| 摘要 |
If a refrigerating cycle has been formed, the flow-rate adjusting valves (11), (21) and (31) are controlled in opening. When the temperature (Td) of refrigerant discharged rises above a preset value (Tds), the minimum opening (Qmin) for the flow-rate adjusting valves (11), (21) and (31) is changed to a value greater than a normal value. An oil pipe (31) is connected between the sealed case (1c) of a compressor (1) and a refrigerant-drawing pipe (18) through which refrigerant passes to be drawn into the compressor (1). A capillary tube (33) is provided on the oil pipe (31). Two temperature sensors (34, 35) detect temperatures at those parts of the oil pipe (31), which are at upstream and downstream of the capillary tube (33), respectively. An amount of lubricating oil (L) in the sealed case (1c) is detected from the temperatures detected. <IMAGE>
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