JPS60155063A - Magnetic-fluid seal device - Google Patents

Abstract

PURPOSE:To improve the seal performance by providing a film made of magnetic fluid on an annular lug formed on a bush or a pole piece and communicating a seal chamber to a hermetically sealed chamber with a switching valve in a magnetic-fluid seal device. CONSTITUTION:An annular lug 3 is formed on the surface of a rotary shaft 2, and when a magnetic fluid is injected, the magnetic fluid is stuck between the inner periphery of a pole piece 5 and the outer periphery of the annular lug 3 to form a ring-like film 11, and a seal chamber 12 is formed. In addition, the seal chamber 12 is communicated to a vacuum chamber 15 as a hermetically sealed chamber with a pipeline 13, and a switching valve 14 is provided in the middle of the pipeline 13. Accordingly, the hermetically sealed chamber and the seal chamber communicated to this hermetically sealed chamber have the same pressure, and even when the seal capability of the film is deteriorated by the disturbance such as the vibration of the rotary shaft, the hermetically sealed chamber is completely cut off from the outside air, and the initial chamber pressure can be maintained.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a magnetic fluid sealing device used, for example, in a device in which a rotating shaft is inserted from the outside into a vacuum container. It's about improvement.

[Prior art]

FIG. 1 is a new view of a conventional magnetic fluid seal device,
A rotating shaft made of a non-magnetic material is provided on the central axis of the cylindrical casing. This rotating shaft has a plurality of rectangular annular protrusions 3 (hereinafter referred to as fringe) on its surface.
A magnetic bushing V is fitted therein.

A pair of pole pieces 5 are provided on the outer periphery of the bushing at a constant interval in the radial direction and spaced apart in the axial direction. A pair of rolling bearings 6 are provided on the inner circumference of one of the pole pieces 3 to rotatably support a rotating shaft. A cylindrical magnet is held between a pair of spaced apart pole pieces. Paul peace! A groove g is formed in the circumferential direction on the outer peripheral wall of. This groove ffKo ring 9 is provided so that a stable seal can be obtained between the casing l and the pole piece. Furthermore, i.

is a spacer made of a non-magnetic material that separates the bushing and the rolling bearing 6.

Next, we will explain the operation of the magnetic fluid seal device with the above configuration.
I will clarify. Due to the magnetic action of the magnet 7, an elliptical magnetic circuit (not shown) is formed that passes through the magnet, the left pole pieces, and the bush q. Furthermore, since a plurality of fringes 3 are provided between the left inner circumferential surface of the pole piece and the outer circumferential surface of the book, the magnetic density is high in the fringe 3 portion of the above magnetic circuit. Therefore, Fringe 3
When a magnetic fluid is injected into the vicinity, the magnetic fluid adheres between the inner circumferential surface of the pole piece S and the outer circumferential surface of the tip of the fringe 3, forming a ring-shaped film l/, and forming a plurality of seal chambers/ Therefore, for example, a vacuum chamber l is defined as a sealed chamber cut off from the atmosphere on the right side of this apparatus shown in FIG.
When S is installed in series, the air will get oil around the rotating shaft 2 and try to flow into the vacuum chamber ls, but at that time, the flow of air is blocked by 11J/ /, and the vacuum inside the vacuum chamber lj is maintained. At the same time, the rotating shaft becomes rotatable.

The conventional magnetic fluid sealing device is constructed as shown below. For example, when trying to withstand vacuum (gauge pressure -/made) in the vacuum chamber IS with a total of six stages of fringe 3, three on the left and right, Assuming that the sealing capacity of H7Jt/ in each stage is 02S~, the pressure distribution in each seal chamber/2 is K as shown in Figure 1.
Become. As can be seen from this figure, there is an atmosphere with a gauge pressure of -0 phthalate in the seal chamber between the first and second stage fringes 3, and the sealing capacity is slightly reduced due to disturbances such as vibrations of the rotating shaft. 3) If the pressure decreases, the atmosphere in the sealing chamber 1 leaks into the vacuum chamber tS, resulting in the destruction of the high vacuum in the vacuum chamber ls.

[Summary of the invention]

This invention was made for the purpose of eliminating the above-mentioned drawbacks, and a plurality of annular protrusions formed on either the outer circumferential surface of the bushing or the inner circumferential surface of the pole piece are connected to the outside air and a pressure lower than this outside air. A ring-shaped membrane made of magnetic fluid is provided to cut off the flow of outside air between the sealed chamber having an atmosphere of A magnetic fluid seal device that communicates via an on-off valve, so even if the sealing ability of the membrane decreases due to disturbances such as vibrations of the rotating shaft, the sealed chamber is completely cut off from the outside air, improving sealing performance. It provides:

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetic fluid sealing device of the present invention will be described below with reference to the drawings. FIG. 3 is a sectional view showing an embodiment of the present invention, and is the same as that in FIG.

A sealing chamber between the first and second stage fringe 3 and a vacuum chamber as a sealed chamber! A piping 13 communicates with the left side, and an on-off valve /F that can be opened and closed manually or automatically is provided in the middle of the piping /3.

In the magnetic fluid seal device configured as described above, for example, when trying to withstand the vacuum (gauge pressure -75) K in the vacuum chamber 13 with a total of six stages of fringe 3, three on the left and right, the vacuum chamber /, If the opening/closing valve /F is opened when the inside of r is gradually evacuated with a vacuum pump, the pressure between the first and second stage fringes 3 becomes vacuum as well as the vacuum chamber 15, and each seal chamber /2 The pressure distribution is as follows: 1st stage sealing capacity is 0.25 yen
Then, it becomes as shown in Fig. v. In this state, the on-off valve/
If the rotating shaft is rotated after closing F, even if the sealing ability of the membrane decreases due to disturbances such as vibration of the rotating shaft, the seal between the fringe 3 of the second and third stages will be maintained. A portion of the atmosphere (gauge pressure - oqr%) in chamber/2 is transferred to the first and second stages.
It only leaks into the seal chamber/2 between the fringe 3 and the stage, but not into the vacuum chamber IS. In other words, there is no risk that the high vacuum in the vacuum chamber IS will be destroyed even at a temperature of 0.degree.

In the above embodiment, the fringe 3 is provided on the pusher, but the outer circumferential surface of the pusher may be made smooth and the fringe may be provided on the inner circumferential surface on the left side of the pole piece.

Furthermore, as shown in Fig. One rolling bearing can be attached to each to support the rotating shaft. Furthermore, in this embodiment, a piping 13 was provided between the vacuum chamber /Yo and the seal chamber /2 adjacent to the vacuum chamber 1svc, and this piping was connected to the vacuum chamber /S, the first stage and the third stage. Fringe with steps 3
Even if the space is communicated with the seal chamber 7.2 in between, the same effect as in the above embodiment can be obtained. Furthermore, in the above embodiment, the pressure inside the sealed chamber is reduced to a vacuum (gauge pressure -7o) in the atmosphere.
Although the explanation has been given on the case where the air pressure is maintained at a constant pressure in the outside air, it goes without saying that it can also be used to protect a sealed chamber having an atmosphere at a lower pressure than the outside air from the outside air.

〔Effect of the invention〕

As explained above, according to the magnetic fluid sealing device of the present invention, the plurality of annular protrusions formed on either the outer peripheral surface of the bushing or the inner peripheral surface of the pole piece are connected to the outside air and the lower pressure than the outside air. A ring-shaped membrane made of magnetic fluid is provided to cut off the flow of outside air between the sealed chamber containing the atmosphere, and the sealed chamber is opened and closed with one of the multiple sealed chambers defined by this membrane. By communicating through the valve, the sealed chamber and the seal chamber that communicates with this sealed chamber have the same pressure, so even if the sealing ability of the membrane decreases due to disturbances such as vibrations of the rotating shaft, the sealed chamber will remain in the sealed chamber. is completely cut off from the outside air and has the effect of maintaining the initial room pressure.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional magnetic fluid seal device, Fig. 1 is a pressure distribution diagram of each seal chamber thereof, Fig. 3 is a sectional view showing an embodiment of the present invention, and Fig. V is a sectional view of each seal chamber thereof. FIG. L...Casing, λ...Rotation shaft, Jee annular projection (fringe), Ter bush, 5...Pole piece, 7...Magnet, //...Membrane, 12...Seal chamber, 13...
・Piping, /Socket・On-off valve, /, 1...Vacuum chamber (sealed chamber)
. In each figure, the same reference numerals indicate the same or corresponding parts. (9) (za) -1 → 392- crush

Claims (2)

[Claims] (1) A non-magnetic rotating shaft, a cylindrical magnetic bushing fitted to the rotating shaft, supporting the rotating shaft via a bearing, and having a distance of one foot in the radial direction from the bushing. a pair of magnetic pole pieces placed apart from each other in the axial direction; an annular magnet held between the pair of pole pieces so as to be concentric with the rotation axis; A cylindrical casing provided on both outer peripheries of the magnet and the pole piece, and a plurality of rectangular casings formed on either the circumferential surface of the pole piece or the outer circumferential surface of the bushing opposite thereto. A plurality of ring-shaped films are formed between the pole piece and the bushing with the magnetic fluid injected into the annular projection where the magnetic flux of the magnet is concentrated. In a magnetic fluid sealing device that interrupts the flow of outside air between outside air and a sealed chamber having an atmosphere at a lower pressure than the outside air, one of the plurality of seal chambers defined by the membrane and the sealed chamber A magnetic fluid seal device characterized in that the two are communicated via an on-off valve. (2) The magnetic fluid sealing device according to claim 1, wherein one of the sealing chambers is a sealing chamber adjacent to the sealed chamber IC.