JPH06327228A - Shaft sealing apparatus - Google Patents

Abstract

PURPOSE:To obtain a shaft sealing apparatus having high reliability for shaft sealing by providing a small gap between the external circumference of poles and a housing to form a magnetic field which is equilibrium to the internal circumferential portion in view of sealing a shaft by leaving a magnetic fluid. CONSTITUTION:A magnetic fluid 7 is left, with formation of magnetic field due to an electromagnet 6, at a small gap delta provided between the internal circumference of poles 9, 10 and a rotating shaft 1 and the poles 9, 10 are formed to provide a small gap epsilon against a housing 11 by applying such magnetic fluid to a shaft sealing mechanism which is supported by a rubber ring 8 provided against the internal circumferential surface of the housing 11 supported through a bearing 4. Simultaneously, a magnetic field which is equilibrium to the internal circumferential portion of the poles 9, 10 is formed against a weak magnetic material housing 11 to leave the magnetic fluid 7 in view of sealing the shaft with the internal and external circumferences of the poles 9, 10. Thereby, highly reliable shaft sealing apparatus can be obtained by sealing the shaft with magnetic fluid which can alleviate vacuum transmissivity of the rubber ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing device which seals a vacuum or gas by using a magnetic fluid around a rotary shaft of a rotary machine.

[0002]

2. Description of the Related Art Magnetic fluids are widely used in shaft sealing devices for vacuum or gas sealing, which are used for shaft sealing regardless of static field and rotating field, and are formed by forming a magnetic field in a minute gap. The mechanism is being miniaturized, simplified, and further improved in reliability, and is being actively developed.

FIG. 10 shows an example of a conventional shaft sealing device used in a rotary machine. Reference numeral 1 is a rotating shaft, and a pair of magnetic poles 2 and 3 spaced along this axial direction are supported by the bearing 4 and the housing 5 so as to maintain a minute gap δ around the rotating shaft 1, and the magnetic pole 2 , 3 are provided with a plurality of magnets 6 in the circumferential direction, and a magnetic fluid 7 is interposed in the minute gap δ. That is, by the magnet 6, the one magnetic pole 2 is rotated to the rotary shaft 1
Then, a magnetic field that forms a circuit flowing to the other magnetic pole 3 is formed to form a magnetic field in the gap δ between the magnetic poles 2 and 3 and the rotating shaft 1, and the magnetic fluid is retained to bring the magnetic fluid into non-contact for shaft sealing.

[0004]

SUMMARY OF THE INVENTION In an apparatus for sealing a shaft in a non-rotating manner by using a magnetic fluid, the magnetic pole and the rotating shaft can be formed depending on various conditions such as formation of a characteristic magnetic field of the magnetic fluid itself and rotating peripheral speed. The proper gap value between the two is determined and the shaft seal is constructed. However, in the conventional shaft seal device shown in FIG.
3 is supported by a housing 5 placed on the outer peripheral side thereof, a bearing 4 and a rubber ring 8 and is sealed by a shaft.

In this shaft seal, if the rubber ring 8 itself has a slight defect such as a scratch, or if there is a defect or a foreign substance in the shaft seal portion with the magnetic poles 2, 3 or the housing 5, the reliability of the shaft seal is deteriorated. Further, there is a problem such as vacuum permeation of the rubber ring material.

The present invention was made in order to solve the problems of the prior art as described above, and a magnetic field is formed by forming a minute gap also on the outer peripheral side of the magnetic poles 2 and 3, and a magnetic fluid is interposed to seal the shaft. The purpose of the present invention is to provide a shaft sealing device.

[0007]

In order to solve the above problems, the present invention provides a shaft seal for forming a magnetic field in a minute gap between a rotating shaft and an inner peripheral surface of a magnetic pole to retain a magnetic fluid and seal the shaft. In the mechanism, a minute gap is provided between the outer circumference of the magnetic pole and the housing, a magnetic field is formed in equilibrium with the inner circumference of the magnetic pole, and the magnetic fluid is retained to seal the shaft. A rubber ring is arranged to keep them.

[0008]

According to the above-mentioned means, the shaft sealing diameter is increased with respect to the dynamic shaft sealing between the inner circumference of the magnetic pole and the rotary shaft, but the shaft sealing is still and the shaft sealing function by the conventional rubber ring is added. It is possible to maintain a highly reliable shaft sealing function.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a shaft sealing device according to a first embodiment of the present invention. The same parts as those shown in FIG. 10 are designated by the same reference numerals and their duplicate description will be omitted.

In this embodiment, the magnetic fluid 7 is retained by the magnetic field formation by the magnet 6 in the minute gap δ provided between the inner circumference of the magnetic poles 9 and 10 and the rotary shaft 1, and these are supported via the bearing 4. A rubber ring 8 arranged between the inner surface of the housing 11 and
In addition to the shaft-sealing mechanism supported by the magnetic poles 9 and 10 that form a small gap ε with the housing 11, a magnetic field that is in equilibrium with the inner peripheral portion of the magnetic poles 9 and 10 is formed between the weak magnetic material housing 11. Of the magnetic poles 9 and 10
The shaft is sealed on the outer peripheral side. The magnetic poles 9 and 10 are shown in FIGS.
By providing the rectangular cavities 9a and the triangular cavities shown in the sectional view of FIG. 1, the magnetic field can be changed in the form of magnetic poles.

Next, FIG. 6 is a sectional view showing a shaft sealing device according to a second embodiment of the present invention. The magnetic fluid 7 on the inner peripheral side of the inner magnetic poles 12, 13 of the shaft sealing mechanism generates heat due to viscous resistance associated with the rotation of the rotating shaft 1.

In order to cool this, the magnetic poles 12 and 13 are provided with grooves 12a and 13a of rectangular cross-section shown in FIG. 6 to carry water, gas or the like as a cooling medium, and a rubber ring 8 is used to transfer water, gas or the like. The magnetic poles 12 and 13 are leak-sealed and cooled.

Next, a modified example of the second embodiment will be described with reference to FIGS.

The cross-sectional shape of the groove for carrying the water or gas body is modified so as to cool the magnetic poles 12, 13 of the second embodiment.

FIG. 7 shows an arc-shaped bottom of the groove, FIG. 8 shows a rectangular deformation to increase the cooling surface, and FIG. 9 further increases the cooling surface by forming irregularities on the wall surface of the groove. To do.

[0016]

As described above, according to the present invention, a minute gap is provided between the rotating shaft and the outer periphery of the magnetic pole and the housing, and the magnetic fluid is kept in the magnetic field equilibrium state to retain the magnetic fluid in the gap. A highly reliable shaft sealing device can be constructed by sealing the shaft with a magnetic fluid capable of relaxing vacuum penetration of the rubber ring.

Further, since the magnetic pole is deformed in its axial sectional shape, it is possible to suppress magnetic field balance and heat generation of the magnetic pole itself.

Further, the quality is improved with respect to the high peripheral speed of the equiaxed sealing device which can cool the magnetic poles by providing grooves in various shapes in the circumferential direction of the magnetic poles and flowing a coolant of water or gas. Therefore, it is possible to provide a shaft sealing device having an excellent effect of improving reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a shaft sealing device according to a first embodiment of the invention.

FIG. 2 is a cross-sectional shape modification diagram of a magnetic pole used in the first embodiment.

FIG. 3 is a cross-sectional shape modification diagram of a magnetic pole used in the first embodiment.

FIG. 4 is a cross-sectional shape modification diagram of a magnetic pole used in the first embodiment.

FIG. 5 is a cross-sectional shape modification diagram of a magnetic pole used in the first embodiment.

FIG. 6 is a sectional view of a main part of a shaft sealing device according to a second embodiment of the invention.

FIG. 7 is a modification of the groove cross-sectional shape of the coolant transport path for water, gas, etc. of the magnetic poles used in the second embodiment.

FIG. 8 is a modification of the groove cross-sectional shape of the coolant transport path for water, gas, etc. of the magnetic poles used in the second embodiment.

FIG. 9 is a modification of the groove cross-sectional shape of the coolant transport path for water, gas, etc. of the magnetic poles used in the second embodiment.

FIG. 10 is a cross-sectional view of a main part showing a conventional shaft sealing device.

[Explanation of symbols]

 1 ... Rotating shaft 2 ... Magnetic pole 3 ... Magnetic pole 4 ... Bearing 5 ... Housing 6 ... Magnet 7 ... Magnetic fluid 8 ... Rubber ring 9 ... Magnetic pole 9a ... Cavity 10 ... Magnetic pole 11 ... Housing 12 ... Magnetic pole 12a ... Rectangular cross-section groove 13 ... Magnetic pole 13a… Rectangular cross-section groove δ… Small gap ε… Small gap

Claims (2)

[Claims] 1. A bearing and a housing are supported so that a pair of magnetic poles having a gap along the axial direction of the rotating shaft are arranged with a minute gap around the rotating shaft, and between the pair of magnetic poles. In a shaft sealing device in which a plurality of magnets are interposed in the circumferential direction and a magnetic fluid is interposed in the minute gap, a rubber ring is placed between the outer circumference of the magnetic pole and the housing, and a minute gap is also provided here. A shaft sealing device characterized in that a magnetic fluid is interposed to seal the shaft both inside and outside the magnetic pole. 2. The shaft sealing device according to claim 1, wherein the grooves generated in the circumferential direction of the magnetic poles are provided to allow cooling water to pass therethrough, thereby cooling the heat generated by the shaft sealing material with the rotary shaft. .