Air conditioning device

An air conditioning device which includes:

• a refrigerant circuit including an outdoor unit and indoor units connected to each other via an interconnecting pipe;
• and an operation controller controlling operation of the refrigerant circuit,
• the interconnecting pipe including:
• a liquid main pipe connected to the outdoor unit, and liquid branch pipes branching off from the liquid main pipe and each connected to a corresponding one of the indoor units;
• and a gas main pipe connected to the outdoor unit, and gas branch pipes branching off from the gas main pipe and each connected to a corresponding one of the indoor units, and
• the controller including an air-conditioning capacity controller determining a target value of an evaporation temperature or a condensing temperature of the refrigerant circuit, depending on air-conditioning load in a room, and, based on the target value, controlling operational capacity of the compressor in the refrigerant circuit, wherein
• the operation controller includes an oil collection controller calculating an amount of refrigerating machine oil accumulated in the interconnecting pipe during the operation, and when the calculated amount exceeds a preset amount, performing oil collecting operation for collecting the refrigerating machine oil in the refrigerant circuit into the compressor, and
• the oil collection controller includes an oil accumulation amount calculator:
• comparing (i) a current value of the target evaporation temperature or the target condensing temperature of the refrigerant circuit with (ii) a set value of the evaporation temperature or the condensing temperature;
• determining, when the gas branch pipes are determined to include a gas branch pipe which does not satisfy the lower limit flow rate, that the refrigerating machine oil accumulates in the gas branch pipe;
• and calculating an amount of the refrigerating machine oil accumulated in the gas branch pipe, the set value being a reference value determined, for each of the indoor units, to correspond to a lower limit flow rate, of a gaseous refrigerant, necessary for the refrigerating machine oil to flow together with the refrigerant, and not to accumulate, in the gas branch pipes.