JP2000161501A - Mechanical seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen the life of a mechanical seal and also ensure the discharge route to the outside of the particle generated inside the seal. SOLUTION: In the pump for pumping a pure water, a mechanical seal 18 is applied between a pump main body 11 and the rotary shaft 15 of an impeller 16. This mechanical seal 18 is provided slidably for a fixed side slide ring 22 formed by an alumina material while push-pressing a rotary side slide ring 23 formed by the alumina material by a compression coil spring 28. At least one of the fixed side slide ring 22 and rotary side slide ring 23 has a notched groove 35 from the inner periphery edge facing the space 32 of a liquid side toward the outer periphery edge facing the space 33 of a liquid system outside at the mutually facing slide surface 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical seal using an alumina material.

[0002]

2. Description of the Related Art Usually, a combination of silicon carbide (SiC) materials is used as a sliding material for a mechanical seal of a pump used for pumping pure water or ultrapure water. Above, due to the influence of the liquid quality of ultrapure water or the like, for example, precipitated silicon oxide causes corrosion damage or wear damage on the sliding surface of the seal, and the life of the seal is extremely short.

[0003] On the other hand, there is also a mechanical seal using a combination of cemented carbides. However, cemented carbides have a problem of eluting heavy metal substances and contaminating the liquid, and cannot be used for ultrapure water or the like.

[0004]

As described above, a mechanical seal that can sufficiently withstand a non-lubricating liquid such as ultrapure water has not been developed at present, and the short life of the mechanical seal is a problem. I have. On the other hand, the combination of cemented carbides has a problem of contamination by heavy metal substances.

Further, particles are generated from the inside of the seal or from a sliding surface between the sliding members. However, in the conventional mechanical seal, the particles cannot be discharged from the inside of the seal to the outside. There is also a problem that the concentration tends to stagnate and easily increase.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to extend the life of a mechanical seal and to secure a path for discharging particles generated inside the seal to the outside. is there.

[0007]

According to a first aspect of the present invention, there is provided a stationary sliding ring made of an alumina material, and a fixed sliding ring made of an alumina material pressed and slid on the fixed sliding ring. A rotating side sliding ring provided freely, and at least one of the fixed side sliding ring and the rotating side sliding ring is configured such that at least one of the sliding surfaces opposing each other has a peripheral edge from the liquid side to an outer peripheral edge of the liquid system. 3 is a mechanical seal having a groove formed by cutting into the groove.

[0010] With this, the entire area between the sliding surfaces of the fixed-side sliding ring and the rotating-side sliding ring of the alumina material, which does not cause the elution of the contaminant or the corrosion damage due to the material, but has the risk of wear damage, The liquid penetrates from the groove formed in the notch from the liquid-side periphery to the liquid-system outer periphery, and a liquid film is reliably formed over the entire area between the sliding surfaces. The lubrication of the liquid film extends the life. Further, the particles generated from the inside of the seal or the sliding surface once enter the groove, and are discharged to the outside of the liquid system together with a small amount of liquid slightly flowing out of the groove to the outside of the liquid system.

According to a second aspect of the present invention, the groove in the mechanical seal according to the first aspect is provided in a rotary side sliding ring.

[0010] Thus, the liquid film is formed between the sliding surfaces and the particles are discharged to the outside of the liquid system by the forcible force such as the centrifugal force generated by the rotation of the rotating side sliding ring. .

According to a third aspect of the present invention, there is provided a pump having an impeller used for pumping pure water, wherein the mechanical seal according to the first or second aspect is provided between a pump body and a rotating shaft of the impeller. It has been applied to.

[0012] Thus, the pump for pure water pumping ensures a long sealing life and discharges particles generated inside the seal to the outside of the liquid system to maintain the purity of the pumping liquid.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 and FIG. 2 show an embodiment of a mechanical seal, which is pure water or ultrapure water (hereinafter simply referred to as “pure water”).
This is an example in which an outside mechanical seal is attached to a vortex pump used for pumping of ultrapure water.

As shown in FIG. 1, the vortex pump has a pump cover 13 fixed to one side of a pump body 11 via an O-ring seal 12 and a bracket 14 fixed to the other side of the pump body 11, respectively. A rotating shaft 15 rotatably supported by a bearing mechanism (not shown) is fitted at the center, and a blade rotatably disposed between the pump body 11 and the pump cover 13 at the tip of the rotating shaft 15. A wheel 16 is fitted and integrated with a set screw 17.

A mechanical seal 18 is applied between the pump body 11 and the rotating shaft 15 of the impeller 16, and an oil seal 19 is applied between the bracket 14 and the rotating shaft 15.
Liquid tightness is maintained by each.

The mechanical seal 18 is provided on the pump body 11.
Via an O-ring seal 21, alumina oxide (Al
A fixed-side sliding ring 22 made of an alumina material such as ₂ O ₃ ) is integrally fitted. The fixed-side sliding ring 22 is formed of an alumina material such as alumina oxide (Al ₂ O ₃ ). The rotating side slide ring 23 is provided rotatably and slidably.

Fixed side sliding ring 22 and rotating side sliding ring 23
The sliding surfaces facing each other are the mechanical seal 18
Are formed respectively.

As described above, as the sliding material of the mechanical seal 18, a combination of alumina materials such as alumina oxide (Al ₂ O ₃ ) having the highest corrosion resistance to a used liquid such as pure water or ultrapure water is used. Used. The alumina material has no problem of elution of contaminants such as heavy metal substances and is not corroded and damaged by pure water or ultrapure water.

The rotary slide ring 23 is fitted to the rotary shaft 15 via an O-ring seal 25, and is fitted to the rotary shaft 15 and integrated with a set screw 26. Compression coil spring interposed between the drive ring 23
The rotation side slide ring 23 is pressed by the fixed side slide ring 22 by 28, and rotates integrally with the rotation shaft 15. 28
a is a spring cover provided on the sleeve 27 side, and 28b is a spring receiving plate provided on the rotating slide ring 23 side.

Between the inner peripheral surface of the fixed-side sliding ring 22 and the outer peripheral surface of the rotary shaft 15, there is provided a liquid side of the pump communicating with the pumping space 31. )), And a space 33 outside the liquid system is formed on the outer peripheral side of the rotating side sliding ring 23 and the spring cover 28a, etc. The space 33 outside the liquid system is It communicates with a drain hole 34 opened on the outer peripheral surface.

The space 32 on the liquid side and the space 33 outside the liquid system communicated with the drain hole 34 of the pump body 11 via the sliding surface 24 of the fixed-side sliding ring 22 and the rotating-side sliding ring 23. Is sealed.

The rotating side sliding ring 23 is a fixed side sliding ring.
The sliding surface 24 facing the sliding surface of 22 has a groove 35 cut from the periphery facing the space 32 on the liquid side to the periphery facing the space 33 outside the liquid system.

That is, as shown in FIG. 2, the groove 35 is formed by cutting from the inner peripheral edge facing the space 32 on the liquid side to the outer peripheral edge facing the space 33 outside the liquid system.
2A is an example in which a plurality of rectangular grooves 35 are cut in the radial direction, and FIG. 2B is an example in which a plurality of circular grooves 35 are formed in the radial direction. (C)
This is an example in which a plurality of square-shaped grooves 35 are cut obliquely from the radial direction toward the opposite side to the rotation direction.

Each groove 35 has a closed portion 36 formed on the outer peripheral side so as not to directly communicate with the space 33 outside the liquid system.
Since the two sliding surfaces 24 are in such a shape as to keep surface contact with each other at the closing portion 36, almost liquid tightness is maintained.

On the other hand, by forming the closing portion 36 as thin as possible and bringing the groove 35 closer to the space 33 outside the liquid system,
A small liquid flow path for discharging a liquid containing particles generated from the sliding surface 24 or the like during the operation of the pump or particles accumulated inside the mechanical seal 18 from the groove 35 to the space 33 outside the liquid system. To prevent contamination of the pump liquid and maintain a non-particle environment.

This groove 35 is a sliding surface of the fixed-side sliding ring 22.
24, or may be formed on both sliding surfaces 24 of the fixed-side sliding ring 22 and the rotating-side sliding ring 23, respectively. Further, the groove 35 may be provided at only one location, or may be radially provided at a plurality of locations.

As described above, one or both of the fixed-side sliding ring 22 and the rotating-side sliding ring 23 have the sliding surfaces 24.
One or more grooves 35 in the radial or oblique direction from the liquid side to the outside of the liquid system are arranged so as not to communicate with the space 33 outside the liquid system. With the action, the liquid is forced to enter between the sliding surfaces 24,
The formation of a liquid lubricating film (liquid film) between the sliding surfaces 24 is promoted. The liquid film formed in this way improves liquid lubricity, compensates for poor sliding characteristics when alumina materials are combined, and prevents the sliding surface 24, that is, the seal surface, from being worn or damaged, Extend the life of the mechanical seal 18.

Next, the operation of the embodiment shown in FIG. 1 will be described.

When the liquid pressure acts on the liquid-side space 32, the liquid is divided between the sliding surfaces 24 through the inner peripheral edges of the fixed-side sliding ring 22 and the rotating-side sliding ring 23 and the groove 35 and the like. The applied pressure acts to form a liquid film between the sliding surfaces 24.

During the operation of the pump, the liquid pressure in the groove 35 and the centrifugal force due to the rotation act between the sliding surfaces 24 to forcibly promote the formation of a liquid film between the sliding surfaces 24. ,
A slight flow of leaking liquid toward the outer peripheral side occurs.

The particles generated inside the seal or between the sliding surfaces 24 are discharged to the outside by the flow of the leaking liquid, and the non-particle state inside the seal can be maintained. That is, by bringing the groove 35 close to the space 33 outside the liquid system, the liquid containing particles can be reliably discharged outside the liquid system during operation.

On the other hand, at the time of stoppage, the two sliding surfaces 24 are kept in surface contact with each other at the closing portion 36 on the outer peripheral side, and liquid tightness is maintained.

The particles or the liquid containing the particles discharged into the space 33 outside the liquid system are discharged out of the apparatus through a drain hole 34 opened in the pump body 11.

In this manner, the sliding surface 24 of the fixed-side sliding ring 22 and the rotating-side sliding ring 23 made of an alumina material, which has no danger of elution of a contaminant or corrosion damage as a material, but has a risk of wear damage. The liquid invades into the entire area from the groove 35 formed by cutting from the liquid-side periphery to the liquid-system outer periphery,
Since the liquid film is reliably formed in the entire area between the sliding surfaces 24, the service life is extended by the lubricity of the liquid film, and the particles generated on the sliding surface 24 and the like once enter the groove 35. Thereafter, the liquid is discharged to the outside of the liquid system together with a small amount of liquid slightly flowing out of the groove 35 to the space 33 outside the liquid system.

Further, when the groove 35 is provided in the rotating sliding ring 23, the liquid between the two sliding surfaces 24 is forced by a centrifugal force or the like generated by the rotation of the rotating sliding ring 23. Formation of a film and discharge of particles to the outside of the liquid system are effectively performed.

The forcing force is applied to the groove 35 shown in FIGS. 2A and 2B.
2C, the centrifugal force acts on the liquid, and in the groove 35 of FIG. 2C, in addition to the centrifugal force, the force of taking the liquid into the groove 35 by the rotation of the rotating side sliding ring 23 acts.

As described above, a long-term seal life is ensured by the pump for pure water pumping, and particles generated from the sliding surface 24 or the like or particles accumulated inside the seal are discharged to the outside of the liquid system. To maintain the purity of the pumped liquid.

FIGS. 3 and 4 show another embodiment of the mechanical seal 18 for pumping pure water or ultrapure water (hereinafter, simply referred to as “pure water” also includes ultrapure water). This is an example in which an inside mechanical seal is attached to a vortex pump used for liquid. In the description of this embodiment, the same parts as those of the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof may be omitted.

As shown in FIG. 3, the pump body 11 and
The mechanical seal 18 applied between the rotary shaft 15 that rotates the impeller 16 is formed of an alumina material such as alumina oxide (Al ₂ O ₃ ) on the pump body 11 via an O-ring seal 21. The fixed-side sliding ring 22 is integrally fitted,
A rotating sliding ring 23 made of an alumina material such as alumina oxide (Al ₂ O ₃ ) is slidably provided on the side surface of the fixed sliding ring 22 on the side of the impeller 16. A sliding surface 24 of the mechanical seal 18 is formed between the surfaces where the side sliding ring 22 and the rotating side sliding ring 23 face each other and abut against each other.

The rotating side sliding ring 23 is fitted to the rotating shaft 15 via an O-ring seal 25, and is formed between a spring cover 28a fixed to the impeller 16 and a spring receiving plate 28b of the rotating side sliding ring 23. Compression coil spring 28 interposed between
As a result, the sliding surface 24 of the fixed-side sliding ring 22 is pressed, and the rotating-side sliding ring 23 rotates integrally with the rotating shaft 15.

On the outer peripheral side of the rotating side sliding ring 23 and the spring cover 28a, a space 32 on the pump inner liquid side (hereinafter, this pump inner liquid side is simply referred to as “liquid side”) communicating with the pumping space 31 is provided. Also, a space 33 outside the liquid system is formed between the inner peripheral surface of the fixed-side sliding ring 22 and the outer peripheral surface of the rotating shaft 15, and this space 33 is formed in the drain hole 34 of the pump body 11. The space 32 on the liquid side and the space 33 on the outside of the liquid system are communicated with each other, and are sealed via the sliding surfaces 24 of the fixed-side sliding ring 22 and the rotating-side sliding ring 23.

The rotating side sliding ring 23 is a fixed side sliding ring.
The sliding surface 24 facing the sliding surface of 22 has a groove 35 cut from the periphery facing the space 32 on the liquid side to the periphery facing the space 33 outside the liquid system.

That is, as shown in FIG. 4, the groove 35 is formed by cutting from the outer peripheral edge facing the space 32 on the liquid side to the inner peripheral edge facing the space 33 outside the liquid system.
FIG. 4A is an example in which a plurality of rectangular grooves 35 are cut in the radial direction, and FIG. 4B is an example in which a plurality of circular grooves 35 are formed in the radial direction. (C)
This is an example in which a plurality of square-shaped grooves 35 are cut obliquely from the radial direction toward the opposite side to the rotation direction.

Each groove 35 has a closed portion 36 formed on the inner peripheral side so as not to directly communicate with the space 33 outside the liquid system.
Since the two sliding surfaces 24 are kept in surface contact with each other at the closing portion 36, they are almost liquid-tight.

On the other hand, by forming the closing portion 36 as thin as possible and bringing the groove 35 close to the space 33 outside the liquid system,
A small liquid flow path for discharging a liquid containing particles generated from the sliding surface 24 or the like during the operation of the pump or particles accumulated inside the mechanical seal 18 from the groove 35 to the space 33 outside the liquid system. To prevent contamination of the pump liquid and maintain a non-particle environment.

This groove 35 is a sliding surface of the fixed side sliding ring 22.
24, or may be formed on both sliding surfaces 24 of the fixed-side sliding ring 22 and the rotating-side sliding ring 23, respectively. Further, the groove 35 may be provided at only one location, or may be radially provided at a plurality of locations.

As described above, also in the embodiment shown in FIGS. 3 and 4, one or both sliding surfaces 24 are radially or obliquely moved from the space 32 on the liquid side to the space 33 outside the liquid system. One or more grooves 35 are provided so that they do not communicate with the outside of the liquid system, and liquid is forced between the sliding surfaces 24 from the grooves 35 and the like by the liquid pressure increased in the pumping space 31 during operation of the pump. To form a liquid lubricating film (liquid film) between the sliding surfaces 24. The liquid film formed in this way improves liquid lubricity, compensates for poor sliding characteristics when alumina materials are combined, and prevents the sliding surface 24, that is, the seal surface, from being worn or damaged, Mechanical seal 18
To extend the service life.

As described above, the mechanical seal 18 formed in each embodiment is made of an alumina sliding material that does not elute heavy metal substances or the like during pumping of pure water or ultrapure water. The structure is such that particles generated from the seal portion during operation or particles accumulated inside the seal are released to the outside by the groove 35 provided on the sliding surface 24, thereby preventing a possibility that impurities are mixed in the pump liquid. .

Further, by using a combination of alumina materials, which are the sliding materials having the highest corrosion resistance to pure water or ultrapure water, corrosion damage is completely eliminated.

Pumped liquid such as pure water or ultrapure water is a liquid having poor liquid lubricity. If alumina materials are used as they are, abrasion damage of the sliding surface 24 due to poor lubrication between the sliding surfaces 24 will occur. Although it occurs, a groove 35 provided on the sliding surface 24 is formed.
Thereby, the formation of a liquid film between the sliding surfaces 24 is promoted, and the liquid lubrication state is improved.
The life of the seal can be extended.

Therefore, the mechanical seal 18 has a seal structure capable of keeping the pump liquid in a clean state, and can be used for a long period of time even under bad use conditions such as corrosiveness and lubricity. Life can be obtained.

[0053]

According to the first aspect of the present invention, the use of the fixed-side sliding ring and the rotating-side sliding ring made of alumina material can prevent the elution of pollutants and the possibility of corrosion damage as a material. The liquid is surely penetrated from the groove formed by cutting from the liquid-side periphery to the liquid-system outer periphery over the entire area of the alumina material having a possibility of abrasion damage, and the liquid film is formed over the entire area between the sliding surfaces. The liquid film can be reliably formed, and the lubricating property of the liquid film can extend the life. Furthermore, after particles generated inside the seal or on the sliding surface are once introduced into the groove, they can be reliably discharged to the outside of the liquid system together with a small amount of liquid that slightly flows out of the groove from the groove. Can be secured.

According to the second aspect of the present invention, since the groove is provided in the rotating side sliding ring, the groove between the sliding surfaces is formed by a centrifugal force or the like generated by the rotation of the rotating side sliding ring. The formation of the liquid film and the discharge of particles to the outside of the liquid system can be more effectively achieved.

According to a third aspect of the present invention, in the pump having an impeller used for pumping pure water, the mechanical seal according to the first or second aspect is provided between the pump body and the rotating shaft of the impeller. Since this is applied, a long-term seal life can be ensured by the pump for pure water pumping, and particles generated inside the seal can be discharged to the outside of the liquid system to maintain the purity of pure water.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a mechanical seal of the present invention.

2A is a front view showing a first example of a rotating side sliding ring of the mechanical seal of FIG. 1, FIG. 2B is a front view showing a second example of the rotating side sliding ring, and FIG. FIG. 7 is a front view showing a third example of the rotating side sliding ring.

FIG. 3 is a sectional view showing another embodiment of the mechanical seal of the present invention.

4A is a front view showing a first example of a rotating side sliding ring of the mechanical seal in FIG. 3, FIG. 4B is a front view showing a second example of the rotating side sliding ring, and FIG. FIG. 7 is a front view showing a third example of the rotating side sliding ring.

[Explanation of symbols]

 11 Pump body 15 Rotary shaft 16 Impeller 22 Fixed side sliding ring 23 Rotating side sliding ring 24 Sliding surface 35 Groove

Claims (3)

[Claims] 1. A fixed-side sliding ring made of alumina material, and a rotating-side sliding ring formed of alumina material and slidably provided while being pressed against the fixed-side sliding ring. At least one of the fixed-side sliding ring and the rotating-side sliding ring has a groove formed by cutting from a liquid-side periphery to a liquid-system outer periphery on sliding surfaces facing each other. Mechanical seal. 2. The mechanical seal according to claim 1, wherein the groove is provided in the rotation-side sliding ring. 3. The mechanical seal according to claim 1, wherein the pump having an impeller used for pumping pure water is applied between a pump main body and a rotation shaft of the impeller.