CN116877435A

CN116877435A - Vacuum pump

Info

Publication number: CN116877435A
Application number: CN202311091764.1A
Authority: CN
Inventors: 魏民; 常悦; 叶乐志; 张建平
Original assignee: Beijing Tongjia Hongrui Technology Co ltd; Beijing University of Technology
Current assignee: Beijing Tongjia Hongrui Technology Co ltd; Beijing University of Technology
Priority date: 2023-08-28
Filing date: 2023-08-28
Publication date: 2023-10-13

Abstract

The application provides a vacuum pump, which comprises a pump body and a coupler, wherein the pump body comprises a pump shell and an input shaft rotatably arranged on the pump shell; the shaft coupling comprises an outer rotor, a magnetic conduction sleeve and an inner rotor which are coaxially arranged, wherein the inner rotor is fixed on the peripheral side of an input shaft and is coaxially arranged with the input shaft, the magnetic conduction sleeve comprises a magnetic conduction part and a mounting part, the magnetic conduction part is sleeved on the periphery of the inner rotor, the mounting part is annularly arranged on the peripheral side of the magnetic conduction part and extends along the radial direction of the magnetic conduction part, the mounting part is fixed on a pump shell, and the outer rotor is arranged on the peripheral direction of the magnetic conduction sleeve and is used for being connected with a motor. In the vacuum pump provided by the application, the mounting part is fixed on the pump shell, the magnetic conduction sleeve is sealed with the pump body, the input shaft and the inner rotor are sealed in the magnetic conduction sleeve, the structure is simple, and the sealing reliability is high.

Description

Vacuum pump

Technical Field

The application belongs to the technical field of vacuum pumps, and particularly relates to a vacuum pump.

Background

In order to obtain a high vacuum environment of 0.1Pa and above, the vacuum pump needs a motor to drive a rotor to rotate for tens of thousands of revolutions per minute and pump air, and in order to maintain the vacuum in a pump cavity, various sealing structures are needed to be arranged at the connection positions of the pump and each part. The traditional sealing structure is complex and is easy to wear.

Disclosure of Invention

The embodiment of the application provides a vacuum pump, which makes up the defects of the prior art.

In a first aspect, an embodiment of the present application provides a vacuum pump, including: the pump body comprises a pump shell and an input shaft rotatably arranged on the pump shell;

the shaft coupling comprises an outer rotor, a magnetic conduction sleeve and an inner rotor, wherein the outer rotor, the magnetic conduction sleeve and the inner rotor are coaxially arranged, the inner rotor is fixed on the periphery of the input shaft and is coaxially arranged with the input shaft, the magnetic conduction sleeve comprises a magnetic conduction part and a mounting part, the magnetic conduction part is sleeved on the periphery of the inner rotor, the mounting part is annularly arranged on the periphery of the magnetic conduction part and radially extends along the magnetic conduction part, the mounting part is fixed on the pump shell, and the outer rotor is arranged on the periphery of the magnetic conduction sleeve and is used for being connected with a motor.

In one embodiment, a flange portion is fixed to a side of the mounting portion facing the pump case, and a projection fitted to the flange portion is fixed to the pump case, and the flange portion abuts against a side portion of the projection.

In one embodiment, the outer rotor comprises a first permanent magnet group and a first induction transmission group which are arranged at intervals, and the inner rotor comprises a second permanent magnet group which is arranged opposite to the first permanent magnet group in the radial direction and a second induction transmission group which is arranged corresponding to the first induction transmission group in the radial direction.

In one embodiment, the first inductive drive set includes a plurality of first inductive drives configured as permanent magnets; the second inductive drive assembly includes a second inductive drive, the second inductive drive configured as a conductor.

In one embodiment, the second inductive transmission member is configured as a conductor block, and a plurality of conductor blocks are arranged, and the second inductive transmission member is in one-to-one fit with the first inductive transmission member.

In one embodiment, the inner rotor further comprises an inner rotor core, the second induction transmission set is arranged on the periphery of the inner rotor core, and a through hole is axially formed in the inner rotor core for the input shaft to penetrate.

In one embodiment, the magnetizing direction of the first inductive transmission member is radial, and the polarities of the adjacent magnetic poles of the first inductive transmission member are opposite.

In one embodiment, the outer rotor further comprises a first magnetic steel fixing sleeve and a second magnetic steel fixing sleeve which are connected, wherein the first magnetic steel fixing sleeve is positioned at the periphery of the first permanent magnet group, and the second magnetic steel fixing sleeve is positioned at the periphery of the first induction transmission group.

In an embodiment, the outer rotor further comprises a fixed connecting sleeve, the fixed connecting sleeve comprises a first connecting portion and a second connecting portion, the first connecting portion is located between the first permanent magnet group and the first induction transmission group and extends along a direction deviating from the inner rotor, the second connecting portion is fixed at one end, away from the first permanent magnet group, of the first connecting portion, and two ends, along the axial direction, of the second connecting portion are respectively abutted to the first magnetic steel fixed sleeve and the second magnetic steel fixed sleeve.

In one embodiment, the relative permeability of the fixed connection sleeve is 10-200.

In the vacuum pump provided by the embodiment of the application, the pump body comprises the pump shell and the input shaft rotatably arranged on the pump shell, and the input shaft can rotate so as to manufacture a vacuum environment; the coupler comprises an outer rotor, a magnetic conduction sleeve and an inner rotor which are coaxially arranged, and the inner rotor is connected with the outer rotor through a magnetic circuit. The inner rotor is fixed in input shaft week side to set up with the input shaft is coaxial, and the magnetic conduction cover includes magnetic conduction portion and installation department, and magnetic conduction portion cover is located the inner rotor periphery, and the installation department is located magnetic conduction portion periphery side in the ring to extend along magnetic conduction portion's radial, installation department is fixed in the pump case, the outer rotor is in magnetic conduction cover's circumference is upwards set up for connect the motor. When the motor works, the rotating motor output shaft drives the outer rotor to rotate, the outer rotor can drive the inner rotor to rotate through the magnetic conduction sleeve, and the inner rotor further drives the input shaft to rotate, so that a vacuum environment is manufactured. And the installation department is fixed in the pump case, seals between magnetic conduction cover and the pump body, and input shaft and inner rotor seal in magnetic conduction cover, simple structure, seal reliability is high.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is evident that the figures in the following description are only some embodiments of the application, from which other figures can be obtained without inventive effort for a person skilled in the art.

For a more complete understanding of the present application and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings. Wherein like reference numerals refer to like parts throughout the following description.

Fig. 1 is a schematic structural diagram of a vacuum pump according to an embodiment of the present application;

FIG. 2 is an enlarged view of a portion of FIG. 1 at A;

FIG. 3 is a schematic view of a portion of the coupling of FIG. 1;

fig. 4 is a schematic view of a part of the inner rotor in fig. 1.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.

As shown in fig. 1, the vacuum pump provided by the embodiment of the application comprises a pump body 10 and a coupling 30, wherein the pump body 10 comprises a pump shell 11 and an input shaft 13 rotatably mounted on the pump shell 11. The input shaft 13 of the pump body 10 is connected with the output shaft of the motor through a coupling 30 to realize synchronous movement of the output shaft of the motor and the input shaft 13 of the pump body 10.

Since the input shaft 13 of the pump body is required to extend out of the pump housing 11, a seal is required between the input shaft and the pump housing to ensure a high vacuum in the pump body. The traditional sealing mode is to set up dynamic seal structure to the input shaft of the pump body and pump case. However, the dynamic seal structure is complex, the installation difficulty is high, the requirement on the manufacturing process is high, if the installation is not in place, or the vacuum leakage is easy to be caused due to the manufacturing error generated by the manufacturing process, so that the maintenance and repair cost of the vacuum pump is increased, in addition, the abrasion of the dynamic seal structure is aggravated at high rotating speed, and the leakage of the vacuum pump is easy to be caused.

To solve the above problem, as shown in fig. 2, the coupling 30 in the embodiment of the present application may include an outer rotor 31, a magnetically conductive sleeve 33, and an inner rotor 35 coaxially disposed, wherein the inner rotor 35 is fixed on a circumferential side of the input shaft 13 and coaxially disposed with the input shaft 13, and as shown in fig. 3, the magnetically conductive sleeve 33 includes a magnetically conductive portion 331 and a mounting portion 333, the magnetically conductive portion 331 is sleeved on an outer circumference of the inner rotor 35, the mounting portion 333 is annularly disposed on an outer circumference side of the magnetically conductive portion 331 and extends in a radial direction of the magnetically conductive portion 331, the mounting portion 333 is connected with the pump housing 11, and the outer rotor 31 is disposed in a circumferential direction of the magnetically conductive sleeve 33 for connecting to a motor. The installation department is fixed in the pump case to seal input shaft and inner rotor in the magnetic conduction cover, so, seal the magnetic conduction cover with the pump body between, simple structure, the leakproofness is good.

In the embodiment of the present application, the magnetic conductive portion 331 of the magnetic conductive sleeve 33 is sleeved on the outer periphery of the inner rotor 35, the mounting portion 333 of the magnetic conductive sleeve 33 is annularly disposed on the outer periphery of the magnetic conductive portion 331 and extends along the radial direction of the magnetic conductive portion 331, the mounting portion 333 is fixed to the pump housing 11, and the outer rotor 31 is disposed in the circumferential direction of the magnetic conductive sleeve 33 for connecting to a motor. Wherein the magnetic sleeve is made of magnetic conductive material, for example: electromagnetic pure iron, iron-silicon alloy, and the like. The attachment 333 and the pump casing 11 may be screw-coupled, snap-coupled, welded, or the like. For example, the mounting portion 333 may be provided with bolt holes, so that bolts can be used to fix the magnetic sleeve to the pump casing. In addition, the coupling in the embodiment of the application adopts a transmission mode of a magnetic coupling, so that physical contact between the input shaft of the pump body and the motor can be avoided.

As shown in fig. 2, in the embodiment of the present application, one end of the magnetic conduction portion 331 of the magnetic conduction sleeve 33 facing away from the mounting portion 333 may be blocked, and the end of the mounting portion 333 of the magnetic conduction sleeve 33 has an opening 330 communicating with the outside, so that, after the mounting portion 333 is fixed to the pump housing 11, a sealed chamber is formed between the magnetic conduction sleeve 33 and the pump body 10, and the input shaft is sealed in the sealed chamber. Simple structure, the reliability is high to improve the sealed effect of the input shaft of the pump body.

As shown in fig. 2 and 3, in order to improve the sealing effect, in one embodiment, the mounting portion 333 may be fixed with a flange portion 335 on a side facing the pump housing 11, the pump housing 11 is fixed with a projection 15 that mates with the flange portion 335, and the flange portion 335 abuts against a side portion of the projection 15.

In the embodiment of the present application, the flange portion 335 is matched with the bump 15, so as to facilitate fixing and installing the magnetic conductive sleeve 33, during installation, the flange portion 335 is abutted against the side portion of the bump 15, and then the installation portion 333 is connected and fixed with the bump 15 by using a connecting piece such as a bolt, a screw, a steel nail, etc., so that the magnetic conductive sleeve 33 and the pump shell 11 are relatively fixed, and no relative movement is easy to occur. The mounting portion 333 of the magnetic sleeve 33 may be directly fixed to the pump casing 11, or may be fixed to the protrusion 15, and the fixing manner may be a screw connection manner, a clamping manner, a welding manner, or the like. The boss 15 and the pump housing 11 may be of an integrally formed construction.

Further, in order to improve the sealing effect, when the mounting portion 333 is fixed to the protrusion 15, a sealing ring is further provided between the mounting portion 333 and the protrusion 15.

Specifically, a sealing ring may be disposed on a side of the mounting portion 333 facing the bump 15, the sealing ring may be disposed beside the flange portion 335, and a sealing groove may be disposed at a position on the bump 15 corresponding to the sealing ring, so, when the flange portion 335 is matched with the bump 15, the sealing ring is correspondingly disposed in the sealing groove when the mounting portion 333 is fixed to the bump 15. In another embodiment, the seal ring may be a seal groove formed directly on the bump and protruding from the seal groove, so that the mounting portion 333 and the bump 15 are sealed when the mounting portion 333 is fixed to the bump 15. Therefore, the internal environment of the vacuum pump is isolated from the outside through the magnetic conduction sleeve, and the air extraction reliability is improved.

As shown in fig. 1, 2 and 3, in the embodiment of the present application, the vacuum pump mainly includes a motor, a coupling, and a pump body, where the motor 40 is fixed on the pump housing 11, an output shaft 403 of the motor 40 is connected to an outer rotor of the coupling, specifically, a pair of input shafts are disposed in the pump body 10, and gears are disposed at two ends of the input shafts, specifically, a first input shaft and a second input shaft, which may rotate through deep groove ball bearings as supports, and the first input shaft and the second input shaft may be meshed through the gears 1311 for transmission.

The first input shaft is connected with an inner rotor of the coupler, specifically, the inner rotor of the coupler can be fixed on the first input shaft through a key slot and a radial jackscrew hole, and an outer rotor of the coupler can be fixed on an output shaft of the motor through the key slot and the radial jackscrew hole. In the embodiment of the application, a magnetic conduction sleeve 33 is arranged between an inner rotor 35 and an outer rotor 31 of the coupler 30, and the magnetic conduction sleeve 33 is fixed on the pump shell 11, so that an input shaft is sealed in the pump shell 11, and a sealing ring is arranged at the joint of the magnetic conduction sleeve and the pump shell 11. When the motor 40 works, the first input shaft is rotated under the magnetic force of the inner rotor 35 and the outer rotor 31 of the coupler 30, and the first input shaft drives the driven second input shaft through the meshing gear, so that the periodic air suction and exhaust of the vacuum pump are realized.

The inner rotor and the outer rotor of the traditional permanent magnet coupling are usually driven by permanent magnets, and when the rotation speed difference occurs between the outer rotor and the inner rotor, the driving failure is easy to be caused.

To solve the above-mentioned problems, in the embodiment of the present application, as shown in fig. 3, the outer rotor 31 includes a first permanent magnet group 311 and a first induction transmission group 313 that are disposed at intervals, and the inner rotor 35 includes a second permanent magnet group 351 disposed opposite to the first permanent magnet group 311 in the radial direction, and a second induction transmission group 353 disposed corresponding to the first induction transmission group 313 in the radial direction.

In the embodiment of the present application, the outer rotor 31 includes a first permanent magnet group 311 and a first induction transmission group 313 that are disposed at intervals, the inner rotor 35 includes a second permanent magnet group 351 that is disposed opposite to the first permanent magnet group 311 in a radial direction, and a second induction transmission group 353 that is disposed corresponding to the first induction transmission group 313 in a radial direction, and the first permanent magnet group 311 and the second permanent magnet group 351 cooperate to generate magnetic transmission, and the first induction transmission group 313 and the second induction transmission group 353 cooperate to generate eddy current transmission.

As will be readily appreciated, eddy current drives are driven by the interaction of the eddy current magnetic field generated in the conductor cutting induction line with the source magnetic field, the strength of the eddy current being proportional to the relative speed of movement. In this way, when the coupling is under the over-torque condition, the inner rotor and the outer rotor of the coupling 30 will generate relative motion, and at this time, the first inductive transmission set 313 and the second inductive transmission set 353 cooperate to generate an inductive current, so as to generate torque compensation. So that the inner rotor and the outer rotor of the coupling 30 can rotate more quickly and synchronously. When the inner rotor and the outer rotor of the coupler synchronously rotate, the moment generated by no relative motion between the two rotors is compensated to be zero. At this time, the first permanent magnet group 311 and the second permanent magnet group 351 cooperate to perform magnetic transmission.

In the embodiment of the application, two different magnetic circuits are integrated on the inner rotor and the outer rotor, so that the decoupling transmission of vortex and permanent magnet is realized, the moment capacity of a coupler in a vacuum pump and the starting capacity of a pump body are improved, the transmission under complex working conditions can be realized, and the transmission failure is not easy to be caused when the rotation speed of the outer rotor and the inner rotor is different.

In one embodiment, the first inductive drive set 313 may include a plurality of first inductive drives configured as permanent magnets; the second inductive drive assembly 353 includes a second inductive drive 3531, the second inductive drive 3531 being configured as a conductor.

In this embodiment, the conductor may be configured as a copper plate, iron, or the like. Since the first induction transmission set 313 and the second induction transmission set 353 are driven by eddy currents, when the inner rotor and the outer rotor of the coupling 30 move relatively, induced current is generated in the conductor, and heat is generated. The second induction transmission set 353 is configured as a conductor, the first induction transmission part is configured as a permanent magnet, and when the pump body works, the internal air flow is favorable for the second induction transmission set 353 to radiate heat. In another embodiment, the first inductive transmission element may be configured as a conductor, and the second inductive transmission element 3531 may be configured as a permanent magnet. In this way, the influence of conductor heat generation on the operation efficiency of the pump body in the vortex transmission can be avoided.

Further, as shown in fig. 4, in an embodiment, the second inductive transmission member 3531 may be configured as a conductive block, and the conductive block is provided with a plurality of conductive blocks, and the second inductive transmission member 3531 is in one-to-one fit with the first inductive transmission member.

In this embodiment, the second inductive driving element 3531 is in one-to-one fit with the first inductive driving element, so that the speed of change of the magnetic flux in each conductor block is increased, and the torque transmitted is increased. In addition, the second inductive transmission member 3531 is configured to guide a plurality of conductor blocks, and is also convenient for replacement and maintenance. In other embodiments, second inductive drive 3531 may be configured as a cage structure, such as in a three-phase ac motor rotor, or as a unitary ring structure.

As shown in fig. 4, in one embodiment, the inner rotor 35 further includes an inner rotor core 355, the second induction transmission group 353 is disposed on the outer periphery of the inner rotor core 355, and the rotor core 355 is axially provided with a through hole for the input shaft 13 to pass through. The inner rotor core can be made of silicon steel sheets, so that the magnetic field strength can be improved, the transmission torque can be improved, the eddy current can be reduced, and the heating can be prevented.

In one embodiment, the magnetizing direction of the first inductive transmission member is radial, and the polarities of the adjacent magnetic poles of the first inductive transmission member are opposite. In this way, the speed of change of the magnetic flux can be increased, thereby increasing the torque transmitted.

As shown in fig. 3, in one embodiment, the outer rotor 31 further includes a first magnetic steel fixing sleeve 315 and a second magnetic steel fixing sleeve 317 connected, the first magnetic steel fixing sleeve 315 is located at the outer periphery of the first permanent magnet group 311, and the second magnetic steel fixing sleeve 317 is located at the outer periphery of the first induction transmission group 313.

By providing the first magnetic steel fixing sleeve 315 and the second magnetic steel fixing sleeve 317, the magnetic field can be enhanced in addition to the fixing of the first permanent magnet group 311 and the first induction transmission group 313. It is readily understood that the first magnetic steel fixing sleeve 315 and the second magnetic steel fixing sleeve 317 are made of magnetically conductive materials. And grooves uniformly distributed along the axial direction can be formed in the first magnetic steel fixing sleeve 315 and the second magnetic steel fixing sleeve 317, wherein the first permanent magnet group 311 and the first induction transmission group 313 can be fixed in the grooves through epoxy glue.

In an embodiment, the outer rotor further includes a fixed connecting sleeve 319, the fixed connecting sleeve 319 includes a first connecting portion 3191 and a second connecting portion 3193, the first connecting portion 3191 is located between the first permanent magnet group 311 and the first induction transmission group 313 and extends along a direction away from the inner rotor 35, the second connecting portion 3193 is fixed at one end of the first connecting portion 3191 away from the first permanent magnet group 311, and two ends of the second connecting portion 3193 along the axial direction respectively abut against the first magnetic steel fixed sleeve 315 and the second magnetic steel fixed sleeve 317.

In this embodiment, the fixed connecting sleeve 319 is located between the first magnetic steel fixing sleeve 315 and the second magnetic steel fixing sleeve 317, and is connected with the first magnetic steel fixing sleeve 315 and the second magnetic steel fixing sleeve 317 respectively, specifically, the fixed connecting sleeve 319 may be welded, bonded or otherwise connected with the first magnetic steel fixing sleeve 315 and the second magnetic steel fixing sleeve 317. The fixed connecting sleeve 319 separates the first permanent magnet group 311 from the first induction transmission group 313, and is pressed against the first magnetic steel fixed sleeve 315 and the second magnetic steel fixed sleeve 317 by the second connecting portion 3193, so that the connecting structure is stable. The fixed connection sleeve 319 is made of a material with low magnetic permeability, such as cast iron and nickel-zinc ferrite material, and the relative magnetic permeability of the fixed connection sleeve can be 10-200. In this way, a stronger radial magnetic field can be formed, and the torque to be transmitted can be improved.

In the embodiment of the application, under the normal working condition, the motor drives the outer rotor of the coupler to rotate, and under the action of the magnetic fields of the first permanent magnet group 311 and the first induction transmission group 313 of the outer rotor, the second permanent magnet group 351 follows the outer rotor to synchronously move, so that the inner rotor and the outer rotor synchronously move. When the transmission torque is larger than the rated torque of the permanent magnet coupler, the first induction transmission group 313 of the outer rotor and the second induction transmission group 353 of the inner rotor rotate relatively, and when the first induction transmission group 313 is configured as a permanent magnet and the second induction transmission group 353 is configured as a conductor, eddy current is generated on the surface of the second induction transmission group 353, and the eddy current can perform torque compensation. When the first induction driving set 313 is configured as a conductor and the second induction driving set 353 is configured as a permanent magnet, eddy currents are generated on the surface of the first induction driving set 313, and the eddy currents can perform moment compensation. Thereby improving the reliability of permanent magnet transmission.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.

In the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more features.

The vacuum pump provided by the embodiment of the present application has been described in detail, and specific examples are applied herein to illustrate the principles and embodiments of the present application, and the above examples are only for helping to understand the method and core idea of the present application; meanwhile, as those skilled in the art will vary in the specific embodiments and application scope according to the ideas of the present application, the present description should not be construed as limiting the present application in summary.

Claims

1. A vacuum pump, comprising:

the pump body comprises a pump shell and an input shaft rotatably arranged on the pump shell;

2. A vacuum pump according to claim 1, wherein a flange portion is fixed to a side of the mounting portion facing the pump housing, the pump housing being fixed with a projection fitted with the flange portion, the flange portion being abutted against a side portion of the projection.

3. A vacuum pump according to claim 1 or 2, wherein the outer rotor comprises a first permanent magnet group and a first induction drive group arranged at intervals, and the inner rotor comprises a second permanent magnet group arranged radially opposite to the first permanent magnet group, and a second induction drive group arranged corresponding to the first induction drive group in a radial direction.

4. A vacuum pump according to claim 3, wherein the first inductive transmission set comprises a plurality of first inductive transmission members configured as permanent magnets; the second inductive drive assembly includes a second inductive drive, the second inductive drive configured as a conductor.

5. A vacuum pump according to claim 4, wherein the second inductive transmission member is configured as a conductor block, and the conductor block is provided in plurality, and the second inductive transmission member is fitted one by one with the first inductive transmission member.

6. The vacuum pump of claim 5, wherein the inner rotor further comprises an inner rotor core, the second inductive drive set is disposed on an outer periphery of the inner rotor core, and the inner rotor core is axially provided with a through hole for the input shaft to pass through.

7. A vacuum pump according to claim 4, wherein the direction of magnetization of the first inductive transfer member is radial and adjacent poles of the first inductive transfer member are of opposite polarity.

8. The vacuum pump of claim 4, wherein the outer rotor further comprises a first magnetic steel fixing sleeve and a second magnetic steel fixing sleeve connected, the first magnetic steel fixing sleeve being located at the periphery of the first permanent magnet group, and the second magnetic steel fixing sleeve being located at the periphery of the first induction transmission group.

9. The vacuum pump of claim 8, further comprising a fixed connection sleeve on the outer rotor, wherein the fixed connection sleeve comprises a first connection portion and a second connection portion, the first connection portion is located between the first permanent magnet group and the first induction transmission group and extends along a direction away from the inner rotor, the second connection portion is fixed at one end of the first connection portion away from the first permanent magnet group, and two ends of the second connection portion along an axial direction respectively abut against the first magnetic steel fixed sleeve and the second magnetic steel fixed sleeve.

10. A vacuum pump according to claim 9, wherein the relative permeability of the fixed connection sleeve is between 10 and 200.