| 摘要 |
PROBLEM TO BE SOLVED: To avoid a trouble and to improve reliability by assuring a storage amount of a refrigerating machine oil in a high-stage compressor of a two-stage compression refrigerating cycle. SOLUTION: A low-stage compressor 11 and a high-stage compressor 12 are provided in a refrigerant circuit 10, and constituted to conduct a two-stage compression type refrigerating cycle. A discharge side of the compressor 11 and a suction side of the compressor 12 are connected by a first discharge tube 21. A gas-liquid separator 16 is provided between a first expansion valve 15 and a second expansion valve 17, The separator 16 separates an intermediate pressure refrigerant into a gas and a liquid. The separator 16 is connected to a discharge tube 21 by an injection tube 40. An internal pipeline 41 of the tube 40 is formed in a J-shape, and an oil hole is formed at a bent lower end. A refrigerating machine oil stored in the separator 16 flows from the hole to the tube 40 and to the compressor 12 together with a gas refrigerant.
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