| 摘要 |
PURPOSE:To enable an early stable operation to be attained when the number of operating devices is decreased in response to a variation of a freezing load by a method wherein at least one of a plurality of compressors is of a variable volume type, the freezing load is judged, the variable volume type is operated under a high compression power when the load is less than a full capability of the operating compressor and subsequently it determined the operating mode and the variable volume type is controlled in its volume. CONSTITUTION:During a concurrent operation of a variable volume type compressor 30A and a positive volume type compressor 30B, a control valve 36 is adjusted, a volume of the compressor 30A is varied automatically in a stepless manner and a full compressing capability corresponds to a freezing load. In the event that the load is decreased and the low pressure is decreased lower than a cut-out value of a switch 38, a discriminating means 46 judges that the load is less than a full compression capability, an operating mode determining means 47 determines a stopping of the positive volume type compressor 30B and the degree-of-opening determining means 43 makes the control valve zero. In this way, the compressor 30A is once operated at its maximum capability, the compressor 30B is stopped and at the same time a degree of opening of the control valve 30 is adjusted so as to correspond to the load and then the compressor 30A is operated for its controlling volume. With such an arrangement, the low pressure reaches fast to the set value and the operation is stabilized fast. |
