Vacuum pump with bearing pollution prevention function

Abstract

The utility model provides a vacuum pump with a bearing pollution prevention function, which comprises a shell, a stator, a rotor mounted on a bearing, an air inlet and an air outlet, and is characterized in that the vacuum pump comprises a bearing pollution prevention device, and the bearing pollution prevention device comprises a filter screen positioned at the air inlet and / or a sealing device close to the bearing. According to the vacuum pump, pollution particles can be effectively prevented from entering the bearing, especially the permanent magnet bearing, through the bearing anti-pollution device, the anti-corrosion performance of the permanent magnet bearing is improved, and therefore the service life of the turbo molecular pump in the severe environment is prolonged.

Description

Technical Field

[0001] The utility model relates to a vacuum pump, in particular to a vacuum pump capable of preventing bearing pollution. Background Art

[0002] The turbomolecular pump is a momentum transfer vacuum pump that uses a high-speed rotating impeller to transfer momentum to gas molecules, causing the gas to flow in a directional manner and then pump air. -3 Up to 10 -10 It can produce clean vacuum in the range of hPa. Because of its stable and reliable operation and good pumping efficiency under molecular flow state, it has become the mainstream equipment for obtaining clean high vacuum and ultra-high vacuum applications, and is widely used in scientific instruments and industrial production equipment.

[0003] Figure 1 A cross-sectional view of a conventional turbomolecular pump 10 of the prior art is disclosed. The turbomolecular pump 10 generally includes a cylindrical housing 11, a base 12 connected to the housing 11, a rotor 21 coaxially arranged with the housing 11, a motor 13 coaxially arranged with the rotor 21, and a stator 14 extending axially inward from the housing 11. The housing 11 provides a containment structure for the turbomolecular pump 10. The turbomolecular pump 10 also includes an air inlet connection port 15 penetrating the top of the housing 11. The air outlet port 16 penetrates the base 12 and is connected to a front-stage air pump (not shown). The motor 13 drives the rotor 21 to rotate around an axis. The rotor 21 can be supported in the housing by a mechanical bearing 17 and a permanent magnetic bearing 20, and the adjusting nut 22 is used to adjust the axial position of the inner ring of the permanent magnetic bearing. The mechanical bearing can also be replaced by a magnetic suspension bearing. The rotor 21 includes a plurality of rows of rotor blades 19 extending axially outward at each level from the central cylindrical portion of the rotor, and the central cylindrical portion of the rotor is connected to the motor 13. The stator 14 also includes a plurality of rows of blades 18 extending axially inwardly from the housing 11 at each level. The plurality of rows of stator blades 18 and the plurality of rows of rotor blades 19 are arranged alternately between the axial layers. The "first stage" of the pump is defined as the first row of rotor blades 19 and the first row of stator blades 18 at the inlet end of the pump. Each subsequent row of rotor blades 19 and the corresponding row of stator blades 18 constitute another stage, and the turbomolecular pump 10 generally has 3 to 10 stages. In addition, 1 to 2 mixing stages (such as Holvik stages) may be included to achieve higher exhaust pressures and higher inlet pressures (not shown).

[0004] The inlet end of the turbomolecular pump 10 is often in a relatively harsh environment, such as a highly acidic gas or a gas containing a large amount of particulate pollution. This will cause corrosion and blockage at some parts of the turbomolecular pump 10, resulting in failure of operation. In many cases, the permanent magnetic bearing located at the inlet end of the turbomolecular pump 10 is most susceptible to corrosion and blockage, thereby causing the permanent magnetic bearing to become stuck and fail, reducing the service life of the turbomolecular pump 10. In particular, the permanent magnetic bearing 20 of a conventional turbomolecular pump is located at the inlet of the turbomolecular pump, and the clearance between the rotor and stator of the permanent magnetic bearing 20 is generally small, which is prone to blockage and affects the service life.

[0005] Although many efforts have been made in the prior art to prevent dust from turbomolecular pumps, such as Chinese patent application No. 2022110582200, entitled A solution for a stator dust prevention component for a turbomolecular pump, the effect is not ideal. Utility Model Content

[0006] Therefore, in view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a vacuum pump that can effectively prevent contaminants from entering bearings, especially permanent magnetic bearings, and increase the corrosion resistance of permanent magnetic bearings, thereby increasing the life of the turbomolecular pump in harsh environments.

[0007] According to the utility model, a vacuum pump with a bearing contamination prevention function comprises a housing, a stator, a rotor mounted on a bearing, an air inlet and an air outlet, and is characterized in that the vacuum pump comprises a bearing contamination prevention device, and the bearing contamination prevention device comprises a filter located at the air inlet and / or a sealing device close to the bearing.

[0008] In the vacuum pump having the function of preventing bearing contamination as described above, the filter screen includes at least one radially outer groove.

[0009] In the vacuum pump having the function of preventing bearing contamination as described above, the grooves of the filter screen are circular or waist-shaped.

[0010] In the vacuum pump with the function of preventing bearing contamination as described above, the vacuum pump comprises an adjusting nut mounted on the bearing, and the sealing device comprises comb teeth located on the flange of the adjusting nut.

[0011] In the vacuum pump with the function of preventing bearing contamination as described above, the vacuum pump comprises an adjusting nut mounted on the bearing, and the sealing device comprises a spiral groove located on the flange of the adjusting nut.

[0012] In the vacuum pump having the bearing contamination prevention function as described above, the direction of the spiral groove is the same as the rotation direction of the first row of rotor blades.

[0013] In the vacuum pump having the bearing contamination prevention function as described above, the depth of the spiral groove increases as the diameter of the spiral groove increases.

[0014] In the vacuum pump with the function of preventing bearing contamination as described above, the vacuum pump includes a purge gas channel located on the housing, and the purge gas enters the housing through the purge gas channel to purge the bearing.

[0015] In the vacuum pump having the function of preventing bearing contamination as described above, the surface of the bearing includes a corrosion-resistant coating.

[0016] In the vacuum pump having the function of preventing bearing contamination as described above, the vacuum pump is a turbomolecular pump.

[0017] According to the vacuum pump of the utility model, the bearing anti-pollution device can effectively prevent pollutant particles from entering the bearing, especially the permanent magnetic bearing, and increase the anti-corrosion performance of the permanent magnetic bearing, thereby improving the life of the turbomolecular pump in harsh environments. The bearing anti-pollution device can be a filter screen at the air inlet and / or a sealing device close to the bearing. When the bearing anti-pollution device is a filter screen at the air inlet, the filter screen filters the incoming gas to prevent pollutant particles from entering the cavity of the vacuum pump. Providing radially outer grooves on the filter screen can ensure that the performance of the vacuum pump is not affected while filtering pollutant particles. When the bearing anti-pollution device is a sealing device close to the bearing, it can be directly modified on the existing adjusting nut without adding additional components. By providing a flange on the adjusting nut and providing a comb tooth or a spiral groove as a sealing component on the flange, not only can the purpose of preventing pollutant particles from entering the bearing be achieved, but also the structure is simple and very economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A simplified schematic diagram of a cross section of a turbomolecular pump in the prior art.

[0019] Figure 2 It is a cross-sectional schematic diagram of a turbomolecular pump according to the utility model.

[0020] Figure 3 It is a schematic cross-sectional view of a filter screen used as a bearing pollution prevention device according to the present invention.

[0021] Figure 4 It is a schematic diagram of a modified adjusting nut according to the utility model, wherein the modified adjusting nut has comb teeth.

[0022] Figure 5 It is a schematic diagram of a modified adjusting nut according to the utility model, wherein the modified adjusting nut has a spiral groove. DETAILED DESCRIPTION

[0023] Figure 21 is a cross-sectional view of a turbomolecular pump 30 according to an embodiment of the present invention. The structure of the turbomolecular pump 30 according to the present invention is substantially the same as that of the turbomolecular pump 10 of the prior art, the main difference being that the turbomolecular pump 30 according to the present invention has a bearing anti-pollution device. The following focuses on the structure and function of the bearing anti-pollution device. The description of other identical components can refer to the description of the background art. Figure 1 The record of the solution is incorporated as part of the technical solution of the utility model.

[0024] The first embodiment of the bearing anti-pollution device according to the present invention is a filter screen 31 arranged at the inlet of the turbomolecular pump 30. The filter screen 31 can prevent dust from entering the permanent magnetic bearing 20 at the pump axis and causing the bearing to become stuck.

[0025] Figure 3 An embodiment of the filter screen 31 according to the utility model is shown. Preferably, the filter screen is made of foam metal, and the filtering accuracy of the filter screen can be selected according to the size of the imported dust particles, preferably 50 microns. If there is a corrosive gas environment, the filter screen 31 is preferably made of anti-corrosion metal, such as stainless steel 304, 316L, etc. A bolt hole 42 can be opened at the center of the filter screen 31, and it is fixed to the housing 11 by bolts 32.

[0026] When the filtration accuracy of the filter 31 is high (i.e., the filter density is high), the filter 31 may generate a large gas resistance, which will cause the pump suction capacity to decrease, resulting in a decrease in the overall performance of the pump. In order to solve this problem, a groove 41 can be separated on the outside of the filter 31. The groove 41 can reduce the effect of the filter 31 on the pump suction capacity. Grooving the filter 31 reduces the gas resistance, so that the pump suction capacity meets the requirements.

[0027] Preferably, the groove 41 is arranged as radially outward as possible. Since the groove 41 is opened radially outward, even if some dust enters the cavity through the groove 41, most of it will flow backward along the flow channel at the blade and finally be discharged from the cavity without affecting the permanent magnet bearing 20. There can be one or more grooves 41. The shape of the groove 41 can be circular, waist-shaped or other shapes. The flow area of ​​the groove 41 is determined according to the suction capacity required by the pump, and the size and number of the grooves 41 are selected according to the flow area of ​​the groove. In other words, the size, shape and number of the grooves can be determined according to specific needs. Under the same flow area, such as Figure 3 The waist-shaped groove 41 shown is the best because it can be made narrower in radial direction. Specifically, the waist-shaped groove 41 includes a distal edge with a first radius at the center of the filter screen 31 and a proximal edge with a second radius at the center of the filter screen 31. The two side edges of the waist-shaped groove 41 intersect with the distal edge and the proximal edge respectively. Of course, Figure 3The shapes shown are examples only and other shapes may be used.

[0028] The second embodiment of the bearing anti-pollution device according to the utility model is a sealing device arranged near the permanent magnetic bearing 20. Preferably, the sealing device is arranged between the housing 11 and the first row of rotor blades 19. For easy installation, the sealing device can be integrated with the adjusting nut to form a modified adjusting nut 33. A flange can be arranged at the upper end of the conventional adjusting nut, and the sealing device is located on the flange.

[0029] Similar to the adjusting nut in the prior art, the modified adjusting nut 33 can adjust the axial position of the inner ring of the permanent magnetic bearing. The axial adjustment range is usually very small, generally not exceeding 0.2 mm. At the same time, the modified adjusting nut 33 has a sealing function, and the set sealing gap is greater than the axial adjustment range of the adjusting nut by more than 0.2 mm, ensuring that the adjusting nut 33 does not collide with the first row of rotor blades 19 under any conditions.

[0030] One embodiment of the sealing device is as follows Figure 4 The comb teeth 44 shown. A flange is provided at the upper end of the adjusting nut, and the comb teeth 44 are provided at the flange, thereby forming a modified adjusting nut 33 with a sealing function. The comb teeth 44 on the modified adjusting nut 33 cooperate with the corresponding structure (not shown) on the first row of rotor blades 19 to achieve the sealing function. Figure 4 The structure of the modified adjusting nut 33 and the cross-sectional schematic diagram along the BB direction are shown. The cross-sectional schematic diagram shows an example of the specific structure of the comb teeth 44. Preferably, the distance between two adjacent teeth of the comb teeth 44 is the same, and the height of the teeth is the same.

[0031] Another embodiment of the sealing device is as follows Figure 5 The spiral groove 45 shown is arranged on the modified adjustment nut 33. The direction of the spiral groove 45 is the same as the rotation direction of the first row of rotor blades 19. Preferably, the depth of the spiral groove 45 can increase as the diameter increases. The spiral groove 45 on the modified adjustment nut 33 cooperates with the corresponding structure (not shown) on the first row of rotor blades 19 to achieve a sealing function. Figure 5 The structure of the modified adjusting nut 33 and the cross-sectional schematic diagram along the AA direction are shown. The cross-sectional schematic diagram shows an example of the specific structure of the spiral groove 45. Figure 5 It can be seen from the schematic diagram that on the flange of the modified adjusting nut 33, the depth and width of the spiral groove 45 at the distal end are greater than the depth and width of the spiral groove 45 at the proximal end.

[0032] Although Figure 2 The turbomolecular pump 30 also has a first embodiment of a bearing anti-contamination device ( Figure 3The filter screen 31 shown) and the second embodiment of the bearing anti-pollution device ( Figure 4 and Figure 5 The sealing device shown in the figure) can be used, but any one of them can be selected according to actual needs.

[0033] In order to better prevent corrosive gas or dust from being deposited on the permanent magnetic bearing 20, a purge gas channel 34 can be provided on the housing 11. The purge gas is introduced through the purge gas channel 34 to purge the permanent magnetic bearing 20 when the turbomolecular pump 30 is stopped. The gas can be nitrogen, argon or other inert gases. The purge gas channel 34 is provided on the housing 11, and a flow valve can be provided to control the flow of the purge gas.

[0034] In the turbomolecular pump 30 according to the present invention, if the gas at the inlet is corrosive, a corrosion-resistant coating, such as a nickel-copper-nickel coating or an epoxy resin coating, can be electroplated or sprayed on the surface of the permanent magnetic bearing 20 to prevent the gas from corroding the permanent magnetic bearing 20.

[0035] The above embodiment of the present invention is described by taking the turbomolecular pump 30 as an example, but the present invention is also applicable to other types of vacuum pumps.

[0036] In this specification, the specific features, mechanisms, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without contradicting each other.

[0037] The above description is only an implementation example of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A vacuum pump with a function of preventing bearing contamination, comprising a housing, a stator, a rotor mounted on a bearing, an air inlet and an air outlet, characterized in that The vacuum pump includes a bearing anti-pollution device, The bearing anti-pollution device comprises a filter located at the air inlet and / or a sealing device close to the bearing.

2. The vacuum pump with the function of preventing bearing contamination according to claim 1, characterized in that: The screen includes at least one radially outer groove.

3. The vacuum pump with the function of preventing bearing contamination according to claim 2, characterized in that: The groove of the filter screen is circular or waist-shaped.

4. The vacuum pump with the function of preventing bearing contamination according to claim 1, characterized in that: The vacuum pump comprises an adjusting nut mounted on a bearing, and the sealing device comprises comb teeth located on a flange of the adjusting nut.

5. The vacuum pump with the function of preventing bearing contamination according to claim 1, characterized in that: The vacuum pump comprises an adjusting nut mounted on a bearing, and the sealing device comprises a spiral groove on a flange of the adjusting nut.

6. The vacuum pump with the function of preventing bearing contamination according to claim 5, characterized in that: The direction of the spiral groove is the same as the rotation direction of the first row of rotor blades.

7. The vacuum pump with the function of preventing bearing contamination according to claim 6, characterized in that: The depth of the spiral groove increases as the diameter of the spiral groove increases.

8. The vacuum pump with the function of preventing bearing contamination according to any one of claims 1 to 7, characterized in that: The vacuum pump comprises a purge gas channel on the housing, through which the purge gas enters the housing to purge the bearing.

9. The vacuum pump with the function of preventing bearing contamination according to any one of claims 1 to 7, characterized in that: The surface of the bearing includes a corrosion resistant coating.

10. The vacuum pump with the function of preventing bearing contamination according to any one of claims 1 to 7, characterized in that: The vacuum pump is a turbomolecular pump.

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