CN108980358A - A kind of ladder pole flute profile magnetic fluid sealing structure - Google Patents

Abstract

The invention discloses a stepped pole-tooth type magnetic fluid sealing structure. A plurality of ring-shaped pole shoes are arranged at intervals along the axial direction in the space between the outer surface of the reciprocating shaft and the inner wall of the casing. An axially magnetized permanent magnet ring is interposed, and the magnetic poles of the adjacent axially magnetized permanent magnet rings have opposite polarities, and the outer circular surface of the reciprocating shaft is surrounded by a first pole tooth at the position corresponding to the pole shoe. There is a gap between the first pole tooth and the inner surface of the pole piece, and the gap is filled with magnetic fluid; each pole piece corresponds to a plurality of first pole teeth, and all the first pole teeth corresponding to the same pole piece The outer diameters of the teeth are the same; from the high pressure side to the low pressure side, the outer diameters of the first pole teeth corresponding to different pole pieces increase sequentially. In the present invention, the first pole teeth are designed to have a structure with a certain gradient distribution, which can effectively avoid the loss of magnetic fluid when the seal fails, and ensure the pressure resistance performance of the seal.

Description

A stepped pole-tooth type magnetic fluid seal structure

technical field

The invention belongs to mechanical engineering sealing technology, in particular to a stepped pole-tooth type magnetic fluid sealing structure.

Background technique

The existing magnetic fluid sealing structure for reciprocating shafts generally includes a housing with a hollow cavity, a reciprocating shaft, permanent magnets and pole shoes are arranged between the reciprocating shaft and the housing for magnetic fluid sealing, and pole teeth are provided on the inner ring of the pole shoes.

One of the methods to improve the pressure resistance performance of the magnetic fluid seal 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 the patents with publication numbers CN204805552U and CN202418592U. Although the sealing performance of the two sealing devices described in the above documents has been greatly improved compared with ordinary magnetic fluid, the prior art still has the following defects:

The leakage of the magnetic fluid in the magnetic fluid seal leads to the reduction of the magnetic field strength in the magnetic circuit, thereby reducing the pressure resistance of the magnetic fluid seal.

Contents of the invention

In view of the above problems, the present invention aims to provide a stepped-tooth-type magnetic fluid sealing structure capable of reducing the loss of magnetic fluid and having a strong seal pressure resistance.

The technical solution to the problem of the present invention is: a stepped pole-tooth type magnetic fluid sealing structure, including a hollow shell, one end of the shell is closed, the other end is open, a through hole is opened in the center of the closed end face of the shell, and It includes a reciprocating shaft that penetrates from the through hole to the inner cavity of the housing. In the space between the outer surface of the reciprocating shaft and the inner wall of the housing, a plurality of annular pole shoes are arranged at intervals along the axial direction. An axially magnetized permanent magnet ring is provided. The magnetic poles of adjacent axially magnetized permanent magnet rings have opposite polarities. The outer circular surface of the reciprocating shaft is surrounded by a first pole tooth at the position corresponding to the pole piece. There is a gap between a pole tooth and the inner surface of the pole piece, and the gap is filled with magnetic fluid;

There are multiple first pole teeth corresponding to each pole shoe, and the outer diameters of all the first pole teeth corresponding to the same pole shoe are the same;

From the high-voltage side to the low-pressure side, the outer diameters of the first pole teeth corresponding to different pole shoes increase sequentially.

In the above scheme, the first pole tooth is designed to have a structure with a certain gradient distribution. Once the magnetic fluid is lost, it will only flow to the pole tooth with a higher gradient in the next level, thereby being blocked from further loss, which can effectively avoid the failure of the seal. The loss of magnetic fluid ensures the sealing and pressure resistance performance.

The number of the pole shoes is preferably 2-20.

Further, second pole teeth are provided on the inner circular surfaces of the two pole shoes closest to the closed end and the open end of the housing, and the first pole teeth are not provided on the outer circular surfaces of the reciprocating shaft corresponding to the two pole shoes. There is a gap between the second pole tooth and the outer circular surface of the reciprocating shaft, and the gap is filled with magnetic fluid. The number of the pole shoes is 4-20.

For the two pole pieces closest to the closed end and the open end of the housing, the pole teeth can be opened on the pole piece or the shaft, but it is better to process on the pole piece.

Furthermore, there are grooves on the side end surfaces of the two pole pieces closest to the closed end and the open end of the housing, and radially magnetized permanent magnet rings are arranged in the grooves, and the radially magnetized permanent magnet rings The direction of the magnetic field is the same as the direction of the magnetic circuit in which it is located.

In the above further improved solution, the arrangement of the radially magnetized permanent magnet ring in the magnetic circuit is beneficial to further enhance the magnetic field strength and improve the sealing pressure resistance capability.

Further, the relative movement distance between each pole piece and its corresponding first pole tooth does not exceed the total span of the corresponding first pole tooth.

The total span refers to the distance between two first pole teeth at both ends among all the first pole teeth corresponding to the pole piece.

Since the reciprocating shaft is in a reciprocating linear motion, the pole piece will move relative to the first pole tooth, but it cannot exceed the span of the corresponding first pole tooth, otherwise it will happen that it is not relative to the first pole tooth or not with the first pole tooth. The case where the pole teeth of the next rung interfere.

Preferably, the first pole teeth are equally spaced.

Further, a hollow magnetic isolation sleeve is sleeved on the inner wall of the housing, and the outer circular surfaces of all the pole pieces and the axially magnetized permanent magnet ring abut against the inner wall of the magnetic isolation sleeve. The use of the magnetic isolation sleeve can shorten the path length of the magnetic circuit and increase the magnetic field strength in the gap.

Further, the pole piece closest to the open end of the housing is compressed and sealed in the inner chamber of the housing through the end cover.

Notable effect of the present invention is:

1. The first pole tooth is designed to have a structure with a certain gradient distribution. Once the magnetic fluid is lost, it will only flow to the next level of higher gradient pole teeth, thereby being blocked from further loss, which can effectively avoid the magnetic fluid when the seal fails The loss of the seal ensures the pressure resistance performance of the seal.

2. The addition of a radially magnetized permanent magnet ring is conducive to further enhancing the magnetic field strength and improving the sealing pressure resistance.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is a schematic diagram of the magnetic fluid seal structure of the present invention.

In the figure: 1-reciprocating shaft, 2-housing, 3-pole shoe, 4-end cover, 5-magnetic isolation sleeve, 6-first pole tooth, 7-axial magnetized permanent magnet ring, 8-diameter Magnetized permanent magnet ring, 10-second pole teeth.

Detailed ways

As shown in FIG. 1 , a stepped-tooth magnetic fluid sealing structure includes a hollow housing 2 , one end of which is closed and the other end is open. A through hole is opened in the center of the closed end face of the housing 2 . It also includes a reciprocating shaft 1 penetrating from the through hole to the inner cavity of the housing 2 .

In the space between the outer surface of the reciprocating shaft 1 and the inner wall of the housing 2, a plurality of annular pole pieces 3 are axially spaced apart. An axially magnetized permanent magnet ring 7 is sandwiched between two adjacent pole pieces 3 . The polarities of the magnetic poles of adjacent axially magnetized permanent magnet rings 7 are opposite. A hollow magnetic isolation sleeve 5 is sleeved on the inner wall of the housing 2 . The outer circular surfaces of all the pole pieces 3 and the axially magnetized permanent magnet ring 7 abut against the inner wall of the magnetic isolation sleeve 2 . The pole piece 3 closest to the open end of the housing 2 is compressed and sealed in the inner cavity of the housing 2 through the end cover 4 .

Second pole teeth 10 are provided on the inner circular surfaces of the two pole shoes 3 closest to the closed end and the open end of the housing 2 . There is a gap between the second pole tooth 10 and the outer surface of the reciprocating shaft 1 . The gap between the second pole tooth 10 and the outer surface of the reciprocating shaft 1 is 0.05-3mm. The gap is filled with magnetic fluid.

A first pole tooth 6 is provided around the outer circular surface of the reciprocating shaft 1 and corresponding to other pole shoes 3 (except the two pole shoes 3 closest to the closed end and the open end of the housing 2 ). There is a gap between the first pole tooth 6 and the inner circular surface of the pole piece 3 . The size of the gap between the first pole tooth 6 and the inner surface of the pole shoe 3 is 0.05-3mm. The gap is filled with magnetic fluid.

There are multiple first pole teeth 6 corresponding to each pole piece 3 . The outer diameters of all the first pole teeth 6 corresponding to the same pole shoe 3 are the same.

The first pole teeth 6 are equally spaced.

From the high pressure side to the low pressure side, the outer diameters of the first pole teeth 6 corresponding to different pole shoes 3 increase sequentially. The relative movement distance between each pole shoe 3 and its corresponding first pole tooth 6 does not exceed the total span of the first pole tooth 6 corresponding to the pole shoe 3 .

Grooves are formed on the side end surfaces of the two pole pieces 3 closest to the closed end and the open end of the housing 2 . A radially magnetized permanent magnet ring 8 is arranged in the groove, and the magnetic field direction of the radially magnetized permanent magnet ring 8 is the same as the direction of the magnetic circuit where it is located.

The number of the pole shoes 3 is preferably 4-20.

Claims (9)

1. a kind of ladder pole flute profile magnetic fluid sealing structure, including hollow shell (2), the shell (2) is closed at one end, another End is opened wide, and is provided with through-hole at the closed end center of shell (2), is further included being worn from through-hole to the reciprocal axis of shell (2) inner cavity It is (1), axially spaced in the space between reciprocal axis (1) outer surface and shell (2) inner wall to be equipped with multiple cyclic annular pole shoes (3), Axial charging type permanent-magnetic clamp (7) is folded between two neighboring pole shoe (3), the magnetic pole of adjacent axial charging type permanent-magnetic clamp (7) Polarity is opposite, it is characterised in that: it is equipped with the first pole tooth (6) at the periphery of reciprocal axis (1) and corresponding pole shoe (3) position, There are gap between first pole tooth (6) and the inner headed face of pole shoe (3), gap location is marked with magnetic fluid；

First pole tooth (6) quantity corresponding to each pole shoe (3) has multiple, all first corresponding to the same pole shoe (3) The outer diameter of pole tooth (6) is identical；

From high-pressure side to low pressure side direction, the outer diameter of the first pole tooth (6) corresponding to different pole shoes (3) is successively increased.

2. ladder pole flute profile magnetic fluid sealing structure according to claim 1, it is characterised in that: near shell (2) The inner headed face of two pole shoes (3) of closed end and open end is equipped with the second pole tooth (10), and corresponding to the two pole shoes (3) It is not provided with the first pole tooth (6) at the periphery of reciprocal axis (1), between existing between the second pole tooth (10) and reciprocal axis (1) periphery Gap, gap location are marked with magnetic fluid.

3. ladder pole flute profile magnetic fluid sealing structure according to claim 1 or 2, it is characterised in that: near shell (2) it is provided with groove on the side end face of two pole shoes (3) of closed end and open end, radial magnetizing type permanent-magnetic clamp is provided in groove (8), and the magnetic direction of radial magnetizing type permanent-magnetic clamp (8) is identical as the magnetic loop direction where it.

4. ladder pole flute profile magnetic fluid sealing structure according to claim 1 or 2, it is characterised in that: each pole shoe (3) With its corresponding to the first pole tooth (6) between relative movement distance be no more than the first pole tooth (6) corresponding to the pole shoe (3) Total span.

5. ladder pole flute profile magnetic fluid sealing structure according to claim 1 or 2, it is characterised in that: first pole tooth (6) equidistantly distributed.

6. ladder pole flute profile magnetic fluid sealing structure according to claim 1 or 2, it is characterised in that: in shell (2) inner wall It is socketed with hollow magnetic shield (5), the periphery and magnetic shield (2) inner wall of all pole shoes (3) and axial charging type permanent-magnetic clamp (7) It abuts.

7. ladder pole flute profile magnetic fluid sealing structure according to claim 1, it is characterised in that: the number of the pole shoe (3) Amount is 2~20.

8. ladder pole flute profile magnetic fluid sealing structure according to claim 2, it is characterised in that: the number of the pole shoe (3) Amount is 4~20.

9. ladder pole flute profile magnetic fluid sealing structure according to claim 1 or 2, it is characterised in that: near shell (2) The pole shoe (3) of open end is compressed by end cap (4) and is sealed in shell (2) inner cavity.