JPH0718411A - Rotating power transmitting mechanism for vacuum device - Google Patents

Abstract

PURPOSE:To provide a small-sized and inexpensive rotating power transmitting mechanism for a vacuum device. CONSTITUTION:A sealing function against the differential pressure between the vacuum atmosphere and atmospheric pressure atmosphere is realized by a greased vacuum seal unit 2. Meanwhile, a magnetic-fluid seal 3 is incorporated on the vacuum side of the unit 2. A magnetic fluid 17 is held by the unit 3, and a closed structure is realized. The discharge to the vacum atmosphere side of an extremely small amt. of the tiny mist of a vacuum grease 14 generated a companied with the rotation of shaft is prevented by the closed structure. An opening 6a is formed at the part of a housing 5 corresponding to the clearance between the unit 2 and seal 3, and an exchangeable clean filter cartridge 6 is inserted into the opening 6a. Consequently, the service life of the seal 3 is prolonged, and the seal is not deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary power transmission mechanism, and more particularly to a rotary power transmission mechanism provided in a partition wall of a vacuum device, which isolates a vacuum atmosphere and an atmospheric pressure atmosphere from each other. The present invention relates to a rotary power transmission mechanism that transmits power to vacuum equipment.

[0002]

2. Description of the Related Art Conventionally, as a rotary power transmission mechanism of this type, there is one shown in FIGS. 2 and 3, which will be sequentially described below.

As shown in FIG. 2, this rotary power transmission mechanism includes a shaft 21 for transmitting rotary power to a vacuum device inside a vacuum device, a multistage magnetic fluid seal row 22 through which the shaft 21 penetrates, and a shaft. It has a bearing 23 that holds 21 for rotation, a housing 24 that houses the shaft 21, the magnetic fluid seal row 22, and the bearing 23. This housing 24 is the partition wall 1 of the vacuum device.
9 is provided between the housing 24 and the partition wall 19.
A ring 29 is provided. Also, the housing 24
Of the end of the vacuum atmosphere side and the atmospheric pressure atmosphere side.
a and 24b are fixed to each other by means such as bolts.

The magnetic fluid seal row 22 incorporated in the shaft 21 is sandwiched between the pole piece 25 and a ring-shaped pole piece 25 having an inner diameter having a clearance of about 0.1 mm with respect to the diameter of the shaft 21 for each row. The magnetic fluid 27 is held in the gap between the shaft 21 and the pole piece 25 by the magnetic force generated by the magnet 26. The film of the magnetic fluid 27 is 200 to 200 per one step of the magnetic fluid seal.
Since a differential pressure of about 400 mmH ₂ O can be received, by stacking in multiple stages as described above, a sealing effect is exhibited as a whole against the differential pressure (1 atm) of the vacuum atmosphere. Reference numeral 28 indicates a spacer provided for each row of magnetic seals. The shaft 21 is rotatably held by a bearing 23, and the rotational power can be transmitted only by receiving an extremely small viscous resistance from the magnetic fluid when rotating (a technique similar to this technique is disclosed in, for example, Japanese Patent Laid-Open No. Sho 3-1980). No. 62-33681, Japanese Patent Laid-Open No. 1-116065
JP-A No. 2-65095, etc.).

As shown in FIG. 3, this rotary power transmission mechanism includes a shaft 31 for transmitting rotary power and a grease-sealed vacuum seal unit 32 through which the shaft 31 penetrates.
A bearing 33 for holding the shaft 31 in rotation, and the shaft 31 and a grease-sealed vacuum seal unit 3
2 and a housing 34 that houses the bearing 33. The housing 34 is a partition 19 of the vacuum device.
An O-ring 39 is provided between the housing 34 and the partition wall 19. Also, in the housing 34,
At the ends of the vacuum atmosphere side and the atmospheric pressure atmosphere side, a lid 34a,
34b are fixed to each other by means such as bolts.

The grease-sealed vacuum seal unit 32 is
A grease reservoir 37 is provided between the two O-rings 35 and the backup ring 36, and a sealing effect is provided by the O-ring 35 via a thin film of vacuum grease 38 having an extremely low vapor pressure, and at the same time the grease reservoir is provided. The vacuum grease 38 in 37 also seals and improves the sealing effect. As a result, one stage of the grease-sealed vacuum seal unit 32 can receive a pressure difference of 1 atm. Since the shaft 31 is rotatably held by the bearing 33, the rotational power can be transmitted only by receiving the sliding resistance of the O-ring 35 and the viscous resistance of the vacuum grease 38 when rotating.

[0007]

Among the above-described conventional rotary power transmission mechanisms for a vacuum device, the one shown in FIG. 2 has a small differential pressure received by one stage of the magnetic fluid seal, and therefore has a pressure of 1 atm. In order to receive the differential pressure of, the magnetic fluid seal must be laminated in about 20 to 40 steps, and as a result,
Increasing the size of the shaft in the axial direction is inevitable. Also,
The cost of the magnetic fluid seal is several steps higher than that using a normal O-ring, and as a result, there is a problem that the cost increases.

On the other hand, the one shown in FIG. 3 has a problem that the vacuum grease becomes minute droplets and is discharged to the vacuum atmosphere side even though the amount is very small, and the cleanliness is lowered.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a rotary power transmission mechanism for a vacuum device which is small in size and inexpensive in cost.

[0010]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a rotary power transmission mechanism of a vacuum device for transmitting rotary power to vacuum equipment inside a vacuum device, and a shaft for transmitting rotary power. A grease-filled vacuum seal unit through which the shaft penetrates, and a magnetic fluid seal arranged on the vacuum side of the grease-filled vacuum seal unit,
A bearing that holds the shaft in rotation, a housing that accommodates the shaft, the grease-filled vacuum seal unit, the magnetic fluid seal, and the bearing, and that is provided in a partition wall of a vacuum device; A vacuum filter unit and a clean filter cartridge incorporated in a gap between the magnetic fluid seals are provided.

[0011]

In the present invention configured as described above, the grease-filled type vacuum seal unit realizes a sealing function against the differential pressure between the vacuum atmosphere and the atmospheric pressure atmosphere. On the other hand, since the magnetic fluid seal is built into the vacuum side of the grease-filled vacuum seal unit, this sealed structure allows the extremely small amount of vacuum grease generated with the rotation of the shaft to move toward the vacuum atmosphere side of minute droplets. Prevent exhaust of.

On the other hand, regarding the magnetic fluid seal,
Since the differential pressure resistance per step is about 200 to 400 mmH ₂ O, if this condition is maintained, the air present in the gap between the grease-filled vacuum seal unit and the magnetic fluid seal will be reduced when the vacuum side is depressurized from atmospheric pressure. There is a possibility that minute droplets of vacuum grease may be exhausted to the vacuum atmosphere side while passing through the membrane holding the magnetic fluid in the form of bubbles, and may mix with the magnetic fluid and deteriorate the life and performance of the magnetic fluid seal. . Therefore,
In the present invention, a clean filter cartridge is installed in a portion of the housing corresponding to a gap between the grease-filled vacuum seal unit and the magnetic fluid seal, and when the gas inside the vacuum container is depressurized, a gap between the grease-filled vacuum seal unit and the magnetic fluid seal is provided. The air existing in the air passes through the clean filter cartridge, and only the clean air is discharged to the outside of the housing.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view of an essential part of a rotary power transmission mechanism of a vacuum device according to the present invention.

As shown in FIG. 1, inside the grease-sealed vacuum seal unit 2, a grease reservoir 13 is formed in a portion sandwiched by two sets of O-rings 11 and backup rings 12, and the grease reservoir 13 is filled with grease. Is filled with vacuum grease 14. Therefore, the shaft 1 rotatably held by the bearing 4 penetrates the grease-sealed vacuum seal unit 2 so as to come into close contact with the O-ring 11 via the thin film of the vacuum grease 14, and at the same time, the grease reservoir 13
The vacuum grease 14 in the inside adheres. As a result, the grease-sealed vacuum seal unit 2 realizes a sealing function against the pressure difference between the vacuum atmosphere and the atmospheric pressure atmosphere.

On the other hand, a grease-sealed vacuum seal unit 2
The magnetic fluid seal 3 is incorporated on the vacuum side of the. The magnetic fluid seal 3 has a clearance of about 0.1 mm with respect to the diameter of the shaft 1, and is composed of a pair of ring-shaped pole pieces 15 and a ring-shaped magnet 16 sandwiched between the pole pieces 15. The magnetic force generated by the magnet 16 causes the shaft 1 and the pole piece 15 to move.
The magnetic fluid 17 is held between it and the inner diameter to realize a closed structure. The magnetic fluid seal 3 may be provided in several stages so that the rotary power transmission mechanism does not become large. With this sealed structure,
This prevents the extremely small amount of vacuum grease 14 generated by the rotation of the shaft 1 from being discharged to the vacuum atmosphere side. The housing 5 accommodates the shaft 1, the grease-sealed vacuum seal unit 2, the magnetic fluid seal 3 and the bearing 4, and is provided on the partition wall 19 of the vacuum device. An O-ring 18 is provided between the housing 5 and the partition wall 19. Further, lids 5a and 5b are fixed to the ends of the housing 5 on the vacuum atmosphere side and the atmospheric pressure atmosphere side by means such as bolts.

With respect to the magnetic fluid seal 3 described above, since the differential pressure resistance per stage is about 200 to 400 mmH ₂ O, if this condition is maintained, a grease-filled type vacuum seal is used when the vacuum side is depressurized from atmospheric pressure. The air existing in the gap between the unit 2 and the magnetic fluid seal 3 passes through the film holding the magnetic fluid 17 in the form of bubbles, and at the same time, the minute droplets of the vacuum grease 14 are discharged to the vacuum atmosphere side, or the magnetic fluid is discharged. There is a risk that the life and performance of the magnetic fluid seal 3 may be deteriorated by mixing with the magnetic fluid 17. Therefore, in this embodiment, an opening 6a is formed in a portion of the housing 5 corresponding to the gap between the grease-filled vacuum seal unit 2 and the magnetic fluid seal 3, and the replaceable clean filter cartridge 6 is fitted into the opening 6a. When the gas inside the vacuum container on the vacuum side is decompressed, the air present in the gap between the grease-filled vacuum seal unit 2 and the magnetic fluid seal 3 is discharged to the outside of the housing 5 via the clean filter cartridge 6, It is possible to prevent the deterioration of the life and the performance described above. When the air passes through the clean filter cartridge 6, minute splashes of grease or the like are captured by the clean filter cartridge 6, and only clean air is discharged to the outside of the housing 5.

The above-mentioned clean filter cartridge is, for example, an existing SS-4F manufactured by NUPRO Co., Ltd.
WS (trade name) may be used, or one made of a material such as a HEPA filter may be used. Further, the location where the clean filter cartridge is provided is not limited to one location, and it is effective to provide it at a plurality of locations. Furthermore, it is preferable to replace the clean filter cartridge periodically at predetermined intervals, although it depends on the size and the number of the clean filter cartridges.

[0018]

As described above, the present invention uses the functions of the conventional grease-filled vacuum seal unit and the magnetic fluid seal, and uses the housing in the gap between the grease-filled vacuum seal unit and the magnetic fluid seal. Since the rotary power transmission mechanism is realized by using the built-in clean filter cartridge, it is possible to provide a rotary power transmission mechanism that is small in size and low in cost and does not deteriorate the life and performance of the magnetic fluid seal. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of an embodiment of a rotary power transmission mechanism of a vacuum device according to the present invention.

FIG. 2 is a sectional view of a main part of a conventional rotary power transmission mechanism of a vacuum device.

FIG. 3 is a sectional view of a main part of another conventional rotary power transmission mechanism of a vacuum device.

[Explanation of symbols] 1 shaft 2 grease enclosed vacuum seal unit 3 magnetic fluid seal 4 bearing 5 housing 5a, 5b lid 6 clean filter cartridge 6a opening 11 O-ring 12 backup ring 13 grease reservoir 14 vacuum grease 15 pole piece 16 magnet 17 magnetic fluid 18 O-ring 19 partition wall

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[Procedure amendment]

[Submission date] November 9, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (1)

[Claims] 1. A rotary power transmission mechanism for a vacuum device, which transmits rotary power to vacuum equipment inside the vacuum device, a shaft for transmitting the rotary power, a grease-sealed vacuum seal unit through which the shaft penetrates, A magnetic fluid seal arranged on the vacuum side of the grease-filled vacuum seal unit; a bearing for rotating and holding the shaft; the shaft; the grease-filled vacuum seal unit;
A housing for accommodating the magnetic fluid seal and the bearing and provided in a partition wall of a vacuum device; and a clean filter cartridge incorporated in a gap between the grease-sealed vacuum seal unit and the magnetic fluid seal of the housing. A rotary power transmission mechanism for a vacuum device, characterized in that