JPH08159293A - Shaft sealing device - Google Patents

Abstract

PURPOSE: To prevent the occurrence of shock crack and breakage owing to a difference in a level between the adjoining seal ring pieces of a seal ring on the rotation side and a seal ring on the static side. CONSTITUTION: A seal ring 26 on the rotation side consists of a plurality of seal ring pieces 26a peripherally arranged in an adjoining state and a seal ring 25 on the static side is attached to a seal case 9 in such a state to be brought into pressure contact with the seal ring 26 on the rotation side. The seal ring pieces 26a of the seal ring 26 on the rotation side are formed of a ceramics material and meanwhile the seal surface of the seal ring 25 on the static side is coated with a hard metal 28.

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, and more particularly to a shaft sealing device for preventing water leakage from a rotary shaft of a hydraulic machine such as a water turbine or a pump turbine.

[0002]

2. Description of the Related Art Generally, a hydraulic machine such as a water turbine or a pump turbine is provided with a shaft seal device for preventing pressure water around a runner directly connected to a main shaft from leaking to the outside from the main shaft. An example of this type of shaft seal device is Japanese Patent Laid-Open No.
2-1810703, JP-A-62-237172 and JP-A-62-800773.

8 and 9 show a typical example of the shaft sealing device disclosed in the above publication. As shown in FIG. 8, a flange 2 is projected from the main shaft 1 in the vicinity of the upper portion of the runner directly connected to the main shaft 1 of the hydraulic machine. A rotary seal ring 5 is attached to the flange 2 via a metal ring 3 and an attachment 4.

The housing 6 surrounds the flange 2.
And a seal case 9 is arranged on the inner peripheral side of the housing 6 via a cover 7 and an O-ring 8. A stationary seal ring 12 is attached to the seal case 9 via a metal ring 10 and an attachment 11. A plurality of springs 13 are arranged along the circumferential direction between the cover 7 and the seal case 9,
The spring 13 presses the seal surface 12 a of the stationary seal ring 12 against the seal surface 5 a of the rotary seal ring 5 via the seal case 9.

As shown in FIG. 9, the rotary side seal ring 5 and the stationary side seal ring 12 have seal ring pieces 15 and 22, respectively.
In addition to conventional fired carbon, a ceramic material such as silicon carbide has recently been used as the material.
These seal ring materials are composed of a plurality of seal ring pieces 15 and 22 because of restrictions in manufacturing dimensions.

In the shaft sealing device shown in FIGS. 8 and 9 configured as above, the rotating side seal ring 5, the stationary side seal ring 12 and the O ring 8 prevent leakage of high pressure water on the runner side A. There is.

[0007]

As described above, in the conventional shaft sealing device, the rotary side seal ring 5 and the stationary side seal ring 12 each have a plurality of seal ring pieces 15, 22.
The seal surface 5a of the rotary side seal ring 5 and the seal surface 12 of the stationary side seal ring 12
There is a problem that a is not in the same plane, and a slight step d is likely to occur at the boundary between the adjacent seal ring pieces 15 and 22.

More specifically, as shown in FIG. 9, when there is a step d at the boundary between the adjacent seal ring pieces 15 and 22, when the rotating side seal ring 5 rotates, the boundary portion between the seal ring pieces 15 is rotated. The step d and the step d at the boundary of the seal ring piece 22 collide with each other to give an impact to the rotating side seal ring 5 and the stationary side seal ring 12.

Further, due to the step d, the pressing load distribution of the seal ring pieces 15 and 22 changes with the rotation speed, and becomes a source of vertical vibration. For this reason, impact cracking or chipping of the seal ring pieces 15 and 22 occurs, and the water sealing performance of the shaft sealing device is significantly reduced. In particular, the seal rings 5,1
The second material is remarkable in brittle materials such as calcined carbon and ceramics having poor impact resistance.

In order to eliminate the step d as described above, it is necessary to significantly improve the processing accuracy of the seal ring pieces 15 and 22, the processing accuracy of the flange 2 and the seal case 9, and the mounting accuracy. This causes a problem that the manufacturing cost of the shaft sealing device becomes extremely high.

Further, in order to eliminate the occurrence of the step d at the boundary portion, a method of processing the seal surfaces 5a and 12a with the respective seal ring pieces 15 and 22 fixed to the metal rings 3 and 10 can be considered. .

However, according to this measure, if a part of the seal ring pieces 15, 22 is damaged or defective during operation, the seal ring pieces 15, 22 having the damage or defect are generated.
It is necessary to replace both the metal ring 3 and the metal ring 3 which holds the seal ring, which is extremely uneconomical, and the seal ring pieces 15 and 2 are required to restart the operation of the device early.
Another problem arises in that one set of 2 and the metal rings 3 and 10 must be always prepared as a spare part.

Further, although the spring 13 has a function of absorbing fluctuations in the direction perpendicular to the seal surfaces 5a and 12a which are generated in a normal operating state, the spring 13 has a high level which is generated in a stable rotating state in a transient operating state. It is not possible to follow the minute vibration of the cycle, and the seal ring piece 1 is caused by the impact force of the minute vibration of the high cycle.
There is also a risk that the parts 5 and 22 will be damaged.

Further, since the seal ring pieces enhance the water sealing performance, there is almost no gap between the adjacent seal ring pieces 15 and 22. Therefore, frictional heat is generated on the seal surface as the rotary seal ring 5 rotates, and the frictional heat causes thermal stress in the seal ring pieces 15 and 22 due to thermal expansion in the circumferential direction. This thermal stress may cause thermal cracks in the seal ring pieces 15 and 22. Then, during use for a long period of time, a large amount of foreign matter such as earth and sand mixed in the high-pressure water passes through the seal ring, and the water sealing performance is instantly deteriorated.

The present invention has been made in consideration of the above-mentioned circumstances. A first object of the present invention is to provide an impact crack or a drop due to a step between adjacent seal ring pieces of a rotating side seal ring and a stationary side seal ring. It is to provide a shaft sealing device capable of preventing such a situation.

A second object of the present invention is to equalize the static load distribution of each seal ring piece due to the step between the adjacent seal ring pieces of the rotary side seal ring, and to seal by vertical vibration. An object of the present invention is to provide a shaft sealing device capable of preventing the ring piece from being damaged by impact.

Further, a third object of the present invention is to improve the cooling performance of heat generated by friction generated between the rotary side seal ring and the stationary side seal ring, and to adjoin the rotary side seal ring. An object of the present invention is to provide a shaft sealing device capable of mitigating thermal stress caused by thermal expansion in the circumferential direction between seal ring pieces and preventing thermal cracking.

A fourth object of the present invention is to temporarily lose the sealing function when the rotating side seal ring or the stationary side seal ring loses its water sealing function due to abnormal wear or damage due to a large amount of earth and sand. To provide a shaft sealing device capable of preventing a large amount of leakage.

[0019]

In order to solve the above-mentioned problems, the first aspect of the present invention provides a flange projecting from a rotary shaft, a housing arranged so as to surround the flange, and A seal case arranged in the housing, a rotary side seal ring attached to the flange and having a plurality of seal ring pieces arranged adjacent to each other in the circumferential direction, and the seal case arranged in pressure contact with the rotary side seal ring. In the shaft sealing device provided with the stationary side seal ring attached to, while the sealing ring piece of the rotating side seal ring is made of a ceramic material, the sealing surface of the stationary side seal ring is coated with cemented carbide. Characterize.

According to a second aspect of the present invention, a flange projecting from the rotary shaft, a housing arranged so as to surround the flange, a seal case arranged in the housing, and a plurality of circumferentially mounted flanges are attached to the flange. A shaft sealing device comprising: a rotating-side seal ring in which individual seal ring pieces are arranged adjacent to each other; and a stationary-side seal ring attached to the seal case arranged in pressure contact with the rotating-side seal ring. A plurality of circumferential grooves are formed at a position facing the rotary side seal ring of the flange, and a ring-shaped elastic body is inserted into the circumferential groove, and a high pressure water introduction hole is provided between the plurality of circumferential grooves of the flange. Is provided, and the rotating-side seal ring is held by the high-pressure water pressure from the ring-shaped elastic body and the high-pressure water introduction hole.

According to a third aspect of the present invention, a flange projecting from the rotary shaft, a housing arranged so as to surround the flange, a seal case arranged in the housing, and a plurality of circumferentially mounted flanges are attached to the flange. A shaft sealing device comprising: a rotating-side seal ring in which individual seal ring pieces are arranged adjacent to each other; and a stationary-side seal ring attached to the seal case arranged in pressure contact with the rotating-side seal ring. It is characterized in that a cooling groove is formed between each seal ring piece, and an elastic spacing piece is arranged.

According to a fourth aspect of the present invention, there is provided a flange projecting from the rotary shaft, a housing arranged so as to surround the flange, a seal case arranged in the housing, and a plurality of circumferentially mounted flanges. A shaft sealing device comprising: a rotating-side seal ring in which individual seal ring pieces are arranged adjacent to each other; and a stationary-side seal ring attached to the seal case arranged in pressure contact with the rotating-side seal ring. It is characterized in that a floating shaft sealing device is arranged at the upper end of the seal case.

[0023]

According to the first aspect of the present invention, a seal ring piece made of ceramics having extremely excellent wear resistance is used for the rotary side seal ring, while the stationary side seal ring has a slightly lower wear resistance than the rotary side seal ring. Since the seal surface is coated with, it is possible to prevent collision damage of the step between the seal ring pieces of the conventional rotary side seal ring and the stationary side seal ring. Further, since it is mainly the stationary side seal ring that promotes the wear at an early stage, the stationary side seal ring is mainly replaced, which facilitates maintenance work such as disassembly, inspection, and replacement.

According to the second aspect of the present invention, the means for holding the rotating side seal ring is based on the high pressure water pressure from the elastic ring and the high pressure introducing hole. The difference in level of each seal ring piece due to the error and the unevenness of the mounting flange surface is extremely small. Therefore, the load sharing of each seal ring piece is smoothed, the water sealing performance is improved, and the leakage amount can be reduced.

In the third aspect, when the rotary seal ring rotates due to the rotation of the rotary shaft, heat is generated on the seal surface, and the seal ring piece of the rotary seal ring thermally expands. However, since a spacing piece having elasticity is arranged between the seal ring pieces arranged adjacent to each other,
This circumferential thermal expansion is mitigated.

Further, since the cooling groove is formed on the sliding surface of the spacing piece arranged between the respective seal ring pieces, high pressure water is applied to the sealing surfaces of the rotary side seal ring and the stationary side seal ring. Flow in, a fluid film is easily formed, heat generation due to friction is reduced, and the temperature rise of the seal ring can be suppressed. From the above, the occurrence of thermal cracking can be completely prevented.

In the present invention, a large amount of leakage may occur due to abnormal wear due to the mixing of a large amount of earth and sand or instantaneous damage to the rotary seal ring due to an abnormal impact force such as an earthquake. In order to prevent such an accident, a floating shaft sealing device is arranged at the upper end of the seal case, and the amount of leakage can be drastically reduced.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a shaft sealing device according to the present invention, FIG. 2 is a perspective view showing a seal ring piece of a rotary side seal ring, and FIG. 3 is a sectional view taken along the line AA of FIG. FIG. 4 is a sectional view taken along line BB in FIG. 1, FIG. 5 is a sectional view taken along line CC in FIG. 3, and FIG. 6 is a perspective view showing a spacing piece inserted between the seal ring pieces of the rotary side seal ring. FIG. 7 and FIG. 7 are explanatory diagrams showing pressing forces of the rotating side seal ring and the stationary side seal ring. 1 to 7, the same parts as those in the conventional configuration will be described using the same reference numerals as those in FIGS. 8 and 9.

As shown in FIG. 1, a rotary shaft 1 is provided with a flange 2 projecting therefrom, and a housing 6 is arranged so as to surround the flange 2. The housing 6 is integrated with a cover 7 shown in FIG. Is formed as a part of. A seal case 9 is arranged in the housing 6, and a detent bolt 24 is attached to the housing 6 and the seal case 9, and the detent bolt 24 prevents the seal case 9 from rotating.

Further, the spring 13 is a rotation stop bolt 2
The stationary side seal ring 25 is pressed against the rotating side seal ring 26 by being inserted between the large diameter portion 4 and the bolt mounting groove 9a of the seal case 9. The stationary side seal ring 25 is attached to the seal case 9 with a mounting bolt 27. The stationary seal ring 25 has a sealing surface coated with cemented carbide 28, while the rotating seal ring 26 is composed of a plurality of ceramic seal ring pieces 26a arranged adjacent to each other. Cemented Carbide 28 is a WC-Co alloy as well as a WC alloy.
-TiC-Co type, WC-TaC-Co type, WC-Ti
C-Ta (Nb) C-Co system etc. are mentioned.

On the upper surface of the flange 2, two grooves (circumferential grooves) 2a are formed in the circumferential direction, and two ring elastic bodies 29 are inserted into the two grooves 2a. As shown in FIG. 2, the seal ring piece 26a of the rotary side seal ring 26 has stepped portions 26b formed on the inner peripheral side and the outer peripheral side thereof, respectively. The stepped portion 26b is attached to the mounting flange 30a of the tightening ring 30. It is fixed to the upper part of the two ring elastic bodies 29 by fitting it in and tightening the tightening bolt 31. Here, as the material of the ring elastic body 29, a polymer compound such as rubber is used. Further, as shown in FIG. 3, the flange 2 is provided with as many high pressure water introducing holes 2b as there are seal ring pieces 26a between the concave grooves 2a, 2a, and a throttle plug is provided at an inlet of the high pressure water introducing holes 2b. 32 is attached.

Further, on the inner peripheral side of the upper end of the seal case 9, as shown in FIGS. 1 and 4, the seal case 33,
A floating shaft sealing device 40 including a floating seal 34, a coil spring 35, and a holding plate 36 is attached by a tightening bolt 37. In the floating shaft sealing device 40, the coil spring 35 is fitted in the outer peripheral groove of the floating seal 34 in the seal case 33. And the floating seal 34
Is a floating seal piece 34 divided into four in the circumferential direction.
It is composed of a.

Further, as shown in FIG. 5, a space piece 38 made of an elastic material is provided between the seal ring pieces 26a of the rotary side seal ring 26 by means of a tightening bolt 39 to secure the flange 2 to the flange 2.
Installed and fixed on. Further, as shown in FIG.
On the sliding surface side of 8, the cooling groove 38a and the water passage groove 38b are formed in the radial direction of the seal ring piece 26a.

Next, the operation of this embodiment will be described.

The stationary side seal ring 25 has an integral structure, and its sealing surface is coated with cemented carbide 28, while the rotating side seal ring 26 is composed of a plurality of seal ring pieces 26a made of ceramics as shown in FIG. It is configured. Therefore, unlike the conventional example shown in FIG. 9, there is no collision between the seal ring piece 22 of the stationary side seal ring 12 and the seal ring piece 15 of the rotating side seal ring 5 due to each step, and the damage of the seal ring piece due to the impact is prevented. can do.

Further, here, since the wear resistance of the ceramics is superior to that of the cemented carbide 28, the stationary side seal ring 25 is mainly worn, and the stationary side seal ring 25 becomes the stationary side seal ring 25 after replacement and is decomposed. Maintenance work such as inspection, replacement, etc. becomes easy.

FIG. 7 shows the interaction of forces when high pressure water pressure is applied to the shaft sealing device of this embodiment. In FIG. 7, the high-pressure water pressure P ₀ , the outer diameter D _K of the insertion portion of the O-ring 8 of the seal case 9, and the inner and outer diameters of the seal surface of the seal ring piece 26a are D _si and D _so , respectively. _Let the diameters up to the elastic body 29 be D _ri and D _ro , respectively. In this embodiment, D _K = D _so
Therefore, the force W _d for pushing down the seal case 9 and the force W _u for pushing up the seal case 9 by the high-pressure water pressure P ₀ are equal.

Therefore, the high-pressure water pressure P ₀ does not generate a pressing force on the seal surfaces of the stationary side seal ring 25 and the rotating side seal ring 26. This means that the spring 13
The pressing force W _b of the seal case 9 and the weight W _k of the seal case 9 are the pressing force W _{s of the} sealing surface. Therefore, the required pressing force W _so of the sealing surface is given by the pressing force W _b of the spring 13.
Easy to control.

On the other hand, the force for supporting the rotary seal ring 26 is the sum of the elastic deformation reaction force 2W _r of the two ring elastic bodies 29 and the fluid force W _p due to the high-pressure water pressure P ₀ (W _b = 2W _r +
W _p ), but the rigidity of the ring elastic body 29 needs to be large by designing (the diameters D _ri and D _ro of the ring elastic body 29) such that W _p > 2W _r. Disappear. As a result, it is possible to easily absorb an error in processing accuracy of each seal ring piece 26a of the rotary side seal ring 26 and a step caused by the unevenness of the mounting flange surface.

Further, the throttle plug 32 attached to the inlet of the high-pressure water introducing hole 2b shown in FIGS. 1 and 3 has an impact force acting on the seal ring piece 26a when the rotary seal ring 26 swings or moves up and down. Has a function of reducing the damping force by the damping force based on the backflow of the high pressure water of the throttle plug 32.

By the way, heat is generated due to friction on the sealing surfaces of the rotating side seal ring 26 and the stationary side seal ring 25. Due to this heat generation, the seal ring piece 26a of the rotation side seal ring 26 thermally expands in the circumferential direction,
Since the spacing pieces 38 having elasticity as shown in FIGS. 3, 5 and 6 are arranged between the seal ring pieces 26a, thermal stress due to thermal expansion hardly occurs.

On the other hand, as shown in FIGS. 3 and 6, a cooling groove 38a and a water passage groove 38b are formed on the sliding surface of the spacing piece 38 to positively cause a slight radial leakage, thereby rotating. Side seal ring 26 and stationary side seal ring 2
It is possible to supply cold water between the sealing surfaces of the seal ring 5 and 5, and to facilitate the formation of a fluid film and to suppress the temperature rise of the seal ring piece 26a. As a result, thermal cracking of the seal ring piece 26a can be prevented.

In normal operation, the stationary seal ring 2
A slight amount of leakage occurs from the sealing surface between the rotary seal ring 26 and the rotating side seal ring 26 and the water passage 38b of the spacing piece 38. By setting the inner diameter seal gap S of the floating seal 34 shown in FIG.
The flow resistance here can be made almost zero. That is, it does not have a sealing function in normal operation.

However, a large amount of the static side seal ring 25 or the rotary side seal ring 26 is generated when the ceramic seal ring piece 26a is damaged due to the occurrence of abnormal wear or abnormal vibration such as an earthquake due to the mixing of a large amount of earth and sand. Regarding the leakage, the flow resistance in the inner diameter seal gap S of the floating seal 34 rapidly increases, so that the amount of leakage can be drastically reduced. That is, by disposing the floating shaft sealing device 40 at the upper end of the seal case 9, the amount of leakage can be drastically reduced.

[0046]

As described above, according to claim 1 of the present invention, while the seal ring piece of the rotary side seal ring is made of a ceramic material, the seal surface of the stationary side seal ring is coated with cemented carbide. By doing so, it is possible to prevent cracks or loss of the seal ring due to the collision between the adjacent seal ring pieces of the stationary side seal ring and the step difference between the adjacent seal ring pieces of the rotary side seal ring as in the conventional case. be able to.

According to the second aspect of the present invention, a plurality of circumferential grooves are formed at a position facing the rotary seal ring of the flange, and a ring-shaped elastic body is inserted into the circumferential grooves so that the plurality of flanges are The high pressure water inlet holes are formed between the circumferential grooves, and the rotary side seal ring is held by the high pressure water pressure from the ring-shaped elastic body and the high pressure water inlet hole. It is possible to eliminate the step between the ring pieces, equalize the load sharing of the static load between the adjacent seal ring pieces, and prevent the seal ring pieces from being damaged by the impact force caused by the vertical vibration.

According to the third aspect, the cooling groove is formed between the seal ring pieces, and the elastic spacing pieces are arranged, so that friction between the rotating side seal ring and the stationary side seal ring is generated. Heat cracking can be prevented by cooling / removing heat generation and mitigating thermal stress due to thermal expansion in the circumferential direction between the adjacent seal ring pieces of the rotary side seal ring.

According to the present invention, since the floating shaft sealing device is arranged at the upper end portion of the seal case, the rotating side seal ring or the stationary side seal ring is abnormally worn due to the inclusion of earth and sand, or an earthquake occurs. When most of the sealing function is lost due to damage to the rotating side seal ring,
You can temporarily respond to an emergency.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a seal ring piece of a rotation side seal ring.

3 is an end view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

5 is a cross-sectional view taken along line CC in FIG.

FIG. 6 is a perspective view showing a spacer piece inserted between the seal ring pieces of the rotating side seal ring.

FIG. 7 is an explanatory view showing pressing forces of a rotating side seal ring and a stationary side seal ring.

FIG. 8 is a sectional view showing a conventional shaft sealing device.

FIG. 9 is a cross-sectional view showing a rotating-side seal ring piece in a conventional shaft sealing device.

[Explanation of symbols]

 1 spindle 2 flange 2a concave groove (circumferential groove) 2b high pressure water introduction hole 6 housing 9 seal case 24 non-rotating bolt 25 stationary side seal ring 26 rotating side seal ring 26a seal ring piece 26b stepped portion 27 mounting bolt 28 cemented carbide Alloy 29 Ring elastic body 30 Tightening ring 31 Tightening bolt 32 Throttle plug 33 Seal case 34 Floating seal 38 Spacing piece 38a Cooling groove 38b Water passage groove 40 Floating shaft sealing device

Claims (4)

[Claims] 1. A flange projecting from a rotary shaft, a housing arranged to surround the flange, a seal case arranged in the housing, and a plurality of circumferentially mounted flanges attached to the flange. A rotary side seal ring, in which seal ring pieces are arranged adjacent to each other, and a stationary side seal ring, which is arranged in pressure contact with the rotary side seal ring and attached to the seal case, wherein the rotary side seal A shaft sealing device, wherein a seal ring piece of the ring is made of a ceramic material, and a seal surface of the stationary side seal ring is coated with a cemented carbide. 2. A flange projecting from the rotary shaft, a housing arranged so as to surround the flange, a seal case arranged in the housing, and a plurality of seals attached to the flange in the circumferential direction. In a shaft sealing device comprising a rotating side seal ring in which ring pieces are arranged adjacent to each other, and a stationary side seal ring attached to the sealing case arranged in pressure contact with the rotating side seal ring, rotation of the flange. A plurality of circumferential grooves are formed at positions facing the side seal ring, a ring-shaped elastic body is inserted into the circumferential grooves, and high pressure water introduction holes are formed between the circumferential grooves of the flange. Then, the shaft sealing device is characterized in that the rotating side seal ring is held by the high pressure water pressure from the ring-shaped elastic body and the high pressure water introduction hole. 3. A flange projecting from the rotary shaft, a housing arranged so as to surround the flange, a seal case arranged in the housing, and a plurality of seals attached to the flange in the circumferential direction. In the shaft sealing device, which includes a rotating-side seal ring in which ring pieces are arranged adjacent to each other, and a stationary-side seal ring attached to the sealing case arranged in pressure contact with the rotating-side seal ring, A shaft sealing device, characterized in that a cooling groove is formed between the pieces, and an elastic piece is arranged. 4. A flange projecting from the rotary shaft, a housing arranged so as to surround the flange, a seal case arranged in the housing, and a plurality of seals attached to the flange in the circumferential direction. In a shaft sealing device comprising a rotating side seal ring in which ring pieces are arranged adjacent to each other, and a stationary side seal ring attached to the sealing case arranged in pressure contact with the rotating side seal ring, A shaft sealing device, wherein a floating shaft sealing device is provided at an upper end portion.