JP4775206B2 - Refrigerant circuit with expander - Google Patents

Description

  The present invention relates to a refrigerant circuit including an expander that generates power by expanding a high-pressure fluid and recovers energy, and more specifically, prevents an over-expansion phenomenon of a high-pressure fluid that causes a decrease in energy recovery efficiency. Related to the configuration to be performed.

  The conventional refrigeration cycle is configured by sequentially connecting a compressor, a radiator, an expansion valve, and a heat absorber. The refrigerant circulating in the refrigeration cycle is compressed by a compressor to become high temperature and high pressure, cooled by a radiator, then adiabatically expanded by an expansion valve and depressurized. Subsequently, it flows into the heat absorber, absorbs ambient heat and is heated, and then returns to the compressor. This conventional refrigeration cycle is shown as a cycle that follows point A → B point → C point → D point on the Mollier diagram of FIG. 4. In the conventional expansion valve, the refrigerant is from point C to point D. Since the pressure is reduced by the isoenthalpy change indicated by the dotted line, the energy of the high-pressure working fluid cannot be used effectively. On the other hand, in a refrigeration cycle that uses an expander instead of an expansion valve, the working fluid that has been decompressed by an equal enthalpy change at the expansion valve in the conventional refrigeration cycle is decompressed by adiabatic expansion from high pressure to low pressure by the expander. However, the isentropic change indicated by the solid line from the C point to the D ′ point is shown, and the energy that can be absorbed by the heat absorber, that is, the energy that can be absorbed from the low heat source side of the refrigeration cycle is expressed as D point → A Since the point can be increased from the point D ′ to the point A, the refrigeration cycle can be made highly efficient.

  For example, as shown in FIG. 8, the expander includes a cylinder 59 having a cylindrical inner space, and an eccentric rotor 61 that performs a revolving motion along the inner circumferential surface of the inner space of the cylinder 59. An expansion chamber 62 is formed between the eccentric rotor 61 and a vane 63 that slides up and down.

  The cylinder 59 includes an opening / closing valve 69, and an inflow port 64 for introducing a high-pressure fluid into the expansion chamber 62 and an outflow port 65 for leading out a low-pressure fluid expanded from the high-pressure fluid to the outside. The vane 63 is pressed by pressing means (not shown), and the lower end portion is always in sliding contact with the outer peripheral surface of the eccentric rotor 61, thereby dividing the expansion side and the discharge side. It is supposed to be. The eccentric rotor 61 is connected to the power recovery shaft 60 via a crankshaft, and the eccentric rotor 61 revolves with respect to the cylinder 59 by the action of high-pressure fluid introduced from the inflow port 64. If it does, the said power collection | recovery shaft 60 will perform a rotational motion via a crankshaft, and this rotational motion is utilized for electric power generation, such as a generator.

  As the eccentric rotor 61 revolves, the expansion chamber 62 formed in the inner space of the cylinder 59 has a portion that was on the suction / expansion side as needed, a portion that was on the discharge side, and a portion that was on the discharge side as needed. The high-pressure fluid suction / expansion action and the discharge action are simultaneously performed in parallel. During the revolving motion of the eccentric rotor 61, the angle range of the suction process in which the high-pressure fluid is supplied into the cylinder 59 and the angle range of the expansion process in which the fluid is expanded are determined in advance. The density ratio of the refrigerant and the discharged refrigerant is set to be constant. The high pressure fluid is introduced into the cylinder in the angular range of the suction process, while the fluid is expanded at a predetermined expansion ratio in the remaining angular range of the expansion process, and the rotational power is recovered. On the other hand, in a vapor compression refrigeration cycle connected to an expander, the high pressure and low pressure of the refrigeration cycle change due to the temperature change of the object to be cooled and the temperature change of the object of heat dissipation. The density of the intake refrigerant and exhaust refrigerant of the expander also varies.

  The expander is designed to obtain the maximum power recovery efficiency when it is operated at the design expansion ratio. FIG. 9A shows the volume change of the expansion chamber under ideal operating conditions. It is a graph which shows the relationship between a pressure change. As shown in FIG. 9A, the high-pressure fluid is supplied into the expansion chamber from the point a to the point b, and starts to expand from the point b. When the point b is passed, the supply of the high-pressure fluid stops, so that the pressure once drops rapidly to the point c, and then gradually decreases to the point d while expanding. Then, after the cylinder volume of the expansion chamber becomes maximum at the point d, the volume is reduced on the discharge side and discharged to the point e. Thereafter, returning to the point a, the inhalation process of the next cycle is started. In the state of this figure, the pressure at the point d coincides with the low pressure of the refrigeration cycle, so that the operation with efficient power recovery is performed.

  When an expander is used in the refrigeration cycle of an air conditioner, the expansion ratio of the refrigeration cycle differs from the design expansion ratio of the expander due to changes in operating conditions such as switching between cooling operation and heating operation and changes in outside air temperature. Cases arise. If the actual expansion ratio of the refrigeration cycle becomes smaller than the design expansion ratio of the expander due to changes in operating conditions, a state occurs in which the pressure in the expansion chamber becomes lower than the low-pressure side pressure of the refrigeration cycle, so-called expansion of the expander An over-expansion phenomenon will occur in the chamber.

  FIG. 9B is a graph showing the relationship between the volume change of the expansion chamber and the pressure change when the overexpansion phenomenon occurs in the expansion chamber, and the low pressure side pressure of the refrigeration cycle is in an increased state. . In this case, after the fluid is supplied into the cylinder between the points a and b, the pressure decreases to the point d according to the design expansion ratio of the expander. On the other hand, the low pressure of the refrigeration cycle is at a point d 'higher than the point d. Therefore, after the expansion process is completed, the refrigerant is pressurized from the point d to the point d 'in the discharge process, and then discharged until the point e', so that the suction process of the next cycle is started.

  In the state shown in FIG. 9B, internal consumption of power is performed in the expander for discharging the refrigerant. That is, at the time of occurrence of overexpansion, the recovery power recovered from the expansion energy of the refrigerant can be obtained only by (area I) − (area II). Compared with the operation state shown in FIG. The recovery power will be greatly reduced. The expander is designed to obtain the maximum power recovery efficiency when the operation is performed at the designed expansion ratio. If an overexpansion phenomenon occurs, the power recovery efficiency will be greatly reduced. There was a problem.

In order to cope with the refrigerant overexpansion phenomenon, for example, as shown in FIG. 8, the outflow port 65 is connected to an intermediate position in the expansion process of the expansion chamber 62, and an opening / closing mechanism 67a and a check valve 68 are provided. A technique is proposed in which a communication passage 67 is provided so that the opening / closing mechanism 67a opens and closes according to the pressure difference between the outflow port 64 and the expansion chamber 62. When overexpansion occurs in the expansion chamber 62 and the pressure in the expansion chamber 62 becomes lower than the pressure in the outflow port 65, the opening / closing mechanism 67 a is opened, and refrigerant is supplied from the outflow port 65 to the expansion chamber 62. The pressure in the expansion chamber 62 is restored to the low pressure of the refrigerant circuit to suppress the overexpansion phenomenon. There is also a method of connecting the inflow port 64 and the expansion chamber 62 through a communication passage 66 having an opening / closing mechanism 66a. (Refer to Patent Document 1 except that the assigned number is different.)
Therefore, in order to reduce the dead volume generated between the check valve 68 and the discharge port of the expansion chamber 62 as much as possible, the check valve 68 is provided near the discharge port of the expansion chamber 62. High-pressure refrigerant from the inflow port 64 flows into the section A indicated by the arrow between the check valve 68 and the discharge port of the expansion chamber 62, and the refrigerant that has flowed in There is a problem that the power recovery efficiency is reduced by that amount because it does not contribute to the power recovery in the chamber 62.
JP 2004-190559 A (page 7, FIG. 4)

  In view of the above-described problems, the present invention can quickly suppress an overexpansion phenomenon caused by a change in the state of a refrigerant circuit in an expansion chamber of an expander that recovers energy, and can also detect dead that exists in the expansion chamber. It is an object of the present invention to provide a refrigerant circuit that reduces space and improves energy recovery efficiency.

  In order to solve the above-described problems, the present invention includes a compressor, a radiator, an expansion chamber and a power recovery shaft in a casing, and expansion that obtains rotational power of the power recovery shaft by a working fluid that flows into the expansion chamber. In the refrigerant circuit in which the compressor and the heat absorber are sequentially connected, an oil separator is provided on the low pressure side of the refrigerant circuit, an oil return path is provided between the oil separator and the expander, and the expansion chamber When the pressure decreases from the low pressure side, the lubricating oil separated by the oil separator is injected into the expansion chamber through the oil return path.

  In addition, an oil separator is provided between the expander and the heat absorber.

  In addition, a compressor, a radiator, an expansion chamber and a power recovery shaft in a casing, an expander that obtains rotational power of the power recovery shaft by working fluid flowing into the expansion chamber, and a heat absorber are sequentially connected. In the refrigerant circuit, an oil reservoir chamber is provided at a lower portion of the expander, and an oil separator having an oil return path communicating with the oil reservoir chamber is provided on the high pressure side of the refrigerant circuit. The lubricating oil separated by the vessel is collected in the oil reservoir chamber.

  The oil separator is provided on the discharge side of the compressor.

  In addition, a flow rate adjusting mechanism is provided in the oil return path.

  According to the present invention, the invention according to claim 1 provides an oil separator on the low pressure side of the refrigerant circuit, an oil return path between the oil separator and the expander, and the pressure in the expansion chamber is When the pressure drops from the low pressure side, the lubricating oil separated by the oil separator is injected into the expansion chamber via the oil return path, thereby reducing the expansion chamber volume and quickly suppressing the occurrence of overexpansion. Can be done.

  In the invention according to claim 2, the oil separator is provided between the expander and the heat absorber, which is on the low pressure side of the refrigerant circuit, so that the pressure of the expansion chamber is located on the low pressure side. When the pressure falls below the pressure in the oil separator, the lubricating oil can be automatically injected into the expansion chamber due to the pressure difference.

  According to a third aspect of the present invention, there is provided an expander having a compressor, a radiator, an expansion chamber and a power recovery shaft in a casing, and obtaining rotational power of the power recovery shaft by a working fluid flowing into the expansion chamber. And a heat absorber connected sequentially to each other, an oil reservoir chamber is provided at a lower portion of the expander, and an oil return path is communicated with the oil reservoir chamber on the high pressure side of the refrigerant circuit. By providing a separator and collecting the lubricating oil separated by the oil separator in the oil reservoir chamber, when overexpansion occurs in the expansion chamber, the lubricating oil is quickly injected into the expansion chamber from the oil reservoir chamber. On the other hand, the amount of lubricating oil can be kept constant by recovering the lubricating oil from the oil separator to the oil reservoir.

  According to a fourth aspect of the present invention, the oil separator is provided on the discharge side of the compressor, so that the lubricating oil separated by the oil separator can be quickly put into the oil sump chamber of the expander at high pressure. It can be collected.

  Further, the invention according to claim 5 can appropriately control the amount of lubricating oil recovered from the oil separator to the oil sump chamber of the expander by a configuration in which a flow rate adjusting mechanism is provided in the oil return path. It has become.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings.

  FIG. 1 is a refrigerant circuit in a first embodiment according to the present invention, and FIG. 2 is a cross-sectional view showing an expander provided in the refrigerant circuit. FIG. 3 is a cross-sectional view showing the expansion process of the refrigerant, and FIG. 4 is a Mollier diagram. FIG. 5 is a cross-sectional view showing a compression / expansion mechanism in which the compression mechanism and the expansion mechanism are integrated. FIG. 6 is a cross-sectional view showing a refrigerant circuit in the second embodiment and an expander provided in the refrigerant circuit, and FIG. 7 is a cross-sectional view of the expander showing another embodiment in the second embodiment. It is.

  As shown in FIG. 1A, the refrigerant circuit 1 according to the present invention sequentially connects a compressor 2, a radiator 3, an expander 4, an oil separator 5, and a heat absorber 6, and A first oil return path 7 connecting the oil separator 5 and the expander 4 and a second oil return path 8 connecting the oil separator 5 and the suction side of the compressor 2 are configured. In the refrigerant circuit 1, for example, a carbon dioxide refrigerant as a natural refrigerant that undergoes a phase change at a critical pressure or higher circulates. The compressor 2 is composed of a scroll compressor or a rotary compressor, and the radiator 3 and the heat absorber 6 are arranged in parallel with a large number of fins arranged in parallel and the fins. It is composed of a so-called cross fin type fin-and-tube heat exchanger composed of a meandering tube.

  The carbon dioxide refrigerant that has been compressed by the compressor 2 and has become high temperature and high pressure flows into the radiator 3 and releases the heat by the radiator 3 to be cooled. The refrigerant cooled by releasing heat flows into the expander 4 and expands in the expander 4 to a low temperature and low pressure. The low-temperature and low-pressure refrigerant flows into the heat absorber 6 through the oil separator 5, absorbs heat by the heat absorber 6, is heated, and then returns to the compressor 2. The refrigerant expanded in the expander 4 is configured to rotationally drive a power recovery shaft 12 (described later) provided in the expander 4 by the expanding energy.

  The oil separator 5 separates the inflowing gaseous refrigerant from the lubricating oil contained in the gaseous refrigerant in the form of particles. The separated lubricating oil is recirculated to the expander 4 through the first oil return path 7 and recirculated to the compressor 2 through the second oil return path 8.

  In addition, you may provide the oil separator 86 in the refrigerant circuit 80 shown in FIG.1 (B). The refrigerant circuit 80 includes an expander-integrated compressor 81, a first four-way valve 84, a radiator 82, a second four-way valve 85, and a heat absorber 83, which will be described later, to sequentially connect the refrigerant circuit. In addition, an oil separator 86 is provided between the expander-integrated compressor 81 and the second four-way valve 85. The oil separator 86 includes a first oil return path 87 for returning the lubricating oil to the expansion mechanism portion of the expander-integrated compressor 81 and a second oil return path 88 for returning the oil to the compression mechanism portion. Is provided.

  In the refrigerant circuit 80, by switching the first four-way valve 84 and the second four-way valve 85, it is possible to perform a cooling operation and a heating operation. The refrigerant flows in the direction indicated by, and in the heating operation, the refrigerant flows in the direction indicated by the broken line. The function of the oil separator 86 is the same as that of the oil separator 4 described in the refrigerant circuit 1.

  The expander 4 in the first embodiment of the present application is formed in a cylindrical shape with the upper and lower surfaces closed as shown in the cross-sectional view from above in FIG. 2A and the side cross-sectional view in FIG. Casing 9, an annular cylinder 10 having an upper wall, a lower wall, and a side wall formed in the upper portion of the casing 9, and an eccentric rotor provided in an internal space of the cylinder 10 so as to be capable of revolving. 11 and a power recovery shaft 12 connected to the eccentric rotor 11 and pivotally supported by the casing 9.

  The eccentric rotor 11 is fitted to the outer peripheral edge of a crankshaft 11b formed on the power recovery shaft 12, and is eccentrically connected to the power recovery shaft 12 so that one end of the outer peripheral surface is connected to the inside of the cylinder 10. The inner space of the cylinder 10 revolves while sliding on the wall surface.

  The casing 9 is formed with a vane storage portion 16 protruding outward. In the vane storage portion 16, a vane 17 that is supported so as to be able to advance and retreat in a forward / backward direction, a front end of which is in contact with the outer peripheral surface of the eccentric rotor 11, and a sliding contact, a rear portion of the vane 17, A spring 18 is provided as a pressing means that is provided between the inner wall 16 and presses the vane 17 against the outer peripheral surface of the eccentric rotor 11. Further, an inflow port 14 provided with an on-off valve 14a for introducing a high-pressure refrigerant and an outflow port 15 for allowing the low-pressure refrigerant to flow out are projected from the casing 9, and these inflow ports 14 and outflow The port 15 is disposed so as to face the vane 17.

  An expansion chamber 13 is formed in a space surrounded by one side of the vane 17, the outer peripheral surface of the eccentric rotor 11, and the inner wall surface of the cylinder 10. The high-pressure refrigerant flowing into the chamber 13 revolves the eccentric rotor 11 counterclockwise with the high pressure, rotates the power recovery shaft 12 connected thereto, and the volume of the expansion chamber 13 increases. As it increases, the volume expands and becomes a low-pressure refrigerant. The refrigerant that has been expanded to a low pressure flows out from the outflow port 15.

  The power recovery shaft 12 connected to the eccentric rotor 11 is connected, for example, to a generator or the like at an upper portion thereof, and the eccentric rotor 11 expands high-pressure refrigerant flowing into the cylinder 10. When the power recovery shaft 12 is driven to revolve by energy, and the power recovery shaft 12 is driven to rotate, a generator or the like connected to the shaft performs a power generation operation, and thereby, the expansion energy of the refrigerant is wasted. It can be used effectively without any problems.

  The power recovery shaft 12 is provided with an oil passage 12a having a check valve 12b along the central axis, and the eccentric rotor 11 has the oil passage 12a, the expansion chamber 13, and the like. An oil injection hole 11a is formed in the horizontal direction for communicating the. In addition, the lower part of the casing 9 is folded in an L shape with one end rotatably connected to the oil passage 12a of the power recovery shaft 12 and the other end connected to the first oil return passage 7. A bent oil introduction pipe 19 is provided.

  Next, operations of the refrigerant circuit 1 and the expander 4 will be described. In the expander 4, as described above, the high-temperature and high-pressure refrigerant that has flowed into the internal space of the cylinder 10 from the inflow port 14 expands in the expansion chamber 13 and rotates the power recovery shaft 12. The refrigerant becomes a low-temperature and low-pressure refrigerant and flows out from the outflow port 15.

  The on-off valve 14 a provided in the inflow port 14 opens and closes along with the revolving motion of the eccentric rotor 11. For example, in the vicinity of the power recovery shaft 12, the power recovery shaft 10 An angle sensor (not shown) that detects the rotation angle is provided, and the opening / closing operation of the on-off valve 14a is performed based on the detected rotation angle. Further, a cam may be attached to the power recovery shaft 12, and the opening / closing operation of the opening / closing valve 14a may be performed in accordance with the operation of the cam.

  During the revolving motion of the eccentric rotor 11, an angle range of a suction process in which high-pressure refrigerant is supplied into the cylinder 10 by an opening / closing operation of the on-off valve 14a and an angle range of an expansion process in which fluid is expanded are predetermined. It has been. FIG. 3A shows a process in which the on-off valve 14a is opened and a high-pressure refrigerant flows into the expansion chamber 13, and the eccentric rotor 11 rotates in the direction indicated by the arrow from the state of FIG. The on-off valve 14a is closed, and the supply of the refrigerant to the expansion chamber 13 is stopped.

  FIG. 3B shows a state in which the high-pressure refrigerant that has flowed into the expansion chamber 13 expands and increases the volume of the expansion chamber 13 to rotate the eccentric rotor 11. The refrigerant expands. As a result, the pressure gradually decreases and the refrigerant moves to a low-pressure refrigerant.

  FIG. 3C shows a state in which the refrigerant expands and the volume of the expansion chamber 13 is maximized. The refrigerant that has dropped to a predetermined pressure due to expansion flows out of the discharge port 15. It has come to go. At this time, the on-off valve 14a is opened, and high-pressure refrigerant is again introduced into the cylinder 10 from the inflow port 14.

  In the compressor 2, a lubricating oil reservoir is provided to lubricate the internal mechanism, and when the refrigerant is compressed, a phenomenon occurs in which the lubricating oil in the lubricating oil reservoir is mixed with the refrigerant. The carbon dioxide refrigerant compressed by the compressor 2 becomes high temperature and pressure and mixed with lubricating oil flows into the radiator 3 and releases heat to be cooled. The refrigerant cooled by releasing heat flows into the expander 4, expands in the expander 4, and rotates the power recovery shaft 12 by expansion energy to become a low temperature and low pressure, and the oil separator 5 flows into. In the oil separator 5, the refrigerant and the lubricating oil mixed therewith are separated. The refrigerant separated from the lubricating oil subsequently absorbs heat by the heat absorber 6 and then returns to the compressor 2.

  When an overexpansion phenomenon occurs in the expansion chamber 13 of the expander 4 and the pressure in the expansion chamber 13 is lower than the pressure in the oil separator 5 located on the low pressure side in the refrigerant circuit 1, the oil separation The lubricating oil separated in the container 5 is sent to the expander 4 through the first oil return path 7 because the pressure in the oil separator 5 is higher than that of the expansion chamber 13. Yes. As shown in FIG. 2, the lubricating oil sent to the first oil return passage 7 passes through the oil introduction pipe 19 and is sucked into the oil passage 12a of the rotating power recovery shaft 12, so that the oil passage The inside of 12a rises. Subsequently, the lubricating oil is injected into the expansion chamber 13 from the oil injection hole 11a. Thereby, by reducing the volume of the expansion chamber 13 and increasing the pressure in the expansion chamber 13, it is possible to suppress the phenomenon of overexpansion, while reducing the volume of the dead space from the expansion chamber 13. Thus, an efficient power recovery operation can be performed. A part of the lubricating oil separated by the oil separator 5 is collected in the lubricating oil reservoir of the compressor 2 through the second oil return path 8.

  In the expander 4 described above, when the power recovery shaft 10 is rotationally driven, a generator or the like connected to the power recovery shaft 10 performs a power generation operation, and thereby, the expansion energy of the refrigerant is not wasted. Although it can be used effectively, as shown in FIG. 4, the expansion mechanism and the compression mechanism of the compressor can be integrated to effectively use the expansion energy.

  An expander-integrated compressor 100 shown in FIG. 5 houses a compression mechanism section 102, an electric motor section 103, and an expansion mechanism section 104 inside a casing 101. The compression mechanism 102 constitutes a scroll compressor including a fixed scroll 114, a turning scroll 115, and frames 112 and 113, and is provided with a suction port 116 and a discharge port 117. The electric motor unit 103 includes a stator 108, a rotor 109, and a main shaft 105, and the main shaft 105 is connected to the expansion mechanism unit 104.

  The expansion mechanism 104 includes a cylinder 106 and an eccentric rotor 107 that revolves within the cylinder 106, and is provided with an inflow port 11 and an outflow port 110. When the eccentric rotor 107 is rotationally driven by the refrigerant flowing from the inflow port 11, the rotational force of the main shaft 105 connected thereto is urged.

  Thus, the expander-integrated compressor is configured by integrating the compressor and the expander, and the rotational driving force of the expansion mechanism unit 104 drives the compression mechanism unit 102 together with the electric motor unit 103. ing. This can reduce the energy of the motor unit 103 that drives the compression mechanism unit 102 by the amount of power recovered in the process of adiabatic expansion C point → D ′ point shown in the Mollier diagram of FIG. Thus, the energy recovery efficiency can be improved.

  Next, a second embodiment will be described. As shown in FIG. 6A, the refrigerant circuit 20 in the second embodiment sequentially connects a compressor 21, an oil separator 22, a radiator 23, an expander 24, and a heat absorber 25. In addition, the second oil connecting the oil separator 22 and the expander 24 and connecting the first oil return path 26 provided with a flow rate adjusting mechanism 28 and the oil separator 22 and the suction side of the compressor 21. And a return path 27.

  As shown in the side sectional view of FIG. 6B, the expander 24 in the second embodiment is formed in a casing 29 formed in a cylindrical shape with the upper surface and the lower surface closed, and an upper portion in the casing 29. The expansion mechanism portion 30 is formed, an oil reservoir chamber 31 formed below, and a power recovery shaft 35 pivotally supported at the central portion of the casing 29.

  The expansion mechanism section 30 has an upper wall, a lower wall, and a side wall, a cylinder 32 having a cylindrical inner space, and a ring-shaped eccentric rotor fitted to the outer periphery of the crankshaft of the power recovery shaft 35. 33. The eccentric rotor 33 revolves in the internal space of the cylinder 32 while sliding one end of the outer peripheral surface thereof to the inner wall surface of the cylinder 32, whereby an expansion chamber 34 is formed. .

  Lubricating oil is stored in an oil reservoir chamber 31 formed in the lower portion of the casing 29, and the power recovery shaft 35 is directed downward so that a lower end portion is immersed in the oil in the oil reservoir chamber 31. While extending, an oil passage 35a provided with a check valve 35b is formed in the shaft core. The eccentric rotor 33 is formed with an oil injection hole 33a that allows the oil passage 35a and the internal space of the cylinder 32 to communicate with each other. When the power recovery shaft 35 starts to rotate, the oil stored in the oil reservoir chamber 31 is sucked into the oil passage 35a by the rotational force and supplied to the sliding portion such as the eccentric rotor 33. ing. An oil introduction pipe 36 connected to the first oil return path 26 is provided at the lower part of the casing 29.

  Next, the operation will be described. The carbon dioxide refrigerant compressed by the compressor 21 to high temperature and pressure flows into the oil separator 22 and is separated into refrigerant and lubricating oil. The high-temperature and high-pressure refrigerant flows into the radiator 23, releases heat, and is cooled. The cooled refrigerant flows into the expander 24, expands in the expander 24, and expands in the expander 24. The recovery shaft 35 is driven to rotate to a low temperature and low pressure, and after the surrounding heat is absorbed by the heat absorber 25, it is returned to the compressor 21.

  The lubricating oil separated by the oil separator 22 is sent to the oil reservoir chamber 31 of the expander 24 through the first oil return path 26 and stored therein. At this time, the flow rate adjusting mechanism 28 appropriately adjusts the amount of lubricating oil delivered. The lubricating oil stored in the oil reservoir chamber 31 is sucked into the oil passage 35a of the rotating power recovery shaft 35 and rises. Subsequently, the lubricating oil is injected into the expansion chamber 34 from the oil injection hole 33a, thereby suppressing the occurrence of overexpansion in the expansion chamber 34, while reducing the volume of the dead space. By reducing from the expansion chamber 34, an efficient power recovery operation can be performed. Further, by supplying lubricating oil from the oil separator 22, the oil reservoir chamber 31 can always maintain an appropriate amount of lubricating oil without causing a shortage of lubricating oil. A part of the lubricating oil separated by the oil separator 22 is collected in the lubricating oil reservoir of the compressor 21 through the second oil return path 27.

  Next, another embodiment of the second embodiment will be described. As shown in FIG. 7, the expander 37 is provided with a pressure sensor 44 in an expansion chamber 40 formed by a cylinder 38, an eccentric rotor 39, and a vane 43. In addition, a pressure sensor 46 is provided at the outflow port 42 facing the inflow port 41, and the pressure sensor 44 and the pressure sensor 46 are connected to a control unit (not shown) by a lead wire 47.

  Since the oil separator 27 is disposed on the high pressure side in the refrigerant circuit 20, pressure is applied to the lubricating oil separated by the oil separator 22, and the oil separator 27 is constantly connected via the first oil return path 26. Lubricating oil tends to flow through the expander 24. When a so-called over-expansion phenomenon occurs in which the detection value of the pressure sensor 44 disposed in the expansion chamber 40 is lower than the detection value of the pressure sensor 46 disposed in the outflow port 42, the inflow adjusting mechanism 28 is It is opened according to the pressure difference, and an appropriate amount of lubricating oil is sent to the expander 24.

It is a refrigerant circuit in the 1st example by the present invention. (A) is sectional drawing from the top which shows the expander with which the same refrigerant circuit was equipped. (B) is side sectional drawing. It is sectional drawing which shows the expansion process of the refrigerant | coolant in an expander. It is a Mollier diagram which shows the refrigerating cycle in an expander. It is sectional drawing which shows the compression-expansion unit with which the compression mechanism and the expansion mechanism were united. (A) is a refrigerant circuit in the second embodiment.

(B) is a sectional side view showing an expander provided in the refrigerant circuit.
It is sectional drawing of the expander which shows the other Example in a 2nd Example. It is sectional drawing which shows an example of the conventional expander. (A) And (B) is explanatory drawing which shows the change of the pressure and volume in an expansion chamber.

Explanation of symbols

Reference Signs List 1 refrigerant circuit 2 compressor 3 radiator 4 expander 5 oil separator 6 heat absorber 7 first oil return path 8 second oil return path 9 casing 10 cylinder 11 eccentric rotor 11a oil injection hole 12 power recovery shaft 12a oil path 13 Expansion chamber 14 Inflow port 14a On-off valve 15 Outflow port 16 Vane storage portion 17 Vane 18 Spring 19 Oil introduction pipe 20 Refrigerant circuit 21 Compressor 22 Oil separator 23 Radiator 24 Expander 25 Heat absorber 26 First oil return path 27 Two oil return path 28 Flow rate adjusting mechanism 29 Casing 30 Expansion mechanism 31 Oil reservoir chamber 32 Cylinder 33 Eccentric rotor 34 Expansion chamber 35 Power recovery shaft 35a Oil passage 36 Oil introduction pipe

Claims (5)

A refrigerant comprising a compressor, a radiator, an expansion chamber and a power recovery shaft in a casing, an expander for obtaining rotational power of the power recovery shaft by a working fluid flowing into the expansion chamber, and a heat absorber In the circuit
An oil separator is provided on the low pressure side of the refrigerant circuit, and an oil return path is provided between the oil separator and the expander. When the pressure in the expansion chamber decreases from the low pressure side, the oil separator A refrigerant circuit provided with an expander, wherein the lubricating oil separated in step (b) is injected into the expansion chamber through the oil return path.   The refrigerant circuit provided with the expander according to claim 1, wherein the oil separator is provided between the expander and the heat absorber. A refrigerant comprising a compressor, a radiator, an expansion chamber and a power recovery shaft in a casing, an expander for obtaining rotational power of the power recovery shaft by a working fluid flowing into the expansion chamber, and a heat absorber In the circuit
An oil reservoir chamber is provided at the lower portion of the expander, and an oil separator having an oil return path communicating with the oil reservoir chamber is provided on the high-pressure side of the refrigerant circuit, and lubrication separated by the oil separator is provided. A refrigerant circuit comprising an expander, wherein oil is collected in the oil reservoir.   The refrigerant circuit having an expander according to claim 3, wherein the oil separator is provided on a discharge side of the compressor.   The refrigerant circuit provided with the expander according to claim 3 or 4, wherein a flow rate adjusting mechanism is provided in the oil return path.

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