JP4055902B2 - Refrigeration equipment with an expander - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration apparatus that is used in an air conditioner, a refrigerator, or the like and includes an expander that recovers power of fluid energy in the expansion process of the refrigerant, and is particularly suitable for an apparatus that uses carbon dioxide as a refrigerant. .
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a vapor compression refrigeration cycle used in an air conditioner, a refrigerator, or the like is known in which an expander is used to improve the COP (coefficient of performance) of the refrigeration cycle. 1 is described.
[0003]
In this prior art, the mainstream refrigerant is decompressed while converting the expansion energy of the mainstream refrigerant that is expanded by the expander into mechanical energy (expanding work is performed), and the second compressor is operated by the converted mechanical energy. As a result, the mainstream refrigerant flowing out of the heat exchanger lowers its enthalpy while changing the isentropy, so that the refrigerating capacity is greatly reduced even when the pressure in the evaporator rises. In addition to preventing this, COP is improved. This type of system can be applied particularly to a refrigeration cycle using a natural refrigerant used in a supercritical region such as carbon dioxide.
[0004]
[Patent Document 1]
JP 2000-329416 A
[Problems to be solved by the invention]
In the refrigeration cycle described in Patent Document 1 above, a scroll-type expander that converts expansion energy into mechanical energy (rotational energy) in a substantially cylindrical housing, and operation by rotational energy obtained by the expander. A cylindrical machine room in which a scroll type compression mechanism is housed is formed.
[0005]
However, in this conventional technology, sufficient consideration is not given to the lubrication of the sliding parts of the scroll type expander and the compressor, which has a significant effect on the energy recovery efficiency, and the efficiency decreases due to the friction loss of the sliding parts. There was a problem of reliability degradation due to wear of sliding parts. Moreover, the energy recovery device which consists of a 1st compressor and an expander and a compressor is provided in the refrigerating cycle, and lubrication of these sliding parts is covered with the lubricating oil with which each apparatus was filled. The lubricating oil possessed by the compressor and the lubricating oil possessed by the energy recovery unit become imbalanced, and a problem in reliability occurs regardless of which lubricating oil is insufficient.
[0006]
An object of the present invention is to obtain a refrigeration apparatus including an expander that can reliably lubricate sliding portions of the expander and each compressor.
[0007]
Another object of the present invention is to obtain a refrigeration apparatus equipped with an expander capable of improving the COP of the refrigeration cycle and improving the reliability of a positive displacement expander.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a sealed container having lubricating oil stored at the bottom, and an expansion that is immersed in the lubricating oil in the sealed container and converts the expansion energy of the refrigerant into mechanical energy. And the expansion In machine A sub-compressor which is disposed in a stack and immersed in the lubricating oil in the sealed container and driven by the expander; The crankshaft of the sub compressor and the expander has an oil supply passage for supplying lubricating oil to each bearing sliding portion, and the refrigerant pressurized by the sub compressor is discharged into the space in the sealed container. An expansion / compression system;
Airtight container with lubricating oil stored at the bottom And immersed in the lubricating oil in the sealed container, and the pressurized refrigerant is discharged into the space in the sealed container. The main compressor and its motor;
A first flow path for circulating the high-pressure refrigerant compressed by the main compressor to the sub-compressor via a radiator, an expansion valve, and an evaporator;
A second flow path for circulating the refrigerant pressurized by the sub-compressor in the closed container of the expansion / compression system to the main compressor;
A third flow path that branches from the first flow path and causes a part of the refrigerant flowing out of the radiator to flow to the expander;
The opening position of the discharge port on the main compressor side in the first flow path, In the sealed container The main compressor hermetically sealed container is positioned above the lubricating oil surface Inside space Open to
The opening position on the side of the expansion / compression system in the second flow path, In the sealed container A closed container of the expansion / compression system so as to be positioned above the lubricating oil surface Inside space The refrigeration apparatus is characterized in that it is opened.
[0011]
The present invention also includes a sealed container storing lubricating oil at the bottom, an expander that is immersed in the lubricating oil in the sealed container and converts expansion energy of the refrigerant into mechanical energy, and the expansion In machine A sub-compressor which is disposed in a stack and immersed in the lubricating oil in the sealed container and driven by the expander; The crankshaft of the sub compressor and the expander has an oil supply passage for supplying lubricating oil to each bearing sliding portion, and the refrigerant pressurized by the sub compressor is discharged into the space in the sealed container. An expansion / compression system;
Airtight container with lubricating oil stored at the bottom And immersed in the lubricating oil in the sealed container, and the pressurized refrigerant is discharged into the space in the sealed container. The main compressor and its motor;
A first flow path for circulating the high-pressure refrigerant compressed by the main compressor to the sub-compressor via a radiator, an expansion valve, and an evaporator;
A second flow path for circulating the refrigerant pressurized by the sub-compressor in the sealed container of the expansion / compression system into the sealed container of the main compressor;
A third flow path that branches from the first flow path and causes a part of the refrigerant flowing out of the radiator to flow to the expander;
The opening position of the discharge port on the main compressor side in the first flow path, In the sealed container The main compressor hermetically sealed container is positioned above the lubricating oil surface Inside space Open to
The refrigerating apparatus is characterized in that the suction pipe has an opening at an opening position of the main compressor so as to face an upper surface of the lubricating oil in the airtight container, and an oil recovery small hole is provided in the suction pipe.
[0012]
It is preferable to use carbon dioxide as the refrigerant of the refrigeration apparatus, and the expander is preferably a rolling piston expander.
[0013]
As described above, in the case where the internal pressure is maintained at the discharge pressure of the sub-compressor and the closed container for the expansion / compression system that stores the lubricating oil is provided, the lubricating oil stored in the closed container by the flow of the discharge gas is used. It becomes possible to return to the main compressor.
[0014]
In particular, the main compressor is equipped with a sealed container, and a discharge pipe to the radiator side is provided above the compression mechanism on the side of the main compressor sealed container, and at the top of the expansion / compression system sealed container to the main compressor side. By providing this discharge pipe, it is possible to prevent the lubricating oil in each sealed container from being biased to either one by utilizing the oil level rise prevention function due to the flow of gas, maintaining a good lubrication state, Performance and reliability can be improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a refrigeration cycle showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing an example of a compression / expansion system (a positive displacement fluid machine) used in the embodiment of FIG. 1, and FIG. 2 is a cross-sectional view taken along the line AA, and FIG. 4 is a cross-sectional view taken along the line BB in FIG.
[0016]
1 to 4, a compression / expansion system (positive displacement fluid machine) 1 includes an expander 2 (represented by the symbol EX) that converts expansion energy of a working fluid in a refrigeration cycle into mechanical energy, and the converted mechanical energy. The sub-compressor (sub-compressor) 3 (represented by the symbol SC) that performs the work is arranged, and the expander 2 and the sub-compressor 3 are arranged in a single sealed container 5 and are arranged via the crankshaft 4. Are connected and stored.
[0017]
A refrigeration system 24 shown in FIG. 1 includes a compression / expansion system 1 between a radiator 25 and an evaporator 26. In the sealed container 27a, a main compressor (symbol MC) 27 of the refrigeration system 24 and a drive motor (symbol M) for driving the main compressor are housed. Reference numeral 27b denotes a suction pipe, 27c denotes a discharge pipe, and 29 denotes a suction accumulator having a function of storing liquid refrigerant.
[0018]
As for the flow of the refrigerant, the high-temperature and high-pressure refrigerant discharged from the main compressor 27 enters the radiator 25 via the discharge pipe 27c and is radiated to lower the temperature. The refrigerant discharged from the radiator 25 passes through the upstream expansion valve 28 for adapting the design pressure ratio of the expander 2 to the operating pressure ratio of the refrigeration cycle, enters the expander 2 from the inflow pipe 11, and expands here. The expansion energy is converted into mechanical energy. Thereafter, the refrigerant becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant and is discharged from the outflow pipe 12. The refrigerant exiting the expander 2 enters the evaporator 26 and absorbs heat and gas, is sucked into the subcompressor 3 from the suction pipe 18, is pressurized in the subcompressor 3, and is discharged into the sealed container 5. The air is discharged from the discharge pipe 19 attached to the upper side of the sealed container 5 to the outside (main compressor side). The refrigerant discharged from the sub-compressor 3 returns to the main compressor 27 through the suction accumulator 29 and is compressed again to become a high-temperature / high-pressure gas refrigerant. The refrigerant is discharged into the main-compressor sealed container 27a. The discharge pipe 27c provided above the compressor section 27a flows out to the external cycle. The above cycle is repeated to produce a freezing action.
[0019]
Reference numeral 20 denotes lubricating oil stored in the sealed container 5 and the sealed container 27a. The bypass expansion valve 28b is attached to a circuit that bypasses the expander 2, and performs a flow rate (pressure) adjustment operation when the operating condition of the refrigeration cycle is changed.
[0020]
As described above, with the configuration including the positive displacement fluid machine 1, the expansion process becomes isentropic change, and the refrigeration effect is increased and the refrigeration capacity is increased. In addition, since fluid energy in the expansion process is converted into mechanical energy by the expander 2 and the power is recovered by driving the sub-compressor 3, work for gas compression can be reduced and COP of the refrigeration system 24 can be improved. . Here, the airtight container 5 storing the lubricating oil 20 of the positive displacement fluid machine (expansion / compression system) 1 and the airtight container 27a storing the lubricating oil 20 of the main compressor 27 are both compressed. There is an atmosphere of gas discharged from the machine, and there is a flow of gas flowing out from each sealed container. Therefore, by setting the opening positions of the discharge ports of the discharge pipe 19 and the discharge pipe 27c above the oil level position necessary for lubrication of the fluid machine accommodated in each closed container, either one of the closed containers is set. When the lubricating oil 20 is biased and the oil level rises, the oil is taken out by the flow of the discharged gas and returned to the other sealed container. Therefore, the bias of the lubricating oil between each sealed container is automatically adjusted, the lubrication state of the fluid machine sliding part can be kept good, and the performance and reliability of the refrigeration system equipped with the expander can be improved. It becomes.
[0021]
Next, as a positive displacement fluid machine (expansion / compression system) 1 used in the present invention, a rotary type is taken as an example, and the structure and operation will be described with reference to FIGS.
As shown in FIGS. 2 and 3, in the expander 2, both ends of the cylinder 8 are closed by a lower bearing 6 that also serves as a shaft support for the crankshaft 4 and a partition plate 7. The cylinder 8 has a cylindrical inner peripheral surface 8a formed at the center. The crankshaft 4 is formed with an eccentric portion 4a at a portion corresponding to the cylindrical inner peripheral surface 8a of the cylinder 8, and a cylindrical inner peripheral surface to which the bearing metal 9b of the roller portion 9a of the swing piston 9 is fitted. It is inserted so that it can rotate. A plate-like vane portion 9c is integrally formed on the cylindrical outer peripheral surface of the roller portion 9a. A cylindrical hole 8b having a central axis parallel to the central axis of the cylindrical inner peripheral surface 8a is formed outside the cylindrical inner peripheral surface 8a of the cylinder 8, and the cylinder 8 center side of the cylindrical hole 8b and The opposite side communicates with the cylindrical inner peripheral surface 8a of the cylinder 8 and the escape hole portion 8c provided outside the cylindrical hole portion 8b.
[0022]
The vane portion 9c of the oscillating piston 9 is inserted into the cylindrical hole portion 8b and the escape hole portion 8c, but can slide between the vane portion 9c and the cylindrical hole portion 8b on the plane portion of the vane portion 9c. A shoe 10 having a flat surface portion in contact with the cylindrical surface portion and a cylindrical surface portion slidably in contact with the cylindrical surface portion of the cylindrical hole portion 8b is incorporated in such a manner as to sandwich the vane portion 9c. As a result, the vane portion 9c performs a reciprocating motion through the central axis of the cylindrical hole portion 8b and a swinging motion about the central axis, and the shoe 10 performs a swinging motion about the central axis of the cylindrical hole portion 8b. The tip of the vane portion 9c moves in the escape hole portion 8c and does not interfere with the cylinder 8. The inflow pipe 11 attached to the sealed container 5 is connected to an inflow passage 8 d that opens in the cylindrical hole portion 8 b of the cylinder 8.
[0023]
The adjustment of the inflow timing of the working fluid, which is a feature of the expander, is performed by forming a high-pressure working fluid flowing from the inflow pipe 11 through the inflow passage 8d of the cylinder 8 in the shoe 10 on the inflow passage 8d side. This is easily realized by setting a communication state between the inflow hole 10a and the inflow groove 9d formed in the side surface portion of the vane portion 9c with which the shoe 10 in which the inflow hole 10a is formed abuts (details will be described later).
[0024]
On the other hand, as shown in FIGS. 2 and 4, the positive displacement sub-compressor (blower) 3 is closed at both ends of the cylinder 15 by the upper bearing 14 that also serves as the shaft support of the crankshaft 4 and the partition plate 7. ing. The cylinder 15 has a cylindrical inner peripheral surface 15a formed at the center. The crankshaft 4 is formed with another eccentric portion 4b at the portion corresponding to the cylindrical inner peripheral surface 15a of the cylinder 15 (the rotational phase between the eccentric portion 4a on the expander 2 side and this eccentric portion 4b is 180 °). The roller bearing is attached to the inner peripheral surface of the cylindrical roller 16 so as to be rotatable. A plate-like vane 17 is pressed against the cylindrical outer peripheral surface of the roller 16 by a vane spring 17a. On the outside of the cylindrical inner peripheral surface 15a of the cylinder 15, a vane groove 15b through which the vane 17 can reciprocate, a relief hole portion 15c for preventing interference between the cylinder 15 and the vane 17, and the other end portion of the vane spring 17a are fitted. Thus, a spring hole 15d to be mounted is formed.
[0025]
The suction pipe 18 attached to the sealed container 5 is connected to the suction passage 15e of the cylinder 15, and the refrigerant gas sucked from the suction pipe 18 enters the cylinder 15 through the suction passage 15e, and is cranked. As the shaft 4 rotates, the roller 16 moves by performing an eccentric rotational movement along the cylindrical inner peripheral surface 15 a of the cylinder 15. The refrigerant gas further passes through a discharge notch 15f formed in a shape in which a part of the cylindrical inner peripheral surface 15a of the cylinder 15 is cut out, and is discharged into the sealed container 5 from a discharge port 14a formed in the upper bearing 14. Then, it flows out from the discharge pipe 19 attached to the upper side surface portion of the sealed container 5 to the external refrigeration cycle.
[0026]
Since the lubricating oil 20 is stored at the bottom of the sealed container 5 and most of the expander 2 and the positive displacement sub-compressor 3 are immersed in the lubricating oil 20, an oil supply path is provided to each sliding portion. The lubricating oil can be easily guided through. Further, in order to forcibly supply oil to the bearing sliding portions (each bearing portion of the crankshaft 4), an oil supply piece 21 is attached to the lower end portion of the crankshaft 4, and the crankshaft is passed through an oil supply passage 4c formed in the crankshaft 4. Lubricating oil is supplied to each bearing sliding part by the centrifugal pump action by rotation of 4.
[0027]
Further, the balance of the rotating system is taken by a balance weight 22 attached to the upper end portion of the crankshaft 4, and the balance weight 22 is surrounded by a balance weight cover 23.
The expander 2 and the displacement subcompressor (subcompressor) 3 having the above-described configuration are fastened and fixed by the assembly bolts 13 in a stacked state, and the cylinder of the displacement subcompressor (blower) 3 is fixed. The outer peripheral portion 15 is fitted and fixed to the inner periphery of the sealed container 5.
[0028]
Next, the operation of the expander 2 will be described with reference to FIGS. FIG. 5 is an operation explanatory view of the expander showing the inflow process of the working fluid for each crankshaft rotation angle, and FIG. 6 is an operation explanatory view showing the inflow completion and outflow start states of the working fluid in the expander.
[0029]
FIG. 5 shows the positional relationship of the swing piston 9 in the cylinder 8 at every crankshaft rotation angle of 90 °. The vane portion 9c of the swing piston 9 is at the top dead center position (the vane portion is the most in the cylinder 8). When the rotation angle θ is 0 °, the crankshaft 4 rotates clockwise.
[0030]
First, in a state where the rotation angle is 0 °, the inflow passage 8d of the cylinder 8 and the inflow hole 10a of the shoe 10 are partially communicated with each other, and are formed in the inflow hole 10a of the shoe 10 and the vane portion 9c of the swing piston 9. The inflow groove 9d is also communicated, but the end a of the inflow groove 9d on the cylinder cylindrical inner peripheral surface 8a side is closed by the shoe 10, so that the high pressure at the expansion process inlet of the vapor compression refrigeration cycle. The working fluid is blocked from flowing into the cylinder 8. On the other hand, since the outflow passage 8e of the cylinder 8 communicates with the inside of the cylinder 8, the working fluid is in a low pressure state corresponding to the expansion process outlet. From this state, when the crankshaft 4 rotates clockwise, the vane portion 9c protrudes into the cylinder 8 and the inflow groove 9d starts to communicate with the inside of the cylinder, so that high-pressure working fluid begins to flow into the cylinder 8, Due to the pressure difference in the cylinder 8, mechanical energy for rotating the crankshaft 4 clockwise is generated.
[0031]
In a state where the rotation angle is 90 °, the flow area of the connecting portion b between the cylinder inflow passage 8d and the shoe inflow hole 10a is increased by the swing of the shoe 10, and thus the inflow of the working fluid is promoted.
Further, in the state of the rotation angle of 180 ° rotated 90 °, the inflow passage 8d of the cylinder 8 and the inflow hole 10a of the shoe 10 are partially communicated as in the state of the rotation angle of 0 °, but the cylinder of the vane portion 9c. The reciprocating motion toward the cylindrical inner peripheral surface 8a side cuts off the communication between the shoe inflow hole 10a and the vane inflow groove 9d, and the volume of the working chamber expands in a state where the inflow of high-pressure working fluid is blocked. The fluid expands and generates mechanical energy.
[0032]
In the state of the rotation angle of 270 °, the shoe inflow hole 10a and the vane inflow groove 9d begin to communicate with each other. However, the inflow passage 8d of the cylinder 8 and the inflow hole 10a of the shoe 10 now have a rotation angle of 90 °. The working fluid further expands and continues to generate mechanical energy in a state in which the communication between the two is cut off because of the swinging motion in the opposite direction to the state.
When the rotation further proceeds, the outflow passage 8e of the cylinder 8 communicates with the inside of the cylinder 8, and the initial rotation angle is 0 °. By repeating the above operation, the fluid energy of the working fluid is converted into mechanical energy.
[0033]
In general, the value of the design volume ratio of the positive displacement expander is determined by the type of working fluid in the refrigeration system and its operating conditions (pressure ratio). The design volume ratio Vrex of the expander 2 of the present embodiment is defined such that the volume into which the high-pressure working fluid flows (inflow completion volume) is Vi, and the expansion end volume (outflow start volume) is Vo.
Vrex = Vo / Vi
It is represented by
[0034]
FIG. 6 is an operation diagram showing the completion of the inflow of the working fluid and the start of the outflow in the expander. The inflow completion state is a state immediately after the communication between the vane inflow groove 9d and the shoe inflow hole 10a is cut off. In this embodiment, the rotation angle of the crankshaft corresponds to 137 ° (volume Vi = 0.242, However, when the crankshaft rotation angle is 0 °, the volume is 1. The outflow start state is a state immediately before the expansion operation space in the cylinder 8 communicates with the outflow passage 8e, and corresponds to a crankshaft rotation angle of 317 ° (volume Vo = 0.98). The design volume ratio Vrex of the expander 2 of the present invention is obtained from the ratio of both volumes, and the value is
Vrex = 0.98 / 0.242 = 4.05
(The design conditions are as follows: working fluid: carbon dioxide (R744), suction pressure Ps = 2.65 MPa, discharge pressure Pd = 8 MPa, see FIG. 7).
[0035]
5 and 6, it is possible to easily change the crankshaft rotation angle at which the inflow is completed, that is, the inflow completion volume, by adjusting the length of the vane inflow groove 9d, and the outflow starts depending on the position of the outflow passage 8e. Since the volume can also be changed, it can be seen that the design volume ratio Vrex can be easily changed. As a result, the swing type expander with a vane (rolling piston type expander) is easier to design than the expander with a unique design volume ratio such as screw type or scroll type. In addition to this, a significant reduction in size and cost can be achieved. Furthermore, for example, by forming a plurality of outflow passages 8e in the cylinder 8 and selectively switching the outflow passages, a plurality of design volume ratios can be realized with a single expander. This increases the system efficiency of the refrigeration and air conditioning equipment.
[0036]
FIG. 7 is a diagram showing a refrigeration cycle on the Mollier diagram when carbon dioxide (R744), which is a natural refrigerant, is used as the working fluid.
Note that carbon dioxide (R744) as a refrigerant is a natural refrigerant, and has a global warming potential (GWP) that is one-thousandth that of a fluorocarbon refrigerant, which is excellent in terms of global environmental conservation. On the other hand, since the critical temperature is as low as about 31 ° C, the operating pressure on the high pressure side exceeds the critical pressure (about 7 MPa) under the normal operating conditions of the refrigeration air conditioner. There is a disadvantage that the theoretical COP (coefficient of performance) is low. However, since the loss of the expansion process is larger than that of the fluorocarbon refrigerant, R744 can be expected to greatly improve the COP by recovering the power of the expansion process. Therefore, it is considered that the development of a positive displacement fluid machine equipped with a highly efficient and highly reliable expander holds the key to the practical application of a refrigeration apparatus using the refrigerant R744. Even if the present invention is applied to a refrigeration apparatus using a chlorofluorocarbon refrigerant, the improvement ratio is somewhat reduced, but the COP can be improved. Here, a refrigeration cycle using the refrigerant R744 will be described as an example.
[0037]
In the Mollier diagram of FIG. 7, BC is a compression process by the main compressor 27, CD is a heat release process by the radiator (gas cooler) 25, and DE is an expansion process of the expander 2, FIG. The expansion operation described is performed to convert the expansion energy into mechanical energy. E-A shows the evaporation process by the evaporator 26, and A-B shows the compression process by the sub-compressor (blower) 3 driven by the expander 2.
[0038]
As is clear from FIG. 7, by providing the expansion / compression system (positive displacement fluid machine) 1 of this embodiment, the expansion process becomes an isentropic change (DE), and the isoenthalpy without an expander is obtained. Compared with the change (indicated by a broken line), the refrigeration effect increases by Δiex, and the refrigeration capacity increases. Further, by converting expansion energy into mechanical energy by the expander 2 and driving the positive displacement sub-compressor to recover the power, the work required to compress the unit mass of gas is reduced from Δiad to Δiad ′ and COP It becomes possible to improve.
[0039]
A starting method of the expansion / compression system (positive displacement fluid machine) 1 of the present embodiment will be described. First, when the main compressor 28 is started, the discharge pipe 19 side of the sub-compressor 3 first becomes negative pressure, and torque for rotating the drive shaft 4 is generated. Next, pressure acts on the inflow pipe 11 of the expander 2 to rotationally drive the expander 2, enabling self-sustained activation. If necessary, the expansion / compression system may be activated by attaching an activation device such as a motor.
In the present embodiment, the rolling piston type is described as an example of the positive displacement sub-compressor, but the present invention is not limited to this, and other types of positive displacement sub-compressors such as a scroll type may be used. Applicable.
[0040]
Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a configuration diagram of the refrigeration cycle, and FIG. 9 is an enlarged view of a main part of a suction pipe portion to the main compressor shown in FIG. In these drawings, the same reference numerals as those in FIGS. 1 to 4 denote the same or corresponding parts, and they perform the same function.
[0041]
This embodiment is an example of a low-pressure chamber system in which the pressure inside the sealed container 27 a of the main compressor 27 is kept at the suction pressure of the main compressor 27. A suction pipe 27b to the main compressor 27 is provided in the sealed container 27a, and its opening (suction end) is located above the oil surface 20a of the lubricating oil 20 stored in the sealed container. Reference numeral 27b ′ shown in FIG. 9 denotes an oil recovery small hole formed in the suction pipe 27b. The oil recovery small hole 27b ′ is provided at the upper limit position of the appropriate oil level in the main compressor hermetic container 27a below the opening. Yes.
[0042]
When the oil level 20a in the closed container 27a rises and reaches the oil recovery small hole 27b ′, the pressure in the suction pipe 27b is reduced by the flow of the suction gas indicated by the arrow in FIG. 9, and the lubricating oil 20 is supplied to the oil recovery small hole 27b. Since the oil flows into the suction pipe 27b through ', the rise of the oil level 20a is suppressed. The lubricating oil 20 sucked into the main compressor 27 together with the suction gas passes through the circuit of the refrigeration cycle, and is a sealed container in which a compression / expansion system (a positive displacement fluid machine) 1 including the expander 2 and the sub compressor 3 is stored. Then, the deviation of the lubricating oil between the sealed container 27a and the sealed container 5 is automatically adjusted. As a result, the lubrication state of the fluid machine sliding portion can be maintained well, and the performance and reliability of the refrigeration apparatus including the expander can be improved. Therefore, practical application of a refrigeration air conditioning system using carbon dioxide (R744), which is a natural refrigerant, is promoted and can contribute to prevention of global warming.
[0043]
【The invention's effect】
According to the present invention, a sub-compressor that is driven by an expander and compresses the refrigerant to flow to the main compressor is provided, the expander and the sub-compressor are housed inside, and the internal pressure becomes the discharge pressure of the sub-compressor. Since it is configured to include a sealed container for an expansion / compression system that retains and stores lubricating oil, and a sealed container for main compressor that stores a main compressor and stores lubricating oil therein, the flow of working fluid As a result, the rise of the oil level in each sealed container is regulated, and the lubricating oil is recirculated. As a result, the bias of the lubricating oil between the closed containers is automatically adjusted, the lubrication state of the fluid machine sliding portion can be kept good, and the performance and reliability of the refrigeration system including the expander can be improved. Is possible.
[0044]
In addition, according to the present invention, since the sub-compressor is driven by the expansion energy of the refrigerant, the COP of the refrigeration cycle can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a refrigeration cycle showing an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing an example of a compression / expansion system used in the embodiment of FIG.
3 is a cross-sectional view taken along the line AA in FIG.
4 is a cross-sectional view taken along the line BB in FIG.
FIG. 5 is an operation explanatory view of the expander showing the inflow process of the working fluid for each crankshaft rotation angle.
FIG. 6 is an operation explanatory view showing the completion of inflow of working fluid and the start of outflow in the expander.
FIG. 7 is a diagram showing a refrigeration cycle using carbon dioxide on the Mollier diagram.
FIG. 8 is a refrigeration cycle configuration diagram showing another embodiment of the present invention.
FIG. 9 is an enlarged view of a main part of a suction pipe portion to the main compressor shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Expansion / compression system (displacement type fluid machine), 2 ... Expander, 3 ... Displacement type sub compressor (sub compressor), 4 ... Crankshaft, 4a ... Eccentric part, 4b ... Eccentric part, 4c ... Oil supply passage DESCRIPTION OF SYMBOLS 5 ... Sealed container, 6 ... Lower bearing, 7 ... Partition plate, 8 ... Cylinder, 8a ... Cylindrical inner peripheral surface, 8b ... Cylindrical hole part, 8c ... Escape hole part, 8d ... Inflow passage, 8e ... Outflow passage, DESCRIPTION OF SYMBOLS 9 ... Swing piston, 9a ... Roller part, 9b ... Bearing metal, 9c ... Vane part, 9d ... Inflow groove, 10 ... Shoe, 10a ... Inflow hole, 11 ... Inflow pipe, 12 ... Outflow pipe, 13 ... Assembly bolt, DESCRIPTION OF SYMBOLS 14 ... Upper bearing, 15 ... Cylinder, 15a ... Cylindrical inner peripheral surface, 15b ... Vane groove, 15c ... Escape hole part, 15d ... Spring hole part, 15e ... Suction passage, 15f ... Discharge notch, 16 ... Roller, 17 ... Vane, 17a ... Vane spring, 18 ... Suction pipe, 19 ... Discharge pie 20 ... Lubricating oil, 20a ... Oil level, 21 ... Refueling piece, 22 ... Balance weight, 23 ... Balance weight cover, 24 ... Refrigerating system, 25 ... Radiator, 26 ... Evaporator, 27 ... Main compressor, 27a ... Sealed container, 27b ... suction pipe, 27b '... oil recovery small hole, 27c ... discharge pipe, 28 ... pre-stage expansion valve, 28b ... bypass expansion valve, 29 ... suction accumulator.

Claims (3)

A sealed container in which the bottom stores lubricating oil, this is immersed in housed in the lubricating oil in the closed container, an expander for converting expansion energy of the refrigerant into mechanical energy, the sealed and stacked on the expander A sub-compressor that is immersed in the lubricating oil in the container and driven by the expander, and an oil supply passage that supplies the lubricating oil to each bearing sliding portion to the crankshaft of the sub-compressor and the expander DOO anda expansion / compression system Ru discharged into the space of the refrigerant that has been pressurized by the auxiliary compressor is in said closed container,
A main container that stores the lubricating oil in the bottom , and is immersed in the lubricating oil in the sealed container and stored therein, and discharges the pressurized refrigerant into the space in the sealed container, and its motor;
A first flow path for circulating the high-pressure refrigerant compressed by the main compressor to the sub-compressor via a radiator, an expansion valve, and an evaporator;
A second flow path for circulating the refrigerant pressurized by the sub-compressor in the closed container of the expansion / compression system to the main compressor;
A third flow path that branches from the first flow path and causes a part of the refrigerant flowing out of the radiator to flow to the expander;
The opening position of the discharge port on the main compressor side in the first flow path is opened in the space in the sealed container of the main compressor so as to be positioned above the lubricating oil surface in the sealed container,
The opening position on the expansion / compression system side in the second flow path is opened in a space in the sealed container of the expansion / compression system so as to be positioned above the lubricating oil surface in the sealed container . Refrigeration equipment. A sealed container in which the bottom stores lubricating oil, this is immersed in housed in the lubricating oil in the closed container, an expander for converting expansion energy of the refrigerant into mechanical energy, the sealed and stacked on the expander A sub-compressor that is immersed in the lubricating oil in the container and driven by the expander, and an oil supply passage that supplies the lubricating oil to each bearing sliding portion to the crankshaft of the sub-compressor and the expander DOO anda expansion / compression system Ru discharged into the space of the refrigerant that has been pressurized by the auxiliary compressor is in said closed container,
A main container that stores the lubricating oil in the bottom , and is immersed in the lubricating oil in the sealed container and stored therein, and discharges the pressurized refrigerant into the space in the sealed container, and its motor;
A first flow path for circulating the high-pressure refrigerant compressed by the main compressor to the sub-compressor via a radiator, an expansion valve, and an evaporator;
A second flow path for circulating the refrigerant pressurized by the sub-compressor in the sealed container of the expansion / compression system into the sealed container of the main compressor;
A third flow path that branches from the first flow path and causes a part of the refrigerant flowing out of the radiator to flow to the expander;
The opening position of the discharge port on the main compressor side in the first flow path is opened in the space in the sealed container of the main compressor so as to be positioned above the lubricating oil surface in the sealed container,
A refrigerating apparatus characterized in that an opening position of a suction pipe of the main compressor is arranged so as to face upward from a lubricating oil surface in the airtight container, and an oil recovery small hole is provided in the suction pipe.   The refrigerating apparatus according to claim 1 or 2, wherein the refrigerant of the refrigerating apparatus is carbon dioxide, and the expander is a rolling piston expander.

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