Air-conditioning apparatus

Patent metadata

Field	Value
Publication number	US-9759460-B2
Application number	US-201214236339-A
Country	US
Kind code	B2
Filing date	Aug 15, 2012
Priority date	Nov 7, 2011
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A channel on an upstream side of a third expansion device and a channel on an upstream side of a second expansion device are connected during a heating operation, and medium pressure refrigerant generated by the third expansion device during the heating operation is introduced on a suction side of a compressor via the second expansion device and a suction injection pipe.

First claim

The invention claimed is:

1. An air conditioning apparatus, wherein
a compressor including a compression chamber inside a hermetically sealed container thereof, a first refrigerant flow switching device, a first heat exchanger, at least one first expansion device, and at least one second heat exchanger are connected by refrigerant pipes to form a circuit constituting a refrigeration cycle,
the air-conditioning apparatus comprising an accumulator for accumulating excess refrigerant provided on a channel on a suction side of the compressor, a suction injection pipe for externally introducing refrigerant in a liquid or a two-phase state into a channel between the compressor and the accumulator, and a second expansion device provided to the suction injection pipe,
the air-conditioning apparatus being able to perform a heating operation, in which at least low pressure refrigerant flows into the first heat exchanger to cause it to serve as an evaporator, and high pressure refrigerant flows into some or all of the at least one second heat exchanger to cause them to serve as at least one condenser,
the air conditioning apparatus comprising a third expansion device that generates a medium pressure smaller than the high pressure and larger than the low pressure during the heating operation in a channel of refrigerant from the at least one second heat exchanger to the first heat exchanger during the heating operation, and
wherein a channel on an upstream side of the third expansion device and a channel on an upstream side of the second expansion device are connected during the heating operation, and the medium pressure refrigerant generated by the third expansion device during the heating operation is introduced on a suction side of the compressor via the second expansion device and the suction injection pipe.

2. The air conditioning apparatus of claim 1 , wherein
by action of the first refrigerant flow switching device, it is possible to switch between
cooling operation, in which high pressure refrigerant flows into the first heat exchanger to cause it to serve as a condenser, and low pressure refrigerant flows into some or all of the at least one second heat exchanger to cause them to serve as at least one evaporator, and
heating operation, in which low pressure refrigerant flows into the first heat exchanger to cause it to serve as an evaporator, and high pressure refrigerant flows into some or all of the at least one second heat exchanger to cause them to serve as at least one condenser,
wherein during the cooling operation, the refrigerant circulates through the circuit without going through the third expansion device, and the high pressure refrigerant is introduced on a suction side of the compressor via the second expansion device and the suction injection pipe, and
during the heating operation, the refrigerant circulates through the circuit by going through the third expansion device, and the medium pressure refrigerant generated by the third expansion device is introduced on a suction side of the compressor via the second expansion device and the suction injection pipe.

3. The air conditioning apparatus of claim 1 , comprising
a first branching unit that causes refrigerant to branch from a refrigerant channel in a case where refrigerant is flowing from the first heat exchanger to the at least one first expansion device,
a second branching unit that diverts refrigerant from a refrigerant channel in a case where refrigerant is flowing from the at least one first expansion device to the first heat exchanger;
a branch pipe that connects the first branching unit and the second branching unit, with the suction injection pipe connected thereto,
a first conducting device installed between the first branching unit and a joint between the branch pipe and the suction injection pipe, and
a second conducting device installed between the second branching unit and the joint.

4. The air conditioning apparatus of claim 3 , wherein
the first conducting device is an opening/closing device that opens and closes a refrigerant channel in the branch pipe, and
the second conducting device is a backflow prevention device that conducts refrigerant only in a flowing direction from the second branching unit to the suction injection pipe.

5. The air conditioning apparatus of claim 3 , wherein
the first branching unit is placed such that refrigerant flows in from a same direction in both cases of the cooling operation and the heating operation.

6. The air conditioning apparatus of claim 3 , wherein
the first branching unit and the second branching unit are placed such that a flow of refrigerant in an opposite direction with respect to a gravitational direction is formed and diverted.

7. The air conditioning apparatus of claim 3 , wherein
the first conducting device is a backflow prevention device that conducts refrigerant only in a flowing direction from the first branching unit to the suction injection pipe, and
the second conducting device is a backflow prevention device that conducts refrigerant only in a flowing direction from the second branching unit to the suction injection pipe.

8. The air conditioning apparatus of claim 7 , wherein
the first branching unit is placed such that a direction of refrigerant flow into the first branching unit is reversed in direction between the case of the cooling operation and the case of the heating operation.

9. The air conditioning apparatus of claim 3 , wherein
during the cooling operation, the first branching unit is placed such that a flow of refrigerant in an opposite direction with respect to a gravitational direction is formed and diverted, and
during the cooling operation and during the heating operation, the second branching unit is placed such that a flow of refrigerant in an opposite direction with respect to a gravitational direction is formed and diverted.

10. The air conditioning apparatus of claim 1 , wherein
the second expansion device is provided with a refrigerant expansion unit that varies an aperture area in a channel, and a refrigerant mixing device that mixes refrigerant in a two-phase state on a refrigerant inflow side of the refrigerant expansion unit.

11. The air conditioning apparatus of claim 1 , further comprising
a controller that
controls the second expansion device such that either a refrigerant discharge temperature on a discharge side of the compressor, or a refrigerant discharge superheat degree computed from the refrigerant discharge temperature and a pressure on a discharge side of the compressor, approaches a target value, or is within a target range and
controls a flow rate of refrigerant flowing to a suction side of the compressor via the second expansion device and the suction injection pipe.

12. The air conditioning apparatus of claim 11 , further comprising
a detection device that detects a pressure or a temperature of the medium pressure refrigerant,
wherein the controller controls the third expansion device such that a detected pressure of the detection device or a saturation pressure of a detected temperature of the detection device, or alternatively, a detected temperature of the detection device or a saturation temperature of the detected pressure of the detection device, approaches a target value, or is within a target range.

13. The air conditioning apparatus of claim 6 , wherein
the compressor, the first refrigerant flow switching device, and the first heat exchanger are housed in an outdoor unit,
the at least one first expansion device and the at least one second heat exchanger are housed in a relay unit,
the outdoor unit and the relay unit are connecte

Assignees

• Yamashita Koji
• Hatomura Takeshi
• Ishimura Katsuhiro
• Wakamoto Shinichi
• Takenaka Naofumi
• Mitsubishi Electric Corp

Inventors

• Yamashita Koji
• Hatomura Takeshi
• Ishimura Katsuhiro
• Wakamoto Shinichi
• Takenaka Naofumi

Classifications

• F25B2313/003

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

• F25B2313/0313

  Pressure sensors near the outdoor heat exchanger · CPC title

• F25B2341/0662

  Mechanical Engineering · mapped topic

• F25B2313/0272

  using bridge circuits of one-way valves · CPC title

• F25B2313/02331

  during cooling · CPC title