CN113374706B

CN113374706B - Multistage centrifugal blower

Info

Publication number: CN113374706B
Application number: CN202110693126.1A
Authority: CN
Inventors: 铁善奎
Original assignee: Xu Chunqing
Current assignee: Wuhan Chenxin Fluid Control Environmental Protection Equipment Co ltd
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2024-05-24
Anticipated expiration: 2041-06-22
Also published as: CN113374706A

Abstract

The invention belongs to the technical field of blower production, in particular to a multistage centrifugal blower, which aims at the problems that the multistage centrifugal blower has a plurality of stages, a gas flow channel is long, the gas flow speed is uneven, the gas flow speed entering a next-stage impeller is seriously deviated from a design value, the flow loss is large, and the efficiency of the blower is reduced. The impeller and the reflux ring are arranged in the invention, so that the gas can move in the shell in a direct-current mode, the gas circulation channel is short, the gas flow velocity is more uniform, and the loss in the circulation process is less.

Description

Multistage centrifugal blower

Technical Field

The invention relates to the technical field of blower production, in particular to a multistage centrifugal blower.

Background

The centrifugal blower is a constant pressure blower, and has the advantages of continuous air supply, balanced operation, high efficiency, simple structure, low noise, small external dimension and weight, few wearing parts and the like compared with the positive displacement blower. The centrifugal blower is divided into a multi-stage centrifugal blower and a single-stage centrifugal blower. The single-stage fans use high rotation speed to achieve the required wind pressure and wind quantity, the flow channels of more stages of fans are short, the flow channel loss among multiple stages is reduced, and the wind quantity is large but the wind pressure of the fans is relatively small. The multistage fan utilizes a step-by-step pressurizing mode to improve the wind pressure, and is characterized in that the wind pressure is large, but the wind quantity is relatively small, the outlet pressure and the actual wind quantity of the centrifugal fan are greatly influenced by the change of the air inlet temperature or the density, the pressure generated when the air inlet temperature is the highest (the density is the lowest) is the lowest for a given air inlet quantity, and the required power is reduced along with the increase of the air inlet temperature.

The multistage centrifugal blower has simple structure, easy manufacture and low cost, and has gradually replaced Roots blower in recent years, and is widely used in the fields of sewage treatment, aquaculture, smelting, material conveying and the like.

Disclosure of Invention

The invention provides a multistage centrifugal blower, which aims to solve the problems that in the prior art, the multistage centrifugal blower has a plurality of stages, a gas flow channel is long, and particularly, after the air flow at the outlet of a previous stage impeller passes through a reflux device, the air flow speed is uneven, the air flow speed entering the next stage impeller is seriously deviated from a design value, and the flow loss is large, so that the efficiency of the blower is reduced.

In order to achieve the above purpose, the present invention adopts the following technical scheme: the utility model provides a multistage centrifugal blower, includes the shell that establishes the cavity and be the cylinder in, circular hole has been seted up at one side terminal surface center of shell, and circular hole embeds and is equipped with sealed bearing two, and sealed bearing two has cup jointed the main shaft in, and the main shaft is located the one end of shell and be connected with the shaft coupling, and the shaft coupling is connected with driving motor two, the position that one side end wall of shell is located the top of circular hole is provided with the gas transmission mouth, and one side end wall gas transmission mouth of shell, shell inner wall equidistance welding has a plurality of water conservancy diversion circle, and the center of water conservancy diversion circle is provided with the air inlet, and the position that the main shaft is located between two adjacent water conservancy diversion circles is provided with the wheel seat, and the wheel seat outer wall is provided with the impeller, the one end welding that the shell inner wall is located the water conservancy diversion circle and is close to the gas transmission mouth has the backward flow ring, and backward flow ring equidistance is provided with a plurality of backward flow mouth.

Further, the circumferential inner wall of the backflow ring is matched with the tail end of the outer wall of the adjacent wheel seat in size, and a sealing device is arranged between the circumferential inner wall of the backflow ring and the tail end of the outer wall of the wheel seat, so that gas is prevented from flowing out of a gap between the backflow ring and the wheel seat by the sealing device, and uneven gas flow rate is prevented.

Further, one side of the guide ring, which is close to the gas transmission port, is provided with an inward concave cambered surface, one side of the guide ring, which is far away from the gas transmission port, is provided with a plane perpendicular to the side wall of the shell, and the guide ring with the cambered surface plays a role in guiding, so that gas can stably enter the gas inlet and the impeller of the guide ring at the next stage.

Further, an air inlet pipe is welded on one side end wall of the shell, a flange is arranged at the upper end of the air inlet pipe, the air inlet pipe is communicated with the air delivery port, a filter screen is clamped on the upper portion of the inner wall of the air inlet pipe, and a shock wave soot blower is mounted on the inner wall of the air inlet pipe.

Further, the air inlet pipe is arranged to be in a convergent shape with a wide upper part and a narrow lower part, the outer wall of the upper part of the air inlet pipe is provided with a silencer, the air inlet pipe is made of a metal material with strong heat insulation, the air pressure of air entering the air inlet pipe is gradually increased by the aid of the air inlet pipe with the wide upper part and the narrow lower part, air is blown by the aid of the air inflow impeller, and noise of the air inlet pipe is reduced by the silencer.

Further, the end face middle part of one end of the shell, which is far away from the gas transmission port, is provided with a tailstock, a first sealing bearing is arranged in the tailstock, the first sealing bearing is connected with one end of the main shaft, which is far away from the second driving motor, the tailstock is made of metal materials with high thermal conductivity, the outer wall of the tailstock is provided with a temperature sensor, the position, which is close to the tailstock, of one side end face of the shell, which is positioned above the tailstock is welded with a water tank, condensate water is filled in the water tank, and the peripheral wall of the second sealing bearing is fixed with a condensate water pipe.

Further, the upper wall of the water tank is provided with a water filling port, the lower wall of the water tank is provided with a water draining pipe, the lower end of the water draining pipe is provided with a spray head, the lower part of the water draining pipe is provided with an electromagnetic valve, and a control wire is connected between the electromagnetic valve and the temperature sensor.

Further, a flow equalizing fan is arranged between the air conveying opening and the first flow guiding ring close to the air conveying opening by the main shaft, and the main shaft rotates to drive the flow equalizing fan to rotate, so that the gas distribution entering the flow guiding ring through the air conveying opening can be more uniform, and the stability of the blower is improved.

Further, the below of shell is provided with the base, and is provided with the shock pad between base and the shell, and the base is located the position of driving motor two below and is provided with the mount table, and driving motor two installs on the mount table, and the base upper surface is located one side that the shell was kept away from to the mount table and is provided with branch, and driving motor one is installed to the upper end of branch, and driving motor one's output shaft is connected with the pivot through shaft coupling two, and the pivot is fixed with radiator fan, and radiator fan's height and driving motor two parallel and level.

Further, the position that shell upper portion is close to the tailstock is provided with the outlet duct, and the inner wall of outlet duct is provided with pressure sensor, and the outlet duct is located the terminal top of first wheel seat that is close to the tailstock, pressure sensor survey outflow device's gaseous pressure, and the pressure of blast gas floats in a certain limit when the air-blower steady operation, judges whether the device breaks down through pressure sensor's reading, thereby the staff can in time discover the trouble of air-blower when making the air-blower work and shut down the processing, prevent because the air-blower trouble causes the loss in the operation process.

In summary, the beneficial effects in this scheme are:

1. Through the device of the impeller and the reflux ring, when gas enters the shell from the gas delivery port, the gas sequentially passes through the guide ring, the impeller and the reflux ring, flows into the guide ring of the next stage through the reflux port on the reflux ring, and repeats the previous cycle until the gas bulges out from the gas outlet pipe, the guide ring from the bulge of the impeller to the advance of the impeller of the next stage is in a convergent shape with wide front and narrow rear, so that the pressure of the bulged gas is increased, and the gas is promoted to flow to the impeller of the next stage;

Meanwhile, the windward surface of the guide ring is a cambered surface, when the gas has a trend of axial movement from radial movement of the impeller to outflow of the gas from the backflow port, the guide ring of the cambered surface can reduce energy loss generated by converting the radial movement of the gas into the axial movement, and meanwhile, the gas performs direct-current movement in the shell, so that the gas circulation channel is short, the gas flow velocity is more uniform, and the loss in the circulation process is less;

2. The multistage centrifugal blower comprises a filter screen and a shock wave soot blower, wherein the filter screen can filter impurities in the air after the external air enters an air inlet pipe, so that the impurities in the air are prevented from damaging an impeller, the service life of the device is prolonged, the shock wave soot blower cleans adhesive substances on the inner wall of the air inlet pipe, the device is prevented from being used for a long time, the impurities are adhered to the inner wall of the air inlet pipe, and the air is prevented from forming channeling on the inner wall of the air inlet pipe, so that the blowing effect is influenced;

3. When the temperature sensor detects that the temperature of the tailstock exceeds a certain value, the electromagnetic valve is controlled to be opened, condensed water in the water tank is sprayed onto the tailstock through the spray head to reduce the temperature of the first sealing bearing, meanwhile, the condensed water pipe is continuously filled with water to reduce the temperature of the second sealing bearing, and the service life and the use safety of the device are prolonged;

4. A multistage centrifugal blower is provided, through the device of driving motor I and radiator fan that sets up, when the blower long-time during operation, driving motor II is sent out to scald owing to the operation self of not stopping, high temperature damages driving motor II's part easily and leads to the device trouble, start driving motor I and radiator fan play the radiating effect to driving motor II, thereby prolonging device life and the security of operation process, simultaneously, the shock pad plays the cushioning effect, thereby prevent the air-blower at the during operation shell vibrations and make the base vibrations, thereby lead to driving motor II vibrations, lead to the main shaft to be damaged, influence the life of machine.

Drawings

FIG. 1 is a schematic view of a multistage centrifugal blower according to the present invention;

FIG. 2 is a cross-sectional view of a housing of a multistage centrifugal blower in accordance with the present invention;

FIG. 3 is a schematic view of the inside of a housing of a multistage centrifugal blower according to the present invention;

FIG. 4 is a schematic view of a condensate pipe and a second seal bearing of a multistage centrifugal blower according to the present invention;

FIG. 5 is a schematic view of the structure of a water tank and tailstock of a multistage centrifugal blower according to the present invention;

Fig. 6 is a schematic structural diagram of a wheel seat and a backflow ring of a multistage centrifugal blower according to the present invention.

In the figure: 1-shell, 2-wheel seat, 3-impeller, 4-return port, 5-main shaft, 6-guide ring, 7-air inlet, 8-outlet pipe, 9-pressure sensor, 10-water tank, 11-temperature sensor, 12-sealed bearing I, 13-tailstock, 14-shock pad, 15-base, 16-support rod, 17-mount table, 18-driving motor I, 19-radiator fan, 20-driving motor II, 21-coupler, 22-flow equalizing fan, 23-return ring, 24-silencer, 25-air inlet pipe, 26-filter screen, 27-shock wave soot blower, 28-flange, 29-nozzle, 30-air inlet, 31-sealed bearing II, 32-condensed water pipe, 33-water filling port, 34-condensed water, 35-drain pipe and 36-electromagnetic valve.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.

In the description of the present invention, it should be understood that the terms "upper," "lower," "side," "center," "midpoint," "upper," "top," "bottom," "inner," "outer," and the like indicate an orientation or a positional relationship based on that shown in the drawings, merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements in question must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.

Example 1

Referring to fig. 1-3 and 6, a multistage centrifugal blower comprises a housing 1 with a cylindrical cavity inside, a circular hole is formed in the center of one side end face of the housing 1, a second sealing bearing 31 is embedded in the circular hole, a main shaft 5 is sleeved in the second sealing bearing 31, one end of the main shaft 5, which is positioned on the housing 1, is connected with a coupler 21, the coupler 21 is connected with a second driving motor 20, a gas transmission port 30 is arranged at the position, which is positioned above the circular hole, of one side end wall of the housing 1, a gas transmission port 30 is arranged at one side end wall of the housing 1, a plurality of guide rings 6 are equidistantly welded on the inner wall of the housing 1, a gas inlet 7 is arranged in the center of the guide ring 6, a wheel seat 2 is arranged at the position, which is positioned between two adjacent guide rings 6, an impeller 3 is arranged on the outer wall of the wheel seat 2, one end, which is positioned on the inner wall of the housing 1, of the guide ring 6 and is close to the gas transmission port 30, is welded with a backflow ring 23, and a plurality of backflow ports 4 are equidistantly arranged on the backflow ring 23.

In the invention, the circumferential inner wall of the backflow ring 23 is matched with the tail end of the outer wall of the adjacent wheel seat 2 in size, and a sealing device is arranged between the circumferential inner wall of the backflow ring 23 and the tail end of the outer wall of the wheel seat 2, and the sealing device prevents gas from flowing out from a gap between the backflow ring 23 and the wheel seat 2 and prevents uneven gas flow velocity.

In the invention, an air inlet pipe 25 is welded on one side end wall of a shell 1, a flange 28 is arranged at the upper end of the air inlet pipe 25, the air inlet pipe 25 is communicated with an air delivery port 30, a filter screen 26 is clamped at the upper part of the inner wall of the air inlet pipe 25, and a shock wave soot blower 27 is arranged on the inner wall of the air inlet pipe 25.

In the invention, one side of the guide ring 6 close to the gas transmission port 30 is provided with an inward concave cambered surface, and one side of the guide ring 6 far away from the gas transmission port 30 is provided with a plane perpendicular to the side wall of the shell 1, the guide ring 6 with the cambered surface plays a role in guiding, so that gas can stably enter the gas inlet 7 of the guide ring 6 at the next stage and the impeller 3.

In the invention, the flow equalizing fan 22 is arranged between the air conveying port 30 and the first guide ring 6 close to the air conveying port 30 by the main shaft 5, and the main shaft 5 rotates to drive the flow equalizing fan 22 to rotate, so that the gas distribution entering the guide ring 6 through the air conveying port 30 can be more uniform, and the stability of the blower is improved.

In the invention, the air inlet pipe 25 is arranged in a convergent shape with a wide upper part and a narrow lower part, the silencer 24 is arranged on the outer wall of the upper part of the air inlet pipe 25, the air inlet pipe 25 is made of a metal material with strong heat insulation, the air inlet pipe 25 with the wide upper part and the narrow lower part gradually increases the pressure of air entering the air inlet pipe 25, the air is favorable for flowing into the impeller 3 for blowing, and the silencer 24 reduces the noise of the air inlet pipe 25

In the invention, the air outlet pipe 8 is arranged at the upper part of the shell 1 near the tailstock 13, the pressure sensor 9 is arranged on the inner wall of the air outlet pipe 8, the air outlet pipe 8 is positioned above the tail end of the first wheel seat 2 near the tailstock 13, the pressure sensor 9 measures the pressure of air flowing out of the device, the pressure of the blown air floats within a certain range when the blower stably works, and whether the device breaks down is judged by the reading of the pressure sensor 9, so that a worker can timely find the fault of the blower when the blower works, thereby stopping the machine, and preventing the loss in the working process caused by the fault of the blower.

Working principle: when external gas enters the air inlet pipe 25, the filter screen 26 can filter impurities in the gas, so that the impurities in the gas are prevented from damaging the impeller 3, the service life of the device is prolonged, the shock wave soot blower 27 cleans the adhesion matters on the inner wall of the air inlet pipe 25, the device is prevented from being used for a long time, the impurities are prevented from adhering on the inner wall of the air inlet pipe 25, and the air blowing effect is influenced due to the fact that the gas forms channeling on the inner wall of the air inlet pipe 25; when gas enters the shell 1 from the gas delivery port 30, the gas sequentially flows into the next-stage guide ring 6 through the guide ring 6, the impeller 3 and the backflow ring 23, and flows into the next-stage guide ring 6 through the backflow port 4 on the backflow ring 23, the previous cycle is repeated until the gas bulges out of the gas outlet pipe 8, the guide ring 6 which flows into the next-stage impeller 3 and goes forward is in a convergent shape with wide front and narrow back, the pressure of the bulged gas is increased, the gas is promoted to flow to the next-stage impeller 3, meanwhile, the windward surface of the guide ring 6 is an arc surface, when the gas has the trend of axial movement from the radial movement of the impeller 3 to the outflow of the backflow port 4, the guide ring 6 of the arc surface can reduce the energy loss generated by the conversion of the radial movement of the gas into the axial movement, meanwhile, the gas flows in the shell 1 in a direct-flow mode, the gas flow channel is short, the gas flow speed is more uniform, and the loss in the flow process is less.

Example 2

Referring to fig. 1-6, in this embodiment, compared with embodiment 1, the multistage centrifugal blower further comprises a tailstock 13 disposed in the middle of an end surface of the housing 1, which is far away from the gas transmission port 30, a first sealing bearing 12 is mounted in the tailstock 13, the first sealing bearing 12 is connected with one end of the spindle 5, which is far away from the second driving motor 20, the tailstock 13 is made of a metal material with high thermal conductivity, a temperature sensor 11 is mounted on the outer wall of the tailstock 13, a water tank 10 is welded at a position of the end surface of the housing 1, which is near the tailstock 13, above the tailstock 13, condensed water 34 is mounted in the water tank 10, and a condensation water pipe 32 is fixed on the peripheral wall of the second sealing bearing 31.

In the invention, the upper wall of the water tank 10 is provided with the water filling port 33, the lower wall of the water tank 10 is provided with the water draining pipe 35, the lower end of the water draining pipe 35 is provided with the spray head 29, the lower part of the water draining pipe 35 is provided with the electromagnetic valve 36, a controller is connected between the electromagnetic valve 36 and the temperature sensor 11, the temperature sensor 11 transmits an electric signal to the controller, when the temperature sensor 11 detects that the temperature of the tailstock 13 is too high, the controller obtains a corresponding electric signal, the electromagnetic valve 36 is controlled to be opened, water in the water tank 10 is discharged, and the tailstock 13 is cooled.

According to the invention, the base 15 is arranged below the shell 1, the shock pad 14 is arranged between the base 15 and the shell 1, the mounting table 17 is arranged at the position of the base 15 below the second driving motor 20, the second driving motor 20 is mounted on the mounting table 17, the supporting rod 16 is arranged on one side of the upper surface of the base 15, which is far away from the shell 1, of the mounting table 17, the first driving motor 18 is mounted at the upper end of the supporting rod 16, the output shaft of the first driving motor 18 is connected with the rotating shaft through the second coupling, the rotating shaft is fixedly provided with the cooling fan 19, the height of the cooling fan 19 is level with the second driving motor 20, the shock pad 14 plays a role in shock absorption, and the vibration of the shell is prevented when the blower works, so that the base 15 vibrates, the second driving motor 20 vibrates, the main shaft 5 is damaged, and the service life of the machine and the safety of the device in the operation process are affected.

Working principle: when the main shaft 5 works for a long time, high heat is generated near the first sealing bearing 12 and the second sealing bearing 31 due to friction, the high temperature has a certain influence on the performance of the sealing bearings, equipment is easy to damage, when the temperature sensor 11 detects that the temperature of the tailstock 13 exceeds a certain value, the electromagnetic valve 36 is controlled to be opened, condensed water 34 in the water tank 10 is sprayed onto the tailstock 13 through the spray head 29, so that the temperature of the first sealing bearing 12 is reduced, meanwhile, the second sealing bearing 31 is reduced due to continuous water supply in the condensed water pipe 32, and the service life and the use safety of the device are prolonged; when the blower works for a long time, the second driving motor 20 is scalded by the self-operation without stopping, the parts of the second driving motor 20 are easily damaged at high temperature to cause the device to be in fault, the first driving motor 18 and the cooling fan 19 are started to play a role in cooling the second driving motor 20, and the service life of the device is prolonged and the safety of the operation process is prolonged.

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims

1. The utility model provides a multistage centrifugal blower, includes establishes cavity for shell (1) of cylinder in, circular hole has been seted up at the side end face center of shell (1), and circular hole is embedded to be equipped with sealed bearing two (31), and sealed bearing two (31) endotheca has been connected with main shaft (5), and main shaft (5) are connected with shaft coupling (21) in the one end of shell (1), and shaft coupling (21) are connected with driving motor two (20), the position that one side end wall of shell (1) is located the top of circular hole is provided with defeated gas port (30), and one side end wall of shell (1) defeated gas port (30), and characterized in that, the center of shell (1) inner wall equidistance welding has a plurality of water conservancy diversion circle (6), and the center of water conservancy diversion circle (6) is provided with air inlet (7), and main shaft (5) are located the position between two adjacent water conservancy diversion circles (6) and are provided with wheel seat (2), and wheel seat (2) outer wall, the one end that shell (1) inner wall is located water conservancy diversion circle (6) is close to defeated gas port welding has reflux ring (23), and reflux ring (23) are provided with the circumference of a plurality of water conservancy diversion ring (4) and are mutually equal-spaced apart from each other end of end wall (2), and be provided with sealing device between the outer wall end of the circular inner wall of return ring (23) and wheel seat (2), one side that return ring (6) is close to defeated gas port (30) sets up to the cambered surface of indent, and one side that return ring (6) kept away from defeated gas port (30) sets up to the plane of perpendicular to shell (1) lateral wall, main shaft (5) are located defeated gas port (30) and are close to first return ring (6) of defeated gas port (30), are provided with flow equalizing fan (22) between first return ring (6) of defeated gas port (30), after gas gets into shell (1) from defeated gas port (30), in proper order through return ring (4) on return ring (23) inflow next stage in baffle ring (6), last circulation is repeated until gas from outlet duct (8) bulge, and baffle ring (6) that advance of impeller (3) of next stage is the front wide back narrow convergence form, make bulge gas increase, when gas from radial motion from impeller (3) has the radial direction of flow ring (4) and flow direction of return ring (3) and flow rate in the radial direction of flow ring (4) and radial motion of the shell (1) can be had, the axial motion of flow loss when the radial motion of gas from impeller (3) is had.

2. The multistage centrifugal blower according to claim 1, wherein an air inlet pipe (25) is welded on one side end wall of the housing (1), a flange (28) is arranged at the upper end of the air inlet pipe (25), the air inlet pipe (25) is communicated with the air delivery port (30), a filter screen (26) is clamped on the upper portion of the inner wall of the air inlet pipe (25), and a shock wave soot blower (27) is mounted on the inner wall of the air inlet pipe (25).

3. The multistage centrifugal blower according to claim 2, wherein the air inlet pipe (25) is provided in a convergent shape having a wide upper portion and a narrow lower portion, a muffler (24) is provided on an upper outer wall of the air inlet pipe (25), and the air inlet pipe (25) is made of a metallic material having high heat insulation.

4. The multistage centrifugal blower according to claim 1, wherein a tail seat (13) is arranged in the middle of an end face of the shell (1) far away from the gas transmission port (30), a first sealing bearing (12) is arranged in the tail seat (13), the first sealing bearing (12) is connected with one end of the main shaft (5) far away from the second driving motor (20), the tail seat (13) is made of a metal material with high heat conductivity, a temperature sensor (11) is arranged on the outer wall of the tail seat (13), a water tank (10) is welded at a position, above the tail seat (13), of one side end face of the shell (1) close to the tail seat (13), condensed water (34) is filled in the water tank (10), and a condensate water pipe (32) is fixed on the peripheral wall of the second sealing bearing (31).

5. The multistage centrifugal blower according to claim 4, wherein the upper wall of the water tank (10) is provided with a water filling port (33), the lower wall of the water tank (10) is provided with a water discharging pipe (35), the lower end of the water discharging pipe (35) is provided with a spray head (29), the lower part of the water discharging pipe (35) is provided with a solenoid valve (36), and a control wire is connected between the solenoid valve (36) and the temperature sensor (11).

6. The multistage centrifugal blower according to claim 1, wherein a base (15) is arranged below the housing (1), a shock pad (14) is arranged between the base (15) and the housing (1), a mounting table (17) is arranged at a position below the second driving motor (20) and positioned on the second driving motor (20), a supporting rod (16) is arranged on one side, far away from the housing (1), of the upper surface of the base (15) and positioned on the mounting table (17), a first driving motor (18) is arranged at the upper end of the supporting rod (16), an output shaft of the first driving motor (18) is connected with a rotating shaft through a second coupling, a cooling fan (19) is fixed on the rotating shaft, and the height of the cooling fan (19) is flush with the second driving motor (20).

7. The multistage centrifugal blower according to claim 1, wherein an air outlet pipe (8) is arranged at the upper part of the housing (1) near the tailstock (13), a pressure sensor (9) is arranged on the inner wall of the air outlet pipe (8), and the air outlet pipe (8) is arranged above the tail end of the first wheel seat (2) near the tailstock (13).