JP2013029059A - Rotary two stage compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary two stage compressor capable of suppressing pressure pulsation in an intermediate flow path by improving followability of a refrigerant introduced into a high stage compression part, and capable of preventing a drop of operation efficiency during low load operation.SOLUTION: A two stage compressor 100 as the rotary two-stage compressor of internal high-pressure type includes a low stage cover 19 that covers a low stage outlet port 16 and forms a low stage discharge space 20 therein. Further, in the two stage compressor 100, an intermediate passage 51 that connects the low stage discharge space 20 and the high stage compression chamber 35 are formed in a compression mechanism 3. Further, the two-stage compressor 100 includes a bypass mechanism (bypass port 23, a bypass valve 24, and a bypass valve guard 25) in the low stage cover 19, which opens when a load is smaller than a predetermined load and which connects the low stage discharge space 20 and a discharge pressure space 53.

Description

  The present invention relates to a rotary two-stage compressor having two compression sections.

  Conventionally, there is a rotary two-stage compressor in which two compression sections (a low-stage compression section and a high-stage compression section) are provided in the compression mechanism section, and these low-stage compression section and high-stage compression section are connected in series. In such a rotary two-stage compressor, the low-stage compressor compresses the refrigerant sucked from the heat pump cycle up to a predetermined pressure (attainment pressure). This ultimate pressure is determined by setting the compression chamber volume of the low-stage compression unit and the compression chamber volume of the high-stage compression unit. The high stage compression unit further compresses the refrigerant compressed by the low stage compression unit. In the case of an internal high-pressure rotary two-stage compressor, the refrigerant compressed in the high-stage compression unit is discharged from the high-stage compression unit to the internal space of the sealed container and is discharged from the internal space of the closed container to the heat pump cycle. The

  Conventionally, in an internal high-pressure rotary two-stage compressor, an intermediate flow path for introducing an intermediate-pressure refrigerant compressed in a low-stage compression section into the high-stage compression section is formed so as to pass outside the sealed container. It was.

  However, in the conventional rotary two-stage compressor in which the intermediate flow path is formed so as to pass outside the sealed container, the intermediate communication flow path becomes extremely long. As a result, the followability when the refrigerant in the intermediate flow path is introduced into the high-stage compression section is deteriorated, causing pressure pulsation in the intermediate flow path, and the effect of suppressing sufficient pressure pulsation cannot be obtained. was there.

Thus, a conventional internal high-pressure rotary two-stage compressor has been proposed in which an intermediate flow path is formed inside a sealed container.
As such a conventional rotary two-stage compressor, a discharge space that constitutes an intermediate flow path is formed in an intermediate partition plate that partitions a low-stage compression section and a high-stage compression section, and an intermediate pressure refrigerant ( A refrigerant that discharges the refrigerant (from the low-stage compression section) and prevents the intermediate-pressure refrigerant from excessively flowing out to the high-stage compression section has been proposed (see, for example, Patent Document 1).
Also, in such a conventional rotary two-stage compressor, the intermediate flow path is provided in the compression mechanism section by shifting the phase of the suction port of the high-stage compression unit from the phase of the suction port of the low-stage compression unit. Has also been proposed (see, for example, Patent Document 2).
In addition, as such a conventional rotary two-stage compressor, an intermediate flow path is disposed between the vane groove and the low-stage and high-stage intake flow paths, and the intermediate flow path is provided through the compression mechanism section. Has also been proposed (see, for example, Patent Document 3).

JP 2000-87892 A JP 2007-113542 A JP 2010-156226 A

  In a heat pump device (heat pump cycle) using a compressor, the pressure of the refrigerant discharged from the compressor (in other words, the pressure of the refrigerant flowing into the condenser) may be low, such as when the load is small. However, since the conventional rotary two-stage compressor (for example, see Patent Documents 1 to 3) in which the intermediate flow path is formed in the compression mechanism section does not consider such low load operation, the rotary two-stage compressor In some cases, the pressure of the refrigerant discharged from the compressor becomes higher than a desired pressure, resulting in an overcompressed state. For this reason, the conventional rotary two-stage compressor in which the intermediate flow path is formed in the compression mechanism section has a problem that the operation efficiency at the time of low load operation is lowered.

  Moreover, since the rotary two-stage compressor described in Patent Document 1 forms a discharge space in which the intermediate pressure refrigerant is discharged in the intermediate partition plate, the distance between the bearings of the compression mechanism (the upper and lower ends of the compression mechanism are provided). , The distance between the bearings that rotatably support the drive shaft is increased. For this reason, the rotary two-stage compressor described in Patent Document 1 has a problem in that the drive shaft bends when a refrigerant load is applied to the compression chamber, and the reliability of the bearing is lowered.

  In the rotary two-stage compressor described in Patent Document 2, the phase of the suction port of the high-stage compression unit is shifted from the phase of the suction port of the low-stage compression unit. There was also a problem that the volume increased and the compression efficiency was lowered.

  Further, in the rotary two-stage compressor described in Patent Document 3, since the installation area of the intermediate flow path is narrow, the flow area of the intermediate flow path is restricted, and the efficiency is reduced due to pressure loss. There was also.

  The present invention has been made to solve at least one of the above-described problems, and can improve the followability of the refrigerant introduced into the high-stage compression section and suppress pressure pulsation in the intermediate flow path. An object of the present invention is to obtain a rotary two-stage compressor that can prevent a decrease in operating efficiency during low-load operation.

A rotary two-stage compressor according to the present invention includes a hermetic container, a compression mechanism unit disposed inside the hermetic container, an electric motor disposed inside the hermetic container and serving as a drive source for the compression mechanism unit, A drive shaft that transmits the driving force of the electric motor to the compression mechanism, and the compression mechanism is formed with a low-stage frame and a first through-hole serving as a low-stage compression chamber. A low-stage cylinder in which one opening of the first through-hole is closed, an intermediate partition plate that closes the other opening of the first through-hole, and a second through-hole serving as a high-stage compression chamber are formed. A high stage cylinder in which one opening of the second through hole is closed by the intermediate partition plate, a high stage frame closing the other opening of the second through hole, and an eccentric part of the drive shaft. A low-stage row provided for eccentric rotational movement inside the low-stage compression chamber A low-pressure piston that is provided at an eccentric portion of the drive shaft and that eccentrically rotates inside the high-stage compression chamber; and a low-pressure that partitions the inside of the low-stage compression chamber into a suction space and a compression space A vane and a high-pressure vane that divides the inside of the high-stage compression chamber into a suction space and a compression space, and a low-stage frame, a low-stage cylinder, an intermediate partition plate, a high-stage cylinder, and a high-stage frame are sequentially stacked. The low-stage compression section and the high-stage compression section are formed, and the refrigerant sucked from the pipe connected to the low-pressure suction port of the low-stage compression section is compressed in the low-stage compression chamber, and the refrigerant A rotary two-stage compressor that introduces the refrigerant into the high-stage compression chamber via an intermediate flow path and compresses the refrigerant again, and discharges the refrigerant compressed in the high-stage compression chamber into a discharge pressure space that is an internal space of the sealed container Because
A low-stage discharge port for discharging the refrigerant compressed in the low-stage compression chamber is formed in the low-stage frame, and includes a low-stage cover that covers the low-stage discharge port and forms a low-stage discharge space therein, The intermediate flow path is formed through the low-stage frame, the low-stage cylinder, and the intermediate partition plate, and communicates the low-stage discharge space and the high-stage compression chamber to the low-stage cover. Is provided with a bypass mechanism that opens when the load is smaller than a predetermined load and communicates the low-stage discharge space and the discharge pressure space.

  In the rotary two-stage compressor according to the present invention, since the intermediate flow path is formed in the compression mechanism without being formed outside the sealed container, the intermediate flow path can be formed short. For this reason, the followability of the refrigerant introduced into the high-stage compression section can be improved, and pressure pulsation in the intermediate flow path can be suppressed.

  The rotary two-stage compressor according to the present invention includes a bypass mechanism that opens when the load is smaller than a predetermined load and communicates the low-stage discharge space and the discharge pressure space. For this reason, at the time of low load operation, the refrigerant compressed by the low stage compression unit can be bypassed and discharged to the heat pump cycle without being compressed by the high stage compression unit. Therefore, the rotary two-stage compressor according to the present invention can reduce an overcompression loss that occurs during low-load operation, and can prevent a reduction in operating efficiency during low-load operation.

It is a longitudinal section showing a two-stage compressor concerning an embodiment of the invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is DD sectional drawing of FIG. It is EE sectional drawing of FIG. It is the figure which compared the operating efficiency of the two-stage compressor which concerns on this Embodiment, and the conventional rotary two-stage compressor.

Embodiment.
Hereinafter, the configuration of an example of the rotary two-stage compressor (two-stage compressor 100) according to the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing a two-stage compressor according to an embodiment of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 1, FIG. 3 is a cross-sectional view taken along the line BB in FIG. 1, FIG. 4 is a cross-sectional view taken along the line CC in FIG. DD sectional drawing is shown, FIG. 6 shows EE sectional drawing of FIG. FIG. 1 is a diagram in which longitudinal sections cut at a plurality of cutting positions are combined to facilitate understanding of the configuration of the two-stage compressor 100. Therefore, the exact position of each component in plan view or bottom view is the position shown in FIGS.

  A two-stage compressor 100 according to the present embodiment includes two compression units (a low-stage compression unit 10 and a high-stage compression unit 30) in the compression mechanism unit 3. The two-stage compressor 100 includes an electric motor 2 (motor section), a low-stage compression section 10, a high-stage compression section 30, a low-stage cover 19, a high-stage cover 39, a low-stage frame 14, a high-stage frame 34, and an intermediate partition plate. 50, the drive shaft 4 and the like. More specifically, inside the sealed container 1 from the lower part to the upper part, the high stage cover 39, the high stage frame 34, the high stage compression part 30, the intermediate partition plate 50, the low stage compression part 10, the low stage frame 14, low The step cover 19 and the electric motor 2 are arranged in this order. Moreover, the drive shaft 4 is provided along the up-down direction of the airtight container 1, and the lubricating oil storage part 6 which stores the lubricating oil 6a in the lower part (namely, lower end part of the drive shaft 4) of the airtight container 1 is provided. Is formed. This lubricating oil 6a lubricates the compression mechanism 3 and the bearing.

  The low-stage compression unit 10 of the compression mechanism unit 3 includes a low-stage cylinder 11, a low-stage rolling piston 12, a low-stage vane 26 (see FIG. 4), and the like. The low-stage cylinder 11 has a substantially flat plate shape, and a substantially cylindrical through hole serving as the low-stage compression chamber 15 is formed in a substantially central part. The through hole has an upper opening closed by the low-stage frame 14 and a lower opening closed by the intermediate partition plate 50 to form a low-stage compression chamber 15. The low-stage compression chamber 15 communicates with a low-stage suction port 21 and a low-stage discharge port 16 formed in the low-stage frame 14. The low-stage suction port 21 is connected to the suction pipe 8 via a connecting pipe 9 and a suction muffler 7 provided outside the sealed container 1. That is, the low stage suction port 21 is connected to the low pressure side of the heat pump cycle. The low-stage discharge port 16 is provided with a reed valve in which a plate-like low-stage discharge valve 17 and a low-stage valve presser 18 are attached by rivets 18a (see FIG. 3). By pushing up the low-stage discharge valve 17 of the reed valve and opening the low-stage discharge port 16, the low-stage compression chamber 15 communicates with a low-stage discharge space 20 described later.

  The low-stage compression chamber 15 is provided with a low-stage rolling piston 12 and a low-stage vane 26. The low-stage rolling piston 12 has a substantially cylindrical shape and is provided at the eccentric portion of the drive shaft 4. The low stage vane 26 is slidably provided in a low stage vane groove 27 formed in the low stage cylinder 11. Further, the low stage vane 26 is biased in the direction of the drive shaft 4 by a biasing member such as a spring, and the tip part thereof can follow the outer peripheral part of the low stage rolling piston 12. Thus, the low-stage compression chamber 15 is partitioned into a suction space that communicates with the low-stage suction port 21 and a compression space that communicates with the low-stage discharge port 16. As can be seen from FIGS. 3 and 4, the low-stage suction port 21 of the low-stage compression chamber 15 communicates with the low-stage compression chamber 15 in the vicinity of the left side of the low-stage vane 26 in plan view. Further, the low stage discharge port 16 communicates with the low stage compression chamber 15 in the vicinity of the right side of the low stage vane 26 in a plan view.

  The high stage compression unit 30 includes a high stage cylinder 31, a high stage rolling piston 32, a high stage vane 42 (see FIG. 5), and the like. The high-stage cylinder 31 has a substantially flat plate shape, and a substantially cylindrical through hole serving as the high-stage compression chamber 35 is formed in a substantially central part. The through hole has an upper opening closed by an intermediate partition plate 50 and a lower opening closed by a high frame 34 to form a high compression chamber 35. The high-stage compression chamber 35 is formed to have a smaller volume than the low-stage compression chamber 15. The high-stage compression chamber 35 communicates with a high-stage suction port 41 formed in the high-stage cylinder 31 and a high-stage discharge port 36 formed in the high-stage frame 34. The high-stage suction port 41 of the high-stage compression unit 30 can communicate with the low-stage discharge port 16 of the low-stage compression unit 10 via a low-stage discharge space 20 and an intermediate flow path 51 described later. The high-stage discharge port 36 is provided with a reed valve in which a plate-like high-stage discharge valve 37 and a high-stage valve presser 38 are attached by rivets 38a (see FIG. 6). By pushing up the high-stage discharge valve 37 of the reed valve to open the high-stage discharge port 36, the high-stage compression chamber 35 communicates with a high-stage discharge space 40 described later.

  The high stage compression chamber 35 is provided with a high stage rolling piston 32 and a high stage vane 42. The high-stage rolling piston 32 has a substantially cylindrical shape and is provided at the eccentric portion of the drive shaft 4. In the present embodiment, the high-stage rolling piston 32 has a phase substantially opposite to that of the low-stage rolling piston 12 (a position rotated about 180 ° about the rotation axis of the drive shaft 4) in plan view. The high stage vane 42 is slidably provided in a high stage vane groove 43 formed in the high stage cylinder 31. Further, the high stage vane 42 is biased in the direction of the drive shaft 4 by a biasing member such as a spring, and the tip part thereof can follow the outer peripheral part of the high stage rolling piston 32. Thereby, the high-stage compression chamber 35 is partitioned into a suction space in which the high-stage suction port 41 communicates and a compression space in which the high-stage discharge port 36 communicates. As can be seen from FIGS. 5 and 6, the high stage suction port 41 communicates with the high stage compression chamber 35 in the vicinity of the left side of the high stage vane 42 in plan view. The high stage discharge port 36 communicates with the high stage compression chamber 35 in the vicinity of the right side of the high stage vane 42 in plan view.

  As can be seen from FIGS. 3 to 6, the low-stage suction port 21 of the low-stage compression chamber 15 and the high-stage suction port 41 of the high-stage compression chamber 35 have substantially the same phase in plan view. The low stage discharge port 16 and the high stage discharge port 36 have substantially the same phase in plan view. For this reason, unlike the rotary two-stage compressor shown in Patent Document 2, the two-stage compressor 100 according to the present embodiment does not increase the dead volume of the high-stage compression chamber 35 and may reduce the compression efficiency. Absent.

  The low-stage frame 14 includes an upper bearing portion and rotatably supports a substantially intermediate portion of the drive shaft 4. As described above, the low-stage discharge port 16 of the low-stage compression unit 10 is formed in the low-stage frame 14. The low-stage cover 19 is a cup-shaped container having an open bottom. The low stage cover 19 is provided so as to cover the low stage discharge port 16 from above, and a low stage discharge space 20 is formed therein.

  Further, an intermediate flow path 51 is also communicated with the low stage discharge space 20. The intermediate flow path 51 penetrates the low-stage frame 14, the low-stage cylinder 11, and the intermediate partition plate 50 in the vertical direction, and communicates the low-stage discharge space 20 and the high-stage suction port 41. That is, the refrigerant flowing into the low stage discharge space 20 is sucked into the high stage compression unit 30 through the intermediate partition plate 50.

  In plan view, the intermediate flow path 51 is on the left side of the low-stage vane 26 when passing through the low-stage cylinder 11 and is lower than the low-stage intake port 21 (that is, the low-stage vane groove). It penetrates a position away from 27). In other words, when the rotation direction on the side closer to the distance from the low stage vane 26 to the low stage suction port 21 is set as the positive direction with respect to the central axis of the drive shaft 4 (the arrow direction shown in FIG. 4), the intermediate flow path 51 is formed downstream of the low-stage inlet 21 in the positive direction.

  The high stage frame 34 includes a lower bearing portion and rotatably supports the lower end portion of the drive shaft 4. As described above, the high stage discharge port 36 of the high stage compression unit 30 is formed in the high stage frame 34. The high stage cover 39 is a cup-shaped container having an upper opening. The high stage cover 39 is provided so as to cover the high stage discharge port 36 from below, and a high stage discharge space 40 is formed therein.

  Further, a discharge flow path 52 communicating with the internal space of the sealed container 1 is formed in the high-stage discharge space 40. The discharge passage 52 penetrates the high stage frame 34, the high stage cylinder 31, the intermediate partition plate 50, the low stage cylinder 11, and the low stage frame 14 in the vertical direction, and the high stage discharge space 40 and the internal space of the sealed container 1. And communicate with. That is, in the two-stage compressor 100 according to the present embodiment, the internal high pressure in which the sealed container 1 becomes the discharge pressure space 53 (the space that becomes the pressure of the high-pressure refrigerant discharged from the high-stage compressor 30 during steady operation). The type of compressor. For example, a discharge pipe 5 is provided in the upper part of the sealed container 1, and the high-pressure refrigerant discharged to the sealed container 1 is discharged from the discharge pipe 5 to the outside. In a plan view, the discharge flow path 52 penetrates the intermediate flow path 51 at a point-symmetrical position with respect to the central axis of the drive shaft 4.

  The electric motor 2 serves as a drive source for the low-stage compression unit 10 and the high-stage compression unit 30. The electric motor 2 includes a stator 2a and a rotor 2b. The stator 2 a has a substantially cylindrical shape and is fixed to the inner peripheral portion of the sealed container 1. The rotor 2b has a substantially cylindrical shape, and is disposed on the inner peripheral portion of the stator 2a with a predetermined gap therebetween. Further, the upper end portion of the drive shaft 4 is fitted into the inner peripheral portion of the rotor 2b.

  Further, in the two-stage compressor 100 according to the present embodiment, the injector 60 is provided in the low-stage cover 19. One end of the injector 60 opens into the low-stage discharge space 20, and an injection pipe 61 is connected to the other end. The injector 60 is for injecting the refrigerant in the heat pump cycle other than the two-stage compressor 100 into the refrigerant discharged from the low-stage compressor 10. For this reason, the connection position of the injector 60 is not limited to the low-stage cover 19, and the flow path (low-stage discharge) until the refrigerant discharged from the low-stage compression unit 10 is sucked into the high-stage compression unit 30. (Space), it is possible to connect to an arbitrary position.

Further, in the two-stage compressor 100 according to the present embodiment, the low-stage cover 19 is formed with a bypass port 23 that communicates the low-stage discharge space 20 and the discharge pressure space 53 that is the internal space of the sealed container 1. Yes. The bypass port 23 is provided with a reed valve in which a plate-like bypass valve 24 and a bypass valve presser 25 are attached by a rivet 29 (see FIG. 2). These are called bypass mechanisms.
In the present embodiment, the positional relationship between the bypass port 23 and the intermediate flow path 51 is as shown in FIG. That is, when the rotation direction on the side closer to the distance from the low-stage discharge port 16 to the bypass port 23 is the positive direction with reference to the central axis of the drive shaft 4 (the arrow direction shown in FIG. 2), the intermediate flow path 51 is In the positive direction, it is formed downstream of the bypass port 23.

Next, the operation of the two-stage compressor 100 will be described.
When electric power is supplied, the electric motor 2 operates. The electric motor 2 and the compression mechanism unit 3 are connected by a drive shaft 4, and power generated by the electric motor 2 is transmitted to the compression mechanism unit 3 through the drive shaft 4. Specifically, when supplied with electric power, the rotor 2b of the electric motor 2 rotates. When the rotor 2b rotates, the drive shaft 4 inserted into the rotor 2b also rotates. When the drive shaft 4 rotates, the low-stage rolling piston 12 and the high-stage rolling piston 32 into which the drive shaft 4 is inserted are eccentrically rotated inside the low-stage compression chamber 15 and the high-stage compression chamber 35, respectively. As the low stage rolling piston 12 and the high stage rolling piston 32 rotate eccentrically, the refrigerant is compressed by the low stage compression unit 10 and the high stage compression unit 30.

In the two-stage compressor 100 operating in this way, the refrigerant flows as follows.
First, low-pressure refrigerant flows into the suction muffler 7 from the outside through the suction pipe 8. The low-pressure refrigerant flowing into the suction muffler 7 is sucked into the low-stage compression chamber 15 through the connecting pipe 9. The low-pressure refrigerant sucked into the low stage compression chamber 15 is compressed to an intermediate pressure in the low stage compression chamber 15. When the refrigerant is compressed to an intermediate pressure, the low stage discharge valve 17 is opened due to the pressure difference between the refrigerant in the low stage compression chamber 15 and the refrigerant in the low stage discharge space 20, and the refrigerant in the low stage compression chamber 15 is low. The liquid is discharged from the stage discharge port 16 to the low stage discharge space 20. Here, the intermediate pressure is a pressure determined from the ratio between the volume of the suction chamber of the low-stage compression chamber 15 and the volume of the suction chamber of the high-stage compression chamber 35.

  The intermediate pressure refrigerant discharged to the low stage discharge space 20 is sucked into the high stage compression chamber 35 through the intermediate flow path 51. The intermediate-pressure refrigerant sucked into the high-stage compression chamber 35 is compressed to the discharge pressure in the high-stage compression chamber 35. When the refrigerant is compressed to the discharge pressure, the high stage discharge valve 37 is opened due to the pressure difference between the refrigerant in the high stage compression chamber 35 and the refrigerant in the high stage discharge space 40, and the refrigerant in the high stage compression chamber 35 becomes high. It is discharged from the stage discharge port 36 to the high stage discharge space 40. The refrigerant having the discharge pressure discharged to the high stage discharge space 40 is discharged to the discharge pressure space 53 above the low stage compression unit 10 via the discharge flow path 52. The refrigerant having the discharge pressure discharged into the discharge pressure space 53 is discharged from the discharge pipe 5 to the outside.

  In addition, when the injection operation is performed in the heat pump apparatus (heat pump cycle using the two-stage compressor 100) provided with the two-stage compressor 100, the injection refrigerant is passed through the injector 60 from the injection pipe 61 shown in FIG. Is injected into the low-stage discharge space 20. The injection refrigerant is mixed with the intermediate-pressure refrigerant discharged from the low-stage compression chamber 15 in the low-stage discharge space 20 and compressed by the high-stage compression unit 30.

  When the load of the heat pump device is small (hereinafter also referred to as low load operation), overcompression that results in discharge pressure (in other words, pressure of refrigerant flowing into the condenser) only by compression by the low-stage compression unit 10. It may be in a state. That is, the intermediate pressure of the refrigerant described above may be higher than the required discharge pressure. In such a case, in the two-stage compressor 100 according to the present embodiment, the bypass valve 24 is opened by the pressure difference between the refrigerant in the low-stage discharge space 20 and the refrigerant in the discharge pressure space 53, and the refrigerant in the low-stage discharge space 20. Is discharged from the bypass port 23 to the discharge pressure space 53. In other words, in the two-stage compressor 100 according to the present embodiment, when the pressure in the low-stage discharge space 20 becomes larger than the pressure in the discharge pressure space 53 by a predetermined value or more, the bypass valve 24 is deformed and the bypass port 23 is opened. That is, the refrigerant discharged from the low stage compression unit 10 to the low stage discharge space 20 is bypassed and discharged to the discharge pressure space 53 without being compressed by the high stage compression unit 30.

  In the overcompressed state, only the compression by the low-stage compression unit 10 results in the discharge pressure. Therefore, the compression by the high-stage compression unit 30 is useless, and if the high-stage compression unit 30 performs compression, the efficiency deteriorates. However, in the two-stage compressor 100, the refrigerant compressed by the low-stage compression unit 10 is discharged by bypassing the high-stage compression unit 30 when the over-compression state occurs. Therefore, loss (overcompression loss) when an overcompressed state occurs can be suppressed, and operation efficiency during low-load operation can be improved.

  In particular, in the two-stage compressor 100 according to the present embodiment, the bypass port 23 is formed in the low-stage cover 19. For this reason, the refrigerant discharged from the bypass port 23 to the discharge pressure space 53 is discharged to the discharge pressure space 53 in the sealed container 1 without passing through the intermediate flow path 51. That is, the refrigerant discharged from the bypass port 23 to the discharge pressure space 53 is discharged from the bypass port 23 to the discharge pressure space 53 without causing a compression loss due to passing through the intermediate flow path 51. Therefore, over-compression loss can be effectively suppressed during low-load operation.

  In addition, as mentioned above, the lower side of the airtight container 1 forms the lubricating oil storage part 6, and the lubricating oil 6a is enclosed. Since the lubricating oil 6a is supplied to the mechanical portion of the compression mechanism unit 3, an amount of at least the compression unit disposed in the upper side (the low-stage compression unit 10 in FIG. 1) is enclosed. In a general rotary two-stage compressor (see Patent Documents 1 to 3), when a rotary two-stage compressor is installed vertically, a low-stage compression section is provided below the high-stage compression section. For this reason, the rotary two-stage compressor which discharges the refrigerant | coolant compressed by the low stage compression part in the low stage cover (low stage discharge space) like the rotary two stage compressor described in patent document 2 and patent document 3 In this case, the low stage discharge space is provided below the low stage compression section. That is, the low stage cover is provided below the low stage compression section. Therefore, the low stage cover is immersed in the lubricating oil. In this case, if the bypass port 23 according to the present embodiment is to be formed in the low-stage cover, the lubricating oil enters the low-stage discharge space from the bypass port 23. Moreover, when discharging a refrigerant | coolant from the bypass port 23, lubricating oil is wound up and the outflow of lubricating oil from a rotary two-stage compressor is increased. For this reason, in a general rotary two-stage compressor, the bypass port 23 according to the present embodiment cannot be formed in the low-stage cover. Therefore, in the rotary two-stage compressor described in Patent Document 2 and Patent Document 3, when the rotary two-stage compressor is installed vertically, a bypass port is provided in a narrow and narrow flow path connecting the low-stage discharge space and the high-stage compression section. 23 can only be provided.

  However, when the two-stage compressor 100 according to the present embodiment is installed vertically, the low-stage compressor 10 is provided on the upper side of the high-stage compressor 30, contrary to the normal case. For this reason, the low stage discharge space 20 is provided above the low stage compression part 10, and the low stage cover 19 can be made the height which is not immersed in the lubricating oil 6a. As a result, the bypass port 23 can be provided in the low stage cover 19.

  Moreover, since the two-stage compressor 100 according to the present embodiment is provided with the bypass port 23 in the low-stage cover 19 instead of the intermediate flow path 51, the bypass valve 24 can be a reed valve having a simple structure. For this reason, the bypass valve 24 and the bypass valve presser 25 can be made the same components as the low stage discharge valve 17 and the low stage valve presser 18, the high stage discharge valve 37 and the high stage valve presser 38. Costs can be kept low by sharing parts. Further, since the structure of the bypass valve 24 is simplified, the cost for assembly can be reduced.

  Next, features of the intermediate flow path 51 of the two-stage compressor 100 according to the present embodiment will be described.

  As described above, the intermediate flow path 51 penetrates the low-stage frame 14, the low-stage cylinder 11, and the intermediate partition plate 50 in the vertical direction, and communicates the low-stage discharge space 20 and the high-stage suction port 41. That is, the refrigerant compressed by the low stage compression unit 10 flows into the intermediate flow path 51 after being discharged into the low stage discharge space 20. For this reason, unlike the rotary two-stage compressor described in Patent Document 1, it is not necessary to form the discharge space of the low-stage compression unit 10 in the intermediate partition plate 50. For this reason, unlike the rotary two-stage compressor described in Patent Document 1, the two-stage compressor 100 according to the present embodiment includes a low-stage frame 14 and a high-stage frame 34 that also function as a bearing portion of the drive shaft 4. The distance can be reduced, and the reliability of the two-stage compressor 100 (more specifically, the low-stage frame 14 and the high-stage frame 34 that also function as a bearing portion of the drive shaft 4) can be improved.

  Further, the intermediate flow path 51 is located farther from the lower stage vane 26 (in other words, the lower stage vane groove 27) than the lower stage inlet 21, that is, the lower stage inlet 21 and the lower stage vane 26 (in other words, It is formed at a position not between the low-stage vane groove 27). For this reason, unlike the intermediate flow path described in Patent Document 3, the intermediate flow path 51 according to the present embodiment can ensure a large flow path area, and can eliminate the cause of efficiency reduction due to pressure loss. Further, since the intermediate flow path 51 does not interfere with the low-stage suction port 21 and the low-stage vane 26 (in other words, the low-stage vane groove 27), the degree of freedom of installation of the flow path is increased. 4 and the like, the intermediate flow path 51 whose opening is substantially circular is shown, but any shape may be used as long as the opening is formed larger than the area of the low-stage discharge port 16.

  Pressure pulsation is generated in the intermediate flow path due to the amount of refrigerant flowing in and the density of the density. In particular, in an inverter-controlled rotary two-stage compressor, pressure pulsation is likely to occur because the rotational speed increases or decreases. In the conventional rotary two-stage compressor in which the intermediate flow path is arranged outside the sealed container, the followability of the refrigerant introduced into the high-stage compression section is poor, so that the pressure pulsation in the intermediate flow path is dissipated by resonance. In order to achieve this, it is necessary to set up various kinds of intermediate flow passages having flow passage pipe lengths. However, since the two-stage compressor 100 according to the present embodiment shortens the flow path length by providing the intermediate flow path 51 in the compression mechanism section 3, the low-stage compression section 10 to the high-stage compression section 30. Since the followability of the refrigerant introduced into the tank is improved and the pressure pulsation can be suppressed, the operation efficiency can be improved.

  As described above, when the rotation direction on the side closer to the distance from the low-stage discharge port 16 to the bypass port 23 is set to the positive direction with reference to the central axis of the drive shaft 4 (the arrow direction shown in FIG. 2), the intermediate flow The path 51 is formed downstream of the bypass port 23 in the positive direction. This positive direction is the main flow direction of the refrigerant flowing from the low stage discharge port 16 to the bypass port 23. By arranging the bypass port 23 and the intermediate flow path 51 in such a positional relationship, the refrigerant in an overcompressed state discharged from the low-stage compression unit 10 is bypassed (bypass mechanism 23, bypass valve 24 and bypass valve presser). 25), the air is discharged from the bypass port 23 into the sealed container 1 before reaching the intermediate flow path 51. For this reason, the refrigerant discharged to the discharge pressure space 53 is more reliably discharged to the discharge pressure space 53 without passing through the intermediate flow path 51, and the effect of the bypass mechanism is increased. On the other hand, even if the bypass mechanism (bypass mechanism provided in the low pressure cover) according to the present invention is provided in the conventional rotary two-stage compressor in which the intermediate channel is arranged outside the sealed container 1, the channel length of the intermediate channel is not increased. Since it becomes long, the refrigerant in the overcompressed state cannot be completely discharged from the bypass port 23, and a part of the refrigerant in the overcompressed state flows into the high-stage compression unit to cause useless compression, so that the efficiency is deteriorated.

  Finally, the improvement effect of the operation efficiency of the two-stage compressor 100 according to the present embodiment will be described.

  FIG. 7 is a diagram comparing the operational efficiencies of the two-stage compressor according to the present embodiment and the conventional rotary two-stage compressor. Note that the conventional rotary two-stage compressor shown in FIG. 7 is an internal high-pressure rotary two-stage compressor in which an intermediate flow path is disposed outside a sealed container, and includes a bypass mechanism as in the present embodiment. It has not been. FIG. 7 shows the operation efficiency of the two-stage compressor 100 according to the present embodiment with the operation efficiency of the conventional rotary two-stage compressor as a reference (100%).

  Comparing the operation efficiency at the time of steady operation (rated conditions shown in FIG. 7), the operation efficiency of the two-stage compressor 100 according to the present embodiment is about 102%, which is about 2 than the conventional rotary two-stage compressor. % Operating efficiency is improved. From this result, by forming the intermediate flow path 51 in the compression mechanism section 3, the followability of the refrigerant introduced into the high-stage compression section 30 can be improved, and pressure pulsations in the intermediate flow path can be suppressed, and the operating efficiency can be reduced. It can be seen that can be improved.

  Comparing the operation efficiency at the time of low load operation (low load condition shown in FIG. 7), the operation efficiency of the two-stage compressor 100 according to the present embodiment is about 101.5%, which is a conventional rotary two-stage compressor. The operating efficiency is improved by about 1/5%. From this result, the two-stage compressor 100 according to the present embodiment is in an overcompressed state by providing the low-stage cover 19 with a bypass mechanism (bypass port 23, bypass valve 24 and bypass valve presser 25). In addition, it is understood that the refrigerant compressed by the low-stage compression unit 10 can be discharged by bypassing the high-stage compression unit 30, and the operation efficiency can be improved.

  In the two-stage compressor 100 in which the intermediate flow path 51 is formed in the compression mechanism section 3, since the member that becomes the intermediate flow path does not protrude from the sealed container 1, it is possible to reduce the size, ease of packaging and transportation, and disassembly. Effects such as ease can also be obtained.

  DESCRIPTION OF SYMBOLS 1 Airtight container, 2 Electric motor, 2a Stator, 2b Rotor, 3 Compression mechanism part, 4 Drive shaft, 5 Discharge pipe, 6 Lubricating oil storage part, 6a Lubricating oil, 7 Suction muffler, 8 Suction pipe, 9 Connection pipe, 10 Low stage compression section, 11 Low stage cylinder, 12 Low stage rolling piston, 14 Low stage frame, 15 Low stage compression chamber, 16 Low stage discharge port, 17 Low stage discharge valve, 18 Low stage valve presser, 18a Rivet, 19 Low stage cover, 20 Low stage discharge space, 21 Low stage suction port, 23 Bypass port, 24 Bypass valve, 25 Bypass valve presser, 26 Low stage vane, 27 Low stage vane groove, 29 Rivet, 30 High stage compression part, 31 High stage cylinder, 32 High stage rolling piston, 34 High stage frame, 35 High stage compression chamber, 36 High stage discharge port, 37 High stage discharge valve, 38 High stage valve presser, 38a Rivet, 3 High-stage cover, 40 High-stage discharge space, 41 High-stage inlet, 42 High-stage vane, 43 High-stage vane groove, 50 Intermediate partition plate, 51 Intermediate flow path, 52 Discharge flow path, 53 Discharge pressure space, 60 Injector, 61 Injection pipe, 100 Two-stage compressor.

Claims (7)

A sealed container;
A compression mechanism disposed inside the sealed container;
An electric motor disposed inside the sealed container and serving as a drive source for the compression mechanism;
A drive shaft for transmitting the driving force of the electric motor to the compression mechanism;
With
The compression mechanism is
A lower frame,
A low-stage cylinder in which a first through-hole serving as a low-stage compression chamber is formed, and one opening of the first through-hole is closed by the low-stage frame;
An intermediate partition plate for closing the other opening of the first through hole;
A high-stage cylinder in which a second through-hole serving as a high-stage compression chamber is formed, and one opening of the second through-hole is closed by the intermediate partition plate;
A high frame that closes the other opening of the second through hole;
A low-stage rolling piston provided in an eccentric portion of the drive shaft and performing an eccentric rotational movement inside the low-stage compression chamber;
A high-stage rolling piston provided in an eccentric portion of the drive shaft and performing an eccentric rotational movement in the high-stage compression chamber;
A low-pressure vane that divides the inside of the low-stage compression chamber into a suction space and a compression space;
A high-pressure vane that divides the interior of the high-stage compression chamber into a suction space and a compression space;
Have
A low-stage frame, a low-stage cylinder, an intermediate partition plate, a high-stage cylinder and a high-stage frame are sequentially laminated to form a low-stage compression section and a high-stage compression section.
The refrigerant sucked from the pipe connected to the low-pressure suction port of the low-stage compression chamber of the low-stage compression section is compressed in the low-stage compression chamber, and the refrigerant is introduced into the high-stage compression chamber via an intermediate flow path. A rotary two-stage compressor that compresses again and discharges the refrigerant compressed in the high-stage compression chamber into a discharge pressure space that is an internal space of the sealed container,
A low-stage discharge port for discharging the refrigerant compressed in the low-stage compression chamber is formed in the low-stage frame;
A low-stage cover that covers the low-stage discharge port and forms a low-stage discharge space therein,
The intermediate flow path is formed through the low-stage frame, the low-stage cylinder and the intermediate partition plate, and communicates the low-stage discharge space and the high-stage compression chamber.
The rotary two-stage compressor is provided with a bypass mechanism that opens when the load is smaller than a predetermined load, and connects the low-stage discharge space and the discharge pressure space to the low-stage cover.   2. The rotary two-stage compressor according to claim 1, wherein the bypass mechanism opens when a pressure in the low-stage discharge space is higher than a pressure in the discharge pressure space by a predetermined value or more. In the compression mechanism section, the low-stage compression section is disposed above the high-stage compression section,
The bypass mechanism is
A bypass port formed in the low stage cover;
A valve that is provided to close the bypass port, deforms when a pressure of a predetermined value or more is applied, and opens the bypass port;
The rotary two-stage compressor according to claim 2, further comprising: When the rotation direction on the side closer to the distance from the low-stage discharge port to the bypass mechanism is a positive direction, with the central axis of the drive shaft as a reference,
The opening to the low-stage discharge space of the intermediate flow path is formed downstream of the bypass mechanism in the positive direction. The rotary two-stage compressor described in 1.   The rotary two-stage compressor according to any one of claims 1 to 4, wherein a pipe for injecting a refrigerant is connected to the low-stage discharge space.   6. The refrigerant suction position into the low-stage compression chamber is in substantially the same phase as the refrigerant suction position into the high-stage compression chamber. The rotary two-stage compressor described. When the rotation direction on the side where the distance from the low-stage vane to the suction port is near is the positive direction with respect to the central axis of the drive shaft,
The rotary two-stage compressor according to any one of claims 1 to 6, wherein the intermediate flow path is formed downstream of the suction port in the positive direction.

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