RU2286496C2 - Method of charging magneto-fluid shaft seal - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: method comprises supplying magnetic liquid to the space under the even or uneven teeth, moving the shaft or seal in the axial direction keeping the output of the charging openings between teeth on the opposite side with respect to the line of symmetry of the magnetic field, and setting the shaft or seal into the initial position.

EFFECT: enhanced reliability.

2 dwg

Description

The invention relates to mechanical engineering and is intended for refueling magneto-liquid seals.

A known method of filling the gaps of magneto-liquid seals with magnetic fluid, implemented in / 1 / by squeezing it from elastic chambers located in the grooves of the pole pieces, through channels into the gap during assembly of the seal.

The disadvantage of this method is the complexity and inability to refuel multi-pole pole consoles.

There is a method of filling magnetic fluid seals with magnetic fluid, implemented in / 2 /, where the magnetic fluid is supplied to the intermediate cavities under the magnets using a switchgear located in the shaft cavity, through the channel and holes.

The disadvantages of this method are: complexity, unreliability, the inability to refuel with multi-prong poles. The difficulty lies in the need for consistent accurate alignment of each filling hole with the filling channel of the switchgear during the filling process. The unreliability is due to the fact that all the filling holes exit into the cavity of the shaft, and insufficient tightness of the switchgear will lead to the bypass of all stages of the seal, and therefore, the depressurization of the seal. The impossibility of refueling the multi-prong poles is explained by the fact that the liquid introduced into the cavity under the magnets does not penetrate further than the second tooth due to the formation of closed cavities in the interdental space.

The technical result achieved by the invention consists in high-quality refueling of the seal with multi-tooth poles, where the quality of refueling is understood as refueling of each tooth with the required volume of magnetic fluid without disassembling the seal at any demanded time, in simplification of the technology of refueling.

The result is achieved by introducing magnetic fluid through the filling holes in the shaft under even or odd teeth, moving the shaft or seal in the axial direction so that the outputs of the filling holes in the shaft are on the opposite side from the line of symmetry of the magnetic field between the teeth, then magnetic fluid is introduced under odd or even teeth, after which the shaft or seal can be returned to its original position.

Figure 1 shows a General view of the seal that implements this method, figure 2 is a graphical representation of the distribution of magnetic field strength in the gap on the shaft surface and the location of the outlets of the filling holes in relation to the distribution of tension.

A permanent magnet 2 is installed in the housing 1 with adjacent pole attachments 3, with teeth 5 facing the shaft 4. Each gap between the tooth and the shaft is filled with magnetic fluid 6. There are filling channels in the shaft 7. There is one filling for each pair of adjacent teeth channel. The channels are evenly spaced around the circumference of the shaft. The channel outputs are located under the teeth and are offset from the lines of symmetry of the magnetic field between the teeth in one direction - the side of the even or odd teeth. Each channel is equipped with a sealed plug 8.

Sealing works as follows. The permanent magnet 2 in the seal serves as a source of magnetic field. The magnetic flux created by it is supplied by the pole attachments 3 to the gap with the shaft 4. The teeth of the pole arms 5 redistribute the magnetic flux in the gap, and the magnetic field becomes sharply inhomogeneous. Magnetic fluid 6 is drawn in the area with maximum tension and forms a sealed plug with increased internal pressure. Magnetic fluid under the teeth is introduced through the filling channels 7. Initially, for example, all the even teeth are filled, then the shaft moves along its axis so that the outputs of the filling holes are on the opposite side from the line of symmetry of the magnetic field between the teeth and the odd teeth are filled through the same channels . After refueling, each channel is hermetically sealed with a technological plug 8. Depending on the design of the magneto-liquid seal, the shaft may remain in its last position or return to its original point. In the proposed method, it is allowed to move the magneto-liquid seal relative to the shaft, it is only important that when moving the seal the outputs of the filling holes are on the opposite side from the line of symmetry of the magnetic field between the teeth.

Each magneto-liquid plug is capable of perceiving a pressure drop, which is determined by the formula:

where μ ₀ is the magnetic constant,

M is the magnetization of the magnetic fluid,

N is the magnetic field in the gap on the surface of the shaft,

H _max and H _min - the maximum and minimum magnetic field strengths at the boundaries of the magnetofluidic plug at the moment it holds the maximum pressure drop.

The pressure drop held by the seal is determined by the sum of the drops of all the magneto-liquid plugs under the teeth.

Under the multi-pronged pole there is a wave-like distribution of the magnetic field, alternating maxima and minima of tension. Lines AB - lines of maximum magnetic field strength under the teeth. The CD lines are the lines of minimum magnetic field strength under the teeth, they can be arbitrarily called the lines of symmetry of the magnetic field separating the magnetic fields of two adjacent teeth. When shifting from each CD line at least to the right, at least to the left, the field strength will increase.

Place a drop of magnetic fluid in the gap between the first and second prong (Figure 2). If the drop is to the right of the line of symmetry CD, then the magnetic field forces will draw it into the gap under the second tooth, if the drop is to the left of the line of symmetry CD, then the magnetic field forces will draw it into the gap under the first tooth. If the outlet of the filling channel extends onto the CD line, then the magnetic fluid to be charged can fall under both the first and second teeth. What part of the volume of injected magnetic fluid will be under the first, and which under the second prong depends on chance, for example, on the speed of fluid supply.

In the proposed seal, each pair of teeth is equipped with one filling channel. The outlet of each filling channel is located in the interdental zone and is offset from the line of minimum magnetic field strength on the shaft surface towards even teeth. This arrangement of the channel exits ensures that when filling, the entire magnetic fluid introduced through the channel is drawn in under one even tooth. Sequentially bypassing the channels, dress even the teeth. Then the shaft is moved along its axis relative to the magneto-liquid seal. Moreover, if initially the output of each filling channel was shifted from the line of minimum magnetic field strength on the shaft surface to the side of even teeth, then after moving the shaft it shifted from the line of minimum magnetic field strength to odd teeth. Again, sequentially bypassing the channels, the odd teeth are already filled.

These features allow for controlled refueling of each seal tooth with multi-tooth pole attachments.

Thus, the proposed method allows for each tooth of the pole to sequentially enter the required volume of magnetic fluid, to provide increased reliability of the seal, to create the ability to refuel and refuel the seal at any desired time, simplifies the technology of operation of the seal.

Information sources

1. Auth. St. USSR No. 779697, MKI 2 F 16 J 15/40.

2. Auth. St. USSR No. 723281, MKI 2 F 16 J 15/40.

Claims (1)

A method of refueling a multi-prong magneto-liquid shaft seal, which consists in introducing magnetic fluid under the tooth through the filling holes in the shaft, characterized in that the magnetic fluid is introduced under the even or odd teeth, moving the shaft or seal in the axial direction so that the outlets of the filling holes in the shaft are on opposite the line of symmetry of the magnetic field between the teeth, then introduce magnetic fluid under the odd or even teeth, after which the shaft or seal can be returned to and original position.

Images