Patent ID: 7607317
Filing Date: 2009-10-27
Classification: F25B

Abstract:
1. 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, and an expansion valve disposed in the liquid refrigerant pipe, 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; a first bypass circuit selectively conducting the refrigerant discharged from the compression mechanism to an 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 heat exchanger is caused to function as an evaporator 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, causing the heat source heat exchanger to function as a condenser, 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.