CN107893853B

CN107893853B - Convex step shaft magnetic fluid sealing device

Info

Publication number: CN107893853B
Application number: CN201711326633.1A
Authority: CN
Inventors: 杨小龙; 陈帆; 郝付祥; 孙彭; 何美丽
Original assignee: Guangxi University of Science and Technology
Current assignee: Guangxi University of Science and Technology
Priority date: 2017-12-13
Filing date: 2017-12-13
Publication date: 2021-02-12
Anticipated expiration: 2037-12-13
Also published as: CN107893853A; WO2019114228A1

Abstract

The invention relates to a convex step shaft magnetic fluid sealing device which comprises a shell, a sealing assembly and an end cover, wherein the shell is provided with a sealing assembly; the sealing assembly comprises a shaft which is rotatably arranged in the shell through a bearing, the shaft comprises at least one convex step part, the convex step part comprises a plurality of steps which are sequentially arranged along the axial direction, and the outer walls of the adjacent steps are connected through an arc-shaped inverted-angle-shaped transition surface; each transition surface is sleeved with a pole shoe matched with the transition surface, the pole shoe extends to the position corresponding to the corresponding step on the side part of the transition surface towards one side or two sides of the transition surface, gaps are reserved between the inner wall of the pole shoe and the corresponding transition surface and between the inner wall of the pole shoe and the corresponding step, and the part of the inner wall of the pole shoe and/or the part of the shaft corresponding to the inner wall of the pole shoe is provided with pole teeth; and a permanent magnet is arranged between the adjacent pole shoes. The invention has the advantages of strong pressure resistance, strong secondary pressure bearing capacity and self-repairing capacity, strong pressure resistance and sealing reliability of the magnetic fluid seal under the condition of large clearance and large safe working range.

Description

Convex step shaft magnetic fluid sealing device

Technical Field

The invention relates to a convex step shaft magnetic fluid sealing device, and belongs to the field of mechanical engineering sealing.

Background

The magnetic fluid seal is to seal gas and liquid by means of magnetic fluid seal ring formed by magnetic fluid under the action of strong magnetic field, and because it is contacted and sealed with the seal shaft by means of magnetic fluid, it can prevent direct friction between seal shaft and seal element and reduce additional load, and in addition, it also has the characteristics of zero leakage, high reliability and simple structure, etc. Although the technology of the magnetic fluid on vacuum low-pressure sealing is mature and widely applied, a plurality of problems are not solved on high-pressure gas sealing and liquid sealing, for example, the sealing pressure of the magnetic fluid is too low, the sealed medium can cause the deterioration of the magnetic fluid to cause the rapid failure of the sealing, the sealing difficulty is large, and a certain difference exists from the practical application. Therefore, how to reasonably design the parameters of the magnetic fluid sealing structure, improve the utilization efficiency of the permanent magnet and enhance the sealing pressure resistance is also a significant research content of the current magnetic fluid sealing technology.

One of the methods for improving the pressure resistance of the magnetic fluid seal under a large gap is to increase the number of magnetic sources in the magnetic circuit of the magnetic fluid seal and improve the shape of the pole piece, such as the sealing device described in reference 1 (patent publication No. CN 204805552U) and the sealing device described in reference 2 (patent publication No. CN 202418592U). Although the two sealing devices described in the above documents have greatly improved sealing performance with respect to a common magnetic fluid, there is still room for further improvement in the sealing performance of the existing sealing structure.

The magnetic fluid is not magnetic in a static state, and only shows magnetism under the action of an external magnetic field. The magnetic particles and the carrier liquid are integrated, so that the magnetic fluid has the magnetism of common magnetic materials and the liquidity of liquid, and has a plurality of unique properties.

Compared with the common single magnetic source magnetic fluid seal or the common multi-magnetic source magnetic fluid seal, the existing sealing device increases the strength of magnetic field force, so that the sealing performance is greatly improved, but the requirement of high sealing performance in high-speed and heavy-load occasions cannot be met.

Disclosure of Invention

The invention aims to provide a convex step shaft magnetic fluid sealing device, so that the problem of low pressure resistance of the existing single-magnetic-source magnetic fluid sealing device and multi-magnetic-source magnetic fluid sealing device is solved, and stress concentration is reduced, so that the sealing technology is successfully applied to the fields of high speed and heavy load and the like.

In order to solve the technical problems, the technical scheme of the invention is as follows: a convex step shaft magnetic fluid sealing device comprises a shell with openings at two ends, a sealing assembly and an end cover used for pressing the sealing assembly in the shell; the sealing assembly comprises a shaft which is rotatably arranged in the shell through a bearing, the shaft comprises at least one convex step part, the convex step part comprises a plurality of steps which are sequentially arranged along the axial direction, and the outer walls of the adjacent steps are connected through an arc-shaped inverted-angle-shaped transition surface; each transition surface is sleeved with a pole shoe matched with the transition surface, the pole shoe extends to the position corresponding to the corresponding step on the side part of the transition surface towards one side or two sides of the transition surface, gaps are reserved between the inner wall of the pole shoe and the corresponding transition surface and between the inner wall of the pole shoe and the corresponding step, and the part of the inner wall of the pole shoe and/or the part of the shaft corresponding to the inner wall of the pole shoe is provided with pole teeth; and a permanent magnet is arranged between the adjacent pole shoes.

Further, the outer walls of the adjacent steps are connected through a fillet-shaped transition surface.

Furthermore, the pole shoe and the part corresponding to the fillet-shaped transition surface, and the arc curvature radius of the inner ring surface of the pole shoe is larger than that of the corresponding transition surface on the shaft; furthermore, the arc curvature radius of the inner ring surface of the pole shoe is 3-43 mm; correspondingly, the curvature radius of the arc on the shaft is 2-40 mm.

Further, when the number of steps in a single projecting step portion exceeds 2, the adjacent side magnetic poles of the adjacent permanent magnets distributed in the axial direction are the same.

Further, the pole teeth comprise axial pole teeth and/or transition pole teeth, the axial pole teeth are arranged on the steps and/or the inner walls of the pole shoes corresponding to the steps, and the transition pole teeth are arranged on the transition surfaces and/or the inner walls of the pole shoes corresponding to the transition surfaces.

Preferably, in the single convex step part, the number of the steps is 3-11, the number of the transition surfaces is 2-10, and the number of the pole shoes is 2-10.

As an embodiment of the present invention, the convex step portion includes 1 first step, 2 second steps and 2 third steps, diameters of the first step, the second step and the third step are sequentially reduced, and the 2 second steps and the 2 third steps are sequentially and symmetrically distributed on two sides of the first step.

Further, the size of the gap is 0.05-5mm, preferably 2-5 mm.

Furthermore, the outer wall of the pole shoe is provided with an annular groove, and a sealing ring is arranged in the annular groove.

Furthermore, in the single convex step part, the outer sides of the two pole shoes at the outermost side are respectively provided with a first magnetism isolating ring and a second magnetism isolating ring.

Further, the number of the bearings is two, and the two bearings are respectively a first bearing and a second bearing and are respectively arranged on two sides of the step portion.

Further, the end cover is detachably fixed at the right end of the shell. Preferably, the end cap is fixed to the right end of the housing by screw threads.

The sealing device can solve the problem of insufficient pressure resistance of the sealing device under the condition of large clearance. Through designing a protruding step formula pivot (protruding circular arc stepped shaft) and circular arc formula terminal shoe structure with arc chamfer form transition surface, preferably, equipartition is seted up corresponding shape's utmost point tooth on the radial inner ring face of circular arc formula terminal shoe and the circular arc formula side (the arc face corresponding with arc chamfer form transition surface), imbeds the permanent magnet between the terminal shoe, injects the magnetic current body in the radial and circular arc face direction seal clearance that terminal shoe and protruding circular arc stepped shaft formed to realize a protruding step axle magnetic current body seal. On the basis of stepped magnetic fluid sealing, the structure of the shaft is improved by arranging a multistage magnetic source and improving the distribution form of pole teeth on pole shoes, and a rectangular stepped shaft is improved into a convex arc stepped shaft, so that the sealing pressure resistance of the magnetic fluid is greatly enhanced; the convex arc type sealing structure can reduce the loss of magnetic fluid when the sealing fails, reduce stress concentration, facilitate production and processing, and increase the secondary pressure bearing capacity and self-repairing capacity of the sealing device. Further improves the pressure resistance and the sealing reliability of the magnetic fluid seal under the condition of large clearance and enlarges the safe working range.

In conclusion, the magnetic fluid sealing device has strong pressure resistance and convenient production and processing; when the sealing fails, the loss of the magnetic fluid is small, the secondary pressure bearing capacity and the self-repairing capacity are strong, and the pressure resistance and the sealing reliability of the device under the condition of large clearance are effectively improved, so that the safe working range is expanded.

Drawings

Fig. 1 is a schematic sectional structure view of a magnetic fluid sealing device according to a first embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. For convenience of description, the words "upper", "lower", "left" and "right" in the following description are used only to indicate the correspondence between the upper, lower, left and right directions of the drawings themselves, and do not limit the structure.

As shown in fig. 1, the magnetic fluid sealing device for the convex step shaft comprises a shell 2 with two open ends, a sealing assembly and an end cover 10 for pressing the sealing assembly into the shell 2; the sealing assembly comprises a shaft 1, the shaft 1 is rotatably arranged in a shell 2 through a bearing, the shaft 1 comprises a convex step part 101, the convex step part 101 comprises 5 steps which are sequentially arranged along the axial direction, and the outer walls of the adjacent steps are connected through a fillet transition surface; each transition surface is sleeved with a pole shoe matched with the transition surface, the pole shoe extends to the position corresponding to the corresponding step on the side part of the transition surface from the outside direction of the transition surface (the diameter reducing direction of the transition surface), gaps are reserved between the inner wall of the pole shoe and the corresponding transition surface and step, and pole teeth are arranged on the inner wall of the pole shoe and the part of the shaft 1 corresponding to the inner wall of the pole shoe; and a permanent magnet is arranged between the adjacent pole shoes.

The convex step part 101 comprises 1

first step

1011, 2

second steps

1012 and 2 third steps 1013, the diameters of the first step 1011, the second step 1012 and the third step 1013 are sequentially reduced, and the 2 second steps 1012 and the 2 third steps 1013 are sequentially and symmetrically distributed at two sides of the first step 1011. The adjacent steps are connected through a fillet-shaped transition surface, and a left pole shoe 22, a left pole shoe 19, a right pole shoe 17 and a right pole shoe 15 are respectively sleeved outside the step part from left to right at positions corresponding to the transition surfaces. From left to right, a left permanent magnet 7, a middle permanent magnet 8 and a right permanent magnet 9 are respectively arranged between the adjacent pole shoes, and the adjacent side magnetic poles of the adjacent permanent magnets are the same.

The pole teeth comprise axial pole teeth and transition pole teeth, the axial pole teeth are arranged on the inner wall of the pole shoe corresponding to the step, and the transition pole teeth are arranged on the transition surface. Correspondingly, a first left axial pole tooth 5 is arranged on the inner wall of the left pole shoe 22 corresponding to the third step 1013, and a first left transition pole tooth 6 is arranged on the transition surface corresponding to the left pole shoe 22; the inner wall of the left pole shoe 19 corresponding to the second step 1012 is provided with a second left axial pole tooth, and the transition surface corresponding to the left pole shoe 19 is provided with a second left transition pole tooth. A first right axial pole tooth 11 is arranged on the inner wall of the right pole shoe 15 corresponding to the third step 1013, and a first right transition pole tooth 10 is arranged on the transition surface corresponding to the right pole shoe 15; the inner wall of the right pole shoe 17 corresponding to the second step 1012 is provided with a second right axial pole tooth, and the transition surface corresponding to the right pole shoe 17 is provided with a second right transition pole tooth.

The size of the gap is 3 mm.

The outer wall of the pole shoe is provided with an annular groove, and a sealing ring is arranged in the annular groove. Correspondingly, a left sealing ring 21, a left sealing ring 20, a right sealing ring 18 and a right sealing ring 16 are respectively arranged in annular grooves on the outer walls of the left pole shoe 22, the left pole shoe 19, the right pole shoe 17 and the right pole shoe 15.

In the single convex step part, the outer sides of the two outermost pole shoes are respectively provided with a first magnetism isolating ring 4 and a second magnetism isolating ring 12.

The number of the bearings is two, the two bearings are respectively a first bearing 3 and a second bearing 13 and are respectively arranged at the outer sides of the first magnetism isolating ring 4 and the second magnetism isolating ring 12.

The end cap 14 is detachably fixed to the right end of the housing 2.

During assembly, the method mainly comprises the following steps:

(1) a left sealing ring 21 is arranged in a groove on the outer circular surface of a left pole shoe 22;

a left second sealing ring 20 is arranged in a groove on the outer circular surface of the left second pole shoe 19;

a right two-sealing ring 18 is arranged in a groove on the outer circular surface of the right two-pole shoe 17;

a right sealing ring 16 is arranged in a groove on the outer circular surface of the right pole shoe 15;

(2) the middle permanent magnet 8, the left pole shoe 19, the left permanent magnet 7 and the left pole shoe 22 are sequentially arranged on the shaft 1 from the left side of the shaft;

injecting magnetic fluid into a sealing gap formed by the left pole shoe 22, the left pole shoe 19 and the shaft 1;

a right two-pole shoe 17, a right one-permanent magnet 9 and a right one-pole shoe 15 are sequentially arranged on the shaft 1 from the right side of the shaft;

injecting magnetic fluid into a sealing gap formed by the right two pole shoes 17, the right one pole shoe 15 and the shaft 1;

(3) sequentially installing a first magnetism isolating ring 4 and a first bearing 3 on a shaft 1 from the left side of the shaft;

a second magnetism isolating ring 12 and a second bearing 13 are sequentially arranged on the shaft 1 from the right side of the shaft to form a sealing assembly;

(4) installing the sealing assembly in the shell 2, and tightly pressing the outer ring of the right bearing 13 through the threaded connection of the end cover 14 and the shell 2; the convex step shaft magnetic fluid seal is realized.

The foregoing examples are set forth to illustrate the present invention more clearly and are not to be construed as limiting the scope of the invention, which is defined in the appended claims to which the invention pertains, as modified in all equivalent forms, by those skilled in the art after reading the present invention.

Claims

1. A convex step shaft magnetic fluid sealing device comprises a shell (2) with openings at two ends, a sealing assembly and an end cover (14) used for pressing the sealing assembly in the shell (2); the sealing assembly comprises a shaft (1), the shaft (1) is rotatably arranged in a shell (2) through a bearing, and the sealing assembly is characterized in that the shaft (1) comprises at least one convex step part (101), the convex step part (101) comprises a plurality of steps which are sequentially arranged along the axial direction, and the outer walls of the adjacent steps are connected through a fillet transition surface; each transition surface is externally sleeved with a pole shoe matched with the transition surface, the pole shoe extends to the position corresponding to the corresponding step on the side part of the transition surface towards one side or two sides of the transition surface, gaps are reserved among the inner wall of the pole shoe, the corresponding transition surface and the corresponding step, the size of each gap is 2-5mm, and the inner wall of the pole shoe and the part of the shaft (1) corresponding to the inner wall of the pole shoe are provided with pole teeth; a permanent magnet is arranged between the adjacent pole shoes; the pole teeth comprise axial pole teeth and transition pole teeth, the axial pole teeth are arranged on the steps and the inner walls of the pole shoes corresponding to the steps, and the transition pole teeth are arranged on the transition surfaces and the inner walls of the pole shoes corresponding to the transition surfaces; the convex step part (101) comprises 1 first step (1011), 2 second steps (1012) and 2 third steps (1013), the diameters of the first step (1011), the second step (1012) and the third step (1013) are sequentially reduced, and the 2 second steps (1012) and the 2 third steps (1013) are sequentially and symmetrically distributed on two sides of the first step (1011).

2. The convex stepped shaft magnetic fluid seal device according to claim 1, wherein adjacent side poles of adjacent permanent magnets distributed in the axial direction are the same when the number of steps exceeds 2.

3. The convex stepped shaft magnetofluid sealing device of claim 1, wherein an annular groove is formed in an outer wall of the pole shoe, and a sealing ring is arranged in the annular groove.

4. The magnetic fluid sealing device for the convex stepped shaft as claimed in claim 1, wherein the outer sides of the two outermost pole shoes in the single convex stepped part are respectively provided with a first magnetism isolating ring (4) and a second magnetism isolating ring (12).

5. A convex stepped shaft magnetic fluid sealing device according to claim 1, characterised in that the number of said bearings is two, being a first bearing (3) and a second bearing (13), respectively, and being arranged on both sides of the convex stepped portion, respectively.

6. A stepped shaft mhd seal according to claim 1 wherein the end cap (14) is removably secured to the right end of the housing (2).