Integrated protection magnetic suspension motor and magnetic suspension vacuum pump

Abstract

The invention relates to an integrated protection magnetic suspension motor and a magnetic suspension vacuum pump, and belongs to the technical field of magnetic suspension motor protection. In the magnetic suspension motor, a front backboard is arranged at the front end of a casing, a tail end cover and a tail end cover are arranged at the rear end of the casing, the casing, the front backboard, the tail end cover and the tail end cover form an installation cavity, and a front protection bearing seat, a front radial magnetic bearing seat, a rear protection bearing seat and a rear radial magnetic bearing seat are installed in the installation cavity. And a seam and a connecting surface between the bearing seats are prevented from being exposed outside. Only one air inlet and one air outlet are formed in the machine shell, leakage points are reduced through the design of the single air inlet and the single air outlet, and protection above IP54 is achieved. Meanwhile, heat dissipation and protection of the motor are considered at the same time through the design.

Description

Technical Field

[0001] The invention relates to a magnetic levitation motor and a magnetic levitation vacuum pump with integrated protection, belonging to the technical field of magnetic levitation motor protection. Background Art

[0002] Magnetic levitation vacuum pumps use magnetic levitation bearings to achieve contactless suspension of the rotating shaft. They have significant advantages such as no oil pollution, high speed, low vibration and noise. They are widely used in semiconductors, photovoltaics, papermaking, chemical industry and other fields.

[0003] As the core of the magnetic levitation vacuum pump, the magnetic levitation motor mainly includes a rotating shaft, a stator, a front radial magnetic bearing, a rear radial magnetic bearing and an axial magnetic bearing, as well as front and rear protective bearings that serve as protection. These bearings need to be installed and positioned accurately and firmly, and the installation design of the bearing seat is crucial.

[0004] In existing magnetic levitation vacuum pump designs, bearing seats are typically manufactured as independent components and then bolted to the pump housing structure. The assembly interfaces between multiple independent bearing seats and the housing, as well as between the bearing seats themselves, create a large number of complex joints and connection surfaces. These locations are weak links in sealing, making it difficult to prevent dust, water vapor, oil mist, and even corrosive gases from invading the interior of the vacuum pump cavity through these gaps. This severely restricts the improvement of the protection level of magnetic levitation vacuum pumps (such as IP54, IP65, etc.) and limits their application in harsh industrial environments such as humid, dusty, and corrosive atmospheres. Furthermore, in existing designs, multiple heat dissipation channels or openings are often provided on the bearing seat for better heat dissipation. However, this conflicts with the requirements for improved sealing and protection level, limiting the design optimization space for achieving efficient heat dissipation while maintaining a high protection level.

[0005] Therefore, an improved magnetic levitation vacuum pump is urgently needed to significantly improve the protection level and overall heat dissipation problem. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides an integrated magnetic levitation motor with integrated protection. The front protective bearing seat, front radial magnetic bearing seat, rear protective bearing seat, and rear radial magnetic bearing seat are mounted inside the housing, preventing the joints and connecting surfaces between the bearing seats from being exposed. A single air inlet and outlet design reduces leakage points, achieving IP54 protection and exceeding that of conventional multi-air vent motors. Furthermore, a heat dissipation impeller is installed inside the magnetic levitation motor, utilizing negative pressure to direct cooling air into the motor for efficient heat dissipation.

[0007] At the same time, the present invention also provides a magnetic levitation vacuum pump.

[0008] The technical solution of the present invention is: An integrated protective magnetic levitation motor includes a housing, a front back plate is provided at the front end of the housing, a tail end seal is provided at the rear end of the housing, and the housing, the front back plate, the tail end cover and the tail end shield form an installation cavity. There is only one air inlet and one air outlet on the casing. In the installation cavity, the interior of the stator is provided with a rotating shaft, and the front end of the stator is provided with a front radial magnetic bearing seat and a front protective bearing seat from the inside to the outside. The front radial magnetic bearing seat and the front protective bearing seat are respectively provided with a front radial magnetic bearing and a front protective bearing; The rear end of the stator is provided with a rear radial magnetic bearing seat and a rear protective bearing seat from the inside to the outside. The rear radial magnetic bearing seat is respectively installed with a rear radial magnetic bearing and an axial magnetic bearing, and the rear protective bearing seat is installed with a rear protective bearing; A cooling impeller is installed at the rear end of the rotating shaft, and the cooling impeller is arranged on the outside of the rear protective bearing seat along the axial direction of the rotating shaft. A guide cover is also provided on the outside of the cooling impeller. Under the action of negative pressure, cooling air enters the installation cavity from the air inlet, passes through the cooling impeller and the first cooling air duct, and is then transmitted to the other side of the motor, and finally discharged from the air outlet to achieve cooling of the inside of the motor.

[0009] Preferably, according to the present invention, the front radial magnetic bearing seat is fixed inside the casing, the front protective bearing seat is fixed on the outside of the front radial magnetic bearing seat, and the front protective bearing seat is nested inside the front back plate.

[0010] Preferably, according to the present invention, a surface of the front back plate facing the outside of the installation cavity is provided with a plurality of sealing grooves, and a surface of the front back plate close to the front protective bearing seat is provided with a sealing groove.

[0011] Preferably, according to the present invention, a plurality of sealing grooves are provided on the surface of the front protective bearing seat facing the outside of the installation cavity, and a plurality of first ventilation holes are opened on the side wall of the front protective bearing seat surrounding the rotating shaft.

[0012] Preferably, according to the present invention, the rear radial magnetic bearing seat is fixed inside the casing, the rear protective bearing seat and the air guide cover are fixed on the outside of the rear radial magnetic bearing seat, and a first cooling air duct is enclosed between the rear protective bearing seat and the air guide cover.

[0013] Preferably, according to the present invention, the magnetic levitation motor further includes an intercooler, and the intercooler is fixed to the lower portion of the casing, so that the air inlet and the air outlet on the casing are respectively connected to the air outlet and the air inlet of the intercooler.

[0014] According to a preferred embodiment of the present invention, a water channel is further provided on the casing to ensure sufficient heat dissipation of the stator.

[0015] A magnetic levitation vacuum pump comprises the magnetic levitation motor, and a working impeller is installed at the front end of the rotating shaft. The working impeller is sheathed with a volute, which is directly fixed on the casing. A collector is provided on the outside of the volute.

[0016] Preferably, according to the present invention, the magnetic levitation vacuum pump is further provided with a pressure equalizing mechanism, and the pressure equalizing mechanism includes a pressure equalizing hole, a pressure equalizing cavity, an air guide hole and a pressure equalizing channel; a plurality of pressure equalizing holes are provided on the front back plate, and a pressure equalizing plate is provided on the inner side of the front back plate, the pressure equalizing plate and the front back plate are arranged to form a pressure equalizing cavity, air guide holes are provided on the pressure equalizing plate, and a pressure equalizing channel is also provided on the casing, and the two ends of the pressure equalizing channel are respectively connected to the air guide holes and the collector.

[0017] The beneficial effects of the present invention are: 1. This application installs the front protective bearing, front radial magnetic bearing, rear protective bearing, and rear radial magnetic bearing inside the mounting cavity, preventing the joints and connection surfaces between the bearings from being exposed. The single air inlet and single air outlet design reduces leakage points and achieves IP54 or higher protection, surpassing traditional multi-air outlet motors.

[0018] 2. In this application, the front back plate radially covers the outside of the front protective bearing seat. This axial nesting and radial covering design in the radial direction of the shaft can shorten the length of the shaft, while eliminating the deformation risk of the integral front back plate and ensuring the reliability of the front protective bearing.

[0019] 3. In this application, the volute and the front radial magnetic bearing seat are both installed based on the casing, with a coaxiality error of ≤0.05mm, to avoid the volute gravity squeezing the front protective bearing seat, thereby increasing the service life of the front protective bearing and reducing the failure rate.

[0020] 4. The magnetic levitation motor in this application utilizes a single air inlet / outlet combined with a primary cooling duct featuring a heat dissipation impeller, creating a self-circulating cooling system that significantly improves airflow compression efficiency. The motor is connected to an intercooler, effectively cooling the cooling air and ensuring effective cooling. Furthermore, a water channel is incorporated into the housing to ensure effective cooling of the stator. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural schematic diagram of a magnetic levitation motor provided in an embodiment of the present invention.

[0022] Figure 2 This is a schematic structural diagram of the front protective bearing seat provided in an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the three-dimensional structure of the front protective bearing seat provided in an embodiment of the present invention.

[0024] Figure 4 This is a schematic structural diagram of the front and back panels provided in an embodiment of the present invention.

[0025] Figure 5 This is a schematic structural diagram of a magnetic levitation vacuum pump provided in an embodiment of the present invention.

[0026] Figure 6 This is a schematic structural diagram of another magnetic levitation motor provided in an embodiment of the present invention.

[0027] Figure 7 This is a schematic structural diagram of another magnetic levitation vacuum pump provided in an embodiment of the present invention.

[0028] Figure 8 for Figure 7 A partial enlarged view of area A in the middle.

[0029] 1. Casing, 2. Tail end cover, 3. Tail end cover, 4. Air inlet, 5. Air inlet, 6. Rear radial magnetic bearing seat, 7. Collector, 8. Stator, 9. Rotating shaft, 10. Cooling impeller, 11. Working impeller, 12. Volute, 13. Front back plate, 14. Front protective bearing seat, 15. Front radial magnetic bearing seat, 16. Front radial magnetic bearing, 17. Rear radial magnetic bearing, 18. Axial magnetic bearing, 19. Air outlet, 20. First ventilation hole, 21. Sealing groove, 22. Air guide cover, 23. Second cooling air duct, 24. Air guide hole, 25. Pressure equalizing pipe, 26. Pressure equalizing plate, 27. Pressure equalizing hole, 28. Pressure equalizing channel, 29. Rear protective bearing seat, 30. First cooling air duct, 31. Water channel. DETAILED DESCRIPTION

[0030] Several embodiments of the present application will be disclosed below with diagrams to clearly and completely describe the technical solution of the present invention, which constitute a part of the present application. The drawings in the specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] It should be noted that unless the directions are defined separately, the directions such as up, down, left, and right mentioned in this document are based on the embodiments of this application. Figure 1 The directions of up, down, left, and right shown are used as the reference. If the specific posture changes, the directional indication will also change accordingly. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are simply used to distinguish different components. In addition, in various embodiments of the present disclosure, the same or similar reference numerals represent the same or similar components.

[0032] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "connection" can refer to a fixed connection, a detachable connection, or an integral connection, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0033] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] This embodiment provides a magnetic levitation motor with integrated protection, such as Figure 1 and Figure 6 As shown, it includes a housing 1, a front back plate 13 is provided at the front end of the housing 1, and a tail end seal is provided at the rear end of the housing 1. The tail end seal may include a tail end cover 2 and a tail end cover 3. The tail end cover 2 is fixed on the housing 1, and the tail end cover 3 is fixed on the tail end cover 2. The housing 1, the front back plate 13, the tail end cover 2 and the tail end cover 3 form an installation cavity. There is only one air inlet 4 and one air outlet 19 provided on the housing 1. In the installation cavity, the interior of the stator 8 is fitted with a rotating shaft 9, and the front radial magnetic bearing seat 15 and the front protective bearing seat 14 are fitted on the front end of the stator 8 from the inside to the outside. The front radial magnetic bearing seat 15 and the front protective bearing seat 14 are respectively fitted with a front radial magnetic bearing 16 and a front protective bearing; the front protective bearing is not marked in the accompanying drawings.

[0035] The rear end of the stator 8 is provided with a rear radial magnetic bearing seat 6 and a rear protective bearing seat 29 from the inside to the outside. The rear radial magnetic bearing seat 6 is internally installed with a rear radial magnetic bearing 17 and an axial magnetic bearing 18. Here, the rear radial magnetic bearing seat 6 adopts an integrated design; the rear protective bearing seat 29 is internally provided with a rear protective bearing; A heat dissipation impeller 10 is installed at the rear end of the rotating shaft 9, and the heat dissipation impeller 10 is located on the rear side of the rear protective bearing seat 29 along the axial direction of the rotating shaft. A deflector 22 is also provided on the outside of the heat dissipation impeller 10; under the action of negative pressure, the cooling air enters the installation cavity from the air inlet 4, passes through the heat dissipation impeller 10, the first cooling air duct 30, the stator 8 and the rotating shaft 9, and is then transmitted to the other side of the motor, taking away the heat of each component, and finally discharged from the air outlet 19 to achieve cooling of the inside of the motor.

[0036] The front radial magnetic bearing seat 15, the front protective bearing seat 14, the rear radial magnetic bearing seat 6 and the rear protective bearing seat 29 are arranged inside the installation cavity, and only one air inlet 4 and one air outlet 19 are arranged on the casing 1, which can provide better protection for the core components of the motor and improve the protection level of the magnetic levitation motor.

[0037] In an exemplary embodiment, Figure 1 As shown, the front radial magnetic bearing seat 15 is fixed inside the casing 1, the front protective bearing seat 14 is fixed on the outside of the front radial magnetic bearing seat 15, and the front protective bearing seat 14 is nested inside the front back plate 13, and the front back plate 13 radially covers the outside of the front protective bearing seat 14.

[0038] In the existing design, the front back plate 13 and the front protective bearing seat 14 are designed to be separated at the front and rear and are sequentially mounted on the rotating shaft 9, but this will increase the length of the rotating shaft 9 and the complexity of installation. Alternatively, the front back plate 13 and the front protective bearing seat 14 are integrated together to form an integrated back plate. Although the integrated back plate can shorten the size of the rotating shaft 9, the radius of the integrated back plate is too large and it will easily deform during operation, affecting the protective effect of the front protective bearing. In the present application, the front radial magnetic bearing seat 15 and the front back plate 13 are designed to be nested inside and outside, which can not only reduce the length of the rotating shaft 9, but also ensure that the front back plate 13 does not deform and the front protective bearing can play a role.

[0039] In an exemplary embodiment, Figure 4 As shown, the surface of the front back plate 13 facing the outside of the mounting cavity is provided with several sealing grooves 21, and the surface of the front back plate 13 near the front protective bearing seat 14 is also provided with a sealing groove 21. In magnetic levitation motor-related equipment, the sealing grooves 21 prevent wind at the front end of the motor from leaking into the mounting cavity through the gap between the front back plate 13 and the front protective bearing seat 14.

[0040] In an exemplary embodiment, Figure 2 and Figure 3 As shown, the surface of the front protective bearing seat 14 facing the outside of the mounting cavity is provided with several sealing grooves 21. Several first ventilation holes 20 are provided in the side walls of the front protective bearing seat 14 surrounding the rotating shaft 9. Air entering through the air inlet 4 dissipates heat from other components before passing through the first ventilation holes 20 into the space enclosed by the outer walls of the housing 1, the front protective bearing seat 14, and the front radial magnetic bearing 16, and finally exiting through the air outlet 19. The first ventilation holes 20 in the side walls of the front protective bearing seat 14 guide airflow evenly through the bearing area, helping to eliminate local overheating and improve temperature uniformity.

[0041] In an exemplary embodiment, Figure 1As shown, the rear radial magnetic bearing seat 6 is fixed inside the casing 1, the rear protective bearing seat 29 and the air deflector 22 are both fixed on the outside of the rear radial magnetic bearing seat 6, and a first cooling air duct 30 is enclosed between the rear protective bearing seat 29 and the air deflector 22. The cooling air output by the heat dissipation impeller 10 passes through the first cooling air duct 30, the rear protective bearing seat 29, the axial magnetic bearing 18, and the rear radial magnetic bearing 17, or passes through the first cooling air duct and the rear radial magnetic bearing seat 6, and then reaches the space where the stator 8 coils are located.

[0042] In an exemplary embodiment, Figure 1 As shown, the magnetic levitation motor also includes an intercooler, which is fixed to the lower portion of the housing 1, such that the air inlet 4 and air outlet 19 on the housing 1 are connected to the air outlet and air inlet of the intercooler, respectively. To ensure sufficient heat dissipation within the motor, air enters through the air inlet 4 on the housing 1, removes heat from the motor, passes through the air outlet 19 on the housing 1, enters the intercooler, is fully cooled in the intercooler, and then enters through the air inlet 4 on the housing 1. This cycle repeats, ensuring effective heat dissipation within the motor. The intercooler is not shown in the figure.

[0043] In an exemplary embodiment, Figure 1 As shown, a water channel 31 is also provided on the housing 1 to ensure sufficient heat dissipation of the stator 8 .

[0044] The working process of the above-mentioned magnetic levitation motor is as follows: the motor is started, and the rotating shaft 9 drives the tail end cooling impeller 10 to rotate. Under the action of negative pressure, the cooling air in the intercooler enters the installation cavity through the air inlet 4 and enters the air inlet 5 of the cooling impeller 10, and is compressed by the cooling impeller 10; the compressed cooling air is divided into two paths to dissipate heat inside the motor, part of the cooling air passes through the cooling holes on the rear radial magnetic bearing seat 6, and then enters the space where the stator 8 coil is located; the other part of the cooling air passes through the cooling holes on the rear protective bearing seat 29, the axial magnetic bearing 18, and the rear radial magnetic bearing 17, and then enters the space where the stator 8 coil is located.

[0045] The cooling air passes through the gap between the rotating shaft 9 and the stator 8, removing heat from the stator 8 and the rotating shaft 9. The air then passes through the front radial magnetic bearing 16, the first ventilation hole 20 on the front protective bearing seat 14, the cavity formed between the front radial magnetic bearing seat 15 and the housing 1, and the second cooling air duct 23 provided on the housing 1. Finally, it flows back to the intercooler through the air outlet 19 on the housing 1, thus completing the cooling cycle of the motor. The second cooling air duct 23 is connected to the air outlet 19.

[0046] On the other hand, the present invention provides a magnetic levitation vacuum pump, such as Figure 5 and Figure 7As shown, it includes the above-mentioned magnetic levitation motor, and a working impeller 11 is installed at the front end of the rotating shaft 9. The outside of the working impeller 11 is sheathed with a volute 12, which is directly fixed on the casing 1. The outside of the volute 12 is provided with a collector 7.

[0047] The radial magnetic bearing seat is fixed inside the casing 1, and the volute 12 is also fixed on the casing 1, so that the front radial magnetic bearing seat 15 and the volute 12 are both based on the casing 1, which can better ensure the coaxiality of the volute 12 and the front radial magnetic bearing stator; and the volute 12 has a large mass. Fixing the volute 12 on the casing 1 can prevent the volute 12 from causing extrusion deformation to the front protective bearing seat 14, so that the front protective bearing can better play a protective role on the rotating shaft 9.

[0048] In an exemplary embodiment, Figure 7 and Figure 8 As shown, the magnetic levitation vacuum pump is also provided with a pressure equalizing mechanism, which includes a pressure equalizing hole 27, a pressure equalizing cavity, an air guide hole 24, and a pressure equalizing channel 28. A plurality of pressure equalizing holes 27 are provided on the front back plate 13, and a pressure equalizing plate 26 is provided on the inner side of the front back plate 13. The pressure equalizing plate 26 and the front back plate 13 form a pressure equalizing cavity. The pressure equalizing plate 26 is provided with an air guide hole 24. The casing is also provided with a pressure equalizing channel 28. The two ends of the pressure equalizing channel 28 are respectively connected to the air guide hole 24 and the collector 7. When the magnetic levitation vacuum pump is working, the small end of the working impeller 11 is under negative pressure, which will attract the rotating shaft to deflect toward the volute, connecting the pressure equalizing channel 28 with the collector 7. Under the action of the negative pressure of the collector 7, the pressure equalization effect is achieved on the front and back of the working impeller 11, reducing the axial deviation of the rotating shaft 9 toward the volute 12.

[0049] In an exemplary embodiment, Figure 8 As shown, a pressure equalizing pipe 25 is provided at the outlet of the pressure equalizing channel 28, and the other end of the pressure equalizing pipe 25 is connected to the collector 7. The pressure equalizing pipe 25 is fixed to the outside of the casing to play a role in guiding flow.

[0050] The foregoing description shows and describes preferred embodiments of the present application. However, as previously mentioned, it should be understood that the present application is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present application may be used in various other combinations, modifications, and environments, and may be modified within the contemplation of the present invention through the teachings above or through techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present application shall be within the scope of protection of the appended claims.

Claims

1. A magnetic levitation motor with integrated protection, characterized in that: The invention comprises a casing, a front back plate is provided at the front end of the casing, a tail end seal is provided at the rear end of the casing, and the casing, the front back plate, the tail end cover and the tail end cover form an installation cavity; only one air inlet and one air outlet are provided on the casing; in the installation cavity, a rotating shaft is provided inside the stator, and a front radial magnetic bearing seat and a front protective bearing seat are provided at the front end of the stator from the inside to the outside, and a front radial magnetic bearing seat and a front protective bearing seat are provided inside the front radial magnetic bearing seat and the front protective bearing seat respectively; a rear radial magnetic bearing seat and a rear protective bearing seat are provided at the rear end of the stator from the inside to the outside The rear radial magnetic bearing seat is respectively installed with the rear radial magnetic bearing and the axial magnetic bearing inside the rear protective bearing seat, and the rear protective bearing is installed inside the rear protective bearing seat; a heat dissipation impeller is installed at the rear end of the rotating shaft, and the heat dissipation impeller is arranged on the outside of the rear protective bearing seat along the axial direction of the rotating shaft, and a guide cover is also provided on the outside of the heat dissipation impeller; under the action of negative pressure, the cooling air enters the installation cavity from the air inlet, passes through the heat dissipation impeller and the first cooling air duct, and is then transmitted to the other side of the motor, and finally discharged from the air outlet to realize the cooling of the inside of the motor.

2. The integrated protection magnetic levitation motor according to claim 1, characterized in that: The front radial magnetic bearing seat is fixed inside the casing, the front protection bearing seat is fixed on the outside of the front radial magnetic bearing seat, and the front protection bearing seat is nested inside the front back plate.

3. The integrated protection magnetic levitation motor according to claim 2, characterized in that: A plurality of sealing grooves are provided on the surface of the front back plate facing the outside of the installation cavity, and a sealing groove is provided on the surface of the front back plate close to the front protective bearing seat.

4. The integrated protection magnetic levitation motor according to claim 1, characterized in that: A plurality of sealing grooves are provided on the surface of the front protective bearing seat facing the outside of the installation cavity, and a plurality of first ventilation holes are opened on the side wall of the front protective bearing seat surrounding the rotating shaft.

5. The integrated protection magnetic levitation motor according to claim 1, characterized in that: The rear radial magnetic bearing seat is fixed inside the casing, the rear protective bearing seat and the air guide cover are fixed on the outside of the rear radial magnetic bearing seat, and a first cooling air duct is formed between the rear protective bearing seat and the air guide cover.

6. The integrated protection magnetic levitation motor according to claim 1, characterized in that: The magnetic levitation motor further includes an intercooler, and the intercooler is fixed to the lower portion of the casing so that the air inlet and the air outlet on the casing are respectively connected to the air outlet and the air inlet of the intercooler.

7. The integrated protection magnetic levitation motor according to claim 1, characterized in that: A water channel is also provided on the casing.

8. A magnetic levitation vacuum pump, characterized in that: The magnetic levitation motor comprises the magnetic levitation motor according to any one of claims 1 to 7, and a working impeller is installed at the front end of the rotating shaft, a volute is sheathed on the outside of the working impeller, the volute is directly fixed on the casing, and a collector is arranged on the outside of the volute.

9. The magnetic levitation vacuum pump according to claim 8, characterized in that: The magnetic levitation vacuum pump is also provided with a pressure equalizing mechanism, which includes a pressure equalizing hole, a pressure equalizing cavity, an air guide hole and a pressure equalizing channel; a plurality of pressure equalizing holes are provided on the front back plate, a pressure equalizing plate is provided on the inner side of the front back plate, the pressure equalizing plate and the front back plate are arranged to form a pressure equalizing cavity, an air guide hole is provided on the pressure equalizing plate, and a pressure equalizing channel is also provided on the casing, and the two ends of the pressure equalizing channel are respectively connected to the air guide hole and the collector.

Images