JP2009270529A - Positive displacement fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive displacement fluid machine improving energy efficiency of refrigeration cycle by reducing mechanical loss and internal leak of an expander and an auxiliary compressor with a simple structure having good assemblability. <P>SOLUTION: This positive displacement fluid machine is provided with a lubricating oil supply mechanism keeping communication between a turning scroll back surface space of a scroll expander and a roller inner space of a rotary auxiliary compressor and making lubricating oil flow to a back pressure space from an oil supply passage of a crankshaft through a bearing part, and a back pressure adjusting mechanism adjusting back pressure to a prescribed pressure between the back pressure space and a suction space of the rotary auxiliary compressor. A seal member is installed at a roller end surface part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a positive displacement fluid machine, and more particularly, to a positive displacement fluid machine including a scroll expander that recovers fluid energy in an expansion process in order to improve a coefficient of performance (COP) that is energy efficiency of a refrigeration cycle apparatus. Is.

Conventionally, as a positive displacement fluid machine equipped with a scroll expander, there is one disclosed in Japanese Patent Application Laid-Open No. 2007-332819 (Patent Document 1). In this positive displacement fluid machine, an expander unit and a compressor unit are housed in a single sealed container, the working fluid flowing into the expander unit is expanded to move the expander, and the driving force causes the crankshaft to pass through the crankshaft. To operate the compressor section.

  Here, each of the expander units is composed of a fixed scroll and a orbiting scroll, each of which has a spiral wrap formed upright on an end plate, and meshes with each other to form a plurality of working chambers, and opens at the center of the fixed scroll. This is a scroll expander including a fluid inlet, a fluid outlet opening at the outer periphery of the fixed scroll, and a first eccentric shaft connected to the orbiting scroll. The compressor section includes a cylinder, an end plate that closes the opening at both ends of the cylinder, a cylindrical roller that rotates eccentrically inside the cylinder, and a cylinder, a roller, and an end plate that are in contact with the outer peripheral surface of the roller. The rotary compressor includes a vane portion that partitions the space to be formed, a spring that urges the vane portion to press it against the roller, and a second eccentric shaft portion that is coupled to the roller.

  Here, in the working chamber communicating with the inlet of the expander unit, the radial force due to the refrigerant works most effectively when the volume is maximum. On the other hand, the compressor section has a lower pressure in the working chamber on the discharge chamber side than the working chamber on the discharge port side partitioned by vanes in the cylinder at startup, and the working chamber on the suction port side has the maximum volume due to the pressure difference. A rotational torque is generated that moves the roller to the position. As a result, the rotation position of the orbiting scroll is set so that the volume of the working chamber communicating with the inlet of the expander section is maximized when the vane of the compressor section protrudes most into the cylinder (bottom dead center). As a result, it is possible to obtain the maximum starting torque generated from the expander unit and the compressor unit at the time of startup, so that it is possible to realize a stable startup of the positive displacement fluid machine without using an auxiliary motor. It has become.

JP 2007-332819 A

  In the positive displacement fluid machine of Patent Document 1 described above, since it is not necessary to particularly provide a starting means such as an auxiliary motor, it can contribute to the cost reduction of the device, but there is room for improvement as follows. .

  In positive displacement fluid machines, the internal leakage of working fluid that occurs in the gaps between the members that make up the working chamber and the mechanical friction loss at the sliding parts of each member greatly affect the efficiency of the positive displacement fluid machine. No mention is made of the lubrication of the sliding part, which is indispensable for reducing the friction loss. Further, from FIG. 1 of Patent Document 1, two positive displacement machines, an expander unit 1 and a compressor unit 3 are connected by a single crankshaft 21, and the crankshaft 21 has an expander eccentric shaft 21 a and a compression unit. Since there are two eccentric parts of the machine eccentric shaft 21b and protrudes outside the shaft outer diameter of the frame 11 part, it is difficult to assemble the frame 11 in the illustrated state. Although the frame 11 can be assembled if it is a half-divided structure, there is a problem of an increase in cost. Further, the rotational balance of the crankshaft 21 on which two eccentric masses act is not particularly taken into consideration.

  Further, since there is a difference between the back surface of the orbiting scroll 7 of the expander unit 1 and the internal pressure of the compressor unit 3, a certain axial force is applied to the crankshaft 21, and mechanical wear loss occurs in the crankshaft 21 and its bearings. This greatly affects the efficiency of positive displacement fluid machinery.

  Thus, in the positive displacement fluid machine of Patent Document 1, the lubrication / sealability of each sliding part in the expander part 1 and the compressor part 3 and the mechanical wear loss in the crankshaft 21 and its bearings are taken into consideration. In addition, there is a problem that it is difficult to assemble, and there remains a problem in putting the positive displacement fluid machine into practical use. For this reason, it has not been possible to realize a small-sized, low-cost, high-efficiency positive displacement fluid machine.

  An object of the present invention is to provide a positive displacement fluid machine that is easy to assemble, reduces internal leakage and mechanical friction loss of an expander and a sub compressor, and improves energy efficiency of a refrigeration cycle apparatus. It is in.

  Another object of the present invention is to improve the reliability and energy efficiency of the refrigeration cycle by maintaining a good lubrication and sealing performance of the sliding parts of the expander and sub-compressor with a structure that is easy to assemble. Another object of the present invention is to provide a positive displacement fluid machine.

  In order to achieve the above-mentioned object, the present invention arranges a scroll expander and a rotary subcompressor in a closed container in a laminated form, and connects both via a crankshaft having two eccentric parts, In the positive displacement fluid machine that expands the fluid with the expander and drives the sub-compressor, the scroll expander includes an expansion portion that meshes a fixed scroll and a orbiting scroll to form a working chamber; and A fixed scroll, and a frame for sandwiching the orbiting scroll between the fixed scroll and one of the eccentric portions of the crankshaft is rotatably fitted to an orbiting bearing located at the center of the orbiting scroll. The rotary sub-compressor comprises a roller rotatably fitted to the other eccentric portion of the crankshaft, and a reciprocating motion with the tip in contact with the roller. And a vane that partitions the inside of the cylinder into a suction chamber and a compression chamber, and an end plate that pivotally supports the crankshaft and closes both end openings of the cylinder, and the crankshaft constitutes the scroll expander An oil supply path for supplying lubricating oil to the back space of the orbiting scroll is provided, and the pressure in the back space of the orbiting scroll and the inner space of the rollers constituting the rotary sub-compressor is set to high pressure (discharge pressure) and low pressure (suction pressure). It is characterized by being maintained at an intermediate pressure.

  In order to achieve the above-mentioned another object, the present invention arranges a scroll-type expander and a rotary sub-compressor in a closed container in a stacked manner, and both are disposed via a crankshaft having two eccentric portions. In the positive displacement fluid machine in which the fluid is expanded by the expander and the sub-compressor is driven, the scroll expander is an expansion that meshes the fixed scroll and the orbiting scroll to form a working chamber. And a frame for fixing the fixed scroll and sandwiching the orbiting scroll between the fixed scroll and one eccentric portion of the crankshaft rotating on the orbiting bearing located at the center of the orbiting scroll The rotary sub-compressor is configured to be freely fitted, and a roller that is rotatably fitted to the other eccentric portion of the crankshaft and a tip of the roller are in contact with each other. The scroll expander includes a vane that reciprocates and partitions the inside of the cylinder into a suction chamber and a compression chamber, and an end plate that pivotally supports the crankshaft and closes both end openings of the cylinder. An oil supply path for supplying lubricating oil to the back space of the orbiting scroll, and the back space of the orbiting scroll and the inner space of the roller constituting the rotary subcompressor communicate with each other, and the orbiting bearing from the oil supply passage of the crankshaft. A lubricating oil supply mechanism that allows lubricating oil to flow into the back space through the section, and a back pressure adjustment mechanism that sets the back space to a predetermined pressure between the back space and the suction space of the rotary sub compressor It is characterized by.

  Further, a seal member is disposed on an end surface portion of a roller constituting the rotary subcompressor. The slewing bearing and the lower bearing located at both ends of the crankshaft are slide bearings, and the diameters of both bearings are substantially the same. Further, the main bearing of the crankshaft and the roller inner bearing are rolling bearings. The fluid may be connected to a refrigeration cycle using carbon dioxide as a refrigerant.

  According to the present invention, the pressure in the back space of the orbiting scroll constituting the scroll expander and the inner space of the roller constituting the rotary subcompressor is set to a pressure intermediate between the high pressure (discharge pressure) and the low pressure (suction pressure). By holding, the axial force acting on the orbiting scroll of the expander is canceled out with a simple structure, so that mechanical friction loss is reduced and the expander efficiency can be improved. Thus, it is possible to improve the compressor efficiency by reducing the pressure difference, and to improve the energy efficiency of the refrigeration cycle apparatus.

  Further, according to the present invention, the back space of the orbiting scroll constituting the scroll expander and the roller inner space constituting the rotary subcompressor communicate with each other, and the space from the oil supply passage of the crankshaft to the space via the bearing portion. By providing a lubricating oil supply mechanism for injecting lubricating oil and a back pressure adjusting mechanism for adjusting the pressure of the space to a predetermined pressure between this space and the suction space of the rotary sub-compressor, the structure is simple. The lubrication of the sliding parts of the expander and the sub-compressor can be satisfactorily maintained to ensure high reliability, and the energy efficiency of the refrigeration cycle apparatus can be improved.

  Hereinafter, 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 provided with a positive displacement fluid machine 4 according to Embodiment 1 of the present invention. 2 is a longitudinal sectional view of the positive displacement fluid machine, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a sectional view taken along line BB in FIG. 1 to 4, the positive displacement fluid machine 4 includes an expander 4b that converts the expansion energy of the working fluid in the refrigeration cycle into mechanical energy, and a sub-compressor 4c that performs work by the converted mechanical energy. The expander 4b and the sub-compressor 4c are stacked in the hermetic container 4a, and are housed by being connected to each other via a single crankshaft 4d.

  The refrigeration cycle apparatus 1 according to the first embodiment of the present invention includes an expander 4b between the radiator 3 and the evaporator 5, and 2 denotes a main compressor of the refrigeration cycle apparatus 1 (symbol MC stored in the sealed container 2a). (2) is a suction pipe, 2e is a discharge pipe, and 3 is a radiator, and 6 is an expansion that bypasses the expander 4b. It is a valve.

  Taking the cooling operation as an example, the flow of the refrigerant that is the working fluid will be described. The high-temperature and high-pressure refrigerant discharged from the discharge pipe 2d of the main compressor 2 enters the radiator 3 and is cooled to lower the temperature. The refrigerant discharged from the radiator 3 enters the expander 4b through the expander inflow pipe 8 disposed in the upper part of the closed container 4a of the positive displacement fluid machine 4, where the expansion operation is performed to convert the expansion energy into mechanical energy. The crankshaft 4d is driven after conversion, and discharged from the expander outflow pipe 9 as a low-temperature, low-pressure gas-liquid two-phase refrigerant. The refrigerant exiting the expander 4b enters the evaporator 5 to absorb heat and gas, and is sucked into the sub compressor 4c of the positive displacement fluid machine 4 through the sub compressor suction pipe 13. The refrigerant pressurized in the sub-compressor 4c is discharged from the sub-compressor discharge pipe 14, returns to the main compressor 2 through the suction pipe 2d of the main compressor 2, and is compressed again to be a high-temperature / high-pressure gas refrigerant. Then, the discharge pipe 2e flows out to the external cycle again.

  The main compressor 2 is a so-called high-pressure chamber type compressor in which the inside of the sealed container 2a has a discharge pressure atmosphere, and the refrigerant compressed by the main compression mechanism 2b is discharged into the sealed container 2a, where oil and gas Are separated. Lubricating oil 7 is stored in the sealed container 4a of the positive displacement fluid machine 4 and the sealed container 2a of the main compressor 2, and the oil level of both is kept constant by the oil equalizing pipe 10 and the pressure equalizing pipe 11. ing. The above cycle is repeated and the cooling action by the evaporator 5 is continued. By providing the positive displacement fluid machine 4 of the present embodiment, the expansion process becomes isentropic change, the refrigeration effect is increased and the refrigerating capacity is increased, and the fluid energy in the expansion process is converted into mechanical energy by the expander 4b. Since part of effective compression work is shared by driving the compressor 4c, the gas compression work of the main compressor 2 can be reduced and the COP of the refrigeration cycle apparatus 1 can be improved.

  Next, the structure and operation of the scroll expander and the rolling piston type rotary subcompressor of the positive displacement fluid machine 4 will be described. An expander 4b is disposed in the upper part of the sealed container 4a. The expander 4b is a scroll type expander including an expansion mechanism unit 22 having the fixed scroll 20 and the orbiting scroll 21 as main components. The expansion mechanism part 22, the upper frame 23, the Oldham ring 24, and the crankshaft 25 are the main components. The fixed scroll 20 includes a spiral fixed scroll wrap 20a and a fixed scroll end plate 20b on which the fixed scroll wrap 20a stands upright. An inflow port 20c is formed at the center of the fixed scroll end plate 20b. A space between the upper part of the fixed scroll 20 and the sealed container 4a is a temporary storage space for the high-pressure working fluid flowing in from the expander inflow pipe 8 so as to reduce fluctuations in the expander inflow pressure.

  The orbiting scroll 21 includes a spiral orbiting scroll wrap 21a and an orbiting scroll end plate 21b on which the orbiting scroll wrap 21a stands upright. An orbiting bearing 21c is provided at the center of the orbiting scroll end plate 21b on the side opposite to the orbiting scroll wrap. The orbiting scroll 21 transmits power to the eccentric portion 25a located at the upper end of the crankshaft 25 via the orbiting bearing 21c to rotate the shaft. The expansion mechanism 22 has a working chamber formed by engaging the fixed scroll 20 and the orbiting scroll 21 with each other. The fixed scroll 20 is fixed to the upper frame 23 by fastening bolts 26, and the orbiting scroll 21 is sandwiched between the fixed scroll 20 and the upper frame 23 so as to be capable of orbiting. The Oldham ring 24 is provided between the orbiting scroll 21 and the upper frame 23 so as to prevent the orbiting scroll 21 from rotating.

  On the other hand, in the sub compressor 4 c, both end openings of the cylinder 30 are closed by a lower frame (end plate) 28 that also serves as a shaft support for the crankshaft 25 and a lower bearing (end plate) 29. A cylindrical inner peripheral surface 31 a (eccentric bearing, roller inner bearing) is formed at the center of the cylinder 30. The crankshaft 25 is formed with another eccentric portion 25b at a portion corresponding to the cylindrical inner peripheral surface 31a of the roller 31 (the crankshaft eccentric portion 25a on the expander 4b side and the crankshaft eccentricity on the sub compressor 4c side). The rotational phase of the portion 25b is the same phase), and is rotatably fitted in the eccentric portion bearing 31a mounted on the inner peripheral surface of the cylindrical roller 31.

  A plate-like vane 32 is pressed by a vane spring 32a on the cylindrical outer peripheral surface of the roller 31, and seal rings 41 are mounted on both upper and lower end surfaces. On the outside of the cylindrical inner peripheral surface 30a of the cylinder 30, a vane groove 30b in which the vane 32 can reciprocate and a spring hole 30d into which the vane spring 32a is inserted are formed. A plug 32b fitted with a vane spring 32a is press-fitted and fixed to the open end of the spring hole 30d, thereby forming a back space of the vane 32.

  The sub compressor suction pipe 13 attached to the sealed container 4a is connected to the suction passage 30e of the cylinder 30, and the refrigerant gas sucked from the sub compressor suction pipe 13 passes through the suction passage 30e to the cylinder 30. The roller 31 moves by eccentric rotation along the cylindrical inner peripheral surface 30a of the cylinder 30 by the rotation of the crankshaft 25, passes through the discharge passage 30f from the sub compressor discharge pipe 14 to the outside. Outflow to refrigeration cycle.

  The back space of the vane 32 and the discharge passage 30f are communicated with each other through a communication hole 30g, and the pressure in the back space of the vane 32 is maintained at the discharge pressure of the sub compressor 4c. Due to the internal pressure and the spring force of the vane spring 32a, the vane 32 is always pressed against the outer peripheral surface of the roller 31 with an appropriate force to seal the contact portion. A balance weight 35 is attached to the lower part of the eccentric part 25a located at the upper end of the crankshaft 25 to balance the rotating shaft system. The periphery of the balance weight 35 is surrounded by the outer periphery of the lower frame 28 having a main bearing 28a at the center, and the space on the back side of the orbiting scroll 21 formed by the upper frame 23 of the expander 4b and the lower frame 28 is A pressure compartment is provided as the back pressure chamber 27.

  Further, since the main bearing 28a of the lower frame 28 and the eccentric part bearing 31a of the roller 31 are both constituted by rolling bearings formed of cylindrical bearings, the back pressure chamber 27 and The inner space of the roller 31 communicates with the same intermediate pressure. This intermediate pressure is an intermediate pressure between a high pressure (discharge pressure) and a low pressure (suction pressure). The lower frame 28 and the lower bearing 29 are fastened and fixed by fastening bolts 33 with the cylinder 30 interposed therebetween, and 34 is a set bolt for positioning the cylinder.

  The expander 4b and sub-compressor 4c having the above-described configuration are expanded when the upper frame 23 and the lower frame 28 are fixed by assembly bolts (not shown) in a state of being stacked in the closed container 4a. The outer periphery of the upper frame 23 of the machine 4b is fitted and fixed to the inner periphery of the sealed container 4a. Lubricating oil 7 is stored at the bottom of the airtight container 4a. An oil supply piece 25d is attached to the lower end of the crankshaft 25 of the sub-compressor 4c, and the shaft rotates through an oil supply passage 25c formed in the crankshaft 25. Lubricating oil is pulled up by the centrifugal pump action, and both the orbiting bearing 21c and the lower bearing 29 of the orbiting scroll 21 are constituted by sliding bearings, and the pressure in the sealed container 4a and the back pressure chamber 27 are passed through the bearing gap with the crankshaft 25. Thus, a lubricating oil supply path (lubricating oil supply mechanism) for allowing the lubricating oil 7 to flow into the back pressure chamber 27 stably and constantly is formed.

  Here, the two plain bearings 21 c of the orbiting scroll 21 and the lower bearing 29 located at both ends of the crankshaft 25 have substantially the same diameter of the crankshaft 25, and the space between both bearings is an intermediate pressure. (Back pressure) is kept constant, so that the axially upward thrust does not act on the crankshaft 25, and the mechanical friction loss between the eccentric portion 25a at the upper end of the crankshaft and the axial end surface of the slewing bearing 21c is reduced. Increase can be prevented.

  In such a configuration, when high-pressure working fluid is supplied from an external device to the expander inflow pipe 8 of the expander 4b, the high-pressure working fluid passes through the inflow port 20c and is between the fixed scroll wrap 20a and the orbiting scroll wrap 21a. It flows into the working chamber of the formed expansion mechanism part 22. The high-pressure working fluid that has flowed into the working chamber in the center is expanded by expanding the volume of the working chamber by operating the orbiting scroll 21 due to a pressure difference with the low-pressure working chamber formed on the outer peripheral side. The expanded working fluid flows out of the hermetic container 4a from the expander outflow pipe 9 through the outflow port 20d in the outer peripheral portion.

  At this time, since the orbiting scroll 21 is prevented from rotating by the Oldham ring 24, the center of the orbiting scroll 21 revolves with a constant radius by the eccentric portion 25a of the crankshaft 25. Is converted into mechanical energy called rotation of the crankshaft 25. When the crankshaft 25 is rotated, the sub-compressor 4c is driven, and the roller 3 1 fitted to the eccentric portion 25b of the crankshaft 25 is eccentrically rotated along the cylindrical inner wall surface 30a of the cylinder 30 to act on the working fluid. The compression action is performed.

  FIG. 5 is an enlarged cross-sectional view of a main part of the roller according to the present embodiment, and FIG. The seal ring 41 is a ring-shaped sealing material formed of tetrafluoroethylene resin or the like, has a mating portion 41a, expands the diameter due to the pressure difference between the inside and outside of the roller 31, and follows the radial gap. It has become. The biasing component 42 has an annular shape with an L-shaped cross section and has a plurality of cut-and-raised portions 42a. By this, the seal ring 41 is biased in the axial direction to float from the end face of the roller 31 by a dimension δ. The sealing performance of the end face of the seal ring 41 is ensured even when the internal and external pressure differences do not work. Thereby, the leak in the roller end surface of a subcompressor can be reduced, and compressor efficiency can be improved.

  Next, a back pressure adjusting mechanism that controls the pressure of the back pressure chamber 27 corresponding to the back space of the orbiting scroll 21 of the expander 4b will be described. FIG. 7 is an enlarged cross-sectional view of a main part of the back pressure adjusting mechanism according to the present embodiment. 2 and 7, the back pressure adjusting mechanism 40 includes a back pressure introduction passage 40 a formed in the upper frame 23 so as to communicate with the back pressure chamber 27 and a back pressure introduction passage formed in the lower frame 28. A valve body 40c formed of a circular metal plate that opens and closes 40a, a valve seat 40b that holds the valve body 40c, an elastic member 40d formed of a spiral metal spring that applies a pressing force to the valve body, and a valve A back pressure derivation passage 40e is provided for releasing the pressure in the back pressure chamber 27 when the body 40c is opened. The back pressure outlet passage 40e communicates with a suction passage (suction space) 30e (a low pressure side of the evaporator outlet of the refrigeration cycle) of the sub compressor 4c.

  Here, when the pressure in the back pressure chamber 27 becomes larger than the sum of the suction pressure of the sub-compressor 4c and the elastic force of the elastic member 40d, the valve body 40c is pushed up, and the suction side of the back pressure chamber 27 and the sub-compressor 4c communicates. The pressure in the back pressure chamber 27 decreases. When the pressure in the back pressure chamber 27 decreases, the sum of the suction pressure of the sub-compressor 4c and the elastic force of the elastic member 40d exceeds the force on the back pressure chamber side, and the valve body 40c has the back pressure chamber 27 and the sub-compressor 4c. Shut off from the suction side. According to the back pressure adjusting mechanism 40, the pressure in the back pressure chamber 27 can be easily set to an appropriate pressure by adjusting the elastic force of the elastic member 40d.

  As described above, the back pressure chamber 27 is adjusted so that the pressure does not become excessively high. Therefore, the lubricating oil 7 passes through the bearing clearances of the lower bearing 29 and the slewing bearing 21c in the back pressure chamber 27 and the pressure in the sealed container 4a is reduced. Since the pressure is supplied by the pressure difference from the pressure in the pressure chamber 27, the bearing sliding portion can be reliably lubricated. In parallel, the back pressure chamber 27 is supplied with a high-pressure working fluid dissolved in the oil together with the lubricating oil, and the back pressure adjusting mechanism 40 can appropriately maintain the pressure of the back pressure chamber 27.

  As a result, a back pressure is applied to the end plate 21 b of the orbiting scroll 21, the orbiting scroll 21 is pressed against the fixed scroll 20, and the axial direction in which the orbiting scroll 21 is pressed downward by the pressure in the working chamber of the expansion mechanism 22 by this pressing force. The axial load between the orbiting scroll 21 and the eccentric portion 25a is reduced. In addition, the gap at the tip of the scroll wrap tooth tip is also reduced to ensure sealing performance, enabling high-efficiency operation.

  In addition, since the pressure in the space inside the roller 31 of the sub compressor 4c is the same intermediate pressure as that of the back pressure chamber 27, the pressure difference that is the driving force for internal leakage of the sub compressor is reduced and the compressor efficiency is improved. A positive displacement fluid machine capable of improving the energy efficiency of the refrigeration cycle apparatus can be provided. Further, the back pressure chamber 27 is connected to the low pressure side of the evaporator outlet in the external refrigeration cycle, and the back pressure adjustment mechanism 40 for adjusting the back pressure chamber 27 to a predetermined pressure is provided. Since the amount of lubricating oil mixed in the evaporator can be suppressed, the COP of the refrigeration cycle apparatus 1 can be improved by eliminating the heat transfer performance degradation and pressure loss increase due to the oil, and the sub compressor 4c. It can contribute effectively to lubrication and sealing of the internal working chamber.

  Note that carbon dioxide (R744) as a refrigerant is a natural refrigerant and has a global warming potential (GWP) that is as small as one thousandth that of fluorocarbon refrigerants, and is excellent in terms of environmental protection. 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 7.4 MPa) under the normal operating conditions of the refrigeration air conditioner. Although there is a drawback that the theoretical COP (coefficient of performance) is low, R744 has a large throttle loss in the expansion process compared to the chlorofluorocarbon refrigerant, so that the COP can be greatly improved by recovering the power of the expansion process. Become. Development of an expansion power recovery device equipped with a highly efficient and highly reliable expander is considered to hold the key to commercializing the refrigerant R744 system. Of course, the improvement ratio is somewhat smaller in the CFC-based refrigerant system, but the COP can be improved.

  In the starting method of the positive displacement fluid machine 4 of the present embodiment, the bypass compressor 6 is closed and the main compressor 2 is started, so that the discharge pipe 14 side of the sub compressor 4c first becomes negative pressure and the crankshaft 25 is moved. A rotating torque is generated, and at the same time, pressure is applied to the expander inflow pipe 8 of the expander 4b to drive the expander 4b to rotate. Therefore, a necessary starting torque is secured, and the sub compressor 4c is rotated. Independent startup is possible.

  FIG. 8 is a configuration diagram of a refrigeration cycle including a positive displacement fluid machine according to the second embodiment of the present invention. In the figure, components having the same reference numerals as in FIGS. 1 to 4 are the same components and perform the same functions. This embodiment shows a case where the present invention is applied to a low-pressure chamber type main compressor in which the pressure in the sealed container 2a of the main compressor 2 becomes the suction pressure. Because of the low pressure chamber, the refrigerant compressed by the compression mechanism 2b of the main compressor 2 flows out of the sealed container 2a directly through the discharge pipe 2e and enters the oil separator 12, where the refrigerant and oil are separated. The separated oil is sent through an oil return line 15 to an oil sump at the bottom of the hermetic container 4 a of the positive displacement fluid machine 4.

  When the lubricating oil in the airtight container 4a increases, the oil amount adjusting valve 16a attached to the oil amount adjusting pipe 16 is operated, and the oil is stored in the lower part of the airtight container 2a of the main compressor 2 by the pressure difference. Thus, the oil level of the lubricating oil of the main compressor 2 and the positive displacement fluid machine 4 can be stabilized and the reliability of the system can be ensured. The configuration of the positive displacement fluid machine 4 is the same as that of the high-pressure chamber type main compressor.

  Next, Embodiment 3 of the present invention will be described. FIG. 9 is a longitudinal sectional view of a positive displacement fluid machine according to Embodiment 3 of the present invention, and FIG. 10 is a configuration diagram of a refrigeration cycle provided with the positive displacement fluid machine. In the figure, components having the same reference numerals as in FIGS. 1 to 4 are the same components and perform the same functions. In this embodiment, only the lubrication system of the positive displacement fluid machine 4 is different. In the embodiments so far, the lower end of the crankshaft 25 of the positive displacement fluid machine 4 has been immersed in the lubricating oil 7 stored in the lower part of the sealed container 4a. The end of the crankshaft 25 of the lower bearing 29 in the sub compressor 4c is sealed with a shaft end cover 29a, and an oil supply pipe 17a is connected to the shaft end cover 29a from the outside of the sealed container 4a. The lubricating oil in the sealed container 2a of the main compressor 2 can be directly supplied through the oil supply pipe 17a.

  With such a configuration, it is not necessary to manage the oil level of the lubricating oil 7 inside the positive displacement fluid machine 4, so that the connection piping to the main compressor 2 is simplified, and the arrangement of the positive displacement fluid machine 4 is simplified. The degree of freedom can be greatly increased, and the practicality of the system can be improved.

  In the embodiment described in detail above, the basic cooling operation cycle is given as an example as the refrigeration cycle apparatus 1, but the present invention is not limited to this, and is also used for cooling and heating equipped with an expansion power recovery apparatus. It can be applied to all refrigeration and air conditioning systems such as heat pump room air conditioners, packaged air conditioners, refrigerators and refrigerators, and the system efficiency of these devices can be greatly improved.

It is a refrigerating cycle block diagram provided with the positive displacement fluid machine of Example 1 of this invention. It is a longitudinal section of the positive displacement fluid machine. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. It is BB sectional drawing of FIG. 2 similarly. It is a principal part expanded sectional view of a roller similarly. FIG. 5 is a structural diagram of a sealing component and a biasing component that are also mounted on the roller end surface. It is a principal part expanded sectional view of a back pressure adjustment mechanism similarly. It is a refrigerating cycle block diagram provided with the positive displacement fluid machine of Example 2 of this invention. It is a longitudinal cross-sectional view of the positive displacement fluid machine of Example 3 of the present invention. It is the refrigeration cycle block diagram similarly provided with the positive displacement fluid machine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Refrigeration cycle apparatus, 2 ... Main compressor, 3 ... Radiator, 4 ... Positive displacement fluid machine, 4a ... Sealed container, 4b ... Scroll type expander, 4c ... Rotary subcompressor, 4d ... Crankshaft, 5 DESCRIPTION OF SYMBOLS ... Evaporator, 6 ... Expansion valve, 7 ... Lubricating oil, 8 ... Expander inflow pipe, 9 ... Expander outflow pipe, 10 ... Oil equalizing pipe, 10a ... Oil equalizing pipe, 11 ... Pressure equalizing pipe, 11a ... Pressure equalizing Pipes, 12 ... oil separator, 13 ... sub-compressor suction pipe, 14 ... sub-compressor discharge pipe, 15 ... oil return line, 16 ... oil amount adjusting line, 16a ... oil amount adjusting valve, 20 ... fixed scroll 21 ... Orbiting scroll, 21c ... Orbiting bearing, 22 ... Expansion mechanism part, 23 ... Upper frame, 24 ... Oldham ring, 25 ... Crankshaft, 25a, 25b ... Eccentric part, 25c ... Oil supply path, 26 ... Clamping bolt, 27 ... back pressure chamber, 28 ... lower frame (end plate) ), 28a ... main bearing, 29 ... lower bearing (end plate), 30 ... cylinder, 30e ... suction space, 31 ... roller, 31a ... cylindrical inner peripheral surface of the roller (roller eccentric part bearing, roller inner bearing), 32 DESCRIPTION OF SYMBOLS ... Vane, 33 ... Fastening bolt, 34 ... Assembly bolt, 35 ... Balance weight, 40 ... Back pressure adjustment mechanism, 40a ... Back pressure introduction path, 40b ... Valve seat, 40c ... Valve body, 40d ... Elastic member, 40e ... Back Pressure deriving passage, 41... Seal ring (seal member), 42.

Claims (6)

A scroll expander and a rotary subcompressor are disposed in a closed container in a stacked manner, and both are connected via a crankshaft having two eccentric parts, and the fluid is expanded by the expander, and the subcompressor In a positive displacement fluid machine that drives
The scroll-type expander includes an expansion portion that forms a working chamber by meshing a fixed scroll and a turning scroll, and a frame that fixes the fixed scroll and sandwiches the turning scroll between the fixed scroll and the fixed scroll. Comprising one or more eccentric portions of the crankshaft rotatably fitted to orbiting bearings located at the center of the orbiting scroll,
The rotary sub-compressor includes a roller rotatably fitted to the other eccentric portion of the crankshaft, a vane that reciprocates with the tip in contact with the roller, and partitions the cylinder into a suction chamber and a compression chamber; And an end plate that pivotally supports the crankshaft and closes both end openings of the cylinder,
The crankshaft includes an oil supply path for supplying lubricating oil to a back space of the orbiting scroll constituting the scroll expander,
A positive displacement fluid machine characterized in that the pressure in the back space of the orbiting scroll and the inner space of a roller constituting the rotary sub-compressor is maintained at a pressure intermediate between a high pressure (discharge pressure) and a low pressure (suction pressure). A scroll expander and a rotary subcompressor are disposed in a closed container in a stacked manner, and both are connected via a crankshaft having two eccentric parts, and the fluid is expanded by the expander, and the subcompressor In a positive displacement fluid machine that drives
The scroll-type expander includes an expansion portion that forms a working chamber by meshing a fixed scroll and a turning scroll, and a frame that fixes the fixed scroll and sandwiches the turning scroll between the fixed scroll and the fixed scroll. Comprising one or more eccentric portions of the crankshaft rotatably fitted to orbiting bearings located at the center of the orbiting scroll,
The rotary sub-compressor includes a roller rotatably fitted to the other eccentric portion of the crankshaft, a vane that reciprocates with the tip in contact with the roller, and partitions the cylinder into a suction chamber and a compression chamber; And an end plate that pivotally supports the crankshaft and closes both end openings of the cylinder,
The crankshaft includes an oil supply path for supplying lubricating oil to a back space of the orbiting scroll constituting the scroll expander,
A lubricating oil supply mechanism that communicates the back space of the orbiting scroll and the roller inner space constituting the rotary sub-compressor, and causes the lubricating oil to flow into the back space from the oil supply passage of the crankshaft through the orbiting bearing portion; A positive displacement fluid machine comprising a back pressure adjusting mechanism for setting the back space to a predetermined pressure between the back space and the suction space of the rotary sub-compressor.   The positive displacement fluid machine according to claim 1 or 2, wherein a seal member is disposed on an end surface portion of a roller constituting the rotary subcompressor.   The positive displacement fluid machine according to any one of claims 1 to 3, wherein the slewing bearing and the lower bearing positioned at both ends of the crankshaft are slide bearings, and the diameters of both the bearings are substantially the same.   The positive displacement fluid machine according to any one of claims 1 to 3, wherein the main bearing of the crankshaft and the roller inner bearing are rolling bearings.   6. The positive displacement fluid machine according to claim 1, wherein the fluid is connected to a refrigeration cycle using carbon dioxide as a refrigerant.

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