JP3305196B2 - Shaft sealing device - Google Patents

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 applied to a centrifugal compressor, other high-speed turbo machines, and the like.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view of a conventional shaft sealing device used particularly in an oil-free environment for a centrifugal compressor and other high-speed turbo machines. In the figure, a seal ring 01 is arranged around a rotating shaft 06 with a gap therebetween, and fitted in a circumferential groove inside the casing 08. The seal ring 01 is generally divided into two or more parts, and as a pressurized spring mechanism, in order to hold the seal ring 01 together and lightly press the seal ring 01 against the wall surface in the circumferential groove to stabilize the position. A garter spring 03 of a helical spring is mounted on one side of the seal ring 01 near the outer periphery. In order to prevent the seal ring 01 from rotating, a detent pin 02 is used.
When a liquid is sealed by such a shaft sealing device, a relatively large pressure acts on the seal ring 01, so that the seal ring 01 is molded integrally, or is firmly connected with bolts or the like to form a garter spring. 03 is not used. Also, when sealing the gas, purge gas supply hole
From 07 , an inert gas having a higher pressure than the gas inside the device to be sealed is supplied to prevent the gas inside the device from leaking out of the device.

[0003] Japanese Patent Application Laid-Open No. 7-71621 discloses a shaft sealing device having a floating seal ring.
This shaft sealing device precisely limits the gap between the seal ring and the rotating shaft, the gap between the seal housing, etc., and uses a stepped rotating shaft to reduce the thrust force due to the gas pressure applied to both ends of the seal ring to seal. The ring is adapted to float substantially.

[0004]

In the conventional shaft sealing device as described above, when the former shaft sealing device is used for sealing a gas, the seal ring 01 is pressed to the low pressure side by a differential pressure between its side surfaces. At the same time, a slight pressing load is applied to the garter spring 03 due to an axial compressive load. When the position of the rotating shaft 06 is displaced, the seal ring 0
Although a gas film pressure is generated between the inner peripheral surface of No. 1 and the outer peripheral surface of the rotating shaft 06 by the action of the hydrodynamic gas bearing, contact is avoided,
If the load capacity of the dynamic pressure gas bearing cannot overcome the product of the pressing load acting in the axial direction and the coefficient of friction, the seal ring 01 and the rotating shaft 06 come into contact with each other,
The wear of the seal ring 01 deteriorates the sealing performance, and thus has a disadvantage that it is difficult to apply to high-speed and high-pressure shaft sealing.
Further, in the shaft sealing device disclosed in Japanese Patent Application Laid-Open No. 7-71621, a thick rotating shaft is required on the high pressure side. It is difficult to apply to a centrifugal compressor having an impeller.

[0005]

Shaft sealing apparatus according to the present invention SUMMARY OF THE INVENTION is the purpose of solving the above problems, a rotating shaft, a seal ring is fitted on the outer periphery of the rotating shaft, of the sealing ring
Low pressure side of the seal ring to limit axial movement
A seal housing having an end surface loosely fitted therein, and
And have you the shaft seal device for a shaft sealing a sealing fluid by labyrinth interposed between the said sealing ring, the first circumferential provided on the sliding surface in the axial direction of the said sealing ring and said sheet Lumpur housing Groove and the rotation axis surface of the seal ring.
A third circumferential groove opening toward the labyrinth;
A second circle opened on the rotating shaft surface between the circumferential groove and the third circumferential groove
A circumferential groove is provided to communicate the first circumferential groove and the third circumferential groove.
Supplying a purge gas to the third circumferential groove through a narrow hole
And the second circumferential groove communicates with the outside through an exhaust passage.
A shaft sealing device is provided . Shi Ruringu is subjected to pressure of the sealing fluid to the end face opposite to the first circumferential groove, but the seal ring results in a reaction force to the high pressure side by electrostatic pressure effect of the purge gas supplied to the first circumferential groove, The surface pressure of the sliding contact surface around the first circumferential groove is reduced, and the frictional force caused by the sliding contact is reduced. As a result, the resistance of the seal ring to radial movement is reduced, and the seal ring and the rotating shaft can be easily moved by the reaction force of the lubricating film formed by the fluid formed between the inner peripheral surface of the seal ring and the outer peripheral surface of the rotating shaft. Are easily separated from each other. Also, in the third circumferential groove that opens toward the labyrinth
Is supplied with a purge gas from the first circumferential groove through a fine hole.
Therefore, the seal fluid reduces the labyrinth on the inner circumference of the seal ring.
It can be prevented from passing through to the low pressure side.
Further, the second axial groove is provided between the first circumferential groove and the third circumferential groove.
A circumferential groove is opened, and the second circumferential groove is opened through an exhaust passage.
Since it is communicated to the outside, as described above, the third circumferential groove
Most of the purge gas supplied to the second circumferential groove is exhausted from the second circumferential groove.
Will be issued . The present invention also relates to the shaft sealing device described above.
The purge gas supplied to the first circumferential groove is supplied to the seal flow.
It has a slightly higher pressure than the body . The seal fluid tends to flow to the low pressure side through the labyrinth on the inner circumference of the seal ring, but slightly higher than the seal fluid as described above.
Supplying a purge gas having had pressure to the first circumferential groove
Thus , the pressure difference between the inside and the outside of the labyrinth can be kept small by supplying the purge gas having a pressure slightly higher than the seal fluid into the third circumferential groove.
Moreover, the force static pressure within the first circumferential groove in which the sealing fluid by purge gas slightly pressure than the seal fluid is supplied to the first circumferential groove of the sliding surface presses the seal ring into sliding contact surface To reduce. Incidentally, assures movement in the radial direction of the seal ring, to prevent the purge gas from leaking to the outside of the circumferential groove, physicians use a spring mechanism to provide a preload to the seal ring
You .

[0006]

FIG. 1 is an explanatory view of a shaft sealing device according to an embodiment of the present invention. In the figure, the shaft sealing device according to the present embodiment is used particularly in an oil-free environment for a centrifugal compressor, other high-speed turbomachines, etc., and as shown in FIG. Circumferential groove 1
8 are provided, and two second circumferential grooves 20 and a third circumferential groove 14 which are not communicated with each other are provided on the inner peripheral surface thereof. First
The circumferential groove closer to the circumferential groove 18 is referred to as a second circumferential groove 20, and the circumferential groove remote from the circumferential groove 18 is referred to as a third circumferential groove 14. The first circumferential groove 18 and the third circumferential groove 14 are communicated with each other through a fine hole 19, and a purge gas having a pressure slightly higher than the high-pressure side seal gas inside the machine is introduced into the first circumferential groove 18. It is supposed to be. An exhaust passage 13 is provided between the second circumferential groove 20 and the outer peripheral surface of the seal ring 1 for communicating the two, and a space is provided between the outer peripheral surface of the seal ring 1 and the inner peripheral surface of the seal housing 4 facing the same. Is provided to allow radial movement of the seal ring 1, the space of which is in communication with the exclusion tower. In order to press the end face provided with the first circumferential groove 18 on the seal ring 1 against the oil drain housing 5 or the seal housing 4 having an end face having a larger inner and outer diameter than the end face inside the seal housing 4, a donut type is used. A diaphragm type preload spring mechanism 3 using a thin disk is provided. A ring-shaped seal piece made of an elastomer is interposed in the inner peripheral portion of the spring mechanism 3 that presses the seal ring 1.
This seal piece can be hermetically connected to the seal ring 1 by welding or the like, or can be brought into contact with the seal ring 1 so as to allow sliding. The seal ring 1 is made of a material such as carbon which is lightweight and hardly undergoes a dimensional change from the viewpoint of followability with the rotating shaft 6, and is disposed at an appropriate gap from the rotating shaft 6. The seal ring 1 is loosely fitted inside the seal housing 4 and is capable of being displaced in the radial direction. In the space on the left side of the seal ring 1 in the drawing, the seal gas pressurized by the compressor wheel 9 leaks through the labyrinth 10 in the radial direction. An oil drain housing 5 is provided on the right side of the seal ring 1, and lubricating oil or the like transmitted on the surface of the rotating shaft 6 is blown off by centrifugal force of the oil drain fins 7, and oil drain passages 25, 26, 27 are provided. After returning to the lubricating oil device.

The seal gas pressurized by the compressor wheel 9 passes through the labyrinth 2 on the inner periphery of the seal ring 1 and the third circumferential groove 1
4, the purge gas having a pressure slightly higher than the seal gas is supplied to the third circumferential groove 14 through the purge gas supply hole 16, the purge gas communication hole 17, the first circumferential groove 18, the fine hole 19, and the like. The flow of the purge gas is divided from the third circumferential groove 14 into two parts: the compressor wheel 9 side and the second circumferential groove 20. By controlling the pressure of the purge gas in conjunction with the pressure of the seal gas on the compressor wheel 9 side to maintain a small differential pressure between the third circumferential groove 14 and the space on the compressor wheel 9 side, Even if the gap is small, the labyrinth seal can be adopted while suppressing heat generation due to viscosity in the labyrinth seal. Second circumferential groove 20
Most of the purge gas supplied to the third circumferential groove 14 is discharged from the second circumferential groove 20 because the purge gas in the inside is guided to the low-pressure exclusion tower through the exhaust passages 13, 12, 11. The purge gas is supplied into the first circumferential groove 18, and the static pressure in the first circumferential groove 18 causes the pressure of the seal gas to press the seal ring 1 from the compressor wheel 9 side to the oil drain housing 5 side. Therefore, the seal ring 1 can easily follow the seal ring 4 in the radial direction in the seal housing 4, and the seal ring 1 and the rotary shaft 6
Can be avoided by the lubricating action of the gas. In addition, by using the spring mechanism 3 for preload, while following the seal ring 1 in the radial direction is guaranteed,
The seal gas is prevented from leaking to the exhaust passage sides 11 and 12.

In the conventional shaft sealing device, when the former shaft sealing device is used for sealing a gas, the seal ring is pressed to a low pressure side by a differential pressure between its side surfaces, and an axial compression load is applied to the garter spring. A small pressing load is applied. When the position of the rotating shaft is displaced, gas film pressure is generated between the inner peripheral surface of the seal ring and the outer peripheral surface of the rotating shaft due to the action of the dynamic pressure gas bearing, thereby avoiding contact.
If the load capacity of the dynamic pressure gas bearing cannot overcome the product of the pressing load acting in the axial direction and the coefficient of friction, the seal ring and the rotating shaft will come into contact with each other, causing the wear of the seal ring and the sealing. There is a disadvantage that it is difficult to apply to high-speed and high-pressure shaft sealing because the performance is deteriorated. Further, in the shaft sealing device disclosed in Japanese Patent Application Laid-Open No. 7-71621, a thick rotating shaft is required on the high pressure side. Although it is difficult to apply to a centrifugal compressor having an impeller, in this shaft sealing device, a cylindrical seal ring 1 provided on the outer periphery of a rotating shaft 6 with a gap therebetween, and axial movement of the seal ring 1 Is formed by a seal housing 4 fitted to the seal ring 1 so as to limit the diameter of the seal ring 1. Second and third circumferential grooves 2
0, 14 and a first circumferential groove 18 on the end face of the seal ring 1.
A small hole 19 is provided for communicating the third circumferential groove 14 provided on the farther side with the first circumferential groove 18 on the end face, and the fine hole 19 provided on the end face of the seal ring 1 on the side closer to the first circumferential groove 18. An exhaust passage 13 communicating between the two circumferential grooves 20 and the outer peripheral surface of the seal ring 1 is provided, and a space is provided between the outer peripheral surface of the seal ring 1 and the inner peripheral surface of the seal housing 4 facing the seal ring 1. In the radial direction, and the space is communicated with the excluded column outside the system. The first circumferential groove 18 on the end face of the seal ring 1 is pressed against the oil drain housing 5 having an end face inside and outside of the seal housing 4 having a larger inner and outer diameter than the end face of the seal housing 4, and the first circumferential groove 18 on the end face of the seal ring 1. A purge gas is introduced from the outside into a space generated between the groove 18 and the pressed end surface of the seal housing 4,
The first circumferential groove 18 on the end face of the seal ring 1 exists on the low pressure side, and the seal ring 1 reduces the pressure of the seal gas to the first circumferential groove 1.
8, the pressure introduced into the first circumferential groove 18 is higher than the seal gas by the static pressure of the purge gas, so that the seal ring 1 generates a pressure to the high pressure side, and The surface pressure of the contact portion inside and outside the peripheral groove 18 is reduced, and the frictional force caused by this surface pressure is suppressed to a small value. Thereby, the resistance to the radial movement of the seal ring 1 is reduced, and the seal ring 1 can be easily formed by the reaction force of the gas lubricating film formed between the inner peripheral surface of the seal ring 1 and the outer peripheral surface of the rotating shaft 6. And the rotating shaft 6 are easily separated from each other. Second circumferential groove 20
Communicates with the space formed by the outer peripheral surface of the seal ring 1, the seal housing 4 and the spring mechanism 3 and the exhaust passages 11, 12 via the exhaust passage 13, and from the first circumferential groove 18 through the fine holes 19. When a part of the purge gas that has performed the sealing action in the three circumferential grooves 14 and the seal piece of the preload spring mechanism 3 are of a contact type, a slight gap is formed from the gap between the seal piece and the seal ring 1 into this space. It is a passage leading the sealing gas leaking to the exclusion tower. Thus, the non-contact seal ring 1 can be easily formed in the peripheral surface type shaft sealing device, and an inexpensive dry gas sealing system can be provided.

[0009]

Shaft sealing apparatus according to the present invention is constituted as described above, although sealing fluid tries to flow to the low pressure side through the labyrinth inner periphery of the seal ring, a labyrinth Distance
In the third circumferential groove, the purge gas, especially the seal fluid ,
Since the pressure difference between the inside and outside of the labyrinth can be kept small by supplying the purge gas having a slightly high pressure, a labyrinth seal can be applied, and the heat generated due to the viscosity in the gap due to the small gap. Can be suppressed. Further, since the purge gas static pressure inside the first circumferential groove by being supplied to the first circumferential groove of the sliding contact surface reduces the force that seals the fluid presses the seal ring into sliding contact surface, the seal ring Can easily follow the radial direction inside the seal housing, and the contact between the seal ring and the rotating shaft caused by vibration or displacement of the rotating shaft is avoided by the lubricating action of the fluid.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a shaft sealing device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional shaft sealing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seal ring 2 Labyrinth 3 Spring mechanism 4 Seal housing 5 Oil drain housing 6 Rotating shaft 7 Oil drain fin 8 Casing 9 Compressor impeller 10 Labyrinth 11 Exhaust passage 12 Exhaust passage 13 Exhaust passage 14 Third circumferential groove 15 O-ring 16 Purge gas supply hole 17 Purge gas communication hole 18 First circumferential groove 19 Fine hole 20 Second circumferential groove 21 O-ring 22 O-ring 23 O-ring 24 O-ring 25 Oil drain passage 26 Oil drain passage 27 Oil drain passage

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16J 15/34-15/38 F16J 15/40-15/453 F16J 15/54-15/56

Claims (2)

(57) [Claims] Limitations and 1. A rotary shaft, a seal ring is fitted on the outer periphery of the rotary shaft, the axial movement of the seal ring
The seal with the low-pressure end face of the seal ring loosely fitted
A rotary housing and the seal ring.
The first circumferential groove in the shaft sealing device for shaft-sealing the sealing fluid by interposed labyrinth, provided on the sliding surface in the axial direction of the said sealing ring and said sheet Lumpur housing between
And the above-mentioned labyrinth on the rotation axis surface of the seal ring
A third circumferential groove opened in the first, the first circumferential groove and the third circumferential groove
And a second circumferential groove opened on the rotation shaft surface between
The above-mentioned via a fine hole communicating the first circumferential groove and the third circumferential groove.
A purge gas is supplied to the third circumferential groove and the second circular groove is supplied.
A shaft sealing device wherein the circumferential groove communicates with the outside via an exhaust passage . 2. The method according to claim 1, wherein the first circumferential groove has
Supply purge gas at a slightly higher pressure than the sealing fluid
At the same time, the seal ring and the seal housing
Characterized by having a spring mechanism to press against the contact surface of
Shaft sealing device .