JPH05302676A - Shaft sealing device for vertical rotary machine - Google Patents

Abstract

PURPOSE:To provide a long-reliable/maintenance-free shaft sealing device by which oil vapor generated in an oil lubricating bearing part can be prevented completely from leaking outside of a bearing housing from seal clearance of labyrinth seals. CONSTITUTION:A magnetic fluid seal device 23 composed of magnetic path taces 27 and 28, magnetic fluid 29 and a permanent magnet 26 is incorporated between an upper labyrinth seal 22 and a lower labyrinth seal 24. A means to supply purge gas and a means to water-cool the back faces of the magnetic path taces 27 and 28 are also arranged in chamber parts 22b and 24b of the respective labyrinth seals 22 and 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal device for preventing oil vapor generated in a bearing portion of a vertical rotary machine from leaking from a seal portion.

[0002]

2. Description of the Related Art In recent years, as the control of environmental pollution in each technical field becomes severe, it is necessary to take measures to prevent leakage of oil vapor of oil-lubricated bearings of various rotary machines. Machines (such as induction motors) have strong demands for long-term reliability and maintenance-free.

The leakage of oil vapor from the bearing portion is
The bearing performance may be deteriorated due to the reduction of the amount of lubricant in the bearing housing, and the leakage of oil vapor into the machine may cause the dielectric breakdown due to the deterioration of the insulation such as the coil coating, which may be the main cause of the accident. .. Next, referring to typical examples of the prior art, the phenomenon of oil vapor leakage will be described in detail with reference to FIGS.

This prior art shows an induction motor installed in a nuclear power plant as a typical example of a vertical rotary machine. A thrust collar 2 is fitted and fixed to a lower end shaft portion of a rotary shaft 1, and this thrust collar is used. Thrust pad bearing 3 consisting of several sectors rotatably supporting the collar underneath
Then, a pad support base 5 for supporting the thrust pad bearing 3 via an elastic body 4 such as a coil spring is arranged.

A guide bearing 6 is arranged on the outer circumference of the thrust collar 2, and the guide bearing 6 is a bearing housing 7.
It is fixed to. The bearing housing 7 has an annular inner wall 8 surrounding the lower end shaft portion of the rotary shaft 1, and a labyrinth seal 9 is installed above the guide bearing 6 at the upper part of the housing.

A lubricant 11 is enclosed in the housing 7, and a cooling pipe 1 for cooling the lubricant 11 is provided.
0 is disposed inside the housing 7. The bearing housing 7 is firmly fixed to the foundation floor 13 by the support ribs 12. An air vent pipe 18 is connected to the upper part of the housing, and a filter 19 is provided at the end of the air vent pipe 18. Has been.

A rotor 14 composed of a rotor core 14a and a rotor coil 14b is fitted and fixed to the rotary shaft 1,
A stator frame 15 surrounding the rotary shaft 1 has a stator 1 including a stator core 16a and a stator coil 16b.
6 are fitted and fixed, and several cooling fans 17 are attached to the lower outer peripheral portion of the stator frame 15. Next, the operation of the above configuration will be described.

When the rotary shaft 1 rotates, the rotary shaft 1
Due to the viscous stirring effect of the lubricant 11 by the bottom sliding surface 2a of the thrust collar 2 attached to the, a vigorous circulating flow of the lubricant 11 as shown by arrow A in FIG. 4 is generated.

In the self-pump hole 2b formed in the thrust collar 2, the lubricant 11 is supplied to the guide bearing 6 by the centrifugal pump action of this hole, and the annular groove 6a provided in the guide bearing 6 and several holes. 4 is circulated through the vertical groove 6b and the oil passage 7a of the bearing housing 7 as shown by an arrow B in FIG. In particular, the lubricant 1 discharged from the guide bearing 6
1 entrains a large amount of air and is returned into the bearing housing 7.

In such a circulating flow of the lubricant 11, since the bearing loss of the thrust pad bearing 3 and the guide bearing 6 and the agitation loss due to the thrust collar 2 become large, the temperature of the lubricant 11 inside the bearing housing 7 becomes high. .. As a result, oil vapor is generated from the lubricant 11 and the internal pressure of the bearing housing 7 increases.

The oil vapor is discharged from the vent pipe 18 through a filter 19, which is
Separates the passing oil vapor into air and lubricant 11,
Only the air is discharged to the outside and the separated lubricant 11 is collected.

However, if a filter 19 having a fine mesh is applied here, the pressure loss becomes large and the internal pressure of the bearing housing 7 becomes high. On the contrary, the filter 19 having a coarse mesh reduces the amount of the lubricant 11 collected. Therefore, the filter 19 having an appropriate mesh roughness is selected, and the internal pressure of the bearing housing 7 is slightly increased (actually, several hundred mmaq).

On the other hand, cool air is sent into the machine by the cooling fan 17, and the average pressure in the machine becomes considerably high. However, in the upper space of the labyrinth seal 9, an air flow as shown by an arrow C in FIG. 4 is generated by the centrifugal fan action of the shaft end surface 1a of the rotary shaft 1, so that the pressure at the upper end position of the labyrinth seal 9 is a negative pressure. become.

Further, in the case of a vertical rotary machine, the whirling of the rotary shaft 1 may be about the bearing clearance 20 of the guide bearing 6, so that the seal clearance 2 of the labyrinth seal 9 is provided.
1 is larger than the bearing gap 20. Further, a lubricating film is formed in the bearing gap 20 by the dynamic action of the thrust collar 2, and a fluid film pressure as shown in FIGS. 6 and 7 is generated. That is, FIG. 6 is a pressure distribution diagram in the circumferential direction when the thrust collar 2 swings around, and FIG. 7 is a pressure distribution diagram in the bearing width direction (a view taken along the line BB in FIG. 6). For this reason, the lubricant 11 is applied to the thrust collar 2 from the end of the bearing width of the guide bearing 6.
It jumps out along the surface of and reaches the labyrinth seal 9 easily.

[0015]

In the shaft sealing device with the labyrinth seal 9 as described in the above-mentioned conventional example, the oil vapor generated in the oil lubricated bearing portion is exposed from the seal gap 21 of the labyrinth seal 9 to the outside of the bearing housing 7 (the above-mentioned In the conventional example, it leaks to the machine and the lubricant 11 in the bearing housing 7
However, there is a problem that the bearing performance is deteriorated due to the decrease of the oil amount, and there is a problem of environmental pollution due to the leakage of the oil vapor out of the machine. In particular, when the shaft sealing device is applied to the above-described conventional vertical rotary machine (induction motor), the oil vapor leaking inside the machine causes the rotor coil 14b and the stator coil 1 to leak.
There is a problem that the insulator 6b is deteriorated and causes problems such as dielectric breakdown.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to completely prevent the oil vapor generated in the oil lubricated bearing portion from leaking out of the bearing housing through the seal gap of the labyrinth seal. (EN) Provided is a long-term reliable and maintenance-free shaft sealing device.

[0017]

In order to achieve the above-mentioned object, a shaft sealing device in a vertical rotary machine of the present invention comprises a magnetic path tooth, a magnetic fluid and a permanent magnet between a top labyrinth seal and a bottom labyrinth seal. A magnetic fluid sealing device including a magnet is incorporated, and means for supplying a purge gas to the chamber portion of each labyrinth seal and means for cooling the back surface of the magnetic path teeth with water are provided.

[0018]

In the magnetic fluid seal device including the magnetic path teeth, the magnetic fluid, and the permanent magnet, the magnetic fluid is brought into close contact with the magnetic path teeth by the magnetic circuit formed by the permanent magnets, and the gap between the rotating shaft and the magnetic path teeth is formed. Since the sealing is performed with the magnetic fluid, the sealing property is perfect, and it is possible to completely prevent the oil vapor generated in the oil lubricated bearing portion from leaking to the outside of the bearing housing through the gap.

Further, by supplying a purge gas to the chamber portions of the upper labyrinth seal and the lower labyrinth seal, it is possible to prevent deterioration of the sealing performance of the magnetic fluid due to the mixing of the oil vapor with the magnetic fluid, and the upper and lower portions of the magnetic fluid sealing device. It is possible to minimize the differential pressure at. Further, by cooling the back surface of the magnetic path teeth with water, the temperature rise of the magnetic path teeth can be suppressed and evaporation of the magnetic fluid can be prevented, so that long-term reliability can be improved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. The same parts as those of the conventional technique described with reference to FIGS. 4 to 6 are designated by the same reference numerals and the description thereof will be omitted.

The Y portion (FIG. 2) of FIG. 1 corresponds to the X portion (labyrinth seal portion shown in FIG. 5) shown in the prior art of FIG. 4, and the construction of this portion, that is, the construction of the shaft sealing device of the present invention. As shown in FIGS. 2 and 3, includes an upper labyrinth seal 22, a magnetic fluid sealing device 23, and a lower labyrinth seal 24, which are arranged and fixed in a seal casing 25 made of a non-magnetic material as shown in FIG. It

The upper labyrinth seal 22 has a labyrinth portion 22a located on the upper side and a chamber portion 22b located on the magnetic fluid sealing device 23 side, and the lower labyrinth seal 24 has a labyrinth portion 24a located on the lower side and a magnetic fluid. Chamber part 24b located on the sealing device 23 side
Have and.

The magnetic fluid sealing device 23 is incorporated between the upper labyrinth seal 22 and the lower labyrinth seal 24, and its construction is composed of several permanent magnets 26 arranged on the circumference and the permanent magnets 26. A pair of upper and lower magnetic path teeth 27 and 28 arranged so as to be sandwiched, and the rotary shaft 1 and the magnetic path teeth 2 are closely attached to the tips of the upper and lower magnetic path teeth 27 and 28.
And a magnetic fluid 29 that seals the gap between them and.

On the outer peripheral surfaces of the magnetic path teeth 27 and 28,
Water-cooled circumferential grooves 27a, 28a and O-ring grooves 27b, 28b
Are processed and formed, and O is formed in the O-ring grooves 27b and 28b.
The ring 30 is installed.

A water supply groove 25a and a drain groove 25b intersecting with the water-cooled circumferential grooves 27a, 28a are formed in the seal casing 25. The water supply groove 25a and the drain groove 2 are formed.
A water supply hole 25c and a drain groove 25d communicate with 5b.
The water supply pipe 31 is provided in the water supply hole 25c.
Is connected via a flow rate adjusting valve 32, and a water distribution pipe (not shown) is connected to the drain groove 25d.

In the labyrinth seals 22 and 24 and the seal casing 25, there are purge gas introduction holes 22c which are open to communicate with the chamber portion 22b of the upper labyrinth seal 22 and the chamber portion 24b of the lower labyrinth seal 24.
24c and 25e are provided, and the seal casing 25
A purge gas introducing pipe 33 is connected to the purge gas introducing hole 25e, the tip of which is located in the vicinity of the outlet of the cooling fan 17, and the air collecting device 34 is installed therein.

Next, the operation will be described. In the magnetic fluid seal device 23 including the magnetic path teeth 27, 28, the magnetic fluid 29, and the permanent magnet 26, the permanent magnet 26 causes the magnetic circuit 35 as shown by the chain line in FIG.

Therefore, the magnetic fluid 29 adheres to the magnetic path teeth 27 and 28 by the magnetic circuit 35 formed by the permanent magnet 26, and a strong magnetic fluid film is formed between the rotary shaft 1 and the magnetic path teeth 27 and 28. Form and maintain perfect sealing function.

It is known that when the magnetic fluid 29 is mixed with a different medium such as the lubricant 11, the sealing function of the magnetic fluid 29 is deteriorated. Therefore, in the present invention, the chambers 22b and 24b of the upper labyrinth seal 22 and the lower labyrinth seal 24 are supplied with air having a higher pressure than the air collecting device 34 provided at the outlet of the cooling fan 17 through the purge gas introducing pipe 33. To do. Part of this air (purge gas) is supplied into the bearing housing 7 through the labyrinth portion 24 a of the lower labyrinth seal 24.
The oil vapor generated in the bearing housing 7 is the magnetic fluid 2
Does not reach position 9.

On the other hand, part of the air (purge gas) supplied from the air collecting device 34 is also supplied to the chamber portion 22b of the upper labyrinth seal 22, passes through the labyrinth portion 22a of the upper labyrinth seal 22, and is discharged into the machine. It Therefore, the pressure difference between the upper and lower portions of the magnetic fluid sealing device 23 is extremely small, the sealing function of the magnetic fluid 29 becomes very easy, and the introduction of the purge gas cools the magnetic fluid sealing device 23. In addition, magnetic path teeth 2
By cooling the back of 7, 28 with water,
The temperatures of 7, 28 and the magnetic fluid 29 are lowered,
9 can be prevented from evaporating, which is extremely effective for long-term reliability.

[0031]

According to the shaft sealing device of the present invention, the oil vapor generated in the oil-lubricated bearing portion can be perfectly sealed in a wide range of low speed and high speed regions. It is possible to provide a vertical rotary machine that has improved long-term reliability and is maintenance-free, and that has high performance and long-term reliability because the problems of deterioration of bearing performance and environmental pollution are improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing a shaft sealing device for a vertical rotary machine according to an embodiment of the present invention.

FIG. 2 is a detailed view of a main part showing an enlarged part Y of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a longitudinal sectional view of a main part showing a shaft sealing device in a conventional vertical rotary machine.

5 is a detailed view showing an enlarged part X of FIG.

FIG. 6 is a principle diagram for explaining a problem of the conventional technique.

FIG. 7 is a view on arrow BB in FIG.

[Explanation of symbols]

 1 rotating shaft 2 thrust collar 3 thrust pad bearing 5 pad support 6 guide bearing 7 bearing housing 11 lubricant 14 rotor 15 stator frame 16 stator 22 upper labyrinth seal 23 magnetic fluid seal device 24 lower labyrinth seal 22a, 24a upper and lower labyrinth Seal labyrinth portion 22b, 24b Chamber portion 22c, 24c Purge gas introduction hole 25 Seal casing 25a Water supply groove 25c Water supply hole 25d Drain groove 25e Purge gas introduction hole 26 Permanent magnet 27, 28 Magnetic path teeth 27a, 28a Water-cooled circumferential groove 29 Magnetic fluid 31 Water absorption pipe 33 Purge gas introduction pipe 34 Air collecting device

Claims (1)

[Claims] 1. A means for incorporating a magnetic fluid seal device including a magnetic path tooth, a magnetic fluid and a permanent magnet between the upper labyrinth seal and the lower labyrinth seal, and means for supplying a purge gas to the chamber portion of each labyrinth seal, A shaft sealing device for a vertical rotating machine, characterized in that it is provided with means for cooling the back surface of the magnetic path texture with water.