Integrated protective magnetic suspension motor and magnetic suspension vacuum pump

Abstract

The application relates to a magnetically suspended motor and a magnetically suspended vacuum pump with integrated protection, and belongs to the technical field of magnetically suspended motor protection. In the magnetically suspended motor, the front end of a motor shell is provided with a front back plate, the rear end of the motor shell is provided with a tail end cover and a tail end cover, and the motor shell, the front back plate, the tail end cover and the tail end cover form a mounting cavity. The front protection bearing seat, the front radial magnetic bearing seat, the rear protection bearing seat and the rear radial magnetic bearing seat are mounted in the interior of the mounting cavity, so that the joints and connecting surfaces between the bearing seats are prevented from being exposed to the outside. Only one air inlet and one air outlet are arranged on the motor shell, the single air inlet and air outlet design reduces the leakage points, and the protection of IP54 or above is realized. Meanwhile, the design of the application simultaneously considers the heat dissipation and protection of the motor.

Description

TECHNICAL FIELD

[0001] The application relates to a magnetic suspension motor and a magnetic suspension vacuum pump with integrated protection. BACKGROUND

[0002] The magnetic suspension vacuum pump realizes contactless suspension of a rotating shaft by using a magnetic suspension bearing, has the advantages of no oil pollution, high rotating speed, low vibration and noise, and is widely applied to the fields of semiconductors, photovoltaics, papermaking and chemical industry.

[0003] The magnetic suspension motor, as the core of the magnetic suspension vacuum pump, mainly comprises a rotating shaft, a stator, a front radial magnetic bearing, a rear radial magnetic bearing and an axial magnetic bearing, and front and rear protective bearings for protection, and the bearings need to be accurately and stably installed and positioned, and the installation design of the bearing seats is crucial.

[0004] In the existing design of the magnetic suspension vacuum pump, the bearing seats are usually manufactured as independent components and then are respectively installed on the shell structure of the pump by means of bolt connection. The assembly interfaces between the multiple independent bearing seats and the shell and between the bearing seats form a large number of complex joints and connecting surfaces. These positions are weak links of sealing, and it is difficult to prevent dust, water vapor, oil mist and even corrosive gas from invading the inside of the vacuum pump cavity through the gaps. This seriously restricts the improvement of the protection grade (such as IP54, IP65, etc.) of the magnetic suspension vacuum pump and limits the application of the magnetic suspension vacuum pump in harsh industrial environments such as humidity, dust and corrosive atmosphere. In addition, in the existing design, multiple heat dissipation channels or openings are often provided on the bearing seats for better heat dissipation, but this conflicts with the requirement of improving the sealing and protection grade, so that the design optimization space for realizing high-efficiency heat dissipation under the premise of high protection grade is limited.

[0005] Therefore, an improved magnetic suspension vacuum pump is urgently needed to significantly improve the protection grade and overall heat dissipation problem. SUMMARY

[0006] In view of the deficiencies of the prior art, the application provides a magnetic suspension motor with integrated protection, which installs a front protective bearing seat, a front radial magnetic bearing seat, a rear protective bearing seat and a rear radial magnetic bearing seat in the inside of a shell, so as to avoid the joints and connecting surfaces between the bearing seats from being exposed to the outside. A single air inlet and a single air outlet are adopted to reduce the leakage points and realize protection above IP54, which is superior to the traditional multi-air-port motor. Meanwhile, a heat dissipation impeller is arranged in the magnetic suspension motor to utilize negative pressure to guide cooling air to the inside of the motor for sufficient heat dissipation.

[0007] Meanwhile, the application also provides a magnetic suspension vacuum pump.

[0008] The technical scheme of the application is as follows:

[0009] The integrated protective magnetic suspension motor comprises a shell, a front back plate arranged at the front end of the shell, and a tail end sealing element arranged at the rear end of the shell, wherein the shell, the front back plate, the tail end cover and the tail end cover form an installation cavity,

[0010] Only one air inlet and one air outlet are arranged on the shell,

[0011] In the installation cavity, the inside of the stator is sleeved with a rotating shaft, the front end of the stator is sleeved from inside to outside with a front radial magnetic bearing seat and a front protection bearing seat, and the inside of the front radial magnetic bearing seat and the front protection bearing seat is respectively arranged with a front radial magnetic bearing and a front protection bearing;

[0012] The rear end of the stator is arranged from inside to outside with a rear radial magnetic bearing seat and a rear protection bearing seat, the inside of the rear radial magnetic bearing seat is respectively arranged with a rear radial magnetic bearing and an axial magnetic bearing, and the inside of the rear protection bearing seat is arranged with a rear protection bearing;

[0013] The rear end of the rotating shaft is arranged with a cooling impeller, the cooling impeller is arranged on the outside of the rear protection bearing seat along the axial direction of the rotating shaft, and a flow guide cover is further arranged 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, is then transmitted to the other side of the motor, and is finally discharged from the air outlet, thereby realizing the cooling of the inside of the motor.

[0014] According to the application, the front radial magnetic bearing seat is fixed to the inside of the shell, the front protection bearing seat is fixed to the outside of the front radial magnetic bearing seat, and the front protection bearing seat is nested in the inside of the front back plate.

[0015] According to the application, the surface of the front back plate facing the outside of the installation cavity is arranged with a plurality of sealing grooves, and the surface of the front back plate close to the front protection bearing seat is arranged with a sealing groove.

[0016] According to the application, the surface of the front protection bearing seat facing the outside of the installation cavity is arranged with a plurality of sealing grooves, and a plurality of first ventilation holes are formed in the side wall of the front protection bearing seat surrounding the rotating shaft.

[0017] According to the application, the rear radial magnetic bearing seat is fixed to the inside of the shell, the rear protection bearing seat and the flow guide cover are both fixed to the outside of the rear radial magnetic bearing seat, and the rear protection bearing seat and the flow guide cover form the first cooling air duct.

[0018] According to the application, the magnetic suspension motor further comprises an intercooler, and the intercooler is fixed to the lower part of the shell, so that the air inlet and the air outlet on the shell are respectively connected with the air outlet and the air inlet of the intercooler.

[0019] According to the application, a water channel is further formed in the shell, thereby ensuring sufficient heat dissipation of the stator.

[0020] A magnetic levitation vacuum pump includes the aforementioned magnetic levitation motor, and a working impeller is installed at the front end of the rotating shaft. A volute is fitted around the working impeller and is directly fixed to the housing. A collector is provided on the outer side of the volute.

[0021] According to a preferred embodiment of the present invention, the magnetic levitation vacuum pump is further provided with a pressure equalization mechanism, which includes pressure equalization holes, pressure equalization chamber, air guide holes, and pressure equalization channels; a plurality of pressure equalization holes are provided on the front back plate, and a pressure equalization plate is provided on the inner side of the front back plate, the pressure equalization plate and the front back plate forming a pressure equalization chamber, an air guide hole is provided on the pressure equalization plate, and a pressure equalization channel is also provided on the housing, the two ends of the pressure equalization channel being connected to the air guide hole and the collector, respectively.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This application mounts the front protective bearing housing, the front radial magnetic bearing housing, the rear protective bearing housing, and the rear radial magnetic bearing housing inside the mounting cavity, preventing the joints and connecting surfaces between the bearing housings from being exposed. The single air inlet and single air outlet design reduces leakage points and achieves IP54 or higher protection, which is superior to traditional multi-outlet motors.

[0024] 2. In this application, the front backplate radially covers the outside of the front protective bearing housing. This axial nesting and radial covering design in the radial direction of the shaft can shorten the shaft length, while eliminating the risk of deformation of the integral front backplate and ensuring the reliability of the front protective bearing.

[0025] 3. In this application, both the volute and the front radial magnetic bearing housing are installed with the housing as the mounting reference, and the coaxiality error is ≤0.05mm. This avoids the volute's gravity squeezing the front protective bearing housing, improves the service life of the front protective bearing, and reduces the failure rate.

[0026] 4. In this application, the magnetic levitation motor adopts a single inlet / outlet air duct combined with a heat dissipation impeller to form a self-circulating cooling system, which greatly improves the airflow compression efficiency. The motor is connected to the intercooler, which can fully cool the cooling air and ensure the air cooling effect. At the same time, water channels are set on the casing to ensure the cooling effect on the stator. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a magnetic levitation motor provided in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the front protective bearing housing provided in an embodiment of the present invention.

[0029] Figure 3 This is a three-dimensional structural diagram of the front protective bearing housing provided in an embodiment of the present invention.

[0030] Figure 4A structural schematic diagram of a front back plate provided for an embodiment in the present application.

[0031] Figure 5 A structural schematic diagram of a magnetic suspension vacuum pump provided for an embodiment in the present application.

[0032] Figure 6 A structural schematic diagram of another magnetic suspension motor provided for an embodiment in the present application.

[0033] Figure 7 A structural schematic diagram of another magnetic suspension vacuum pump provided for an embodiment in the present application.

[0034] Figure 8 A structural schematic diagram of a magnetic suspension motor provided for an embodiment in the present application. Figure 7 A local enlarged view of area A in the middle.

[0035] 1, housing, 2, tail end cover, 3, tail end cover, 4, air inlet, 5, air inlet, 6, rear radial magnetic bearing seat, 7, current collector, 8, stator, 9, rotating shaft, 10, heat dissipation impeller, 11, working impeller, 12, volute, 13, front back plate, 14, front protection 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, fairing, 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 protection bearing seat, 30, first cooling air duct, 31, water channel. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be described below in the drawings to clearly and completely describe the embodiments of the present application, which form a part of the present application. The drawings are used to provide further understanding of the present application, and the illustrative embodiments and descriptions are used to explain the present application and do not constitute an improper limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] It should be noted that, unless otherwise defined, the up, down, left, right and other directions referred to in this article are based on the up, down, left, right and other directions shown in the embodiments of the present application. If the specific posture changes, the directional indication also changes accordingly. The "first", "second" and similar words used in the present application do not represent any order, quantity or importance, but are used to distinguish different components. In addition, in various embodiments of the present application, the same or similar reference numerals represent the same or similar components. Figure 1

[0038] ​In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation" and the like shall be understood in a broad sense, for example, "connection" can be fixed connection, or detachable connection, or integral, unless otherwise explicitly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0039] In addition, the technical solutions among various embodiments of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it shall be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0040] The present embodiment provides a kind of integrated protection magnetic suspension motor, as shown in Figure 1 And Figure 6 As shown, it includes shell 1, the front end of shell 1 is provided with front backboard 13, the rear end of shell 1 is provided with tail end sealing element, tail end sealing element can include tail end cover 2 and tail end cover 3, tail end cover 2 is fixed on shell 1, tail end cover 3 is fixed on tail end cover 2, shell 1, front backboard 13, tail end cover 2 and tail end cover 3 form installation cavity,

[0041] Only one air inlet 4 and one air outlet 19 are provided on shell 1,

[0042] In installation cavity, the inside of stator 8 is sleeved with rotating shaft 9, the front end of stator 8 is sleeved from inside to outside and is provided with front radial magnetic bearing seat 15 and front protection bearing seat 14, the inside of front radial magnetic bearing seat 15 and front protection bearing seat 14 is respectively installed with front radial magnetic bearing 16 and front protection bearing;Front protection bearing is not marked in the drawing.

[0043] The rear end of stator 8 is provided with rear radial magnetic bearing seat 6 and rear protection bearing seat 29 from inside to outside, the inside of rear radial magnetic bearing seat 6 is installed with rear radial magnetic bearing 17 and axial magnetic bearing 18, here rear radial magnetic bearing seat 6 adopts integrated design;The inside of rear protection bearing seat 29 is provided with rear protection bearing;

[0044] The rear end of rotating shaft 9 is installed with heat dissipation impeller 10, and heat dissipation impeller 10 is located on the rear side of rear protection bearing seat 29 along the axial direction of rotating shaft, and flow guide cover 22 is further provided outside heat dissipation impeller 10;Under the action of negative pressure, cooling air enters installation cavity from air inlet 4, passes through heat dissipation impeller 10, first cooling air duct 30, stator 8 and rotating shaft 9, and then is transmitted to the other side of motor, carries away the heat of each component, and finally is discharged from air outlet 19, to realize the cooling of the inside of motor.

[0045] 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 mounting cavity, and only one air inlet 4 and one air outlet 19 are arranged on the shell 1, so that the core components of the motor can be better protected, and the protection level of the magnetic suspension motor is improved.

[0046] In one example embodiment, as shown in Figure 1 The front radial magnetic bearing seat 15 is fixed inside the shell 1, the front protective bearing seat 14 is fixed outside 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.

[0047] In the existing design, the front back plate 13 and the front protective bearing seat 14 are designed to be separated front and rear and are sequentially fitted on the rotating shaft 9, but this increases 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 designed to be integrated into an integrated back plate, which can shorten the size of the rotating shaft 9, but the radius of the integrated back plate is too large and can easily deform during operation, affecting the protection function 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 not only reduces the length of the rotating shaft 9, but also ensures that the front back plate 13 does not deform and the front protective bearing functions.

[0048] In one example embodiment, as shown in Figure 4 The face of the front back plate 13 facing the outside of the mounting cavity is provided with a plurality of sealing grooves 21, and the face of the front back plate 13 close to the front protective bearing seat 14 is provided with a sealing groove 21. In the magnetic suspension motor related equipment, the sealing groove 21 can prevent the air 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.

[0049] In one example embodiment, as shown in Figure 2 and Figure 3 The face of the front protective bearing seat 14 facing the outside of the mounting cavity is provided with a plurality of sealing grooves 21, and a plurality of first ventilation holes 20 are formed in the side wall of the front protective bearing seat 14 surrounding the rotating shaft 9. After the air entering through the air inlet 4 is cooled by other components, it finally enters the space surrounded by the outer wall of the shell 1, the front protective bearing seat 14 and the front radial magnetic bearing 16 through the first ventilation hole 20, and is finally discharged through the air outlet 19. The first ventilation hole 20 in the side wall of the front protective bearing seat 14 guides the airflow to flow evenly through the bearing area, which is conducive to eliminating local overheating and improving temperature uniformity.

[0050] In one example embodiment, as shown in Figure 1As shown, the rear radial magnetic bearing seat 6 is fixed inside the casing 1, the rear protective bearing seat 29 and the fairing 22 are both fixed outside the rear radial magnetic bearing seat 6, and the first cooling air channel 30 is formed between the rear protective bearing seat 29 and the fairing 22. The cooling air output by the heat dissipation impeller 10 passes through the first cooling air channel 30, the rear protective bearing seat 29, the axial magnetic bearing 18, the rear radial magnetic bearing 17, or passes through the first cooling air channel, the rear radial magnetic bearing seat 6, and then reaches the space where the stator 8 wire package is located.

[0051] In an exemplary embodiment, as shown in Figure 1 The magnetic levitation motor further comprises an intercooler, and the intercooler is fixed at the lower part of the casing 1, so that the air inlet 4 and the air outlet 19 on the casing 1 are in communication with the air outlet and the air inlet of the intercooler, respectively. In order to ensure sufficient heat dissipation of the motor interior, the gas enters the casing 1 through the air inlet 4, carries away the heat of the motor interior, enters the intercooler through the air outlet 19 on the casing 1, is sufficiently cooled in the intercooler, and then enters through the air inlet 4 on the casing 1, and so on, so as to ensure the heat dissipation effect of the motor interior. The intercooler is not marked in the drawings.

[0052] In an exemplary embodiment, as shown in Figure 1 The casing 1 is further provided with a water channel 31, so as to ensure sufficient heat dissipation of the stator 8.

[0053] The working process of the magnetic levitation motor is as follows: the motor is started, the shaft 9 drives the tail heat dissipation impeller 10 to rotate, and 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 heat dissipation impeller 10, and is compressed by the heat dissipation impeller 10; the compressed cooling air is divided into two paths to dissipate heat in the motor interior, a part of the cooling air passes through the heat dissipation holes on the rear radial magnetic bearing seat 6, and then enters the space where the stator 8 wire package is located; the other part of the cooling air passes through the heat dissipation 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 wire package is located.

[0054] The cooling air carries away the heat of the stator 8 and the shaft 9 through the gap between the shaft 9 and the stator 8, then passes through the first air vent 20 on the front protective bearing seat 14, the cavity formed between the front radial magnetic bearing seat 15 and the casing 1, and the second cooling air channel 23 provided on the casing 1, and finally returns to the intercooler through the air outlet 19 on the casing 1, thereby completing the cooling cycle of the motor by the first cooling air. The second cooling air channel 23 is in communication with the air outlet 19.

[0055] On the other hand, the present application provides a magnetic levitation vacuum pump, as shown in Figure 5 and Figure 7As shown, including the above-mentioned magnetic suspension motor, and the front end of the rotating shaft 9 is installed with the working impeller 11, the outside of the working impeller 11 is sleeved with the volute 12, the volute 12 is directly fixed on the casing 1, and the outside of the volute 12 is provided with the current collector 7.

[0056] The radial magnetic bearing seat is fixed in the inside of 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 referenced to the casing 1, which can better guarantee the coaxiality of the volute 12 and the front radial magnetic bearing stator; and the mass of the volute 12 is larger, and the volute 12 is fixed on the casing 1, which can avoid the extrusion deformation of the volute 12 to the front protection bearing seat 14, so that the front protection bearing can better play a protection role on the rotating shaft 9.

[0057] In an example embodiment, as shown in Figure 7 and Figure 8 As shown, the magnetic suspension vacuum pump is also provided with an equalizing mechanism, the equalizing mechanism includes equalizing holes 27, an equalizing cavity, gas guide holes 24 and an equalizing channel 28; a plurality of equalizing holes 27 are arranged on the front back plate 13, the inside of the front back plate 13 is provided with an equalizing plate 26, the equalizing plate 26 and the front back plate 13 surround to form an equalizing cavity, the equalizing plate 26 is provided with gas guide holes 24, and the casing is also provided with an equalizing channel 28, both ends of the equalizing channel 28 are respectively communicated with the gas guide holes 24 and the current collector 7. When the magnetic suspension vacuum pump works, the small end of the working impeller 11 is negative pressure, which can attract the rotating shaft to deviate towards the volute, and the equalizing channel 28 is communicated with the current collector 7, and under the negative pressure of the current collector 7, the front and back of the working impeller 11 are equalized, which reduces the axial deviation of the rotating shaft 9 to the volute 12.

[0058] In an example embodiment, as shown in Figure 8 The equalizing channel 28 is provided with an equalizing pipe 25 at the gas outlet, and the other end of the equalizing pipe 25 is communicated with the current collector 7. The equalizing pipe 25 is fixed on the outside of the casing and plays a role of guiding flow.

[0059] The above description shows and describes the preferred embodiments of the present application, but as previously mentioned, it should be understood that the present application is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, and can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept disclosed herein, by the above-mentioned teaching or related technical or knowledge. The modifications and changes made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the claims appended to the present application.

Claims

1. A magnetically levitated vacuum pump with integrated protection, characterized in that, The device includes a housing, with a front back panel at the front end and a tail seal at the rear end. The housing, front back panel, and tail seal form a sealed mounting cavity. Only one air inlet and one air outlet are provided on the housing. Inside the mounting cavity, a rotating shaft is installed inside the stator, a working impeller is installed at the front end of the rotating shaft, a volute is installed outside the working impeller, the volute is directly fixed to the housing, and a collector is provided on the outside of the volute. The front end of the stator is fitted with a front radial magnetic bearing housing and a front protective bearing housing from the inside to the outside. The front radial magnetic bearing housing and the front protective bearing housing are respectively installed inside the front radial magnetic bearing housing and the front protective bearing housing. The front radial magnetic bearing housing is fixed inside the housing, and the front protective bearing housing is fixed outside the front radial magnetic bearing housing. The front protective bearing housing is nested inside the front back plate in the radial direction of the rotor. Several first ventilation holes are opened on the side wall of the front protective bearing housing surrounding the shaft. The stator has a rear radial magnetic bearing housing and a rear protective bearing housing arranged from the inside to the outside at the rear end. The rear radial magnetic bearing housing is equipped with a rear radial magnetic bearing and an axial magnetic bearing, respectively. The rear protective bearing housing is equipped with a rear protective bearing. A heat dissipation impeller is installed at the rear end of the shaft, and the heat dissipation impeller is arranged on the outside of the rear protective bearing housing along the shaft axis. A guide shroud is also provided on the outside of the heat dissipation impeller. The magnetic levitation vacuum pump also includes an intercooler, which is fixed to the lower part of the housing, so that the air inlet and outlet on the housing are connected to the air outlet and air inlet of the intercooler, respectively. Under negative pressure, cooling air enters the mounting cavity through 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. It passes through the front radial magnetic bearing, the first ventilation hole on the front protective bearing seat, the cavity formed between the front radial magnetic bearing seat and the housing, and the second cooling air duct opened on the housing. Finally, it flows back to the intercooler through the air outlet on the housing, forming a closed cooling cycle.

2. The integrated protective magnetic levitation vacuum pump according to claim 1, characterized in that, The front backplate has several sealing grooves on the side facing the outside of the mounting cavity, and the front backplate has sealing grooves on the side near the front protective bearing seat.

3. The integrated protective magnetic levitation vacuum pump according to claim 1, characterized in that, The front protective bearing housing has several sealing grooves on the surface facing the outside of the mounting cavity.

4. The integrated protective magnetic levitation vacuum pump according to claim 1, characterized in that, The rear radial magnetic bearing housing is fixed inside the housing, while the rear protective bearing housing and the air guide are both fixed outside the rear radial magnetic bearing housing, and the rear protective bearing housing and the air guide are arranged to form the first cooling air duct.

5. The integrated protective magnetic levitation vacuum pump according to claim 1, characterized in that, Water channels are also provided on the casing.

6. The integrated protective magnetic levitation vacuum pump according to claim 1, characterized in that, The magnetic levitation vacuum pump is also equipped with a pressure equalization mechanism, which includes pressure equalization holes, pressure equalization chambers, air guide holes, and pressure equalization channels. Several pressure equalization holes are provided on the front back plate, and a pressure equalization plate is provided on the inner side of the front back plate. The pressure equalization plate and the front back plate form a pressure equalization chamber. Air guide holes are provided on the pressure equalization plate, and a pressure equalization channel is also provided on the housing. The two ends of the pressure equalization channel are connected to the air guide holes and the collector, respectively.

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