SU1737202A2 - Magnetic-liquid seal - Google Patents

Abstract

Use: for sealing rotating shafts when transferring motion to gaseous or liquid media. The invention: a sleeve of non-magnetic material mounted on the shaft. The magnetic assembly is made in the form of two permanent magnets with external and internal pole tips. Between the outer lugs mounted cage of non-magnetic material. The face seal gaps are formed by external tips and a magnetic conductor, radial gaps - by a sleeve and internal tips. 1 il.

Description

The invention relates to a sealing technique and can be used in all sectors of the national economy to seal the rotating shafts when transmitting motion to gaseous or liquid media and is additional to the main author. St. No. 813060.

The purpose of the invention is to increase the reliability of seals.

The drawing shows the seal, cut.

The seal includes a magnet assembly in the form of permanent magnets 1 and 2 with pole pieces 3, 4 and 5, 6, a sleeve 7 made of magnetic material mounted on the shaft 8 and matched in diameter with the inner pole pieces 4, 5 of the magnet assembly, the magnetic circuit 9 grasping the end surfaces of the outer pole tips 3 and 6 of the magnet assembly and the ferromagnetic fluid 10 in sealing gaps 5i, 62, 5z, 6c.

To reduce friction losses, eliminate sticking of pole pieces 3 and 6 on magnetic core 9, as well as providing the required length of working clearances bz and 64, the liners 11, 12 of antifriction material, such as babbit, are placed on said pole pieces, and the magnetic assembly is mounted in the clip 13 from non-magnetic material.

To create an uneven magnetic field in the sealing gaps 5i, 62, 5z, 5z on the cylindrical surfaces of the pole pieces 4 and 5, annular grooves are made on the side of the sleeve 7, as well as on the end surfaces of the pole pieces 3 and 6.

Permanent magnets 1 and 2 with pole pieces 3. 4 and 5, 6, magnetic core 9, sleeve 7 and ferromagnetic fluid 10 in sealing gaps 5i. 62, of, & 4 form a closed magnetic circuit corresponding to flux F in the drawing.

With the passage of the magnetic flux F through the working gaps From and & 2, a radial force arises, under the action of which the pole tips 4 and 5 stick to

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sleeve 7, choose the gaps di and bg in one direction.

With the passage of the flow F, an axial force also arises, under the influence of which the magnetic assembly in the cage 13. is attracted to one of the end surfaces of the electric conductor 9 with a force

Q 4.06 S (Bi2-B22), (1)

where S is the cross-sectional area of the pole pieces 3 and 6 in the gap area (5z and 64;

W and B2 - induction of the magnetic field in the gaps 5z and dz, respectively.

Friction losses in the bearing assembly, the liner 11 (12) of the magnetic core 9 is

M f (Q + P) R, (2)

where f is the friction coefficient of the slip pair of the material of the liner 11 (12) is steel (the material of the magnetic circuit 9);

P is the force of pressure drop held by the seal, which presses the magnetic assembly in the cage 13 against the end surface of the magnetic circuit;

R - the average radius of the liner 11.

Due to the non-uniform distribution of the magnetic field in the gaps 5z and dz, because of the grooves on the pole pieces 3 and 6, the ferromagnetic fluid 10 always tends to penetrate into the zone of contact of the liner 11 (12) with the magnetic circuit 9, filling all the micro gaps between them. Therefore, in the seal on the side of the gaps 5z and H4 there is a semi-liquid friction mode, since the ferromagnetic fluid, besides the sealing designation, also plays the role of a lubricant. The slip friction coefficient f of the steel-babbit pair in semi-liquid friction mode approaches the rolling friction coefficient, It is less than 0.01-0.025.

The magnetic force resulting from the interaction of the ferromagnetic fluid with the field of the permanent magnets 1 and 2 prevents leakage under the action of pressure drop from the gaps 5i, 62, 63. dz. The magnitude of this force depends on the magnetic

characteristics of ferromagnetic fluid, induction in the gaps 5i, 62, dz, dz and is proportional to the magnetic field gradient in the specified gaps.

On gaps dz and 64 between magnetic

node in the holder 13 and the magnetic core 9 made a movable connection, transmitting the rotational movement of the shaft 8, as well as its radial beating.

The gaps d- and 5a also made a movable joint transmitting axial and angular displacements of the shaft being compressed,

The shear force required for axial and angular displacement of the sleeve 7 with the shaft 8 relative to pole pieces 4 and 5 can be determined from the expression

F 2f 1 PM, (3)

where fi is the coefficient of friction slip

steel on steel pairs (material of pole pieces 4, 5 and bushings 7) when lubricating contacting surfaces with ferromagnetic liquid 10;

PM is one-sided magnetic power

the attraction of the sleeve 7 to one of the pole pieces 4 or 5.

The seal is a structurally completed unit. It is assembled separately from the shaft 8.

Claims (1)

separately regulated, subjected to running and control tests, which allows to increase the reliability of the seal. Invention: Fluid seal on auto St. No. 813060, characterized in that, in order to increase the reliability of the seal, it is provided with a sleeve of magnetic material mounted on the shaft, the magnetic assembly is made in the form of two constant magnets with outer and inner pole lugs, between the latter there is a cage of non-magnetic material, and the face seal gaps are formed by the outer pole lugs of the magnet assembly and the magnetic core, the radial gaps are by the sleeve and the inner pole lugs U