JP4114337B2 - Refrigeration equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a refrigeration apparatus that performs a vapor compression refrigeration cycle, and particularly relates to a refrigeration apparatus provided with an expander instead of an expansion valve or a capillary tube as a refrigerant expansion mechanism.
[0002]
[Prior art]
  Conventionally, refrigeration apparatuses that perform a vapor compression refrigeration cycle by circulating a refrigerant in a closed circuit are known and widely used as air conditioners and the like. As this type of refrigeration apparatus, for example, as disclosed in Japanese Patent Laid-Open No. 10-54617, carbon dioxide is used as a refrigerant in a refrigerant circuit in which a compressor, a radiator, an expansion mechanism, and an evaporator are sequentially connected. In addition, one in which the high pressure of the refrigeration cycle is set to be higher than the critical pressure of the refrigerant is known. In this refrigeration apparatus, since the refrigerant is compressed to the critical pressure or higher in the compressor, there is a problem that the power consumption of the compressor motor increases and a high COP (coefficient of performance) cannot be obtained.
[0003]
  For this problem, as disclosed in Japanese Patent Application Laid-Open No. 2001-107881, a countermeasure for providing an expander in the refrigeration apparatus has been proposed. The expander as used in this specification is synonymous with a prime mover as a kind of fluid machine. In this case, the expander is provided as a refrigerant expansion mechanism in the refrigeration apparatus instead of the expansion valve and the capillary tube. In the expander, the internal energy of the high-pressure refrigerant is converted into mechanical power, and the obtained power is used for driving the compressor, thereby reducing the power consumption of the compressor motor.
[0004]
  In the apparatus of the above publication, one fluid machine is configured by housing the compressor and the expander together with a motor in an integral casing. In this fluid machine, an oil pump is provided at one end of the drive shaft, and an oil passage is provided in the drive shaft. The refrigerating machine oil sucked up by the oil pump is supplied to the sliding part of the compressor and the expander through the oil passage so as to lubricate the compressor and the expander.
[0005]
  The compressor of the fluid machine is a high-pressure dome type compressor (a compressor in which an oil reservoir is on the high-pressure side in the casing). In this compressor, oil supplied into the cylinder is discharged into the compressor casing together with the discharge gas. Discharged. Although the oil mist is contained in the discharge gas, a part of the oil mist collides with the inside of the casing and the surface of the motor, aggregates and becomes a liquid, falls on the casing wall surface, and returns to the oil sump. Part of the oil mist is discharged from the compressor together with the discharge gas and flows to the radiator.
[0006]
[Problems to be solved by the invention]
  On the other hand, the refrigerating machine oil supplied to the expander is mixed with the gas-liquid two-phase flow of the refrigerant in the expander. If the solubility of the refrigerating machine oil and the liquid refrigerant is high, the refrigerating machine oil dissolves in the liquid refrigerant, is discharged from the expander outlet, and flows to the evaporator.
[0007]
  Here, in the fluid machine, the influence on the performance when the refrigerating machine oil flows to the evaporator will be considered. The evaporation temperature is 10 ° C., the radiator outlet temperature is 37 ° C., the discharge pressure is 10 MPa, the compressor efficiency is 0.7, the expander efficiency is 0.6, and the oil flow rate ratio to the refrigerant passing through the evaporator is 5%. The discharge temperature is 76 ° C. In the case of a high-pressure dome, the temperature of the refrigerating machine oil supplied from the compressor to the expander is almost equal to the discharge temperature of the compressor, so 76 ° C. oil is supplied to the expander.
[0008]
  When this refrigerating machine oil passes through the evaporator, it gives heat to the refrigerant and is cooled to an evaporation temperature of 10 ° C. When the recovery is not considered, the freezing effect is 125.8 KJ / Kg, and the recovery power is 7 KJ / Kg. The freezing effect when considering recovery is
125.8 + 7 = 132.8 KJ / Kg.
[0009]
  On the other hand, when the specific heat of the oil is 2.1 KJ / Kg ° C. and the amount of heat required for cooling the oil is calculated,
(76-10) × 2.1 × 0.05 = 6.9 KJ / Kg
Therefore, the actual refrigeration effect is reduced by that amount. Therefore, the rate at which the freezing effect decreases is
6.9 / 132.8 = 0.052
As a result, the ability is reduced by about 5%.
[0010]
  As described above, when the refrigerating machine oil flows out of the expander and flows into the evaporator, the refrigerating capacity is reduced due to the sensible heat of the refrigerating machine oil. This is not limited to an integral fluid machine, and may be a problem that may occur even if the compressor and the expander are separated from each other. The present invention has been made in view of such problems, and the object of the present invention is to prevent oil from flowing into an evaporator in a refrigeration apparatus provided with an expander as an expansion mechanism of a refrigeration cycle. To prevent the decline in refrigeration capacity.
[0011]
[Means for Solving the Problems]
  The present invention solves the above problems.For the expanderRefrigerator oil is separated from the refrigerant on the outlet side of (3) so that it does not flow into the evaporator (5).It is a thing.
[0012]
  First to twelfth solving meansIn this case, the refrigerant oil is separated from the refrigerant at the outlet side of the expander (3) using carbon dioxide as the refrigerant and the refrigerating machine oil separated from the carbon dioxide in a predetermined temperature range.In the thirteenth and fourteenth solving means, the respective solving means are specified from the structural aspect.
[0013]
  Specifically, the first solving means includes a refrigerant circuit (C) in which a compressor (2), a radiator (4), an expander (3), and an evaporator (5) are connected in order. (C) assumes a refrigeration system filled with carbon dioxide as a refrigerant. The refrigeration apparatus includes an oil separator (between the outlet side of the expander (3) and the inlet side of the evaporator (5) through which the refrigeration oil contained in the refrigerant discharged from the compressor (2) flows. 6) is connected, and the refrigerating machine oil in the refrigerant circuit (C) separates into two phases from the refrigerant in a temperature range of at least −20 ° C. and the density becomes higher than that of the refrigerant in the temperature range. Composed of refrigeration oilHave. In a refrigeration apparatus used for a normal air conditioner or the like, the minimum lower limit of the evaporating temperature is set to about −20 ° C. If two-phase separation is performed at least in a temperature range of −20 ° C. or more, oil separation described later becomes possible.
[0014]
  The first solution is an oil separator. (6) Centrifugal oil separator (6) Oil separator composed of (6) Is a vertical cylindrical container (6a) Inlet pipe connected tangential to the surrounding wall (6b) And the container (6a) Refrigerant outlet pipe connected to the upper surface of (6c) And the container (6a) Oil outlet pipe connected to the bottom of (6d) And.
[0015]
  In this configuration, the expander (3) Gas-liquid two-phase refrigerant from oil separator (6) The oil separator (6) The refrigerating machine oil and the refrigerant are separated by generating a swirling flow in the interior. Refrigerator oil is heavier than refrigerant, so the container (6a) Oil collecting pipe that collects under (6d) Discharged from. On the other hand, the liquid refrigerant is entangled in the gas refrigerant as the gas refrigerant rotates, and the refrigerant outlet pipe together with the gas refrigerant. (6c) Spill from. Therefore, the evaporator (Five) Only the refrigerant flows to the (Five) Does not flow into.
[0016]
  The above configuration and operation are common to the second to fifth solving means.
[0017]
  And in the 1st solution, an oil separator (6) Refrigerant outlet pipe (6c) Is a container (6a) The refrigerant outlet pipe is arranged in the vertical direction along the inner surface of the peripheral wall of (6c) The lower end of the container (6a) It is located in the intermediate part of the height direction and is configured to open into the liquid refrigerant.
[0018]
  In this configuration, the evaporator (Five) Refrigerant outlet pipe to (6c) The oil separator (6) It is provided in contact with the inner wall, and the lower end opens into the liquid refrigerant. (Five) Only the refrigerant can be supplied without flowing the refrigerating machine oil. That is, the expander (3) Oil separator (6) After separating the refrigerating machine oil from the refrigerant flowing into the evaporator, the oil rich liquid is not entrained by the gas refrigerant, and the evaporator (Five) Liquid refrigerant can be supplied to the water.
[0019]
  In the second solution, the oil separator (6) Refrigerant outlet pipe (6c) But the container (6a) Gas refrigerant outlet pipe connected to the upper surface of (6c-g) And the container (6a) It is arranged in the vertical direction along the inner surface of the peripheral wall of the container and its lower end is a container (6a) Liquid refrigerant outlet tube that is located in the middle of the height direction and opens into the liquid refrigerant (6c-l) Gas refrigerant outlet pipe (6c-g) And liquid refrigerant outlet pipe (6c-l) Toga container (6a) Have joined outside.
[0020]
  As described above, when the liquid refrigerant and the gas refrigerant are allowed to flow separately, the oil-rich liquid can be prevented from being unnecessarily involved in the gas refrigerant, and the oil separation efficiency can be increased.
[0021]
  In the third solution, the oil separator (6) Is a container (6a) Inside the container (6a) Baffle plate with a double top structure (6e) Equipped with a container (6a) Refrigerant outlet pipe on top of (6c) Connected to the introduction pipe (6b) Is a container (6a) Baffle plate through the peripheral wall of (6e) It is characterized by being connected to.
[0022]
  In this case, the oil separator (6) When a gas-liquid two-phase refrigerant is introduced into the interior of the chamber, a refrigerant outlet pipe is provided around the entire inner wall. (6c) The same effect as that provided can be obtained. That is, the refrigerant rich liquid (6a) And baffle plate (6e) It flows out through the gap between.
[0023]
  In the fourth solution, the oil separator (6) But baffle plate (6e) The gas refrigerant circulation hole through which the gas refrigerant flows (6e-h) It has.
[0024]
  In this configuration, separate passages for the gas refrigerant and the liquid refrigerant are ensured. Baffle plate (6e) If there is no hole in the container, (6a) And baffle plate (6e) When the gas refrigerant entrains the liquid refrigerant from the gap, the oil-rich liquid may be entrained, and the oil separation efficiency can be increased. Therefore, the oil is the evaporator (Five) Can be surely prevented from flowing into.
[0025]
  In the fifth solution, the oil separator (6) Refrigerant outlet pipe (6c) Is a container (6a) The container is formed into a U-shaped bent shape inside the container. (6a) The refrigerant outlet pipe inside (6c) The upper end of the liquid refrigerant is formed at the inlet of the gas refrigerant, and the liquid refrigerant inlet hole is formed at the lower part of the U-shaped outlet pipe (6c-h) Is formed.
[0026]
  In this way, the gas refrigerant flows through the outlet pipe and the oil separator (6) Liquid refrigerant inlet hole (6c-h) Refrigerant outlet pipe (6c) Liquid refrigerant flows into the interior of the (Five) To be supplied.
[0027]
  The sixth solving means specifies a more preferable temperature range. Specifically, in the first to fifth solving means, the refrigerating machine oil is carbon dioxide in a temperature range of −50 ° C. or higher. It is characterized by being separated into a refrigerant and two phases. In a refrigeration apparatus used for a showcase, a freezer, etc., the minimum lower limit of the evaporation temperature is set to about −50 ° C. If two-phase separation is performed in a temperature range of −50 ° C. or higher, oil separation is also possible.
[0028]
  Further, the seventh to twelfth solving means taken by the present invention specifically specify the refrigerating machine oil. Among these, the seventh solving means is characterized in that the refrigerating machine oil is composed of polyalkylene glycol (PAG) in the first to fifth solving means. This PAG has a characteristic of being separated into a refrigerant and two phases in a temperature range of −50 ° C. or higher, which is a constituent requirement of the sixth solving means.
[0029]
  The eighth solving means is characterized in that the refrigerating machine oil is made of polyvinyl ether (PVE) in the first to fifth solving means.
[0030]
  A ninth solving means is characterized in that, in the first to fifth solving means, the refrigerating machine oil is composed of mineral oil.
[0031]
  A tenth solving means is characterized in that, in the first to fifth solving means, the refrigerating machine oil is composed of a polyol ester (POE).
[0032]
  The eleventh solving means is characterized in that in the first to fifth solving means, the refrigerating machine oil is made of polycarbonate (PC).
[0033]
  A twelfth solving means is characterized in that the refrigerating machine oil is composed of alkylbenzene (AB) in the first to fifth solving means.
[0034]
  In the first solving means and the sixth to twelfth solving means, a refrigerant circuit using carbon dioxide as a refrigerant. (C) As the refrigerating machine oil, an oil that is separated into two phases from the refrigerant in a temperature range of at least −20 ° C. and has a density higher than the refrigerant in the temperature range is used. (3) Oil separator connected to the outlet side of (6) , The refrigerating machine oil separates from the refrigerant and accumulates below the refrigerant. Therefore, refrigeration oil is an oil separator (6) Pull out from the lower end of the evaporator (Five) Compressor without flowing into (2) You can return to In particular, when a refrigerating machine oil such as PAG that is separated from a carbon dioxide refrigerant at −50 ° C. or higher is used, even in a refrigerating apparatus having a lower evaporation temperature, the expander (3) Make sure to separate the refrigerant and refrigeration oil at the outlet side of the (Five) Oil can be prevented from flowing into.
[0035]
  A thirteenth solution means is the compressor according to any one of the first to fifth solution means. (2) And expander (3) But one casing (11) It is provided inside and is integrated.
[0036]
  The fourteenth solution means is the oil separator according to any one of the first to fifth solution means. (6) Oil return passage (45c) Through the compressor (2) It is characterized by being connected to the suction side. In the fourteenth solution, an oil separator (6) Refrigerating machine oil separated from the refrigerant in the oil return passage (45c) Through the compressor (2) Return to the suction side. Therefore, the expander (3) Refrigerating machine oil flowing out of the evaporator (Five) Will not flow into.
[0037]
【The invention's effect】
  From the first12thAccording to this solution, the oil separator (6) is provided on the outlet side of the expander (3) in the refrigerant circuit (C) using carbon dioxide as the refrigerant, and the oil separator is used by specifying the refrigerating machine oil to be used. The refrigerating machine oil separated from the refrigerant in the evaporator (6) can be prevented from flowing from the expander (3) into the evaporator (5). Accordingly, it is possible to prevent the refrigeration capacity from decreasing.
[0038]
  In particular, the aboveAccording to the first to fifth solving means, the centrifugal oil separator (6) This makes it possible to reliably separate the refrigerant and the refrigerating machine oil without complicating the configuration and to remove only the refrigerant from the evaporator. (Five) Therefore, it is possible to reliably prevent a decrease in the refrigerating capacity.
[0039]
  Also, aboveAccording to the sixth solution, since the temperature range is limited to a more preferable range, the refrigeration oil is used as an expander. (3) From evaporator (Five) It is possible to more reliably prevent the refrigerant from flowing into the hood, and to prevent a decrease in the refrigerating capacity.
[0040]
  According to the thirteenth solution, the compressor (2) And expander (3) But one casing (11) Since it is provided inside and integrated, the apparatus can be made compact.
[0041]
  Moreover, according to the fourteenth solution means, the oil separator (6) Oil return passage from (45c) The compressor (2) Connect to the suction side of the oil separator (6) Refrigerating machine oil separated from the refrigerant in the oil return passage (45c) Through compressor (2) The expander is designed to return to the suction side of the (3) Refrigerating machine oil that flows out of the refrigerant from the evaporator (Five) Does not flow into. Therefore, the expander (3) From evaporator (Five) Inflow of refrigerating machine oil and a decrease in refrigeration capacity can be reliably prevented.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.
[0043]
  ImplementationFormThe refrigeration apparatus according to the present invention is configured, for example, as an air conditioner (1) that cools a room. As shown in FIG. 1, the air conditioner (1) includes a refrigerant circuit (C). The refrigerant circuit (C) is configured by connecting a compressor (2), a radiator (4) as a gas cooler, an expander (3) as an expansion mechanism, and an evaporator (5) in order. Closed circuit. This refrigerant circuit (C) has CO as a refrigerant.₂ (Carbon dioxide) is filled.
[0044]
  In the refrigerant circuit (C), the refrigerant circulates to perform a refrigeration cycle. The compressor (2) compresses the sucked refrigerant to a pressure higher than the critical pressure of the refrigerant, that is, a supercritical pressure. Therefore, the refrigeration cycle performed in the refrigerant circuit (C) is a supercritical pressure cycle in which the high pressure is set to the supercritical pressure of the refrigerant. The refrigerant discharged from the compressor (2) is cooled by the radiator (4), expanded by the expander (3), evaporated by the evaporator (5), and then returned to the compressor (2). The operation of each stroke is repeated with the stroke compressed again as one cycle.
[0045]
  The radiator (4) is provided in the middle of the first air passage (P1). The inlet end of the first air passage (P1) opens to the outside of the room. A first fan (F1) is provided on the inlet side of the first air passage (P1). When the first fan (F1) is operated, outdoor air taken in from the inlet end is sent to the radiator (4) as first air in the first air passage (P1). This first air constitutes heated air. On the other hand, the outlet end of the first air passage (P1) opens to the outside of the room. From the outlet end of the first air passage (P1), the first air that has absorbed heat from the refrigerant in the radiator (4) is blown out of the room.
[0046]
  In the radiator (4), the refrigerant circulating through the refrigerant circuit (C) exchanges heat with the first air sent through the first air passage (P1). By heat exchange in the radiator (4), the refrigerant in the refrigerant circuit (C) dissipates heat to the first air and is cooled. The radiator (4) is constituted by, for example, a cross fin type heat exchanger.
[0047]
  The evaporator (5) is provided in the middle of the second air passage (P2). The inlet end of the second air passage (P2) opens into the room. A second fan (F2) is provided on the inlet side of the second air passage (P2). When the second fan (F2) is operated, the indoor air taken in from the inlet end is sent as second air to the evaporator (5) in the second air passage (P2). This second air constitutes the air to be cooled. On the other hand, the outlet end of the second air passage (P2) opens into the room. From the outlet end of the second air passage (P2), the second air cooled in the evaporator (5) is blown into the room.
[0048]
  In the evaporator (5), heat is exchanged between the refrigerant circulating in the refrigerant circuit (C) and the second air sent through the second air passage (P2). Due to the heat exchange in the evaporator (5), the refrigerant in the refrigerant circuit (C) absorbs heat from the second air and evaporates. The evaporator (5) is constituted by, for example, a cross fin type heat exchanger.
[0049]
  The compressor (2) and the expander (3) are provided in one casing (11) and constitute one fluid machine (10). As shown in FIG. 2, the fluid machine (10) includes a compression mechanism section (20) as a compressor (2) that compresses refrigerant and an expansion mechanism section as an expander (3) that expands refrigerant. (30).
[0050]
  The compression mechanism portion (20) of the fluid machine (10) is disposed in the lower portion in the casing (11), and the expansion mechanism portion (30) is disposed in the upper portion in the casing (11). A motor (50) is disposed at the center of the casing (11). The motor (50) includes a stator (51) fixed to the casing (11), and a rotor (52) disposed inside the stator (51).
[0051]
  A drive shaft (60) passes through the rotor (52). The drive shaft (60) has a lower end connected to the compression mechanism (20) and an upper end connected to the expansion mechanism (30). For this reason, the fluid machine (10) of the present embodiment is configured such that the rotational power due to refrigerant expansion of the expansion mechanism section (30) is recovered to the compression power of the compression mechanism section (20).
[0052]
  The compression mechanism section (20) is configured as a so-called swing type rotary compressor. The compression mechanism section (20) includes a cylinder (21), a piston (23) housed in a cylinder chamber (22) of the cylinder (21), and a front head that closes the upper surface of the cylinder chamber (22) ( 24) and a rear head (25) for closing the lower surface of the cylinder chamber (22). The lower end of the drive shaft (60) penetrates the rear head (25) from the front head (24) through the cylinder (21).
[0053]
  The piston (23) is formed in an annular shape, and is rotatably fitted to the eccentric shaft portion (61). The eccentric shaft portion (61) is formed below the drive shaft (60) and is eccentric from the shaft center of the drive shaft (60).
[0054]
  Although not shown, the piston (23) is integrally formed with a blade. The blade is inserted into the cylinder (21) via a bush. The piston (23) swings about the bush as a fulcrum, and reduces the volume in the cylinder chamber (22) to compress the refrigerant.
[0055]
  The cylinder (21) is formed with a refrigerant suction port (2a). The front head (24) has a refrigerant outlet (2b). The front head (24) is provided with a discharge valve (26a) for opening and closing the discharge port (2b) and a valve presser (26b).
[0056]
  On the other hand, the expansion mechanism section (30) is configured as a scroll type expander. The expansion mechanism part (30) includes a fixed scroll (31), a movable scroll (32), and a frame (33). The frame (33) is fixed to the casing (11). The frame (33) partitions the internal space of the casing (11) vertically and insulates the space above and below.
[0057]
  The fixed scroll (31) includes a mirror plate (3a) and a spiral (involute) wrap (3b) formed on the lower surface of the mirror plate (3a). The movable scroll (32) includes a mirror plate (3c) and a spiral (involute) wrap (3d) formed on the upper surface of the mirror plate (3c).
[0058]
  The end plate (3a) of the fixed scroll (31) is fixed to the casing (11). The end plate (3a) partitions the upper side of the frame (33) in the inner space of the casing (11) vertically.
[0059]
  The wrap (3b) of the fixed scroll (31) and the wrap (3d) of the movable scroll (32) mesh with each other. Between the end plate (3a) of the fixed scroll (31) and the end plate (3c) of the movable scroll (32), the working chamber which is an expansion chamber is provided between the contact portions of both wraps (3b, 3d). (3e) is formed.
[0060]
  A refrigerant suction port (3f) is formed at the center of the end plate (3a) of the fixed scroll (31). Further, a refrigerant discharge port (3g) is formed on the outer peripheral side of the both wraps (3b, 3d).
[0061]
  The end plate (3c) of the movable scroll (32) is installed on an annular thrust bearing (34) formed on the upper surface of the frame (33). Further, between the end plate (3c) of the movable scroll (32) and the frame (33), rotation prevention such as an Oldham mechanism is performed so that the movable scroll (32) only revolves with respect to the fixed scroll (31). A member (35) is provided.
[0062]
  A connecting hole (36) for the drive shaft (60) is formed at the center of the movable scroll (32). Specifically, a cylindrical boss portion (37) is formed projecting upward at the center of the upper surface of the end plate (3c) of the movable scroll (32). An opening having the same diameter as the boss hole of the boss portion (37) is formed in the central portion of the end plate (3c). The boss hole and the opening form a connection hole (36) of the drive shaft (60). The boss portion (37) is formed substantially the same as the height of the wrap (3d).
[0063]
  At the upper end portion of the drive shaft (60), there is formed an eccentric shaft portion (62) having a small diameter that penetrates the frame (33) and is eccentric from the shaft center of the drive shaft (60). The eccentric shaft portion (62) is fitted into the connecting hole (36) of the movable scroll (32).
[0064]
  The drive shaft (60) has an oil supply hole (63) formed along the central axis. The oil supply hole (63) communicates with the sliding portions of the compression mechanism portion (20) and the expansion mechanism portion (30) via the oil introduction grooves (63a, 63b). The lower end portion of the drive shaft (60) is configured as a centrifugal oil pump (64), although details are not shown in the figure. The oil supply hole (63) and the oil pump (64) constitute an oil supply means.
[0065]
  An evaporator (5) is connected to the discharge port (3g) of the expansion mechanism section (30) via a refrigerant pipe (43). On the other hand, an evaporator (4) is connected to the suction port (2a) of the compression mechanism section (20) via a refrigerant pipe (43). The refrigerant pipe (43) on the suction side of the compression mechanism section (20) is provided with an accumulator (44), which is omitted in FIG.
[0066]
  In the casing (11), the refrigerant (20) discharged from the compression mechanism (20) is discharged into the lower space (12) of the frame (33) to form a high-pressure atmosphere. A refrigerant pipe (43) is connected to the side of the casing (11), and the refrigerant pipe (43) is connected to the radiator (4). That is, the refrigerant discharged from the compression mechanism section (20) is supplied to the radiator (4).
[0067]
  A radiator (4) is connected to the upper part of the casing (11) via a refrigerant pipe (43). In the casing (11), the refrigerant from the radiator (4) is introduced into the uppermost space (13) above the end plate (3a) of the fixed scroll (31) through the refrigerant pipe (43). The That is, the refrigerant from the radiator (4) is introduced into the working chamber (3e) of the expansion mechanism section (30).
[0068]
  As shown in FIG. 1, an oil separator (6) is connected to the outlet side of the expander (3) in the refrigeration apparatus (1). The oil separator (6) uses a centrifugal oil separator, and the refrigerant flowing out of the expander (3) is separated from the refrigerating machine oil by the oil separator (6). While flowing into (5), the refrigeration oil is sucked into the compressor (2).
[0069]
  Specifically, as shown in FIG. 3, the oil separator (6) includes a cylindrical container (6a) and an introduction pipe connected along the tangential direction of the peripheral wall surface at the top of the container (6a). (6b), a refrigerant outlet pipe (6c) disposed along the vertical direction on the upper surface of the container (6a), and an oil outlet pipe (6d) provided on the bottom surface of the container (6a). The refrigerant pipe (45a) from the expander (3) is connected to the inlet pipe (6b), the refrigerant pipe (45b) to the evaporator (5) is connected to the refrigerant outlet pipe (6c), and the oil outlet pipe An oil return pipe (45c) to the compressor (2) is connected to (6d). The oil return pipe (45c) is connected to the upper part of the accumulator (44) in the refrigerant pipe (43) on the suction side of the compressor (2).
[0070]
  The oil separator (6) must send the refrigerant to the evaporator (5) after separating the refrigerant and oil flowing from the expander (3). In the oil separator (6), both are separated by the difference in density between the refrigerant and the oil, as will be described later. In order to perform oil separation successfully, it is necessary to prevent the oil-rich liquid from being wound up by the gas refrigerant. Therefore, in the oil separator (6), the refrigerant outlet pipe (6c) to the evaporator (5) is provided in contact with the inner wall of the oil separator (6), and the lower end opens into the refrigerant rich liquid. I have to. Thereby, the liquid refrigerant and the gas refrigerant can be supplied to the evaporator (5).
[0071]
  This implementationFormThen, as a refrigerant, CO₂ On the other hand, polyalkylene glycol (PAG) is used for refrigerating machine oil. PAG has the property of separating into two phases with the refrigerant in a temperature range of at least −20 ° C. or higher and depending on the type, PAG separates into two phases with the refrigerant in a temperature range of −50 ° C. or higher. The PAG has a density higher than that of the refrigerant in a temperature range of −50 ° C. to −17 ° C. or higher, and the density is generally higher than that of the refrigerant in the temperature range of the two-phase separation. In other words, in the conventional relationship between the refrigerant and the refrigeration oil, the refrigeration oil is lighter than the refrigerant, but in this embodiment, the refrigeration oil whose density of the refrigerant and the refrigeration oil is reversed in a predetermined temperature range is used. Used.
[0072]
  The graph of FIG.₂ And PAG dissolution characteristics, the vertical axis represents CO₂ The two-phase separation temperature, and the horizontal axis is the oil fraction. This graph shows that refrigerant and oil dissolve below the line segment, while refrigerant and oil separate above the line segment. For example, in order to obtain an oil-rich liquid with an oil content of 30%, it is understood that the temperature should be about 0 ° C. for PAG # 7 and about −30 ° C. for PAG # 9. For PAG # 20 or the like, it may be about −50 ° C. In such a temperature range, the oil separator (6) separates the refrigerant rich liquid and the oil rich liquid (FIG. 3).
[0073]
      -Driving action-
  Next, the operation of the refrigeration apparatus (1) described above will be described.
[0074]
  First, when the motor (50) is driven in the fluid machine (10), the piston (23) in the compression mechanism (20) swings in the cylinder chamber (22), and sucks the refrigerant from the evaporator (5), The refrigerant is compressed. This compressed refrigerant is discharged into the casing (11). The compressed refrigerant flows into the radiator (4) and is radiated to the outside air to be cooled.
[0075]
  The cooled refrigerant is then introduced into the expansion mechanism section (30). That is, the movable scroll (32) revolves with respect to the fixed scroll (31) by driving the motor (50), and the working chamber (3e) performs an expansion action. The cooling refrigerant flows from the uppermost space (13) of the casing (11) into the working chamber (3e) of the expansion mechanism (30) and expands. The expanded refrigerant flows into the evaporator (5), cools the room air and evaporates.
[0076]
  When performing the above operation, the refrigerating machine oil is supplied to the sliding parts of the compression mechanism part (20) and the expansion mechanism part (30) by the rotation of the drive shaft (60). The refrigeration oil contained in the refrigerant flowing out from the expansion mechanism section (30) is separated from the refrigerant in the oil separator (6). Although the PAG differs slightly depending on the type, the density is relatively large, and the density is higher than that of the refrigerant in a temperature range of minus 50 ° C. to minus 17 ° C. or more. Therefore, if the refrigerant oil and the refrigerating machine oil are separated into two phases and the refrigerating machine oil is set to accumulate in the lower part in the container (6a) of the oil separator (6), the refrigerating machine oil will have the oil return pipe (45c). It returns to the compressor (2) and does not flow into the evaporator (5). For this reason, since the refrigeration oil does not give heat to the refrigerant in the evaporator (5), it is possible to prevent the refrigeration capacity from being lowered.
[0077]
      -ImplementationFormEffect of
  In this way, this implementationFormAccording to the present invention, the oil separator (6) is provided on the outlet side of the expander (3), and the refrigerating machine oil separated from the refrigerant in the oil separator (6) by using PAG as the refrigerating machine oil, ) Is returned from the oil return pipe (45c) connected to the lower end of the compressor (2) to the compressor (2), so that the refrigerating machine oil whose temperature has increased in the compressor (2) is transferred from the expander (3) to the evaporator. (5) can be prevented from flowing in, and the refrigeration capacity can be prevented from being lowered.
[0078]
  In other words, since the refrigeration oil is usually lighter than the refrigerant, even if an oil separator (6) is installed on the outlet side of the expander (3), the refrigeration oil floats on the liquid refrigerant and only the refrigeration oil is used. Although it cannot be extracted, this implementationFormThen, at the outlet side of the expander (3), CO₂ By adopting PAG as the refrigerating machine oil having a higher density than the refrigerant, it becomes possible to separate the refrigerant and the refrigerating machine oil. And by doing in this way, it becomes possible to also prevent the fall of the capability by refrigerating machine oil flowing in into an evaporator (5).
[0079]
  In the above embodiment, since the frame (33) insulates the compression mechanism part (20) and the expansion mechanism part (30) in the casing (11), the heat of the compression mechanism part (20) It is difficult to transmit to the oil separator (6) on the downstream side of the expansion mechanism (30), and the frame (33) insulates between the casing (11) of the compressor (2) and the oil separator (6). It acts as a heat insulation means.
[0080]
  Therefore, while the casing (11) of the compression mechanism section (20) has a high temperature close to the discharge temperature, the expansion mechanism section (30) and the oil separator (6) have a low temperature close to the evaporation temperature. The frame (33) as the heat insulating means can prevent heat transfer from the high temperature part to the low temperature part. Therefore, it can prevent that the efficiency of a freezing apparatus falls.
[0081]
      -ImplementationFormVariation of-
  (Modification 1)
  Implementation aboveFormThen, as a refrigerant, CO₂ On the other hand, although PAG is used for the refrigerating machine oil, the refrigerating machine oil of the refrigerant circuit (C) is separated into the above refrigerant and two phases in a temperature range of at least −20 ° C., and −20 ° C. or more. As long as the refrigerating machine oil has a density larger than that of the refrigerant in the temperature range, a material other than the PAG may be used.
[0082]
  For example, polyvinyl ether (PVE), polyol ester (highly stable polyol ester (HS-POE)), polycarbonate (PC), or the like may be used for the refrigerating machine oil. These refrigerating machine oils, as shown in FIG. 5, are in the temperature range of −20 ° C.₂ Therefore, if the evaporation temperature is set appropriately, the above implementation is possible.FormIt is possible to achieve substantially the same effect.
[0083]
  Further, mineral oil or alkylbenzene (AB) may be used for the refrigerating machine oil. These refrigeration oils are CO₂ Implemented in the same way because it does not dissolve in the refrigerantFormIt is possible to achieve almost the same effect.
[0084]
  (Modification 2)
  FIG. 6 shows a first modification of the oil separator (6). The oil separator (6) includes a liquid refrigerant outlet pipe (6c-l) extending upward along the inner surface of the peripheral wall of the container (6a), and a gas refrigerant outlet pipe (6c) connected to the upper surface of the container (6a). -g), and both outlet pipes (6c-l, 6c-g) are joined outside the container (6a). Other parts are configured in the same manner as the oil separator (6) shown in FIG.
[0085]
  As described above, when the liquid refrigerant and the gas refrigerant are separately flowed, the oil-rich liquid is not unnecessarily wound up by the gas refrigerant, so that the oil separation efficiency can be increased. For this reason, it is possible to reliably prevent the oil from flowing into the evaporator (5), and thus it is possible to more reliably suppress a decrease in efficiency.
[0086]
  (Modification 3)
  FIG. 7 shows the oil separator (6) of FIG. 3 in which a refrigerant outlet pipe (6c) is connected to the upper surface of the container (6a). The other parts are the same as in the example of FIG.
[0087]
  In this configuration, when the gas-liquid two-phase refrigerant flows from the expander (3) into the oil separator (6), the refrigerating machine oil and the refrigerant are separated by a swirling flow generated in the oil separator (6). Since the refrigeration oil is heavier than the refrigerant, it accumulates under the container (6a) and is discharged from the oil outlet pipe (6d). On the other hand, as the gas refrigerant turns, the liquid refrigerant is caught in the gas refrigerant and flows out of the refrigerant outlet pipe (6c) together with the gas refrigerant. Therefore, although it is a simple structure, it can prevent that oil flows into an evaporator (5) and can prevent a reduction in efficiency.
[0088]
  (Modification 4)
  FIG. 8 shows a third modification of the oil separator (6). This oil separator (6) is provided with a baffle plate (6e) inside a container (6a), and the upper part of the container (6a) has a double structure. The introduction pipe (6b) is connected to the baffle plate (6e) and penetrates the container (6a). The introduction pipe (6b) is disposed along the tangential direction of the baffle plate (6e), and the oil separator (6) is configured in a centrifugal manner. Further, the refrigerant outlet pipe (6c) is connected to the central portion of the upper surface of the container (6a). The oil outlet pipe (6d) is connected to the central portion of the bottom surface of the container (6a) as in the example of FIG.
[0089]
  In the case of this example, when the refrigerant is introduced into the oil separator (6), the same effect as that of providing the refrigerant outlet pipe (6c) on the entire circumference of the inner wall of the container (6a) can be obtained. That is, the refrigerant rich liquid is caught in the gas refrigerant and flows out through the entire gap between the container (6a) and the baffle plate (6e), and the oil rich liquid is discharged from the oil outlet pipe (6d). .
[0090]
  (Modification 5)
  FIG. 9 shows a gas refrigerant circulation hole (6e-h) formed in the upper part of the baffle plate (6e) in the oil separator (6) of FIG. 8, and the gas refrigerant flows out from the circulation hole (6e-h). It is what I did. That is, in the configuration almost the same as that in FIG. 8, separate passages for the gas refrigerant and the liquid refrigerant are secured. If the baffle plate (6e) is not provided with a flow hole (6e-h), the liquid-rich refrigerant may be entrained with the gas through the gap between the container (6a) and the baffle plate (6e). On the other hand, the oil separation efficiency can be increased. Therefore, it is possible to reliably prevent the oil from flowing into the evaporator (5), and thus it is possible to more reliably suppress a decrease in efficiency.
[0091]
  (Modification 6)
  FIG. 10 shows that the refrigerant outlet pipe (6c) is bent in a “U” shape inside the container (6a), and the gas inlet is arranged at the upper part of the container (6a), and at the lower part of the refrigerant outlet pipe (6c). A liquid refrigerant inlet hole (6c-h) is formed so that the liquid flows from there. In this way, when the gas refrigerant flows out from the refrigerant outlet pipe (6c), the liquid refrigerant is sucked into the pipe from the inlet hole (6c-h) and flows out together with the gas refrigerant to the evaporator (5). The hole diameter of the inlet hole (6c-h) may be designed so that gas and liquid flow in appropriate amounts according to the dryness of the refrigerant.
[0092]
  Even in this case, the refrigeration oil returns to the suction side of the compressor (2) and does not flow to the evaporator (5), thus preventing a decrease in efficiency.it can.
[0093]
Other Embodiments of the Invention
  The present invention may be configured as follows with respect to the above embodiment.
[0094]
  For example, the above implementationFormIn the above, the case of using the fluid machine (10) in which the compressor (2) and the expander (3) are integrated has been described.FormThen, the compressor (2) and the expander (3) are not necessarily integrated.
[0095]
  Also implementedFormIn FIG. 1, a centrifugal oil separator (6) is used, but another type of oil separator (6) may be used.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view of a fluid machine used in the refrigeration apparatus of FIG.
3 is a structural diagram of an oil separator used in the refrigeration apparatus of FIG. 1. FIG.
[Figure 4] CO₂ It is a 1st graph which shows the melt | dissolution characteristic of a refrigerant | coolant and refrigerator oil.
[Figure 5] CO₂ It is a 2nd graph which shows the melt | dissolution characteristic of a refrigerant | coolant and refrigerator oil.
FIG. 6 is a structural diagram showing a first modification of the oil separator.
FIG. 7 is a structural diagram showing a second modification of the oil separator.
FIG. 8 is a structural diagram showing a third modification of the oil separator.
FIG. 9 is a structural diagram showing a fourth modification of the oil separator.
FIG. 10 is a structural diagram showing a fifth modification of the oil separator.is there.
[Explanation of symbols]
(1) Air conditioner
(2) Compressor
(3) Expander
(4) Heatsink
(5) Evaporator
(6) Oil separator
(6a) Container
(6b) Introduction pipe
(6c) Refrigerant outlet pipe
(6d) Oil outlet pipe
(6f) Separation membrane
(10) Fluid machinery
(11) Casing
(20) Compression mechanism
(21) Cylinder
(23) Piston
(30) Expansion mechanism
(31) Fixed scroll
(32) Movable scroll
(33) Frame
(50) Motor
(60) Drive shaft
(63) Lubrication hole (lubrication means)
(64) Oil pump (oil supply means)
(C) Refrigerant circuit

Claims (14)

The compressor (2), the radiator (4), the expander (3), and the evaporator (5) are provided with a refrigerant circuit (C) connected in order, and the refrigerant circuit (C) is filled with carbon dioxide as a refrigerant. Refrigeration equipment,
An oil separator (6) is connected between the outlet side of the expander (3) and the evaporator (5) inlet side through which the refrigeration oil contained in the refrigerant discharged from the compressor (2) flows.
The refrigerating machine oil of the refrigerant circuit (C) is composed of refrigerating machine oil that separates into two phases with the refrigerant at a temperature range of at least −20 ° C. and has a density higher than that of the refrigerant in the temperature range ,
The oil separator (6) is constituted by a centrifugal oil separator (6) ,
The oil separator (6) includes an inlet pipe (6b) connected in a tangential direction to the peripheral wall of the vertical cylindrical container (6a) , and a refrigerant outlet pipe connected to the upper surface of the container (6a) ( 6c), and an oil outlet pipe (6d) connected to the bottom surface of the container (6a) ,
In the oil separator (6) , the refrigerant outlet pipe (6c) is arranged in the vertical direction along the inner surface of the peripheral wall of the container (6a) , and the lower end of the refrigerant outlet pipe (6c) is arranged at the height of the container (6a) . A refrigerating apparatus configured to be located in an intermediate portion in a vertical direction and open into a liquid refrigerant . A compressor (2) , a radiator (4) , an expander (3), and an evaporator (5) are provided with a refrigerant circuit (C) connected in order , and the refrigerant circuit (C) is filled with carbon dioxide as a refrigerant. Refrigeration equipment,
An oil separator (6) is connected between the outlet side of the expander (3) and the inlet side of the evaporator (5) for injecting refrigeration oil contained in the refrigerant discharged from the compressor (2) ,
The refrigerating machine oil of the refrigerant circuit (C) is composed of refrigerating machine oil that separates into two phases with the refrigerant in a temperature range of at least −20 ° C. or higher and whose density is larger than that of the refrigerant in the temperature range,
The oil separator (6) is constituted by a centrifugal oil separator (6) ,
The oil separator (6) includes an inlet pipe (6b) connected in a tangential direction to the peripheral wall of the vertical cylindrical container (6a) , and a refrigerant outlet pipe connected to the upper surface of the container (6a) ( 6c), and an oil outlet pipe (6d) connected to the bottom surface of the container (6a) ,
Oil separator (6), the refrigerant outlet pipe (6c) is a container connected to a gas refrigerant outlet pipe to the upper surface of (6a) (6c-g), the vertical direction along the inner surface of the peripheral wall of the container (6a) its lower end while being positioned is because the container height direction liquid refrigerant outlet pipe opening into the liquid refrigerant located in the middle part of (6a) (6c-l), the gas refrigerant outlet pipe (6C- A refrigeration apparatus characterized in that g) and the liquid refrigerant outlet pipe (6c-l) merge outside the container (6a) . A compressor (2) , a radiator (4) , an expander (3), and an evaporator (5) are provided with a refrigerant circuit (C) connected in order , and the refrigerant circuit (C) is filled with carbon dioxide as a refrigerant. Refrigeration equipment,
An oil separator (6) is connected between the outlet side of the expander (3) and the inlet side of the evaporator (5) for injecting refrigeration oil contained in the refrigerant discharged from the compressor (2) ,
The refrigerating machine oil of the refrigerant circuit (C) is composed of refrigerating machine oil that separates into two phases with the refrigerant in a temperature range of at least −20 ° C. or higher and whose density is larger than that of the refrigerant in the temperature range,
The oil separator (6) is constituted by a centrifugal oil separator (6) ,
The oil separator (6) includes an inlet pipe (6b) connected in a tangential direction to the peripheral wall of the vertical cylindrical container (6a) , and a refrigerant outlet pipe connected to the upper surface of the container (6a) ( 6c), and an oil outlet pipe (6d) connected to the bottom surface of the container (6a) ,
The oil separator (6) includes a baffle plate (6e) having a double structure at the top of the container (6a) in the container (6a) ,
The refrigerant outlet pipe (6c) is connected to the upper surface of the container (6a) , and the introduction pipe (6b) is connected to the baffle plate (6e) through the peripheral wall of the container (6a). Refrigeration equipment. The refrigeration apparatus according to claim 3, wherein the oil separator (6) includes a gas refrigerant circulation hole (6e-h) through which the gas refrigerant circulates in an upper part of the baffle plate (6e) . A compressor (2) , a radiator (4) , an expander (3), and an evaporator (5) are provided with a refrigerant circuit (C) connected in order , and the refrigerant circuit (C) is filled with carbon dioxide as a refrigerant. Refrigeration equipment,
An oil separator (6) is connected between the outlet side of the expander (3) and the inlet side of the evaporator (5) for injecting refrigeration oil contained in the refrigerant discharged from the compressor (2) ,
The refrigerating machine oil of the refrigerant circuit (C) is composed of refrigerating machine oil that separates into two phases with the refrigerant in a temperature range of at least −20 ° C. or higher and whose density is larger than that of the refrigerant in the temperature range,
The oil separator (6) is constituted by a centrifugal oil separator (6) ,
The oil separator (6) includes an inlet pipe (6b) connected in a tangential direction to the peripheral wall of the vertical cylindrical container (6a) , and a refrigerant outlet pipe connected to the upper surface of the container (6a) ( 6c), and an oil outlet pipe (6d) connected to the bottom surface of the container (6a) ,
Oil separator (6), together with the refrigerant outlet pipe (6c) is formed in a shape bent in a U-shape in the container (6a), the upper end of the container the refrigerant outlet pipe in the (6a) (6c) Is formed at the inlet of the gas refrigerant, and a liquid refrigerant inlet hole (6c-h) is formed below the U-shaped outlet pipe . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is separated into a two-phase carbon dioxide refrigerant in a temperature range of -50 ° C or higher . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is composed of polyalkylene glycol . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is made of polyvinyl ether . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is composed of mineral oil . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is composed of a polyol ester . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is made of polycarbonate . The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating machine oil is composed of alkylbenzene . The refrigeration apparatus according to any one of claims 1 to 5, wherein the compressor (2) and the expander (3) are provided in one casing (11) and integrated . The refrigerating apparatus according to any one of claims 1 to 5, wherein the oil separator (6) is connected to the suction side of the compressor (2) via an oil return passage (45c) .

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