SU1323814A1 - Shaft magnetic-fluid seal - Google Patents

Abstract

The invention relates to a sealing technique and can be used to seal shafts operating under pressure drop conditions. The aim of the invention is to increase the reliability of compaction by changing the magnetic induction in the working gap depending on the speed of rotation of the shaft. The magnetic-liquid seal is equipped with additional pole attachments 4, opposite which on the shaft 5 a sleeve 8 is installed, made of a non-magnetic electrically conductive material. When the shaft 5 rotates in the sleeve 8, eddy currents are induced, which create their own magnetic flux directed oppositely to the magnetic flux Q ,, si. As the rotational speed of the shaft 5 increases, more of the flow is not transmitted by the sleeve 8, increasing the value of the working flow holding the magnetic fluid in the working gap 6. The presence of an annular projection 10, which also induces eddy currents, causes a significant part of the magnetic flux of the magnet 2 close through the working gap 6. 1 Cp f-crystals. 1 il. with to GO 00 7 8

Description

The invention relates to a sealing technique that can be used to seal shafts operating under pressure drop conditions.

The purpose of the invention is to increase the reliability of compaction by changing the magnetic induction in the working gap depending on the speed of rotation of the shaft.

The drawing shows a magnetic-fluid shaft seal, a slit.

The magnetic-liquid shaft seal comprises a housing 1 in which an annular permanent magnet 2 is installed with the main 3 and an additional 4 pole attachment. The main pole attachments 3 form with a sealed shaft 5 a working gap b filled with magnetic fluid. On the surface of the shaft 5 formed to the main pole attachments 3, annular grooves 7 are made, filled with diamagnetic material. On the shaft 5 opposite the additional pole lugs there is a sleeve 8, made of non-electrically electrically active material and insulated from the shaft with heat insulating material 9. The sleeve 8 can be made with an annular protrusion 0, which is placed between the additional attachments 4.

The magneto-fluidic shaft seal works as follows.

If the shaft 5 is not rotated, then the magnet-Hfjui flux of the scattered ring magnet 2 closes through the ferromagnetic shaft 5, droning the electrically conductive sleeve 8. At this time, the sleeve 8 has no effect on the passage of the magnetnog Q flow, bi dissipated nor oi; has a maximum value, providing a minimum gradient of the magnetic magnitude of the working gap 6.

When the shaft 5 rotates, the bushing 8 induces the heating currents, which create their magnet the 1st flow, directed oppositely to the magnetic core C ,,; i 2. Sleeve 8 in this case acts as a screen for the magnetic flux Qusi scattering. As the rotational speed of the shaft 5 increases, an ever larger part of the flow i is not passed by the sleeve 8, increasing the magnitude of the working magnetic flux Qnp (since the total magnetic flux of the magnet 2 remains unchanged). This automatically regulates the magnetic flux holding the magnetic fluid in the working gap 6, depending on the number of revolutions of the shaft, which increases the reliability of the seal.

Editor L. Rechka Order 295) / 42

Compiled by A. Beltsov

Tehred I. VereEcorrector M. De.mchik

Circulation 81 IP subscription

(.i: i) eTKi, iiiiGro Committee of ToS (P on .ae.uiM of inventions and discoveries

I ZOZG). Moscow, F - 35, Raupkkg. nab. d. 4/3 1 p {; i-1v0; itpei | 1o-hk) ligraphic (; 1st enterprise, Uzhgorod, Proektna st., 4

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At low speeds of the Brai. 1 shaft, it is possible to assume the absence of a second QnS2 flux scatters and assume that the entire magnetic flux scatters through the shaft, piercing the sleeve 8. To maintain this assumption when the speed of the shaft 5 increases, The screening of its action of the sleeve 8 increases the flow of Qns2, and a protrusion 10 located between the additional pole attachments 4 is made on the sleeve 8.

The protrusion 10 prevents that part of the magnetic flux of the scattering, which, with an increase in the number of revolutions of the shaft 5 due to the shielding effect of the sleeve 8, should slide along it, not passing through the shaft, and therefore not penetrating the sleeve 8. The presence of the protrusion 10, in which eddy currents are also induced, cause a significant portion of the magnetic flux to close through the working gap b.

The necessary relationship between the magnitudes of the magnetic fluxes and in the absence of shaft rotation can be achieved both by choosing the magnetic permeabilities of the fluid of the main and additional pole attachments, their dimensions, and by forming a special air gap in the path of the workflow Q, ip.

Claims (2)

1.Magnetic-liquid shaft seal, contains an annular magnet installed in the housing with pole attachments, encompassing them, a sealed shaft with annular grooves made opposite pole attachments and filled with a diamagnetic material, and a magnetic fluid in the working gaps, characterized in that increasing the sealing reliability by changing the magnetic induction in the working gap depending on the shaft speed, it is equipped with a sleeve of non-magnetic electrically conductive material and at least two additional body pole attachments placed between the existing pole attachments and the magnet, while the sleeve is installed under the additional pole attachments in the shaft. 2. Shaft sealing according to claim 1, characterized in that the sleeve is made with an annular protrusion that is placed between the additional pole attachments.