Molecular pump

Abstract

The invention provides a molecular pump. The molecular pump comprises a shell 1, a magnetic bearing center shaft assembly, a main shaft assembly, a traction assembly and a base 20. The magnetic bearing central shaft assembly comprises a magnetic bearing central shaft 2, an adjusting ring 6 and a permanent magnet bearing; the main shaft assembly is assembled on the shell 1 through a magnetic bearing central shaft 2; the traction assembly is connected with the main shaft assembly, and the base 20 is connected with the traction assembly; the permanent magnet bearing is sleeved on the magnetic bearing central shaft 2; wherein the permanent magnet bearing comprises an inner magnetic ring 3 and an outer magnetic ring 4, and the inner magnetic ring 3 is mounted on the magnetic bearing central shaft 2; an adjusting ring 6 is arranged on the end face of the inner magnetic ring 3 away from the spindle; the outer magnetic ring 4 is mounted in a groove in the upper part of a main shaft 5 of the main shaft assembly; the non-contact permanent magnet bearing is used as a constraint support at the high vacuum part of the upper half part of the main shaft assembly, and is free of abrasion and high in reliability; and the axial vibration damping and the radial vibration damping are arranged at the mechanical bearing, so that the operation vibration is effectively reduced, and meanwhile, the assembly accumulated error is made up.

Description

Technical Field

[0001] The invention belongs to the field of vacuum obtaining equipment, and in particular relates to a molecular pump. Background Art

[0002] As a mainstream vacuum obtaining equipment, molecular pumps can be used in scientific research, new energy, semiconductors, aerospace and other fields. When used in this field, there are often extremely high requirements for pumping efficiency, cleanliness, vacuum and vibration. In the past, molecular pumps had a series of problems such as general pumping performance, insufficient rotor rigidity, poor dynamic characteristics, mechanical bearing grease volatilization, poor reliability and life, overheating, etc., which gradually failed to meet the needs of industry use.

[0003] In addition, the molecular pump in the prior art has the technical problems of obvious vibration leading to large cumulative assembly error and poor heat dissipation. Summary of the invention

[0004] In view of the defects in the prior art, an object of the present invention is to provide a molecular pump.

[0005] The molecular pump provided by the present invention comprises: a housing 1, a magnetic bearing central shaft assembly, a main shaft assembly, a traction assembly, and a base 20;

[0006] The magnetic bearing central axis assembly comprises: a magnetic bearing central axis 2, an adjustment ring 6, and a permanent magnetic bearing;

[0007] The spindle assembly is assembled on the housing 1 through the magnetic bearing central axis 2; the traction assembly is connected to the spindle assembly, and the base 20 is connected to the traction assembly;

[0008] The permanent magnetic bearing is sleeved on the central axis 2 of the magnetic bearing;

[0009] The permanent magnetic bearing comprises an inner magnetic ring 3 and an outer magnetic ring 4.

[0010] The inner magnetic ring 3 is mounted on the central axis 2 of the magnetic bearing; an adjustment ring 6 is provided on the end surface of the inner magnetic ring 3 away from the main axis;

[0011] The outer magnetic ring 4 is installed in a groove on a main shaft 5 of the main shaft assembly.

[0012] Preferably, the main shaft assembly comprises: moving blades 7 and stationary blades 8;

[0013] The number of the moving blades 7 and the stationary blades 8 is multiple;

[0014] The plurality of moving blades 7 are sleeved on the main shaft 5 at intervals;

[0015] The plurality of stationary blades 8 are fixedly arranged on the housing 1;

[0016] The plurality of moving blades 7 and the plurality of stationary blades 8 on the main shaft assembly are staggeredly arranged on the upper part of the main shaft, thereby forming a multi-stage turbine; and the blade angles of the moving blades 7 and the stationary blades 8 are in opposite circumferential directions.

[0017] Preferably, a radially extending platform is provided in the middle portion of the main shaft 5 , and a plurality of circular grooves are provided on the platform at a portion close to the axis of the main shaft 5 ; the plurality of circular grooves are meshedly connected with the air blocking structure 9 .

[0018] Preferably, the traction assembly comprises: a rotor 17 sleeved on the lower end of the platform of the main shaft 5, a stator 16, a first carbon fiber tube 10, a second fiber tube 11, a first spiral member 12, a second spiral member 13, and a third spiral member 14;

[0019] The stator 16 is connected to the first spiral member 12;

[0020] The main shaft 5 is radially sleeved with a first spiral member 12, a second fiber tube 11, a second spiral member 13, a first carbon fiber tube 10, and a third spiral member 14 in sequence;

[0021] One end of the first spiral member 12 is connected to the air blocking structure 9, and the other end of the first spiral member 12 is connected to the base 20; the second fiber tube 11 and the first carbon fiber tube 10 are both fixed on the platform set on the main shaft, and there is an air path for airflow between the second spiral member 13 and the platform set on the main shaft, and the second spiral member 13 is fixedly connected to the base 20; the end of the platform is connected to the first carbon fiber tube 10 on the traction assembly;

[0022] One end of the third spiral member 14 is connected to the lower end of the housing 1 , and the other end of the third spiral member 14 is connected to the base 20 .

[0023] Preferably, the first carbon fiber tube 10 and the second fiber tube 11 are both smooth annular;

[0024] The first spiral component 12 , the second spiral component 13 , and the third spiral component 14 are provided with spiral grooves.

[0025] Preferably, the traction assembly further comprises: a mechanical bearing 19, a bearing seat 18, an oil-cotton assembly 23 and a sealing plate 24;

[0026] The lower end of the main shaft 5 is sleeved with a mechanical bearing 19 and a bearing seat 18 in sequence outwardly along the axial direction; the bearing seat 18 is used to support the mechanical bearing 19;

[0027] The oil-cotton assembly 23 is arranged between the bottom of the mechanical bearing 19 and the base 20 , and the sealing plate 24 is arranged below the oil-cotton assembly 23 .

[0028] Preferably, the bearing seat 18 is provided with grooves in the axial direction and radial direction respectively;

[0029] The grooves of the bearing seat 18 are respectively provided with axial vibration damping 21 and radial vibration damping 22; wherein the axial vibration damping 21 is arranged in the axial groove of the mechanical bearing 19 and the bearing seat 18; and the radial vibration damping 22 is arranged in the radial groove of the mechanical bearing 19 and the bearing seat 18.

[0030] Preferably, the base 20 is also provided with a water cooling structure 25 and an air cooling structure 26.

[0031] The water cooling structure 25 is arranged in a groove opened along the circumferential direction of the base 20;

[0032] The air cooling structure 26 is disposed on the lower end surface of the base 20 .

[0033] Preferably, a step structure is provided at the connection between the main shaft 5 and the plurality of moving blades 7 , wherein a portion of the moving blades 7 is arranged at an upper portion of the step structure, and another portion of the moving blades 7 is arranged at a lower portion of the step structure.

[0034] Preferably, a driver 15 is further included, wherein the driver 15 is installed outside the housing 1 and is electrically connected to the stator 16 .

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The invention optimizes the design of the spindle assembly and the spindle, is lightweight and high-strength, is integrally formed, has strong processability, and is high in precision; the non-contact permanent magnetic bearing is used as a constraint support at the high vacuum of the upper half of the spindle assembly, is wear-free, and has high reliability;

[0037] The present invention provides axial vibration damping and radial vibration damping at the mechanical bearing to effectively reduce the running vibration and compensate for the cumulative assembly error.

[0038] The present invention is designed with an air-blocking structure to dynamically isolate the space on the motor side, thereby providing a more efficient and cleaner high-vacuum environment; a water cooling structure and an air cooling structure are provided to effectively dissipate heat, extend the life of the bearing and the motor, and further enhance reliability; the oil-cotton assembly at the mechanical bearing is easy to disassemble, making repair and maintenance convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0040] Figure 1 It is a schematic diagram of the overall structure of the molecular pump of the present invention;

[0041] Figure 2It is a schematic diagram of the cooperation between the base and the second screw member 13 provided by the present invention;

[0042] The figure shows

[0043] Housing 1 First carbon fiber tube 10 Mechanical bearing 19

[0044] Magnetic bearing central axis 2 Second carbon fiber tube 11 Base 20

[0045] Inner magnetic ring 3 First spiral element 12 Axial vibration damping 21

[0046] Outer magnetic ring 4 Second spiral element 13 Radial vibration damping 22

[0047] Main shaft 5 Third spiral 14 Oil cotton component 23

[0048] Adjustment ring 6 Driver 15 Sealing plate 24

[0049] Moving blade 7 Stator 16 Water cooling structure 25

[0050] Stationary blades 8 Rotor 17 Air cooling structure 26

[0051] Air blocking structure 9 Bearing seat 18 DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0053] The present invention provides a molecular pump, comprising a housing 1, a magnetic bearing central shaft assembly, a main shaft assembly, a traction assembly, a base assembly and a controller;

[0054] The main shaft assembly is interference-fitted on the housing 1 through the magnetic bearing center shaft 2 on the magnetic bearing center shaft assembly; the traction assembly is connected to the main shaft assembly, and the base assembly is connected to the traction assembly;

[0055] The magnetic bearing center shaft assembly includes: a magnetic bearing center shaft 2, an adjustment ring 6, a permanent magnetic bearing

[0056] The permanent magnetic bearing is sleeved on the central axis 2 of the magnetic bearing, wherein the permanent magnetic bearing comprises an inner magnetic ring 3 and an outer magnetic ring 4.

[0057] The number of the inner magnetic ring 3 and the outer magnetic ring 4 is one or more, and the inner magnetic ring 3 is mounted on the central axis 2 of the magnetic bearing; an adjustment ring 6 is arranged on the end surface of the inner magnetic ring 3 away from the main axis;

[0058] The outer magnetic ring 4 is installed in the groove of the main shaft 5 with interference fit. The outer magnetic ring 4 has no contact with the inner magnetic ring 3 and uniformly restrains and supports the main shaft assembly through magnetic resistance, so that the main shaft assembly is free of wear and has high cleanliness.

[0059] The main shaft assembly includes: a main shaft 5, moving blades 7 and stationary blades 8;

[0060] The main shaft 5 is made of aviation aluminum alloy, with small structural inertia and high stability. One end is rotatably connected to the permanent magnetic bearing, and the other end is mounted on the mechanical bearing 19;

[0061] The outer magnetic ring 4, the main shaft 5, and the moving blades 7 are sequentially assembled on the main shaft assembly from the inside to the outside by using small interference fit heat sets.

[0062] There are multiple moving blades 7 and multiple stationary blades 8, and the multiple moving blades 7 are sleeved on the main shaft 5 at intervals; the multiple stationary blades 8 are fixedly arranged on the casing 1; the multiple moving blades 7 and the multiple stationary blades 8 on the rotor assembly are staggered on the upper part of the main shaft; thereby forming a multi-stage turbine; and the blade angles of the moving blades 7 and the stationary blades 8 are opposite in circumferential direction.

[0063] The main shaft is integrally formed 5, and a total of 6 shrink-fit fitting surfaces thereon are clamped and processed in place at one time to ensure accuracy; the fitting surfaces for installing multiple moving blades 7 are designed with two sizes to form a step structure to enhance its processability.

[0064] Specifically, a step structure is provided at the connection between the main shaft 5 and the plurality of moving blades 7, wherein a part of the moving blades 7 is provided at the upper part of the step structure, and another part of the moving blades 7 is provided at the lower part of the step structure.

[0065] The stationary blade 8 is formed by molding, and is provided with a reinforcing groove on the inner side and a rim on the outer side to increase rigidity and be used for positioning.

[0066] A radially extending platform is provided in the middle of the main shaft 5, and a plurality of circular grooves are provided on the platform near the center line of the main shaft 5; the plurality of circular grooves are meshedly connected with the air blocking structure 9;

[0067] During the dynamic operation of the rotor, the motor side is isolated from the high vacuum side of the exhaust to ensure the exhaust efficiency and cleanliness;

[0068] The end of the platform is connected to the first carbon fiber tube 10 on the traction assembly;

[0069] The traction assembly includes: a rotor 17 and a stator 16 sleeved on the lower end of the platform of the main shaft 5;

[0070] The stator 16 is connected to the first spiral member 12;

[0071] The main shaft 5 is radially sleeved with a first spiral member 12, a second fiber tube 11, a second spiral member 13, a first carbon fiber tube 10, and a third spiral member 14 in sequence; by sequentially arranging, a three-stage compression traction stage is formed;

[0072] The first carbon fiber tube 10 and the second fiber tube 11 are both in the shape of smooth annuli. The first carbon fiber tube 10 and the second fiber tube 11 are sequentially assembled on the assembled traction assembly from the inside to the outside by using small interference fit heat-fitting.

[0073] The first spiral member 12, the second spiral member 13 and the third spiral member 14 are provided with spiral grooves along the gas path. The gas path of the traction stage is long and the compression effect is significant.

[0074] Further, one end of the first spiral member 12 is connected to the air blocking structure 9, and the other end is connected to the base 20 on the base assembly; the second fiber tube 11 and the first carbon fiber tube 10 are both fixed on the platform of the main shaft, and there is an air path for airflow between the second spiral member 13 and the platform set on the main shaft, and the second spiral member 13 is fixedly connected to the base 20;

[0075] One end of the third spiral member 14 is connected to the lower end of the housing 1, and the other end is connected to the base 20 on the base assembly;

[0076] The driver 15 is fastened outside the pump, and a seal is provided to ensure that the motor is driven under vacuum. The driver 15 controls the motor stator 16 to magnetically pull the motor rotor 17 to rotate at high speed; the driver 15 is installed outside the housing 1 and is electrically connected to the stator 16.

[0077] The stator 16 is an ultra-high-speed brushless permanent magnet motor; the rotor 17 is a permanent magnet.

[0078] The lower end of the main shaft 5 is provided with a mechanical bearing 19 and a bearing seat 18 in sequence outwardly along the axial direction; the bearing seat 18 is used to support the mechanical bearing 19;

[0079] Furthermore, the bearing seat 18 is provided with an axial vibration damping 21 and a radial vibration damping 22, which can effectively reduce the running vibration and compensate for the cumulative assembly error;

[0080] The grooves of the bearing seat 18 are respectively provided with an axial vibration damping damper 21 and a radial vibration damping damper 22; wherein the axial vibration damping damper 21 is provided in the grooves in the axial direction of the mechanical bearing 19 and the bearing seat 18; and the radial vibration damping damper 22 is provided in the grooves in the radial direction of the mechanical bearing 19 and the bearing seat 18.

[0081] The base assembly is also provided with an oil cotton assembly 23 and a sealing plate 24;

[0082] The oil cotton assembly 23 is composed of multiple layers of oil cotton, and is arranged between the bottom of the mechanical bearing 19 and the base 20, and can store a certain amount of lubricating oil for daily use of the bearing; the oil cotton assembly 23 is easy to disassemble and convenient for maintenance. The sealing plate 24 is used for sealing, and the sealing plate 24 is arranged below the oil cotton assembly 23.

[0083] The base 20 is provided with a water cooling structure 25 and an air cooling structure 26 , which can effectively dissipate heat and improve life and reliability; wherein the water cooling structure 25 is arranged in a groove opened along the circumferential direction of the base 20; and the air cooling structure 26 is arranged on the lower end surface of the base 20.

[0084] The base 20 and the second spiral member 13 are heat-fitted by interference fit after processing, which reduces the process difficulty while ensuring accuracy. A circle of rectangular grooves is provided on the outer cylindrical surface of the base to increase the air cooling effect. The rectangular grooves are formed in one step using a saw blade milling cutter.

[0085] Working principle:

[0086] The working state of the molecular pump is as follows: it is supported by the non-contact permanent magnetic bearing composed of the inner magnetic ring 3 and the outer magnetic ring 4 and the constraint of the mechanical bearing; the turbine stage is composed of the moving blades 7 and the stationary blades 8, and the traction stage is composed of the first spiral 12, the second fiber tube 11, the second spiral 13, the first carbon fiber tube 10, and the third spiral 14; the driver drives the motor stator magnetic traction rotor assembly to rotate at high speed; under the high-speed rotation of the rotor assembly, the gas molecules enter from the air inlet, enter the traction stage through the directional impact movement of the moving blades and the stationary blades in the turbine stage, and are pulled by the high-speed rotating carbon fiber tube and the directional spiral groove in the traction stage, and are finally discharged from the exhaust port after three-stage compression. In the process, the rotor assembly as a moving part is optimized in structure and process, and has strong operation stability and high reliability; at the same time, during the air extraction process, the air blocking mechanism 9 dynamically isolates the motor side to prevent the oil and gas of the mechanical bearing from entering the high vacuum side and causing pollution. There is no contact and no loss at the permanent magnetic bearings, and the axial vibration damping and radial vibration damping work together at the mechanical bearings to ensure stable operation of the bearings; the water cooling structure and the air cooling structure ensure good heat dissipation of the bearings and motors, further extending the service life and reliability.

[0087] The molecular pump provided by the present invention has a main shaft assembly and an optimized main shaft design, which are light and high-strength, integrally formed, strong in processability and high in precision; a non-contact permanent magnetic bearing is used as a constraint support at the high vacuum of the upper half of the rotor assembly, which is wear-free and highly reliable; an axial vibration damping and a radial vibration damping are provided at the mechanical bearing to effectively reduce the running vibration and compensate for the cumulative assembly error; an air blocking structure is designed to dynamically isolate the space on the motor side, which can provide a more efficient and cleaner high vacuum environment; a water cooling structure and an air cooling structure are provided to effectively dissipate heat, extend the service life of the bearing and the motor, and further enhance reliability; the oil cotton assembly at the mechanical bearing is easy to disassemble and convenient for repair and maintenance.

[0088] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0089] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A molecular pump, characterized in that: include: It includes a housing 1, a magnetic bearing central shaft assembly, a main shaft assembly, a traction assembly, and a base 20; The magnetic bearing central axis assembly comprises: a magnetic bearing central axis 2, an adjustment ring 6, and a permanent magnetic bearing; The spindle assembly is assembled on the housing 1 through the magnetic bearing central axis 2; the traction assembly is connected to the spindle assembly, and the base 20 is connected to the traction assembly; The permanent magnetic bearing is sleeved on the central axis 2 of the magnetic bearing; The permanent magnetic bearing comprises an inner magnetic ring 3 and an outer magnetic ring 4. The inner magnetic ring 3 is mounted on the central axis 2 of the magnetic bearing; an adjustment ring 6 is provided on the end surface of the inner magnetic ring 3 away from the main axis; The outer magnetic ring 4 is installed in a groove on a main shaft 5 of the main shaft assembly.

2. The molecular pump according to claim 1, characterized in that: The main shaft assembly includes: moving blades 7 and stationary blades 8; The number of the moving blades 7 and the stationary blades 8 is multiple; The plurality of moving blades 7 are sleeved on the main shaft 5 at intervals; The plurality of stationary blades 8 are fixedly arranged on the housing 1; The plurality of moving blades 7 and the plurality of stationary blades 8 on the main shaft assembly are staggeredly arranged on the upper part of the main shaft, thereby forming a multi-stage turbine; and the blade angles of the moving blades 7 and the stationary blades 8 are in opposite circumferential directions.

3. The molecular pump according to claim 1, characterized in that: A radially extending platform is provided in the middle of the main shaft 5 , and a plurality of circular grooves are provided on the platform near the axis of the main shaft 5 ; the plurality of circular grooves are meshedly connected with the air blocking structure 9 .

4. The molecular pump according to claim 3, characterized in that: The traction assembly includes: a rotor 17 sleeved on the lower end of the platform of the main shaft 5, a stator 16, a first carbon fiber tube 10, a second fiber tube 11, a first spiral member 12, a second spiral member 13, and a third spiral member 14; The stator 16 is connected to the first spiral member 12; The main shaft 5 is radially sleeved with a first spiral member 12, a second fiber tube 11, a second spiral member 13, a first carbon fiber tube 10, and a third spiral member 14 in sequence; One end of the first spiral member 12 is connected to the air blocking structure 9, and the other end of the first spiral member 12 is connected to the base 20; the second fiber tube 11 and the first carbon fiber tube 10 are both fixed on the platform set on the main shaft, and there is an air path for airflow between the second spiral member 13 and the platform set on the main shaft, and the second spiral member 13 is fixedly connected to the base 20; the end of the platform is connected to the first carbon fiber tube 10 on the traction assembly; One end of the third spiral member 14 is connected to the lower end of the housing 1 , and the other end of the third spiral member 14 is connected to the base 20 .

5. The molecular pump according to claim 4, characterized in that: The first carbon fiber tube 10 and the second fiber tube 11 are both smooth circular ring-shaped; The first spiral component 12 , the second spiral component 13 , and the third spiral component 14 are provided with spiral grooves.

6. The molecular pump according to claim 1, characterized in that: The traction assembly also includes: a mechanical bearing 19, a bearing seat 18, an oil-cotton assembly 23 and a sealing plate 24; The lower end of the main shaft 5 is sleeved with a mechanical bearing 19 and a bearing seat 18 in sequence outwardly along the axial direction; the bearing seat 18 is used to support the mechanical bearing 19; The oil-cotton assembly 23 is arranged between the bottom of the mechanical bearing 19 and the base 20 , and the sealing plate 24 is arranged below the oil-cotton assembly 23 .

7. The molecular pump according to claim 6, characterized in that: The bearing seat 18 is provided with grooves in the axial direction and radial direction respectively; The grooves of the bearing seat 18 are respectively provided with axial vibration damping 21 and radial vibration damping 22; wherein the axial vibration damping 21 is arranged in the axial groove between the mechanical bearing 19 and the bearing seat 18; and the radial vibration damping 22 is arranged in the radial groove between the mechanical bearing 19 and the bearing seat 18.

8. The molecular pump according to claim 1, characterized in that: The base 20 is also provided with a water cooling structure 25 and an air cooling structure 26. The water cooling structure 25 is arranged in a groove opened along the circumferential direction of the base 20; The air cooling structure 26 is disposed on the lower end surface of the base 20 .

9. The molecular pump according to claim 2, characterized in that: A step structure is provided at the connection between the main shaft 5 and the plurality of moving blades 7 , wherein a part of the moving blades 7 is arranged at the upper part of the step structure, and another part of the moving blades 7 is arranged at the lower part of the step structure.

10. The molecular pump according to claim 1, characterized in that: The housing 1 further comprises a driver 15 which is mounted outside the housing 1 and is electrically connected to the stator 16 .

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