Air conditioning device

An air conditioning device comprising:

• a refrigerant circuit including an outdoor unit and a plurality of indoor units, the outdoor unit being connected to the plurality of indoor units via an interconnecting pipe;
• an oil collection controller;
• and
• an operation controller controlling an operation of the refrigerant circuit, wherein
• the interconnecting pipe includes:
• a liquid interconnecting pipe including a liquid main pipe connected to the outdoor unit, and a plurality of liquid branch pipes branching off from the liquid main pipe, each of the plurality of liquid branch pipes connected to a corresponding one of the indoor units;
• and
• a gas interconnecting pipe including a gas main pipe connected to the outdoor unit, and a plurality of gas branch pipes branching off from the gas main pipe, each of the plurality of gas branch pipes connected to a corresponding one of the indoor units, wherein
• the operation controller is configured to
• calculate, at predetermined time intervals, an amount of refrigerating machine oil accumulated in the gas interconnecting pipe during operation of the air conditioning device using the oil collection controller,
• integrate the amount calculated for each predetermined time interval, and
• perform, when a value of the integration exceeds a set amount, an oil collecting operation for collecting the refrigerating machine oil in the refrigerant circuit into the compressor;
• the oil collection controller includes
• an oil accumulation amount calculator configured to, at each predetermined time interval,
• (i) determine that, when a flow rate of a gaseous refrigerant in the gas main pipe is lower than a preset lower limit flow rate in the gas main pipe, the refrigerating machine oil is accumulated in the gas main pipe, and calculate an amount of the refrigerating machine oil accumulated in the gas main pipe as the amount of oil accumulated in the gas interconnecting pipe, and
• (ii) determine that, when the flow rate of the gaseous refrigerant in the gas main pipe is higher than the preset lower limit flow rate in the gas main pipe and the plurality of gas branch pipes are determined to include a gas branch pipe having a flow rate of the gaseous refrigerant higher than a preset lower limit flow rate in the plurality of gas branch pipes and a gas branch pipe having a flow rate of the gaseous refrigerant lower than the preset lower limit flow rate in the plurality of gas branch pipes, the refrigerating machine oil is accumulated in the gas branch pipe having the flow rate of the gaseous refrigerant lower than the preset set lower limit flow rate in the plurality of gas branch pipes, and calculate an amount of the refrigerating machine oil accumulated in the gas branch pipe having the lower flow rate in the plurality of gas branch pipes as the amount of oil accumulated in the gas interconnecting pipe.