JP2009074485A - Scroll compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent vibration of a muffler externally arranged to a compressor shell so as to avoid stress acting on a discharge pipe or the like. <P>SOLUTION: The scroll compressor 1 includes in a closed shell 22 a fixed scroll 3 and a swing scroll 4 that swings and defines a compressor chamber 19 between the fixed scroll 3 and itself. A discharge port 37 for discharging compressed fluid that has been compressed in the compressor chamber 19 is formed in the fixed scroll 3. One end of the discharge pipe 7 is connected to the discharge port 37 of the fixed scroll 3. The silencing and oil separating muffler 2 having an inlet port 15A to which a shell outer end portion of the discharge pipe 7 is connected, an oil discharge port 17A and a compressed fluid outlet port 16A, is directly secured to the outer surface of the closed shell 22. There provided is an oil return passage 14 for connecting the oil discharge port 17A of the muffler 2 and a suction port 23 of the closed shell 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scroll compressor mounted on an air conditioner, a refrigerator, a water heater, or the like.

  Conventionally, as a scroll compressor of this type, first, a high-pressure refrigerant gas compressed in a compression chamber between an orbiting scroll and a fixed scroll is configured not to leak into a low-pressure side space, and then in the compressor shell. The space above the fixed scroll is a muffler chamber, and secondly, the muffler chamber is placed in the compressor shell so that the high-pressure refrigerant gas discharged from the discharge port of the fixed scroll does not act on the compressor shell. What is provided is known. Thirdly, as in Patent Document 1 below, the compressor shell has an oil separation function in the high-pressure muffler chamber, and has an oil return passage that returns the lubricating oil separated in the high-pressure muffler chamber to the low-pressure side space. And fourthly, there is known an oil separator provided outside the compressor shell without having an oil separation function in the high-pressure muffler chamber.

JP-A-6-10835 (paragraphs [0010] to [0018], FIGS. 1 to 3)

  In each of the prior arts described above, in the first scroll compressor in which the space above the fixed scroll in the compressor shell is the muffler chamber, the high-pressure refrigerant gas compressed in the compression chamber between the swing scroll and the fixed scroll is compressed. Because it acts directly on the machine shell, the shell wall thickness of the muffler chamber must be increased, and the problem of increased total weight and increased price could not be addressed. In addition, the second scroll compressor that does not have an oil separation function in the high-pressure muffler chamber described above needs to install an oil separator separately, so that it is necessary to increase costs and secure an installation location. And since the 3rd scroll compressor (patent document 1) which has an oil separation function in a compressor shell becomes a structure where the high-pressure side space and low-pressure side space in a compressor shell bypass by an oil passage, -The high-pressure refrigerant gas flows into the low-pressure side space, leading to a decrease in compression efficiency. Furthermore, in the 4th scroll compressor which installed the oil separator outside the compressor, since the compressor shell and the oil separator are connected by the pipe, the stress acts on the pipe which transmits the vibration and the noise There was a risk of occurrence or damage to piping.

  The present invention has been made to solve the above-described problems, and suppresses the stress acting on the discharge pipe and the like by suppressing the vibration of the muffler provided outside the compressor shell, and also provides a sound deadening function and an oil. An object is to obtain a scroll compressor having a compact structure while having a separation function.

In order to solve the above-mentioned problems, a scroll compressor according to the present invention forms a compression chamber between a fixed scroll fixed to the inner wall surface of the shell and a fixed scroll in a hermetic shell and swings and swings. An oscillating scroll, a drive mechanism unit that swings and oscillates the oscillating scroll, and an oil supply unit that supplies lubricating oil to the drive mechanism unit and the compression chamber are provided to discharge the compressed fluid compressed in the compression chamber. A scroll compressor in which a discharge port is formed in a fixed scroll and a discharge pipe for guiding a fluid to be compressed from the discharge port to the outside of the hermetic shell is provided, and an inlet to which an outer end portion of the shell of the discharge pipe is connected And a muffler that has an oil discharge port for discharging the separated lubricating oil and an outlet for the compressed fluid to separate and mute the lubricating oil from the compressed fluid and is directly fixed to the outer surface of the sealed shell. Toru In is provided that is characterized in that oil return passage connecting the inlet of the compressed fluid of the sealed shell oil discharge port of the muffler is provided.

The scroll compressor according to the present invention includes a fixed scroll fixed to the inner wall surface of the shell in the hermetic shell, and an orbiting scroll that swings and swings by forming a compression chamber between the fixed scroll, The muffler for silencing the compressed fluid guided from the discharge port of the fixed scroll through the discharge pipe to the outside of the sealed shell and separating the lubricating oil from the compressed fluid is directly fixed to the outer surface of the sealed shell. Therefore, the frequency of vibration transmitted from the sealed shell to the muffler during the compressor operation can be made the same. Thereby, generation | occurrence | production of the stress concerning the discharge pipe which connects a fixed scroll and sealing shell, and a muffler can be suppressed. In addition, a muffler with an oil separation structure is arranged outside the sealed shell that can secure a large facility space, so that a large facility space can be used while adopting a compact configuration with both a silencing function and an oil separation function. Thus, an oil return amount control configuration and an oil temperature control configuration can be provided. In addition, since the discharge pipe connected to the discharge port of the fixed scroll is connected to the muffler outside the sealed shell, the structure of the low-pressure shell is such that the high-pressure compressed fluid does not directly act on the inner wall of the sealed shell. A hermetic shell can be used, and the total weight can be reduced and the price can be reduced.

Embodiment 1 FIG.
1 is a configuration diagram including a partial cross section showing a scroll compressor according to Embodiment 1 of the present invention, and FIG. 2 is a longitudinal sectional view showing a muffler of the scroll compressor according to Embodiment 1 of the present invention.
In each figure, the scroll compressor 1 includes a cylindrical middle shell 9 arranged in a bowl shape, an upper shell 8 that is secured to the upper surface opening of the middle shell 9 by welding or the like, and a lower surface opening of the middle shell 9. It has a sealed shell 22 composed of a lower shell 10 that is fixed by welding or the like. In this sealed shell 22, the upper frame 24 is fixed to the upper part of the inner shell wall surface 25 of the middle shell 9, and the base plate portion 3 </ b> A of the fixed scroll 3 is fixed to the upper outer peripheral edge of the upper frame 24. Plate-like spiral teeth 3B are suspended from the lower surface of the base plate portion 3A of the fixed scroll 3. The swing scroll 4 is slidably supported on the upper surface of the upper frame 24 below the fixed scroll 3, and the plate-like spiral teeth of the fixed scroll 3 are mounted on the upper surface of the base plate portion 4 A of the swing scroll 4. A plate-like spiral tooth 4 </ b> B that forms a compression chamber 19 is formed between 3 </ b> B and 3 </ b> B.

A boss portion is suspended from the center of the bottom surface of the base plate portion 4A of the orbiting scroll 4, and an Oldham ring 11 is mounted on the outer periphery of the boss portion. An eccentric shaft portion 12B formed at the upper end of the main shaft 12 is inserted into the shaft hole formed in the lower surface of the boss portion of the orbiting scroll 4, and the eccentric shaft portion of the main shaft 12 is inserted into the slider 26 provided in the shaft hole. 12B comes into sliding contact. The upper portion of the main shaft 12 is pivotally supported by a bearing portion of the upper frame 25, and the lower portion of the main shaft 12 is rotated by a thrust bearing 29 of the lower frame 28 fixed to the lower portion of the shell inner wall surface 25 of the middle shell 9. Thrust is supported freely. A space below the upper frame 24 in the middle shell 9 is a low-pressure side space, to which a suction pipe 6 for taking in refrigerant gas is connected. A stator of the electric motor 25 is fixed to a shell inner wall surface 25 between the upper and lower frames 24 and 28 in the middle shell 9. A rotor of an electric motor 27 is fixed to the main shaft 12 at a position facing the stator of the electric motor 25. The oscillating scroll 4 swings with respect to the fixed scroll 3 by the drive mechanism unit 20 including the boss portion of the oscillating scroll 4, the slider 26, the Oldham ring 11, the eccentric shaft portion 12 </ b> B of the main shaft 12, and the electric motor 27. It is supposed to be.

The main shaft 12 is formed with an oil passage 12A penetrating vertically. The lower end opening of the oil passage 12 </ b> A communicates with an oil pump 13 connected to the lower end of the main shaft 12. The upper end opening of the oil passage 12 </ b> A communicates with the shaft hole of the boss portion of the orbiting scroll 4. On the bottom surface of the lower shell 10 is an oil storage space 30 in which the lubricating oil J is stored. Lubricating oil J in the oil storage space 30 is supplied to the drive mechanism unit 20 and the compression chamber 19 by an oil supply unit 21 including the oil pump 13 and the oil passage 12 </ b> A of the main shaft 12.

A discharge port 37 for discharging a refrigerant (for example, carbon dioxide (an example of a fluid to be compressed)) compressed in the compression chamber 19 is formed in the center of the plane of the base plate portion 3A of the fixed scroll 3. An internal muffler 5 is provided on the upper surface of the base plate portion 3 </ b> A of the fixed scroll 3 so as to enclose the discharge port 37. One end of a discharge pipe 7 is connected to the discharge port of the internal muffler 5. The discharge pipe 7 passes through the upper shell 8, and the other end (shell outer end portion) is disposed outside the sealed shell 22 so as to guide the carbon dioxide gas from the discharge port 37 to the outside of the sealed shell 22. . A suction port to the compression chamber 19 is formed so as to penetrate vertically through the upper frame 24 at a position below the peripheral edge of the orbiting scroll 4.

  The outer muffler (muffler) 2 includes a muffler shell 18 formed in a cylindrical shape with both upper and lower ends narrowed into a tapered shape, an inflow pipe 15 connected in a tangential direction to the outer peripheral surface of the muffler shell 18, and an upper tapered portion of the muffler shell 18. An outflow pipe 16 that is inserted into the shell and fixed coaxially with the shell axis, and an oil discharge pipe 17 that is fixed through the apex of the lower taper portion of the muffler shell 18. Thus, the lubricant oil J is separated from the refrigerant and silenced in the muffler shell 18. The other end of the discharge pipe 7 is connected to the inlet 15 </ b> A of the inflow pipe 15. The outlet 16A of the outflow pipe 16 is connected by piping so that the refrigerant gas separated from the lubricating oil J flows out to the high pressure side of the refrigerant circuit. The oil discharge port 17 </ b> A of the oil discharge pipe 17 is connected to the suction port 23 of the sealed shell 22 via the oil return passage 14. The muffler shell 18 of the external muffler 2 is directly fixed to the outer surface of the hermetic shell 22. The term “direct fixing” as used in the present invention refers to a member having a structure in which the vibration of the sealing shell 22 is not amplified and transmitted to the muffler shell 18 as well as when the sealing shell 22 and the muffler shell 18 are directly attached by welding or the like. This includes the case of connecting via a sheet metal or the like. In this case, it is important to arrange the muffler shell 18 of the external muffler 2 so as not to contact other members.

Next, the operation will be described.
In the scroll compressor 1 configured as shown in FIG. 1, when a power supply terminal (not shown) provided in the middle shell 9 is energized, torque is generated in the stator and rotor of the motor 27, and the main shaft 12 rotates. To do. As a result, the orbiting scroll 4 rotatably mounted on the eccentric shaft portion 12 </ b> A of the main shaft 12 revolves through the Oldham ring 10 to form a compression chamber 19 with the fixed scroll 3. As a result, carbon dioxide gas is sucked from the suction pipe 6 into the low pressure side space in the sealed shell 22. The carbon dioxide gas that has flowed into the low pressure side space in the sealed shell 22 flows into the compression chamber 19 from the suction port of the upper frame 24 and is compressed, and then passes from the discharge port 37 through the internal muffler 5 and through the discharge pipe 7. It is discharged out of the sealed shell 22.

Since the scroll compressor 1 has a structure in which high-pressure carbon dioxide gas is discharged out of the shell through the internal muffler 5 and the discharge pipe 7, the hermetic shell 22 has a low-pressure shell configuration. Therefore, the high-pressure carbon dioxide gas does not directly act on the sealed shell 22 (particularly the upper shell 8). As a result, the thickness of the sealed shell 22 (particularly the upper shell 8) can be reduced, and the manufacturing cost can be reduced and the total weight of the compressor can be reduced. Furthermore, since the scroll compressor 1 of this embodiment uses carbon dioxide as a refrigerant, the increase in shell thickness due to the increase in operating pressure is significant compared to other refrigerants, and therefore high pressure is not applied. The advantage of using the low-pressure shell type hermetic shell 22 is increased.

  On the other hand, the lubricating oil J such as refrigerating machine oil ascends in the oil passage 12 </ b> A of the main shaft 12 by the action of the oil pump 13 and reaches the drive mechanism unit 20, and a part of the lubricating oil J is sucked into the compression chamber 19. Compressed together with the refrigerant gas and discharged outside the shell. The refrigerant gas and the lubricating oil J flow into the external muffler 2 through the discharge pipe 7.

In the scroll compressor 1, since the hermetic shell 22 and the outer muffler 2 are directly fixed, the hermetic shell 22 and the outer muffler 2 simultaneously vibrate at the same frequency during the compressor operation. Therefore, no stress is generated in the discharge pipe 7 connecting the sealed shell 22 and the external muffler 2, and the risk of the discharge pipe 7 being damaged can be reduced.

  By the way, the lubricating oil J discharged from the external muffler 2 passes through the oil return passage 14 and is returned to the suction port 23 of the sealed shell 22, but includes a muffler having an oil separation function inside the sealed shell (Patent Document 1). In this scroll compressor 1, the amount of oil returned when the lubricating oil J is returned to the sealed shell 22 by disposing the external muffler 2 having an oil separation function outside the sealed shell 22. It is possible to control the lubricating oil J, such as adjusting the temperature or lowering the temperature of the lubricating oil J to prevent deterioration of the compressor performance.

On the other hand, the refrigerant gas that has flowed into the external muffler 2 from the inflow pipe 15 swirls and spirals down along the inner peripheral wall of the muffler shell 18. Due to the swivel and descent, a cyclone effect occurs in which oil mist (fine particles of the lubricating oil J) subjected to centrifugal force collides with and adheres to the inner peripheral surface of the muffler shell 18, and the oil mist suspended in the refrigerant gas Is gradually separated from the refrigerant gas. The refrigerant gas from which the lubricating oil J has been separated is discharged from the outflow pipe 16 to the refrigerant circuit, and the lubricating oil adhering to the inner wall surface of the muffler shell 18 descends the inner wall surface due to the action of gravity and is discharged from the discharge pipe 17.

As described above, the oil separation function is provided inside the outer muffler 2 and the length of the oil return passage 14 can be shortened by directly fixing the outer muffler 2 to the sealed shell 22. Moreover, since it is not necessary to install an oil separator separately, the compact scroll compressor 1 can be provided.

Embodiment 2. FIG.
FIG. 3 is a circuit configuration diagram showing a water heater to which the scroll compressor according to the second embodiment is applied.
As shown in FIG. 3, the hot water heater includes a scroll compressor 1 having a variable capacity, a high-pressure side heat exchanger (condenser) 31, an expansion valve 32, and a low-pressure side heat exchanger (evaporator) 33. The refrigerant circuit is sequentially connected in an annular manner through the line 34. An external muffler 2 is directly attached directly to the outer surface of the hermetic shell 22 of the scroll compressor 1. The high-pressure side heat exchanger 31 is passed with a water pipe 35 through which water that is heated by heat exchange with the refrigerant in the refrigerant circuit flows. An oil cooling heat exchanger (an example of an oil cooling device) 36 that preheats water is disposed on the upstream side in the flow direction of the high pressure side heat exchanger 31 in the water pipe 35. The oil cooling heat exchanger 36 passes through an oil return passage 14 that connects the oil discharge port 17A of the external muffler 2 and the suction port 23 of the sealed shell 22 of the scroll compressor 1. The lubricating oil separated from the refrigerant gas by the external muffler 2 passes through the oil return passage 14 and enters the oil cooling heat exchanger 36 to heat the water and cool itself. Between the oil cooling heat exchanger 36 in the oil return passage 14 and the suction port 23 of the scroll compressor 1, an oil flow amount adjusting device for adjusting the amount of the lubricating oil J flowing in the oil return passage 14 ( For example, an electronic linear expansion valve (LEV) 39 is provided. In the oil storage space in the lower part of the external muffler 2, an oil level detecting device 40 for detecting the oil level of the lubricating oil J separated and stored from the refrigerant gas is provided. Further, an oil return amount control device 41 that adjusts the oil return amount of the lubricating oil J to the suction port 23 of the sealed shell 22 by controlling the oil flow amount adjusting device 39 is provided. The oil return amount control device 41 is embodied by a microcomputer mainly composed of, for example, a central processing unit (CPU), a memory, a data bus, and the like.

  Next, the basic operation of the water heater according to the second embodiment will be described. The high-temperature refrigerant gas compressed by the sealed shell 22 of the scroll compressor 1 is silenced by the external muffler 2 and separated from the lubricating oil J, and then flows into the high-pressure side heat exchanger 31. In the high-pressure side heat exchanger 31, the refrigerant is cooled by exchanging heat with water supplied from the water pipe 35 and then cooled by the expansion valve 32 to become a gas-liquid two-phase refrigerant and flow into the low-pressure side heat exchanger 33. . In the low pressure side heat exchanger 33, the refrigerant exchanges heat with air to be gasified and returns to the suction port 23 of the sealed shell 22. By such a refrigeration cycle operation, the water flowing through the water pipe 35 is heated to become hot water, and then stored in the hot water storage tank 38 for use.

By the way, the high-temperature lubricating oil J separated by the external muffler 2 flows out into the oil return passage 14, is cooled by exchanging heat with the water in the water pipe 35 by the oil cooling heat exchanger 36, and is then cooled. It returns to the inlet 23 of the sealing shell 22 via. In this case, when the high-temperature lubricating oil J separated by the external muffler 2 is directly returned to the closed shell 22, the temperature inside the closed shell 22 rises and the refrigerant gas is warmed, so that the density of the refrigerant decreases. However, in a general scroll compressor, the compression chamber 19 formed between the fixed scroll 3 and the orbiting scroll 4 always takes in a constant volume of refrigerant at a time, so that the density becomes small when the temperature of the suction refrigerant is high. As a result, the mass flow rate decreases, leading to a decrease in the performance of the compressor itself. On the other hand, in the scroll compressor 1 of the present embodiment, the lubricating oil J returned to the hermetic shell 22 does not heat and expand the refrigerant gas, reducing the compression efficiency and reliability due to overheating. Can be prevented. In addition, since the lubricating oil J separated by the external muffler 2 is used for preheating water by heat exchange, the application of the scroll compressor 1 provides a water heater with high energy efficiency without wasting heat. can do.
Incidentally, as an example of cooling of the refrigerator oil by the oil cooling device 36, if the discharge temperature of the scroll compressor 1 is 100 ° C. to 120 ° C., the oil is returned to the refrigerant gas and the lubricating oil J after being separated by the external muffler 2 Similarly, the temperature of the lubricating oil J flowing through the passage 14 is also 100 ° C. to 120 ° C. Since the feed water temperature before being heated as hot water is 10 ° C. to 30 ° C., the temperature of the lubricating oil J can be lowered from 10 ° C. to 30 ° C. by the oil cooling device 36.

  In the external muffler 2, the lubricating oil J separated from the refrigerant gas is stored at the bottom of the external muffler 2, and the oil return amount is determined by the valve opening degree of the oil flow adjusting device 39 and scrolls from the bottom of the external muffler 2. Oil is returned to the suction port 23 of the compressor 1. On the other hand, the amount of the lubricating oil J contained in the refrigerant gas discharged from the scroll compressor 1 varies depending on the compressor operating frequency and the compressor suction pressure. Generally, the higher the operation frequency, the higher the compressor suction pressure. It will increase. Further, when the valve opening degree of the oil flow adjusting device 39 is small, the oil return amount decreases, and when the valve opening degree is large, the oil return amount increases. That is, if the valve opening is excessive with respect to the amount of the lubricating oil J discharged from the scroll compressor 1, not only the lubricating oil J is returned excessively from the bottom of the external muffler 2, but also the high-temperature and high-pressure refrigerant. There is an inconvenience that the gas returns to the suction side of the sealed shell 22 through the oil return passage 14 and causes overheating and a reduction in efficiency of the scroll compressor 1. Conversely, if the valve opening is too small relative to the amount of the lubricant oil J discharged from the scroll compressor 1, the amount of lubricant oil J returned from the bottom of the external muffler 2 decreases, and the lubricant oil J is reduced. There is an inconvenience that the external muffler 2 is excessively stored, the lubricating oil J inside the sealed shell 22 is depleted, and the internal mechanism portion of the compressor cannot be lubricated, resulting in a compressor failure. On the other hand, the water heater of this embodiment determines the target valve opening of the oil flow adjusting device 39 from the operating frequency, operating pressure, etc. of the scroll compressor 1, and adjusts the valve opening to return it appropriately. Oil quantity can be realized.

  That is, the water heater of this embodiment can be controlled to an optimum oil return amount that matches the operating conditions, such as increasing the oil return amount during high-speed operation of the compressor and decreasing the oil return amount during low-speed operation. Thereby, the oil level of the lubricating oil J in the external muffler 2 is always ensured within an appropriate level range. As a result, when the variable capacity scroll compressor 1 is used, the external muffler 2 is used when the compressor operating capacity is large, such as when a capillary tube having an inner diameter suitable for the vicinity of the lower limit value of the appropriate oil level range is selected. Compressor operating capacity, such as the problem that the lubricant oil J accumulates too much and the oil level exceeds the appropriate oil level range, or when a capillary tube with an inner diameter that fits near the upper limit of the oil level range is selected. Therefore, the problem that the lubricating oil J in the external muffler 2 becomes empty and the high-temperature / high-pressure refrigerant gas returns to the suction side of the sealed shell 22 through the oil return passage 14 can be avoided.

In addition, although the example (FIG. 3) which applied the scroll compressor 1 to the hot water heater was shown above, the said scroll compressor 1 was used for the air heater which heats air with the high voltage | pressure side heat exchanger of a refrigerant circuit. The air may be preheated on the upstream side in the air flow direction of the high pressure side heat exchanger. In the above, the muffler having a so-called cyclone type oil separation structure in which the compressed fluid is swirled in the muffler shell and the lubricating oil is separated from the compressed fluid by the centrifugal force is exemplified. It is also possible to employ an oil separation structure that separates lubricating oil by colliding with a mesh body or baffle plate. In the above, the example in which the internal muffler 5 is provided in the hermetic shell 22 is shown, but the internal muffler 5 is omitted, and the discharge port 37 of the fixed scroll 3 and the inlet 15A of the external muffler 2 are connected by the discharge pipe 7. You may make it connect directly. Furthermore, when there is no significant fluctuation in the operating capacity and the emphasis is placed on cooling the separated lubricating oil, a capillary tube may be used instead of the electronic linear expansion valve as the oil flow amount adjusting device. The fluid to be compressed is not limited to the carbon dioxide, but may be a fluid used for a general air conditioner such as a fluorine-based refrigerant, ammonia, or the like.

It is a block diagram including the partial cross section which shows the scroll compressor in Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the muffler of the scroll compressor in Embodiment 1 of this invention. It is a circuit block diagram which shows the water heater to which the scroll compressor in Embodiment 2 of this invention is applied.

Explanation of symbols

1 Scroll compressor 2 External muffler (muffler)
DESCRIPTION OF SYMBOLS 3 Fixed scroll 4 Swing scroll 7 Discharge pipe 14 Oil return path 15A Inlet 16A Outlet 17A Outlet 19 Compression chamber 20 Drive mechanism part 21 Oil supply part 22 Sealed shell 23 Inlet 25 Shell inner wall surface 36 Oil cooling heat exchanger (Oil cooling device)
37 Discharge port 39 Oil flow rate adjusting device 40 Oil level detecting device 41 Oil return amount control device J Lubricating oil.

Claims (4)

A fixed scroll fixed to the inner wall surface of the shell in the hermetic shell, a swing scroll that swings and swings by forming a compression chamber between the fixed scroll, and a drive mechanism that swings and swings the swing scroll And an oil supply section that supplies lubricating oil to the drive mechanism section and the compression chamber, and a discharge port that discharges the compressed fluid compressed in the compression chamber is formed in the fixed scroll, and the discharge port A scroll compressor provided with a discharge pipe for guiding a fluid to be compressed from the outside of the hermetic shell, an inlet to which an outer end portion of the shell of the discharge pipe is connected, and discharging the separated lubricating oil A muffler having an oil discharge port and an outlet for the compressed fluid that separates and silences the lubricating oil from the compressed fluid, and is directly fixed to the outer surface of the hermetic shell. Scroll compressor wherein the oil return passage connecting the mouth and the intake port of the compressed fluid of the sealed shell is provided. The scroll compressor according to claim 1, further comprising an oil cooling device for cooling the lubricating oil separated from the fluid to be compressed by the muffler. Detected by an oil level detecting device that detects the level of lubricating oil in the muffler, an oil flow adjusting device that adjusts the amount of lubricating oil flowing through the oil return passage, and the oil level detecting device. An oil return amount control device that adjusts the oil return amount of the lubricating oil to the suction port of the sealed shell by controlling the oil flow amount adjusting device according to the oil level in the muffler. The scroll compressor according to claim 1 or 2, characterized by the above-mentioned. The scroll compressor according to any one of claims 1 to 3, wherein the fluid to be compressed is carbon dioxide.

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