WO2019240480A1

WO2019240480A1 - Centrifugal compressor

Info

Publication number: WO2019240480A1
Application number: PCT/KR2019/007035
Authority: WO
Inventors: 김진성; 한현욱; 김규영; 박정민
Original assignee: 엘지전자 주식회사
Priority date: 2018-06-12
Filing date: 2019-06-11
Publication date: 2019-12-19
Also published as: KR102545557B1; CN112292534A; KR20190140729A

Abstract

A centrifugal compressor comprises: a motor having a rotational shaft; a first volute casing having a first inlet, a first volute, and a gas chamber separated from the first volute and the first inlet; a first impeller connected to one side of the rotational shaft and rotatably accommodated inside the first volute casing; a vaneless diffuser forming a diffuser path after an outlet of the first impeller; a second volute casing having a second volute, an outlet, and a second inlet through which a fluid flowing from the first volute is introduced; and a second impeller connected to the other side of the rotational shaft and rotatably accommodated inside the second volute casing, wherein at least one of the first volute casing and the vaneless diffuser has a gas adjustment path for allowing the gas chamber and the diffuser path to be in communication with each other, and a gas outlet of the gas adjustment path faces an area within the diffuser path, starting from a middle location between the front end of the diffuser path and the rear end of the diffuser path, and ending at the rear end of the diffuser path.

Description

Centrifugal compressor

The present invention relates to a compressor for compressing a fluid, and more particularly to a centrifugal compressor for compressing a gas using centrifugal force.

A centrifugal compressor is a device which rotates a vane wheel in a casing and compresses gas by the centrifugal force.

The centrifugal compressor may be configured to compress a gas such as a refrigerant gas. In this centrifugal compressor, when the driving force of the motor is transmitted to the impeller and the impeller is rotated, gas is introduced into the impeller by the rotating force of the impeller, and the gas is driven by the impeller As the flow increases, the kinetic energy increases, and the gas having the increased kinetic energy passes through the diffuser, and the kinetic energy is converted into a constant pressure, thereby increasing the pressure. The gas whose pressure is increased is sequentially discharged through the discharge port communicating with the volute and the balltute, and then discharged outside the centrifugal compressor.

The diffuser is to convert the kinetic energy of the gas into a static pressure, one example of the diffuser may be a vaneless diffuser (Vaneless Diffuser) formed in the gas flow direction gradually smaller cross section of the flow path through the gas, the other example of the diffuser It may be a vane diffuser (Vane Diffuser) that the cross-sectional area of the passage passing through is gradually formed in the gas flow direction and a plurality of vanes are installed in this passage.

The centrifugal compressor can be configured to adjust its capacity, and one example of the adjustable capacity centrifugal compressor is disclosed in US Pat. No. 9,157,446 B2 (October 13, 2015). This centrifugal compressor includes a first impeller provided in the main refrigerant flow path, a vane diffuser disposed downstream of the first impeller and having a plurality of vanes, and a second impeller and a second impeller provided in the main refrigerant flow path downstream of the first impeller. A refrigerant circulation passage connecting downstream and downstream of the first impeller, the refrigerant circulation passage comprising a plurality of circulation nozzles for injecting refrigerant, the outlets of the plurality of circulation nozzles being at least partially disposed radially outward of the leading edge of the vane .

It is an object of the present invention to provide a centrifugal compressor capable of injecting gas to an optimum position of a vaneless diffuser, thereby minimizing pressure loss coefficient and maximizing efficiency and adjusting capacity.

A centrifugal compressor according to an embodiment of the present invention includes a motor having a rotating shaft; A first volute casing having a first inlet and a first volute formed therein and a gas chamber partitioned from each of the first volute and the first inlet; A first impeller connected to one side of the rotating shaft and rotatably received in the first volute casing; A vaneless diffuser defining a diffuser passage after the outlet of the first impeller; A second volute casing having a second inlet into which the fluid flowing from the first volute flows and having a second volute and an outlet; A second impeller connected to the other side of the rotating shaft and rotatably received in the second volute casing, wherein at least one of the first volute casing and the vaneless diffuser is provided with a gas control passage communicating the gas chamber and the diffuser passage; In addition, the gas outlet of the gas regulating passage may be directed to an area from the intermediate position between the front end of the diffuser passage and the rear end of the diffuser passage to the rear end of the diffuser passage.

The gas outlet may be closer to the rear end of the diffuser passage, either at the leading end of the diffuser passage and the rear end of the diffuser passage.

The gas outlet may be directed to an area ranging from 50% to 75% of the distance from the leading end of the diffuser passage to the rear end of the diffuser passage relative to the leading edge of the diffuser passage.

The gas outlet may be directed to a position of 50% or 75% of the distance from the tip of the diffuser passage to the rear end of the diffuser passage relative to the tip of the diffuser passage.

The gas control passage may include a gradient path inclined obliquely with respect to the axial center of the first impeller and including a gas outlet. The gradient can have an angle of inclination with the diffuser passageway. The angle of inclination may be between 30 ° and 80 °.

The gas regulating passage may further include a communication passage connecting the gas chamber and the gradient passage and parallel to the shaft center.

The cross-sectional area of the gas chamber may be smaller than that of the first volute and larger than that of the gas outlet.

According to an embodiment of the present invention, the gas of the gas control passage may be injected to a position that can minimize the pressure loss coefficient and maximize the efficiency.

In addition, the gas passing through the gradient passage of the gas control passage is inclined to the diffuser passage to minimize the flow resistance when the gas is injected into the diffuser passage.

1 is a view showing a refrigeration cycle apparatus is applied centrifugal compressor according to an embodiment of the present invention,

2 is a cross-sectional view showing a centrifugal compressor according to an embodiment of the present invention;

3 is an enlarged cross-sectional view of portion A shown in FIG.

4 is a side view showing a comparative example of the diffuser according to the embodiment of the present invention;

5 is a side view showing an example of a diffuser according to an embodiment of the present invention;

6 is a side view showing another example of the diffuser according to the embodiment of the present invention;

7 is a side view showing another example of the diffuser according to the embodiment of the present invention;

8 is a graph illustrating a comparison of the pressure loss coefficients of the examples of the present invention and the comparative examples;

9 is a graph illustrating the comparison between the efficiency of the Examples and Comparative Examples of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a refrigeration cycle apparatus is applied centrifugal compressor according to an embodiment of the present invention, Figure 2 is a sectional view showing a centrifugal compressor according to an embodiment of the present invention, Figure 3 is A shown in Figure 2 It is a section enlarged section.

As shown in FIG. 1, the centrifugal compressor 1 of the present embodiment may constitute a refrigeration cycle apparatus together with the condenser 2, the expansion mechanism 3, and the evaporator 4, and is compressed in the centrifugal compressor 1. After cooling, the refrigerant discharged from the centrifugal compressor 1 may be sequentially passed through the condenser 2, the expansion mechanism 3, and the evaporator 4, and then sucked into the centrifugal compressor 1.

The centrifugal compressor 1 may be connected to the evaporator 4 and the suction passage 5, and may be connected to the condenser 2 and the discharge passage 6.

The centrifugal compressor 1 may be constituted by a multi-stage compression type centrifugal compressor capable of compressing the refrigerant in multiple stages. In this case, the centrifugal compressor 1 may include a plurality of compression mechanisms C1 connected by connecting passages C3 (see FIG. 2). (C2) may be included.

The centrifugal compressor 1 may compress the refrigerant in the first compression mechanism C1, which is one of the plurality of compression mechanisms C1 and C2, and then discharge the refrigerant into the connection flow path C3, and the connection flow path C3. The refrigerant discharged into the second compressor mechanism C2, which is another one of the plurality of compression mechanisms C1 and C2, may be compressed, and the refrigerant compressed in the second compressor C2 may be discharged to the discharge passage 6. Through the condenser (2).

The refrigeration cycle apparatus having the above-described centrifugal compressor 1 has a bypass flow path 7 (see FIG. 1) for bypassing some of the refrigerant compressed by the second compression mechanism C2 to the first compression mechanism C1. The volume of the centrifugal compressor 1 may be further controlled by the amount of the refrigerant discharged from the second compression mechanism C2 and introduced into the first compression mechanism C1 through the bypass passage 7. Can be.

This bypass flow path 7 may be formed by a tube at least partially positioned outside of the centrifugal compressor 1.

As shown in FIG. 1, the bypass passage 7 may have an inlet end 7A connected to at least one of the second compression mechanism C2, the discharge passage 6, and the condenser 2, and the first It may have an outlet end 7B connected to the compression mechanism C1.

The inlet end 7A can be connected to a plurality of the second compression mechanism C2, the discharge passage 6 and the condenser 2, and the second compression mechanism C2, the discharge passage 6 and the condenser 2 It is possible to connect only to any one of

When the inlet end 7A is connected to the second compression mechanism C2, the inlet end 7A may be connected to the outlet 52 (see FIG. 2) or the second volute V2 of the second compression mechanism C2. have. The outlet end 7B may be connected to the first volute casing 20 described later of the first compression mechanism C1.

At least a portion of the bypass flow path 7 is located outside the centrifugal compressor 1, the inlet end 7A is connected to the second compression mechanism C2, and the outlet end 7B is connected to the first compression mechanism C1. It can be formed by a tube.

The bypass flow path 7 is not limited to having the inlet end 7A and the outlet end 7B as described above, and the bypass flow path 7 is formed inside the centrifugal compressor 1 (for example, the motor housing). Of course, it is also possible to be formed in (12).

On the other hand, the bypass flow path 7 may be provided with a flow regulator 8 (see Fig. 1) for adjusting the flow rate of the gas passing through the bypass flow path 7, the flow regulator 8 is adjustable in its opening degree Valve and the like. When the opening degree of the flow regulator 8 is increased, the flow rate of the gas injected into the first compression mechanism C1 through the bypass passage 7 after being compressed by the second compression mechanism C2 may be increased. On the contrary, when the opening degree of the flow regulator 8 is reduced, the flow rate of the gas injected into the first compression mechanism C1 through the bypass passage 7 after being compressed by the second compression mechanism C2 may be reduced. .

Hereinafter, the centrifugal compressor 1 will be described in detail with reference to FIGS. 2 and 3.

The centrifugal compressor 1 includes a motor 10, a first volute casing 20, a first impeller 30, a vaneless diffuser 40, a second volute casing 50, and a second impeller. (60).

The motor 10 may have a rotation shaft 11. One side of the rotating shaft 11 may extend into the first volute casing 20, and the other side of the rotating shaft 11 may extend into the second volute casing 50.

The motor 10 may include a motor housing 12 having a space formed therein. The motor housing 12 may be formed long in the axial direction of the rotation shaft 11.

The motor 10 may further include a rotor 13 and a stator 14 accommodated in the motor housing 12. The rotor 13 may be disposed at the outer circumference of the rotating shaft 11 and may be rotated together with the rotating shaft 11. The stator 14 may be disposed inside the motor housing 14 to surround the outer circumference of the rotor 13.

The connection passage C3 may be formed in the motor housing 12. One end of the connection flow path C3 may face the first bulkhead casing 20, and the other end of the connection flow path C3 may face the second volute casing 50. The connection passage C3 may communicate the outlet 22 of the first volute casing 20 with the inlet 51 of the second volute casing 50. The gas exiting the first volute V1 of the first volute casing 20 sequentially connects the connection flow path C3 formed in the outlet 22 of the first volute casing 20 and the motor housing 12. After passing through, it may flow into the inlet 51 of the second volute casing 50.

The first volute casing 20 may be fastened to the motor housing 12 by a fastening member such as a screw, and a first impeller accommodation space in which the first impeller 30 may be accommodated may be formed. . The first impeller accommodation space may communicate with the first inlet 21 and may be a space that is larger than the first inlet 21.

The first volute casing 20 includes a first inlet 21 and a first volute V1 formed therein and a gas chamber S partitioned from each of the first inlet 21 and the first volute V1. Can be formed.

The first volute casing 20 may be hollow. The inner circumferential surface of the first volute casing 20 may form an inlet 21 for guiding gas to the first impeller 20. The first volute V1 and the gas chamber S may be formed between the inner and outer circumferential surfaces of the first volute casing 20.

The first volute V1 may be formed in a circular shape or an arc shape, and may be formed in a shape that gradually expands in the flow direction of the gas (that is, the turning direction of the gas).

The gas chamber S may be formed to be spaced apart from the first volute V1 between the inner and outer circumferential surfaces of the first volute casing 20. The distance between the gas chamber S and the inlet 21 may be shorter than the distance between the first volute V1 and the inlet 21. The gas chamber S may be formed in a circular shape or an arc shape.

A gas control passage P may be connected to the gas chamber S, and the gas of the gas chamber S may be injected into the diffuser passage D1 of the vaneless diffuser 40 through the gas control passage P. .

The centrifugal compressor 1 may include a plurality of gas control passages P connected to the gas chambers S, and the gas of the gas chambers S may have a plurality of gas diffusers passages D1 through the gas control passages P. It may be sprayed while being distributed to a position (see FIGS. 5 to 7).

Each gas control passage (P) may include a gas outlet (T) for guiding gas to the diffuser passage (D1), the gas control passage (P) is in communication with the diffuser passage (D1) by the gas outlet (T). Can be.

In the centrifugal compressor, a gas in one gas chamber S may be injected into the diffuser passage D1 through a plurality of gas outlets T. The cross-sectional area of the gas chamber S may be smaller than the cross-sectional area of the first volute V1 and larger than the cross-sectional area of the gas outlet T.

Here, the cross-sectional area of the gas chamber S, the cross-sectional area of the first volute V1, and the cross-sectional area of the gas outlet T may be cross-sectional areas of a direction orthogonal to the axial direction (that is, the radial direction).

The first volute casing 20 may be formed with an outlet 22 through which the gas of the first volute V1 passes to exit the first volute casing 20. One end of the outlet 22 formed in the first volute casing 20 may be connected to the first volute V1, and the other end of the outlet 22 may be connected to the connection flow path C3.

On the other hand, the first volute casing 20 has a bypass connecting passage 29 (see FIGS. 2 and 3) for communicating the gas chamber S with the outlet end 7B of the bypass passage 7 (see FIG. 1). Can be formed. Some of the gas discharged from the second volute casing 50 may pass through the bypass passage 7 and the bypass connection passage 29 sequentially, and then flow into the gas chamber S, and the gas chamber S After spreading in a wide), it can be dispersed in a plurality of gas control passage (P).

The first impeller 30 may be connected to one side of the rotation shaft 11. The first impeller 30 may be rotatably received in the first volute casing 20. In the first impeller 30, the inlet 31 through which gas is introduced may face the axial direction of the rotating shaft 11, and the outlet 32 through which the gas is taken out may face the radial direction of the rotating shaft 11, and Can be sucked in the axial direction and discharged in the centrifugal direction. The first impeller 30 may be rotatably accommodated in a first impeller accommodation space formed between the diffuser body 41 and the first volute casing 20, which will be described later, of the vaneless diffuser 40.

The vaneless diffuser 40 may form a diffuser passage D1 after the outlet 32 of the first impeller 30. The diffuser passage D1 may be a communication path for communicating the first impeller accommodation space in which the first impeller 30 is accommodated and the first volute V1, and from the outlet 32 of the first impeller 30 to the first impeller 30. It may be defined as a passage located between one volute (V1).

The diffuser passage D1 may have an annular shape in which the overall shape is hollow, and may be elongated in a radial direction perpendicular to the axial direction.

The vaneless diffuser 40 may be disposed between the motor 10 and the first volute casing 20. The vaneless diffuser 40 may have a rotating shaft through hole through which the rotating shaft 11 penetrates. A part of the vaneless diffuser 40 may be disposed between the motor 10 and the first impeller 30, and the vaneless diffuser 40 may include a first impeller accommodation space and a rotor in which the first impeller 30 is accommodated. The space of the motor 10 in which the 13 and the stator 13 are accommodated can be partitioned.

The vaneless diffuser 40 may be formed by a plurality of members. The vaneless diffuser 40 may include a diffuser body 41.

The diffuser body 41 may have an inner region A facing the first impeller 30 and an outer region B surrounding the inner region A and not facing the first impeller 30.

The vaneless diffuser 40 may further include a diffuser cover 46. The diffuser cover 46 may be disposed in the first volute casing 20 to face the outer region B. As shown in FIG. The gas exiting the outlet 32 of the first impeller 30 may pass between the outer region B of the diffuser body 41 and the diffuser cover 46, and the first volute in the diffuser passage D1. May flow into (V1).

The centrifugal compressor may be provided with a gas control passage P for communicating the gas chamber S and the diffuser passage D1 to at least one of the first volute casing 20 and the vaneless diffuser 40.

Gas control passage (P) may be a plurality of spaced apart in the circumferential direction.

Gas control passage (P) may include a gradient path (P1) inclined obliquely with respect to the axial center (C) of the first impeller 30, the gradient path (P1) may include a gas outlet (T). Can be. Gas passing through the gradient passage (P1) may be injected into the diffuser passage (D1) after passing through the gas outlet (T).

The gradient path P1 may be formed to have an inclination angle θ of an acute angle with the diffuser passage D1. The gradient path P1 may be gradientd to have an inclination angle θ of 30 ° to 80 °.

The gas control passage P may further include a communication passage P2 connecting the gas chamber S and the gradient passage P1. The communication path P2 may be elongated in a direction parallel to the axis center C.

The first volute casing 20, the first impeller 30, and the vaneless diffuser 40 may constitute a first compression mechanism C1 that primarily compresses the refrigerant introduced into the centrifugal compressor 1. have.

The second volute casing 50 may have a second inlet 51 into which the fluid flowing in the first volute V1 flows. The second volute casing 50 may be formed with a second volute V2 and an outlet 52.

The second volute casing 50 may be disposed opposite to the first volute casing 50. The second volute casing 50 may be fastened to the motor housing 12 by a fastening member such as a screw, and a second impeller accommodation space may be formed therein in which the second impeller 60 may be accommodated. .

The second impeller accommodation space may be in communication with the second inlet 51.

A diffuser passage D2 is formed between the second volute casing 50 and the motor housing 12 to guide the gas flowing at the outlet 62 of the second impeller 60 to the second volute V2. Can be. The diffuser passage D2 formed between the second volute casing 50 and the motor housing 12 includes a second impeller accommodation space and a second ball formed between the second volute casing 50 and the motor housing 12. It may be located between the lute (V2), the gas exiting the outlet 62 of the second impeller 60 may be guided to the second volute (V2).

The second volute V2 may be formed in a circular shape or an arc shape, and may be formed in a shape that gradually expands in the flow direction of the gas.

The outlet 52 of the second volute casing 50 may be formed in communication with the second volute V2, and discharges the gas flowing in the second volute V2 to the outside of the centrifugal compressor 1. I can guide you.

The second impeller 60 may be connected to the other side of the rotation shaft 11. The second impeller 60 may be rotatably received in the second volute casing 50. In the second impeller 60, the inlet 61 through which gas is introduced may face the axial direction of the rotation shaft 11, and the outlet 62 through which the gas is drawn may face the radial direction of the rotation shaft 11, and Can be sucked in the axial direction and discharged in the centrifugal direction. The second impeller 60 may be rotatably accommodated in the second impeller accommodation space formed between the second volute casing 50 and the motor housing 12.

The second volute casing 50 and the second impeller 60 are compressed by the first compression mechanism C1 and then secondly compress the refrigerant introduced through the connection flow path C3 secondly. Can be configured.

On the other hand, the centrifugal compressor (1) configured as described above is a pressure loss according to the position where the gas control passage (P) injects gas into the diffuser passage (D1), that is, the gas outlet (T) position of the gas control passage (P). Coefficient of pressure loss and efficiency may be different, and the gas outlet T of the gas control passage is preferably formed at a position capable of maximizing the efficiency while minimizing the pressure loss coefficient.

Figure 4 is a side view showing a comparative example of the diffuser according to an embodiment of the present invention, Figure 5 is a side view showing an example of a diffuser according to an embodiment of the present invention, Figure 6 is a diffuser according to an embodiment of the present invention Another example is a side view, and FIG. 7 is a side view showing another example of a diffuser according to an embodiment of the present invention. 8 is a graph in which the pressure loss coefficients of the examples of the present invention and the comparative example are shown in comparison, and FIG. 9 is a graph in which the efficiency of the examples of the present invention is compared with the comparative example.

As shown in FIG. 4, the gas outlet T ′, which is a comparative example of the gas outlet T of the present embodiment (see FIGS. 5 to 7), may have a front end Pa of the diffuser passage D1 among the diffuser passages D1. From the intermediate position Pc between the rear end Pb of the diffuser passage D1 to the tip Pa of the diffuser passage D1, it is more at the tip Pa of the diffuser passage D1 than the intermediate position Pc. If you are located close.

The tip Pa of the diffuser passage D1 may be defined as the outlet 32 of the first impeller 30, and the rear end Pb of the diffuser passage D1 may be the vaneless diffuser 40, in particular the diffuser body (D). 41) may be defined as the outermost perimeter.

Meanwhile, as shown in FIGS. 5 to 7, the gas outlet T of the present embodiment is disposed between the front end Pa of the diffuser passage D1 and the rear end Pb of the diffuser passage D1 in the diffuser passage D1. It may face the area from the intermediate position (Pc) of the to the rear end (Pb) of the diffuser passage (D1).

The gas outlet T of the present embodiment is a second radius R2 determined by Equation 2 from a position that is the first radius R1 determined by Equation 1 based on the axial center C of the first impeller 30. It is possible to be formed facing the area up to the position.

[Equation 1]

R1 = (Rimp + Rdiff) / 2

[Equation 2]

R2 = (Rimp + 3 * Rdiff) / 4

Here, Rimp is the radius of the first impeller 30, and Rdiff is the radius of the vaneless diffuser 40.

As shown in FIGS. 6 and 7, the gas outlet T of the present embodiment has a rear end of the diffuser passage D1 between the front end Pa of the diffuser passage D1 and the rear end Pb of the diffuser passage D1. Closer to Pb).

As shown in FIGS. 5 and 6, the gas outlet T of the present exemplary embodiment may be formed from the distal end Pa of the diffuser passage D1 to the diffuser passage D1 based on the distal end Pa of the diffuser passage D1. To the rear end Pb may be directed to an area in the range of 50% to 75% of the distance L.

An example of the gas outlet T of the present embodiment may be formed to face the first radius R1 determined by Equation 1 based on the axis center of the first impeller 30. In this case, as shown in FIG. 5, the gas outlet T is the rear end Pb of the diffuser passage D1 from the front end Pa of the diffuser passage D1 with respect to the front end Pa of the diffuser passage D1. ) Can be at a location that is 50% of the distance L. That is, in one example of the gas outlet T, the distance from the front end Pa of the diffuser passage D1 to the gas outlet T is the rear end Pb of the diffuser passage D1 from the front end Pa of the diffuser passage D1. This is the case formed at a position 0.5 times the distance L. In this case, the gas outlet T may be formed to face the position of the first radius R1 determined by Equation 1 based on the axial center C of the first impeller 30.

Another example of the gas outlet T of the present embodiment may be formed to face the position of the second radius R2 determined by Equation 2 based on the axis center of the first impeller 30. In this case, as shown in FIG. 6, the gas outlet T is the rear end Pb of the diffuser passage D1 from the tip Pa of the diffuser passage D1 with respect to the front end Pa of the diffuser passage D1. ) May be at a location that is 75% of the distance (L). That is, in another example of the gas outlet T, the distance from the front end Pa of the diffuser passage D1 to the gas outlet T is the rear end Pb of the diffuser passage D1 from the front end Pa of the diffuser passage D1. Is formed at a position that is 0.75 times the distance (L).

As another example of the gas outlet T of the present embodiment, as shown in FIG. A position exceeding 75% of the distance L to the rear end Pb may be directed to a position inside the rear end Pb of the diffuser passage D1. That is, in another example of the gas outlet T, the distance from the front end Pa of the diffuser passage D1 to the gas outlet T is the rear end of the diffuser passage D1 from the front end Pa of the diffuser passage D1. Pb) up to 0.75 times the distance L and less than one time.

8 and 9 show only results of comparing the pressure loss coefficients and the efficiencies of the gas outlets T 'and T, which are different from each other, and all other configurations are measured under the same conditions.

As in the present embodiment, the distance from the leading edge Pa of the diffuser passage D1 to the gas outlet T is the distance from the leading edge Pa of the diffuser passage D1 to the rear end Pb of the diffuser passage D1 ( In the case of more than 0.5 times and less than 1 times L), the pressure loss coefficient is lower than 65% for the comparative example as shown in FIG. 8, and as shown in FIG. 9, the efficiency is higher than 70% for the comparative example. Higher than

On the other hand, in the case of the comparative example, the pressure loss coefficient is higher than that of the embodiment of the present invention by more than 65%, and the efficiency is lower than that of the embodiment of the invention by less than 70 &.

8 and 9, it can be seen that the pressure loss coefficient is lower and the efficiency is higher than that of the comparative example.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims

A motor having a rotating shaft;

A first volute casing having a first inlet and a first volute formed therein and a gas chamber partitioned from each of the first volute and the first inlet;

A first impeller connected to one side of the rotation shaft and rotatably received in the first volute casing;

A vaneless diffuser defining a diffuser passage after the outlet of the first impeller;

A second volute casing which has a second inlet into which the fluid flowing in the first volute flows and is formed with a second volute and an outlet;

A second impeller connected to the other side of the rotation shaft and rotatably received in the second volute casing;

At least one of the first volute casing and the vaneless diffuser is provided with a gas control passage for communicating the gas chamber and the diffuser passage,

The gas outlet of the gas control passage is a centrifugal compressor toward an area from the intermediate position between the front end of the diffuser passage and the rear end of the diffuser passage of the diffuser passage to the rear end of the diffuser passage.
The method of claim 1,

And the gas outlet is closer to the rear end of the diffuser passage among the leading end of the diffuser passage and the rear end of the diffuser passage.
The method of claim 1,

Wherein said gas outlet is directed toward a region ranging from 50% to 75% of the distance from the leading end of said diffuser passage to the rear end of said diffuser passage relative to the leading edge of said diffuser passage.
The method of claim 1,

And the gas outlet is at a position of 50% or a position of 75% of the distance from the front end of the diffuser passage to the rear end of the diffuser passage with respect to the front end of the diffuser passage.
The method of claim 1,

The gas control passage

And a gradient path inclined obliquely with respect to the axial center of the first impeller and including the gas outlet.
The method of claim 5,

Wherein said gradient has an acute inclination angle with said diffuser passageway.
The method of claim 6,

The inclination angle is 30 ° to 80 ° centrifugal compressor.
The method of claim 5,

The gas control passage

And a communication path connecting the gas chamber and a gradient path and parallel to the axis center.
The method of claim 1,

The cross-sectional area of the gas chamber is smaller than the cross-sectional area of the first volute, and larger than the cross-sectional area of the gas outlet.