Molecular pump

Abstract

The molecular pump comprises a shell set, a base with an air outlet and a shell which is arranged on the base in a buckled mode and provided with an air inlet. The turbine component is rotatably arranged between the base and the shell and comprises a blade part, an extension part coaxially connected with the blade part, a bent part connected with the intersection of the blade part and the extension part, and an annular space formed between the bent part and the extension part; the traction cylinder group comprises a first traction cylinder which is coaxially arranged on the base and partially enters the annular space of the turbine component; the winding channel sequentially comprises an air exhaust section communicated with the air inlet, a first compression section, a second compression section, a third compression section and a fourth compression section communicated with the air outlet. According to the molecular pump, the compression ratio and the air exhaust performance of the molecular pump can be improved under the condition that the size is hardly increased, so that the use requirement of the molecular pump in a high-end application scene is met.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of vacuum equipment. More specifically, the present invention relates to a molecular pump. Background Art

[0002] As a core component in modern vacuum technology, molecular pumps are widely used in the creation and maintenance of high vacuum environments, and they play an indispensable role in scientific research and industrial production. Their excellent performance, especially their high compression ratio and low reflux characteristics, are essential for maintaining and creating extreme vacuum environments.

[0003] The existing molecular pump mainly includes a shell group, a motor and a turbine component. The shell group includes a base with an air outlet and a shell buckled on the base and having an air inlet. The turbine component is rotatably arranged between the base and the shell, and has a blade portion fixed to the rotating shaft of the motor. During the operation of the molecular pump, the motor drives the blade group of the turbine component to rotate at a high speed in the shell, effectively cutting and compressing the gas molecules flowing into the molecular pump from the air inlet. These compressed gas molecules are guided to the air outlet in an orderly manner inside the molecular pump. In this process, the driving force of the turbine component and the guiding effect of the inner wall of the shell jointly ensure that the gas molecules can be discharged out of the pump efficiently and orderly.

[0004] However, in the fields of scientific research and industrial production, the requirements for vacuum environment are becoming increasingly stringent, and existing molecular pumps are difficult to fully meet the pursuit of extremely high vacuum in these fields. In addition, especially in application scenarios such as semiconductor manufacturing and laboratories, there are strict restrictions on the volume of molecular pumps. Therefore, it is urgent to improve the existing molecular pumps to meet the requirements of molecular pumps in high-end application scenarios. Summary of the invention

[0005] In order to solve one or more of the technical problems mentioned above, the present invention provides a molecular pump, the purpose of which is to solve how to improve its compression ratio and pumping performance without almost increasing its volume, so as to meet the use requirements of the molecular pump in high-end application scenarios.

[0006] According to the present invention, a molecular pump is provided, comprising: a shell group, a base having an air outlet and a shell body buckled on the base and having an air inlet; a turbine component rotatably arranged between the base and the shell body, and comprising a blade portion, an extension portion coaxially connected to the blade portion, a bent portion connected to the intersection of the blade portion and the extension portion, and an annulus formed between the bent portion and the extension portion; a traction cylinder group, comprising a first traction cylinder coaxially arranged on the base and partially entering into the annulus of the turbine component; a serpentine channel, which sequentially comprises an exhaust section connected to the air inlet and formed between the shell body and the blade portion of the turbine component, a suction section connected to the exhaust section and formed between the shell body and the bent portion of the turbine component a first compression section between the two parts, a second compression section connected to the first compression section and formed between the first traction tube and the bending part of the turbine component, a third compression section connected to the second compression section and formed between the first traction tube and the extension part of the turbine component, and a fourth compression section including a first part, the first part of which is formed between the extension part of the turbine component and the first traction tube, and is connected to the third compression section while being connected to the air outlet; wherein the first parts of the first compression section, the second compression section, the third compression section and the fourth compression section all accommodate a first spiral groove, a second spiral groove, a third spiral groove and a fourth spiral groove provided on the turbine component or the first traction tube.

[0007] Furthermore, the traction cylinder group also includes a second traction cylinder coaxially arranged on the base and located on the inner side of the extension portion of the turbine component, and the fourth compression section also includes a second portion formed between the extension portion of the turbine component and the second traction cylinder, the second portion of the fourth compression section is connected to the third compression section and connected to the air outlet, and the second portion of the fourth compression section also accommodates a fifth spiral groove provided on the second traction cylinder, and a connecting hole is provided on the extension portion of the turbine component to connect the third compression section with the second portion of the fourth compression section.

[0008] Further, the first spiral groove and the second spiral groove have the same direction, and are opposite to the third spiral groove, the fourth spiral groove and the fifth spiral groove.

[0009] Furthermore, the air extraction section is larger than the flow area of ​​any one of the first compression section, the second compression section, the third compression section and the fourth compression section.

[0010] Furthermore, the flow areas of the first compression section, the second compression section, and the third compression section decrease in sequence, and the flow area of ​​the fourth compression section is larger than the flow area of ​​the third compression section, but smaller than the flow area of ​​the first compression section.

[0011] Furthermore, an annular groove is provided on the inner bottom of the second traction cylinder.

[0012] Furthermore, the number of the first spiral grooves is 17, the helix angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area at the air inlet of the molecular pump is 1:4.7; the number of the second spiral grooves is 19, the helix angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area at the air inlet of the molecular pump is 1:5.5; the number of the third spiral grooves is 12, the helix angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area at the air inlet of the molecular pump is 1:6.4; the number of the fourth spiral grooves is 12, the helix angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area at the air inlet of the molecular pump is 1:6.4; the number of the fifth spiral grooves is 8, the helix angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area at the air inlet of the molecular pump is 1:7.9.

[0013] Furthermore, the molecular pump also includes a motor, which is fixed on the base of the shell group and located in the shell. The turbine component is integrally sleeved outside the motor and fixed to the rotating shaft of the motor through its blade portion.

[0014] Furthermore, the blade portion includes a multi-layer moving blade group spaced apart along the axial direction, and also includes a multi-layer fixed blade group spaced apart along the axial direction on the inner wall of the shell of the shell group, and the multi-layer moving blade group is alternately arranged in the multi-layer fixed blade group along the axial direction.

[0015] Furthermore, the molecular pump is a magnetically suspended molecular pump.

[0016] A molecular pump of the present invention realizes the initial stage of the molecular pumping function by rotating the turbine component, especially the blade part thereof, in the housing. The drawn gas is then compressed through the first compression section, the second compression section, the third compression section and the fourth compression section and discharged through the air outlet provided on the base. A serpentine passage mainly composed of the air pumping section, the first compression section, the second compression section, the third compression section and the fourth compression section and connecting the air inlet and the air outlet is formed between the housing, the turbine component and the traction cylinder group, and repeatedly bends between the three to make full use of the space in the molecular pump. This not only improves the flow path of the gas molecules in the molecular pump, but also can increase the compression ratio of the molecular pump by adding at least one compression section, thereby improving the air pumping performance of the molecular pump. At the same time, by constructing a more tortuous serpentine passage inside the molecular pump, the backflow phenomenon of the gas molecules during the transmission process can also be effectively reduced, further improving the compression ratio of the molecular pump and its air pumping performance. In other words, the improvement of the molecular pump is mainly to improve its compression ratio and pumping performance by increasing the compactness without increasing the volume, which can effectively meet the use requirements of the molecular pump in high-end application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0018] Figure 1 A three-dimensional diagram of a molecular pump according to an embodiment of the present invention is shown;

[0019] Figure 2 A cross-sectional view of a molecular pump according to an embodiment of the present invention is shown;

[0020] Figure 3 Shows Figure 1 A partial enlarged view of the middle area A;

[0021] Figure 4 Shows Figure 2 A three-dimensional view showing the assembly state of the bent portion of the turbine component and the first traction cylinder;

[0022] Figure 5 Shows Figure 2 A perspective view of the first traction cylinder shown;

[0023] Figure 6 Shows Figure 2 A perspective view of the assembly state of the extension portion of the turbine component and the second traction cylinder is shown.

[0024] Explanation of the reference numerals: 100, molecular pump; 1001, assembly area; 1002, rotating shaft; 1, shell group; 11, base; 111, air outlet; 12, shell; 121, air inlet; 2, turbine component; 21, blade part; 211, moving blade group; 212, fixed blade group; 22, extension part; 221, connecting hole; 23, bending part; 24, annulus; 3, traction cylinder group; 31, first traction cylinder; 32, second traction cylinder; 4, winding channel; 41, exhaust section; 42, first compression section; 421, first spiral groove; 43, second compression section; 431, second spiral groove; 44, third compression section; 441, third spiral groove; 45, fourth compression section; 451, first part; 452, fourth spiral groove; 453, second part; 454, fifth spiral groove. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0026] The embodiment of the present invention provides a molecular pump 100, see Figure 1 and Figure 2 . Among them, the molecular pump 100, as a core component in modern vacuum technology, is widely used in the creation and maintenance of a high vacuum environment, and plays an indispensable role in scientific research and industrial production. Among them, the turbomolecular pump 100 has been widely used due to its high pumping speed, no oil pollution, and simple maintenance. The molecular pump 100 in the present application is preferably a magnetic levitation molecular pump 100, which has a longer bearing life and the rotor can more easily reach a higher speed, which is conducive to improving the compression ratio for gas molecules. Among them, the compression ratio is an important indicator to measure the performance of the molecular pump 100, which represents the ability of the molecular pump 100 to transport gas from a low-pressure area to a high-pressure area. A high compression ratio means that the molecular pump 100 can handle a large amount of gas load more effectively, and at the same time has better performance in maintaining a high vacuum.

[0027] In this embodiment, the molecular pump 100 includes a shell assembly 1 and a motor disposed in the shell assembly 1, for example, the shell assembly 1 has an assembly area 1001 for mounting the motor. The shell assembly 1 specifically includes a base 11 having an air outlet 111 and a shell 12 buckled on the base 11 and having an air inlet 121, and the motor is fixedly disposed on the base 11 of the shell assembly 1 and is located in the shell 12. The molecular pump 100 also includes a turbine component 2 disposed in the shell assembly 1, and the turbine component 2 is fixedly sleeved outside the motor so that the motor can drive the turbine component 2 to rotate in the shell assembly 1 and generate suction.

[0028] The turbine component 2 includes a blade portion 21, and the turbine component 2 can be fixed to the rotating shaft 1002 of the motor through its blade portion 21. The blade portion 21 includes a plurality of moving blade groups 211 spaced apart in the axial direction, and the plurality of moving blade groups 211 are alternately arranged in the axial direction in a plurality of fixed blade groups 212. Compared with the existing turbine components, the turbine component 2, in addition to the blade portion 21, also includes an extension portion 22 coaxially connected to the blade portion 21, a bending portion 23 provided at the intersection of the extension portion 22 and the blade portion 21, and an annulus 24 formed between the bending portion 23 and the extension portion 22.

[0029] In order to improve the compression ratio of the molecular pump 100, the molecular pump 100 further includes a traction cylinder group 3 and a serpentine channel 4 for connecting the air inlet 121 and the air outlet 111. As an example, refer to Figure 2 and Figure 3 The traction cylinder group 3 at least includes a first traction cylinder 31 coaxially arranged on the base 11 and partially entering the annulus 24 of the turbine component 2. The serpentine passage 4 sequentially includes an air extraction section 41 connected to the air inlet 121 and formed between the shell 12 and the blade portion 21 of the turbine component 2, a first compression section 42 connected to the air extraction section 41 and formed between the shell 12 and the bending portion 23 of the turbine component 2, a second compression section 43 connected to the first compression section 42 and formed between the first traction cylinder 31 and the bending portion 23 of the turbine component 2, a third compression section 44 connected to the second compression section 43 and formed between the first traction cylinder 31 and the extension portion 22 of the turbine component 2, and a first portion 451 (refer to Figure 5 ) of the fourth compression section 45. It should be noted that the first portion 451 of the fourth compression section 45 is formed between the extension portion 22 of the turbine component 2 and the first traction cylinder 31, and is connected to the third compression section 44 while being connected to the air outlet 111. The first compression section 42 accommodates the first spiral groove 421 provided on the turbine component 2, the second compression section 43 accommodates the second spiral groove 431 provided on the first traction cylinder 31, the third compression section 44 accommodates the third spiral groove 441 provided on the first traction cylinder 31, and the first portion 451 of the fourth compression section 45 accommodates the fourth spiral groove 452 provided on the first traction cylinder 31.

[0030] Based on the above description, the initial stage of the molecular pump 100 is realized by the rotation of the rotating turbine component 2, especially the rotation of its blade portion 21 in the housing 12, and the drawn gas is then compressed through the first compression section 42, the second compression section 43, the third compression section 44 and the fourth compression section 45 and discharged through the outlet 111 provided on the base 11. The serpentine channel 4, which is mainly composed of the pumping section 41, the first compression section 42, the second compression section 43, the third compression section 44 and the fourth compression section 45 and connects the air inlet 121 and the air outlet 111, is formed between the housing 12, the turbine component 2 and the traction cylinder group 3, and repeatedly bends between the three to make full use of the space in the molecular pump 100, which not only improves the flow path of the gas molecules in the molecular pump 100, but also can improve the compression ratio of the molecular pump 100 by adding at least one compression section, thereby improving the pumping performance of the molecular pump 100. At the same time, by constructing a more tortuous winding channel 4 inside the molecular pump 100, the backflow phenomenon of gas molecules during the transmission process can also be effectively reduced, and the compression ratio and the air pumping performance of the molecular pump 100 can be further improved. In other words, the improvement of the molecular pump 100 is mainly to improve its compression ratio and air pumping performance by increasing the compactness without increasing the volume, which can effectively meet the use requirements of the molecular pump 100 in high-end application scenarios.

[0031] In this embodiment, if Figure 2 , Figure 5 and Figure 6 As shown, the traction cylinder group 3 at least includes a second traction cylinder 32 coaxially arranged on the base 11 and located inside the extension portion 22 of the turbine component 2, and the fourth compression section 45 at least includes a second portion 453 formed between the extension portion 22 of the turbine component 2 and the second traction cylinder 32 (refer to Figure 6 ), the second portion 453 of the fourth compression section 45 is connected to the third compression section 44 and connected to the air outlet 111, and the second portion 453 of the fourth compression section 45 also accommodates a fifth spiral groove 454 provided on the second traction cylinder 32, and a connecting hole 221 is provided on the extension portion 22 of the turbine component 2 to connect the third compression section 44 with the second portion 453 of the fourth compression section 45.

[0032] The second part 453 added to the fourth compression section 45 realizes the effective diversion of the gas molecules in the third compression section 44. Through this diversion, the gas molecules that originally flowed directly to the first part 451 of the fourth compression section 45 can now be partially received by the second part 453, thereby promoting the smooth transition of the gas molecules from the third compression section 44 to the fourth compression section 45. This design cleverly reduces the backflow phenomenon when the gas molecules are transferred from the third compression section 44 to the fourth compression section 45, effectively reduces the possibility of backflow of gas molecules, and thus significantly improves the compression ratio of the molecular pump 100. At the same time, the first part 451 and the second part 453 of the fourth compression section 45 are directly connected to the gas outlet 111. This layout not only optimizes the discharge path of the gas molecules in the winding channel 4, but also further improves the compression efficiency of the molecular pump 100. In general, the addition of the second part 453 of the fourth compression section 45 comprehensively improves the compression performance of the molecular pump 100 on gas molecules by diverting, reducing backflow and optimizing the discharge of gas molecules.

[0033] As an example, the first spiral groove 421 and the second spiral groove 431 have the same direction, and are opposite to the third spiral groove 441, the fourth spiral groove 452 and the fifth spiral groove 454. Under the premise of ensuring that the molecular pump 100 realizes the basic functions, in order to realize the setting of the opening direction of the above spiral grooves, the opening positions of the spiral grooves at different compression parts should also be different, specifically: the first spiral groove 421 should be opened on the outer wall of the bending part 23, the second spiral groove 431, the third spiral groove 441 and the first part 451 of the fourth spiral groove 452 should be opened on the side wall of the first traction cylinder 31, and the second part 453 of the fourth spiral groove 452 should be opened on the outer wall of the second traction cylinder 32. Through the setting of the above-mentioned spiral groove rotation direction, most of the spiral grooves in the serpentine channel 4 are opened on the first traction cylinder 31 and the second traction cylinder 32. Compared with opening annular grooves on the side wall of the annulus 24 of the turbine component 2, the processing difficulty of opening spiral grooves on the first traction cylinder 31 and the second traction cylinder 32 is less. As an implementation method, the first spiral groove 421 can also be set in a direction different from the above-mentioned opening direction, and the spiral groove can be opened on the inner wall of the shell 12. Through this implementation method, all the spiral grooves are opened on the traction cylinder group 3 and the shell group 1, which is beneficial to improve the rigidity of the turbine component 2 while maintaining a high degree of integration, and is beneficial to improve the stability of the molecular pump 100 during operation, improve the life of the molecular pump 100, and reduce the probability of molecular damage.

[0034] As an example, in order to ensure that the molecular pump 100 has sufficient pumping capacity, the flow area of ​​the pumping section 41 should be greater than the flow area of ​​any one of the first compression section 42, the second compression section 43, the third compression section 44 and the fourth compression section 45. Preferably, in order to further optimize the channel structure, an annular groove is provided at the inner bottom of the second traction cylinder 32, and the flow areas of the first compression section 42, the second compression section 43 and the third compression section 44 are reduced in sequence, and the flow area of ​​the fourth compression section 45 is greater than the flow area of ​​the third compression section 44, but smaller than the flow area of ​​the first compression section 42. By controlling the flow areas of the first compression section 42, the second compression section 43 and the third compression section 44 to decrease in sequence, the molecular pump 100 can further compress the gas molecules when transporting the gas molecules, and by controlling the flow area of ​​the fourth compression section to be greater than the flow area of ​​the third compression section 44, it is convenient for the gas molecules to be discharged from the molecular pump 100 after being compressed.

[0035] Preferably, in order to ensure the compression capacity of the fourth compression section 45 for gas molecules, the flow area of ​​the fourth compression section 45 should also meet the following settings at the same time: the flow area of ​​any one of the first part 451 and the second part 453 of the fourth compression section 45 is not greater than the flow area of ​​the third compression section 44.

[0036] In this embodiment, the number of the first spiral grooves 421 is 17, the spiral angle is 32°, and the ratio of their total cross-sectional area (the sum of the flow areas at any position) to the cross-sectional area of ​​the molecular pump 100 at the air inlet 121 is 1:4.7. The number of the second spiral grooves 431 is 19, the spiral angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area of ​​the molecular pump 100 at the air inlet 121 is 1:5.5. The number of the third spiral grooves 431 is 12, the spiral angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area of ​​the molecular pump 100 at the air inlet 121 is 1:6.4. The number of the fourth spiral grooves 431 is 12, the spiral angle is 32°, and the ratio of their total cross-sectional area to the cross-sectional area of ​​the molecular pump 100 at the air inlet 121 is 1:6.4. The number of the fifth spiral grooves 431 is 8, the spiral angle is 32°, and the ratio of the total cross-sectional area thereof to the cross-sectional area of ​​the molecular pump 100 at the air inlet is 1:7.9. Through a large number of experiments, it is known that when the first spiral groove 421, the second spiral groove 431, the third spiral groove 441, the fourth spiral groove 452 and the fifth spiral groove 454 meet the above conditions, the compression ratio and the effect of suppressing backflow of the molecular pump 100 during operation can be maximized.

[0037] In summary, the molecular pump mentioned above is easier to process and can improve its compression ratio and pumping performance without increasing its volume, thereby meeting the use requirements of the molecular pump in high-end application scenarios.

[0038] In the above description of the present application, unless otherwise clearly specified and limited, the terms "fixed", "installed", "connected" or "connected" and the like should be understood in a broad sense. For example, with regard to the term "connection", it can be a fixed connection, a detachable connection, or an integral one; 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 the internal connection of two elements or the interaction relationship between two elements. Therefore, unless otherwise clearly defined in the present application, those skilled in the art can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0039] According to the above description of the present application, those skilled in the art may also understand that the terms used below, such as "inner", "outer", "axial", "radial", "circumferential", etc., which indicate orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings of the present application, and are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or element involved must have the specific orientation, be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0040] In addition, the terms "first" or "second" used in this application to refer to numbers or ordinals are only used for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0041] Although multiple embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art may conceive of many changes, modifications, and alternatives without departing from the thought and spirit of the present invention. It should be understood that in the process of practicing the present invention, various alternatives to the embodiments of the present invention described herein may be adopted. The appended claims are intended to define the scope of protection of the present invention, and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A molecular pump, characterized in that: include: A shell assembly, a base with an air outlet and a shell body buckled on the base and having an air inlet; a turbine component rotatably disposed between the base and the housing, and comprising a blade portion, an extension portion coaxially connected to the blade portion, a bent portion connected to an intersection of the blade portion and the extension portion, and an annulus formed between the bent portion and the extension portion; A traction cylinder assembly, comprising a first traction cylinder coaxially disposed on the base and partially entering the annulus of the turbine component; a serpentine passage, which sequentially includes an air extraction section connected to the air inlet and formed between the housing and the blade portion of the turbine component, a first compression section connected to the air extraction section and formed between the housing and the bent portion of the turbine component, a second compression section connected to the first compression section and formed between the first traction cylinder and the bent portion of the turbine component, a third compression section connected to the second compression section and formed between the first traction cylinder and the extended portion of the turbine component, and a fourth compression section including a first portion, the first portion of the fourth compression section being formed between the extended portion of the turbine component and the first traction cylinder, and connected to the third compression section while being connected to the air outlet; Among them, the first parts of the first compression section, the second compression section, the third compression section and the fourth compression section all accommodate the first spiral groove, the second spiral groove, the third spiral groove and the fourth spiral groove provided on the turbine component or the first traction cylinder.

2. The molecular pump according to claim 1, characterized in that: The traction cylinder group also includes a second traction cylinder coaxially arranged on the base and located on the inner side of the extension portion of the turbine component. The fourth compression section also includes a second portion formed between the extension portion of the turbine component and the second traction cylinder. The second portion of the fourth compression section is connected to the third compression section and connected to the air outlet. The second portion of the fourth compression section also accommodates a fifth spiral groove provided on the second traction cylinder. A connecting hole that connects the third compression section with the second portion of the fourth compression section is provided on the extension portion of the turbine component.

3. The molecular pump according to claim 2, characterized in that: The first spiral groove and the second spiral groove have the same direction and are opposite to the third spiral groove, the fourth spiral groove and the fifth spiral groove.

4. The molecular pump according to claim 2, characterized in that: The air extraction section is larger than the flow area of ​​any one of the first compression section, the second compression section, the third compression section and the fourth compression section.

5. The molecular pump according to claim 2, characterized in that: The flow areas of the first compression section, the second compression section, and the third compression section decrease in sequence, and the flow area of ​​the fourth compression section is larger than the flow area of ​​the third compression section, but smaller than the flow area of ​​the first compression section.

6. The molecular pump according to claim 2, characterized in that: An annular groove is provided on the inner bottom of the second traction cylinder.

7. The molecular pump according to claim 2, characterized in that: The number of the first spiral grooves is 17, the spiral angle is 32°, and the ratio of the total cross-sectional area thereof to the cross-sectional area at the air inlet of the molecular pump is 1:4.7; The number of the second spiral grooves is 19, the spiral angle is 32°, and the ratio of the total cross-sectional area thereof to the cross-sectional area at the inlet of the molecular pump is 1:5.5; The number of the third spiral grooves is 12, the spiral angle is 32°, and the ratio of the total cross-sectional area thereof to the cross-sectional area at the air inlet of the molecular pump is 1:6.4; The number of the fourth spiral grooves is 12, the spiral angle is 32°, and the ratio of the total cross-sectional area thereof to the cross-sectional area at the air inlet of the molecular pump is 1:6.4; The number of the fifth spiral grooves is 8, the spiral angle is 32°, and the ratio of the total cross-sectional area thereof to the cross-sectional area at the air inlet of the molecular pump is 1:7.

9.

8. The molecular pump according to claim 2, characterized in that: The molecular pump further comprises a motor, which is fixed on the base of the shell group and located in the shell. The turbine component is entirely sleeved outside the motor and is fixed on the rotating shaft of the motor through its blade portion.

9. The molecular pump according to claim 2, characterized in that: The blade portion includes a plurality of moving blade groups spaced apart along the axial direction, and also includes a plurality of fixed blade groups spaced apart along the axial direction provided on the inner wall of the shell of the shell group, wherein the plurality of moving blade groups are alternately arranged in the plurality of fixed blade groups along the axial direction.

10. The molecular pump according to claim 1, characterized in that: The molecular pump is a magnetically suspended molecular pump.

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