Rotor assembly for molecular pump and molecular pump

Abstract

The utility model relates to a molecular pump, in particular to a rotor assembly for the molecular pump and the molecular pump, the rotor assembly comprises a rotating shaft, a movable impeller and a positioning part, the rotating shaft is in the axial direction of the rotating shaft, and the rotating shaft is provided with a first end and a second end; the movable impeller comprises a body part and blades arranged on the body part, the body part is connected to the first end, the body part is provided with a plurality of first balance weight areas, and the first balance weight areas are arranged in the circumferential direction of the rotating shaft at intervals; the positioning part is arranged at the second end to limit the rotating shaft, the positioning part is provided with a plurality of second counterweight areas, and the plurality of second counterweight areas are arranged at intervals in the circumferential direction of the rotating shaft. The technical effect that the dynamic balance counterweight structure is arranged on the rotor assembly to improve the dynamic balance of the molecular pump is achieved.

Description

Technical Field

[0001] This application relates to molecular pumps, and more particularly to a rotor assembly for a molecular pump and a molecular pump. Background Technology

[0002] The dynamic balance of the shaft assembly in a turbomolecular pump affects its safety performance and lifespan. Poor dynamic balance can cause vibration, bearing wear, and reduced pump safety and lifespan. Therefore, a dynamic balancing test is performed on the shaft assembly before turbomolecular pump assembly; this is called offline dynamic balancing. After assembly, the shaft assembly and impeller are joined together, requiring a dynamic balancing test on both components. This test is performed inside the turbomolecular pump and is called online dynamic balancing. Online dynamic balancing uses an oscilloscope to identify imbalance points and applies weights to reduce the peak-to-peak displacement to within the required range. To meet the dynamic balancing requirements of the turbomolecular pump, a dynamic balancing counterweight structure is necessary. Utility Model Content

[0003] This application provides a rotor assembly and a molecular pump for a molecular pump, which solves the technical problem of how to set a dynamic balance counterweight structure on the rotor assembly in the dynamic balance test of the molecular pump, and achieves the technical effect of improving the dynamic balance of the molecular pump by setting a dynamic balance counterweight structure on the rotor assembly.

[0004] To achieve the above objectives, the main technical solutions adopted in this application include:

[0005] In a first aspect, embodiments of this application provide a rotor assembly for a molecular pump, including a rotating shaft, a moving impeller, and a positioning part. The rotating shaft is axially aligned and has a first end and a second end. The moving impeller includes a body portion and blades disposed on the body portion. The body portion is connected to the first end and has a plurality of first counterweight areas, which are spaced apart circumferentially along the rotating shaft. The positioning part is disposed at the second end to limit the rotation shaft. The positioning part has a plurality of second counterweight areas, which are spaced apart circumferentially along the rotating shaft.

[0006] The rotor assembly for a molecular pump proposed in this application has a positioning part and a moving impeller respectively located on opposite sides of a rotating shaft. The positioning part is used to axially limit the rotating shaft and prevent axial displacement. Multiple first counterweight areas are provided on the main body of the moving impeller, and multiple second counterweight areas are provided on the positioning part, achieving the purpose of setting counterweight points for dynamic balance testing on both sides of the rotor assembly. During dynamic balance testing, the unbalanced position and unbalanced mass are found by using an oscilloscope for trial weight. By increasing the weight in the first and / or second counterweight areas, the rotor assembly gradually reaches a balanced state, thereby reducing vibration and wear caused by imbalance in the rotor assembly of the molecular pump during operation, and thus improving the safety of the molecular pump.

[0007] Optionally, the positioning part includes a spacer ring and a fastener, the spacer ring being sleeved on the second end, and the fastener cooperating with the end of the second end along the axial direction of the rotating shaft to press the spacer ring against the second end; wherein, a plurality of second counterweight areas are disposed on the spacer ring or the fastener.

[0008] Spacers are used to axially limit the rotation shaft, and fasteners are used to press the spacers together. Multiple second counterweight zones are provided on the spacers or fasteners, so that the second end of the rotor assembly has a counterweight point. By increasing the weight of the first and / or second counterweight zones, the dynamic balance of the molecular pump rotor assembly is adjusted, thereby improving the dynamic balance of the molecular pump rotor assembly.

[0009] Optionally, the fastener includes a nut and a screw connected to each other, the screw being threaded onto the end of the second end, and the nut abutting against the spacer ring along the axial direction of the rotating shaft; the second counterweight area is disposed on the outer peripheral surface of the spacer ring or the outer peripheral surface of the nut.

[0010] The fastener abuts against the spacer, positioning the spacer at the second end of the shaft and preventing displacement on the shaft. The second counterweight area is located on the outer circumferential surface of the spacer or the outer circumferential surface of the nut, facilitating the counterweighting of the rotor assembly during dynamic balancing tests of the molecular pump.

[0011] Optionally, along the axial direction of the rotating shaft, the second end includes a first segment and a second segment, the second segment being farther away from the first end than the first segment; the outer peripheral surface of the second segment includes a first plane and a second plane parallel to each other, the distance between the first plane and the second plane being less than the outer diameter of the first segment, so as to form a first stepped surface on the second end, and along the axial direction of the rotating shaft, the spacer abuts against the first stepped surface.

[0012] The second end of the rotating shaft has a first plane, a second plane, and a first stepped surface. The inner circumferential surface of the spacer abuts against the first and second planes. The side of the spacer facing the impeller body abuts against the first stepped surface, and the side of the spacer away from the impeller body abuts against a fastener. When the rotating shaft rotates, the spacer rotates synchronously with the rotating shaft, and the spacer abutting against the first stepped surface of the rotating shaft can restrict the axial displacement of the rotating shaft.

[0013] Optionally, the first counterweight area is constructed as a first threaded hole, and the second counterweight area is constructed as a second threaded hole.

[0014] A first threaded hole is machined on the outer peripheral surface of the main body, and a second threaded hole is machined on the outer peripheral surface of the spacer or fastener. When performing dynamic balancing tests on the molecular pump, if the rotor assembly is unbalanced, the weight of the rotor assembly can be adjusted to a balanced state by adding counterweight screws through the first threaded hole and / or the second threaded hole.

[0015] Secondly, embodiments of this application provide a molecular pump, including a housing and a rotor assembly as described in any of the above embodiments, wherein the housing has a receiving space and the rotor assembly is disposed in the receiving space.

[0016] In the dynamic balancing test of the molecular pump, the unbalanced position and unbalanced mass are found by using an oscilloscope to test the weight. By increasing the weight in the first and / or second counterweight areas, the rotor assembly is gradually brought into a balanced state, thereby reducing the vibration and wear caused by the unbalance of the rotor assembly of the molecular pump during operation, and thus improving the safety of the molecular pump.

[0017] Optionally, the housing has an air inlet and an exhaust outlet, and the molecular pump further includes a carbon fiber traction cylinder disposed inside the housing. The carbon fiber traction cylinder is adapted to guide the airflow entering through the air inlet to the exhaust outlet. The carbon fiber traction cylinder acts as an airflow guide in the molecular pump and will not expand or deform due to the high-speed rotation of the rotor assembly. Furthermore, the carbon fiber traction cylinder is lightweight, which can reduce the load on the rotor assembly.

[0018] Optionally, the molecular pump further includes a base, the base including a bottom wall and a peripheral wall surrounding the periphery of the bottom wall, the bottom wall and the peripheral wall defining the receiving space; the bottom wall corresponds to the axial end of the rotor assembly, and the peripheral wall is provided with a first through hole, the first through hole penetrating the peripheral wall along the thickness direction of the peripheral wall.

[0019] A first through hole is set on the base. During the dynamic balance test of the molecular pump, the second counterweight area can be counterweighted through the first through hole to adjust the rotor assembly to a balanced state.

[0020] Optionally, the second counterweight area is constructed as a second threaded hole, and the axis of the first through hole and the axis of the second threaded hole are on the same plane.

[0021] The first through hole is connected to the second threaded hole. By passing a screwdriver through the first through hole and then placing the counterweight screw in the second threaded hole, the entire counterweight process of the dynamic balancing test is convenient and quick.

[0022] Optionally, the diameter of the first through hole is larger than the diameter of the second threaded hole; there are multiple first through holes, and the number of first through holes is less than the number of second counterweight areas.

[0023] During the dynamic balancing test of the molecular pump, the unbalanced position and unbalanced mass are found by using an oscilloscope to test the weight. If the second end of the rotor assembly is unbalanced, a screwdriver can be inserted through the first through hole to add weight to the second threaded hole without disassembling the base. After the unbalanced position of the rotor assembly is determined, the shaft can be rotated so that the second threaded hole at the unbalanced position corresponds to the first through hole, thereby placing the weight screw in the second threaded hole and improving the dynamic balance of the rotor assembly. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the specific embodiments of this application or 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 application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the molecular pump in this application;

[0026] Figure 2 for Figure 1 Cross-sectional view along the AA direction;

[0027] Figure 3 This is a schematic diagram of the structure of the rotating shaft in this application.

[0028] [Explanation of Labels in the Attached Image]

[0029] 1: Shaft; 11: First end; 12: Second end; 121: First section; 122: Second section; 1221: First plane; 1222: Second plane; 123: First stepped surface; 2: Moving impeller; 21: Body; 22: Blade; 23: First counterweight area; 3: Positioning part; 30: Second counterweight area; 31: Spacer ring; 32: Fastener; 321: Nut; 322: Screw; 4: Housing; 41: Air inlet; 42: Exhaust port; 5: Carbon fiber traction cylinder; 6: Fixed traction cylinder; 7: Base; 71: Bottom wall; 72: Peripheral wall; 73: Accommodation space; 74: First through hole. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0032] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0035] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0036] In related technologies, the weighting position during online dynamic balancing is on the aluminum alloy traction cylinder. However, the aluminum alloy traction cylinder will expand and deform due to the high-speed rotation of the shaft assembly and the impeller. Therefore, a carbon fiber traction cylinder is used for airflow guidance. However, the carbon fiber traction cylinder structure cannot be used to set the weighting position. Therefore, it is necessary to develop a molecular pump structure that can meet the dynamic balancing test requirements of the molecular pump.

[0037] refer to Figure 1 and Figure 2 This application provides a rotor assembly for a molecular pump, including a shaft 1, a moving impeller 2, and a positioning part 3. Along the axial direction of the shaft 1, the shaft 1 has a first end 11 and a second end 12; the moving impeller 2 includes a body part 21 and blades 22 disposed on the body part 21, the body part 21 is connected to the first end 11, and the body part 21 is provided with a plurality of first counterweight areas 23, which are spaced apart circumferentially along the shaft 1; the positioning part 3 is disposed on the second end 12 to limit the rotation of the shaft 1, and the positioning part 3 is provided with a plurality of second counterweight areas 30, which are spaced apart circumferentially along the shaft 1.

[0038] The rotor assembly for a molecular pump proposed in this application embodiment has a positioning part 3 and a moving impeller 2 respectively disposed on opposite sides of a rotating shaft 1. The positioning part 3 is used to axially limit the rotating shaft 1 and prevent axial displacement. Multiple first counterweight areas 23 are provided on the main body of the moving impeller 2, and multiple second counterweight areas 30 are provided on the positioning part 3, achieving the purpose of setting counterweight points for dynamic balance testing on both sides of the rotor assembly. During dynamic balance testing, the unbalanced position and unbalanced mass are found by using an oscilloscope for trial weighting. By increasing the weight of the first counterweight areas 23 and / or the second counterweight areas 30, the rotor assembly gradually reaches a balanced state, thereby reducing vibration and wear caused by imbalance in the rotor assembly of the molecular pump during operation, and thus improving the safety of the molecular pump.

[0039] Optionally, the positioning part 3 includes a spacer ring 31 and a fastener 32. The spacer ring 31 is sleeved on the second end 12, and the fastener 32 engages with the end of the second end 12 along the axial direction of the rotating shaft 1 to press the spacer ring 31 against the second end 12. Multiple second counterweight areas 30 are disposed on the spacer ring 31 or the fastener 32. The spacer ring 31 is used to axially limit the rotating shaft 1, and the fastener 32 is used to press the spacer ring 31. The multiple second counterweight areas 30 disposed on the spacer ring 31 or the fastener 32 provide counterweight points on the second end 12 of the rotor assembly. By increasing the weight of the first counterweight area 23 and / or the second counterweight area 30, the dynamic balance of the molecular pump rotor assembly is adjusted, thereby improving the dynamic balance of the molecular pump rotor assembly.

[0040] Optionally, the fastener 32 includes a nut 321 and a screw 322 connected to each other. The screw 322 is threaded onto the end of the second end 12 along the axial direction of the shaft 1. The nut 321 abuts against the spacer ring 31. The second counterweight area 30 is disposed on the outer peripheral surface of the spacer ring 31 or the outer peripheral surface of the nut 321. The fastener 32 abuts against the spacer ring 31, positioning the spacer ring 31 at the second end 12 of the shaft 1 and preventing displacement on the shaft 1. The second counterweight area 30 is disposed on the outer peripheral surface of the spacer ring 31 or the outer peripheral surface of the nut 321, facilitating counterweighting of the rotor assembly during the dynamic balancing test of the molecular pump.

[0041] Optionally, refer to Figure 3 Along the axial direction of the rotating shaft 1, the second end 12 includes a first segment 121 and a second segment 122, with the second segment 122 being farther away from the first end 11 than the first segment 121. The outer peripheral surface of the second segment 122 includes a first plane 1221 and a second plane 1222 that are parallel to each other. The distance between the first plane 1221 and the second plane 1222 is less than the outer diameter of the first segment 121, so as to form a first stepped surface 123 on the second end 12. Along the axial direction of the rotating shaft 1, the spacer 31 abuts against the first stepped surface 123. The second segment 122 of the rotating shaft 1 has a first cut and a second cut extending along the axial direction of the rotating shaft 1, and the first cut and the second cut are symmetrically arranged. The first cut forms a first plane 1221 in the axial direction of the rotating shaft 1, and the first cut forms a first surface in the radial direction of the rotating shaft 1; the second cut forms a second plane 1222 in the axial direction of the rotating shaft 1, and the second cut forms a second surface in the radial direction of the rotating shaft 1. The first surface and the second surface together constitute the first stepped surface 123. The inner circumferential surface of the spacer ring 31 abuts against the first plane 1221 and the second plane 1222. The side of the spacer ring 31 facing the impeller 2 body 21 abuts against the first stepped surface 123, and the side of the spacer ring 31 away from the impeller 2 body 21 abuts against the fastener 32. When the shaft 1 rotates, the spacer ring 31 rotates synchronously with the shaft 1, and the abutment of the spacer ring 31 against the first stepped surface 123 of the shaft 1 restricts the axial displacement of the shaft 1. The abutment of the fastener 32 against the spacer ring 31 also restricts the axial displacement of the spacer ring 31.

[0042] Optionally, the first counterweight area 23 is constructed as a first threaded hole, and the second counterweight area 30 is constructed as a second threaded hole. The first threaded hole is machined on the outer peripheral surface of the body 21, and the second threaded hole is machined on the outer peripheral surface of the spacer 31 or the fastener 32. When performing dynamic balancing tests on the molecular pump, if the rotor assembly is unbalanced, the weight of the rotor assembly can be adjusted to a balanced state by adding counterweight screws through the first threaded hole and / or the second threaded hole.

[0043] This application also provides a molecular pump, including a housing 4 and the rotor assembly described in any of the above embodiments. The housing 4 has a receiving space, and the rotor assembly is disposed in the receiving space. In the dynamic balancing test of the molecular pump, the unbalanced position and unbalanced mass are found by using an oscilloscope to test the weight. By increasing the weight of the first counterweight area 23 and / or the second counterweight area 30, the rotor assembly is gradually brought to a balanced state, thereby reducing the vibration and wear of the rotor assembly of the molecular pump caused by imbalance during operation, and thus achieving the purpose of improving the safety of the molecular pump.

[0044] Optionally, refer to Figure 2 The housing 4 has an air inlet 41 and an exhaust port 42. The molecular pump also includes a carbon fiber traction cylinder 5, which is disposed inside the housing 4. The carbon fiber traction cylinder 5 is adapted to guide the airflow entering through the air inlet 41 to the exhaust port 42. The carbon fiber traction cylinder 5 acts as an airflow guide in the molecular pump and will not expand or deform due to the high-speed rotation of the rotor assembly. Furthermore, the carbon fiber traction cylinder 5 is lightweight, which can reduce the load on the rotor assembly.

[0045] In one alternative embodiment, the molecular pump includes a plurality of carbon fiber traction cylinders 5 and a plurality of fixed traction cylinders 6. The carbon fiber traction cylinders 5 are connected to the moving impeller 2 and extend axially toward the second end 12 along the shaft 1. The fixed traction cylinders 6 are connected to the housing 4 and extend axially toward the first end 11 along the shaft 1. The carbon fiber traction cylinders 5 and fixed traction cylinders 6 are alternately arranged, and there is a gap between the carbon fiber traction cylinders 5 and fixed traction cylinders 6 to form a Z-shaped airflow channel. After the impeller 22 of the molecular pump compresses the gas, it enters the airflow channel formed by the carbon fiber traction cylinders 5 and fixed traction cylinders 6, and is then discharged from the exhaust port 42.

[0046] Optionally, the molecular pump further includes a base 7, which includes a bottom wall 71 and a peripheral wall 72 surrounding the bottom wall 71. The bottom wall 71 and the peripheral wall 72 define an accommodating space 73. The bottom wall 71 corresponds to the axial end of the rotor assembly. The peripheral wall 72 is provided with a first through hole 74, which penetrates the peripheral wall 72 along its thickness direction. By providing the first through hole 74 on the base 7, the second counterweight area 30 can be counterweighted during the dynamic balancing test of the molecular pump, adjusting the rotor assembly to a balanced state without removing the base 7 and then adding weight to the second counterweight area 30.

[0047] Optionally, the second counterweight area 30 is constructed as a second threaded hole, and the axis of the first through hole 74 is on the same plane as the axis of the first threaded hole. The first through hole 74 communicates with the second threaded hole, and a screwdriver is passed through the first through hole 74 to place the counterweight screw in the second threaded hole, making the entire counterweight process of the dynamic balancing test convenient and quick.

[0048] Optionally, the diameter of the first through hole 74 is larger than the diameter of the second threaded hole; there are multiple first through holes 74, and the number of first through holes 74 is less than the number of second counterweight areas 30. During the dynamic balancing test of the molecular pump, the unbalanced position and unbalanced mass are found by using an oscilloscope to test the weight. If the second end 12 of the rotor assembly is unbalanced, the weight can be applied to the second threaded hole by passing a screwdriver through the first through hole 74, without disassembling the base 7. The larger diameter of the first through hole 74 facilitates the application of weight to the second threaded hole using a screwdriver. After the unbalanced position of the rotor assembly is determined, the shaft 1 can be rotated to align the second threaded hole at the unbalanced position with the first through hole 74, thereby placing the counterweight screw in the second threaded hole and improving the dynamic balance of the rotor assembly.

[0049] The molecular pump in this application uses a carbon fiber traction cylinder 5. Due to the limitations of the carbon fiber traction cylinder 5, a counterweight area cannot be set on it. Therefore, the spacer ring 31 on the rotating shaft 1 is thickened, and multiple second threaded holes are machined on the outer circumferential surface of the spacer ring 31. These multiple second threaded holes are spaced apart circumferentially along the spacer ring 31. A first through hole 74 is opened on the base 7 at a position corresponding to the second threaded hole. The first through hole 74 corresponds to and connects with the second threaded hole along its axial direction, so that there is space in the base 7 to insert a screwdriver and install the counterweight screw in the second threaded hole. In the dynamic balancing test of the molecular pump, if the imbalance position of the rotating shaft 1 assembly is at the second end 12, the screwdriver can be passed through the first through hole 74 and the counterweight screw can be placed in the second threaded hole, thus overcoming the difficulty of not being able to set a counterweight on the carbon fiber traction cylinder 5 in the molecular pump using the carbon fiber traction cylinder 5.

[0050] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0051] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0052] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0053] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A rotor assembly for a molecular pump, characterized in that, include: A rotating shaft, along the axial direction of the rotating shaft, the rotating shaft having a first end and a second end; The impeller includes a body and blades disposed on the body. The body is connected to the first end. The body is provided with a plurality of first counterweight areas, which are spaced apart circumferentially along the shaft. A positioning part is disposed at the second end to limit the rotation shaft. The positioning part is provided with a plurality of second counterweight areas, which are spaced apart circumferentially along the rotation shaft.

2. The rotor assembly according to claim 1, characterized in that, The positioning part includes a spacer and a fastener. The spacer is sleeved on the second end, and the fastener cooperates with the end of the second end along the axial direction of the rotating shaft to press the spacer tightly against the second end. The second counterweight area is disposed on the spacer ring or the fastener.

3. The rotor assembly according to claim 2, characterized in that, The fastener includes a nut and a screw connected to each other, the screw being threaded onto the end of the second end along the axial direction of the shaft, and the nut abutting against the spacer ring; The second counterweight area is located on the outer peripheral surface of the spacer ring or the outer peripheral surface of the nut.

4. The rotor assembly according to claim 2 or 3, characterized in that, Along the axial direction of the rotating shaft, the second end includes a first segment and a second segment, the second segment being farther away from the first end than the first segment; The outer peripheral surface of the second segment includes a first plane and a second plane that are parallel to each other. The distance between the first plane and the second plane is less than the outer diameter of the first segment, so as to form a first stepped surface on the second end. Along the axial direction of the rotating shaft, the spacer abuts against the first stepped surface.

5. The rotor assembly according to claim 1, characterized in that, The first counterweight area is constructed as a first threaded hole, and the second counterweight area is constructed as a second threaded hole.

6. A molecular pump, characterized in that, include: A housing having a receiving space; The rotor assembly according to any one of claims 1 to 5, wherein the rotor assembly is disposed in the receiving space.

7. The molecular pump according to claim 6, characterized in that, The housing has an air inlet and an exhaust outlet. The molecular pump also includes a carbon fiber traction cylinder disposed inside the housing. The carbon fiber traction cylinder is adapted to guide the airflow entering through the air inlet to the exhaust outlet.

8. The molecular pump according to claim 7, characterized in that, The molecular pump further includes a base, the base including a bottom wall and a peripheral wall surrounding the periphery of the bottom wall, the bottom wall and the peripheral wall defining the receiving space; The bottom wall corresponds to the axial end of the rotor assembly, and the peripheral wall is provided with a first through hole that penetrates the peripheral wall along the thickness direction.

9. The molecular pump according to claim 8, characterized in that, The second counterweight area is constructed as a second threaded hole, and the axis of the first through hole and the axis of the second threaded hole are on the same plane.

10. The molecular pump according to claim 9, characterized in that, The diameter of the first through hole is larger than the diameter of the second threaded hole; there are multiple first through holes, and the number of first through holes is less than the number of second counterweight areas.

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