Air conditioner with oil recovery function

An air conditioner comprising:

• a refrigerant circuit including a compression mechanism, a heat source heat exchanger configured such that refrigerant enters the heat source heat exchanger at a position on a lower portion of the heat source heat exchanger, and leaves the heat source heat exchanger from a position on an upper portion of the heat source heat exchanger when the heat source heat exchanger functions as an evaporator of the refrigerant, a plurality of utilization heat exchangers, a liquid refrigerant pipe connecting the heat source heat exchanger and the utilization heat exchangers, an expansion valve disposed in the liquid refrigerant pipe, a heat source switch mechanism configured to switch between a condensation operation switched state that causes the heat source heat exchanger to function as a condenser of the refrigerant discharged from the compression mechanism and an evaporation operation switched state that causes the heat source heat exchanger to function as an evaporator of the refrigerant flowing through the liquid refrigerant pipe, a high-pressure gas refrigerant pipe connected between an intake side of the compression mechanism and the heat source switch mechanism and configured to branch the refrigerant discharged from the compression mechanism before the refrigerant flows into the heat source switch mechanism, a plurality of utilization switch mechanisms configured to switch between a cooling operation switched state that causes the heat source heat exchanger to function as an evaporator of the refrigerant flowing through the liquid refrigerant pipe and a heating operation switched state that causes the heat source heat exchanger to function as a condenser of the refrigerant flowing through the high-pressure gas refrigerant pipe, and a low-pressure gas refrigerant pipe that sends the refrigerant evaporated in the utilization heat exchangers to the intake side of the compression mechanism;
• a first bypass circuit selectively conducting the refrigerant discharged from the compression mechanism to the intake side of the compression mechanism;
• and
• an oil returning circuit connecting the lower portion of the heat source heat exchanger and the intake side of the compression mechanism, the oil returning circuit being arranged in a unit with the heat source heat exchanger and compression mechanism separate from units having the plurality of utilization heat exchangers, the oil returning circuit being configured to return oil from the heat source heat exchanger to the compression mechanism within the unit,
• the refrigerant circuit, the first bypass circuit and the oil returning circuit being further operatively arranged with respect to one another such that when the heat source switch mechanism is switched to the evaporation operation switched state, an oil recovery operation is conducted by temporarily causing the refrigerant discharged from the compression mechanism to be bypassed to the intake side of the compression mechanism via the first bypass circuit, switching the heat source switch mechanism to the condensation operation switched state, and closing the expansion valve, the refrigerant being discharged from the compression mechanism is caused to flow into the heat source heat exchanger, and refrigerating machine oil accumulating inside the heat source heat exchanger being returned to the intake side of the compression mechanism via the oil returning circuit.

An air conditioner comprising:

• a refrigerant circuit including a compression mechanism, a heat source heat exchanger configured such that refrigerant enters the heat source heat exchanger at a position on a lower portion of the heat source heat exchanger, and leaves the heat source heat exchanger from a position on an upper portion of the heat source heat exchanger when the heat source heat exchanger functions as an evaporator of the refrigerant, and a plurality of utilization heat exchangers, the refrigerant circuit being configured to switch to cause the heat source heat exchanger and the utilization heat exchangers to function separately as evaporators or condensers of the refrigerant;
• and
• an oil returning circuit that connects the lower portion of the heat source heat exchanger and an intake side of the compression mechanism, the oil returning circuit being arranged in a unit with the heat source heat exchanger and compression mechanism separate from units having the plurality of utilization heat exchangers, the oil returning circuit being configured to return oil from the heat source heat exchanger to the compression mechanism within the unit,
• the refrigerant circuit and the oil returning circuit being further operatively arranged with respect to each other such that when the heat source heat exchanger is caused to function as an evaporator, an oil recovery operation is conducted by temporarily causing the heat source heat exchanger to function as a condenser, the refrigerant being discharged from the compression mechanism is caused to flow into the heat source heat exchanger, and refrigerating machine oil accumulating inside the heat source heat exchanger is returned to the intake side of the compression mechanism via the oil returning circuit.