| 摘要 |
PROBLEM TO BE SOLVED: To prevent failure by lubricating each of compressors 11, 12, 55 with minimum refrigerator oil, in a refrigerating apparatus comprising a refrigerant circuit 6 where a low-stage compressor 55 and a high-speed compressors 11, 12 are connected in series to perform two-stage refrigerating cycle. SOLUTION: A pressure regulating valve 71 for reducing a pressure on a suction side of the high-stage compressors 11, 12 less than a pressure in the dome of the low-stage compressor 55 is connected to a delivery side of the low-stage compressor 55, one end of an oil return passage 72 is connected to the dome of the low-stage compressor 55, and the other end is connected to the suction side of the high-stage compressors 11, 12 by bypassing the pressure regulating valve 71. Thus, the refrigerator oil stored in the dome of the low-stage compressor 55 can be returned to the high-stage compressors 11, 12. COPYRIGHT: (C)2007,JPO&INPIT
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