KR101002472B1 - Multi-stage rotary compressor - Google Patents

Abstract

The present invention relates to a multistage rotary compressor. In the multi-stage rotary compressor of the present invention, the multi-stage rotary compressor having a plurality of compression units in the inner space of one casing, in the case of the power operation mode, the plurality of compression units independently suck and compress the refrigerant to the inner space of the casing On the other hand, in the saving operation mode, the refrigerant compressed in one stage by the second compression unit is compressed in two stages by the first compression unit and discharged into the inner space of the casing, thereby allowing the capacity to be varied and the refrigerant. In the saving mode to reduce the amount of discharge, it is possible to have a power saving effect while using all the plurality of compression units, and to minimize the unit cost by simplifying the manufacturing process.

Description

Multi-stage rotary compressor {MULTI-STAGE ROTARY COMPRESSOR}

1 is a longitudinal sectional view showing a first embodiment of the present invention;

2 is an enlarged cross-sectional view showing the main part of a first embodiment of the present invention;

3 is a cross-sectional view showing operation in a power mode according to the first embodiment of the present invention;

4 is a cross-sectional view showing the operation in the saving mode according to the first embodiment of the present invention;

5 is an enlarged cross-sectional view showing the main part of a second embodiment of the present invention;

6 is a cross-sectional view showing operation in power mode according to a second embodiment of the present invention;

7 is a cross-sectional view showing operation in a saving mode according to a second embodiment of the present invention;

8 is an enlarged cross-sectional view showing the main part of a third embodiment of the present invention;

9 is a cross-sectional view showing operation in a power mode according to a third embodiment of the present invention;

10 is a cross-sectional view showing operation in a saving mode according to a third embodiment of the present invention;

** Description of symbols for the main parts of the drawing **

100: casing 110: discharge tube

130: accumulator 200: drive unit

210: stator 220: rotor

230: rotating shaft 300: the first compression unit

310: first cylinder 320: upper bearing                 

330: first compression space 340: first rolling piston

350: intermediate bearing 351: actuator insertion groove

352: free space 360: first discharge hole

370: first discharge valve 400: second compression unit

410: second cylinder 430: second compression space

440: second rolling piston 450: lower bearing

460: second discharge hole 470: second discharge valve

500: refrigerant flow path 510: first flow path

520: 2nd flow path 600, 800, 900: actuator (2nd valve)

610, 810, 910: valve body 611, 911: through passage

612, 912: stepped portions 620, 820, 920: spring

630, 830, and 930: electromagnet 710: first suction pipe

715: control valve (first valve) 730: second suction pipe

740: chamber 811: refrigerant flow path

812: body portion 813: upper stepped portion

814: lower stepped portion 815: connection hole

The present invention relates to a rotary compressor, and more particularly, to a multi-stage rotary compressor having a plurality of compression units, which is inexpensive and can easily vary the compressor capacity.

In general, a compressor receives power from a power generating device such as an electric motor and compresses working gas to increase pressure by applying compression work to air, refrigerant, or other special gases, and is widely used throughout the industry. Compressors can be classified into volumetric and turbo type, depending on how the compression is achieved. Positive displacement compressors have a compression method that increases pressure through volume reduction, and a turbo compressor converts gas kinetic energy into pressure energy to achieve compression. Rotary compressors among volumetric compressors are mainly applied to air conditioners such as air conditioners, and in recent years, rotary compressors also require products that can vary in capacity in response to a trend of varying functions of air conditioners.

Rotary compressors have used CFC-based refrigerants until now. However, these refrigerants are regulated because they destroy the ozone layer and cause global warming, and research and development of alternative refrigerants instead of the existing refrigerants are actively performed. Carbon dioxide is expected as an alternative refrigerant. Moreover, the problem of global warming is not just a replacement for refrigerants, but also leads to a task of increasing the energy efficiency of equipment. This is because much of the electrical energy is still obtained using fossil fuels, because the carbon dioxide produced when burning fossil fuels is a major culprit of global warming.                         

In the compressor, which is the heart of the refrigeration system, a natural concern is how to apply alternative refrigerants harmless to the global environment to the existing compressors without any loss of performance. In view of this, in recent years, a multi-stage rotary compressor having a plurality of compression units has been widely introduced as a compressor having a variable capacity and using a replacement refrigerant.

In this multi-stage rotary compressor, a rolling piston which is eccentrically coupled to the rotating shaft sucks and compresses the refrigerant while discharging the cylinder while pivoting in a cylinder. If you want to achieve the effect of power saving while reducing the load and reducing the capacity (hereinafter, save mode), you can shut off the refrigerant sucked into some compression units or fix the vane with a piece after retreating. It is known to implement a variable capacity of the refrigerant through a variable speed by eliminating the partition of the rolling piston so that the idling does not compress the refrigerant or by using an inverter motor equipped with a control drive as a driving unit.

However, the structure and operation method of the conventional rotary compressor as described above can not implement various changes in capacity when blocking the refrigerant intake by the compression unit, and the method of fixing the vane retreat in the saving mode is a separate part such as a piece and the like. In addition to the need for space for mounting parts and the increase in the number of manufacturing processes, the impact of the pieces on the vanes repeatedly may damage the surface over time, and may cause reliability problems such as wear or foreign matter. There was.                         

In addition, there is also a problem in that the efficiency of the compressor is lowered when idling or blocking the intake of the refrigerant or because some compression units are not used.

In addition, when an inverter motor is used as the drive unit, there is a problem that the manufacturing cost is higher than that of the constant speed motor.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is not only to change the capacity according to the change of the room temperature, but also to prevent damage to parts and minimize manufacturing costs. In providing a multi-stage rotary compressor.

In addition, an object of the present invention is to provide a multi-stage rotary compressor that can have a power saving effect while using all of a plurality of compression units in a saving mode for reducing a discharge amount of a refrigerant.

In order to achieve the object of the present invention, there is provided a first compression unit and a second compression unit having a different compression space in the inner space of one casing, the first compression unit and the second compression unit according to the operation mode A multi-stage rotary compressor that independently sucks and compresses refrigerant to be discharged into the inner space of the casing, or compresses the refrigerant compressed by the first stage in the second compression unit to the stage of the second compression by compressing the refrigerant in the first compression unit in two stages. to provide.
In addition, one casing having a closed inner space; A first compression unit installed in the inner space of the casing to form a first compression space; And a second compression unit which is separated from the first compression unit and installed in the inner space of the casing and forms a second compression space. The second compression unit is opened on the suction side of the first compression unit during power operation, A closed first valve is provided, and the discharge side of the second compression unit communicates with the discharge side of the second compression unit and the inner space of the casing during power operation, while the discharge side and the second compression unit of the second compression unit during the saving operation. A multistage rotary compressor provided with a second valve communicating with the suction side of a first compression unit is provided.

Hereinafter, the multi-stage rotary compressor according to the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings.

1 is a longitudinal sectional view showing a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing the main part of a first embodiment of the present invention.

As shown therein, the multi-stage rotary compressor of the present invention includes a casing 100 having a sealed space therein; A driving unit 200 mounted to the casing 100 to generate a driving force; A first compression unit 300 and a second compression unit 400 receiving a driving force from the drive unit 200 to compress the refrigerant; A first suction pipe 710 for guiding the refrigerant to the first compression unit 300; A control valve 715 mounted on the first suction pipe 710 to control suction refrigerant; A second suction pipe 730 for guiding the refrigerant to the second compression unit 400; A chamber 740 for temporarily storing the refrigerant discharged from the second compression unit 400 by covering the second discharge valve 470 intermitting the discharge refrigerant of the second compression unit 400; The chamber 740 and the casing 100 communicate with each other by passing through the first and second compression units 300 and 400, and further, the chamber 740 and the first compression unit 300. A refrigerant passage 500 in communication with the compression space 330; Is installed on the refrigerant passage 500 to guide the refrigerant in the chamber 740 into the casing 100 or to selectively cool the refrigerant in the chamber 740 to the compression space 330 of the first compression unit 300. It is characterized in that it comprises a guide actuator 600.

The casing 100 is installed through the discharge pipe 110, the first suction pipe 710, and the second suction pipe 730.

The drive unit 200 is fixed to the inside of the casing (100) for applying power from the outside and the stator 210 is disposed while leaving a predetermined gap inside the stator 210 to rotate while interacting with the stator The rotor 220 and the rotor 220 are formed integrally to transmit the driving force to each compression unit (300, 400) consists of a rotating shaft 230 having two eccentric parts. The drive unit 200 is preferably composed of a constant speed motor. Constant speed motors generally have the advantage of being less expensive than inverter motors with control drives.

The compression unit is composed of a first compression unit 300 and the second compression unit 400, the first compression unit 300 is formed in an annular first cylinder 310 to be installed in the casing 100 ), The upper bearing 320 and the intermediate bearing 350 to radially support the rotating shaft 230 while forming the first compression space 330 together to cover the upper and lower sides of the first cylinder 310, and The first rolling piston 340 is inserted into the upper eccentric portion of the rotary shaft 230 to compress the refrigerant while turning in the first compression space 330 of the first cylinder 310, and the first rolling piston 340 A first vane configured to be radially movably coupled to the first cylinder 310 to be in pressure contact with the outer circumferential surface so as to partition the first compression space 330 of the first cylinder 310 into a first suction chamber and a first discharge chamber, respectively; Not shown) and the opening and closing at the tip of the first discharge hole 360 formed in communication with the first discharge chamber in the upper bearing 320 The first discharge valve 370 may be configured to be coupled to control discharge of the refrigerant discharged from the first discharge chamber.

The second compression unit 400 is formed in an annular shape and positioned below the first cylinder 310 and in contact with the intermediate bearing 350, and an upper surface of the second cylinder 410. A lower bearing 450 supporting the rotating shaft 230 in the radial and axial directions while being coupled to the second inner space 430 together with the lower eccentric portion of the rotating shaft 230 to be rotatably coupled to the Compression of the second rolling piston 440 located in the second compression space 430 of the second cylinder 410, and the radial direction to the second cylinder 410 to be in pressure contact with the outer peripheral surface of the second rolling piston 440 A second vane (not shown) which is movably coupled to each other and divides the second compression space 430 of the second cylinder 410 into a second suction chamber and a second discharge chamber, and one side of the lower bearing 450. A second coupling coupled to the tip of the second discharge hole 460 formed to communicate with the second discharge chamber The discharge valve 470 is formed.

The volume of the first compression space 330 of the first cylinder 310 and the volume of the second compression space 430 of the second cylinder 410 may be the same, but different from each other for more careful capacity change. It is preferable to form.

The first suction pipe 710 and the second suction pipe 730 are connected to an accumulator 130 whose suction side separates gaseous liquid from the refrigerant. The accumulator 130 sends only gas components to the first suction tube 710 and the second suction tube 730 after gas-liquid separation from one accumulator tube 135 that receives a refrigerant from the outside. One of the first or second suction pipes may be directly connected to the compression unit without passing through the accumulator 130.

The control valve 715 is preferably composed of a two way valve (2 way valve). The control valve 715 may be connected to the microprocessor for the control of the valve.

The chamber 740 is installed in a lower part of the second compression unit 400 (more precisely, lower part of the lower bearing 450) to maintain airtightness so that refrigerant does not leak. In addition, the chamber 740 is preferably designed to simultaneously perform the role of a muffler (muffler) to realize a low noise during operation of the compressor.

As shown in FIG. 2, the refrigerant passage 500 penetrates the first compression unit 300 and the second compression unit 400 to form a closed space between the chamber 740 and the casing 100. A first flow path 510 for communicating; It is connected to the first flow path 510 and is formed in the intermediate bearing 350 located between the first compression unit 300 and the second compression unit 400, the chamber 740 and the first compression unit ( It is preferable to include a second flow path 520 for communicating the compression space 330 of the 300.

More specifically, the first flow path 510 vertically penetrates one side of the upper bearing 320, the first cylinder 310, the intermediate bearing 350, the second cylinder 410, and the lower bearing 450. Is formed.

The second flow path 520 communicates with a portion formed in the intermediate bearing 350 of the first flow path 510 and communicates with a first discharge chamber (not shown) in which the refrigerant of the first compression unit 300 is sucked.

The actuator 600 has a through flow path 611 through which the refrigerant on the first flow path 510 is communicated in the same direction as the first flow path, and has a stepped portion 612 at one end thereof, and the intermediate bearing 350. A valve body 610 inserted into the actuator insertion groove 351 formed in the valve body 610; A spring 620 coupled to the other end of the valve body 610; The electromagnet 630 is connected to the valve body 610 and moves the valve body 610 according to a control signal.

The through flow path 611 overlaps the first flow path 510 when the valve body 610 moves forward to allow the refrigerant to communicate with each other, and is disposed to be displaced from the first flow path 510 when the valve body 610 moves backward. The valve body 610 is formed at an appropriate position to close the first flow path.

The step portion 612 is in contact with the intermediate bearing 350 when the valve body 610 advances to serve as a stopper, so that the refrigerant can be communicated to the second flow path 520 when the valve body 610 is reversed. Is formed.

Referring to the operation and effects of the present invention the multi-stage rotary compressor as described above are as follows.

3 is a cross-sectional view showing the operation in the power mode according to an embodiment of the present invention.

As shown in the drawing, first, in the case of a power mode in which a required amount of refrigerant is large, the control valve 715 is opened to allow the refrigerant to flow into the first compression unit 300. In addition, the refrigerant is introduced into the second compression unit 400 through the second suction pipe 730.

When the power is applied to the drive unit 200, the rotating shaft 230 rotates and the first rolling piston 340 and the second rolling piston 440 is pivoting in the compression space (330, 430) of each cylinder A volume is formed between the first vane (not shown) and the second vane (not shown) to suck the refrigerant. Some of the refrigerant via the accumulator 130 is sucked into the first compression unit 300 through the first suction pipe 710, is compressed, and discharged into the casing 100 through the first discharge hole 360. The remaining refrigerant via the accumulator 130 is sucked into the second compression unit 400 through the second suction pipe 730 and is compressed to be discharged into the chamber 740 through the second discharge hole 460.

At this time, the electromagnet 630 of the actuator 600 is turned off and the valve body 610 is advanced by the elastic force of the spring 620 so that the through flow path 611 and the first flow path 510 overlap each other. In this case, the refrigerant is compressed and discharged from the second compression unit 400 and the refrigerant stored in the chamber 740 is discharged into the casing 100 through the first flow path 510. The refrigerant discharged from the first compression unit 300 and the second compression unit 400, respectively, saturates the inside of the casing 100 and repeats the process of being discharged to the outside of the casing 100 through the discharge tube.

As described above, in the power mode, the first and second compression units are connected in parallel, respectively, are compressed and discharged, are combined in the casing 100, and then moved to the outside of the compressor through the discharge pipe. Compared with the discharge amount of the refrigerant.

Figure 4 is a cross-sectional view showing the operation in the saving mode according to an embodiment of the present invention.

As shown in the drawing, the control valve 715 is operated to prevent the suction refrigerant passing through the accumulator 130 from entering the first compression unit 300. The refrigerant passing through the accumulator 130 is sucked and compressed into the second compression unit 400 through the second suction pipe 730 and then discharged into the chamber 740 through the second discharge hole 460.

At this time, the electromagnet 630 of the actuator 600 is turned on to reverse the valve body 610. In such a position, the valve body 610 blocks the first flow path 510 and simultaneously opens the second flow path 520, which is discharged after being compressed in the second compression unit 400 and stored in the chamber 740. The refrigerant flows into the compression space 330 of the first compression unit 300 through the second flow path 520 and is recompressed. The recompressed refrigerant is discharged into the casing 100 through the first discharge hole 360 and guided to the external refrigeration system through the discharge tube.

As such, in the saving mode, the refrigerant once compressed in the second compression unit 400 is moved back to the first compression unit 300 and recompressed. That is, since the compression units are connected in series and the refrigerant is discharged while passing through the second compression unit 400 and the first compression unit 300 sequentially, the discharge amount of the refrigerant is relatively small, but a high compression ratio can be obtained. In addition, in order to obtain an appropriate discharge pressure, a two-stage compression process is performed. In particular, in the case of the first compression unit 300, since the refrigerant compressed to some extent by the second compression unit 400 is sucked, the power consumption is particularly low. Holding Therefore, in the saving mode, the sum of the required powers of the first and second compression units is smaller than that in the power mode, thereby achieving a power saving effect.

In addition, the present invention has the effect of lowering the manufacturing cost because it is possible to realize the variable capacity by implementing the power mode and the saving mode by using a relatively low-cost constant speed motor without using an expensive inverter motor with a control unit.                     

Hereinafter, a second embodiment of the present invention will be described. Descriptions on the same items as in the first embodiment will be omitted.

5 is an enlarged cross-sectional view showing a second embodiment of the present invention.

As shown therein, the actuator 800 has a refrigerant passage 811 formed in a predetermined depth in a direction parallel to the second passage 520 and in the actuator insertion groove 351 formed in the intermediate bearing 350. An inserted valve body 810; A spring 820 coupled to the other end of the valve body 810; The electromagnet 830 is connected to the valve body 810 and moves the valve body 810 according to a control signal.

The valve body 810 has a body portion 812 formed smaller in diameter than the actuator insertion groove 351 formed in the intermediate bearing 350; An upper stepped part 813 connected to the body part 812 and formed to be stepped to close the first flow path 510 during the backward movement; A lower stepped part 814 connected to the body part 812 to close the second flow path 520 when moving forward, and formed to be shorter than the upper stepped part 813; And a connection hole 815 formed in the body portion 812 in a direction in which the lower step portion 814 is positioned and connected to the through flow path 811.

Hereinafter, the operation of the second embodiment of the present invention will be described.

6 is a cross-sectional view showing the operation in the power mode according to an embodiment of the present invention.

As shown in the drawing, the control valve 715 is opened in the same manner as the first embodiment to allow the refrigerant to flow into the first compression unit 300. In addition, the refrigerant is introduced into the second compression unit 400 through the second suction pipe 730. At this time, the electromagnet 830 of the actuator 800 is turned off and the valve body 810 is advanced by the elastic force of the spring 820. In this case, the refrigerant is compressed and discharged from the second compression unit 400 and the refrigerant stored in the chamber 740 is discharged into the casing 100 through the first flow path 510. At this time, since the body portion 812 of the valve body 810 is formed to have a smaller diameter than the actuator insertion groove 351, the refrigerant may flow through the first flow path 510. In addition, since the lower step part 814 blocks the second flow path 520 during the forward movement, all the refrigerant stored in the chamber 740 moves only through the first flow path 510. The refrigerant discharged from the first compression unit 300 and the second compression unit 400, respectively, saturates the inside of the casing 100 and repeats the process of being discharged to the outside of the casing 100 through the discharge tube.

7 is a cross-sectional view showing the operation in the saving mode according to an embodiment of the present invention.

As shown in the drawing, as in the first embodiment, the control valve 715 is operated to prevent the suction refrigerant passing through the accumulator 130 from entering the first compression unit 300. The refrigerant passing through the accumulator 130 is sucked and compressed into the second compression unit 400 through the second suction pipe 730 and then discharged into the chamber 740 through the second discharge hole 460.

At this time, the electromagnet 830 of the actuator 800 is turned on to reverse the valve body 810. In this position, the upper step part 813 closes the first flow path 510 and the second flow path 520 opens. That is, the refrigerant stored in the chamber 740 flows into the compression space 330 of the first compression unit 300 along the second flow path 520 through the connection hole 815 and the through flow path 811. Will be compressed. The recompressed refrigerant is discharged into the casing 100 through the first discharge hole and guided to the external refrigeration system through the discharge tube.

Hereinafter, a third embodiment of the present invention will be described. Descriptions on the same items as in the first embodiment will be omitted.

8 is an enlarged cross-sectional view showing a third embodiment of the present invention.

As shown in FIG. 2, the actuator 900 includes a through passage 911 formed through the second passage 520 in a direction parallel to the second passage 520, and has a stepped portion 912 at one end thereof. A valve body 910 inserted into the valve body; A spring 920 coupled to the other end of the valve body 910; It is configured to include an electromagnet 930 connected to the valve body 910 to move the valve body 910 according to a control signal.

The through passage 911 overlaps the second flow passage 520 when the valve body 910 moves forward to allow the refrigerant to communicate with each other, and is disposed to deviate from the second flow passage 520 when the valve body 910 moves backward. The valve body 910 is formed in a suitable position to close the second flow path.

The stepped part 912 closes the first flow path 510 when the valve body 910 moves forward, and is formed at a suitable position such that the stepped part 912 stays in the free space 352 formed in the intermediate bearing 350. do.

Hereinafter, the operation of the third embodiment of the present invention will be described.

9 is a cross-sectional view showing the operation in the power mode according to an embodiment of the present invention.

As shown in the drawing, the control valve 715 is opened in the same manner as the first embodiment to allow the refrigerant to flow into the first compression unit 300. In addition, the refrigerant is introduced into the second compression unit 400 through the second suction pipe 730. At this time, the electromagnet 930 of the actuator 900 is turned on to reverse the valve body 910. In this case, the refrigerant is compressed and discharged in the second compression unit 400, and the refrigerant stored in the chamber 740 is discharged into the casing 100 along the first flow path 510. That is, the refrigerant is moved through the first flow path 510 through the free space 352 formed in the intermediate bearing 350, but the valve body 910 closes the second flow path 520, the refrigerant is The two flow paths 520 may not move. The refrigerant discharged from the first compression unit 300 and the second compression unit 400, respectively, saturates the inside of the casing 100 and repeats the process of being discharged to the outside of the casing 100 through the discharge tube.

10 is a cross-sectional view showing the operation in the saving mode according to an embodiment of the present invention.

As shown in the drawing, as in the first embodiment, the control valve 715 is operated to prevent the suction refrigerant passing through the accumulator 130 from entering the first compression unit 300. The refrigerant passing through the accumulator 130 is sucked and compressed into the second compression unit 400 through the second suction pipe 730 and then discharged into the chamber 740 through the second discharge hole 460.

At this time, the electromagnet 730 of the actuator 700 is turned off to advance the valve body 910. In this position, the step portion 912 closes the first flow passage 510 and the second flow passage 520 coincides with the through flow passage 911 to open. That is, the refrigerant stored in the chamber 740 flows into the compression space 330 of the first compression unit 300 along the second flow path 520 through the through flow path 911 and is recompressed. The recompressed refrigerant is discharged into the casing 100 through the first discharge hole and guided to the external refrigeration system through the discharge tube.

The multi-stage rotary compressor of the present invention not only improves the efficiency of the compressor by using all the compression units in the saving mode, but also recompresses the refrigerant once compressed, thereby achieving a high discharge pressure, thereby improving volumetric efficiency.

In addition, by using the actuator, the power mode and the saving mode are realized by a relatively simple configuration, which eliminates the need for a piece for retracting and fixing the vanes, thereby eliminating problems such as wear and foreign matters, thereby improving reliability.

In addition, it is possible to reduce the manufacturing cost by varying the capacity while using a low-cost constant speed motor.

Claims (16)

delete delete A first compression unit and a second compression unit having different compression spaces are provided in the inner space of one casing, Each of the first compression unit and the second compression unit independently sucks and compresses the refrigerant according to an operation mode to discharge the refrigerant into the inner space of the casing, or the refrigerant compressed in the first stage by the second compression unit is 2 in the first compression unit. However, a valve is provided between the first compression unit and the second compression unit to switch the flow direction of the refrigerant to change the operation mode so as to be compressed and discharged into the inner space of the casing. The valve, A first valve installed at the suction side of the first compression unit to control the flow of the refrigerant, and a second valve installed between the discharge side of the second compression unit and the inner space of the casing to control the flow direction of the refrigerant; Multi-stage rotary compressor consisting of two valves. The method of claim 3, The first valve selectively opens and closes the suction side of the first compression unit according to the operation mode of the compressor. The second valve selectively selects a first flow path between the discharge side of the second compression unit and the inner space of the casing or a second flow path between the discharge side of the second compression unit and the inlet of the first compression unit according to the operation mode of the compressor. Multistage rotary compressors. The method of claim 4, wherein And a chamber for separating the discharge side of the second compression unit from the inner space of the casing and accommodating the inlet end of the first flow path and the second flow path on the discharge side of the second compression unit. One casing having a closed inner space; A first compression unit installed in the inner space of the casing to form a first compression space; And And a second compression unit which is separated from the first compression unit and installed in the inner space of the casing and forms a second compression space. On the suction side of the first compression unit is provided a first valve which is opened in the power operation mode, but closed in the saving operation mode, The discharge side of the second compression unit communicates the discharge side of the second compression unit with the inner space of the casing in the power operation mode, while the discharge side of the second compression unit communicates with the suction side of the first compression unit in the saving operation mode. A multistage rotary compressor provided with a second valve. The method of claim 6, And a first suction pipe and a second suction pipe are respectively connected to the suction side of the first compression unit and the second compression unit, and the first valve is installed in the middle of the first suction pipe. The method of claim 6, The first compression unit and the second compression unit have a first flow path for guiding the refrigerant discharged from the second compression unit to the inner space of the casing and a second flow path for guiding the suction side of the first compression unit, respectively. And a second valve disposed between the first flow path and the second flow path so that the first flow path and the second flow path are selectively opened and closed by the second valve. The method of claim 8, The second valve is provided with an electromagnet, the multi-stage rotary compressor capable of forcibly opening and closing the first flow path and the second flow path while the valve body is moved by the power applied to the electromagnet. 10. The method of claim 9, The valve body of the second valve is a multi-stage rotary compressor having a first communication portion is formed to communicate the first flow path in the power operation mode, the second communication portion is formed to communicate the second flow path in the saving operation mode. 10. The method of claim 9, And a chamber coupled to the second compression unit to receive the discharge side of the second compression unit, the first flow path and the second flow path, and to separate the internal space of the casing. 10. The method of claim 9, The first compression unit and the second compression unit are separated by a bearing member having the second flow path, and the valve body of the second valve moves in a radial direction to selectively open and close the first flow path and the second flow path. Multistage rotary compressor. The method of claim 12, Electromagnet of the second valve is a multi-stage rotary compressor is fixed to the outer peripheral surface of the casing in the outer casing. 10. The method of claim 9, The first compression unit and the second compression unit are separated by a bearing member having the second flow path, and the valve body of the second valve moves in the axial direction to selectively open and close the first flow path and the second flow path. Multistage rotary compressor. The method of claim 14, A chamber is coupled to the second compression unit to receive the discharge side of the second compression unit, the first flow path and the second flow path to be separated from the inner space of the casing. The electromagnet of the second valve is a multi-stage rotary compressor is fixed to the outer peripheral surface of the chamber inside the casing. The method according to any one of claims 3 to 15, Multi-stage rotary compressor is installed in the inner space of the casing one drive motor to rotate at constant speed.

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