RU2546377C1 - Magnetic fluid seal of non-magnetic shaft ps-40 - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention is referred to sealing equipment and can be used in machine building industry for sealing of non-magnetic shafts. A magnetic fluid seal of a non-magnetic shaft comprises magnetic fluid and a magnetic system made from a permanent magnet and a magnetically conductive bush fitted with annular grooves and embracing the shaft with a gap, the bush ends are provided with projections adjoining the opposite magnet poles, the annular grooves are made on the outer cylindrical surface of the magnetically conductive bush and are of triangular cross-section, a non-magnetic spacer is set between the bush and the permanent magnet, and the groove are filled by diamagnetic material.

EFFECT: improved manufacturability and increased retaining ability of the seal.

2 cl, 1 dwg

Description

The invention relates to a sealing technique and can be used in mechanical engineering for sealing non-magnetic shafts.

Known magneto-fluid sealing of a non-magnetic shaft (Fertman VE Magnetic fluids - natural convection and heat and mass transfer. Mn .: "Science and technology", 1978, p.55, fig.21.b), containing an annular permanent magnet, magnetic poles, which concentrate the magnetic field in the annular volume between the magnetic poles adjacent to the non-magnetic shaft.

Its disadvantage is the low holding capacity. This is due to the fact that the seal allows you to create one magneto-liquid ring with a low holding capacity.

Known magnetic fluid seal of a non-magnetic shaft (RF patent No. 2407936 C2, IPC F16J 15/53, 2010), adopted as a prototype containing a magnetic sealing system made in the form of a sleeve of magnetically conductive material covering the shaft with a gap on the surface of the sleeve facing the shaft, annular grooves are made, which are filled with diamagnetic material, and protrusions adjacent to the opposite poles of the magnet are located on the edges of the outer surface of the sleeve.

The disadvantages of the seal are the complexity of manufacturing a sleeve with annular grooves in the form of a dovetail on the inner surface facing the shaft, and the low holding capacity of the seal. The complexity of the manufacture is due to the difficulty of making the dovetail grooves on the inner surface of the sleeve, while the gap between the tips of the hubs should be less than 1 mm. The low holding capacity is the result of a not very successful formation of a magnetic field in the zone of location of the magneto-liquid plug.

The technical result achieved by the invention is to increase the manufacturability of manufacturing and to increase the holding capacity of the seal.

The technical result is achieved by the fact that in the magneto-liquid seal of a non-magnetic shaft containing magnetic fluid and a magnetic system made of a permanent magnet and a sleeve of magnetically conductive material with annular grooves covering the shaft with a gap, protrusions are located at the ends of the sleeve adjacent to opposite magnet poles, ring the grooves are located on the outer cylindrical surface of the magnetically conducting sleeve and have a triangular cross section, while between the sleeve and the permanent magnet azmeschena nonmagnetic spacer, and the grooves are filled with diamagnetic material.

The drawing shows the design of the magnetic fluid seal of a non-magnetic shaft. The sleeve 1, made of a magnetically conductive material (St.3 ÷ St.10), covers a non-magnetic shaft 2 with a gap 3. On the outer cylindrical surface of the sleeve 1, annular grooves are made 4. The thickness of the sleeve between the bottom of the annular groove and the inner surface of the sleeve is small and may make up tenths of a millimeter. The grooves 4 are filled with diamagnetic material. At the ends of the sleeve there are protrusions 5, which are adjacent to the opposite poles of the permanent magnet 6. Between the permanent magnet 6 and the sleeve there is a non-magnetic spacer 7. A magnetic fluid 8 is introduced into the gap between the sleeve 1 and the shaft 2, which forms hermetic rings under the influence of the magnetic field.

Sealing works as follows. The permanent magnet 6 in the seal serves as a source of magnetic field. The magnetic flux created by him leaves the north pole, passes through the protrusion 5 of the sleeve 1 adjacent to it, passes through the sleeve 1, and closes to the south pole of the magnet through the opposite protrusion 5. The cross section of the sleeve 1 in the region of the grooves 4 is small, so the material of the sleeve 1 here enters a saturation state, which displaces the magnetic flux into the working gap 2. Due to this, an increased magnetic field is created in the working gap opposite the grooves 4. Grooves 4 with a triangular cross-section provide the greatest maximum magnetic field strength in the working gap. Magnetic fluid 8 is drawn into these zones with maximum magnetic field strength and forms hermetic rings that overlap the gap 3 and prevent the passage of the medium to be sealed through it. Each magneto-liquid ring is capable of perceiving a pressure differential, depending on the field strength in the gap and the magnetic properties of the magnetic fluid. The pressure differential held by the seal is determined by the sum of the pressure drops of all the magneto-liquid rings in the gap.

The design of this seal is simple and manufacturable. The implementation of the grooves 4 with a triangular cross-sectional shape on the outer cylindrical surface of the sleeve 1 is simpler and more technologically advanced than the implementation of the grooves on the inner surface of the sleeve in the form of a dovetail. Grooves 4 may not be filled with diamagnetic material. But filling the grooves with diamagnetic material reduces the magnetic flux that closes between the walls of the groove, increasing the field strength in the gap being sealed, and therefore the holding capacity of the seal. The use of a diamagnetic material with elastic mechanical properties increases the mechanical rigidity and strength of the sleeve 1, which increases the manufacturability of the assembly and simplifies the maintenance of the seal. A spacer 7 of non-magnetic material provides additional rigidity to the sleeve 1, increasing the manufacturability of the assembly and bulkhead seals, as well as the reliability of the seal.

The implementation of the sleeve 1 with annular grooves on the outer cylindrical surface allows you to more effectively generate a magnetic field in the working clearance of the seal and increase its maximum holding capacity. Numerical simulation of the magnetic field of the magnetic system of the proposed seal showed that it allows to increase the maximum retained differential pressure by 1.8 ÷ 2.1 times compared with the prototype when using the same magnet.

Thus, the present invention improves the manufacturability of the manufacture of the seal and its maximum retentive differential pressure.

Claims (2)

1. Magneto-liquid seal of a non-magnetic shaft containing a magnetic fluid and a magnetic system made of a permanent magnet and a sleeve of magnetically conductive material with annular grooves covering the shaft with a gap, and protrusions adjacent to opposite poles of the magnet are located at the ends of the sleeve, characterized in that the ring the grooves are located on the outer cylindrical surface of the magnetically conductive sleeve and have a triangular cross section, and a nonmagnetic gap is placed between the sleeve and the permanent magnet avka. 2. The magneto-liquid seal of the non-magnetic shaft according to claim 1, characterized in that the grooves are filled with diamagnetic material.