Air conditioner

Patent metadata

Field	Value
Publication number	US-9851132-B2
Application number	US-201314649098-A
Country	US
Kind code	B2
Filing date	Nov 29, 2013
Priority date	Dec 28, 2012
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

This air conditioner performs a cooling operation and a heating operation in parallel with each other with an outdoor unit and indoor units connected together through two communication pipes. The air conditioner includes a switching mechanism changing the directions of refrigerants flowing through the communication pipes depending on whether a heating dominant operation is being performed in a first load region where a cooling load is relatively light or a second load region where the cooling load is heavier than in the first load region. In the second load region, the switching mechanism allows a low-pressure refrigerant to flow from the indoor units to the outdoor unit through the second communication pipe thicker than the first communication pipe to reduce a performance deterioration due to the pressure loss involved with the heating dominant operation.

First claim

The invention claimed is:

1. An air conditioner comprising:
a refrigerant circuit in which refrigerant flows through an outdoor unit, a gas-liquid separation unit, and a plurality of indoor units connected together through communication pipes and which is configured to be able to perform a refrigeration cycle in which cooling and heating operations are performed in parallel with each other, wherein
the communication pipes include a first communication pipe connecting the outdoor unit and the gas-liquid separation unit and a second communication pipe which has a larger inside diameter than the first communication pipe connecting the outdoor unit and the gas-liquid separation unit such that refrigerant flows from the outdoor from to the gas-liquid separation unit and from the gas-liquid separation unit to the outdoor unit,
the outdoor unit includes
a compressor that compresses the refrigerant,
an outdoor heat exchanger that exchanges heat between the refrigerant and outdoor air, and
a switching mechanism which changes the directions of the refrigerants flowing through the first and second communication pipes depending on whether a heating dominant operation to be conducted between a full-heating load operation and a balanced heating and cooling load operation is being performed in a first load region which ranges from a full-heating load to a partial-cooling load or a second load region which ranges from the partial-cooling load to balanced heating and cooling loads,

the switching mechanism includes
a switching valve that switches communication states of a discharge-side pipe of a compressor and a suction-side pipe of the compressor to allow one of the discharge-side pipe and the suction-side pipe to communicate with a gas-side end of the outdoor heat exchanger, and
a pipe switching section connected to the discharge-side pipe of the compressor, the first communication pipe, the second communication pipe, and a liquid-side end of the outdoor heat exchanger,

in the first load region, the switching mechanism allows a high-pressure refrigerant to flow from the outdoor unit to the indoor units through the second communication pipe, and allows a low-pressure refrigerant to flow from the indoor units to the outdoor unit through the first communication pipe, and
in the second load region, the switching mechanism allows the high-pressure refrigerant to flow from the outdoor unit to the indoor units through the first communication pipe, and allows the low-pressure refrigerant to flow from the indoor units to the outdoor unit through the second communication pipe.

2. The air conditioner of claim 1 , wherein in all of the regions of the heating dominant operation, the switching mechanism is configured to perform a refrigeration cycle in which an outdoor heat exchanger in the outdoor unit serves as an evaporator.

3. The air conditioner of claim 2 , wherein
the pipe switching section switched between a first position and a second position,
the pipe switching section in the first position allows the high-pressure refrigerant discharged from the compressor in the first load region to enter the second communication pipe, and allows the low-pressure refrigerant returning from the indoor units to the outdoor unit through the first communication pipe to enter the outdoor heat exchanger, and
the pipe switching section in the second position allows the high-pressure refrigerant discharged from the compressor in the second load region to enter the first communication pipe, and allows the low-pressure refrigerant returning from the indoor units to the outdoor unit through the second communication pipe to enter the outdoor heat exchanger.

4. The air conditioner of claim 3 , wherein
the operation mode switching section switches between a first position where the heating dominant operation is conducted and a second position where the cooling dominant operation is conducted,
the operation mode switching section in the first position allows the high-pressure refrigerant discharged from the compressor to enter the first communication pipe or the second communication pipe through the pipe switching section, and also allows the low-pressure refrigerant evaporated in the outdoor heat exchanger to enter the compressor, and
the operation mode switching section in the second position allows the high-pressure refrigerant discharged from the compressor to enter the first communication pipe through the outdoor heat exchanger and the pipe switching section, and also allows the refrigerant returning to the outdoor unit through the second communication pipe to enter the compressor.

5. The air conditioner of claim 4 , wherein
the pipe switching section includes four connection points and four passages,
the pipe switching section is implemented as a switching circuit in which
the first and second connection points are connected together through the first passage,
the second and third connection points are connected together through the second passage,
the third and fourth connection points are connected together through the third passage,
the fourth and first connection points are connected together through the fourth passage, and

the passages of the switching circuit include opening/closing mechanisms, respectively.

6. The air conditioner of claim 5 , wherein
the first connection point of the pipe switching section is pipe-connected to the discharge-side pipe of the compressor,
the second connection point is pipe-connected to the first communication pipe,
the third connection point is pipe-connected to a liquid-side end of the outdoor heat exchanger,
the fourth connection point is connected to the second communication pipe through a branch pipe and also connected to the suction-side pipe of the compressor through a branch pipe, and
an on-off valve is provided for the branch pipe between the fourth connection point and the suction-side pipe of the compressor.

7. The air conditioner of claim 6 , further comprising:
a plurality of operation switching units, each operation switching unit
connected between the gas-liquid separation unit and a corresponding one of the indoor units, and
including switching valves switching flows of a liquid refrigerant and a gas refrigerant in the corresponding indoor unit.

8. The air conditioner of claim 5 , further comprising:
a plurality of operation switching units, each operation switching unit
connected between the gas-liquid separation unit and a corresponding one of the indoor units, and
including switching valves switching flows of a liquid refrigerant and a gas refrigerant in the corresponding indoor unit.

9. The air conditioner of claim 8 , wherein the gas-liquid separation unit and the operation switching units are integrated together to form a single cooling/heating switching unit including the gas-liquid separator and the switching valves.

10. The air conditioner of claim 4 , further comprising:
a plurality of operation switching units each operation switching unit
connected between the gas-liquid separation unit and a corresponding one of the indoor units, and
including switching valves switching flows of a liquid refrigerant and a gas refrigerant in the corresponding indoor unit.

11. The air conditioner of claim 10 , wherein the gas-liquid separation unit and the operation switching units are integrated together to form a single cooling/heating switching unit including the gas-liquid separator and the switching valves.

12. The air conditioner of claim 3 , further comprising:
a plurality of operation switching units, each operation switching unit
connected between the gas-liquid separation unit and a corresponding one o

Assignees

• Daikin Ind Ltd

Inventors

• Kawano Satoshi
• Matsuoka Shinya
• Oka Masahiro
• Susaki Mari

Classifications

• F25B2313/0231

  with simultaneous cooling and heating · CPC title

• F25B2313/02791

  using shut-off valves · CPC title

• F25B2400/23

  Separators · CPC title

• F25B41/04 Primary

  Mechanical Engineering · mapped topic

• F25B2500/01

  Geometry problems, e.g. for reducing size · CPC title