A fan with a water vapor sealing structure

Abstract

This invention relates to the field of fan technology, specifically disclosing a fan with a water vapor sealing structure, comprising: a fixed base, a housing on the front of the fixed base, a main shaft assembly on the fixed base, at least a portion of the main shaft end of the main shaft assembly being located inside the housing; an impeller, the impeller being disposed inside the housing and connected to the main shaft end; a water vapor sealing mechanism, disposed between the main shaft assembly and the housing, and connected to both the main shaft end and the housing; the water vapor sealing mechanism includes a sealing shell, the sealing shell being sleeved on the main shaft end and connected to the housing, and within the sealing shell, along the direction from the housing to the main shaft assembly, a labyrinth seal assembly, a negative pressure seal assembly, and a media seal assembly are sequentially arranged, all sleeved on the main shaft end, with the negative pressure seal assembly communicating with the air inlet of the housing. This invention solves the problem of existing fan sealing structures being simple and easily damaged, leading to the leakage of harmful gases.

Description

Technical Field

[0001] This invention relates to the field of fan technology, and in particular to a fan with a water vapor sealing structure. Background Technology

[0002] In NMP (N-methylpyrrolidone) solvent recovery equipment, the core function of the blower is to draw the waste gas containing NMP solvent to the condensation equipment for cooling and recovery. NMP solvent itself is toxic and has high economic value for recovery. Therefore, the reliability of the sealing structure of the blower used in such equipment is crucial.

[0003] Currently, most blowers on the market use a single lip seal structure. However, during long-term operation, due to the potential corrosiveness of NMP exhaust gases or wear caused by high temperatures and high-speed rotation, single lip seals are prone to aging and damage. Once the lip seal fails, harmful gases will leak from the blower, causing environmental pollution, wasting valuable NMP solvent, and posing a threat to the health of on-site operators. Therefore, existing single-seal structures cannot meet the stringent requirements of the NMP equipment industry for environmental protection, economy, and safety. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the purpose of the present invention is to provide a fan with a water vapor sealing structure, so as to solve the problem that the sealing structure of the existing fan is simple and easy to be damaged, resulting in the leakage of harmful gases.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A fan with a water vapor sealing structure, comprising: A mounting base is provided with a housing on its front side and a spindle assembly is provided on the top wall of the mounting base, with at least a portion of the spindle end of the spindle assembly located inside the housing. An impeller is disposed inside the housing and connected to the main shaft end; A water vapor sealing mechanism is disposed between the main shaft assembly and the housing, and is connected to both the main shaft end and the housing. The water vapor sealing mechanism includes a sealing shell, which is sleeved on the main shaft end and connected to the machine housing. Inside the sealing shell, a labyrinth sealing assembly, a negative pressure sealing assembly, and a medium sealing assembly are sequentially arranged along the direction from the machine housing to the main shaft assembly. The labyrinth sealing assembly, the negative pressure sealing assembly, and the medium sealing assembly are all sleeved on the main shaft end. The negative pressure sealing assembly is connected to the air inlet of the machine housing.

[0006] Compared to existing technologies, this application establishes a moisture sealing mechanism between the main shaft assembly and the housing, and arranges a labyrinth seal assembly, a negative pressure seal assembly, and a media seal assembly sequentially along the direction from the housing to the main shaft assembly within the sealing shell, forming a triple synergistic sealing structure. This significantly improves sealing reliability compared to existing single lip seals. The labyrinth seal assembly acts as the first barrier to throttle and reduce the pressure of leaked gas, while the negative pressure seal assembly is connected to the air inlet of the housing. It actively draws in leaked gas by utilizing the negative pressure environment on the air inlet side when the fan is running, thus achieving a shift from passive to active sealing. This effectively prevents moisture and NMP harmful gases from leaking outward along the main shaft end, meeting the high sealing requirements of the fan.

[0007] As a preferred embodiment of the present invention, the water vapor sealing mechanism further includes a reinforcing ring, which is disposed between the housing and the sealing shell. The reinforcing ring is fixedly connected to the housing, and the sealing shell is detachably disposed on the reinforcing ring.

[0008] By adopting the above-described solution, a reinforcing ring is installed between the casing and the sealing shell, and the sealing shell is detachably mounted on the reinforcing ring. This enhances the structural strength and stability of the connection between the casing and the sealing shell, while also facilitating the overall disassembly and installation of the sealing shell. When maintenance, repair, or replacement of the internal sealing components is required, the sealing shell can simply be removed from the reinforcing ring without damaging the casing or other components, significantly improving the maintainability and assembly convenience of the fan.

[0009] As a preferred embodiment of the present invention, a first sealing ring is provided between the reinforcing ring and the sealing shell.

[0010] By employing the above-described solution, a first sealing ring is placed between the reinforcing ring and the sealing shell, effectively sealing the minute gaps at their mating surfaces and preventing gas from leaking directly into the outside atmosphere from this connection point. This static sealing structure, serving as an auxiliary sealing layer for the water vapor sealing mechanism, further improves the overall sealing performance of the sealing system, avoiding the risk of seal failure due to leakage at the installation interface.

[0011] As a preferred embodiment of the present invention, an annular placement groove is provided on one end face of the sealing shell near the reinforcing ring, and the first sealing ring is located in the annular placement groove.

[0012] By employing the above-described solution, a ring-shaped groove is provided on the end face of the sealing shell near the reinforcing ring, and the first sealing ring is placed within it, achieving precise positioning and reliable fixation of the sealing ring. This structure prevents the sealing ring from shifting, twisting, or falling off during assembly or disassembly, ensuring that the first sealing ring is in the correct sealing position after each installation, thereby guaranteeing the long-term stability and consistency of the sealing at the mating surfaces.

[0013] As a preferred embodiment of the present invention, the labyrinth sealing assembly includes a labyrinth sealing plate, which is located between the reinforcing ring and the negative pressure sealing assembly. A pressing protrusion is provided on the inner wall of the sealing shell corresponding to the labyrinth sealing plate. The pressing protrusion is used to apply a pressing force to the labyrinth sealing plate so that the labyrinth sealing plate fits against the reinforcing ring. A plurality of sealing ring grooves are provided on the contact surface between the labyrinth sealing plate and the spindle end.

[0014] By employing the above-described scheme, a labyrinth sealing plate is installed, and multiple sealing ring grooves are machined on its contact surface with the spindle end, forming multiple tortuous sealing channels. When leaking gas flows through these sealing ring grooves, eddies and throttling effects are generated within the grooves, causing the gas pressure to decrease step by step, thereby significantly reducing the amount of gas leaking outward along the spindle end. Simultaneously, the clamping protrusions on the inner wall of the sealing shell reliably press the labyrinth sealing plate to fit snugly against the reinforcing ring, ensuring the stability of the sealing gap and improving the sealing effect.

[0015] As a preferred embodiment of the present invention, the negative pressure sealing assembly includes: A centrifugal auxiliary impeller is provided, and a negative pressure cavity is formed between the sealing shell, the labyrinth seal assembly, and the medium seal assembly. The centrifugal auxiliary impeller is disposed in the negative pressure cavity and sleeved on the main shaft end. The return air duct has a first opening in the sealing shell corresponding to the negative pressure cavity, and a second opening in the housing corresponding to the air inlet. One end of the return air duct is connected to the negative pressure cavity through the first opening, and the other end is connected to the air inlet of the housing through the second opening. The height of the first opening in the vertical direction is greater than the height of the second opening in the vertical direction, so that the return air duct is tilted towards the second opening.

[0016] By employing the above-described scheme and incorporating a centrifugal auxiliary impeller and a return air duct, an active negative pressure suction sealing mechanism is established. The rotation of the main shaft drives the centrifugal auxiliary impeller to rotate at high speed, generating a suction effect within the negative pressure cavity. Furthermore, the return air duct is connected to the air inlet of the casing, creating a strong negative pressure state within the cavity. This effectively draws the minute amount of leaked gas passing through the labyrinth seal assembly back into the air inlet of the casing, achieving internal gas circulation. Simultaneously, the downward-sloping design of the return air duct allows any NMP solvent waste that may condense during leakage to flow back into the casing by gravity, preventing waste accumulation or leakage, thus protecting the environment and improving solvent recovery rates.

[0017] As a preferred embodiment of the present invention, the sealing shell is provided with an inspection port corresponding to the centrifugal auxiliary wheel, and a sealing plug is detachably provided at the inspection port.

[0018] By adopting the above-described solution, an inspection port is provided at the location of the centrifugal auxiliary impeller on the sealing shell, and a detachable sealing plug is installed at the inspection port. This allows operators to observe, inspect, or replace the centrifugal auxiliary impeller without disassembling the entire sealing shell. This structure greatly facilitates daily maintenance work, reduces repair difficulty and downtime, and ensures a reliable seal of the inspection port during normal operation without affecting the sealing performance.

[0019] As a preferred embodiment of the present invention, the medium sealing assembly includes: The second sealing ring and the third sealing ring are provided with an end cap detachably provided on one end face of the sealing shell near the spindle assembly. The second sealing ring and the third sealing ring are provided inside the sealing shell near the end cap and are both sleeved on the spindle end. The third sealing ring is fitted to the end cap. A positioning ring is disposed between the second sealing ring and the third sealing ring, and the positioning ring is respectively fitted to the second sealing ring and the third sealing ring, forming a medium cavity between the second sealing ring, the positioning ring and the third sealing ring; The inner wall of the sealing shell is provided with a limiting protrusion ring corresponding to the second sealing ring, and the limiting protrusion ring presses the second sealing ring against the positioning ring.

[0020] Using the above-described scheme, a sealed media cavity is formed within the sealing housing near the main shaft assembly through the combined action of the second and third sealing rings and the positioning ring. This media cavity can contain and retain the sealing medium, forming a highly reliable media isolation barrier between the main shaft end and the sealing rings. The limiting protrusion reliably presses the second sealing ring against the positioning ring, ensuring the axial sealing of the media cavity. Even if a trace amount of gas escapes into this cavity from the first two stages of sealing, it will be effectively blocked by the media barrier, thus achieving a near-zero leakage ultimate sealing effect.

[0021] As a preferred embodiment of the present invention, the positioning ring has a groove on its side and a filling hole on the bottom wall of the groove, the filling hole being connected to the medium cavity.

[0022] By employing the above-described scheme, an annular groove is created on the side of the positioning ring, and a filling hole communicating with the media cavity is formed on the bottom wall of the groove, thus creating a smooth media filling channel. The annular groove structure increases the contact area and flow range during media filling, allowing the sealing medium to uniformly and fully fill the entire media cavity, avoiding filling dead zones. This structure ensures that the sealing medium within the media cavity remains fully saturated, thereby maintaining the long-term effectiveness and stability of the media sealing assembly.

[0023] As a preferred embodiment of the present invention, the sealing shell is provided with a filling nozzle at the position corresponding to the filling hole, and the filling nozzle is used to fill the medium cavity with medium.

[0024] By adopting the above solution, by setting the filling nozzle on the sealing shell at the position corresponding to the filling hole, the operator can conveniently add sealing medium into the medium cavity without disassembling any parts. This makes the daily maintenance and replenishment of the medium sealing assembly extremely convenient, which is conducive to maintaining the long-term reliable operation of the sealing system and avoiding the risk of seal failure due to lack of medium.

[0025] The aforementioned fan with a water vapor sealing structure has the following beneficial effects: A three-stage composite sealing structure is formed by sequentially arranging a labyrinth seal assembly, a negative pressure seal assembly, and a media seal assembly within the sealing housing along the direction from the housing to the main shaft assembly. The labyrinth seal assembly throttles and reduces the pressure of leaked gas; the negative pressure seal assembly actively draws back the trace amount of gas passing through the labyrinth seal assembly to the housing interior using the negative pressure environment connected to the housing inlet; and the media seal assembly acts as the final barrier to isolate residual gas. The synergistic effect of the three-stage seals significantly reduces the leakage of harmful gases at the main shaft end, effectively preventing the leakage of toxic solvents such as NMP, while simultaneously improving the overall reliability and redundancy of the sealing system. This solves the problems of easy damage and leakage in existing single-seal structures, meeting the requirements for environmental protection, safety, and economical solvent recovery. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a fan with a water vapor sealing structure according to the present invention; Figure 2 This is a schematic diagram of the water vapor sealing mechanism in a fan with a water vapor sealing structure according to the present invention; In the diagram: 1. Fixed base; 2. Housing; 21. Air inlet; 22. Second opening; 3. Main shaft assembly; 31. Main shaft end; 4. Impeller; 5. Water vapor sealing mechanism; 51. Sealing shell; 511. Pressing protrusion; 512. Limiting protrusion; 513. First opening; 514. Inspection port; 515. End cover; 516. Annular placement groove; 52. Labyrinth seal assembly; 521. Labyrinth seal plate; 522. Sealing ring groove; 53. Negative pressure seal assembly; 531. Centrifugal auxiliary impeller; 532. Negative pressure cavity; 533. Return air duct; 54. Medium sealing assembly; 541. Second sealing ring; 542. Third sealing ring; 543. Positioning ring; 544. Medium cavity; 545. Ring groove; 546. Filling hole; 55. Reinforcing ring; 56. First sealing ring; 57. Filling nozzle; 58. Sealing plug.

[0027] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] To make the above-mentioned objectives and beneficial effects of the present invention more apparent and easily understood, a fan with a water vapor sealing structure provided by the present invention will be described in detail below with reference to the accompanying drawings and multiple embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0030] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0031] Example like Figure 1 As shown, this embodiment provides a fan with a water vapor sealing structure, which is mainly used in NMP (N-methylpyrrolidone) solvent recovery systems to pump gas containing NMP solvent. The fan includes a fixed base 1, a casing 2, a main shaft assembly 3, an impeller 4, and a water vapor sealing mechanism 5.

[0032] The mounting base 1 serves as the foundation for the fan, with the housing 2 fixedly mounted on its front. A main shaft assembly 3 is mounted on the top wall of the mounting base 1. The main shaft assembly 3 is a conventional combination of a bearing housing and a main shaft, with its main shaft end 31 driven to rotate by a drive motor. Since this main shaft assembly 3 is known in the art and this application does not modify its internal structure, it will not be described in detail here. At least a portion of the main shaft end 31 extends into the housing 2. The impeller 4 is disposed within the housing 2 and fixedly mounted to the end of the main shaft end 31 via a key connection or interference fit. Driven by the main shaft end 31, it rotates at high speed, thereby generating a negative pressure airflow within the housing 2.

[0033] like Figure 2 As shown, the water vapor sealing mechanism 5 is located at the connection between the spindle assembly 3 and the housing 2, and is sealed to both the spindle end 31 and the housing 2 to prevent toxic gases inside the housing 2 from leaking outward along the spindle end 31. The water vapor sealing mechanism 5 includes a sealing shell 51. The sealing shell 51 is entirely fitted onto the spindle end 31 and fixedly connected to the back of the housing 2. Inside the sealing shell 51, along the direction from the housing 2 to the spindle assembly 3, a labyrinth seal assembly 52, a negative pressure seal assembly 53, and a media seal assembly 54 are sequentially arranged. The labyrinth seal assembly 52, the negative pressure seal assembly 53, and the media seal assembly 54 are all fitted onto the spindle end 31 and form a precise sealing fit with it. The water vapor sealing mechanism 5 also includes a reinforcing ring 55. The reinforcing ring 55 is fixedly installed on the back of the housing 2 by welding. In other embodiments, the reinforcing ring 55 and the housing 2 can also be integrally cast, as long as a fixed connection between the reinforcing ring 55 and the housing 2 can be achieved. The specific connection method is not limited here. The sealing shell 51 is detachably mounted on the reinforcing ring 55 using multiple bolts. A first sealing ring 56 is provided between the mating surfaces of the reinforcing ring 55 and the sealing shell 51. Preferably, the first sealing ring 56 is a PTFE O-ring, which has good corrosion resistance and elasticity. An annular groove 516 is formed on the end face of the sealing shell 51 near the reinforcing ring 55, and the first sealing ring 56 is installed in this annular groove 516 to ensure accurate positioning and prevent displacement of the first sealing ring 56 during assembly.

[0034] like Figure 2As shown, the labyrinth seal assembly 52 includes one or more labyrinth seal plates 521. The labyrinth seal plate 521 is fitted onto the spindle end 31, and its contact surface with the spindle end 31 has multiple axially arranged sealing ring grooves 522. When gas flows through these sealing ring grooves 522, eddies and throttling effects are generated, causing the gas pressure to decrease step by step, thereby significantly reducing the amount of gas leaking outward along the spindle end 31. Furthermore, the inner wall of the sealing shell 51 has pressing protrusions 511 at positions corresponding to the labyrinth seal plates 521, and the pressing protrusions 511 are integrally formed on the sealing shell 51. When the sealing shell 51 is bolted onto the reinforcing ring 55, the pressing protrusions 511 apply axial pressing force to the labyrinth seal plate 521, making it tightly fit against the side of the reinforcing ring 55. This structure ensures that the labyrinth seal plate 521 will not experience axial movement during long-term operation, thus guaranteeing the stability of the sealing gap.

[0035] like Figure 2 As shown, the negative pressure sealing assembly 53 includes a centrifugal auxiliary impeller 531 and a return air duct 533. Inside the sealing shell 51, a negative pressure cavity 532 is formed by the labyrinth sealing assembly 52 and the media sealing assembly 54. The centrifugal auxiliary impeller 531 is fixedly sleeved on the main shaft end 31 by a set screw and is located inside the negative pressure cavity 532. The centrifugal auxiliary impeller 531 adopts a turbine fan as used in the prior art. When the main shaft end 31 rotates, the centrifugal auxiliary impeller 531 rotates synchronously at high speed, generating a centrifugal suction effect on the gas in the negative pressure cavity 532. A first opening 534 is opened on the side wall of the sealing shell 51 corresponding to the position of the negative pressure cavity 532, and a second opening 535 is opened at the air inlet 21 of the casing 2. One end of the return air duct 533 is connected to the negative pressure cavity 532 through the first opening 534, and the other end is connected to the air inlet 21 of the casing 2 through the second opening 535. To facilitate condensate recirculation, the first opening 534 is vertically higher than the second opening 535, causing the return air duct 533 to be tilted towards the second opening 535. When the fan is operating, the negative pressure at the air inlet 21 and the suction force generated by the centrifugal auxiliary impeller 531 work together to create a stronger negative pressure state within the negative pressure cavity 532, drawing leaked gas back to the air inlet 21 through the return air duct 533, achieving internal circulation. Simultaneously, the tilted design of the return air duct 533 allows the NMP solvent waste liquid condensed during leakage to flow back into the casing 2 by gravity, preventing waste liquid leakage.

[0036] like Figure 2As shown, the medium sealing assembly 54 includes a second sealing ring 541, a third sealing ring 542, and a positioning ring 543. An end cap 515 is detachably mounted on the end of the sealing housing 51 near the spindle assembly 3 via bolts. Both the second sealing ring 541 and the third sealing ring 542 are disposed inside the sealing housing 51 near the end cap 515 and are tightly fitted onto the spindle end 31. In this embodiment, both the second sealing ring 541 and the third sealing ring 542 are lip-type sealing rings, providing good dynamic sealing performance. The right side of the third sealing ring 542 is fitted against the end cap 515. The positioning ring 543 is disposed between the second sealing ring 541 and the third sealing ring 542, with its left and right end faces respectively fitting against the second sealing ring 541 and the third sealing ring 542, thereby forming a sealed medium cavity 544 together with the second sealing ring 541, the positioning ring 543, and the third sealing ring 542. On the inner wall of the sealing shell 51, a limiting protrusion ring 512 is provided corresponding to the left side position of the second sealing ring 541. The limiting protrusion ring 512 is integrally formed into the sealing shell 51. This limiting protrusion ring 512 presses the second sealing ring 541 to the right from the left, making it tightly fit against the positioning ring 543, thereby ensuring the axial sealing of the medium cavity 544. By injecting sealing medium into the medium cavity 544, a dense medium isolation barrier can be formed between the spindle end 31 and the two lip seals, effectively blocking any residual gas that has passed through the first two stages of sealing. In this embodiment, the sealing medium is a high-temperature resistant lubricating grease. In other embodiments, different sealing media, such as inert gases, can be used depending on the actual application scenario. No specific limitation is made on the type of sealing medium here. An annular groove 545 is provided on the side of the positioning ring 543. A filling hole 546 is provided on the bottom wall of the annular groove 545, which extends to the inner wall of the positioning ring 543 and is connected to the medium cavity 544. On the side wall of the sealing housing 51, a filling nozzle 57 is provided at a position corresponding to the filling hole 546. In this embodiment, the filling nozzle 57 adopts a standard grease nipple structure and is threaded onto the sealing housing 51. Operators can easily add lubricating grease to the medium cavity 544 by simply connecting the filling nozzle 57 with a standard tool such as a grease gun, without disassembling the end cap 515 or any sealing components. This structure ensures that the sealing medium in the medium cavity 544 is always in a full state, maintaining the long-term effectiveness of the medium sealing assembly 54.

[0037] An inspection port 514 is provided on the sealing housing 51 at the position corresponding to the centrifugal auxiliary impeller 531. During normal operation, the inspection port 514 is closed by a removable sealing plug 58. In this embodiment, the sealing plug 58 is a threaded plug with a sealing ring. When it is necessary to observe, repair or replace the centrifugal auxiliary impeller 531, it is only necessary to remove the sealing plug and operate through the inspection port 514 without disassembling the entire sealing housing 51, which greatly facilitates daily maintenance.

[0038] The working principle of this application is as follows: The drive motor rotates the main shaft of the main shaft assembly 3. When the main shaft end 31 rotates, the centrifugal auxiliary impeller 531 rotates along with the main shaft end 31. At this time, the centrifugal auxiliary impeller 531 blocks the leaking gas at the shaft outlet, thereby reducing the leaking gas at the shaft outlet. The cavity formed by the sealing ring groove 522 on the labyrinth sealing plate 521 helps to reduce the pressure of the leaking gas, thereby reducing the leaking gas at the shaft outlet. While the main shaft end 31 rotates, it drives the impeller 4 to rotate, making the inside of the air inlet 21 of the casing 2 a negative pressure state. This negative pressure environment is conducted through the return air pipe 533, making the inside of the sealing shell 51 also a negative pressure state. The gas leaking at the shaft outlet is drawn back into the air inlet 21 through the return air pipe 533, reducing the leakage of harmful gases. The sealed medium cavity 544 formed by the second sealing ring 541, the third sealing ring 542, and the positioning ring 543 is more conducive to reducing NMP solvent waste gas leakage; while the return air pipe 533 is inclined downward at a certain angle to the horizontal plane, which can also make the leaked condensed NMP solvent waste liquid flow back from the air inlet 21 to the housing 2, avoiding the leakage of condensed NMP solvent waste liquid and polluting the environment.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A fan with a water vapor sealing structure, characterized in that, include: A mounting base is provided with a housing on its front side and a spindle assembly is provided on the top wall of the mounting base, with at least a portion of the spindle end of the spindle assembly located inside the housing. An impeller is disposed inside the housing and connected to the main shaft end; A water vapor sealing mechanism is disposed between the main shaft assembly and the housing, and is connected to both the main shaft end and the housing. The water vapor sealing mechanism includes a sealing shell, which is sleeved on the main shaft end and connected to the machine housing. Inside the sealing shell, a labyrinth sealing assembly, a negative pressure sealing assembly, and a medium sealing assembly are sequentially arranged along the direction from the machine housing to the main shaft assembly. The labyrinth sealing assembly, the negative pressure sealing assembly, and the medium sealing assembly are all sleeved on the main shaft end. The negative pressure sealing assembly is connected to the air inlet of the machine housing.

2. The fan with a water vapor sealing structure according to claim 1, characterized in that, The water vapor sealing mechanism also includes a reinforcing ring, which is disposed between the housing and the sealing shell. The reinforcing ring is fixedly connected to the housing, and the sealing shell is detachably disposed on the reinforcing ring.

3. The fan with a water vapor sealing structure according to claim 2, characterized in that: A first sealing ring is provided between the reinforcing ring and the sealing shell.

4. The fan with a water vapor sealing structure according to claim 3, characterized in that: The sealing shell has an annular placement groove on one end face near the reinforcing ring, and the first sealing ring is located in the annular placement groove.

5. The fan with a water vapor sealing structure according to claim 2, characterized in that: The labyrinth sealing assembly includes a labyrinth sealing plate located between the reinforcing ring and the negative pressure sealing assembly. A pressing protrusion is provided on the inner wall of the sealing shell corresponding to the labyrinth sealing plate. The pressing protrusion is used to apply a pressing force to the labyrinth sealing plate so that the labyrinth sealing plate fits against the reinforcing ring. The contact surface between the labyrinth sealing plate and the spindle end is provided with multiple sealing ring grooves.

6. The fan with a water vapor sealing structure according to claim 1, characterized in that, The negative pressure sealing assembly includes: A centrifugal auxiliary impeller is provided, and a negative pressure cavity is formed between the sealing shell, the labyrinth seal assembly, and the medium seal assembly. The centrifugal auxiliary impeller is disposed in the negative pressure cavity and sleeved on the main shaft end. The return air duct has a first opening in the sealing shell corresponding to the negative pressure cavity, and a second opening in the housing corresponding to the air inlet. One end of the return air duct is connected to the negative pressure cavity through the first opening, and the other end is connected to the air inlet of the housing through the second opening. The height of the first opening in the vertical direction is greater than the height of the second opening in the vertical direction, so that the return air duct is tilted towards the second opening.

7. The fan with a water vapor sealing structure according to claim 6, characterized in that: The sealing shell is provided with an inspection port corresponding to the centrifugal auxiliary wheel, and a sealing plug is detachably provided at the inspection port.

8. The fan with a water vapor sealing structure according to claim 1, characterized in that, The medium sealing assembly includes: The second sealing ring and the third sealing ring are provided with an end cap detachably provided on one end face of the sealing shell near the spindle assembly. The second sealing ring and the third sealing ring are provided inside the sealing shell near the end cap and are both sleeved on the spindle end. The third sealing ring is fitted to the end cap. A positioning ring is disposed between the second sealing ring and the third sealing ring, and the positioning ring is respectively fitted to the second sealing ring and the third sealing ring, forming a medium cavity between the second sealing ring, the positioning ring and the third sealing ring; The inner wall of the sealing shell is provided with a limiting protrusion ring corresponding to the second sealing ring, and the limiting protrusion ring presses the second sealing ring against the positioning ring.

9. The fan with a water vapor sealing structure according to claim 8, characterized in that: The positioning ring has a groove on its side, and the bottom wall of the groove has a filling hole that is connected to the medium cavity.

10. The fan with a water vapor sealing structure according to claim 9, characterized in that: The sealing shell is provided with a filling nozzle at the position corresponding to the filling hole, and the filling nozzle is used to fill the medium cavity with medium.

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