Air door actuator of rail transit fresh air system

Abstract

The utility model relates to the technical field of rail transit fresh air systems, in particular to an air door actuator of a rail transit fresh air system, which comprises a mounting bottom plate, an air door plate, a support frame, a lifting assembly and a driving assembly, the driving assembly is mounted on the support frame and comprises a rotating shaft, a rotor iron core, magnetic steel and a stator, the rotating shaft is a hollow reducing shaft, and the rotor iron core is arranged on the rotating shaft. The rotor core comprises a large-diameter section and a small-diameter section, the rotor core is mounted at the upper part of the large-diameter section, a circle of cylindrical holes are uniformly formed in the bottom surface of the large-diameter section, magnetic steel and a stator are sequentially arranged outside the rotor core, and a brake is mounted at the upper part of the small-diameter section; the lifting assembly is provided with a ball screw and a lead screw nut, the lead screw nut is installed on the ball screw and fixed to the bottom face of the large-diameter section, the upper portion of the ball screw extends into the hollow portion of the rotating shaft, the lower end of the ball screw is connected with a guide plate, and the guide plate is fixed to the middle of the top of the air door plate. The structure is more compact, the design is more reasonable, the requirement for light weight of rail transit is met, and the waterproof and dustproof requirements can be met.

Description

Technical Field

[0001] The utility model relates to the technical field of rail transit fresh air systems, in particular to a damper actuator of a rail transit fresh air system. Background Art

[0002] When the train enters the tunnel, due to the compressibility of the air and the space for the lateral and upward flow of the air limited by the walls of the train and the tunnel, the air close to the front of the train is compressed and flows forward with the train, causing the air pressure in front of the train to suddenly increase, generating a compression wave, and the other part of the air displaced by the train flows to the rear of the train through the annular space. As the train enters the tunnel further, the length of the annular space gradually increases, causing the air pressure in the tunnel space in front of the train to continue to increase, that is, the intensity of the compression wave continues to increase until the entire train enters the tunnel. The pressure wave propagates forward at the speed of sound, the air velocity in front of the pressure wave is zero, and the air behind the pressure wave flows forward with the train at a certain velocity. After the pressure wave propagates to the exit, part of it is reflected back in the form of an expansion wave, and the other part is transmitted out of the tunnel exit in the form of a micro-pressure wave.

[0003] When the pressure difference between the inside and outside of the car exceeds a certain value, the train pressure protection system is activated, and the pressure control device installed in the train electrical cabinet controls all the actions of the intermediate relays, thereby controlling the action of the pressure wave protection valves installed at the fresh air inlet and exhaust air outlet of each carriage, closing the fresh air inlet and exhaust air outlet to block the pressure waves outside the car from entering the car. At this time, the air-conditioning system operates in full return air mode.

[0004] Most of the existing pressure wave protection (protection) devices / pressure wave air valves use cylinders to drive the damper plates to open and close (for example: patents with announcement numbers CN217804719U, CN213862229U, and CN217683499U). The cylinder output motion stability is poor, and the transmission accuracy is not high. There is a delay in the opening and closing of the damper plates, and it is not convenient to accurately control the opening of the damper plates.

[0005] There are also some that use motors and transmission components to drive the damper plate to open and close. For example, the patent with announcement number CN216951906U drives the cam to rotate through the motor, and the cam drives the adjustment arm to move, thereby realizing the opening and closing of the damper plate. The structure of the cam and the adjustment arm is also not stable under high air pressure. Another example is the patent with announcement number CN210554822U, which drives the meshing bevel gear through the motor and then drives the rotating rod to rotate, thereby realizing the opening and closing of the damper plate (connected to the slider, moving along the guide rail), which can control the opening of the damper plate more accurately, but the meshing bevel gear increases the installation space of the entire pressure wave air valve, making it difficult to maintain in the later stage. In response to this patent, a rail transit vehicle air conditioning pressure wave protection device was proposed in the previous application. The motor drives the drive shaft to rotate, which in turn drives the connection block to rotate, so that the drive rod rotates, and then drives the linear guide bearing to move with the damper plate, which simplifies the number of parts, solves certain noise problems, and makes the structure more compact. However, the air outside the car contains dust and a certain amount of humidity, which will affect the transmission effect of the transmission parts. This type of motor is installed on the side, which not only ensures the convenience of the side motor installation, the installation accuracy of the transmission components, but also the convenience of the power box and the control box. With the requirement of lightweight trains, it is necessary to further ensure the compact structure and the convenience of maintenance. Utility Model Content

[0006] The technical problem to be solved by the utility model is to overcome the deficiencies in the prior art and provide a damper actuator for a rail transit fresh air system.

[0007] The technical solution adopted by the utility model to solve its technical problems is: a damper actuator of a rail transit fresh air system, comprising an installation base plate, a damper plate, a support frame, a lifting assembly and a driving assembly for driving the lifting assembly to move, the driving assembly is installed on the support frame, the driving assembly comprises a rotating shaft, a rotor core, a magnetic steel and a stator, the rotating shaft is a hollow variable diameter shaft, which comprises a large diameter section and a small diameter section, the rotor core is installed on the upper part of the large diameter section, a circle of cylindrical holes is evenly opened on the bottom surface of the large diameter section, magnetic steel and stator are sequentially arranged outside the rotor core, and a brake is installed on the upper part of the small diameter section; the lifting assembly has a ball screw and a screw nut, the screw nut is installed on the ball screw and fixed on the bottom surface of the large diameter section, the upper part of the ball screw extends into the hollow part of the rotating shaft, the lower end of the ball screw is connected to the guide plate, and the guide plate is fixed to the middle of the top of the damper plate.

[0008] Furthermore, the drive assembly has a cover, which includes a shell, an upper cover and a lower cover. The shell has a partition in the upper part, and a first through hole is opened in the middle of the partition for the small diameter section of the rotating shaft to pass through. An upper bearing with an interference fit with the rotating shaft is provided on the inner wall of the first through hole, and the brake is arranged between the upper cover and the partition.

[0009] Furthermore, a second through hole is opened in the middle of the lower cover for the large diameter section of the rotating shaft to pass through, and the second through hole is a variable diameter hole, which includes a large diameter portion and a small diameter portion. A lower bearing that is interference fit with the rotating shaft is provided on the inner wall of the large diameter portion, and the edge of the small diameter portion extends downward to form a ring edge that is clearance fit with the screw nut.

[0010] Furthermore, a flexible waterproof cover is arranged between the lower cover and the guide plate, and the waterproof cover is in a tower-shaped structure, and an upper connecting edge and a lower connecting edge are arranged on the upper and lower edges thereof respectively.

[0011] Furthermore, a ring groove is provided on the outer side of the ring edge of the bottom surface of the lower cover, a waterproof upper pressing plate connected to the upper connecting edge is provided in the ring groove, and a waterproof lower pressing plate connected to the lower connecting edge is provided on the upper surface of the guide plate.

[0012] Furthermore, the screw nut is a hollow reducer, which includes a large diameter section and a small diameter section, the small diameter section extends into the large diameter section, the large diameter section is located at the bottom of the large diameter section and a connecting hole is opened on the large diameter section.

[0013] Furthermore, the upper end of the ball screw is connected to a first elastic limiter, the upper end of the small diameter section is glued to a second elastic limiter, the second elastic limiter is provided with a supporting step for supporting the first elastic limiter, and a notch is symmetrically opened on the lower outer wall of the ball screw.

[0014] Furthermore, four guide rods are installed between the guide plate and the lower cover, the upper end of each guide rod is fixedly connected to the lower cover, and the lower end of each guide rod is installed on the guide plate through a linear bearing. A mounting groove is opened in the middle of the guide plate, and a pair of screw fixing blocks are arranged in the mounting groove. The screw fixing blocks are inserted into the notch and fixedly connected to the guide plate.

[0015] Furthermore, the support frame includes a support plate and support rods fixedly arranged on four corners of the support plate, both sides of the support plate are folded upward to form retaining edges, and a plurality of weight-reducing holes are opened on the support plate.

[0016] Furthermore, a control box and a power box electrically connected to the driving assembly are respectively provided on both sides of the driving assembly on the support plate, an elliptical air outlet is opened on the mounting base plate, a sealing ring is provided at the edge of the air outlet, the damper plate is also elliptical, and its bottom area is larger than the area of ​​the air outlet.

[0017] The beneficial effects of the utility model are:

[0018] (1) The driving assembly and lifting assembly of the utility model are distributed longitudinally, and the lifting assembly is partially lifted and lowered inside the driving assembly, which greatly reduces the installation height of the entire damper actuator;

[0019] (2) The drive assembly of the utility model adopts the structure of a motor, and the rotating shaft is changed into a hollow variable diameter shaft, which allows the ball screw to extend into the rotating shaft, and part of the stroke of the ball screw is completed in the rotating shaft. On the other hand, it is convenient to install the rotor core, magnetic steel and stator;

[0020] (3) A circle of cylindrical holes is opened on the bottom surface of the large diameter section of the hollow reducer shaft, which is convenient for connecting the screw nut, reduces weight, and helps dissipate heat;

[0021] (4) A brake is installed on the small diameter section of the hollow reducer shaft. The brake acts after the shaft stops rotating, and the brake is not powered at this time. There is no energy consumption while maintaining thrust, so precise control is achieved;

[0022] (5) The rotation of the shaft is controlled by the controller, and the damper actuator can be stopped and started at will within the entire stroke;

[0023] (6) The drive assembly is provided with a cover, and the brake and motor structure parts are placed in layers, which is easy to implement and maintain; the lower cover of the cover is provided with a second through hole with a variable diameter structure, which is convenient for installing the lower bearing, and the ring edge plays a protective role on the screw nut;

[0024] (7) A waterproof cover is provided to prevent moisture and dust outside the vehicle from entering the drive assembly, thereby ensuring the performance of the drive assembly; the waterproof upper pressing piece and the waterproof lower pressing piece are embedded in the installation, saving space and ensuring the firmness of the waterproof cover connection; and the waterproof cover also has the function of reducing noise;

[0025] (8) The screw nut is also a reducer to ensure the stability of its installation, thereby ensuring the smooth movement of the ball screw;

[0026] (9) The stroke of the ball screw is the maximum stroke of the entire damper actuator. The upper end of the ball screw is connected to the first elastic limiter for the maximum stroke limit. The second elastic limiter on the screw nut acts as a buffer for the first elastic limiter.

[0027] (10) A guide rod is arranged between the guide plate and the support frame. The travel of the guide rod is the minimum travel of the entire damper actuator. The guide rod also further ensures the stability of the up and down movement of the damper plate and prevents the damper plate from rotating. A notch is arranged at the lower part of the ball screw and a pair of screw fixing blocks are arranged in the mounting groove of the guide plate, which are convenient for connection with the ball screw, and the connection is reliable and easy to disassemble and assemble;

[0028] (11) Upward-turned ribs are provided on both sides of the support frame to facilitate the installation of the support frame and to protect the drive components, etc., thereby ensuring the stability of the entire damper actuator;

[0029] (12) The control box and power box are respectively installed on both sides of the drive assembly to achieve unified installation, save time and ensure installation efficiency;

[0030] (13) The utility model has a more compact structure and a more reasonable design, which meets the requirements of lightweight rail transit and can ensure waterproof requirements, reduce the number of maintenance times and extend the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The utility model is further described below in conjunction with the accompanying drawings and implementation modes.

[0032] Figure 1 It is a structural schematic diagram of the utility model.

[0033] Figure 2 It is a structural schematic diagram of the support frame in the utility model.

[0034] Figure 3 It is a structural schematic diagram of the drive assembly without the cover in the utility model.

[0035] Figure 4 It is a schematic diagram of the installation of the lifting component in the utility model.

[0036] Figure 5 The utility model is a schematic diagram of the installation of the screw nut and the screw.

[0037] Figure 6 It is a schematic diagram of the installation of the ball screw and the guide plate in the utility model.

[0038] Figure 7 It is a structural schematic diagram of the cover shell in the utility model.

[0039] Figure 8 yes Figure 7 Schematic diagram of the structure of the middle and lower cover.

[0040] Fig. 9 It is a schematic diagram of the installation of the waterproof cover in the utility model.

[0041] In the figure: 1. Installation base plate, 1-1. Air outlet, 2. Air damper plate, 3. Support frame, 31. Support plate, 311. Retaining edge, 312. Weight reduction hole, 32. Support rod, 4. Lifting assembly, 41. Ball screw, 411. Notch, 42. Screw nut, 421. Large diameter section, 4211. Connecting hole, 422. Small diameter section, 5. Drive assembly, 50. Cover, 501. Shell, 5011. Partition, 50111. First through hole, 502. Upper cover, 503. Lower cover, 5031. Second through hole, 50311. Large diameter part, 50312. Small diameter part, 5032. Ring edge, 5 033. Ring groove, 51. Rotating shaft, 511. Large diameter section, 5111. Cylindrical hole, 512. Small diameter section, 52. Rotor core, 53. Magnet, 54. Stator, 55. Brake, 56. Upper bearing, 57. Lower bearing, 6. Control box, 7. Power box, 8. Sealing ring, 9. Guide plate, 91. Mounting groove, 10. Waterproof cover, 101. Upper connecting edge, 102. Lower connecting edge, 11. Waterproof upper pressure plate, 12. Waterproof lower pressure plate, 13. First elastic limiter, 14. Second elastic limiter, 141. Support step, 15. Guide rod, 16. Linear bearing, 17. Screw fixing block. DETAILED DESCRIPTION

[0042] The present invention is now further described in conjunction with the accompanying drawings. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0043] like Figure 1 to Figure 3 As shown, a damper actuator of a rail transit fresh air system includes a mounting base plate 1, a damper plate 2, a support frame 3, a lifting assembly 4, and a driving assembly 5 for driving the lifting assembly 4, wherein the driving assembly 5 has a housing 50. Figure 2 As shown, the support frame 3 includes a support plate 31 and support rods 32 fixedly arranged at the four corners of the support plate 31. Both sides of the support plate 31 are folded upward to form retaining edges 311. The support plate 31 is provided with a plurality of weight-reducing holes 312. Figure 1 and Figure 3 As shown, a control box 6 and a power box 7 electrically connected to the driving assembly 5 are respectively arranged on both sides of the driving assembly 5 on the support plate 31, an elliptical air outlet 1-1 is opened on the mounting base plate 1, a sealing ring 8 is arranged at the edge of the air outlet 1-1, and the damper plate 2 is also elliptical, and its bottom area is larger than the area of ​​the air outlet 1-1 to ensure the effectiveness of closing the damper plate 2.

[0044] like Figure 3As shown, the driving assembly 5 is installed on the support frame 3, and the driving assembly 5 includes a rotating shaft 51, a rotor core 52, a magnet 53 and a stator 54. The rotating shaft 51 is a hollow variable diameter shaft, which includes a large diameter section 511 and a small diameter section 512. The rotor core 52 is installed on the upper part of the large diameter section 511, and a circle of cylindrical holes 5111 are evenly opened on the bottom surface of the large diameter section 511. The magnet 53 and the stator 54 are arranged in sequence outside the rotor core 52, and a brake 55 is installed on the upper part of the small diameter section 512.

[0045] like Figure 4 As shown, the lifting assembly 4 has a ball screw 41 and a screw nut 42. The screw nut 42 is installed on the ball screw 41 and fixed to the bottom surface of the large diameter section 511. The upper part of the ball screw 41 extends into the hollow part of the rotating shaft 51. The lower end of the ball screw 41 is connected to the guide plate 9, and the guide plate 9 is fixed in the middle of the top of the damper plate 2.

[0046] like Figure 5 As shown, the screw nut 42 is a hollow reducer, which includes a large diameter section 421 and a small diameter section 422. The small diameter section 422 extends into the large diameter section 511, and the large diameter section 421 is located at the bottom of the large diameter section 511 and a connecting hole 4211 is provided on the large diameter section 421. The upper end of the ball screw 41 is connected to a first elastic stopper 13 (rubber or nylon material), and the upper end of the small diameter section 422 is glued to a second elastic stopper 14 (rubber or nylon material), and the second elastic stopper 14 is provided with a support step 141 for supporting the first elastic stopper 13, and a notch 411 is symmetrically provided on the lower outer wall of the ball screw 41.

[0047] like Figure 4 and Figure 6 As shown, four guide rods 15 are installed between the guide plate 9 and the lower cover 503, the upper end of each guide rod 15 is fixedly connected to the lower cover 503, and the lower end of each guide rod 15 is installed on the guide plate 9 through a linear bearing 16. A mounting groove 91 is opened in the middle of the guide plate 9, and a pair of screw fixing blocks 17 are arranged in the mounting groove 91. The screw fixing blocks 17 are inserted into the notch 411 and are fixedly connected to the guide plate 9.

[0048] like Figure 3 and Figure 7 As shown, the housing 50 includes a shell 501, an upper cover 502 and a lower cover 503. The upper part of the shell 501 has a partition 5011. The middle of the partition 5011 is provided with a first through hole 50111 for the small diameter section 512 of the rotating shaft 51 to pass through. The inner wall of the first through hole 50111 is provided with an upper bearing 56 that is interference fit with the rotating shaft 51. The brake 55 is arranged between the upper cover 502 and the partition 5011. Figure 8As shown, a second through hole 5031 is provided in the middle of the lower cover 503 for the large diameter section 511 of the rotating shaft 51 to pass through. The second through hole 5031 is a variable diameter hole, which includes a large diameter portion 50311 and a small diameter portion 50312. A lower bearing 57 that is interference fit with the rotating shaft 51 is provided on the inner wall of the large diameter portion 50311, and the edge of the small diameter portion 50312 extends downward to form a ring edge 5032 that is clearance fit with the screw nut 42.

[0049] like Figure 8 and Fig. 9 As shown, a flexible waterproof cover 10 (which may be made of rubber) is arranged between the lower cover 503 and the guide plate 9. The waterproof cover 10 is in a tower-shaped structure, and an upper connecting edge 101 and a lower connecting edge 102 are arranged on its upper and lower edges respectively. An annular groove 5033 is provided on the outer side of the annular edge 5032 of the bottom surface of the lower cover 503, and a waterproof upper pressing sheet 11 connected to the upper connecting edge 101 is arranged in the annular groove 5033. A waterproof lower pressing sheet 12 connected to the lower connecting edge 102 is arranged on the upper surface of the guide plate 9.

[0050] The working principle is as follows: when the damper actuator of the present embodiment receives a door closing signal, the control box 6 controls the rotating shaft 51 to rotate in one direction, driving the screw nut 42 to rotate, so that the ball screw 41 moves downward, driving the linear bearing 16 to move downward along with the guide plate 9 and the damper plate 2. When the damper plate 2 is about to contact the sealing ring 8, the control box 6 controls the brake 55 to perform the braking action until the damper plate 2 is completely closed. At this time, the first elastic limiter 13 at the upper end of the ball screw 41 is limited on the supporting step 141 of the second elastic limiter 14 at the upper end of the screw nut 42, further reducing the noise; when receiving a door opening signal, the control box 6 controls the rotating shaft 51 to rotate in the opposite direction, driving the damper plate 2 to leave the air outlet 1-1; the control box 6 can control the rotating shaft 51 and the brake 55 to stop at any stroke position, accurately control the flow rate, and thus achieve the purpose of accurately controlling the air volume.

[0051] In addition, the damper actuator of this embodiment has been tested for 2 million times of opening and closing, and its opening speed is within 150ms, with fast and effective response. In addition, the existing pressure wave protection (protection) device / pressure wave air valve will also be equipped with a damper plate on the outside of the installation base plate, because the damper plate driven by the cylinder cannot completely guarantee the sealing after closing, and the damper plate on the outside also needs to be controlled separately; while the damper actuator of this embodiment only needs one damper plate to ensure the sealing after closing.

[0052] The above-mentioned implementation mode is only for illustrating the technical concept and features of the utility model, and its purpose is to enable people familiar with this technology to understand the content of the utility model and implement it. It cannot be used to limit the protection scope of the utility model. All equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A damper actuator for a rail transit fresh air system, characterized in that: The invention comprises a mounting base plate (1), a damper plate (2), a support frame (3), a lifting assembly (4), and a driving assembly (5) for driving the lifting assembly (4) to move. The driving assembly (5) is mounted on the support frame (3). The driving assembly (5) comprises a rotating shaft (51), a rotor core (52), a magnetic steel (53), and a stator (54). The rotating shaft (51) is a hollow variable diameter shaft, comprising a large diameter section (511) and a small diameter section (512). The rotor core (52) is mounted on the upper part of the large diameter section (511). The bottom surface of the large diameter section (511) is evenly provided with a circle of cylindrical A hole (5111) is provided outside the rotor core (52), and a magnetic steel (53) and a stator (54) are arranged in sequence. A brake (55) is installed on the upper part of the small diameter section (512). The lifting assembly (4) comprises a ball screw (41) and a screw nut (42). The screw nut (42) is installed on the ball screw (41) and fixed on the bottom surface of the large diameter section (511). The upper part of the ball screw (41) extends into the hollow part of the rotating shaft (51). The lower end of the ball screw (41) is connected to a guide plate (9). The guide plate (9) is fixed to the middle of the top of the damper plate (2).

2. The damper actuator of the rail transit fresh air system according to claim 1, characterized in that: The drive assembly (5) has a cover (50), the cover (50) comprising a shell (501), an upper cover (502) and a lower cover (503), the shell (501) having a partition (5011) in the upper part thereof, a first through hole (50111) for a small diameter section (512) of a rotating shaft (51) to pass through is provided in the middle of the partition (5011), an upper bearing (56) which is interference fit with the rotating shaft (51) is provided on the inner wall of the first through hole (50111), and the brake (55) is arranged between the upper cover (502) and the partition (5011).

3. The damper actuator of the rail transit fresh air system according to claim 2, characterized in that: A second through hole (5031) is provided in the middle of the lower cover (503) for the large diameter section (511) of the rotating shaft (51) to pass through. The second through hole (5031) is a variable diameter hole, comprising a large diameter portion (50311) and a small diameter portion (50312). A lower bearing (57) having an interference fit with the rotating shaft (51) is provided on the inner wall of the large diameter portion (50311). The edge of the small diameter portion (50312) extends downward to form a ring edge (5032) having a clearance fit with the screw nut (42).

4. The damper actuator of the rail transit fresh air system according to claim 3 is characterized in that: A flexible waterproof cover (10) is provided between the lower cover (503) and the guide plate (9); the waterproof cover (10) is in a tower-shaped structure, and an upper connecting edge (101) and a lower connecting edge (102) are provided on the upper and lower edges thereof, respectively.

5. The damper actuator of the rail transit fresh air system according to claim 4, characterized in that: An annular groove (5033) is provided on the outer side of the annular edge (5032) on the bottom surface of the lower cover (503), and a waterproof upper pressing plate (11) connected to the upper connecting edge (101) is provided in the annular groove (5033). A waterproof lower pressing plate (12) connected to the lower connecting edge (102) is provided on the upper surface of the guide plate (9).

6. The damper actuator of the rail transit fresh air system according to claim 2, characterized in that: The screw nut (42) is a hollow diameter reducing member, comprising a large diameter section (421) and a small diameter section (422), the small diameter section (422) extending into the large diameter section (511), the large diameter section (421) being located at the bottom of the large diameter section (511) and having a connecting hole (4211) formed on the large diameter section (421).

7. The damper actuator of the rail transit fresh air system according to claim 6, characterized in that: The upper end of the ball screw (41) is connected to a first elastic stopper (13), the upper end of the small diameter section (422) is glued to a second elastic stopper (14), the second elastic stopper (14) is provided with a support step (141) for supporting the first elastic stopper (13), and a notch (411) is symmetrically provided on the lower outer wall of the ball screw (41).

8. The damper actuator of the rail transit fresh air system according to claim 7, characterized in that: Four guide rods (15) are arranged between the guide plate (9) and the lower cover (503); the upper end of each guide rod (15) is fixedly connected to the lower cover (503); the lower end of each guide rod (15) is mounted on the guide plate (9) via a linear bearing (16); a mounting groove (91) is provided in the middle of the guide plate (9); a pair of screw rod fixing blocks (17) are arranged in the mounting groove (91); the screw rod fixing blocks (17) are inserted into the notch (411) and are fixedly connected to the guide plate (9).

9. The damper actuator of a rail transit fresh air system according to claim 1, characterized in that: The support frame (3) comprises a support plate (31) and support rods (32) fixedly arranged at four corners of the support plate (31); two sides of the support plate (31) are folded upward to form retaining edges (311); and a plurality of weight-reducing holes (312) are provided on the support plate (31).

10. The damper actuator of the rail transit fresh air system according to claim 9, characterized in that: A control box (6) and a power box (7) electrically connected to the drive assembly (5) are respectively arranged on both sides of the drive assembly (5) on the support plate (31); an elliptical air outlet (1-1) is provided on the mounting base plate (1); a sealing ring (8) is arranged at the edge of the air outlet (1-1); the air damper plate (2) is also elliptical, and its bottom area is larger than the area of ​​the air outlet (1-1).

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