JP2008133968A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply the sufficient amount of lubricating oil to an expander in a refrigerating cycle device equipped with a compressor and the expander and to attain miniaturization or weight reduction of the device. <P>SOLUTION: The refrigerating cycle device 10 comprises a refrigerant circuit 11 where the compressor 1, a radiator 2, the expander 3 and an evaporator 5 are connected in this order, and an oil supply pipe 7 serving for communication between an oil sump of the compressor 1 and an oil sump of the expander 3. The oil supply pipe 7 is provided with a cooler 6 for cooling the lubricating oil, and a valve 8 for adjusting the flow rate of the lubricating oil. Inlet side piping 57 of the expander 3 is provided with a temperature sensor 81. A controller 80 controls the opening of the valve 8 based on the inlet refrigerant temperature of the expander 3. In the refrigerating cycle device equipped with the expander, the sufficient amount of lubricating oil is thereby supplied to the expander while attaining miniaturization or weight reduction of the device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus including a compressor and an expander.

  In a so-called vapor compression refrigeration cycle apparatus, an apparatus having an expander instead of an expansion valve is known. In this type of refrigeration cycle apparatus, by using an expander, the expansion energy in the process of expansion of the refrigerant can be recovered in the form of electric power or power, and the efficiency of the cycle can be improved by the amount of the recovered energy. it can.

In a refrigeration cycle apparatus equipped with an expander, lubricating oil is required not only for the compressor but also for the expander. In view of this, a refrigeration cycle apparatus has been proposed in which an oil separator is provided in the refrigerant circuit and the lubricating oil separated by the oil separator is supplied to the expander. For example, the following Patent Document 1 discloses a refrigeration air conditioner provided with an oil separator provided between a compressor and a radiator, and an oil feed pipe connecting the oil separator and an inlet side pipe of an expander. Is disclosed.
JP 2001-141315 A

  However, in the refrigeration air conditioner disclosed in Patent Document 1, the number of parts of the device is increased by the amount of the oil separator. In addition, since a new oil separator is additionally provided, a new installation space is required, resulting in an increase in size and weight of the apparatus. In particular, when the refrigerant is used in a supercritical state, the oil separator is required to have sufficient pressure resistance, and thus the weight of the apparatus cannot be avoided.

  The present invention has been made in view of such a point, and an object of the present invention is to supply a sufficient amount of lubricating oil to the expander in the refrigeration cycle apparatus including the expander. The aim is to reduce the size or weight.

  A refrigeration cycle apparatus according to the present invention communicates a refrigerant circuit in which a compressor, a radiator, an expander, and an evaporator are connected in order, the compressor and the expander, and supplies lubricating oil in the compressor. An oil supply passage for supplying to the expander and a cooling device for cooling the lubricating oil in the oil supply passage are provided.

  According to the refrigeration cycle apparatus, the lubricating oil stored in the compressor is supplied to the expander through the oil supply passage. Therefore, an oil separator becomes unnecessary. The high-temperature lubricating oil from the compressor is cooled by the cooling device when flowing through the oil supply passage. Therefore, the high-temperature lubricating oil does not flow into the expander as it is, and the temperature of the refrigerant before expansion does not increase excessively. Therefore, lubricating oil can be supplied from the compressor to the expander without causing a reduction in COP. As a result, it is possible to sufficiently supply lubricating oil to the expander and to reduce the size or weight of the device.

  It is preferable that the compressor and the expander each include a reservoir that stores lubricating oil, and the oil supply passage communicates the reservoir of the compressor and the reservoir of the expander.

  Thus, the lubricating oil can be supplied from the compressor to the expander with a simple configuration.

  The compressor includes a compression mechanism that compresses the refrigerant, and a compressor shell that covers the compression mechanism and discharges the refrigerant compressed by the compression mechanism, and the expander expands the refrigerant. And an expander shell that covers the expansion mechanism and stores the refrigerant before being decompressed by the expansion mechanism. The compressor and the storage part of the expander are respectively the compressor shell and the expander shell. It is preferable that the oil supply passage is formed of a pipe having one end connected to the compressor shell and the other end connected to the expander shell.

  In the refrigeration cycle apparatus, the lubricating oil in the compressor and the expander has a higher pressure than the compression mechanism and the expansion mechanism. Therefore, the lubricating oil is satisfactorily supplied from the lubricating oil reservoir to the sliding portions of the compression mechanism and the expansion mechanism.

  The cooling device performs heat exchange for directly or indirectly heat-exchanging a part of the refrigerant in the low-pressure part from the expander to the compressor through the evaporator in the refrigerant circuit and the lubricating oil in the oil supply passage. It is preferable to have a device.

  As a result, the heat radiation from the lubricating oil can be recovered by the refrigerant in the refrigerant circuit, so that the heating efficiency can be improved and the evaporator can be made compact.

  The refrigeration cycle apparatus may include a transport device that transports the lubricating oil in the oil supply passage.

  As a result, the lubricating oil can be forcibly conveyed by the conveying device, so even if the pressure difference between the compressor side and the expander side of the oil supply passage is small, A sufficient amount of lubricating oil can be supplied.

  It is preferable that the refrigeration cycle apparatus includes a flow rate adjusting device that adjusts the flow rate of the lubricating oil in the oil supply passage.

  As a result, an appropriate amount of lubricating oil can always be supplied to the expander.

  The refrigeration cycle apparatus preferably includes a temperature sensor that detects a refrigerant temperature on the inlet side of the expander, and a controller that controls the flow rate adjusting device based on a temperature detected by the temperature sensor.

  This makes it possible to adjust the supply amount of the lubricating oil based on the refrigerant temperature on the inlet side of the expander, and to achieve both high efficiency of the refrigeration cycle and sufficient supply of the lubricant oil to the expander. it can.

  The expander includes an expander whose operation capacity can be freely adjusted, and the refrigeration cycle apparatus includes an operation capacity detection device that detects an operation capacity of the expander, and the flow rate adjustment device based on the operation capacity of the expander. And a controller for controlling.

  Thereby, the supply amount of the lubricating oil can be adjusted based on the operating capacity of the expander, and the improvement in efficiency of the refrigeration cycle and the sufficient supply of the lubricant oil to the expander can be made highly compatible.

  In the refrigeration cycle apparatus, a refrigerant in a high pressure portion from the compressor in the refrigerant circuit to the expander through the radiator may be in a supercritical state.

  As described above, according to the present invention, the lubricating oil can be sufficiently supplied to the expander, and the refrigeration cycle apparatus can be reduced in size or weight.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the refrigeration cycle apparatus 10 according to the first embodiment includes a refrigerant circuit 11 in which a compressor 1, a radiator 2, an expander 3, and an evaporator 5 are connected in order. In addition, the refrigeration cycle apparatus 10 includes an oil supply pipe 7 that allows the compressor 1 and the expander 3 to communicate with each other. The oil supply pipe 7 is provided with a cooler 6 and a valve 8. The valve 8 is a valve whose opening degree can be freely adjusted.

The refrigerant charged in the refrigerant circuit 11 is a refrigerant that becomes a supercritical state in a high-pressure portion (portion from the compressor 1 through the radiator 2 to the expander 3) during operation. The refrigerant circuit 11 of the present embodiment is filled with carbon dioxide (CO ₂ ) as such a refrigerant. However, the type of refrigerant is not particularly limited.

  As shown in FIG. 2, the compressor 1 according to the present embodiment is a rotary compressor. However, the compressor 1 is not limited to the rotary type, and may be another type of compressor (for example, a scroll compressor). The compressor 1 includes a sealed container 21 constituting a compressor shell, and an electric motor 24 and a compression mechanism 25 housed in the sealed container 21.

  The compressor 1 is a so-called high-pressure dome type compressor, and a refrigerant on the high-pressure side of the refrigerant circuit 11 (hereinafter simply referred to as a high-pressure refrigerant) is stored inside the sealed container 21. In the present embodiment, the sealed container 21 is a so-called vertically long container having a vertical length longer than a horizontal length. However, the shape, dimensions, and the like of the sealed container 21 are not particularly limited. A terminal 43 to which a power cable or the like is connected is fixed to the upper wall of the sealed container 21. A discharge pipe 31 is connected to the upper wall of the sealed container 21. A suction pipe 32 is connected to the side wall of the sealed container 21, and an oil supply pipe 7 is connected to the bottom of the side wall of the sealed container 21.

  The electric motor 24 includes a stator 22 fixed to the inner wall of the hermetic container 21 and a rotor 23 disposed inside the stator 22. On the outer peripheral side of the stator 22, a plurality of notches 41 serving as refrigerant flow paths are formed. A gap 42 is provided between the stator 22 and the rotor 23.

  A shaft 26 is fixed to the center of the rotor 23. The shaft 26 extends below the rotor 23. An eccentric portion 26 a that is offset from the axis L of the shaft 26 is provided at the lower portion of the shaft 26. The upper part of the shaft 26 above the eccentric part 26 a is supported by the upper bearing member 27, and the lower part of the eccentric part 26 a is supported by the lower bearing member 28.

  A cylinder 30 is disposed between the upper bearing member 27 and the lower bearing member 28. An annular roller 29 is accommodated in the cylinder 30, and an eccentric portion 26 a is accommodated in the roller 29. In the cylinder 30, a vane 33 that contacts the roller 29 and a spring 34 that biases the vane 33 toward the roller 29 are provided.

  The upper bearing member 27 is formed with a suction hole 35 for guiding the suction refrigerant from the suction pipe 32 into the cylinder 30 and a discharge hole 36 for discharging the refrigerant compressed in the cylinder 30 to the internal space of the sealed container 21. ing.

  The bottom of the sealed container 21 forms an oil reservoir 37 that stores lubricating oil. The oil supply pipe 7 opens toward the oil reservoir 37. Although not shown, an oil pump 38 that pumps up the lubricating oil in the oil reservoir 37 is provided at the lower end of the shaft 26. An oil supply hole (not shown) for supplying the lubricating oil pumped up by the oil pump 38 to the sliding portion is formed inside the shaft 26.

  As shown in FIG. 3, the expander 3 according to this embodiment is a two-stage rotary expander that expands the refrigerant in two stages. However, the type of the expander 3 is not limited at all. The expander 3 may be a single-stage rotary expander or another type of expander (for example, a scroll expander).

  The expander 3 includes a sealed container 51 constituting an expander shell, and a generator 52 and an expansion mechanism 55 accommodated in the sealed container 51. That is, the expander 3 according to the present embodiment is an expander with a built-in generator 52. The expander 3 is a so-called high-pressure dome type expander, and high-pressure refrigerant is stored inside the sealed container 51. The sealed container 51 is a vertically long container, like the sealed container 21 of the compressor 1. However, the shape, dimensions, and the like of the sealed container 51 are not limited at all. A terminal 56 to which an electric cable or the like (not shown) is connected is fixed to the upper wall of the sealed container 51. An inlet side pipe 57 is connected to the upper wall of the sealed container 51. The outlet side pipe 57 is connected to the side wall of the sealed container 51, and the oil supply pipe 7 is connected to the bottom of the side wall of the sealed container 51.

  The generator 52 includes a stator 53 fixed to the inner wall of the hermetic container 51 and a rotor 54 arranged inside the stator 53. A shaft 59 is fixed to the center of the rotor 54. The shaft 59 extends upward and downward from the rotor 54, respectively.

  A first eccentric portion 61 and a second eccentric portion 62 that are offset from the axis of the shaft 59 are provided on the upper side of the shaft 59. The lower portion of the first eccentric portion 61 of the shaft 59 is supported by the lower bearing member 65 via the bearing 63. A first cylinder 66 is provided on the lower bearing member 65. A first roller 71 is accommodated in the first cylinder 66, and a first eccentric portion 61 is disposed in the first roller 71. An intermediate plate 67 is provided above the first cylinder 66, and a second cylinder 68 is disposed on the intermediate plate 67. A second roller 72 is accommodated in the second cylinder 68, and a second eccentric portion 62 is disposed in the second roller 72. An upper bearing member 69 is provided on the second roller 72. The upper end portion of the shaft 59 is supported by the upper bearing member 69 via the bearing 64. A block 70 is provided on the upper bearing member 69.

  The lower bearing member 65 is formed with a suction hole 73 that communicates the internal space of the sealed container 51 with the inside of the first cylinder 66. The intermediate plate 67 is formed with a communication hole 74 that communicates the inside of the first cylinder 66 and the inside of the second cylinder 68. A discharge hole 75 connected to the second cylinder 68 is formed in the upper bearing member 69. A discharge hole 76 that connects the discharge hole 75 and the outlet side pipe 58 is formed in the block 70.

  The bottom of the sealed container 51 forms an oil reservoir 77 that stores lubricating oil. The oil supply pipe 7 opens toward the oil reservoir 77. Similar to the shaft 26 of the compressor 1, an oil pump 78 for pumping up lubricating oil is also provided at the lower end of the shaft 59 of the expander 3. Further, an oil supply hole (not shown) for supplying the lubricating oil pumped up by the oil pump 78 to the sliding portion is formed inside the shaft 59.

  In the refrigerant circuit 11 (refer FIG. 1), the structure of the heat radiator 2 and the evaporator 5 is not limited at all. For example, an air-cooled or water-cooled heat exchanger may be used as the radiator 2 or the evaporator 5.

  In the present embodiment, the cooler 6 cools the lubricating oil by an external cooling source. However, the cooling source is not limited at all. The cooler 6 may be, for example, an air-cooled cooler or a water-cooled cooler.

  As shown in FIG. 1, the inlet side pipe 57 of the expander 3 is provided with a temperature sensor 81 that detects the refrigerant temperature. The temperature sensor 81 may be any sensor that substantially detects the refrigerant temperature. Therefore, the temperature sensor 81 may directly detect the refrigerant temperature in the inlet side pipe 57, or indirectly detect the refrigerant temperature by detecting the wall surface temperature of the inlet side pipe 57, or the like. May be. Moreover, the temperature sensor 81 should just detect the inlet refrigerant temperature of the expander 3, and may be provided in the expander 3 itself.

  The refrigeration cycle apparatus 10 is provided with a controller 80. The controller 80 receives the detection signal of the temperature sensor 81 and controls the opening degree of the valve 8. Of course, the controller 80 does not have to be a dedicated controller provided for controlling the valve 8 and may control the compressor 1 and the like.

  Next, the operation of the refrigeration cycle apparatus 10 will be described. In the refrigerant circuit 11, the refrigerant discharged from the compressor 1 radiates heat with the radiator 2, expands with the expander 3, evaporates with the evaporator 5, and then sucked into the compressor 1.

  In the compressor 1 (see FIG. 2), the electric motor 24 is driven, and the roller 29 rotates in the cylinder 30 as the shaft 26 rotates. As a result, the refrigerant is sucked into the cylinder 30 of the compression mechanism 25 from the suction pipe 32, and the refrigerant is compressed in the cylinder 30. The compressed high-pressure refrigerant is discharged into the space in the sealed container 21 through the discharge hole 36 and then discharged from the discharge pipe 31.

  In the expander (see FIG. 3), the high-pressure refrigerant is sucked into the sealed container 51 through the inlet side pipe 57. The high-pressure refrigerant flows into the first cylinder 66 through the suction hole 73 and expands in the first cylinder 66. At this time, the first roller 71 is rotated by the expansion force of the refrigerant. The refrigerant expanded in the first cylinder 66 flows into the second cylinder 68 through the communication hole 74 and further expands in the second cylinder 68. At this time, the second roller 72 is rotated by the expansion force of the refrigerant. Then, the low-pressure refrigerant expanded in the second cylinder 68 is discharged from the outlet side pipe 58 through the discharge hole 75 and the discharge hole 76.

  When the first roller 71 and the second roller 72 rotate as described above, the first eccentric portion 61 and the second eccentric portion 62 in the first roller 71 and the second roller 72 rotate, and the shaft 59 also rotates accordingly. To do. As a result, the rotor 54 of the generator 52 rotates and power is generated. That is, the expansion energy of the refrigerant is recovered as electric power.

  During operation of the refrigeration cycle apparatus 10, the internal pressure of the sealed container 21 of the compressor 1 is higher than the internal pressure of the sealed container 51 of the expander 3. Therefore, due to the internal pressure difference between the compressor 1 and the expander 3, the lubricating oil in the oil reservoir 37 of the compressor 1 flows into the oil reservoir 77 of the expander 3 through the oil supply pipe 7. At this time, the lubricating oil flowing through the oil supply pipe 7 is cooled in the cooler 6. The flow rate of the oil supply pipe 7, that is, the amount of lubricating oil flowing into the expander 3 can be adjusted by adjusting the opening of the valve 8 of the oil supply pipe 7.

  The controller 80 controls the opening degree of the valve 8 based on the inlet refrigerant temperature of the expander 3. For example, the controller 80 may adjust the inflow amount of the lubricating oil so that the internal temperature of the expander 3 does not increase or decrease too much. In this embodiment, the controller 80 controls the opening degree of the valve 8 so that the inlet refrigerant temperature becomes a predetermined value. For example, the controller 80 decreases the opening degree of the valve 8 when the inlet refrigerant temperature of the expander 3 is equal to or higher than a predetermined value, and increases the opening degree of the valve 8 when the inlet refrigerant temperature is lower than the predetermined value.

  As described above, according to the present embodiment, the oil supply pipe 7 that connects the compressor 1 and the expander 3 is provided, and the lubricating oil in the compressor 1 is supplied to the expander 3 through the oil supply pipe 7. It is not necessary to separately provide an oil separator in the refrigerant circuit 11. Therefore, the number of parts can be reduced and the cost can be reduced as much as the oil separator is unnecessary. Further, since the oil supply pipe 7 is provided with the cooler 6, it is possible to prevent the high-temperature lubricating oil in the compressor 1 from flowing into the expander 3 as it is. Therefore, it is possible to avoid an excessive increase in the temperature of the refrigerant before expansion, and to suppress a decrease in evaporator capacity. Therefore, an increase in the load on the compressor 1 can be suppressed, and a decrease in COP can be suppressed. As a result, the lubricating oil can be sufficiently supplied to the expander 3 and the refrigeration cycle apparatus 10 can be reduced in size or weight.

  Since the oil reservoir 37 is provided in the compressor 1, the oil reservoir 77 is provided in the expander 3, and the oil reservoirs 37, 77 are communicated with each other via the oil supply pipe 7, the compressor 1 has a simple configuration. Can supply lubricating oil to the expander 3.

  According to the present embodiment, the compressor 1 and the expander 3 are both high-pressure dome types, and the lubricating oil in the compressor 1 and the expander 3 is more than the sliding portions of the compression mechanism 25 and the expansion mechanism 55. High pressure. Therefore, the lubricating oil is satisfactorily supplied from the oil reservoirs 37 and 77 to the sliding portions of the compression mechanism 25 and the expansion mechanism 55.

  Further, according to the present embodiment, since the oil supply pipe 7 is provided with the valve 8 whose opening degree can be adjusted, the supply amount of the lubricating oil to the expander 3 can be freely adjusted. Moreover, the refrigerant temperature before expansion can be controlled by adjusting the opening degree of the valve 8 based on the inlet refrigerant temperature of the expander 3. Therefore, a decrease in the evaporator capacity can be suppressed, and an increase in the load on the compressor 1 can be suppressed. Therefore, the COP of the refrigeration cycle apparatus 10 can be improved regardless of fluctuations in the operating state.

  Further, according to the present embodiment, the internal pressure of the compressor 1 and the internal pressure of the expander 3 can be balanced by appropriately adjusting the opening degree of the valve 8. For example, the difference between the internal pressure of the compressor 1 and the internal pressure of the expander 3 can be maintained at a predetermined value by adjusting the opening of the valve 8. Therefore, a refrigerant pipe (equal pressure line) that connects the compressor 1 and the expander 3 is not particularly required.

(Modification)
In the above embodiment, the controller 80 controls the opening degree of the valve 8 based on the inlet refrigerant temperature of the expander 3. However, the control executed by the controller 80 is not limited to the above control. For example, as shown in FIG. 4, a rotation speed detection sensor 82 that detects the rotation speed of the expander 3 may be provided, and the opening degree of the valve 8 may be controlled based on the rotation speed of the expander 3. For example, the controller 80 increases the opening degree of the valve 8 when the rotation speed of the expander 3 is greater than or equal to a predetermined value, and decreases the opening degree of the valve 8 when the rotation speed is less than the predetermined value. As a result, a sufficient amount of lubricating oil can always be supplied in accordance with the rotational speed, and the cycle efficiency can be improved.

  Note that controlling the rotational speed of the expander 3 means controlling the operating capacity of the expander 3. Here, the method of controlling the operating capacity of the expander 3 is not limited to the method of controlling the rotational speed. For example, when the expander 3 includes a plurality of expansion mechanisms that are parallel to each other, the overall operating capacity of the expander 3 can be controlled by adjusting the number of operating the plurality of expansion mechanisms. The expander 3 may be composed of a plurality of expanders connected in parallel to each other. In this case as well, the overall operating capacity of the expander 3 can be controlled by adjusting the number of expander units.

(Second Embodiment)
As shown in FIG. 5, 2nd Embodiment adds the change to the cooler 6 of the oil supply pipe | tube 7 in the refrigerating-cycle apparatus 10 of 1st Embodiment. The cooler 6 according to the present embodiment cools the lubricating oil in the oil supply pipe 7 with the low-pressure refrigerant in the refrigerant circuit 11.

  Specifically, the cooler 6 of this embodiment is provided between the expander 3 and the evaporator 5. The cooler 6 is a so-called liquid-liquid heat exchanger that directly exchanges heat between the lubricating oil and the low-pressure refrigerant. Although the specific form of the cooler 6 is not limited at all, for example, a double tube heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, or the like can be suitably used. Further, the cooler 6 can also be configured by joining the oil supply pipe 7 and the refrigerant pipe without using a dedicated heat exchanger.

  Since other configurations are the same as those of the first embodiment, description thereof will be omitted. In FIG. 5, the temperature sensor 81 and the controller 80 are not shown.

  According to the present embodiment, no external cooling source is required for cooling the lubricating oil in the oil supply pipe 7. Therefore, as a whole refrigeration cycle apparatus 10, the number of parts can be reduced and energy can be saved.

  In addition, the refrigerant discharged from the expander 3 is preliminarily heated before the evaporator 5. Therefore, the amount of heat exchange required for the evaporator 5 can be reduced, and the evaporator 5 can be made compact. Moreover, the low pressure side pressure of the refrigerant cycle can be increased, and the load on the compressor 1 can be reduced. Therefore, COP can be improved.

(Third embodiment)
As shown in FIG. 6, the third embodiment is also a modification of the cooler 6 of the oil supply pipe 7 in the refrigeration cycle apparatus 10 of the first embodiment. The cooler 6 according to this embodiment also cools the lubricating oil in the oil supply pipe 7 using the low-pressure refrigerant in the refrigerant circuit 11.

  On the other hand, this embodiment differs from the second embodiment in that the cooler 6 is configured to indirectly exchange heat between the lubricating oil and the low-pressure refrigerant. Specifically, the evaporator 5 of the present embodiment includes a so-called air heat exchanger that exchanges heat between air and a refrigerant, and the cooler 6 is air before being cooled by the evaporator 5 or after being cooled. And an air heat exchanger for exchanging heat with the lubricating oil. In the refrigeration cycle apparatus 10 of this embodiment, a blower 9 common to the evaporator 5 and the cooler 6 is provided. However, it goes without saying that a blower may be provided for each of the evaporator 5 and the cooler 6.

  Since other configurations are the same as those of the first embodiment, description thereof will be omitted. In FIG. 6, the temperature sensor 81 and the controller 80 are not shown.

  Also in this embodiment, the effect of 1st Embodiment and the effect of 2nd Embodiment can be acquired.

(Fourth embodiment)
In the first to third embodiments, the oil supply pipe 7 is provided with the valve 8. However, as shown in FIG. 7, the oil supply pipe 7 may be provided with an oil pump 8 a instead of the valve 8 (or together with the valve 8). The controller 80 may control the oil pump 8a based on the inlet refrigerant temperature or the operating capacity of the expander 3.

  By providing the oil pump 8a in the oil supply pipe 7, the flow rate of the lubricating oil in the oil supply pipe 7 can be increased even when the pressure difference between the compressor 1 and the expander 3 is small. Therefore, a sufficient amount of lubricating oil can always be supplied to the expander 3. Moreover, it becomes possible to control the flow rate of the lubricating oil widely.

(Other embodiments)
If it is not necessary to control the flow rate of the lubricating oil in the oil supply pipe 7, a throttle mechanism such as a capillary tube may be provided instead of the valve 8 whose opening degree can be adjusted. If the pressure loss in the oil supply pipe 7 is in an appropriate range (a range in which an appropriate amount of lubricating oil can be supplied to the expander 3), the valve 8 can be omitted.

  The type of the oil supply pipe 7 is not limited at all. The oil supply pipe 7 may be formed of a flexible pipe so that the oil supply pipe 7 is not easily damaged by vibration of the compressor 1 or the expander 3. Further, the length and shape of the oil supply pipe 7 are not limited at all. However, from the viewpoint of reducing the pressure loss of the oil supply pipe 7, the length of the oil supply pipe 7 is preferably short, and is preferably a straight pipe.

  In the said embodiment, the compressor 1 and the expander 3 were high pressure dome types. However, so long as the performance of the lubricating oil is not deteriorated, the compressor 1 and the expander 3 may be of a so-called low pressure dome type in which a low pressure refrigerant is stored.

  The refrigerant charged in the refrigerant circuit 11 is not limited to a refrigerant that is in a supercritical state in the high-pressure portion of the refrigerant circuit 11, and may be a refrigerant that does not enter a supercritical state in the high-pressure portion.

  As described above, the present invention is useful for a refrigeration cycle apparatus including a compressor and an expander.

Refrigerant circuit diagram of the refrigeration cycle apparatus according to the first embodiment Compressor longitudinal section Vertical section of expander Refrigerant circuit diagram according to a modification of the first embodiment Refrigerant circuit diagram of refrigeration cycle apparatus according to the second embodiment Refrigerant circuit diagram of refrigeration cycle apparatus according to the third embodiment Refrigerant circuit diagram of refrigeration cycle apparatus according to the fourth embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 3 Expander 5 Evaporator 6 Cooler (cooling device, heat exchange device)
7 Oil supply pipe (oil supply passage)
8 valves (flow control device)
8a Oil pump (conveying device)
10 Refrigeration cycle equipment 11 Refrigerant circuit 21 Airtight container (compressor shell)
25 Compression mechanism 37, 77 Oil reservoir (reservoir)
51 Airtight container (expander shell)
55 Expansion Mechanism 80 Controller 81 Temperature Sensor 82 Rotational Speed Detection Sensor (Operating Capacity Detection Device)

Claims (9)

A refrigerant circuit in which a compressor, a radiator, an expander, and an evaporator are sequentially connected;
An oil supply passage for communicating the compressor and the expander, and supplying lubricating oil in the compressor to the expander;
A cooling device for cooling the lubricating oil in the oil supply passage;
A refrigeration cycle apparatus comprising: Each of the compressor and the expander includes a storage unit that stores lubricating oil,
The refrigeration cycle apparatus according to claim 1, wherein the oil supply passage communicates a storage part of the compressor and a storage part of the expander. The compressor includes a compression mechanism that compresses the refrigerant, and a compressor shell that covers the compression mechanism and from which the refrigerant compressed by the compression mechanism is discharged,
The expander includes an expansion mechanism that expands the refrigerant, and an expander shell that covers the expansion mechanism and stores the refrigerant before being decompressed by the expansion mechanism,
The compressor and the expander reservoir are provided inside the compressor shell and the expander shell, respectively.
The refrigeration cycle apparatus according to claim 2, wherein the oil supply passage includes a pipe having one end connected to the compressor shell and the other end connected to the expander shell.   The cooling device performs heat exchange for directly or indirectly heat-exchanging a part of the refrigerant in the low-pressure part from the expander to the compressor through the evaporator in the refrigerant circuit and the lubricating oil in the oil supply passage. The refrigeration cycle apparatus according to any one of claims 1 to 3, further comprising an apparatus.   The refrigeration cycle apparatus according to any one of claims 1 to 4, further comprising a transport device that transports the lubricating oil in the oil supply passage.   The refrigeration cycle apparatus according to any one of claims 1 to 5, further comprising a flow rate adjusting device that adjusts a flow rate of the lubricating oil in the oil supply passage. A temperature sensor for detecting a refrigerant temperature on the inlet side of the expander;
A controller for controlling the flow rate adjusting device based on a temperature detected by the temperature sensor;
The refrigeration cycle apparatus according to claim 6, comprising: The expander is an expander whose operation capacity can be freely adjusted,
An operating capacity detection device for detecting the operating capacity of the expander;
A controller for controlling the flow rate adjusting device based on the operating capacity of the expander;
The refrigeration cycle apparatus according to claim 6, comprising: The refrigeration cycle apparatus according to any one of claims 1 to 8, wherein a refrigerant in a high-pressure portion from the compressor to the expander through the radiator in the refrigerant circuit is in a supercritical state.

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