Anti-fouling screw vacuum pump

Abstract

The utility model discloses a kind of anti-fouling screw vacuum pumps, including pump body and screw rotor, pump body is equipped with pump cavity, pump cavity is divided into two ends along screw rotor axis direction, one end is suction end, the other end is exhaust end. Pump cavity suction end is equipped with suction passage and at least one independent air bleed passage, air bleed passage is communicated with external gas source. By introducing external airflow through air bleed passage, can impact and break the disorder vortex generated in pump cavity, make it melt into main airflow, reduce energy loss, inhibit pollutant deposition. In addition, bearing chamber is communicated with gas source through air hole on end cover, form positive pressure environment, effectively block pollutant along rotor shaft end gap reverse intrusion bearing chamber, avoid abrasion and fouling. The utility model structure is simple and reliable, significantly improve the anti-fouling ability of vacuum pump, operating stability and service life.

Description

Technical Field

[0001] This utility model relates to the field of vacuum pump technology, and in particular to a dirt-proof screw vacuum pump. Background Technology

[0002] A screw vacuum pump is a device that uses the high-speed rotation of a screw rotor to achieve gas suction and compression. The screw rotor in a screw vacuum pump rotates at a high speed of thousands of revolutions per minute. The end of the screw rotor acts like a high-speed rotating fan blade, exerting a huge tangential force on the surrounding gas, propelling the gas along the direction of the screw's rotation.

[0003] During this process, an orderly, stable, and high-speed air vortex is formed at the end of the screw rotor at the suction end of the pump chamber, which improves the pumping efficiency and makes the intake process more stable.

[0004] However, when gas flows through the inner wall of the pump chamber, especially between the end of the screw rotor and the suction end face of the pump chamber, the airflow velocity near the wall slows down due to friction and viscosity. This creates a significant velocity difference with the ordered cyclones in this area, making it very easy for disordered cyclones to form between the end of the screw rotor and the suction end face of the pump chamber. These disordered cyclones typically do not participate in effective gas delivery; instead, they idle at low speed or flow in the opposite direction, consuming energy without doing any work. Furthermore, these low-speed cyclone zones are precisely where dust and particulate matter are most likely to deposit and accumulate, increasing the adhesion rate of contaminants on the pump chamber surface and accelerating wear, thus reducing its service life.

[0005] Furthermore, during operation, contaminants can easily enter the gap between the screw rotor and the shaft connection surface at the suction end of the pump chamber. This accumulation of contaminants not only accelerates the wear and failure of the journal and seals but also solidifies into scale that is difficult to remove. Conventional flushing methods are insufficient for thorough cleaning, necessitating frequent disassembly of the pump body for manual cleaning, significantly reducing the equipment's continuous operating time.

[0006] Therefore, in view of the shortcomings of the existing technology, it is necessary to design a dirt-proof screw vacuum pump to solve the above problems.

[0007] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solution of this utility model and facilitating the understanding of those skilled in the art. It should not be assumed that the above content is known to those skilled in the art simply because it has been described in the background section of this utility model. Utility Model Content

[0008] To overcome the shortcomings of the prior art, the present invention discloses a pollution-proof screw vacuum pump that suppresses the generation of disordered air cyclones by introducing a small amount of external airflow and prevents pollutants from entering the bearing chamber by air pressure difference (air barrier), thereby improving the pump's pollution-proof capability and operational reliability.

[0009] This utility model discloses a fouling-proof screw vacuum pump, including a pump body and a screw rotor. The pump body has a pump chamber for accommodating the screw rotor. One end of the pump chamber along the axis of the screw rotor is the suction end, and the other end is the exhaust end. The suction end of the pump chamber has a suction channel for drawing in the gas to be processed, and the exhaust end of the pump chamber has an exhaust channel for discharging the gas. The suction end of the pump chamber also has a priming channel for connecting the pump chamber with a gas source or the external environment. It should be noted that the suction end of the pump chamber is a low-pressure area, and the gas pressure of the gas source or the external environment is always higher than the gas pressure of the low-pressure area of ​​the pump chamber.

[0010] Preferred technical solution: The opening of the induced draft channel within the pump chamber is located on the side furthest from the intake channel. Disordered air cyclones are more easily generated on the side of the pump chamber's intake end furthest from the intake channel; therefore, placing the opening of the induced draft channel in this position improves the elimination of disordered air cyclones.

[0011] Preferred technical solution: A filter device and a valve for controlling the opening and closing of the air intake channel are provided.

[0012] Preferred technical solution: The gas source can be either a gas storage container or a gas generating device.

[0013] Preferred technical solution: A branch channel is provided between the air intake channel and the air duct to connect them, using the airflow in the air intake channel as the air source, thus avoiding reducing the pumping capacity of the anti-fouling screw vacuum pump.

[0014] A preferred technical solution: A sealing plate is installed at one end of the pump chamber near the suction channel. The shaft end of the screw rotor passes through the sealing plate and is rotatably connected to a bearing. The bearing is mounted on an end cover, and the end cover and the sealing plate together form a bearing chamber. At least one vent hole is provided through the end cover, connecting the bearing chamber to the air source. It should be noted that in conventional settings, the flow area of ​​the vent hole is greater than the sum of the area of ​​the connection gap at the screw rotor shaft end and the flow area of ​​the suction channel.

[0015] Preferred technical solution: The bearing chamber is connected to the induced draft channel.

[0016] Preferred technical solution: The outer periphery of the sealing plate is stepped; the air intake channel is set along the outer side of the sealing plate.

[0017] Preferred technical solution: A filter device and a valve for controlling its opening and closing are provided at the vent. The operation, shutdown, and cleaning of the vacuum pump are coordinated by controlling the valve.

[0018] Preferred technical solution: The pump body is equipped with two non-contact meshing screw rotors, the bearing chambers corresponding to the two screw rotors are interconnected, and the shaft ends of the two screw rotors are connected to the same sealing plate.

[0019] Due to the application of the above technical solution, the beneficial effects of this utility model compared with the prior art are as follows:

[0020] This invention relates to a dirt-proof screw vacuum pump. It utilizes an induced draft channel to introduce external airflow. As the external airflow merges into an ordered cyclone, it impacts and breaks up the disordered cyclone, thus suppressing its formation. This significantly reduces energy loss caused by airflow separation and eddies, improving gas delivery efficiency and inhibiting contaminant deposition. Furthermore, the induced draft channel can be connected to the intake channel, using the airflow in the intake channel as a gas source, avoiding a reduction in the screw vacuum pump's pumping capacity. Additionally, this invention features a vent hole running through the bearing chamber structure, introducing external gas into the bearing chamber and creating a stable positive pressure environment. This ensures that the gas in the bearing chamber always flows towards the pump cavity along the shaft end connection gap, forming a gas barrier (or gas barrier for short). This barrier prevents dust, oil mist, and particulate matter in the treated gas from reversing into the bearing chamber along the screw rotor shaft end connection gap, thus avoiding frequent disassembly and cleaning and improving continuous operation capability. Finally, in this invention, the induced draft channel can be arranged along the outer side of the stepped sealing plate, maximizing space utilization without affecting the overall structural strength. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a longitudinal sectional view of the anti-fouling screw vacuum pump in Embodiments 1 and 3;

[0023] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0024] Figure 3 This is a cross-sectional view of the anti-fouling screw vacuum pump in Embodiments 1 and 3;

[0025] Figure 4 This is a schematic diagram of the sealing plate in this utility model;

[0026] Figure 5 This is a longitudinal sectional view of the anti-fouling screw vacuum pump in Example 2.

[0027] In the above attached diagrams, 1 is the pump body; 11 is the pump chamber; 12 is the suction channel; 13 is the exhaust channel; 14 is the induced draft channel; 15 is the bearing chamber; 16 is the branch channel; 2 is the screw rotor; 3 is the sealing plate; 4 is the end cover; and 41 is the vent hole. Detailed Implementation

[0028] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the purposes of describing embodiments of this application herein. Furthermore, the terms "comprising" and "having," and their synonyms, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] In this application, the terms "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this utility model and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0031] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0032] Furthermore, the terms "installation," "setting," "equipped with," "connection," "linking," "fitting," and "fitting" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Similarly, "fitting" can mean completely or partially fitted. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] Example 1:

[0035] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, this utility model discloses a dirt-proof screw vacuum pump, including a pump body 1 and a screw rotor 2 disposed therein. The main components of the present utility model will be described in detail below:

[0036] A pump chamber 11 is formed inside the pump body 1 to accommodate the screw rotor 2. One end of the pump chamber 11 along the axis of the screw rotor 2 is the intake end, and the other end is the exhaust end. An intake channel 12 is provided at the intake end of the pump chamber 11 for receiving the pumped gas; an exhaust channel 13 is provided at the exhaust end of the pump chamber 11 for discharging the compressed gas. An induced draft channel 14 is provided at the intake end of the pump chamber 11, independent of the intake channel 12 and connected to the atmospheric environment. Because the intake end of the pump chamber 11 is a low-pressure area, gas from the atmospheric environment continuously enters the pump chamber 11 through the induced draft channel 14 under the action of pressure difference. This gas impacts the low-speed disordered cyclone formed by the wall adhesion, causing the low-speed disordered cyclone to break up and merge into the mainstream ordered cyclone, thereby significantly reducing energy loss and inhibiting the deposition of dust and particulate matter on the wall of the pump chamber 11. It should be noted that in this embodiment, the air intake channel 14 is connected to the atmospheric environment. However, in other embodiments, the air intake channel 14 may also be connected to a gas storage container, using the gas storage container to deliver positive air pressure into the pump chamber. It should also be noted that "low-speed disordered cyclones formed due to wall viscosity" are only one major cause of disordered cyclones, and do not mean that this invention can only solve disordered cyclones caused by this type of factor. Rather, any disordered cyclones existing at the suction end of the pump chamber 11 will be suppressed due to the above design.

[0037] In practical vacuum pump design, the equivalent diameter of the bleed channel 14 typically needs to be controlled between 0.1 mm and 4 mm. This range allows for effective airflow introduction to suppress disordered cyclones while controlling the additional gas flow rate, preventing a significant reduction in the ultimate vacuum and operating vacuum of the vacuum pump due to excessive bleed volume, thus ensuring that its core performance is not significantly affected. For example, in applications requiring high vacuum, an equivalent diameter of 0.1 mm can be selected for the bleed channel, with an equivalent flow area of ​​approximately 7.85 × 10⁻⁶. -5 The actual conductivity is less than 0.0009 L / s. Such a small conductivity, for a vacuum pump with a pumping speed of 100 L / s, would only introduce additional leakage that would lower the ultimate vacuum from 1 × 10⁻⁶ cm². -3Pa slightly worsened to 2×10 -3 The effect on Pa is relatively limited. At this time, the bleed air channel can still maintain its function of suppressing disordered cyclones. In addition, by extending the length of the bleed air channel in a stepped arrangement, the conductance can be further reduced, thus reducing the adverse effects on the ultimate vacuum.

[0038] When the equivalent diameter of the bleed channel increases to 4 mm, its equivalent flow area is approximately 0.1256 cm², and the actual conductance can reach 0.156 L / s. Even with increased channel length, the conductance can typically only be controlled to 0.1 L / s, which has a significant impact on vacuum pump performance. If the channel diameter is further increased, the loss in vacuum level will outweigh the benefits of suppressing disordered cyclones. Therefore, a balance between these two aspects must be considered in the design.

[0039] Further optimize the above design, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the opening of the induced draft channel 14 is located in the pump chamber 11 on the side away from the intake channel 12. This area is far from the intake channel 12, and the internal gas flow is chaotic and slow, making it prone to generating disordered cyclones. Introducing gas from the atmospheric environment directly into this area through the induced draft channel 14 has a better effect on suppressing disordered cyclones and can further reduce energy loss.

[0040] Further optimize the above design, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, a filter device is installed at the bleed air channel 14 to control the cleanliness of the gas introduced into the pump chamber 11. A valve, such as a ball valve, butterfly valve, or solenoid valve, is also installed at the bleed air channel 14 to control its opening and closing as needed. In practical use, it can also be used to control the flow area of ​​the bleed air channel 14, achieving free control of the introduced gas flow rate to meet different vacuum requirements in various operating scenarios.

[0041] Example 2: Figure 5As shown, the difference between this embodiment and Embodiment 1 is that the bleed channel 14 is not connected to the atmospheric environment, but is connected to the suction channel 12 through the branch channel 16. Part of the gas in the suction channel 12 is introduced into the pump chamber 11 through the branch channel 16 and the bleed channel 14 to impact the disordered cyclone. Since the gas introduced into the pump chamber 11 comes entirely from the gas being processed, contamination from the external atmosphere or other gas sources is avoided, strictly ensuring the purity of the gas being processed. This is extremely important for applications such as chemical and semiconductor industries, which have strict requirements for the purity of process gases. Furthermore, the pumping capacity of the screw vacuum pump is entirely applied to the gas being processed, avoiding loss of effective pumping speed due to the introduction of additional gas sources. This makes the ultimate vacuum and operating vacuum of the screw vacuum pump essentially unaffected by the bleed measures, especially suitable for situations where the equivalent diameter of the bleed channel may be designed to be large, preventing a significant decrease in vacuum pump performance or failure due to improper bleed volume control. Meanwhile, the gas within the intake channel 12 already possesses a certain amount of kinetic energy. Utilizing this gas to impact the disordered cyclone produces a better disturbance and breaking effect than introducing relatively still air.

[0042] Example 3: Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, based on Embodiment 1, a sealing plate 3 is installed at one end of the pump chamber 11 near the suction channel 12. The shaft end of the screw rotor 2 passes through the sealing plate 3 and is connected to the bearing, which is mounted on the end cover 4. The end cover 4 and the sealing plate 3 together form a bearing chamber 15. A vent hole 41 is provided on the end cover 4 to connect the bearing chamber 15 with the atmospheric environment, so that a positive pressure environment higher than the low-pressure area of ​​the pump chamber 11 is formed in the bearing chamber 15. This ensures that the gas in the bearing chamber always flows towards the pump chamber 11 along the shaft end connection gap, forming an air barrier. The air barrier ensures that the airflow always flows towards the pump chamber 11 along the shaft end connection gap of the screw rotor 2, avoiding backflow and preventing external pollutants from entering the bearing chamber 15. It should be noted that the positive pressure environment is crucial. During the operation of the screw vacuum pump, the suction end of the pump chamber 11 is a low-pressure area, while the bearing chamber 15 is at standard atmospheric pressure connected to the atmospheric environment. The pressure difference direction always points from the bearing chamber 15 towards the pump chamber 11. This allows the airflow to flow only a small amount from the bearing chamber 15 through the shaft end gap into the pump chamber 11, effectively blocking the path of dust, oil mist and other pollutants in the treated gas to "reverse" invading the bearing chamber along the shaft end gap, protecting the bearing and lubrication system, and avoiding wear and scaling problems caused by the accumulation of pollutants.

[0043] Further optimize the above design, such as Figure 1 , Figure 2 and Figure 3As shown, the bearing chamber 15 is connected to the air intake channel 14, which is connected to the atmospheric environment or an external air source through the bearing chamber 15 and the vent 41. Reducing the machining length of the air intake channel 14 reduces machining costs.

[0044] Further optimize the above design, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the outer periphery of the sealing plate 3 is stepped; the air intake channel 14 is set along the outer side of the sealing plate 3 to reduce the processing difficulty.

[0045] Further optimize the above design, such as Figure 1 , Figure 2 and Figure 3 As shown, a filter device is installed at the vent 41 to filter the air entering the bearing chamber 15, preventing particulate matter from entering and adapting to working environments with poor atmospheric conditions. A valve, such as a ball valve, butterfly valve, or solenoid valve, is installed at the vent 41 to control the opening and closing of the vent as needed. In practical use, it can also be used to control the flow area of ​​the vent 41 and to coordinate the operation, shutdown, and cleaning of the vacuum pump during different periods by controlling the valve. Furthermore, in scenarios requiring high vacuum levels, the vacuum level of the vacuum pump can be increased by reducing the valve opening or even closing the valve.

[0046] Further optimize the above design, such as Figure 1 , Figure 2 and Figure 3 As shown, the pump body 1 contains two non-contact meshing screw rotors 2. The bearing chambers 15 corresponding to the two screw rotors 2 are interconnected, and their shaft ends are both connected to the same sealing plate 3. This structure can further improve the anti-fouling effect and operational stability.

[0047] refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the working process of this utility model is as follows:

[0048] The screw vacuum pump is started, and the screw rotor 2 rotates at high speed. The gas to be processed is drawn into the pump chamber 11 through the intake channel 12, and under the push of the screw rotor 2, it moves from the intake end of the pump chamber 11 to the exhaust end, where it is compressed, and finally discharged from the exhaust channel 13. During this process, an orderly, stable, and high-speed ordered cyclone is formed at the gap between the end of the screw rotor 2 and the end face of the intake end of the pump chamber 11.

[0049] Meanwhile, because the suction end of the pump chamber 11 corresponds to a low-pressure area with a pressure much lower than standard atmospheric pressure, the gas in the external atmosphere, under the influence of pressure difference, enters the bearing chamber 15 through the vent 41 on the end cover 4, forming a positive pressure environment. Subsequently, the gas splits into two paths: most of the gas is introduced into the area of ​​the pump chamber 11 prone to generating disordered cyclones through the duct 14; a very small portion of the gas flows slowly into the pump chamber 11 through the tiny gap between the rotor shaft end and the sealing plate. The gas introduced into the pump chamber 11 through the duct 14 directly impacts and disrupts the low-speed or reverse disordered cyclones, breaking them up and integrating them into the ordered cyclones of the main airflow, thereby eliminating the energy loss and contamination problems caused by eddies. The small amount of positive pressure airflow flowing from the bearing chamber to the pump chamber 11 acts as a barrier of gas, constantly preventing contaminants in the pump chamber 11 from re-entering the bearing chamber, achieving a dynamic sealing effect.

[0050] In summary, this invention solves two key problems simultaneously—energy consumption and dirt accumulation in the pump chamber due to disordered airflow and contaminant intrusion in the bearing area—by introducing external airflow to form an air barrier. The structure is simple and reliable, with significant anti-fouling effect, greatly improving the reliability and service life of the screw vacuum pump during continuous operation.

[0051] Finally, it should be noted that the above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A dirt-proof screw vacuum pump, comprising a pump body (1) and a screw rotor (2), wherein the pump body (1) is provided with a pump chamber (11) for accommodating the screw rotor (2); one end of the pump chamber (11) along the axial direction of the screw rotor (2) is an intake end, and the other end is an exhaust end; an intake channel (12) is provided at the intake end of the pump chamber (11), and an exhaust channel (13) is provided at the exhaust end of the pump chamber (11), characterized in that: The pump chamber (11) has an air intake channel (14) for connecting the pump chamber (11) with the air source or the external environment.

2. The anti-fouling screw vacuum pump according to claim 1, characterized in that: The opening of the air intake channel (14) in the pump chamber (11) is located on the side away from the air intake channel (12).

3. The anti-fouling screw vacuum pump according to claim 1, characterized in that: The air intake channel (14) is equipped with a filter device and a valve to control its opening and closing.

4. The anti-fouling screw vacuum pump according to claim 1, characterized in that: The gas source can be either a gas storage container or a gas generating device.

5. The anti-fouling screw vacuum pump according to claim 1, characterized in that: A branch channel (16) is provided between the air intake channel (12) and the air intake channel (14) to connect them.

6. The anti-fouling screw vacuum pump according to any one of claims 1 to 5, characterized in that: A sealing plate (3) is installed at one end of the pump chamber (11) near the air intake channel (12). The shaft end of the screw rotor (2) passes through the sealing plate (3) and is rotatably connected to a bearing. The bearing is installed on an end cover (4). The end cover (4) and the sealing plate (3) together form a bearing chamber. At least one vent hole (41) is provided through the end cover (4). The vent hole (41) connects the bearing chamber to the air source.

7. The anti-fouling screw vacuum pump according to claim 6, characterized in that: The bearing chamber is connected to the air venting channel.

8. The anti-fouling screw vacuum pump according to claim 7, characterized in that: The outer periphery of the sealing plate (3) is stepped; the air intake channel (14) is arranged along the outer side of the sealing plate (3).

9. The anti-fouling screw vacuum pump according to claim 6, characterized in that: The vent (41) is equipped with a filter and a valve to control its opening and closing.

10. The anti-fouling screw vacuum pump according to claim 6, characterized in that: The pump body (1) is equipped with two non-contact meshing screw rotors (2), the bearing chambers corresponding to the two screw rotors (2) are interconnected, and the shaft ends of the two screw rotors (2) are connected to the same sealing plate (3).

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