CN114838134A

CN114838134A - Multi-pole tooth magnetic liquid sealing device

Info

Publication number: CN114838134A
Application number: CN202210349676.6A
Authority: CN
Inventors: 李德才; 李倩
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-04-02
Filing date: 2022-04-02
Publication date: 2022-08-02

Abstract

The invention provides a multi-pole-tooth magnetic liquid sealing device which comprises a cylinder body, a rotating shaft, pole shoes, magnetic liquid and permanent magnets, wherein the cylinder body is provided with a shell and a containing cavity, the rotating shaft is arranged on the shell and penetrates through the containing cavity, the pole shoes are sleeved on the rotating shaft and are arranged in the containing cavity, the permanent magnets are arranged among the pole shoes and surround the rotating shaft, main pole teeth and tooth grooves positioned between the adjacent main pole teeth are arranged on the inner sides of the pole shoes, the rotating shaft is provided with a shaft part and auxiliary pole teeth, the auxiliary pole teeth are convexly arranged on the shaft part and annularly surround the shaft part, the main pole teeth face the shaft part, the auxiliary pole teeth are positioned in the tooth grooves, the magnetic liquid is positioned between the main pole teeth and the shaft part and between the auxiliary pole teeth and the inner walls of the tooth grooves, and as the main pole teeth and the auxiliary pole teeth are arranged in a crossed manner, the multi-pole-tooth magnetic liquid sealing device has good sealing performance, strong pressure resistance and self-recovery performance.

Description

Multi-pole tooth magnetic liquid sealing device

Technical Field

The invention belongs to the field of mechanical engineering sealing, and particularly relates to a multi-pole-tooth magnetic liquid sealing device.

Background

The magnetic liquid sealing technology has the advantages of zero leakage, strong reliability, simple structure, long service life, no abrasion and recoverability, is widely applied to the industrial field, and particularly has the advantage that the zero leakage is incomparable with other sealing forms. However, due to the limitations of magnetic energy product of a magnetic source, the saturation magnetization of the pole shoe material and the magnetic liquid, the pressure resistance of one pole tooth of the magnetic liquid sealing device is limited, about 0.2MPa, and although the pressure resistance of the magnetic liquid sealing device can be increased by increasing the number and the number of the pole teeth of the magnetic liquid sealing device, the pressure resistance of the magnetic liquid sealing device is still limited due to the limitation of space length and the like, and generally does not exceed 3 MPa.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, an object of the present invention is to provide a multi-pole-tooth magnetic liquid sealing device with good sealing effect and strong pressure resistance.

The utility model provides a multipolar tooth magnetic liquid sealing device, includes cylinder body, pivot, pole shoe, magnetic liquid, permanent magnet, the cylinder body has shell and holds the chamber, the pivot install in on the shell and run through hold the chamber, the pole shoe cover is located in the pivot and install in hold the intracavity, the permanent magnet is installed in a plurality of between the pole shoe and encircle the pivot, the inboard of pole shoe has main utmost point tooth and is located adjacently tooth's socket between the main utmost point tooth, the pivot has axial region and attaches utmost point tooth, attach utmost point tooth protruding locate on the axial region and be the annular and encircle the axial region, main utmost point tooth orientation the axial region, attach utmost point tooth and be located in the tooth's socket, magnetic liquid be located main utmost point tooth with between the axial region and attach utmost point tooth with between the inner wall of tooth's socket.

Furthermore, the pole shoe is of a split structure and is formed by fixing a plurality of sub pole shoes.

Further, the rotating shaft further comprises an annular boss protruding from the shaft portion, the boss has an outer peripheral wall and two side walls connecting the outer peripheral wall and the shaft portion, and the auxiliary pole teeth are located on the outer peripheral wall and the two side walls.

Further, attach the utmost point tooth and include first utmost point tooth and second utmost point tooth, first utmost point tooth is located on the periphery wall, second attaches the utmost point tooth and distributes on two lateral walls, on two lateral walls the second attaches the utmost point tooth symmetry setting.

Further, a plurality of second auxiliary pole teeth are arranged on the two side walls.

Further, in the axial direction, a thickness of the first additional pole tooth is smaller than a thickness of the pillow block.

Further, the multi-pole-tooth magnetic liquid sealing device further comprises bearings, the rotating shaft further comprises a collar protruding on the shaft portion, and the collar abuts against between two adjacent bearings.

Furthermore, the bearing is of a split structure and is formed by fixing a plurality of sub-bearings, and sealant is arranged at the joints of the sub-bearings; and/or the shell is of a split structure, the shell is provided with an upper shell and a lower shell, the upper shell is fixed on the lower shell in a threaded connection mode, and the upper shell and the lower shell jointly form the containing cavity.

Further, the multi-pole-tooth magnetic liquid sealing device further comprises bearings, a sleeve is mounted on the rotating shaft, and the sleeve abuts against between every two adjacent bearings.

Further, a first gap is formed between the tooth crest of the main pole tooth and the shaft part, a second gap is formed between the tooth crest of the auxiliary pole tooth and the inner wall of the tooth groove, and the distance between the first gap and/or the second gap is 0.01-1 mm.

The multi-pole-tooth magnetic liquid sealing device is provided with the pole shoe and the rotating shaft, the pole shoe is provided with the main pole teeth and the tooth grooves positioned between the adjacent main pole teeth, the rotating shaft is provided with the auxiliary pole teeth, the auxiliary pole teeth are positioned in the tooth grooves, and the main pole teeth and the auxiliary pole teeth are arranged in a crossed manner, so that when the multi-pole-tooth magnetic liquid sealing device is operated at a high speed, even if the magnetic liquid between the main pole teeth and the rotating shaft is thrown into the tooth grooves, the magnetic liquid can be adsorbed between the auxiliary pole teeth and the inner walls of the tooth grooves under the action of magnetic force, the sealing performance of the magnetic liquid is ensured, and the sealing effect of the magnetic liquid sealing device is improved; in addition, the magnetic liquid is adsorbed between the main pole teeth and the shaft portion and between the auxiliary pole teeth and the inner wall of the tooth groove, so that the pressure resistance and the self-recovery capability of the multi-pole-tooth magnetic liquid sealing device can be improved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic cross-sectional view of a multi-pole tooth magnetic fluid seal assembly according to a first embodiment of the present invention;

FIG. 2 is a perspective view of the spindle of FIG. 1;

FIG. 3 is a front side view of the bearing of FIG. 1;

FIG. 4 is an enlarged view of a portion IV of FIG. 1;

FIG. 5 is a schematic cross-sectional view of a multi-pole tooth magnetic fluid seal assembly in accordance with a second embodiment of the present invention;

FIG. 6 is a perspective view of the spindle of FIG. 5;

fig. 7 is a partial enlarged view of VII portion in fig. 5.

Detailed Description

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention. Furthermore, the terms "first", "second" and "first" 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 defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

Referring to fig. 1, fig. 1 shows a schematic diagram of a multi-pole tooth magnetic liquid sealing device 100 according to a first embodiment of the present invention, where the multi-pole tooth magnetic liquid sealing device 100 includes a cylinder 10, a rotating shaft 20, a bearing 30, a pole shoe 40, a permanent magnet 50, and a magnetic liquid 60.

The cylinder body 10 comprises a shell 11, a containing cavity 12 and a detachable end cover 13, wherein the containing cavity 12 is located in the shell 11, and the end cover 13 can be fixed at the end part of the shell 11 and covers the containing cavity 12. The housing 11 is a split structure and includes an upper shell 11a and a lower shell 11b, and the upper shell 11a and the lower shell 11b can be fixed in a threaded connection manner. Further, a first sealing element is disposed at a joint of the upper shell 11a and the lower shell 11b to ensure good sealing performance, and the first sealing element may be a sealing adhesive or a sealing rubber, which is not limited herein, so as to achieve the desired sealing performance.

Referring to fig. 2, the rotating shaft 20 has magnetic conductivity, and can be fixed to the housing 11 and penetrate through the cavity 12, the rotating shaft 20 has a cylindrical shaft portion 21 and an additional pole tooth 22 protruding on the shaft portion 21, and the additional pole tooth 22 is annularly disposed around the shaft portion 21. Preferably, the shaft portion 21 is provided with a plurality of the additional pole teeth 22 at intervals in parallel.

The rotating shaft 20 further includes a collar 23 protruding from the shaft 21, the collar 23 is used to space the bearings 30 to prevent the bearings 30 from shifting toward each other during high-speed operation, and the collar 23 is disposed around the shaft 21. The rotating shaft 20 can be made of a magnetic conductive material directly; the shaft 20 may also be made of a composite of multiple materials, for example, the inside of the shaft 20 may be made of a non-magnetic material, and the outside may be made of a magnetic material.

Referring to fig. 3, the bearing 30 is a split design, that is, the bearing 30 is formed by fixing a plurality of sub-bearings. For example, the bearing 30 has a first sub-bearing 31 and a second sub-bearing 32, and the first sub-bearing 31 may be fixed to the second sub-bearing 32 by a screw connection. In the present embodiment, the bearing 30 is formed by fixedly connecting two sub-bearings, but the bearing 30 may be formed by fixedly connecting other number of sub-bearings, such as three or four. Further, a second sealing element is arranged at the joint of the multi-segment sub-bearing to achieve good sealing performance, and the second sealing element can be sealant or sealing rubber, which is not limited herein and is suitable for achieving the required sealing performance.

Referring to fig. 4, a plurality of main pole teeth 41 are formed on the inner side of the pole shoe 40, and a tooth slot 42 is formed between two adjacent main pole teeth 41, wherein the width of the tooth slot 42 is greater than the width of the auxiliary pole tooth 22, so that a sealing gap exists between the tooth slot 42 and the auxiliary pole tooth 22 in the radial direction. The pole shoe 40 is a split structure and is formed by fixing a plurality of sections of sub pole shoes. In particular, the pole shoe 40 has a first and a

second sub-pole shoe

40a, 40b, the inside of the first and

second sub-pole shoes

40a, 40b having the main pole teeth 41 and the tooth slots 42. Although the present embodiment only illustrates that the pole shoe 40 is formed by two sub-pole shoes, those skilled in the art will appreciate that the pole shoe 40 may be formed by splicing a greater number of sub-pole shoes, such as three, four, etc. Further, a third sealing element is arranged at the connection position of the multiple sections of the sub pole shoes to achieve good sealing performance, and the third sealing element can be sealing glue or sealing rubber, which is not limited herein and is suitable for achieving the required sealing performance.

In order to further improve the sealing effect, a sealing ring 43 is further installed on the outer periphery of the pole shoe 40, and the sealing ring 43 may be an integral structure or may be formed by splicing multiple segments. Preferably, the sealing ring 43 is made of a rubber material.

The permanent magnet 50 annularly surrounds the rotating shaft 20. In one embodiment, the permanent magnet 50 is a circular ring-shaped permanent magnet, and for convenience of installation, the inner diameter of the permanent magnet 50 is greater than the maximum outer diameter of the rotating shaft 20; in another embodiment, the permanent magnet 50 is a plurality of cylindrical permanent magnets arranged in parallel.

The multi-pole-tooth magnetic liquid sealing assembly 100 further comprises a magnetism isolating ring 70, the magnetism isolating ring 70 is arranged in the cavity 12, the magnetism isolating ring 70 is made of a non-magnetic conducting material, and the inner diameter of the magnetism isolating ring 70 is larger than the maximum outer diameter of the rotating shaft 20.

During assembly, the second sub-bearing 32 and the second sub-pole piece 40b are installed in the lower shell 11b, the rotating shaft 20 on which the magnetism isolating ring 70 and the permanent magnet 50 are installed is installed on the second sub-bearing 32 and the second sub-pole piece 40b, the collar 23 abuts against between two adjacent second sub-bearings 32, the magnetism isolating ring 70 abuts against between the second sub-bearing 32 and the second sub-pole piece 40b, and the permanent magnet 50 abuts against between two adjacent second sub-pole pieces 40 b. It should be noted that, in the present installation method, a circular permanent magnet is used for illustration, and those skilled in the art can understand that, when a plurality of cylindrical permanent magnets arranged in parallel are used as the permanent magnet 50, the permanent magnet 50 needs to be installed between adjacent pole shoes 40 first.

The first sub-bearing 31 is screwed to the second sub-bearing 32, and the first sub-pole piece 40a is screwed to the second sub-pole piece 40 b. The bearings 30 and the pole shoes 40 are mounted on the rotating shaft 20, the collar 23 abuts between two adjacent bearings 30, the magnetism isolating ring 70 abuts between the bearings 30 and the pole shoes 40, the permanent magnet 50 abuts between two adjacent pole shoes 40, and the additional pole teeth 22 are located in the tooth slots 42. A first gap L1 is formed between the tooth top of the main pole tooth 41 and the shaft 21, and a second gap L2 is formed between the tooth top of the auxiliary pole tooth 42 and the inner wall of the tooth slot 42, preferably, the distance between the first gap L1 and/or the second gap L2 is 0.01-1 mm.

The magnetic liquid 60 is injected, and the magnetic liquid 60 is filled in the first gap L1 and the second gap L2 under the action of magnetic force.

And locking the upper shell 11a on the lower shell 11b, wherein the upper shell 11a and the lower shell 11b together form the cavity 12, and the installation of the shell 11 is completed. The other magnetism isolating ring 70 is sleeved on the rotating shaft 20, the end cover 13 is locked on the housing 11 and covers the cavity 12, the spacing ring 70 abuts against between the pole shoe 40 and the end cover 13, so far, the assembly of the multi-pole tooth magnetic liquid sealing device 100 is completed, the rotating shaft 20 is installed on the housing 11 and penetrates through the cavity 12, the bearing 30, the pole shoe 40, the permanent magnet 50 and the magnetism isolating ring 70 are installed on the rotating shaft 20 and fixed in the cavity 12, and the magnetic liquid 60 is filled between the main pole tooth 41 and the shaft portion 21 and between the auxiliary pole tooth 23 and the inner wall of the tooth groove 42.

In the traditional magnetic liquid sealing device, only the main pole teeth are arranged on the pole shoes, the magnetic liquid is filled between the main pole teeth and the rotating shaft, and when the magnetic liquid sealing device runs at a high speed, the magnetic liquid at the main pole teeth is greatly thrown out of the tooth grooves due to the action of centrifugal force, so that the magnetic liquid sealing device fails. In the multi-pole-tooth magnetic liquid sealing device 100 provided by the invention, the auxiliary pole teeth 22 are arranged on the rotating shaft 20, the auxiliary pole teeth 22 are positioned in the tooth grooves 42, and the main pole teeth 41 and the auxiliary pole teeth 22 are arranged in a crossed manner, so that the magnetic liquid 60 can be attracted between the auxiliary pole teeth 22 and the inner walls of the tooth grooves 42 under the action of magnetic force even if the magnetic liquid 60 is thrown into the tooth grooves 42 during high-speed operation, thereby ensuring the effect and reliability of magnetic sealing; furthermore, the magnetic fluid 60 is absorbed between the main pole teeth 41 and the shaft portion 21 and between the auxiliary pole teeth 22 and the inner wall of the tooth groove 42, and the pressure resistance of the multi-pole-tooth magnetic fluid sealing device 100 can be improved without increasing the axial length of the magnetic fluid sealing device; in addition, when the magnetic liquid seal fails (namely when the pressure of the seal cavity exceeds the pressure resistance of the magnetic liquid seal, the pressure of the magnetic liquid seal at the moment is called as the seal critical pressure), only a small amount of magnetic liquid is blown away by airflow due to the adsorption and blocking effects of the multi-pole teeth on the magnetic liquid, and the multi-pole teeth magnetic liquid seal (compared with the traditional magnetic liquid seal) has a good self-recovery effect, namely the multi-pole teeth magnetic liquid seal still has strong pressure resistance at the moment, but the seal critical pressure resistance is slightly reduced. .

The types of the bearings 30 may be the same, or different types of bearings may be selected according to the stress condition under the actual working condition.

In the present embodiment, the shaft portion 21 is integrally formed with the collar 23 for spacing the plurality of bearings 30, and alternatively, the collar 23 may be replaced with a detachable sleeve, so that the bearings 30 may be integrally formed without difficulty in mounting, thereby not only ensuring the structural stability of the bearings 30, but also improving the reliability of the multi-pole-tooth magnetic liquid seal device 100.

Although the housing 11 is a separate structure in the present embodiment, it should be understood by those skilled in the art that the housing 11 may be integrally formed.

Fig. 5 shows a schematic view of a multi-pole tooth magnetic fluid seal device 200 according to a second embodiment of the present invention, which differs from the multi-pole tooth magnetic fluid seal device 100 according to the first embodiment in the structure of the rotating shaft 20.

Referring to fig. 6 to 7, the rotating shaft 20 further includes a boss 24 protruding from the shaft 21, and the boss 24 is annularly disposed around the shaft 21. The pillow block 24 has an outer peripheral wall 241 and two side walls 242 connecting the outer peripheral wall 241 and the shaft portion 21, the outer peripheral wall 241 is parallel to the axis of the rotating shaft 20, and the two side walls 242 are perpendicular to the axis of the rotating shaft 20.

The rotating shaft 20 is further provided with the auxiliary pole teeth 22, and the auxiliary pole teeth 22 are located on the outer circumferential wall 241 and the side wall 242. Specifically, the additional pole tooth 22 includes a first additional pole tooth 221 and a second additional pole tooth 222, the first additional pole tooth 221 and the second additional pole tooth 222 are both annular, and the center lines of the first additional pole tooth 221 and the second additional pole tooth 222 are coincident with the axis of the rotating shaft 20.

The first additional pole tooth 221 is located on the peripheral wall 241, and the second additional pole tooth 222 is located on the side wall 242. Preferably, in the axial direction, the thickness of the first additional pole tooth 221 is smaller than that of the pillow block 24, a plurality of second additional pole teeth 222 may be disposed on the side wall 242, the center lines of the plurality of second additional pole teeth 222 coincide, and the second additional pole teeth 222 on the two side walls 242 are symmetrically disposed.

After the rotating shaft 20 is mounted to the cylinder 10, the second gap L2 is formed between the tooth tip of the first additional tooth 221 and the inner wall of the tooth slot 412, a third gap L3 is directly formed between the tooth tip of the second additional tooth 222 and the inner wall of the tooth slot 412, and the magnetic liquid 60 is filled in the second gap L2 and the third gap L3. Unlike the first embodiment, the additional pole tooth 22 of the second embodiment includes the first additional pole tooth 221 and the second additional pole tooth 222, and the main pole tooth 41 and the additional pole tooth 22 are combined to form a structure arranged along the axial direction and the radial direction, so that the sealing effect and the pressure resistance of the multi-pole-tooth magnetic liquid sealing device 100 are greatly improved.

In the multi-pole-tooth magnetic liquid sealing device, the pole shoe 40 is provided with the main pole tooth 41, the rotating shaft 20 is provided with the auxiliary pole teeth 22, and the main pole tooth 41 and the auxiliary pole teeth 22 are arranged in a crossed manner, so that the magnetic liquid 60 can be adsorbed between the auxiliary pole teeth 22 and the inner wall of the tooth groove 412 under the action of magnetic force even if thrown into the tooth groove 412 in high-speed operation, the sealing performance of the magnetic liquid is ensured, and the sealing effect and the reliability of the magnetic liquid sealing device are improved; in addition, the magnetic liquid 60 is absorbed between the main pole tooth 41 and the shaft portion 21 and between the additional pole tooth 22 and the inner wall of the tooth groove 412, and the pressure resistance and the self-recovery performance of the multi-pole magnetic liquid sealing device can be improved. When the shell 11, the bearing 30 or the pole shoe 40 adopt a split structure, a sealing element is arranged at the split joint, so that the leakage of the magnetic liquid 60 from the split joint is avoided, and the sealing performance is ensured.

In the description herein, references to the description of the terms "some embodiments," "optionally," "further," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. The utility model provides a multipolar tooth magnetic liquid sealing device, includes cylinder body, pivot, pole shoe, magnetic liquid and permanent magnet, the cylinder body has shell and holds the chamber, the pivot install in on the shell and run through hold the chamber, the pole shoe cover is located in the pivot and install in hold the intracavity, the permanent magnet is installed in a plurality of between the pole shoe and encircle pivot its characterized in that: the inside of pole shoe has the main pole tooth and is located adjacent tooth's socket between the main pole tooth, the pivot has axial region and attaches the utmost point tooth, attach utmost point tooth protruding locate on the axial region and be the annular and encircle the axial region, the main pole tooth is towards the axial region, attach utmost point tooth is located in the tooth's socket, magnetic fluid is located between the main pole tooth with the axial region and attach utmost point tooth with the inner wall of tooth's socket.

2. The multi-pole tooth magnetic fluid seal of claim 1, wherein: the pole shoe is of a split structure and is formed by fixing a plurality of sub pole shoes.

3. The multi-pole tooth magnetic liquid seal device of claim 1 or 2, wherein: the pivot is still including protruding locating annular pillow block on the axial region, the pillow block has the periphery wall and connects the periphery wall with two lateral walls of axial region, attach the utmost point tooth and be located the periphery wall reaches on two lateral walls.

4. The multi-pole tooth magnetic fluid seal of claim 3, wherein: the auxiliary pole teeth comprise first auxiliary pole teeth and second auxiliary pole teeth, the first auxiliary pole teeth are located on the peripheral wall, the second auxiliary pole teeth are distributed on the two side walls, and the second auxiliary pole teeth are symmetrically arranged on the two side walls.

5. The multi-pole tooth magnetic fluid seal of claim 4, wherein: the two side walls are provided with a plurality of second auxiliary pole teeth.

6. The multi-pole tooth magnetic fluid seal of claim 4, wherein: in the axial direction, a thickness of the first additional pole tooth is smaller than a thickness of the pillow block.

7. The multi-pole tooth magnetic fluid seal of claim 3, wherein: the multi-pole-tooth magnetic liquid sealing device further comprises bearings, the rotating shaft further comprises a shaft collar protruding on the shaft portion, and the shaft collar abuts against between two adjacent bearings.

8. The multi-pole tooth magnetic fluid seal of claim 7, wherein: the bearing is of a split structure and is formed by fixing a plurality of sub-bearings; and/or the shell is of a split structure, the shell is provided with an upper shell and a lower shell, the upper shell is fixed on the lower shell in a threaded connection mode, and the upper shell and the lower shell jointly form the containing cavity.

9. The multi-pole tooth magnetic fluid seal of claim 3, wherein: the multi-pole-tooth magnetic liquid sealing device further comprises bearings, sleeves are mounted on the rotating shafts, and the sleeves are abutted between the two adjacent bearings.

10. The multi-pole tooth magnetic fluid seal of claim 1, wherein: a first gap is formed between the tooth crest of the main pole tooth and the shaft part, a second gap is formed between the tooth crest of the auxiliary pole tooth and the inner wall of the tooth groove, and the distance between the first gap and/or the second gap is 0.01-1 mm.