RU1820114C - Magnetic liquid seal - Google Patents

Abstract

Use: for sealing. rotating shafts 0 SUMMARY OF THE INVENTION: The shaft enters the housing, in which a magnetic unit is installed. "The sealing gaps are filled with magnetic fluid. The magnetic assembly is made in the form of a package of 1-2 mm thick ring permanent magnets mounted along the shaft axis and the end surfaces of two ring pole attachments 0.2 - 0.3 mm thick covering them. Between them are installed dividing centering elements of non-magnetic antifriction material. The edges of the pole attachments are bent towards each other with the formation of a gap between them and the shaft within 0.2-0.3 mm, “1 zpp-fla, 2 silt.

Description

The invention relates to a sealing technique and may find application for magnetic and non-magnetic .- rotating shafts, centrifugal pumps, compressors.

A magnetically liquid sealing device (MF) of a rotating shaft is known, including an annular permanent magnet with adjacent pole attachments, on which protrusions are made, located in the cavity under the permanent magnet and directed towards each other (ed. St. G, class F 16 J 75/40, 1983).

Washers with non-magnetic gaskets are placed between the shaft and the pole attachments. On the outer surface of the magnetically conducting washers, protrusions are made, the protrusions of adjacent washers adjacent to the conical protrusions of the pole attachments of opposite polarity. Part of the magnetic flux passes through the shaft, so increasing the number of washers does not saturate the shaft steel.

A disadvantage of the known device is the limitation of the sealing ability of the seal due to the loss of magnetic flux for dispersion, the technological difficulties in manufacturing pole attachments, washers for small diameters of the MF.

It is also known that the rotary shaft MFD (auth. St. N 1099160, class F 16 J 15LO, 1983), including magnets, pole attachments in the form of packets of mesh elements mounted rigidly and tightly on a rotating shaft. The cavity formed between the case of the mechanism and the set of magnets and pole attachments is filled with magnetic fluid00 N) O

bone (MF) "The disadvantages of the described device include the limitation of the sealing ability of the seal due to the impossibility of concentrating the magnetic flux on the pole attachments, mechanical wear of the mesh packages while rotating the shaft"

As a prototype, an MFL of a rotating shaft was adopted (ed. St. No. 811027, class F 16 J 15LO, 1Я78), consisting of a housing, a sealed shaft, included in the casing of the magnetic circuit, concentrically arranged relative to the shaft of the outer and inner rings of permanent magnets separated by a cylinder made of a magnet of soft material, which, being installed in the form of a set of rings with a separating sealing non-magnetic gasket, form along the axis of the shaft with an opposite arrangement of the poles of the permanent magnets in the axial direction mknuty of magnetic flux that ensures sealing when filling MF gap in reciprocating and rotational motion of the shaft.

The disadvantages of the prototype include the design complexity associated with the need to seal two types of movement at the same time, a specific area of application and operating conditions, R in particular, the seal is designed for low speeds of rotation of the shaft, has significantly cleanly sealed contact surfaces, which reduces the reliability of the seal. The installation of magnets of opposite polarity creates an almost uniform closed magnetic flux in the axial direction, the efficiency of which is reduced due to separation fluoroplastic gaskets. There are no magnetic flux concentrators in the seal. A set of rings and gaskets do not represent an independent element of the sealing assembly, which excludes the regulation of magnetic flux due to a change in their number. PTFE gaskets do not provide sufficient centering accuracy for the shaft, and

That is, the clearance value, which is essential for the kept differential pressure. The seal cannot be used for non-magnetic shafts.

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The purpose of the invention is to increase the operational reliability of the MFM of magnetic and non-magnetic shafts by delimiting and maximizing the use of magnetic fluxes of sequentially mounted magnets and pole attachments, their concentric location relative to the shaft due to the design of pole attachments and the presence of dividing centering elements.

The goal is achieved in that, to increase the reliability of the design, it is a set of packages of elementary MFLs, consisting of ring permanent magnets 1-2 mm thick and two ring pole attachments 0.2-0.3 mm thick, the packages are separated from each other other dividing centering elements made of non-magnetic antifriction material. For a non-magnetic shaft, the edges of the attachments bend towards each other so that the gap between them and the shaft is in the range 0.2-0.3 mm. For this purpose, a set of elementary M1U packages is rigidly and hermetically installed in the mechanism case, between which separation elements (gaskets) of non-magnetic antifriction material are placed, which you have with you. and centering supports for the shaft. Packets are stacked with the same poles to each other. The separation of the packets by non-magnetic gaskets allows one to minimize the loss of magnetic flux due to dispersion, to prevent mixing of the liquid being compacted and the magnetic fluid during the operation of the MNA, and the set of packets can compensate for the given pressure drop.

1, - L of the magnetic drive shaft, each installed package consists of an axially magnetized permanent magnet 1-2 mm thick with magnetically conductive pole attachments adjacent to its ends with a thickness of 0.2-0.3 mm, which corresponds to optimal values blunt edges of the adopted tooth profiles of pole attachments

In addition, the selected thickness of the prefixes ensures the passage of a magnetic flux of a permanent magnet of selected sizes with minimal losses. Between the cavity between

The 51 parts of the bag and the shaft are filled with magnetic fluid.

2; For magnetic shafts, adjacent to the permanent magnet pole attachments are bent along the inner diameter towards each other to create a working gap between themselves and the shaft within 0.2-0.3 mm, which is the most optimal seal operation, working gap filled with magnetic fluid.

In FIG. 1 shows the proposed seal design; figure 2 - packages of elementary MFU (a - for a magnetic shaft, b - for non-magnetic)

A magneto-liquid seal consists of a housing 1, a shaft 2, pressed inside the housing 1 of a sleeve 3. Of a cylindrical shape made of non-magnetic material with profile slots around the perimeter of a cylindrical surface. Inside the sleeve 3, packages of elementary FFMs are installed, consisting of pole attachments of M permanent magnets 5. The packages are separated from each other by non-magnetic anti-friction separating elements 6. The set of FFM packages are rigidly and hermetically fastened to the housing with a pressure cap 7 screws 8 “Channels 9 and 10 in the upper and lower part of the housing 1 are used for supplying and discharging coolant.

The shaft T is hollow for accommodating an automatic metering device for sealing magnetic fluid 11. The automatic metering device consists of a filling tube 12, a piston 13 spring-loaded with a spring 14.

The magnetic fluid 11 for replenishment of the MFL enters through channel 15. The edges of the pole attachments 4 for the magnetic shaft are made straight {Fig. 2a), for non-magnetic shafts - bent towards each other (Fig. 26).

Sealing works as follows. The magnetic flux of the permanent magnet 5 of each elementary MFU package is closed through the pole attachments 4, the working gaps between the attachments 4 and the shaft 2 ,. which is filled with liquid 11.

Packets of elementary MFLs drawn by poles of the same name to each other exclude dispersion of the magnetic flux and create anti-friction

non-magnetic gaskets 6 zero magnetic field strength, which makes it possible to increase the retention pressure drop of each packet.

The antifriction distinguishing elements 5 center the packages relative to the shaft 2 and provide a constant working gap between the pole attachments C. and the shaft 2. The packages of elementary MFU are inserted into the sleeves 3, which is hermetically installed in the housing 1 and having a recess in the middle part for the passage of cooling water entering and outlet along channels 9 and 10 “The sleeve 3 is pressed by the pressure cap 7 using screws 8”

When refueling the working gap, the MF fills the internal volume of the refueling device (charger) through the tube 12, through which the channel 15 enters the working gaps between the pole attachments 4 and the shaft 2 and antifriction plugs 5 °

Magnetic fluid is pressed into the internal volume of the memory by a spring-loaded piston 13. When pressure pulsates, the MF is partially squeezed out into the volume of the memory and the piston 13f- moves, which compresses spring I. When the MF pressure is equalized

The working gap is replenished by moving the spring-loaded piston 13 "

Compared with the prototype of the present invention allows:

- increase the retained working pressure with the same dimensions 2 - 2.5 times,

- increase the operational reliability of the MFU,

- reduce the complexity of manufacturing and installation by 1.5-2.0 times;

- expand the scope of use of MF and non-magnetic shafts,

- reduce operating costs by about 20-30%.

Claims (2)

1. A magneto-liquid seal comprising a sealable shaft entering a housing, a magnetic assembly installed in the housing, and magnetic fluid in the sealing gaps, which can be removed so that the magnetic assembly is designed as a package of 1-2 mm thick ring permanent magnets installed along the shaft axis and covering their end surfaces of two annular pole attachments with a thickness of 0.2-0.3 mm and installed between them separating centering elements made of non-magnetic antifriction material. 2. The seal according to claim 1, with the fact that the edges of the pole attachments are bent towards each other with the formation of a gap between them and the shaft, which is in the range of 0.2-0.3 mm . . / J and 5 /5 te.2