CN113266603B

CN113266603B - Diffuser of centrifugal compressor and centrifugal compressor

Info

Publication number: CN113266603B
Application number: CN202110710579.0A
Authority: CN
Inventors: 郭义; 李明; 王石柱
Original assignee: Shanghai Shangshi Aeroengine Co ltd
Current assignee: Shanghai Shangshi Aeroengine Co ltd
Priority date: 2021-06-25
Filing date: 2021-06-25
Publication date: 2022-06-28
Anticipated expiration: 2041-06-25
Also published as: CN113266603A

Abstract

The invention relates to the technical field of centrifugal compressors and discloses a diffuser of a centrifugal compressor and the centrifugal compressor. The diffuser comprises a fixed back plate, a plurality of blades, a pressure diaphragm box and an actuating mechanism, wherein the fixed back plate is annular, a plurality of groups of air holes are formed in the fixed back plate, each group of air holes comprises a first air hole and a second air hole, and the first air holes and the second air holes are uniformly distributed in the fixed back plate along the circumferential direction; the plurality of blades are circumferentially arranged on the fixed back plate and are rotatably connected with the fixed back plate, the first air holes are positioned in the area above the back of the rear edge of each blade, and the second air holes in the same group are positioned at the air outlets of the same blade; the pressure cap separates the pressure diaphragm chamber into a first air chamber and a second air chamber, a plurality of first air holes are communicated with the first air chamber, a plurality of second air holes are communicated with the second air chamber, one end of the actuating mechanism is connected to the pressure cap, the other end of the actuating mechanism is connected with a plurality of blades, and the actuating mechanism can drive the blades to rotate. The air flow separation is reduced, and the efficiency of the centrifugal compressor is higher.

Description

Diffuser of centrifugal compressor and centrifugal compressor

Technical Field

The invention relates to the technical field of centrifugal compressors, in particular to a diffuser of a centrifugal compressor and the centrifugal compressor.

Background

The centrifugal compressor is a fluid machine which applies work by radial acceleration under the action of centrifugal force generated by blades on gas, airflow in a rotor of the centrifugal compressor flows in from axial flow and flows out from radial flow, the centrifugal force is large, the speed of outlet airflow is high, and airflow separation is easily generated at the position of a channel between blades of the radial diffuser due to high speed of the airflow and high pressure, so that separation loss is caused; the air flow velocity is too fast, and shock waves are generated when the air flow velocity is accelerated at the contraction section of the blades of the radial diffuser, so that shock wave loss is caused. In order to improve the efficiency and the characteristics of the centrifugal compressor, adjustable blades are added in the design of a radial diffuser of the centrifugal compressor designed in the prior art, a commonly used adjustable blade actuating mechanism is actuated by hydraulic pressure or driven by a motor, the actuating mechanism is complex in structure and relates to active control of a control system, different active control input parameters are required to be provided for different working conditions, and the early design cost and the test cost are greatly increased.

Disclosure of Invention

Based on the above, the invention aims to provide a diffuser of a centrifugal compressor and the centrifugal compressor, which have the advantages of simple structure, convenience in disassembly, capability of automatic adjustment, reduction of air flow separation and improvement of the efficiency of the centrifugal compressor.

In order to achieve the purpose, the invention adopts the following technical scheme:

A diffuser for a centrifugal compressor comprising:

the fixed back plate is annular, a plurality of groups of air holes are formed in the back plate, each group of air holes comprises a first air hole and a second air hole, and the first air holes and the second air holes are uniformly distributed in the fixed back plate along the circumferential direction;

the blades are arranged on the fixed back plate at intervals along the circumferential direction of the fixed back plate, the front edges of the blades are rotatably connected with the fixed back plate, the first air holes are formed in the upper area of the back edge of each blade, and the second air holes in the same group are formed in the air outlet of the same blade;

the pressure diaphragm box is internally provided with a movable pressure cover, the pressure cover divides the pressure diaphragm box into a first air chamber and a second air chamber, a plurality of first air holes are communicated with the first air chamber, a plurality of second air holes are communicated with the second air chamber, and a through hole is formed in one side wall, located on the second air chamber, of the pressure diaphragm box;

actuating the mechanism, wear to locate the through-hole, the one end of actuating the mechanism connect in the pressure cap, the other end with a plurality of the blade is connected, it can along with the removal of pressure cap rotates to actuate the mechanism, in order to drive the blade rotates.

As a preferred embodiment of the diffuser of the centrifugal compressor, a ratio of the number of the first air holes to the number of the blades is 1/2.

As a preferred embodiment of a diffuser of a centrifugal compressor, the actuating mechanism includes:

and the limiting elastic piece is positioned in the second air chamber, one end of the limiting elastic piece is abutted to the pressure cover, and the other end of the limiting elastic piece is abutted to the side wall of the pressure diaphragm box.

As a preferred scheme of the diffuser of the centrifugal compressor, the diffuser further comprises:

the first air-entraining mechanism comprises a first air collecting pipe and a plurality of first air-dividing pipes, one end of one first air-dividing pipe is correspondingly communicated with one first air hole, the other ends of the plurality of first air-dividing pipes are communicated with the first air collecting pipe, and the first air collecting pipe is communicated with the first air chamber.

and the second air entraining mechanism comprises a second air collecting pipe and a plurality of second air distributing pipes, one end of one second air distributing pipe is correspondingly communicated with one second air hole, the other ends of the plurality of second air distributing pipes are communicated with the second air collecting pipe, and the second air collecting pipe is communicated with the second air chamber.

As a preferable aspect of a diffuser of a centrifugal compressor, the actuating mechanism further includes:

a follower rod located in the second air chamber and connected to the pressure cap, the follower rod being movable with movement of the pressure cap;

the rotating assembly penetrates through the through hole, one end of the rotating assembly is connected with the follower rod, the other end of the rotating assembly is connected with the plurality of blades, and the rotating assembly rotates along with the movement of the follower rod so as to drive the blades to rotate.

As a preferable aspect of a diffuser of a centrifugal compressor, the rotating assembly includes:

the direction-changing rotating shaft penetrates through the through hole, a guide groove is formed in the side wall of one end of the direction-changing rotating shaft, the guide groove is spiral, and the follower rod is connected with the guide groove and can move along the guide groove so as to drive the direction-changing rotating shaft to rotate;

and one end of the linkage piece is connected with the output end of the turning rotating shaft, and the other end of the linkage piece is connected with the plurality of blades so as to drive the blades to rotate.

As a preferable aspect of a diffuser of a centrifugal compressor, the link includes:

one end of the connecting rod is connected to the output end of the turning rotating shaft;

The rotating ring is connected with the other end of the connecting rod, guide grooves are formed in the blades in the length direction of the blades, a plurality of guide pins are arranged on the rotating ring at intervals, and one guide pin is inserted into one guide groove and can move along the guide groove.

As a preferred scheme of the diffuser of the centrifugal compressor, the connecting rods are provided with a plurality of connecting rods which are circumferentially spaced and uniformly distributed at the output end of the turning rotating shaft.

A centrifugal compressor comprises the diffuser of the centrifugal compressor in any technical scheme.

The beneficial effects of the invention are as follows:

the invention provides a diffuser of a centrifugal compressor, which comprises a fixed back plate, a plurality of blades, a pressure diaphragm box and an actuating mechanism, wherein the blades are arranged at intervals along the circumferential direction of the fixed back plate, all first air holes in the fixed back plate are communicated with a first air chamber, all second air holes are communicated with a second air chamber, namely, the air pressure in the first air chamber corresponds to the static pressure in the area above the back of the trailing edge of each blade, and the air pressure in the second air chamber corresponds to the static pressure at the air outlet of each blade. When the static pressure of the area above the back of the rear edge of the blade is not more than the static pressure of the air outlet of the blade, the blade angle of a diffuser of the centrifugal compressor is an original installation angle, and a pressure cover is almost abutted against the side wall of a first air chamber of a pressure diaphragm capsule; when airflow separation occurs, the static pressure of an area above the back of the rear edge of the blade is increased, accordingly, the air pressure in the first air chamber is increased, the pressure cover is pushed to move towards the side wall of the second air chamber, so that the actuating mechanism is driven to move, the actuating mechanism rotates along with the movement of the pressure cover and drives the blade to rotate, the airflow is changed by changing the angle of the blade, the airflow turning direction is reduced, and airflow separation is reduced; when the pressure cap is moved almost into abutment with the side wall of the second air chamber, the vane angle is adjusted to a maximum value. Through the structure, the air flow separation can be effectively prevented, and the efficiency of the press machine is improved; the angle of the blade can be automatically adjusted, the cost is saved, the adjustment is timely, and the efficiency is higher; meanwhile, the diffuser of the centrifugal compressor is simple in structure, the blade angle can be adjusted without elements such as a driving piece and a controller, the structural form and the installation mode are simple, and the mounting and dismounting are convenient.

The invention also provides a centrifugal compressor which comprises the diffuser of the centrifugal compressor, and the efficiency of the centrifugal compressor is higher.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings may be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.

FIG. 1 is a schematic view of a diffuser of a centrifugal compressor at a viewing angle according to an embodiment of the present invention;

FIG. 2 is a schematic view of a diffuser of a centrifugal compressor at another view angle according to an embodiment of the present invention;

FIG. 3 is an enlarged view of portion A of FIG. 1;

fig. 4 is a cross-sectional view of a diffuser for a centrifugal compressor according to an embodiment of the present invention.

In the figure:

1. fixing the back plate; 2. a blade; 3. a pressure bellows; 4. a pressure cap;

5. an actuating mechanism; 51. a limiting elastic part; 52. a follower rod; 53. a rotating assembly; 531. a turning rotating shaft; 532. a connecting rod; 533. a rotating ring; 534. a guide pin;

6. A first air-entraining mechanism; 61. a first gas collecting pipe; 62. a first gas distribution pipe; 63. a first outlet pipe;

7. a second air-entraining mechanism; 71. a second gas collecting pipe; 72. a second gas-dividing pipe; 73. a second outlet pipe;

8. rotating the pin shaft;

10. a first air hole; 20. a second air hole; 30. a first air chamber; 40. a second air chamber; 50. a guide groove; 60. a guide groove.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless expressly stated or limited otherwise, the recitation of a first feature "on" or "under" a second feature may include the recitation of the first and second features being in direct contact, and may also include the recitation that the first and second features are not in direct contact, but are in contact via another feature between them. Also, the first feature "on," "above" and "over" the second feature may include the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. "beneath," "under" and "beneath" a first feature includes the first feature being directly beneath and obliquely beneath the second feature, or simply indicating that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used based on the orientations and positional relationships shown in the drawings, and are only for convenience of description and simplicity of operation, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to be limiting.

As shown in fig. 1 to fig. 4, the embodiment provides a diffuser of a centrifugal compressor, the diffuser of the centrifugal compressor includes an annular fixed backplate 1, a rotating ring 533 and a plurality of blades 2, the plurality of blades 2 are uniformly arranged on the fixed backplate 1 at intervals along a circumferential direction, a leading edge of each blade 2 is rotatably connected with the fixed backplate 1 through a rotating pin 8, a plurality of groups of air holes are further opened on the fixed backplate 1, each group of air holes includes a first air hole 10 and a second air hole 20, the first air hole 10 and the second air hole 20 are uniformly distributed on the fixed backplate along a circumferential direction, the first air hole 10 is located in an upper area of a back portion of a back edge of each blade 2, and the second air holes 20 in the same group are located at an air outlet of the same blade 2. Specifically, this diffuser of centrifugal compressor still includes pressure diaphragm chamber 3 and actuating mechanism 5, be provided with mobilizable pressure lid 4 in the pressure diaphragm chamber 3, first air chamber 30 and second air chamber 40 are separated into with pressure diaphragm chamber 3 to pressure lid 4, a plurality of first gas pockets 10 all communicate with first air chamber 30, a plurality of second gas pockets 20 all communicate with second air chamber 40, the through-hole has been seted up on the pressure diaphragm chamber 3 lateral wall of second air chamber 40, actuating mechanism 5 wears to locate this through-hole, one end is connected in pressure lid 4, the other end is connected in swivel ring 533, should actuate mechanism 5 and can rotate along with pressure lid 4 removal, in order to drive blade 2 and rotate.

Since all the first air holes 10 are communicated with the first air chamber 30 and all the second air holes 20 are communicated with the second air chamber 40, the air pressure in the first air chamber 30 corresponds to the static pressure in the area above the back of the trailing edge of the blade 2, and the air pressure in the second air chamber 40 corresponds to the static pressure at the air outlet of the blade 2. When gas flows in the radial diffuser, if no gas flow separation occurs, the flow velocity of the area above the back of the blade 2 is higher than that of the area at the air outlet of the blade 2, and the static pressure is lower; when the air flow separation occurs, an air flow stagnation region occurs in the region above the back of the blade 2, and the flow velocity of the stagnation region is lower than that of the outlet region of the blade 2 and the static pressure is higher. When the static pressure of the area above the back of the rear edge of the blade 2 is not more than the static pressure of the air outlet of the blade 2, the angle of the blade 2 of the diffuser of the centrifugal compressor is an original installation angle, and the pressure cover 4 is almost abutted against the side wall of the first air chamber 30 of the pressure diaphragm capsule 3; when airflow separation occurs, the static pressure in the area above the back of the trailing edge of the blade 2 becomes higher, and accordingly, the air pressure in the first air chamber 30 becomes higher, so that the pressure cover 4 is pushed to move towards the side wall of the second air chamber 40, and the actuating mechanism 5 is driven to move, and the actuating mechanism 5 rotates along with the movement of the pressure cover 4, so that the blade 2 is driven to rotate.

The air flow is changed by changing the angle of the blade 2, so that the turning direction of the air flow is reduced, and the air flow separation is reduced; when pressure cover 4 is moved almost into abutment with the side wall of second plenum 40, vanes 2 are angularly adjusted to a maximum value. Through the structure, the function of airflow diversion direction can be changed, the minimum throat distance between the blades 2 can be adjusted, and the separation loss generated by airflow separation and the shock wave loss generated by airflow acceleration are reduced, so that the efficiency of the compressor is improved. The diffuser of the centrifugal compressor provided by the embodiment can automatically adjust the angle of the blades 2 in real time according to the static pressure difference of air flow between the blades 2, is timely in adjustment, simple in structure, free from increasing control input parameters and large number of test verifications, and low in design cost.

In this embodiment, the first air chamber 30 and the plurality of first air holes 10 are communicated through the first air-entraining mechanism 6, and the second air chamber 40 and the plurality of second air holes 20 are communicated through the second air-entraining mechanism 7. Specifically, the first air-entraining mechanism 6 comprises a first air collecting pipe 61, a first air outlet pipe 63 and a plurality of first air distributing pipes 62, the second air-entraining mechanism 7 comprises a second air collecting pipe 71, a second air outlet pipe 73 and a plurality of second air distributing pipes 72, each first air hole 10 is communicated with one first air distributing pipe 62, the plurality of first air distributing pipes 62 are all communicated with the first air collecting pipe 61, and the first air collecting pipe 61 is communicated with the first air chamber 30 through the first air outlet pipe 63; each second air hole 20 is communicated with one second air distributing pipe 72, the plurality of second air distributing pipes 72 are communicated with the second air collecting pipe 71, and the second air collecting pipe 71 is communicated with the second air chamber 40 through the second air outlet pipe 73. More specifically, the first gas collecting pipe 61 and the second gas collecting pipe 71 are both annular, the first gas distributing pipe 62 and the second gas distributing pipe 72 are both perpendicular and parallel to the fixed backplate 1, and the axes of the pressure capsule 3 and the fixed backplate 1 are located on the same straight line. The diffuser automatic adjustment of the centrifugal compressor provided by the embodiment does not need to be connected with a controller after installation, the size of the pressure diaphragm box 3 is small, the first air entraining mechanism 6 and the second air entraining mechanism 7 can be changed according to the layout of other parts of an engine, interference to other parts can not be caused when the compressor is dismounted or mounted, and the structural form and the installation mode are simple and convenient.

Preferably, the first gas collecting pipe 61 and the second gas collecting pipe 71 are both parallel to the fixed back plate 1, so that the diffuser of the centrifugal compressor is compact and regular in structure and convenient to mount and dismount; and the paths between each first air hole 10 and the first gas collecting pipe 61 are the same, and the paths between each second air hole 20 and the second gas collecting pipe 71 are the same, that is, the pressure of the first air chamber 30 corresponds to the average static pressure of a plurality of first air holes 10, and the average static pressure of the second air chamber 40 corresponds to the average static pressure of a plurality of second air holes 20, so that the adjustment accuracy of the diffuser of the centrifugal compressor is improved.

Preferably, the ratio of the number of the first air holes 10 to the number of the plurality of the blades 2 is 1/2. I.e. one first air hole 10 per every other blade 2. This arrangement can achieve the maximum effect with the minimum number of first air holes 10. Of course, in other embodiments, the ratio of the number of the first air holes 10 to the number of the plurality of blades 2 may be designed according to actual needs. More preferably, the diameter of the first and second air holes 10 and 20 ranges from 2mm to 3 mm. Of course, the diameters of the first air hole 10 and the second air hole 20 may be determined according to the specific size of the stationary backplate 1.

Preferably, the pressure cover 4 is made of rubber, and the pressure cover 4 made of rubber and the wall surface piece of the pressure diaphragm box 3 can form a good sealing environment, so that the phenomenon that the first air chamber 30 and the second air chamber 40 leak air mutually to influence the normal operation of a diffuser of the centrifugal compressor is avoided.

Further, the actuating mechanism 5 includes a follower rod 52 and a rotating component 53, the follower rod 52 is located in the second air chamber 40 and connected to the pressure cover 4, when the pressure cover 4 moves under the pressure difference between the first air chamber 30 and the second air chamber 40, the follower rod 52 moves therewith, the rotating component 53 penetrates through the through hole on the pressure film box 3, one end of the rotating component 53 is connected to the follower rod 52, the other end is connected to the plurality of blades 2, and the follower rod 52 can drive the rotating component 53 to rotate when moving, so as to drive the blades 2 to rotate. Specifically, the rotating assembly 53 is composed of a turning rotating shaft 531 and a linkage member, the turning rotating shaft 531 penetrates through a through hole on the pressure diaphragm capsule 3, a spiral guide groove 50 is formed in a side wall of one end of the turning rotating shaft 531, the follower rod 52 is connected with the guide groove 50 and can move along the guide groove 50 to drive the turning rotating shaft 531 to rotate, one end of the linkage member is connected with an output end of the turning rotating shaft 531, and the other end of the linkage member is connected with the plurality of blades 2 to drive the blades 2 to rotate. When the pressure cover 4 moves, the follower rod 52 drives the turning rotating shaft 531 to rotate, that is, the turning rotating shaft 531 realizes the axial conversion into the circumferential motion, and the turning rotating shaft 531 drives the linkage member to rotate again, so that all the blades 2 connected with the linkage member finally rotate, and the angle adjustment of the blades 2 is realized.

In this embodiment, the linkage includes a connecting rod 532 and a rotating ring 533, one end of the connecting rod 532 is connected to the output end of the turning rotating shaft 531, the rotating ring 533 is connected to the other end of the connecting rod 532, a guide groove 60 is formed in the blade 2 along the length direction of the blade 2, a plurality of guide pins 534 are arranged on the rotating ring 533 at intervals, and one guide pin 534 is inserted into one guide groove 60 and can move along the guide groove 60. Due to the limiting function of the guide groove 60, the initial state of the blade 2 is controllable, an additional limiting mechanism is not required to be installed, the blade 2 can only rotate within a design range, and high controllability is achieved. When a pressure difference chamber occurs between the first air chamber 30 and the second air chamber 40, the pressure cover 4 moves, and the direction-changing rotation shaft 531 drives the rotation ring 533 to rotate, so that each guide pin 534 on the rotation ring slides along the guide groove 60, and each blade 2 rotates around the rotation pin 8, thereby realizing the angle adjustment of the blade 2.

Preferably, the connecting rod 532 is provided in plurality, and the plurality of connecting rods 532 are spaced and uniformly arranged. The plurality of links 532 can provide enough force to drive the rotating ring 533 to rotate, so that the single link 532 is prevented from being broken easily due to overlarge stress. Illustratively, there are three links 532, and three links 532 are arranged in a trefoil arrangement.

In another embodiment, the linkage may include a plurality of connecting rods, the connecting rods are spaced along the circumferential direction of the turning rotating shaft 531, and two ends of one connecting rod are respectively connected to the output end of the turning rotating shaft 531 and one blade 2. When a pressure difference chamber occurs between the first air chamber 30 and the second air chamber 40, the pressure cover 4 moves, and the turning rotation shaft 531 rotates the connection rod, thereby rotating each blade 2. Of course, in this embodiment, each blade 2 is correspondingly provided with a limiting mechanism to limit the rotation angle of the blade 2.

In order to better control the variation range of the rotation angle of the vane 2, the actuating mechanism 5 further includes a limiting elastic member 51, the limiting elastic member 51 is located in the second air chamber 40, one end of the limiting elastic member 51 abuts against the pressure cover 4, and the other end abuts against the sidewall of the pressure diaphragm box 3. When the air flow separation occurs, the pressure cover 4 moves the compression limit elastic member 51 toward a direction of compressing the second air chamber 40, and when the pressure difference is balanced with the restoring force of the limit elastic member 51, the pressure cover 4 stops moving. Therefore, the change range of the rotation angle of the blade 2 can be accurately controlled according to the elastic coefficients of the different limiting elastic pieces 51. The angle variation range of the blades 2 is also influenced by the rotation angle range of the turning rotating shaft 531 and the pressure difference of the pressure cover 4, in the embodiment, the angle variation range of the blades 2 is not more than 5 degrees, the diameter of the pressure diaphragm capsule 3 is not more than 50mm, the rotation angle range of the turning rotating shaft 531, the pressure difference of the pressure cover 4 and the elastic coefficient of the limiting elastic part 51 can be set according to the characteristics of the centrifugal compressor, and therefore accurate controllable adjustment of the rotation angle of the blades 2 is achieved.

Experiments prove that compared with the centrifugal compressor without the adjustable diffuser, the efficiency of the diffuser of the centrifugal compressor provided by the embodiment can be improved by 2% at 100% of the rotating speed, and can be improved by 3% at 90% of the rotating speed, so that the pneumatic performance of a rotor of the centrifugal compressor is greatly optimized.

The embodiment also provides the centrifugal compressor, which comprises the diffuser of the centrifugal compressor, and the working efficiency of the centrifugal compressor using the diffuser is higher.

It is to be noted that the foregoing description is only exemplary of the invention and that the principles of the technology may be employed. Those skilled in the art will appreciate that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements and substitutions will now be apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in some detail by the above embodiments, the invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the invention, and the scope of the invention is determined by the scope of the appended claims.

Claims

1. A diffuser for a centrifugal compressor, comprising:

The fixing back plate (1) is annular, a plurality of groups of air holes are formed in the fixing back plate (1), and each group of air holes comprises a first air hole (10) and a second air hole (20); the first air holes (10) and the second air holes (20) are uniformly distributed on the fixed back plate (1) along the circumferential direction;

the blades (2) are arranged on the fixed back plate (1) at intervals along the circumferential direction of the fixed back plate (1), the front edges of the blades (2) are rotatably connected with the fixed back plate (1), the first air holes (10) are positioned in the upper area of the back edge of each blade (2), and the second air holes (20) in the same group are positioned at the air outlets of the same blades (2);

the pressure diaphragm capsule (3) is internally provided with a movable pressure cover (4), the pressure cover (4) divides the pressure diaphragm capsule (3) into a first air chamber (30) and a second air chamber (40), a plurality of first air holes (10) are communicated with the first air chamber (30), a plurality of second air holes (20) are communicated with the second air chamber (40), and a through hole is formed in one side wall, located on the second air chamber (40), of the pressure diaphragm capsule (3);

The actuating mechanism (5) penetrates through the through hole, one end of the actuating mechanism (5) is connected to the pressure cover (4), the other end of the actuating mechanism is connected with the plurality of blades (2), and the actuating mechanism (5) can rotate along with the movement of the pressure cover (4) so as to drive the blades (2) to rotate;

the actuating mechanism (5) comprises a follower rod (52) and a rotating assembly (53), the follower rod (52) is located in the second air chamber (40) and is connected with the pressure cover (4), the follower rod (52) can move along with the movement of the pressure cover (4), the rotating assembly (53) penetrates through the through hole, one end of the rotating assembly (53) is connected with the follower rod (52), the other end of the rotating assembly (53) is connected with the plurality of blades (2), and the rotating assembly (53) rotates along with the movement of the follower rod (52) to drive the blades (2) to rotate.

2. Diffuser for a centrifugal compressor according to claim 1, characterized in that the ratio of the number of first air holes (10) to the number of blades (2) is 1/2.

3. Diffuser for a centrifugal compressor according to claim 1, characterized in that said actuating means (5) comprise:

And the limiting elastic piece (51) is positioned in the second air chamber (40), one end of the limiting elastic piece (51) abuts against the pressure cover (4), and the other end of the limiting elastic piece abuts against the side wall of the pressure diaphragm box (3).

4. The centrifugal compressor diffuser of claim 1, further comprising:

the first air-entraining mechanism (6) comprises a first air collecting pipe (61) and a plurality of first air-dividing pipes (62), one end of one first air-dividing pipe (62) is correspondingly communicated with one first air hole (10), the other ends of the plurality of first air-dividing pipes (62) are communicated with the first air collecting pipe (61), and the first air collecting pipe (61) is communicated with the first air chamber (30).

5. The centrifugal compressor diffuser of claim 1, further comprising:

the second air-entraining mechanism (7) comprises a second air collecting pipe (71) and a plurality of second air-dividing pipes (72), one end of one second air-dividing pipe (72) is correspondingly communicated with one second air hole (20), the other ends of the plurality of second air-dividing pipes (72) are communicated with the second air collecting pipe (71), and the second air collecting pipe (71) is communicated with the second air chamber (40).

6. Diffuser for a centrifugal compressor according to claim 1, characterized in that said rotating assembly (53) comprises:

the turning rotating shaft (531) penetrates through the through hole, a guide groove (50) is formed in the side wall of one end of the turning rotating shaft (531), the guide groove (50) is spiral, and the follow-up rod (52) is connected with the guide groove (50) and can move along the guide groove (50) to drive the turning rotating shaft (531) to rotate;

one end of the linkage piece is connected to the output end of the turning rotating shaft (531), and the other end of the linkage piece is connected with the plurality of blades (2) so as to drive the blades (2) to rotate.

7. The centrifugal compressor diffuser of claim 6, wherein the linkage member comprises:

one end of the connecting rod (532) is connected to the output end of the turning rotating shaft (531);

the rotating ring (533) is connected with the other end of the connecting rod (532), a guide groove (60) is formed in the blade (2) along the length direction of the blade (2), a plurality of guide pins (534) are arranged on the rotating ring (533) at intervals, and one guide pin (534) is inserted into one guide groove (60) and can move along the guide groove (60).

8. The diffuser of a centrifugal compressor according to claim 7, wherein a plurality of connecting rods (532) are provided, and the plurality of connecting rods (532) are circumferentially spaced and uniformly distributed at the output end of the turning rotating shaft (531).

9. A centrifugal compressor comprising a diffuser of a centrifugal compressor as claimed in any one of claims 1 to 8.