Abstract: When an expansion mechanism (60) having an expansion chamber (62) is equipped with a backflow prevention mechanism (80) to suppress the outflow of fluid from the expansion chamber (62) to a communication path (72), it is possible to reduce dead volume in the expansion chamber (62) during operation with the circulation control mechanism (73,75,76) closed.

Abstract: A refrigerant circuit (20) includes, in order to perform a vapor compression supercritical refrigeration cycle, a compression mechanism (30), an outdoor heat exchanger (21), an expansion mechanism (40), and an indoor heat exchanger (23). The expansion mechanism (40) includes, for the two-stage expansion of refrigerant in the refrigerant circuit (20), a first throttle mechanism (41) variable in the amount of throttling and a second throttle mechanism (42) variable in the amount of throttling. In the cooling operation mode, there is derived a target value for the pressure of high pressure refrigerant in the refrigerant circuit (20), from the temperature of refrigerant at the outlet of the outdoor heat exchanger (21) and the temperature of air at the inlet of the outdoor heat exchanger (21).

Abstract: A refrigerating apparatus (10) includes a refrigerant circuit (11) in which a compressor (20), a radiator (14), an expander (30), and a cooler (15) are connected to each other in order through refrigerant pipes, in which a rotating shaft (22) of a motor is connected to a compression mechanism (21) included in the compressor (20) while a rotating shaft (32) of a generator (33) is connected to an expansion mechanism (31) included in the expander (30). The refrigerating apparatus (10) further includes an electric power input mechanism (41, 43) for allowing the generator (33) to function as a motor. This secures the operation of the expander (30) at a start of the apparatus to secure the start of a system, thereby attaining reliable control of the start-up performance at the start.

Abstract: A casing (31) houses therein an expansion mechanism (60) and a compression mechanism (50). The expansion mechanism (60) has a rear head (62) in which a pressure snubbing chamber (71) is provided. The pressure snubbing chamber (71) is divided by a piston (77) into an inflow/outflow chamber (72) which fluidly communicates with an inflow port (34) and a back pressure chamber (73) which fluidly communicates with the inside of the casing (31). The piston (77) is displaced in response to suction pressure variation whereby the volume of the inflow/outflow chamber (72) varies. This enables the inflow/outflow chamber (72) to directly perform supply of refrigerant to or suction of refrigerant from the inflow port (34) which is a source of pressure variation, thereby making it possible to effectively inhibit suction pressure variation.

Abstract: In a refrigerant circuit (11), a compressor (20) and an expander (30) are provided separately. An expander casing (34) is connected to a delivery pipe (26) of the compressor (20) and high pressure refrigerant passes through the inside of the expander casing (34). Therefore, the compressor casing (24) and the expander casing (34) are equalized in their internal pressure. An oil distribution pipe (41) for connection of an oil sump (27) of the compressor (20) and an oil sump (37) of the expander (30) is provided with an oil regulating valve (52). The oil regulating valve (52) is controlled in response to a signal outputted from an oil level sensor (51). When the oil regulating valve (52) is opened, the oil sump (27) within the compressor casing (24) and the oil sump (37) within the expander casing (34) fluidly communicate with each other whereby refrigeration oil travels through the oil distribution pipe (41).

Abstract: A buffer container (71) is connected to an outflow port (33) of an expansion mechanism (60). The buffer container (71) is shaped like a cylinder extending in the direction of refrigerant flow and has a greater transverse cross sectional area than that of the outflow port (33). The buffer container (71) contains therein a flow stabilizing plate (75) having a mesh part (75a) shaped like a circular plate. The variation in pressure is reduced by pressure supply and pressure absorption by the buffer container (71) and, in addition, refrigerant droplets are made fine in size during passage through the flow stabilizing plate (75).

Abstract: A refrigeration apparatus having a refrigerant circuit (20) for performing a vapor compression refrigeration cycle is disclosed. Refrigerant in a wet state, which provides an optimum coefficient of performance (COP) for a present operating condition, is drawn into the compressor (31). If the operating condition changes, the opening of an expansion valve (23) is adjusted such that the suction refrigerant of the compressor (31) is brought into a wet state which provides an optimum coefficient of performance for a new operating condition.

Abstract: In a compression/expansion unit (30) serving as a fluid machine, both of a compression mechanism (50) and an expansion mechanism (60) are contained in a single casing (31). A shaft (40) coupling the compression mechanism (50) to the expansion mechanism (60) has an oil feeding channel (90) formed therein. Refrigerating machine oil accumulated at the bottom of the casing (31) is sucked up into the oil feeding channel (90) and fed to the compression mechanism (50) and the expansion mechanism (60). The refrigerating machine oil fed to the expansion mechanism (60) is discharged from the expansion mechanism (60) together with the refrigerant after expansion, flows through the refrigerant circuit and then flows back to the compression mechanism (50) in the compression/expansion unit (30).

Abstract: A refrigerant circuit (11) of an air conditioner (10) includes a compressor (20) and an expander (30). In the compressor (20), refrigerator oil is supplied from an oil reservoir (27) to a compression mechanism (21). In the expander (30), the refrigerator oil is supplied from an oil reservoir (37) to an expansion mechanism (31). The inner pressures of the compressor casing (24) and the expander casing (34) are the high pressure and the low pressure of the refrigeration cycle, respectively. An oil adjusting valve (52) is provided in an oil pipe (42) connecting the compressor casing (24) and the expander casing (34). The oil amount adjusting valve (52) is operated on the basis of an output signal of an oil level sensor (51). When the oil amount adjusting valve (52) is opened, the refrigerator oil flows from the oil reservoir (27) in the compressor casing (24) toward the oil reservoir (37) in the expander casing (34) through the oil pipe (42).

Abstract: A refrigerant circuit (10) includes a gas-liquid separator (15) and a compressor (30) including a low pressure side compression mechanism (34) and a high pressure side compression mechanism (35) connected to each other by means of a drive shaft (33). In the refrigerant circuit (10), a two-stage compression/two-stage expansion refrigeration cycle is performed with CO2 refrigerant utilized as that at its critical pressure. In the compressor (30), a volume ratio V2/V1 of the displacement volume V2 of the second compression mechanism (35) to that V1 of the first compression mechanism is set within a range between 0.8 and 1.3, both exclusive.

Abstract: The low-side pressure of a refrigeration cycle and the refrigerant temperature at the exit of a gas cooler under reference operating conditions are employed as a reference low pressure and a reference refrigerant temperature, respectively, and the high-side pressure of the refrigeration cycle at which the COP of the refrigeration cycle reaches a maximum value under the reference operating conditions is employed as a reference high pressure.

Abstract: A positive displacement expander includes a volume change mechanism (90) for changing the volume of a first fluid chamber (72) of an expansion mechanism (60). The expansion mechanism (60) includes a first rotary mechanism (70) and a second rotary mechanism (80) each having a cylinder (71, 81) containing a rotor (75, 85). The first fluid chamber (72) of the first rotary mechanism (70) and a second fluid chamber (82) of the second rotary mechanism (80) are in fluid communication with each other to form an actuation chamber (66). Meanwhile, the first fluid chamber (72) of the first rotary mechanism (70) is smaller than the second fluid chamber (82) of the second rotary mechanism (80). The volume change mechanism (90) includes an auxiliary chamber (93) fluidly communicating with the first fluid chamber (72) and an auxiliary piston (92) for changing the volume of the auxiliary chamber (93). The auxiliary chamber (93) is in fluid communication with the first fluid chamber (72) of the first rotary mechanism (70).

Abstract: When an expansion mechanism (60) having an expansion chamber (62) is equipped with a backflow prevention mechanism (80) to suppress the outflow of fluid from the expansion chamber (62) to a communication path (72), it is possible to reduce dead volume in the expansion chamber (62) during operation with the circulation control mechanism (73,75,76) closed.

Abstract: The upper and lower end surfaces (67b, 67c) of a rotary piston (67) are formed with annular seal grooves (91) extending along the annular end surfaces (67b, 67c), and an annular lip seal (92) is fitted in each of the seal grooves (91). Thereby, the lubricating oil fed from oil feed grooves (49) in the shaft (40) rarely flows from between the upper and lower end surfaces (67b, 67c) of the rotary piston (67) and front and rear heads (61, 62) and into the fluid chamber (65) of a cylinder (63), so that shortage of lubricating oil is eliminated.

Abstract: A refrigerant circuit (10) of a refrigeration apparatus is filled up with carbon dioxide as a refrigerant. In the refrigerant circuit (10), a first compressor (21) and a second compressor (22) are arranged in parallel. The first compressor (21) is connected to both an expander (23) and a first electric motor (31), and is driven by both of the expander (23) and the first electric motor (31). On the other hand, the second compressor (22) is connected only to a second electric motor (32), and is driven by the second electric motor (32). In addition, the refrigerant circuit (10) is provided with a bypass line (40) which bypasses the expander (23). The bypass line (40) is provided with a bypass valve (41). And, the capacity of the second compressor (22) and the valve opening of the bypass valve (41) are regulated so that the COP of the refrigeration apparatus is improved after enabling the refrigeration apparatus to operate properly in any operation conditions.

Abstract: In a compression/expansion unit (30) serving as a fluid machine, both a compression mechanism (50) and an expansion mechanism (60) are housed in a single casing (31). An oil supply passageway (90) is formed in a shaft (40) by which the compression mechanism (50) and the expansion mechanism (60) are coupled together. Refrigeration oil accumulated in the bottom of the casing (31) is drawn up into the oil supply passageway (90) end is supplied to the compression mechanism (50) and to the expansion mechanism (60). Surplus refrigeration oil, which is supplied to neither of the compression and expansion mechanisms (50) and (60), is discharged out of the terminating end of the oil supply passageway (90) which opens at the upper end of the shaft (40). Thereafter, the surplus refrigeration oil flows into an oil return pipe (102) from a lead-out hole (101) and is returned back towards a second space (39).

Abstract: Disclosed is a displacement type expansion machine. In the displacement type expansion machine, a communicating passage (72) for allowing fluid communication between an expansion-process intermediate position and an outflow position in an expansion chamber (62) is provided thereby to allow the fluid at the outflow side to return to the expansion chamber (62). Such arrangement prevents the pressure of the expansion chamber (62) from being lowered to an excessive extent in predetermined operating conditions, thereby avoiding the drop in power recovery efficiency.

Abstract: A first and a second expansion and compression machine (30, 40) having different volume ratios (Vc/Ve) are connected in parallel to a refrigerant circuit (10) of a refrigeration apparatus. Expanders (31, 41) of the expansion and compression machines (30, 40) are connected in parallel. Compressors (32, 42) of the expansion and compression machines (30, 40) are also connected in parallel. Upon variation in the operating condition of the refrigeration apparatus, the ratio of rotation speed between the expansion and compression machines (30, 40) is controlled by a controller (60). This, as a result, allows the refrigeration apparatus to operate at a COP close to an ideal condition.

Abstract: Oil supply grooves (74, 84) are formed respectively in a rotating shaft (70) of a compression mechanism (50) integral with an electric motor (40) and in a rotating shaft (80) of an expansion mechanism (60). The rotating shafts (70, 80) are coupled together by engagement between an engagement convex portion (85) and an engagement concave portion (75) which are formed respectively in shaft ends of the rotating shafts (70, 80). And, a seal groove (S) is formed in the peripheral surface of the engagement convex portion (85) and an O-ring (R) is engaged into the seal groove (S). Hereby, lubrication oil leakage from between the engagement convex portion (85) and the engagement concave portion (75) is prevented.

Abstract: Two rotary mechanism parts (70, 80) are provided in a rotary expander (60). The first rotary mechanism part (70) is smaller in displacement volume than the second rotary mechanism part (80). A first low-pressure chamber (74) of the first rotary mechanism part (70) and a second high-pressure chamber (83) of the second rotary mechanism part (80) are fluidly connected together by a communicating passageway (64), thereby forming a single expansion chamber (66). High-pressure refrigerant introduced into the first rotary mechanism part (70) expands in the expansion chamber (66). An injection passageway (37) is fluidly connected to the communicating passageway (64). When an motor-operated valve (90) is placed in the open state, high-pressure refrigerant is introduced into the expansion chamber (66) also from the injection passageway (37). This makes it possible to inhibit the drop in power recovery efficiency, even in the condition that causes the actual expansion ratio to fall below the design expansion ratio.