JPH02271167A - Seal construction of rotary shaft for vacuum device - Google Patents

Abstract

PURPOSE:To completely prevent an air ingress in a vacuum chamber by provid ing a seal chamber having a rotary shaft inserted and containing oil sealed at low vapor pressure at the outside of the vacuum chamber, and a seal cham ber and a rotary shaft seal member for sealing the rotary shaft respectively at both sides of the seal chamber. CONSTITUTION:A housing 1 having an internal vacuum chamber 2 is provided with a rotary shaft 3 in such a way that one end of the shaft 3 comes to be located in the vacuum chamber 2 and the other end projected to the atmosphere 4. A seal case 11 coupled to the rotary shaft 3 is fitted to the external surface of the housing 1, and a seal chamber 13 to have the rotary shaft 3 inserted, is provided at the intermediate part of the case 11. Recess parts 14 and 15 are formed on both inner and outer sides of the seal chamber 15, and the rotary shaft 5 and seal members 21 and 22 are mounted. In addition, oil 16 having low vapor pressure is sealed in the seal chamber 13. According to the aforesaid construction, the ingress of the atmosphere 4 into the vacuum chamber 2 is completely prevented with the oil 16 and the seal members 21 and 22, and the inside of the vacuum chamber 2 can be maintained at a high vacuum degree and in a clean condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary shaft seal structure for a vacuum device such as an oil-free vacuum pump.

[Conventional technology]

For example, in vacuum devices such as vacuum pumps, it is common to seal the rotating shaft using a rotating shaft sealing member such as an oil seal or a mechanical seal.

FIG. 3 is a sectional view showing a conventional rotary shaft seal structure, and 1 is a housing having a vacuum chamber 2 inside. The rotating shaft 3 has one end facing into the vacuum chamber 2 and the other end protruding into the atmosphere 4, and is interposed between the vacuum chamber 2 and the atmosphere 4. 5 is a rotary shaft sealing member such as an oil seal or a mechanical seal that seals the rotary shaft 3, and the atmosphere 4 is connected to the vacuum chamber 2.
Prevents intrusion into the interior. A seal case 6 holds the rotary shaft seal member 5, and is attached to the housing 1 with a screw or the like via a fixed seal 7 such as an O-ring.

[Problem to be solved by the invention]

However, such a structure in which sealing is performed using only the rotary shaft sealing member does not necessarily provide reliable sealing against gas, and there is a problem in that the atmosphere enters the vacuum chamber along the rotary shaft. Furthermore, this makes it extremely difficult to maintain a high vacuum inside the vacuum chamber.

The present invention was made in view of the above circumstances, and an object thereof is to provide a rotary shaft seal structure for a vacuum device that can more reliably prevent atmospheric air from entering a vacuum chamber.

[Means to solve the problem]

The rotary shaft seal structure according to the present invention has a seal chamber in which the rotary shaft is inserted through the vacuum chamber and is filled with low vapor pressure oil, and seals are formed between the seal chamber and the rotary shaft on both sides of the seal chamber. A rotary shaft seal member is provided.

[Effect]

In the present invention, air entering the vacuum chamber is reliably sealed with oil in the seal chamber, and oil is prevented from leaking from the seal chamber by the rotary shaft seal member.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the rotary shaft seal structure of a vacuum device according to the present invention. , the other end protrudes into the atmosphere 4 and is interposed between the vacuum chamber 2 and the atmosphere 4.

Reference numeral 11 denotes a seal case formed into a substantially cylindrical shape and fitted onto the rotary shaft 3, which is attached to the outer surface of the housing 1 coaxially with the rotary shaft 3 by a screw or the like passing through a flange 12 provided on the housing l side. installed on. A seal chamber 13 into which the rotary shaft 3 is inserted is formed in the center of the seal case 11, and recesses 14 and 15 are formed inside and outside the seal chamber 13. Said seal chamber 1
3 is filled with a low vapor pressure oil 16 such as fluorine thread oil. Reference numeral 17 denotes an oil supply port provided in the seal case 11 for injecting oil 16 into the seal chamber 13, and is closed with a stopper 18 except when oil is being filled.

21 is a rotating shaft sealing member attached to the recessed portion 14;
Reference numeral 22 denotes a rotary shaft sealing member attached to the concave portion 15, which is composed of an oil seal, a mechanical seal, etc., and seals between the seal chamber 13 and the outer peripheral surface of the rotary shaft 3. This prevents the liquid from leaking out of the seal chamber 13. 23 is the rotary shaft sealing member 2 on the atmosphere side
2, and is attached to the outer opening edge of the seal case 11 with screws or the like. 24 and 25 are fixed seals made of O-rings, etc., which are installed between the rotating shaft seal member 21 and the housing 1, between the rotating shaft seal member 21 and the seal case 11, and between the rotating shaft seal member 22 and the seal presser 23. During this period, the space between the rotary shaft seal member 22 and the seal case 11 is sealed to prevent atmospheric air from entering the vacuum chamber 2 through the gap between these members.

In the rotary shaft seal structure of the vacuum device configured in this way, the oil 16 sealed in the seal chamber 13 is interposed between the atmosphere 4 and the vacuum chamber 2, so this oil 16 causes the atmosphere 4 to flow into the vacuum chamber. 2 can be prevented from entering. Further, leakage of the oil 16 from the seal chamber 13 to the atmosphere 4 side or the vacuum chamber 2 side can be prevented by the rotary shaft seal members 21 and 22. Here, since the sealing effect of the rotary shaft seal members 21 and 22 against the oil 16 is much higher than that of a gas seal, the leakage of the oil 16 can be made extremely small, and the oil 16 can be injected at - If this is done, gas sealing with high sealing effect can be achieved over a long period of time. Furthermore, even if a small amount of oil 16 enters the vacuum chamber 2, the oil j6 has a low vapor pressure and will not change into a gas phase, making it possible to maintain the vacuum chamber 2 at a high vacuum and clean. can.

FIG. 2 is a sectional view showing another embodiment, and in this figure, the same or equivalent members as those shown in FIG.

In this embodiment, in order to further enhance the sealing effect, a second seal case 31 is interposed between the seal case 11 and the housing 1 in parallel with the seal case 11 in the axial direction. This second seal case 31 is formed in the shape of the seal case 11 without the outer concave portion 15, and has a second seal chamber 32 sealed with oil 16 on the outside, and a rotary shaft seal member 33 on the inside. A mounted recess 34 is provided and is attached to the housing 1 with a flange 35. 36 is a fixing ring made of an O-ring or the like, and is attached to the housing 12 rotating shaft sealing member 33. The space between the second seal cases 31 is sealed.

In the rotary shaft seal structure of the vacuum device configured in this way, the sealing portions using the oil 16 can be increased to two locations, and the number of sealing locations using the rotary shaft sealing member can be increased to three locations, so that the sealing effect can be further enhanced. can.

In addition, if a higher sealing effect is required, use oil 1.
6 and the rotary shaft sealing member can be further increased, and by increasing the sealing parts in this way, the sealing effect can be further enhanced.

〔Effect of the invention〕

As explained above, according to the present invention, a seal chamber in which a rotary shaft is inserted through the vacuum chamber and low vapor pressure oil is sealed is provided outside the vacuum chamber, and a seal chamber between the seal chamber and the rotary shaft is provided on both sides of the seal chamber. Since the rotary shaft seal member for sealing is provided, the oil in the seal chamber can prevent the atmosphere from entering the vacuum chamber, and the rotary shaft seal member can also prevent this oil from leaking from the seal chamber.

Therefore, compared to the conventional structure in which gas is directly sealed by the rotary shaft sealing member, the gas sealing effect can be enhanced, and atmospheric air can be more reliably prevented from entering the vacuum chamber. Furthermore, since oil with low vapor pressure is used, even if a small amount of oil leaks into the vacuum chamber, the vacuum chamber can be maintained at a high vacuum and clean.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a rotary shaft seal structure of a vacuum device according to the present invention, FIG. 2 is a sectional view showing another embodiment, and FIG. 3 is a sectional view showing a rotary shaft seal structure of a conventional vacuum device. It is. 2...Vacuum chamber, 3...Rotating shaft, 4...Atmosphere, 13...Seal chamber, 16. ...Oil, 21.
22. ... Rotating shaft seal member.

Claims (1)

[Claims] In a vacuum device equipped with a rotating shaft with one end facing into the vacuum chamber and the other end protruding into the atmosphere, a seal chamber in which the rotating shaft is inserted and filled with low vapor pressure oil is provided outside the vacuum chamber,
A rotary shaft seal structure for a vacuum device, characterized in that rotary shaft seal members for sealing between the seal chamber and the rotary shaft are provided on both sides of the seal chamber.