JPH0614493A - Shaft sealing equipment - Google Patents

Abstract

PURPOSE:To prevent foreign materials such as a broken piece of a magnet from coming into a small space between a rotary shaft and a magnetic pole where a magnetic fluid exists and then being mixed in the magnetic fluid. CONSTITUTION:Pairs of magnetic poles 2, 3 which are formed at a little distance along an axial direction of a rotary shaft 1 are located around the rotary shaft 1 with a little space delta formed between the rotary shaft 1 and the magnetic poles. Between the magnetic poles 2 and 3 in each pair, tame plurality of magnets are set in the circumferential direction. In the little space delta, a magnetic fluid exists. In such a shaft sealing equipment, at least a face of at least one magnet 4 which faces the rotary shaft 1 is covered and a shielding body 11 which shields a space between each magnet 4 and the little space delta is installed.

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 for vacuum or gas sealing by axially sealing a rotating machine using a magnetic fluid around a rotary shaft, and more specifically, to a rotary machine in which a magnetic fluid is interposed. The present invention relates to a technique for preventing foreign matter such as magnet fragments from entering a minute gap between a shaft and a magnetic pole and mixing with a magnetic fluid.

[0002]

2. Description of the Related Art In recent years, the momentum of development of a shaft sealing device using magnetic fluid has been increasing, and in particular, in a rotating machine, applying a magnetic fluid seal around the rotating shaft reduces the size as a rotational non-contact structure. And since it can improve reliability, it is being actively developed.

16 and 17 (cross-sectional view taken along the line CC in FIG. 16) show an example of a conventional shaft sealing device used in a rotary machine. In these drawings, 1 is a rotary shaft of a rotary machine, and a pair of magnetic poles 2 and 3 spaced apart along the axial direction of the rotary shaft 1 are arranged around the rotary shaft 1 with a minute gap δ. A plurality of magnets 4 are provided in the circumferential direction between the magnetic poles 2 and 3, and a magnetic fluid 5 is interposed in the minute gap δ. That is, a magnetic field is formed by the magnet 4 from the one magnetic pole 2 to the rotary shaft 1 and then to the other magnetic pole 3, and a magnetic field is formed in the minute gap δ between the magnetic poles 2 and 3 and the rotary shaft 1. Then, the magnetic fluid 5 is interposed between the rotary shaft 1 and the magnetic poles 2 and 3 so that the rotary shaft 1 and the magnetic poles 2 and 3 are not in contact with each other and the shaft is sealed. The magnetic poles 2 and 3 are fixed to the housing 6 of the rotary machine.

[0004]

By the way, in such a device which seals with a magnetic fluid in a rotating non-contact manner, the magnetic fluid to be used has various characteristics such as the characteristics of the magnetic fluid itself, the strength of the magnetic field, and the rotating peripheral speed. The value of the minute gap between the magnetic pole and the rotary shaft is properly determined. However, if a substance other than the magnetic fluid is present in the minute gap, the magnetic fluid is destroyed and its characteristics are impaired. Further, even if the magnetic fluid is sound, if solid foreign matter is present or enters the minute gap between the magnetic pole and the rotary shaft, the gap (shaft seal part) is damaged and the shaft seal device itself is destroyed. I will end up.

However, in the conventional shaft sealing device shown in FIGS. 16 and 17, it is possible to prevent fragments of the magnet 4 or other foreign matter from entering the minute gap δ between the magnetic poles 2 and 3 and the rotary shaft 1. Since no special configuration is adopted, the debris of the magnet 4 or other foreign matter enters the minute gap δ between the magnetic poles 2 and 3 and the rotating shaft 1 and mixes with the magnetic fluid 5, so that the shaft sealing function is improved. Not only is it hindered, but the gap δ is damaged and the shaft sealing device itself is broken.

In particular, since the magnet 4 is generally made of a hard and brittle material, cracks and fragments are likely to occur due to axial force, rotational vibration of the shaft system, or some other condition, and the minute gap Since δ is a magnetic field, fragments of the magnet 4 and magnetic powder often intrude into the minute gap δ between the magnetic poles 2 and 3 and the rotating shaft 1.

The present invention has been made in order to solve the problems of the prior art as described above, and foreign matter such as fragments of magnets intrudes into a minute gap between the rotating shaft and the magnetic pole in which the magnetic fluid intervenes. An object of the present invention is to provide a shaft sealing device that is prevented from being mixed with a magnetic fluid.

[0008]

In order to solve the above-mentioned problems, the present invention has a pair of magnetic poles arranged at intervals along the axial direction of a rotary shaft with a minute gap around the rotary shaft. In addition, in a shaft sealing device in which a plurality of magnets are interposed in the circumferential direction between the pair of magnetic poles and a magnetic fluid is interposed in the minute gap, at least one magnet faces at least the rotating shaft. A shield that covers the surface and shields between each magnet and the minute gap is provided.

[0009]

According to the above means, since a shield is provided between each magnet and the minute gap between the magnetic pole and the rotary shaft to shield them from each other, foreign matter such as broken pieces of the magnet can be eliminated. Since it will not enter the gap and mix into the magnetic fluid, a sound shaft sealing function can be maintained.

[0010]

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, and FIG. 2 is a sectional view taken along the line AA of FIG. 1, which is the same as that shown in FIGS. The same parts are designated by the same reference numerals, and duplicate description will be omitted.

In this embodiment, a plurality of magnets 4 and magnetic poles 2, 3 are used.
Further, a thin cylindrical or ring-shaped shield 11 made of a non-magnetic material is used as a shield that shields between the minute gap δ between the rotating shafts 1. The shield 11 is in contact with and covers the inner peripheral side of the annular magnet assembly of the plurality of magnets 4 arranged around the rotation axis 1, that is, the surface of each magnet 4 facing the rotation axis 1. And is placed on the protrusions 12 and 13 formed on the opposite side surfaces of the pair of magnetic poles 2 and 3. Therefore, the shield 11 shields each magnet 4 from the minute gap δ between the magnetic poles 2 and 3 and the rotary shaft 1, and the fragments or magnetic powder of the magnet 4 separate the magnetic poles 2 and 3 from the rotary shaft 1. This prevents the magnetic fluid 5 from entering the minute gap δ between them and mixing into the magnetic fluid 5.

By forming the shield 11 from an elastic material, the close contact with the magnetic poles 2 and 3 can be strengthened to further enhance the shielding effect, and the cross-sectional shape is not limited to the rectangular shape shown in FIG. However, it can be formed into various shapes such as a circular shape as shown in FIGS. 3A, 3B and 3C, and as shown in FIG. It is also possible to apply the adhesive 14 to the surface on the side to be adsorbed to absorb the foreign matter.

Next, FIG. 4 is a cross-sectional view of an essential part showing a shaft sealing device according to a second embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along the line BB of FIG. 4, and FIGS. The same parts as those shown are designated by the same reference numerals, and duplicate description will be omitted.

In this embodiment, a plurality of magnets 4 and magnetic poles 2, 3 are used.
And a shield for shielding between the minute gap δ between the rotating shaft 1
As the above, a plurality of shields (covers) 21 that completely cover each magnet 4 independently are used, and each shield 21 is formed of a nonmagnetic magnetic force transmitting material. These shields 21 cover the magnet 4 to prevent scattering of fragments when the magnet 4 is cracked or broken.
This prevents fragments of the magnet 4 from entering the minute gap δ between the magnetic poles 2 and 3 and the rotating shaft 1 and mixing with the magnetic fluid 5. Further, these shields 21 protect the magnets 4 which are easily broken and facilitate their handling. Next, a modified example of the second embodiment will be described with reference to FIGS.

First, in the second embodiment, the plurality of magnets 4 are independently covered with the plurality of shields 21, respectively.
And all magnets 4 are covered with a single doughnut-shaped shield 22 as shown in FIG. 7, or the shield 22 is divided into several pieces in the circumferential direction as shown in FIG. Can be coated in groups of several to make handling and assembly easier.

In addition, in the second embodiment, the entire magnet 4, that is, the outer peripheral surface and both side surfaces thereof are completely covered with the respective shields 21, but as shown in FIGS. The magnet 4 may be surrounded by a shield 23 that covers only the surface to make handling and assembly easier and to make the side surface of the magnet 4 visible. When the shield 23 is made of an elastic material, the axial length of the shield 23 is made longer than that of the magnet 4 by the shrinkage margin of the elastic material, as shown in FIG.

Further, in FIGS. 9 to 11, the outer peripheral surfaces of the plurality of magnets 4 are individually surrounded by the plurality of shields 23. However, as shown in FIGS. 12, 13 and 14, these independent shields are provided. A shield 24 in which all the magnets 4 are loaded is provided by connecting the bodies 23, or the shield 24 is divided into several pieces in the circumferential direction as shown in FIG. It may also be easier to handle and assemble.

[0019]

As described above, according to the present invention, a pair of magnetic poles spaced apart along the axial direction of the rotary shaft are arranged with a minute gap around the rotary shaft, and the pair of magnetic poles are arranged. 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, each magnet covers at least a surface facing a rotation axis of each magnet. Since a shield is provided to shield between the magnet and the minute gap to prevent foreign matter such as magnet fragments from entering the minute gap, it is possible to prevent foreign matter such as magnet fragments from entering the magnetic fluid. As a result, a sound shaft sealing function can be maintained, and therefore, the quality of the shaft sealing device using the magnetic fluid can be improved, and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a shaft sealing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

3 (a), (b), (c) and (d) are cross-sectional views of a main part showing a modified example of the shield used in the first embodiment.

FIG. 4 is a cross-sectional view of essential parts showing a shaft sealing device according to a second embodiment of the present invention.

5 is a sectional view taken along line BB of FIG.

FIG. 6 is a cross-sectional view of a main part showing a modified example of the shield used in the second embodiment.

FIG. 7 is a partial side view of FIG.

FIG. 8 is a diagram showing a modification of FIG. 7.

FIG. 9 is a cross-sectional view showing another modification of the shield used in the second embodiment.

FIG. 10 is a side view of FIG. 9.

FIG. 11 is a diagram showing a modification of FIG. 9.

FIG. 12 is a cross-sectional view showing still another modified example of the shield used in the second embodiment.

FIG. 13 is a diagram showing a modified example of FIG.

FIG. 14 is a side view of FIG. 12 or FIG.

FIG. 15 is a diagram showing a modified example of FIG.

FIG. 16 is a cross-sectional view showing a conventional shaft sealing device.

17 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary shaft 2, 3 magnetic poles 4 magnets 5 magnetic fluid 6 housing 11 shields 12, 13 protrusions 14 adhesives 21, 22, 23, 24 shield δ minute gap between magnetic poles and rotary shafts

Claims (1)

[Claims] 1. A pair of magnetic poles spaced apart along the axial direction of a rotating shaft are arranged with a minute gap around the rotating shaft, and a plurality of magnets are circumferentially arranged between the pair of magnetic poles. In a shaft sealing device in which a magnetic fluid is interposed in the minute gaps, at least one surface of at least one magnet facing the rotation axis is covered to shield each magnet from the minute gaps. A shaft sealing device, which is provided with a shield.