Air-conditioning apparatus with regulation of injection flow rate

Patent metadata

Field	Value
Publication number	US-9797610-B2
Application number	US-201114238541-A
Country	US
Kind code	B2
Filing date	Nov 7, 2011
Priority date	Nov 7, 2011
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

An air-conditioning apparatus includes a suction-injection pipe that introduces a refrigerant in a liquid or two-phase state into a suction side of a compressor, an expansion device that is arranged at the suction-injection pipe, and a controller that regulates the suction-injection flow rate of a refrigerant introduced into the suction side of the compressor through the suction-injection pipe by controlling the opening degree of the expansion device.

First claim

The invention claimed is:

1. An air-conditioning apparatus having a refrigeration cycle including a compressor, a first heat exchanger, a first expansion device, and a plurality of second heat exchangers that are connected by pipes, the air-conditioning apparatus comprising:
a suction-injection pipe configured to introduce, into a suction side of the compressor, injection refrigerant that is drawn from a refrigerant flow passage through which refrigerant that transfers heat in the first heat exchanger or the second heat exchangers circulates, wherein the injection refrigerant is in a liquid or a two-phase state;
a second expansion device arranged at the suction-injection pipe;
a controller configured to regulate, by controlling an opening degree of the second expansion device, a suction-injection flow rate of the injection refrigerant into the suction side of the compressor through the suction-injection pipe;
a first branching unit configured to draw refrigerant from the refrigerant flow passage in a case in which the refrigerant flows from the first heat exchanger to the first expansion device;
a second branching unit configured to draw refrigerant from the refrigerant flow passage in a case in which the refrigerant flows from the first expansion device to the first heat exchanger;
a branch pipe configured to connect the first branching unit with the second branching unit, wherein the branch pipe is connected to the suction-injection pipe at a connection portion;
a first conduction device arranged between the first branching unit and the connection portion; and
a second conduction device arranged between the second branching unit and the connection portion.

2. The air-conditioning apparatus of claim 1 , further comprising:
a refrigerant flow switching device configured to perform switching of the refrigerant flow passage, depending on whether a high-pressure refrigerant flows in the first heat exchanger, in which case the first heat exchanger functions as a condenser, or a low-pressure refrigerant flows in the first heat exchanger, in which case the first heat exchanger functions as an evaporator; and
a third expansion device configured to generate, in the case in which the first heat exchanger functions as an evaporator, a medium pressure refrigerant, a pressure of which is lower than a relatively high pressure refrigerant that is inside the second heat exchangers in a case in which the second heat exchangers function as condensers and that is higher than a relatively low pressure refrigerant that is inside the first heat exchanger in the case in which the first heat exchanger functions as the evaporator,
wherein the controller
allows, in the case in which the first heat exchanger functions as a condenser, relatively high-pressure refrigerant to flow through the suction-injection pipe, and
allows, in the case in which the first heat exchanger functions as an evaporator, the medium pressure refrigerant generated by the third expansion device to flow through the suction-injection pipe.

3. The air-conditioning apparatus of claim 2 ,
wherein, in the case in which the first heat exchanger functions as a condenser, refrigerant is caused to circulate between the first heat exchanger and the second heat exchangers without causing the refrigerant to pass through the third expansion device, and
wherein, in the case in which the first heat exchanger functions as an evaporator, the refrigerant is caused to pass through the second heat exchangers and then the third expansion device and then to flow into the first heat exchanger.

4. The air-conditioning apparatus of claim 2 , wherein the third expansion device includes, at a portion of a flow passage that is on an entry side of an expansion part and that is adjacent to the expansion part, a mixing device configured to mix a two-phase gas-liquid refrigerant that has flowed into the third expansion device.

5. The air-conditioning apparatus of claim 1 , wherein
the first conduction device is an opening/closing device configured to open and close the refrigerant flow passage of the branch pipe, and
the second conduction device is a backflow prevention device configured to flow a refrigerant only in a direction from the second branching unit to the suction-injection pipe.

6. The air-conditioning apparatus of claim 1 , wherein the first branching unit is a gas-liquid separator configured to deliver refrigerant that is mainly in a liquid state to the branch pipe.

7. The air-conditioning apparatus of claim 6 , wherein the gas-liquid separator has a structure in which
a length in an in-flow direction, in which the refrigerant flows into the gas-liquid separator, is greater than a length in a direction perpendicular to the in-flow direction,
an inlet pipe, from which refrigerant flows into the gas-liquid separator, and an outlet pipe, through which a majority of the refrigerant flows out of the gas-liquid separator, extend in a direction in which the refrigerant flows into the gas-liquid separator, and
the branch pipe is connected to a lower portion of the gas-liquid separator that is lower than a central portion in a height direction of the gas-liquid separator, and the branch pipe is configured to extract part of the refrigerant in the liquid state from inside of the gas-liquid separator to outside of the gas-liquid separator.

8. The air-conditioning apparatus of claim 1 , wherein the second branching unit is a gas-liquid separator configured to deliver refrigerant that is mainly in a liquid state to the branch pipe.

9. The air-conditioning apparatus of claim 1 , further comprising a discharged refrigerant temperature detection device for detecting temperature of refrigerant discharged from the compressor, wherein the controller regulates an opening area of the second expansion device in such a manner that the temperature of the discharged refrigerant detected by the discharged refrigerant temperature detection device becomes closer to a target temperature, does not exceed the target temperature, or falls within a target temperature range.

10. The air-conditioning apparatus of claim 1 , further comprising:
a discharged refrigerant temperature detection device for detecting temperature of a refrigerant discharged from the compressor; and
a high-pressure detection device for detecting pressure of the refrigerant discharged from the compressor,
wherein the controller regulates an opening area of the second expansion device in such a manner that a discharge degree of superheat calculated from the temperature of the discharged refrigerant detected by the discharged refrigerant temperature detection device and the refrigerant pressure detected by the high-pressure detection device becomes closer to a target degree of superheat, does not exceed the target degree of superheat, or falls within a target degree range of superheat.

11. The air-conditioning apparatus of claim 1 , further comprising a medium pressure detection device for detecting medium pressure or saturation temperature at the medium pressure, the medium pressure detection device being arranged at the refrigerant flow passage between the second branching unit and the third expansion device, wherein, in a state in which the first heat exchanger functions as an evaporator, the controller regulates an opening area of the third expansion device in such a manner that the medium pressure or the saturation temperature at the medium pressure detected by the medium pressure detection device becomes closer to a target value or falls within a target range.

12. The air-conditioning apparatus of claim 1 , wherein
a refrigerant-refrigerant heat exchanger is arranged at a portion of t

Assignees

• Yamashita Koji
• Hatomura Takeshi
• Ishimura Katsuhiro
• Mitsubishi Electric Corp

Inventors

• Yamashita Koji
• Hatomura Takeshi
• Ishimura Katsuhiro

Classifications

• F25B2313/0312

  Pressure sensors near the indoor heat exchanger · CPC title

• F25B2313/0231

  with simultaneous cooling and heating · CPC title

• F25B2500/19

  Calculation of parameters · CPC title

• F25B2313/003

  Indoor unit with water as a heat sink or heat source · CPC title

• F25B25/005

  using primary and secondary systems · CPC title