Abstract: A refrigeration cycle apparatus (100) includes a first compressor (101), a second compressor (102), a radiator (4), an evaporator (6), and a pipe branching portion (30). The first compressor (101) has a first compression mechanism (1) and an expansion mechanism (5). The second compressor (102) has a second compression mechanism (2). The pipe branching portion (30) serves as a flow passage for introducing a refrigerant from the evaporator (6) to the first compression mechanism (1) and the second compression mechanism (2), respectively. The pipe branching portion (30) includes an inlet pipe (31) for receiving the refrigerant from the evaporator (6), a first branch outlet pipe (32) for introducing the refrigerant flowing into the inlet pipe (31) to the first compression mechanism (1), and a second branch outlet pipe (33) for introducing the refrigerant flowing into the inlet pipe (31) to the second compression mechanism (2).

Abstract: A refrigeration cycle apparatus 100 is provided with a working fluid circuit 106 and a first bypass passage 112. The working fluid circuit 106 is formed of a first compressor 101, a heat radiator 102, an expander 103, an evaporator 104, a second compressor 105, and flow passages 106a to 106e connecting these components in this order. The expander 103 and the second compressor 105 are coupled to each other by a power-recovery shaft 107 so that the second compressor 105 is driven by the power recovered by the expander 103. The first bypass passage 112 communicates between a portion from the discharge port of the first compressor 101 to the suction port of the expander 103 in the working fluid circuit 106 and a portion from the outlet of the evaporator 104 to the suction port of the second compressor 105 in the working fluid circuit 106, at the time of activation of the refrigeration cycle apparatus 100.

Abstract: A refrigeration cycle apparatus includes a first compressor 1, which is an expander-compressor unit, and a second compressor 2. A first compression mechanism 11 of the first compressor 1 and a second compression mechanism 21 of the second compressor 2 are disposed in parallel with each other in a refrigerant circuit 30. The refrigeration cycle apparatus is provided with an injection passage 6. A controller 7 controls a first motor 12 of the first compressor 1 and a second motor 22 of the second compressor 2, and an opening of an injection valve 61. The controller 7 performs an optimizing operation for the opening of the injection valve. In the optimizing operation, the opening of the injection valve 61 is brought closer to a fully closed state or closer to a fully opened state while a pressure or a temperature of a discharged refrigerant guided to a radiator 4 through a first pipe 3a is kept approximately constant.

Abstract: A sub-compressor (23) is provided between a compressor (22) and a power-recovery device (24). A refrigerant after preliminarily being compressed by the sub-compressor (23) is allowed to flow into the compressor (22). Since the sub-compressor (23) and the power-recovery device (24) have approximately the same temperature, heat transfer hardly occur therebetween. Heat transfer occurs between the compressor (22) at high temperature and the sub-compressor (23) at low temperature. However, even if the heat from the compressor (22) heats the refrigerant in the sub-compressor (23), the refrigerant discharged from the sub-compressor (23) is delivered to the compressor (22), and thus the temperature of the sub-compressor (23) scarcely increases.

Abstract: An expander-compressor unit (200) includes a closed casing (1), a compression mechanism (2), an expansion mechanism (3), a shaft (5), and an oil pump (6). The shaft (5) includes an upper shaft (5s) provided with an upper eccentric portion (5a) for the compression mechanism (2), and a lower shaft (5t) provided with lower eccentric portions (5d and 5c) for the expansion mechanism (3) and an intermediate eccentric portion (5e) for the oil pump (6). The expansion mechanism (3) has an upper bearing member (45) for supporting a supported portion (5f) of the lower shaft (5t) located immediately above the lower eccentric portion (5d). The intermediate eccentric portion (5e) has a diameter equal to or less than that of the supported portion (5f).

Abstract: An expander-compressor unit (200A) includes a closed casing (1), a compression mechanism (2), an expansion mechanism (3), a shaft (5), and an oil pump (6). The shaft (5) couples the compression mechanism (2) to the expansion mechanism (3) so that power recovered by the expansion mechanism (3) is transferred to the compression mechanism (2). The oil pump (6) is disposed between the compression mechanism (2) and the expansion mechanism (3), and supplies an oil held in an oil reservoir (25) to the compression mechanism (2). An oil supply passage (29) is formed in the shaft (5) so that the oil discharged from the oil pump (6) can be supplied to the compression mechanism (2). A lower end (29e) of the oil supply passage (29) is located below an inlet (29p) of the oil supply passage (29) formed in an outer circumferential surface of the shaft (5).

Abstract: An expander-compressor unit (200) includes a closed casing (1), a compression mechanism (2) disposed at an upper position in the closed casing (1), an expansion mechanism (3) disposed at a lower position in the closed casing (1), a shaft (5) coupling the compression mechanism (2) to the expansion mechanism (3), and an oil pump (6) disposed between the compression mechanism (2) and the expansion mechanism (3). The oil pump (6) supplies the oil held in an oil reservoir (25) to the compression mechanism (2) via a suction passage. A strainer (65) is provided to the suction passage so that the oil to be drawn into the oil pump (6) passes through the strainer.

Abstract: A fluid machine (101) includes a first compressor (107) and a second compressor (108). The first compressor (107) has a first closed casing (111), a first compression mechanism (102a), an expansion mechanism (104), and a shaft (113). A first oil reservoir (112) is formed in the first closed casing (111). The second compressor (108) has a second closed casing (125) and a second compression mechanism (102b). A second oil reservoir (126) is formed at a bottom portion in the second closed casing (125). The first closed casing (111) and the second closed casing (125) are connected to each other by an oil passage (109) so that a lubricating oil can flow between the first oil reservoir (112) and the second oil reservoir (126). An opening (109a) of the oil passage (109) on a side of the first closed casing (111) is located above the expansion mechanism (104) with respect to the vertical direction.

Abstract: There may be a case where, by simply coupling the first compressor (expander compressor unit) and the second compressor with an oil-equalizing pipe, the first compressor is not lubricated sufficiently, thereby decreasing reliability. The volumetric capacity (V1) of the first available oil space (130) of the first compressor (101) is set larger than the volumetric capacity (V2) of the second available oil space (140) of the second compressor (102). With this configuration, even if the oil level (S1) of the first oil sump (13) decreases in transition to a state of steady operation, it is possible to maintain a sufficient amount of oil in the first compressor (101), and thus high reliability as a fluid machine can be achieved.