CN108869754A - A kind of leakproof magnetic-type magnetic fluid sealing structure - Google Patents

Abstract

The invention discloses an anti-leakage magnetic fluid sealing structure, in which a plurality of ring-shaped pole pieces are arranged at intervals along the axial direction in the space between the outer surface of the shaft and the inner wall of the casing, and a plurality of ring-shaped pole pieces are sandwiched between two adjacent pole pieces. There is an axially magnetized permanent magnet ring, the polarity of the magnetic poles of two adjacent axially magnetized permanent magnet rings is opposite, and a sleeve is set on the shaft between every two adjacent pole pieces , the outer diameter of the shaft sleeve is smaller than the inner diameter of the axially magnetized permanent magnet ring; there is a gap between the end faces of both sides of the shaft sleeve and the adjacent pole shoe end faces, and there is a gap between the inner circular surface of the pole shoe and the outer surface of the shaft. Filled with magnetic fluid. Both axial and radial directions of the invention are sealed, and the sealing pressure resistance capability is enhanced. After changing the leakage path, the length of the path is increased, which can reduce the loss of magnetic fluid and enhance the self-healing ability.

Description

An anti-leakage magnetic fluid sealing structure

technical field

The invention belongs to the field of mechanical engineering seals, and in particular relates to an anti-leakage magnetic fluid seal structure.

Background technique

The existing magnetic fluid sealing structure generally includes a housing with a hollow cavity, a shaft, and a permanent magnet and a pole piece are arranged between the shaft and the housing for magnetic fluid sealing. The defective of prior art mainly shows in the following aspects:

1. The existing sealing gap is generally located in the radial direction, and the seal in the axial direction is realized after being filled with magnetic fluid, and the sealing pressure resistance performance is not good enough.

2. Since the traditional structure only has a radial gap, the flow resistance of the magnetic fluid is small, and the risk of leakage along the axial direction is large. The leakage of the magnetic field in the magnetic fluid seal will lead to a decrease in the magnetic field strength in the magnetic circuit, so that the resistance of the magnetic fluid seal Pressure performance is reduced.

Contents of the invention

In view of the above problems, the present invention aims to provide a magnetic fluid sealing structure capable of improving the pressure resistance of the seal.

The technical solution for solving the problem of the present invention is: a magnetic fluid leakage-proof seal 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 shaft passing through the through hole to the inner cavity of the housing. In the space between the outer surface of the shaft and the inner wall of the housing, a plurality of ring-shaped pole pieces are arranged at intervals along the axial direction, and a pole piece is interposed between two adjacent pole pieces. Axially magnetized permanent magnet rings, the magnetic poles of two adjacent axially magnetized permanent magnet rings have opposite polarities, and a bushing on the shaft is arranged between every two adjacent pole pieces, and the shaft The outer diameter of the sleeve is smaller than the inner diameter of the axially magnetized permanent magnet ring;

There is a gap between the two side end faces of the shaft sleeve and the adjacent pole shoe end faces, and there is a gap between the inner circular surface of the pole shoe and the outer surface of the shaft, and the gap is filled with magnetic fluid.

In the above scheme, axial and radial gaps are constructed by using shaft sleeves, shafts, and pole pieces, and magnetic fluid is injected into the gaps for sealing, so that both axial and radial directions are sealed, and the pressure resistance of the seals is enhanced.

Traditional structures generally only design radial gaps, and can only form a seal in the axial direction. Once the magnetic fluid leaks, it will leak along the axial direction. After adopting the structure of the present invention, if magnetic fluid leakage occurs, the leakage path will first be axial, then radial, then axial, then radial, and finally axial again. Compared with the traditional structure, the length of the leakage path is increased after changing the leakage path, and the increase of the path increases the flow resistance of the magnetic fluid, which can reduce the loss of the magnetic fluid and enhance the self-healing ability.

Further, the shape of the pole shoe closest to the closed end of the housing is the same as that of the pole shoe closest to the open end of the housing. The rectangular cross-section ring is convex downward in the direction of the pole shoe. The rectangular cross-section ring is located on one end face of the pole shoe. A structure with a large gap between the middle of the surface and the axis.

The inner circular surfaces of the two outermost pole pieces are designed to have a structure with a small gap on both sides and a large gap in the middle to facilitate the formation of a magnetic field gradient difference. As we all know, the magnetic field gradient difference is linearly proportional to the pressure resistance of the magnetic fluid seal. , such a structural design can improve the sealing pressure resistance.

The rectangular section ring and the pole piece can be integrally formed.

Furthermore, there are at least three pole pieces. Except for the two pole pieces closest to the closed end and the open end of the casing, the other pole pieces in the middle have the same shape, and the inner circular surface of the pole piece in the middle is V-shaped. , forming a structure with a small gap between the two sides of the inner circular surface and the shaft, and a large gap between the middle of the inner circular surface and the shaft.

The design starting point of the inner circle of the pole piece in the middle is also to create a magnetic field gradient difference to improve the sealing pressure resistance.

Preferably, the number of the pole shoes is 2-10.

The above structure can be used in different forms of demand scenarios, such as reciprocating shaft seals and rotary shaft seals.

When used in a rotary shaft seal structure, the shaft is a stepped shaft; at both ends of the shaft are provided a first bearing and a second bearing abutting against the shoulder of the shaft, the first bearing is close to the closed end of the housing, and the second The bearing is close to the open end of the housing;

The pole piece and the axially magnetized permanent magnet ring are located between the first bearing and the second bearing; a step is provided at the closed end surface of the inner cavity of the housing;

A magnetic isolation ring is provided between the pole shoe closest to the closed end of the housing and one end surface of the first bearing, and the other end surface of the first bearing abuts against the step;

A magnetic isolation ring is provided between the pole shoe closest to the open end of the housing and one end surface of the second bearing, and the other end surface of the second bearing is compressed and sealed in the inner chamber of the housing through the end cover.

When used in a reciprocating shaft seal structure, the axis is the optical axis; a magnetic isolation ring is provided between the pole shoe closest to the closed end of the housing and the inner wall of the closed end of the housing, and the pole shoe closest to the open end of the housing is pressed by the end cover. It is tightly sealed in the inner cavity of the shell to realize reciprocating sealing.

Notable effect of the present invention is:

1. Both the axial and radial directions are sealed, and the pressure resistance of the seal is enhanced.

2. After adopting the structure of the present invention, if magnetic fluid leakage occurs, the leakage path will first be axial, then radial, then axial, then radial, and finally axial. Compared with the traditional structure, the length of the leakage path is increased after changing the leakage path, and the increase of the path increases the flow resistance of the magnetic fluid, which can reduce the loss of the magnetic fluid and enhance the self-healing ability.

3. The inner circular surface of the pole shoe is designed with a structure with small gaps on both sides and a large gap in the middle, which is conducive to the formation of a magnetic field gradient difference and can improve 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 structure of the anti-leakage magnetic fluid seal applied to the rotating shaft.

Fig. 2 is a schematic diagram of Fig. 1 when no ferrofluid is injected (the symmetrical lower half is not shown).

In the figure: 1-shaft, 2-shell, 3-pole shoe, 4-end cover, 5-magnetic isolation ring, 6-shaft sleeve, 7-axial magnetized permanent magnet ring, 8-cone surface, 9 - ring of rectangular section, 11 - first bearing, 12 - second bearing, 13 - step.

Detailed ways

Taking the magnetic fluid seal of a rotating shaft as an example, as shown in Fig. 1-2, a magnetic fluid seal structure with anti-magnetic leakage 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 shaft 1 penetrating from the through hole to the inner cavity of the housing 2 .

In the space between the outer surface of the 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 outer circle of the axially magnetized permanent magnet ring 7 and the pole shoe 3 abuts against the inner wall of the housing 2 . The polarities of the magnetic poles of two adjacent axially magnetized permanent magnet rings 7 are opposite.

A shaft sleeve 6 sleeved on the shaft 1 is arranged between every two adjacent pole pieces 3 . The shaft sleeve 6 is annular. The end surfaces on both sides of the shaft sleeve 6 are planes, and after being installed on the shaft 2, the end surfaces on both sides are vertical surfaces. The outer diameter of the shaft sleeve 6 is smaller than the inner diameter of the axially magnetized permanent magnet ring 7 .

There are at least three pole pieces 3 . The pole shoe 3 closest to the closed end of the housing 2 has the same shape as the pole shoe 3 closest to the open end of the housing 2. Its inner circular surface is a conical surface 8, and on the inner circular surface, a There is a rectangular cross-section ring 9 protruding downward toward the axis 1, the rectangular cross-section ring 9 is located on one end face of the pole shoe 3, and the small-diameter end of the tapered surface 8 is located on the other side end face of the pole shoe 3, forming two inner circular surfaces. The structure has a small gap between the side and the shaft 1, and a large gap between the middle of the inner surface and the shaft 1.

Except for the two pole pieces 3 closest to the closed end and the open end of the housing 2, the other pole pieces 3 in the middle have the same shape, and the inner circle of the pole piece 3 in the middle is V-shaped, forming two sides of the inner circle and two pole pieces. A structure with a small gap between the shaft 1 and a large gap between the center of the inner circular surface and the shaft 1.

There is a gap between the two side end faces of the shaft sleeve 6 and the adjacent end faces of the pole shoe 3, and there is a gap between the inner surface of the pole shoe 3 and the outer surface of the shaft 1, and the gap is filled with magnetic fluid.

The shaft 1 is a stepped shaft. Both ends of the shaft 1 are provided with a first bearing 11 and a second bearing 12 abutting against the shoulder of the shaft 1 , the first bearing 11 is close to the closed end of the housing 2 , and the second bearing 12 is close to the open end of the housing 2 . .

The pole piece 3 and the axially magnetized permanent magnet ring 7 are located between the first bearing 11 and the second bearing 12 . A step 13 is provided at the closed end surface of the inner cavity of the housing 2 .

A magnetic isolation ring 5 is provided between the pole piece 3 closest to the closed end of the housing 2 and one end surface of the first bearing 11 , and the other end surface of the first bearing 11 abuts against the step 13 .

A magnetic isolation ring 5 is provided between the pole shoe 3 closest to the open end of the housing 2 and one end surface of the second bearing 12 , and the other end surface of the second bearing 12 is compressed and sealed in the inner cavity of the housing 2 through the end cover 4 .

Claims (6)

1. a kind of leakproof magnetic-type magnetic fluid sealing structure, including hollow shell（2）, the shell（2）The closed at one end, other end It opens wide, in shell（2）Closed end center be provided with through-hole, further include being worn from through-hole to shell（2）The axis of inner cavity（1）, Axis（1）Outer surface and shell（2）It is axially spaced in space between inner wall to be equipped with multiple cyclic annular pole shoes（3）, two neighboring pole Boots（3）Between be folded with axial charging type permanent-magnetic clamp（7）, two neighboring axial charging type permanent-magnetic clamp（7）Magnetic pole polarity phase Instead, it is characterised in that：In every two adjacent pole shoe（3）Between be provided with and be sleeved on axis（1）On axle sleeve（6）, axle sleeve（6）Outside Diameter is less than axial charging type permanent-magnetic clamp（7）Internal diameter；

The axle sleeve（6）Both sides of the face pole shoe adjacent thereto（3）There are gap, pole shoes between end face（3）Inner headed face and axis （1）There are gap between outer surface, gap location is marked with magnetic fluid.

2. leakproof magnetic-type magnetic fluid sealing structure according to claim 1, it is characterised in that：Near shell（2）Closing The pole shoe at end（3）With near shell（2）The pole shoe of open end（3）Shape is identical, and inner headed face is the conical surface（8）, and in inner circle On face, it is located at the conical surface（8）Major diameter end side be equipped with towards axis（1）The downwardly convex rectangle cross-section ring in direction（9）, the rectangle cross-section ring （9）Positioned at pole shoe（3）A side end face, the conical surface（8）Miner diameter end be located at pole shoe（3）Another side end face, formed inner headed face two Side and axis（1）Gap is small, among inner headed face and axis（1）The big structure in gap.

3. leakproof magnetic-type magnetic fluid sealing structure according to claim 2, it is characterised in that：The pole shoe（3）At least Three, except near shell（2）Two pole shoes of closed end and open end（3）Outside, other to be located in the middle pole shoe（3）Shape phase Together, and it is located in the middle pole shoe（3）Inner headed face be V-shaped, form inner headed face two sides and axis（1）Gap is small, in inner headed face Between and axis（1）The big structure in gap.

4. leakproof magnetic-type magnetic fluid sealing structure according to claim 1 or 3, it is characterised in that：The pole shoe（3）Number Amount is 2~10.

5. leakproof magnetic-type magnetic fluid sealing structure according to claim 1-4, it is characterised in that：The axis（1） For multi-diameter shaft；In axis（1）Both ends be equipped with and axis（1）Shoulder abut first bearing（11）And second bearing（12）, first Bearing（11）Close to shell（2）Closed end, second bearing（12）Close to shell（2）Open end；

The pole shoe（3）With axial charging type permanent-magnetic clamp（7）Positioned at first bearing（11）And second bearing（12）Between；In shell （2）Step is equipped at the closed end of inner cavity（13）；

Near shell（2）The pole shoe of closed end（3）With first bearing（11）Magnetism-isolating loop is equipped between one end face（5）, first axle It holds（11）Other end and step（13）It abuts；

Near shell（2）The pole shoe of open end（3）With second bearing（12）Magnetism-isolating loop is equipped between one end face（5）, the second axis It holds（12）Other end passes through end cap（4）Compression is sealed in shell（2）Inner cavity.

6. leakproof magnetic-type magnetic fluid sealing structure according to claim 1-4, it is characterised in that：The axis（1） For optical axis；Near shell（2）The pole shoe of closed end（3）With shell（2）Magnetism-isolating loop is equipped between the inner wall of closed end, near shell Body（2）The pole shoe of open end（3）Shell is sealed in by end cap compression（2）Reciprocating seal is realized in inner cavity.