by the leakage detection device,
wherein the controller
controls switching of a connection state of the flow passage switching device between
a first connection state in which the discharge port of the compressor is connected to the heat-source-side heat exchanger, and the suction port of the compressor is connected to the load-side heat exchanger through the accumulator, and
a second connection state in which the discharge port of the compressor is connected to the load-side heat exchanger, and the suction port of the compressor is connected to the heat-source-side heat exchanger through the accumulator, and

performs control to perform, at the time of the refrigerant recovery operation,
a first operation of closing the first shut-off device, bringing the connection state of the flow passage switching device into the first connection state, and recovering the refrigerant from the load-side heat exchanger into the accumulator and the heat-source-side heat exchanger by driving of the compressor, and
a second operation, performed after the first operation, of switching the connection state of the flow passage switching device to the second connection state in a state where the compressor is being driven, and moving the refrigerant that is condensed at the heat-source-side heat exchanger to the accumulator.

2. The air-conditioning apparatus of claim 1 , wherein the controller performs control to increase an operating frequency of the compressor, before switching the connection state of the flow passage switching device to the second connection state at the time of the refrigerant recovery operation.

3. The air-conditioning apparatus of claim 2 , wherein the controller performs control to switch again to the first operation after the second operation is ended, and to reduce a frequency of the compressor at an end of the second operation.

4. The air-conditioning apparatus of claim 2 , further comprising a heat-source-side pressure detection device configured to detect a discharge pressure and a suction pressure of the compressor,
wherein the controller performs control to maintain a state where the compressor is accelerated, when the suction pressure detected by the heat-source-side pressure detection device is greater than the discharge pressure.

5. The air-conditioning apparatus of claim 4 , wherein
the controller includes a timer configured to measure a time from a switching operation of the flow passage switching device, and
the controller performs control to maintain the state where the compressor is accelerated, until the suction pressure that is detected by the heat-source-side pressure detection device becomes smaller than the discharge pressure, or until a measured time of the timer exceeds a set time that is set in advance.

6. The air-conditioning apparatus of claim 1 , wherein, at the time of the refrigerant recovery operation, the controller
controls to increase an opening degree of the expansion device after switching the connection state of the flow passage switching device to the first connection state, and
controls to reduce the opening degree of the expansion device before switching the connection state of the flow passage switching device to the second connection state.

7. The air-conditioning apparatus of claim 1 , further comprising:
a bypass pipe connecting the discharge port and the suction port of the compressor; and
a bypass valve provided on the bypass pipe, and configured to adjust an amount of refrigerant that flows through the bypass pipe,
wherein, at the time of the refrigerant recovery operation, the controller
controls to close the bypass valve before switching the connection state of the flow passage switching device to the first connection state, and at the time of stopping the compressor, and
controls to open the bypass valve before switching the connection state of the flow passage switching device to the second connection state.

8. The air-conditioning apparatus of claim 1 , wherein, at the time of the refrigerant recovery operation, the controller performs control to perform a third operation of stopping the compressor, after switching the connection state of the flow passage switching device to the second connection state.

9. The air-conditioning apparatus of claim 8 , wherein the controller performs control such that, after the second operation, an operation combining the first operation and the second operation that is performed after the first operation is performed one or plural times, and the first operation is then performed, and the third operation is then performed.

10. The air-conditioning apparatus of claim 1 , further comprising a valve provided between the flow passage switching device and the accumulator, the valve being configured to shut off a flow of refrigerant from the accumulator to the flow passage switching device,
wherein, at the time of the refrigerant recovery operation, the controller performs control to perform a third operation of stopping the compressor, after bringing the connection state of the flow passage switching device into the first connection state.

11. The air-conditioning apparatus of claim 1 , further comprising a second shut-off device provided between the compressor and the load-side heat exchanger.

12. The air-conditioning apparatus of claim 8 , further comprising a load-side pressure detection device configured to detect a pressure of the refrigerant at the load-side heat exchanger,
wherein the controller performs, after the third operation, control to perform the first operation again, in a case where the pressure detected by the load-side pressure detection device is at or greater than a load-side pressure threshold that is set in advance.

13. The air-conditioning apparatus of claim 1 , wherein the controller performs control in the normal operation such that the first operation is performed whenever operation is stopped.

14. The air-conditioning apparatus of claim 1 , further comprising:
a heat-source-side fan configured to supply air to the heat-source-side heat exchanger; and
a load-side fan configured to supply air to the load-side heat exchanger,
wherein, in the refrigerant recovery operation, the controller sets a maximum value of rotation speed of the heat-source-side fan, a maximum value of rotation speed of the load-side fan, and an upper limit value of an operating frequency of the compressor to be higher than at the time of the normal operation, and sets a lower limit value of the operating frequency of

Assignees

• Mitsubishi Electric Corp

Inventors

• Nishio Jun
• Ikeda Soshi
• Ishimura Katsuhiro
• Ogura Kohei
• Yamashita Koji

Classifications

• F25B13/00 Primary

  Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) · CPC title

• F25B2600/11

  Fan speed control · CPC title

• F25B49/02

  for compression type machines, plants or systems · CPC title

• F25B41/20

  Disposition of valves, e.g. of on-off valves or flow control valves (expansion valves F25B41/31) · CPC title

• F25B41/24

  Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part · CPC title