JP2004293639A - Axis sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axis sealing device capable of reducing the amount of leaked operating gas without contacting a rotating shaft. <P>SOLUTION: An axis sealing device 1 comprises a pressurized gas guiding path 30 that comprises an open end 2 which faces an axis sealing space 21 within a casing 11 in which a rotating shaft 16 is positioned; an O ring 3 which is inserted in the inner wall of the casing 11 forming the axis sealing space 21 on both sides of the open end 2; and a cylindrical body 4 that is inserted in the inner wall, for play, through a minute gap outside the rotating shaft 16, to tightly contact the inside of the O ring 3 while allows flowing of the gas from the open end 2 to the outer peripheral part of the rotating shaft 16. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-contact type shaft sealing device.
[0002]
[Prior art]
Conventionally, a non-contact type shaft sealing device is known (for example, see Non-Patent Document 1).
[0003]
[Non-patent document 1]
Kazuo Komotori, Non-contact Seal Theory, Corona Co., Ltd., December 20, 1973, p. 245-255
[0004]
Taking the screw compressor SC shown in FIGS. 2 and 3 as an example, the screw compressor SC has a screw rotor 12 in a casing 11, and is rotatably supported by a bearing 13 on the suction side of the screw rotor 12. A rotating shaft 14 extends, and a rotating shaft 16 rotatably supported by a bearing 15 extends on the discharge side. In the shaft sealing space 17 between the screw rotor 12 and the bearing 13, a labyrinth seal 18 is inserted on the screw rotor 12 side, and a visco seal 19 is inserted on the bearing 13 side. In the shaft sealing space 21, a labyrinth seal 22 is fitted on the screw rotor 12 side, and a visco seal 23 is fitted on the bearing 15 side.
[0005]
Lubricating oil is supplied to the bearings 13 and 15 by oil supply passages 24 and 25. Screws are formed on the inner surfaces of the visco-seals 19 and 23, and a pump action is produced by gas viscosity generated between the shafts 14 and 16 rotating at high speed. The gas sucked from the gas introduction paths 28 and 29 is pushed toward the bearings 13 and 15 to prevent leakage of the lubricating oil.
On the other hand, a small gap (for example, about 20 μm to 30 μm) is maintained between the labyrinth seal 18 and the rotating shaft 14 and between the labyrinth seal 22 and the rotating shaft 16, and the screw rotor 12 side filled with the pressurized gas is maintained. The amount of leaked gas from the fuel cell can be limited. Most of the leaked gas is discharged from the middle of the labyrinth seals 18 and 22 through gas discharge passages 26 and 27, and the remainder is sucked into the visco seals 19 and 23 from the ends of the labyrinth seals 18 and 22.
[0006]
[Problems to be solved by the invention]
In the case of the shaft sealing device having the labyrinth structure described above, it is necessary to maintain gaps between the labyrinth seal 18 and the rotating shaft 14, and between the labyrinth seal 23 and the rotating shaft 16, and the smaller the gap, the better. However, while the labyrinth seals 18 and 23 are fixed and immobile, the rotating shaft 14 or 16 vibrates and is deformed by a load. Therefore, if the gap is made too small, the labyrinth seal 18 and the rotating shaft 14 and the labyrinth seal 23 and the rotating shaft 16 come into contact with each other, and at present, the gap has to be increased to such an extent that this contact can be avoided. Therefore, in the case of an oil-free screw compressor, the leakage of working gas from the shaft sealing device reaches 4.5% for a medium-sized machine and 10 to 15% for a small-sized machine, which increases the compressor performance. There is a problem that it is greatly reduced.
An object of the present invention is to eliminate such a conventional problem, and an object of the present invention is to provide a shaft sealing device capable of reducing a leakage amount of a working gas without contacting a rotating shaft. .
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first invention is to provide a pressurized gas introduction passage having an open end facing a shaft sealing space in a casing in which a rotating shaft is located, and the shaft sealing space on both sides of the opening end. And an O-ring inserted into the inner wall of the casing, which is fitted into the inner wall in a loosely-fitted state outside the rotary shaft via a small gap, closely adheres to the inside of the O-ring, and And a cylindrical main body that allows gas to flow from the end to the outer periphery of the rotating shaft.
[0008]
According to a second aspect of the invention, in addition to the configuration of the first aspect, the cylindrical body has an outer cylinder having a through-hole communicating with the opening end, and an inner cylinder made of a gas-permeable material fitted into the outer cylinder. And a configuration consisting of:
[0009]
According to a third aspect, in addition to the configuration of the second aspect, the outer cylinder is made of a metal material, and the inner cylinder is made of a porous material.
[0010]
In a fourth aspect, in addition to the configuration of the third aspect, the outer cylinder is made of AL and the inner cylinder is made of porous carbon.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an example in which a shaft sealing device 1 according to the present invention is applied to the above-described screw compressor SC. Portions common to those in the configuration shown in FIG.
In the shaft sealing device 1, the O-ring 3 is fitted on the inner wall of the casing 11 forming the shaft sealing space 21 on both sides of the open end 2 of the pressurized gas introduction path 30 to the shaft sealing space 21. In addition, the tubular main body 4 is fitted into the inner wall in a loosely fitted state on the outside of the rotary shaft 16 via a minute gap, and is in close contact with the inside of the O-ring 3. The cylindrical main body 4 includes an outer cylinder 5 made of a metal material, for example, AL, and an inner cylinder 6 made of a porous material, for example, porous carbon. A through-hole 7 for guiding the pressurized gas to the outer periphery of the inner cylinder 6 is provided. Accordingly, the pressurized gas from the open end 2 passes through the through-hole 7, passes through the inner cylinder 6, and fills the minute gap between the inner cylinder 6 and the rotating shaft 16 while maintaining a state filled with the pressurized gas discharge passage 31. It is discharged from.
[0012]
In the shaft sealing device 1 having the above-described configuration, the O-ring 3 is not fixed to the fixed position in the shaft sealing space 21 in an immovable state. It is possible to move as far as possible. In other words, the cylindrical main body 4 of the shaft sealing device 1 has a floating structure, so that even if the rotating shaft 16 is deformed by vibration or load, contact with the rotating shaft 16 is avoided, and the pressurized gas The leakage of the working gas or the working liquid from the minute gap filled with is also prevented. As a result, the performance of the machine using the shaft sealing device 1 can be improved.
[0013]
In the above description, an example in which the shaft sealing device 1 is applied to the shaft sealing space 21 between the screw rotor 12 and the bearing 15 has been described. However, the present invention is not limited to this. It goes without saying that the present invention can be applied to the shaft sealing space 17 between the screw rotor 12 and the bearing 13.
[0014]
Further, the cylindrical main body 4 in the shaft sealing device 1 is not limited to the above-described configuration, and does not necessarily have to have a double cylindrical structure. Any material may be used as long as it can transmit gas and can guide the pressurized gas from the opening end 2 to the outer peripheral portion of the rotating shaft.
Furthermore, the present invention is not necessarily limited to the screw compressor alone, but can be applied to all machines that need to prevent leakage of working gas from the outer periphery of the rotary shaft.
[0015]
【The invention's effect】
As is clear from the above description, according to the first invention, the pressurized gas introduction path having an open end facing the shaft sealing space in the casing where the rotating shaft is located, An O-ring that is inserted into the inner wall of the casing that forms a shaft-sealed space, and is fitted into the inner wall in a loosely-fitted state outside the rotary shaft through a small gap, and is closely attached to the inside of the O-ring; Further, it is configured to include a cylindrical main body that allows a gas flow from the opening end to the outer peripheral portion of the rotating shaft.
[0016]
According to the second invention, in addition to the configuration of the first invention, the tubular body has an outer cylinder having a through-hole communicating with the opening end, and is fitted into the outer cylinder to form a gas-permeable material. And an inner cylinder made of
[0017]
Further, according to the third invention, in addition to the structure of the second invention, the outer cylinder is made of a metal material, and the inner cylinder is made of a porous material.
[0018]
Further, according to the fourth invention, in addition to the structure of the third invention, the outer cylinder is made of AL and the inner cylinder is made of porous carbon.
[0019]
In this manner, the cylindrical body is not fixed in the shaft-sealed space but is movably supported within the range of elastic deformation of the O-ring, and furthermore, between the cylindrical body and the rotating shaft. The pressurized gas is always supplied, a minute gap is maintained, and even if the rotating shaft is deformed due to vibration or load, contact between the cylindrical body and the rotating shaft is avoided, and operation along the outer periphery of the rotating shaft Leakage of gas is prevented, and there is an effect that the performance of a machine to which the shaft sealing device according to the present invention is applied can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a shaft sealing device according to the present invention.
FIG. 2 is a sectional view showing a conventional screw compressor.
FIG. 3 is a partially enlarged sectional view showing a shaft sealing portion on a discharge side in the screw compressor shown in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft sealing device 2 Open end 3 O-ring 4 Cylindrical main body 5 Outer cylinder 6 Inner cylinder 7 Through hole 11 Casing 12 Screw rotor 13 Bearing 14 Rotating shaft 15 Bearing 16 Rotating shaft 17 Shaft sealing space 18 Labyrinth seal 19 Visco seal 21 Shaft Sealed space 22 Labyrinth seal 23 Visco seal 24, 25 Oil supply path 26, 27 Gas discharge path 28, 29 Gas introduction path 30 Pressurized gas introduction path 31 Pressurized gas discharge path SC Screw compressor

Claims (4)

A pressurized gas introduction path having an open end facing the shaft sealing space in the casing where the rotation shaft is located, and O fitted on the inner wall of the casing forming the shaft sealing space on both sides of the opening end. A gas flow from the ring to the outer periphery of the rotary shaft, which is loosely fitted into the inner wall through a minute gap outside the rotary shaft, closely adheres to the inside of the O-ring, and from the opening end to the outer peripheral portion of the rotary shaft. A shaft sealing device comprising: a cylindrical main body that allows pressure. 2. The cylindrical body according to claim 1, wherein the cylindrical body includes an outer cylinder having a through-hole communicating with the opening end, and an inner cylinder fitted into the outer cylinder and made of a gas-permeable material. Shaft sealing device. The shaft sealing device according to claim 2, wherein the outer cylinder is made of a metal material, and the inner cylinder is made of a porous material. The shaft sealing device according to claim 3, wherein the outer cylinder is made of AL, and the inner cylinder is made of porous carbon.

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