WO2021240605A1

WO2021240605A1 - Two-stage single-screw compressor, and refrigeration and air-conditioning device

Info

Publication number: WO2021240605A1
Application number: PCT/JP2020/020556
Authority: WO
Inventors: 慎栗田
Original assignee: 三菱電機株式会社
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2021-12-02

Abstract

A two-stage single-screw compressor having: a second compression unit for further compressing a refrigerant compressed by a first compression unit; and a rotary shaft inserted into the first compression unit and the second compression unit, and provided with a first screw rotor and a second screw rotor. In the first compression unit, a first compression chamber is formed by a helical structure of a first gate rotor and the first screw rotor, and a second compression chamber is formed by a helical structure of a second gate rotor and the first screw rotor. The first gate rotor and the second gate rotor are arranged facing one another with the rotary shaft therebetween. A first injection port and a second injection port through which a refrigerant is injected are formed respectively opening into the first compression chamber and the second compression chamber. In the second compression unit, a third compression chamber is formed by a helical structure of a third gate rotor and the second screw rotor. The second compression chamber and the third compression chamber are formed on the same side relative to the rotary shaft. The total opening area of the first injection port is larger than the total opening area of the second injection port.

Description

Two-stage single screw compressor and refrigerating air conditioner

The present disclosure relates to a two-stage single-screw compressor for refrigerating and air-conditioning, and a refrigerating and air-conditioning device equipped with a two-stage single-screw compressor.

Conventionally, as a compressor that compresses the refrigerant circulated in the refrigerating and air-conditioning system, a single screw compressor having a configuration in which a screw rotor and a gate rotor are housed in a casing is known. The low-temperature low-pressure gas refrigerant sucked into the single-screw compressor is compressed in the compression chamber, becomes a high-temperature and high-pressure gas refrigerant, and is discharged from the single-screw compressor. If the compression process of the refrigerant in the compression chamber is continued during the operation of the single screw compressor, the temperature of the refrigerant in the compression chamber rises. Therefore, the temperature of the inner peripheral surface of the screw rotor and the casing also rises, and the screw rotor and the casing thermally expand.

If the temperature of the refrigerant in the compression chamber rises excessively, the outer circumference of the screw rotor and the inner circumference of the casing may come into contact with each other, causing seizure of the screw rotor. Further, the rotation shaft of the screw rotor may be deformed due to the contact between the outer circumference of the screw rotor and the inner circumference of the casing. Therefore, when the temperature of the refrigerant discharged from the compression chamber becomes higher than the preset temperature, the liquid refrigerant is injected into the compression chamber to cool the refrigerant discharged from the compression chamber and suppress the rise in the refrigerant temperature. The technique is known (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-64331

A two-stage single screw compressor is known as a type of single screw compressor. The two-stage single-screw compressor compresses the refrigerant to a high compression ratio with a multi-stage compression unit. In the two-stage single screw compressor, the first-stage compression section compresses the refrigerant from the suction pressure to the intermediate pressure, and the second-stage compression section compresses the refrigerant from the intermediate pressure to the discharge pressure. As a two-stage single screw compressor, a one in which the first-stage compression unit is configured by a twin gate rotor system and the second-stage compression unit is configured by a monogate rotor system is known. The twin gate rotor method is a method in which two gate rotors are fitted to a screw rotor. In the twin gate rotor type compression unit, two gate rotors are arranged at symmetrical positions across the rotation axis of the screw rotor, and two compression chambers are formed at symmetrical positions across the rotation axis of the screw rotor. There is. The monogate rotor method is a method in which one gate rotor is fitted to a screw rotor. In the monogate rotor type compression unit, one compression chamber is formed according to the position of the gate rotor. The first-stage screw rotor and the second-stage screw rotor are provided in series with the rotating shaft.

In the second stage compression unit configured by the monogate rotor method, the internal pressure differs between the side where the gate rotor is provided across the rotating shaft and the side where the gate rotor is not provided. The space on the side where the gate rotor is not provided is the atmosphere of the intermediate pressure refrigerant gas discharged from the compression section of the first stage, and the internal pressure of the space on the side where the gate rotor is provided forms a compression chamber. This is because the discharge pressure has risen. Therefore, in the second stage compression section, the differential pressure between the intermediate pressure and the discharge pressure acts on the rotary shaft, and the gas load due to the differential pressure may cause the rotary shaft to bend to the side where the gate rotor is not provided. .. As described above, when the discharge temperature of the refrigerant rises above a predetermined temperature, the deformation of the rotating shaft in the second stage compression portion may become more remarkable. Since the screw rotor of the first-stage compression part and the screw rotor of the second-stage compression part are provided in series with the rotation shaft, the deformation of the rotation shaft that occurs in the second-stage compression part is the compression of the first stage. It also affects the department. That is, when the rotation axis is deformed, the internal spaces of the two compression chambers of the first-stage compression section become non-uniform, and the transition of the internal pressures of the two compression chambers becomes different. There is a possibility that a load will be applied in the radial direction. As a result, a load may be applied to the bearing of the rotating shaft provided in the casing, and the life may be shortened. Therefore, it is required to suppress the deformation of the rotating shaft when the temperature of the discharged refrigerant rises. However, when the configuration of the compressor described in Patent Document 1 is adopted for the first-stage compression unit, the injection mechanism of Patent Document 1 is not configured to execute the injection process in consideration of the deformation of the rotating shaft. Deformation of the rotating shaft cannot be suppressed.

The present disclosure has been made against the background of the above-mentioned problems, and is a two-stage single-screw compressor with improved reliability by suppressing deformation of the rotating shaft and reducing the load on the bearing of the rotating shaft. And a refrigerating air conditioner equipped with a two-stage single screw compressor.

The two-stage single screw compressor according to the present disclosure includes a first compression unit that compresses the refrigerant, a second compression unit that further compresses the refrigerant compressed by the first compression unit, the first compression unit, and the first compression unit. 2 A rotating shaft through which a compression portion is inserted, a screw that receives one end of the rotating shaft, and a casing in which the first compression portion, the second compression portion, the rotating shaft, and the bearing are housed. A two-stage single-screw compressor having the first compression portion, the first screw rotor attached to the rotating shaft and having a spiral groove formed therein, so as to be fitted with the spiral groove of the first screw rotor. It has a first gate rotor provided and a second gate rotor provided so as to be fitted with the spiral groove of the first screw rotor, and the first gate rotor and the second gate rotor are rotated. A first compression chamber is formed by the spiral groove of the first gate rotor and the first screw rotor, and the spiral groove of the second gate rotor and the first screw rotor is arranged so as to face each other with a shaft interposed therebetween. A second compression chamber is formed by the above, and at least one first injection port that opens into the first compression chamber and injects the refrigerant, and at least one that opens into the second compression chamber and injects the refrigerant. A second injection port is formed, and the second compression portion is provided so as to be fitted to the spiral groove of the second screw rotor and the second screw rotor which is attached to the rotating shaft and has a spiral groove formed therein. A third compression chamber is formed by the third gate rotor and the spiral groove of the second screw rotor, and the second compression chamber and the third compression chamber are formed. It is formed inside the casing on the same side with respect to the rotation axis, and the total opening area of the first injection port is larger than the total opening area of the second injection port.

According to the present disclosure, the total opening area of the second injection port of the second compression chamber formed on the same side as the side where the third compression chamber of the second compression portion is formed with respect to the rotation shaft is the rotation shaft. On the other hand, it is larger than the total opening area of the first injection port of the first compression chamber formed on the side different from the side where the third compression chamber is formed. That is, the amount of the refrigerant injected into the first compression chamber is larger than the amount of the refrigerant injected into the second compression chamber. Therefore, it is possible to cancel the load on the rotating shaft from the radial direction from the second compression chamber to the first compression chamber, which is generated in the first compression portion due to the deformation of the rotating shaft generated in the second compression portion. can. As a result, deformation of the rotating shaft is suppressed, the load on the bearing of the rotating shaft is reduced, the life of the bearing can be shortened, and the reliability of the two-stage single screw compressor can be improved. ..

It is a refrigerant circuit diagram of the refrigerating and air-conditioning apparatus provided with the two-stage single screw compressor which concerns on embodiment of this disclosure. It is the schematic sectional drawing of the two-stage single screw compressor which concerns on embodiment of this disclosure. It is sectional drawing of the 1st compression part of the two-stage single screw compressor which concerns on embodiment of this disclosure. It is sectional drawing of the 2nd compression part of the two-stage single screw compressor which concerns on embodiment of this disclosure. It is a figure which conceptually shows the injection port of the two-stage single screw compressor which concerns on embodiment of this disclosure. It is a figure which shows the pressure transition of the 1st compression chamber and the 2nd compression chamber of the 1st compression part of the two-stage single screw compressor of the comparative example. It is a figure which shows the pressure transition of the 1st compression chamber and the 2nd compression chamber of the 1st compression part of the two-stage single screw compressor which concerns on embodiment of this disclosure.

Hereinafter, embodiments of the two-stage single screw compressor according to the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and can be variously modified without departing from the gist of the present disclosure. In addition, the present disclosure includes all combinations of configurations that can be combined among the configurations shown in the following embodiments. Further, the compressor shown in the drawings shows an example of equipment to which the compressor of the present disclosure is applied, and the compressors shown in the drawings do not limit the equipment to which the present disclosure is applied. Further, in the following description, terms indicating directions (for example, "top", "bottom", "right", "left", "front", "rear", etc.) are appropriately used for ease of understanding. These are for illustration purposes only and are not intended to limit this disclosure. Further, in each figure, those having the same reference numerals are the same or equivalent thereof, which are common to the whole text of the specification. In each drawing, the relative dimensional relationship or shape of each component may differ from the actual one.

Embodiment 1.
FIG. 1 is a refrigerant circuit diagram of a refrigerating and air-conditioning apparatus provided with a single-screw compressor according to an embodiment of the present disclosure. A refrigerant circuit 200 is formed in the refrigerating and air-conditioning device 100. The refrigerant circuit 200 has a configuration in which a single screw compressor 10, an evaporator 201, a liquid reservoir (not shown), an expansion valve 202, a condenser 203, and the like are connected by a refrigerant pipe to form a closed loop. The single screw compressor 10 compresses and discharges the refrigerant, and is a two-stage single screw compressor as described later. The refrigerant discharged from the single screw compressor 10 is condensed by the condenser 203, depressurized by the expansion valve 202, and evaporated by the evaporator 201. As the working refrigerant flowing through the refrigerant circuit 200, for example, R410 refrigerant, which is a high-pressure refrigerant, is used.

An injection tube 204 is provided between the expansion valve 202 and the condenser 203. The injection pipe 204 branches from the pipe connecting the expansion valve 202 and the condenser 203, and is connected to the single screw compressor 10. The liquid refrigerant is injected into the single screw compressor 10 via the injection pipe 204.

FIG. 2 is a schematic cross-sectional view of the single screw compressor according to the embodiment of the present disclosure. The single screw compressor 10 of the first embodiment has a cylindrical casing 11. The single screw compressor 10 has a compression unit 20 housed in a casing 11, an electric motor 50, and a rotating shaft 60. The rotating shaft 60 is provided on the central shaft portion of the casing 11, and one end thereof is supported by a bearing (not shown).

A motor rotor 51 of the motor 50 is provided at one end of the rotating shaft 60. The motor rotor 51 is rotated by the drive of the electric motor 50, and the rotation shaft 60 is rotated by the rotation of the motor rotor 51. The electric motor 50 can have a variable speed by using an inverter (not shown).

The compression unit 20 is divided into a first compression unit 20A and a second compression unit 20B inside the casing 11. That is, the single screw compressor 10 is a two-stage single screw compressor. The rotating shaft 60 inserts the first compression unit 20A and the second compression unit 20B. The first compression unit 20A is the first stage in the two-stage single screw compressor, and is on the lower stage side. The second compression unit 20B is the second stage in the two-stage single screw compressor, and is on the higher stage side. The first compression unit 20A is configured by a twin gate rotor system, and the second compression unit 20B is configured by a monogate rotor system.

FIG. 3 is a cross-sectional view of the first compression portion of the single screw compressor according to the embodiment of the present disclosure. FIG. 3 cuts the single screw compressor 10 at the position of lines AA of FIG. 2 and is shown from the left side of FIG. The first compression unit 20A will be described with reference to FIGS. 2 and 3. The first compression unit 20A includes a first screw rotor 30, a first gate rotor 31, and a second gate rotor 32. The first screw rotor 30, the first gate rotor 31, and the second gate rotor 32 are provided inside a cylindrical cylinder 205 (see FIG. 5) provided in the casing 11. The first gate rotor 31 and the second gate rotor 32 are fitted to the first screw rotor 30. The first screw rotor 30 is attached to the rotating shaft 60. A screw groove 30A, which is a plurality of spiral grooves, is formed on the outer peripheral surface of the first screw rotor 30. The first gate rotor 31 and the screw groove 30A mesh with each other, and the first compression chamber 33 is formed in the space between the inner wall of the casing 11. The second gate rotor 32 and the screw groove 30A mesh with each other, and the second compression chamber 34 is formed in the space between the inner wall of the casing 11. The first screw rotor 30 rotates with the rotation of the rotary shaft 60, the volume of the first compression chamber 33 is reduced, the working refrigerant is compressed, and the first screw rotor 30 rotates with the rotation of the rotary shaft 60. 2 The volume of the compression chamber 34 is reduced, and the working refrigerant is compressed.

The first slide valve 35 adjusts the internal volume ratio of the first compression chamber 33. The second slide valve 36 adjusts the internal volume ratio of the second compression chamber 34. The first slide valve 35 and the second slide valve 36 are configured to be driven along the rotation shaft 60 by a slide mechanism (not shown). In FIG. 2, the first slide valve 35 and the second slide valve 36 are omitted.

FIG. 4 is a cross-sectional view of a second compression portion of the single screw compressor according to the embodiment of the present disclosure. FIG. 4 cuts the single screw compressor 10 at the position of line BB in FIG. 2 and is shown from the left side of FIG. The second compression unit 20B will be described with reference to FIGS. 2 and 4. The second compression unit 20B has a second screw rotor 40 and a third gate rotor 41. A third gate rotor 41 is fitted to the second screw rotor 40. A screw groove 40A, which is a plurality of spiral grooves, is formed on the outer peripheral surface of the second screw rotor 40. The third gate rotor 41 and the screw groove 40A mesh with each other, and the third compression chamber 43 is formed in the space between the inner wall of the casing 11. Along with the rotation of the rotating shaft 60, the second screw rotor 40 rotates, the volume of the third compression chamber 43 is reduced, and the working refrigerant is compressed.

The third slide valve 44 adjusts the internal volume ratio of the third compression chamber 43. The third slide valve 44 is configured to be driven along the rotation shaft 60 by a slide mechanism (not shown). In FIG. 2, the third slide valve 44 is omitted.

As shown in FIG. 2, in the casing 11, the first gate rotor 31 is arranged below the rotating shaft 60, the second gate rotor 32 is arranged above the rotating shaft 60, and the third gate rotor 41 is arranged above the rotating shaft 60. It is located above 60. That is, inside the casing 11, the third gate rotor 41 is arranged on the side where the second gate rotor 32 is arranged with respect to the rotating shaft 60. In other words, in the casing 11, the third compression chamber 43 is formed on the same side as the side on which the second compression chamber 34 is formed with respect to the rotating shaft 60.

Further, as shown in FIG. 3, the first compression chamber 33 and the second compression chamber 34 are formed so as to face each other at positions symmetrical with each other by 180 degrees with the rotation axis 60 interposed therebetween. Therefore, since the first compression chamber 33 and the second compression chamber 34 face each other at a position of 180 degrees with respect to the rotation shaft 60, there is an advantage that the gas load of the refrigerant acting in the radial direction with respect to the rotation shaft 60 can be reduced. be.

FIG. 5 is a diagram conceptually showing the injection port of the single screw compressor according to the embodiment of the present disclosure. FIG. 5A shows a second injection port 38 that opens into the second compression chamber 34. FIG. 5B shows a first injection port 37 that opens into the first compression chamber 33. In the present embodiment, in the first compression unit 20A, the injection pipe 204 shown in FIG. 1 is connected to the side surface of the casing 11. Then, as shown in FIG. 5A, a second refrigerant passage 207 communicating the injection pipe 204 and the second compression chamber 34 is formed in the cylinder 205. The end of the second refrigerant passage 207 is the second injection port 38. Further, as shown in FIG. 5B, a first refrigerant passage 206 communicating the injection pipe 204 and the first compression chamber 33 is formed in the cylinder 205 described above. The end of the first refrigerant passage 206 is the first injection port 37.

The first injection port 37 is formed so that the cross-sectional shape cut along the plane orthogonal to the flow direction of the refrigerant in the first refrigerant passage 206 is circular. Further, the second injection port 38 is formed so that the cross-sectional shape cut along the plane orthogonal to the flow direction of the refrigerant in the second refrigerant passage 207 is circular. Then, as shown in FIGS. 5A and 5B, the diameter ΦD1 of the second injection port 38 is smaller than the diameter ΦD2 of the first injection port 37.

Here, the operation of the single screw compressor 10 will be described. The electric motor 50 for driving the single screw compressor 10 is activated by receiving a signal from an inverter (not shown). When the drive of the single screw compressor 10 is started by starting the electric motor 50, the operating refrigerant circulating in the refrigerant circuit 200 is sucked into the first compression chamber 33 and the second compression chamber 34 of the first compression unit 20A. The suction of the operating refrigerant into the first compression chamber 33 and the second compression chamber 34 is completed at the same timing, and the refrigerant having substantially the same mass is sucked into the first compression chamber 33 and the second compression chamber 34. After the suction of the operating refrigerant is completed, the volumes of the first compression chamber 33 and the second compression chamber 34 are reduced by the rotation of the first screw rotor 30 due to the rotation of the rotating shaft 60, and the internal pressure is increased. The timing at which the operating refrigerant is discharged from the first compression chamber 33 is adjusted by changing the axial position of the first screw rotor 30 of the first slide valve 35. Similarly, the timing at which the operating refrigerant is discharged from the second compression chamber 34 is adjusted by changing the axial position of the first screw rotor 30 of the second slide valve 36.

When the discharge gas temperature of the operating refrigerant becomes higher than the preset value, the liquid refrigerant guided from the injection pipe 204 passes through the first injection port 37 and the second injection port 38, and the first compression chamber 33 and the second are used. It is injected into the compression chamber 34. In the present embodiment, as described above, the diameter of the second injection port 38 opened in the second compression chamber 34 is larger than the diameter of the first injection port 37 opened in the first compression chamber 33. There is. Therefore, the amount of the liquid refrigerant injected into the second compression chamber 34 is larger than the amount of the refrigerant injected into the first compression chamber 33. That is, when the liquid refrigerant is injected, the second compression chamber 34 acts to allow more liquid refrigerant to flow in than the first compression chamber 33.

The operating refrigerant discharged from the first compression chamber 33 and the second compression chamber 34 is sucked into the third compression chamber 43 of the second compression unit 20B. The operating refrigerant sucked into the third compression chamber 43 is further compressed in the third compression chamber 43, discharged to the refrigerant circuit 200 shown in FIG. 1, and circulates in the refrigerant circuit 200.

The effects of this embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram showing pressure transitions between the first compression chamber and the second compression chamber of the first compression portion of the single screw compressor of the comparative example. FIG. 7 is a diagram showing pressure transitions between the first compression chamber and the second compression chamber of the first compression portion of the single screw compressor according to the embodiment of the present disclosure. In FIGS. 6 and 7, the horizontal axis is the volume of the compression chamber, and the vertical axis is the pressure in the compression chamber.

The second compression section 20B of the single screw compressor 10 is a monogate rotor system, and an intermediate pressure operating refrigerant is sucked into the third compression chamber 43 from the first compression section 20A. As the rotation of the second screw rotor 40 reduces the internal volume of the third compression chamber 43, and when the refrigerant is compressed, the internal pressure of the third compression chamber 43 increases. On the other hand, the lower side of the rotating shaft 60 of the second compression unit 20B is a refrigerant atmosphere with an intermediate pressure. Therefore, a pressure difference is generated between the upper side and the lower side of the rotary shaft 60, and the load of the gas refrigerant due to this differential pressure, that is, the gas load is applied in the radial direction from the upper side of the rotary shaft 60. As a result, the rotating shaft 60 bends downward and deforms. When a refrigerant having a high saturation pressure, for example, R410A, is used, this gas load becomes larger and the deformation of the rotating shaft 60 becomes larger.

The rotating shaft 60 is also deformed in the first compression portion 20A on the lower stage side due to the gas load acting on the rotating shaft 60 from the radial direction in the second compression portion 20B on the higher stage side. As described above, in the first compression unit 20A, two first compression chambers 33 and a second compression chamber 34 are formed in the vertical direction with the rotation shaft 60 interposed therebetween. When the rotating shaft 60 is deformed downward as described above due to the influence of the second compression unit 20B, the internal gap of the first compression chamber 33 and the internal gap of the second compression chamber 34 may become non-uniform. That is, as the rotary shaft 60 is deformed downward, the gap between the first screw rotor 30 and the casing 11 in the first compression chamber 33 above the rotary shaft 60 is expanded, and the second compression chamber below the rotary shaft 60 is expanded. The gap between the first screw rotor 30 and the casing 11 in 34 is reduced. Since the internal leakage of the refrigerant increases in the first compression chamber 33 in which the gap is expanded as in the second compression chamber 34 in which the gap is reduced, the internal pressure of the first compression chamber 33 is higher than the internal pressure of the second compression chamber 34. To change.

At this time, when the diameter of the first injection port 37 and the second injection port 38 are the same, the inflow amount of the liquid refrigerant flowing into the first compression chamber 33 and the second compression chamber 34 is the same. Then, even if the injection of the liquid refrigerant is performed, as described above, the internal pressure of the second compression chamber 34 in which the gap is expanded is higher than the internal pressure of the first compression chamber 33 in which the gap is reduced. It will change with pressure. That is, as shown in FIG. 5, the acupressure diagram of the second compression chamber 34 in which the above-mentioned gap is expanded has a shape bulging more than the acupressure diagram of the first compression chamber 33 in which the above-mentioned gap is reduced. Will be shown. As a result, the gas load applied in the radial direction from above to the rotary shaft 60 is maintained, the rotary shaft 60 remains deformed downward, and the bearing of the rotary shaft 60 may deteriorate.

On the other hand, in the present embodiment, the diameter of the first injection port 37 is set to be larger than the diameter of the second injection port 38. Therefore, according to the present embodiment, the inflow amount of the liquid refrigerant flowing into the first compression chamber 33 below the rotary shaft 60 is the inflow amount of the liquid refrigerant flowing into the second compression chamber 34 above the rotary shaft 60. Can be larger than. Therefore, since the density in the first compression chamber 33 rises as compared with the second compression chamber 34 and the pressure rises, the transition of the internal pressure in the first compression chamber 33 is brought closer to the transition of the internal pressure in the second compression chamber 34. Can be done. That is, as shown in FIG. 7, the acupressure diagram of the first compression chamber 33 can be brought closer to the acupressure diagram of the second compression chamber 34. As a result, it is possible to cancel the gas load applied in the radial direction from above with respect to the rotating shaft 60. In other words, the gas load on the rotating shaft 60 from the radial direction from the second compression chamber 34 to the first compression chamber 33 is cancelled. Therefore, the downward deformation of the rotating shaft 60 is suppressed, the load on the bearing is reduced, and the life of the bearing can be shortened. That is, according to the present embodiment, the reliability of the two-stage single screw compressor can be improved.

In the present disclosure, one first injection port 37 is formed in the first compression chamber 33, and one second injection port 38 is formed in the second compression chamber 34, but the number of injection ports is limited to this. is not it. For example, a plurality of injection ports may be formed in both or one of the first compression chamber 33 and the second compression chamber 34. In this case, the total opening area of the injection ports formed in the first compression chamber 33, that is, the total opening area is set to be larger than the total opening area of the injection ports formed in the second compression chamber 34.

10 single screw compressor, 11 casing, 20 compression part, 20A first compression part, 20B second compression part, 30 first screw rotor, 30A screw groove, 31 first gate rotor, 32 second gate rotor, 33 first Compression chamber, 34 2nd compression chamber, 35 1st slide valve, 36 2nd slide valve, 37 1st injection port, 38 2nd injection port, 40 2nd screw rotor, 40A screw groove, 41 3rd gate rotor, 43 3rd compression chamber, 44th 3rd slide valve, 50 electric motor, 51 motor rotor, 60 rotary shaft, 100 refrigeration and air conditioning device, 200 refrigerant circuit, 201 condenser, 202 expansion valve, 203 evaporator, 204 injection pipe, 205 cylinder, 206 first refrigerant passage, 207 second refrigerant passage.

Claims

A first compression unit that compresses the refrigerant, a second compression unit that further compresses the refrigerant compressed by the first compression unit, a rotation shaft that inserts the first compression unit and the second compression unit, and the rotation. A two-stage single-screw compressor comprising a bearing that receives one end of a shaft, a first compression section, a second compression section, a rotating shaft, and a casing in which the bearing is housed.
The first compression portion includes a first screw rotor attached to the rotating shaft and formed with a spiral groove, a first gate rotor provided so as to fit the spiral groove of the first screw rotor, and the first gate rotor. It has a second gate rotor provided to fit the spiral groove of the 1-screw rotor.
The first gate rotor and the second gate rotor are arranged so as to face each other with the rotation axis interposed therebetween.
A first compression chamber is formed by the first gate rotor and the spiral groove of the first screw rotor.
A second compression chamber is formed by the second gate rotor and the spiral groove of the first screw rotor.
At least one first injection port that opens into the first compression chamber and injects the refrigerant, and at least one second injection port that opens in the second compression chamber and injects the refrigerant are formed.
The second compression portion includes a second screw rotor attached to the rotating shaft and formed with a spiral groove, and a third gate rotor provided so as to fit the spiral groove of the second screw rotor. death,
A third compression chamber is formed by the third gate rotor and the spiral groove of the second screw rotor.
The second compression chamber and the third compression chamber are formed inside the casing on the same side with respect to the rotation axis.
A two-stage single screw compressor in which the total opening area of the first injection port is larger than the total opening area of the second injection port.
The two-stage single screw compressor according to claim 1, wherein the first injection port and the second injection port have a circular cross-sectional shape, and the diameter of the first injection port is larger than that of the second injection port. ..
A refrigerating air conditioner including the two-stage single screw compressor according to claim 1 or 2.