JPH0452535Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to mechanical seals, and is applicable when the sealing fluid is a slurry-based chemical and foreign matter is likely to form on the sealed end surface, or when the fluid is a hazardous chemical and external Even if there is a problem with leakage to the inside and outside, the fixed ring is divided into two parts, an inner and an outer part, a buffer chamber is provided on the sealed end side of the split surface, and sealing liquid is pressurized into the buffer chamber.
To provide an apparatus that can reliably prevent sealing liquid from leaking to the outside from the sealed end surface by differentiating the sealing widths at the sealed end surface of the outer two-split ring.

<Prior art> The basic structure of a mechanical seal is that a rotating ring provided on a rotating shaft and movable in the axial direction and a fixed ring provided on a casing face each other with sealed end faces perpendicular to the rotating shaft. and a fixed ring are brought into elastic contact with each other to seal the sealing liquid at the sealed end surface.The most common conventional one is as shown in FIG. They are brought into contact by a smooth sealed end surface 5.

However, when this mechanical seal is used in a centrifugal extractor, etc., if the sealing fluid is a slurry-based chemical, even if a small amount of this chemical enters the sealed end surface, the frictional heat and frictional motion on the end surface will cause As a result, foreign matter is generated, which acts as a kind of catalyst and increases the number of foreign matter in a chain reaction.As a result, the adhesion of the sealed end face deteriorates and the sealed fluid leaks to the outside P at an accelerated rate. .

Particularly when dangerous chemical liquids are being flowed, external leakage is particularly problematic.

FIG. 6 is a diagram showing the state of leakage of the sealing fluid, with elapsed time on the horizontal axis and leakage amount on the vertical axis. In the conventional technique, leakage starts already after approximately 15 minutes have elapsed.

Therefore, the conventional flushing technology, for example, was developed in a commercial project whose main purpose was to provide a breather.
Application to the mechanical seal disclosed in Japanese Patent No. 58-25170 is conceivable.

That is, as shown in FIG. 7, a rectangular groove 50 is formed in the center of the portion of the fixed ring 1 facing the sealed end surface 5, and a cooling liquid is injected into this groove 50 to seal the sealed end surface 5.
It is used to cool down the water.

<Problems with the Prior Art> In the mechanical seal described above, since the sealing end face 5 is cooled, the generation of foreign matter is suppressed, but as time passes, foreign matter adheres to the sealing end face 5 on the inner diameter side of the groove 50. The gap in this part widens, and a gap also occurs in the sealed end surface on the outer diameter side of the groove 50 that is connected to this part, so that the sealing fluid also leaks to the outside P, as shown in FIG. It ends up.

<Prior Art> Therefore, prior to the present invention, the inventor developed a prior art that can suppress the adhesion of foreign matter to the inner diameter side of the groove 50.

That is, in the prior art, the inner diameter side 50a of the groove 50 of the fixed ring 1 facing the sealed end surface 5 is configured to be deeper than the outer diameter side thereof, and the inner diameter side 50a is configured to be deeper than the outer diameter side of the fixed ring 1 facing the sealed end surface 5.
It was designed to prevent contact with the

<Problems with the prior art> In this prior art, even if foreign matter is generated on the inner diameter side of the sealed end surface 5, a gap is maintained between the inner diameter part and the rotating ring 2, so that this part is immediately removed. There is no attempt to spread out any further and push open the outer diameter side of the sealed end surface 5.

Further, since the coolant stored in the groove 50 is forced into the sealed fluid side through a narrow path on the inner diameter side of the sealed end face 5, foreign matter is less likely to adhere to the inner diameter side.

Therefore, as shown in FIG. 6, in this prior art, there is no leakage of the sealing fluid even after a little over 120 minutes.

However, if this mechanical seal is used for a long period of time, the outer diameter side of the sealing end face 5 will wear down due to friction and become flush with the inner diameter side.
The same problem as the prior art shown in FIG. 7 will arise.

The technical problem of the present invention is to reliably prevent sealing fluid from leaking at the sealed end face.

<Means for Solving the Problems> Means for achieving the above-mentioned problems will be described below with reference to FIGS. 1 to 4, which correspond to embodiments.

That is, in the present invention, in the mechanical seal having the above-mentioned basic configuration, the fixed ring 1 is composed of two members, the inner ring 6 and the outer ring 7, and the split surfaces of the inner and outer rings 6 and 7 are attached to the sealing end surface 5. A buffer chamber 8 is formed in the facing area, and the cross section of this buffer chamber 8 is formed into a triangle with one side on the sealing end surface 5, and the sealing liquid is supplied to the buffer chamber 8 at a pressure higher than the pressure of the sealing fluid. The sealing width at the sealing end surface 5 on the side facing the sealing fluid among the sealing end surfaces of the inner and outer rings 6 and 7 is
The sealing width is smaller than the sealing width at the sealing end face 5 on the side not facing the sealing fluid.

The mechanical seal includes both an internal flow type in which the inner ring 6 faces the sealing fluid and an outer flow type in which the outer ring 7 faces the sealing fluid.

In the case of an internal flow type mechanical seal, the inner ring 6
The sealing width A at the sealed end surface 5 of the outer ring 7 is set smaller than the sealing width B at the sealed end surface 5 of the outer ring 7.

In this case: (1) The sealed end surfaces 5, 5 of the inner and outer rings 6, 7 may both be formed into smooth surfaces along the circumferential direction.

(2) The sealed end surface 5 of the inner ring 6 may be formed into an edge shape along its circumferential direction so that the inner ring 6 is in line contact with the rotating ring 2.

(3) Three or more protrusions may be formed along the circumferential direction on the sealed end surface 5 of the inner ring 6 to bring the inner ring 6 into point contact with the rotating ring 2.

On the other hand, in the case of an external flow type mechanical seal, the sealing width A at the sealing end surface 5 of the outer ring 7 is set smaller than the sealing width B of the inner ring 6.

In this case, the outer ring 7 may be configured as described in (1) to (3) above.

The buffer chamber 8 may be formed on either side of the fixed ring 1 or the rotating ring 2.

For example, when the sealing fluid is a chemical, water or a solvent for dissolving the chemical is suitable as the sealing liquid to be filled in the buffer chamber 8.

<Operation> Hereinafter, an explanation will be given with reference to FIG. 1, taking an internal flow type mechanical seal as an example.

(1) The fixed ring 1 is composed of two members, the inner ring 6 and the outer ring 7. Even if a foreign substance is generated on the sealed end surface 5 of the inner ring 6, the outer ring 7 will not move independently from the inner ring 6. Since the sealing end face 5 continues to contact the rotary ring 2 by doing so, the sealing fluid does not leak to the outside.

(2) Since the hydraulic pressure of the sealing liquid is higher than the pressure of the sealing fluid, the amount of sealing fluid that enters the sealing end face 5 is reduced.

Furthermore, the sealed end surface 5 is cooled by the sealing fluid, and even if the sealing fluid enters, the rate at which foreign matter is generated is slowed down.

Therefore, the generation of foreign matter on the sealed end surface 5 on the inner side 6 can be considerably suppressed.

(3) Even if foreign matter adheres to the sealed end face 5, the sealing width A at the sealed end face 5 on the inner side 6 is smaller than that on the outer ring 7, and the cooling effect of the sealing liquid is high, so the inner ring 6 The amount of adhesion to is small.

Particularly, when the sealing end surface 5 of the inner ring 6 is formed into an edge shape or a protrusion shape, the sealing width A becomes smaller and the amount of foreign matter adhering to the inner ring 6 is further reduced.

(4) Therefore, the pressure of the sealing liquid pushes the foreign matter inside and eliminates it, making it easy to keep the sealed end surface 5 clean.

<Effects of the invention> The buffer chamber filled with the sealing liquid has a triangular cross section with one side on the sealing end surface, so it has a simple shape and is easy to process. Since air is less likely to accumulate when filling the liquid and the sealing liquid flows smoothly, the cooling effect is high and the adhesion of foreign matter can be reduced.

In addition, as shown in the action in (1) above, even if foreign matter is generated in one of the two halves of the fixed ring that faces the sealing fluid, the other ring that does not face the sealing fluid will remain independent. In addition to continuing to seal the sealed end face by moving, the effects of (2) to (4) can prevent foreign matter from adhering to the ring facing the sealing fluid, so the ring that does not face the sealing fluid is always kept clean. It is held in a sealing liquid,
It is possible to reliably prevent the sealing fluid from leaking to the outside.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a longitudinal sectional front view of an internal flow type mechanical seal showing a first embodiment, and the mechanical seal is constructed by having a fixed ring 1 facing a rotating ring 2 at a sealing end surface 5.

The rotating ring 2 is made of cemented carbide such as WC-Co alloy or cermet, and is attached to a hollow rotating shaft 3 through which a sealing fluid such as a chemical solution passes through the inside R. The rotating shaft 3 is surrounded by a main body cover 10. Ru.

The stationary ring 1 is attached to a stationary casing 4 of a centrifugal extractor, a pump, etc., and is brought into elastic contact with the rotating ring 2 via the elastic mechanism described below.

Note that the main body cover 10 is integrally fixed to the casing 4.

The fixed ring 1 is constructed by fitting a cylindrical inner ring 6 into a cap-shaped outer ring 7 having an opening therein, and both rings 6 and 7 are made of carbon graphite.

The outer ring 7 is slidably fitted into the inner peripheral surface of the casing 4, and a V-packet 11 is attached to this sliding surface to prevent leakage of the sealing fluid.

A plurality of springs 12 are provided in the circumferential direction of the casing 4.
is provided, and the outer ring 7 is brought into elastic contact with the rotating ring 2 via the V-packet 11 by the spring 12.

Further, the inner ring 6 is slidably fitted into the inner peripheral surface of the outer ring 7, and a V-packet 14 is attached to this sliding surface.

A plurality of springs 15 are attached to parts along the opening of the outer ring 7, and the inner ring 6 is attached to the springs 1.
5 makes elastic contact with the rotating ring 2 via the V-packet 14.

In particular, if the area of the left end surface 6b of the left and right end surfaces 6a, 6b perpendicular to the axial direction of the inner ring 6 is larger than the right end surface 6a, the pressing force that the left end surface 6b receives from the sealing fluid will be greater than that of the right end surface. Since the inner ring 6 overcomes the pressing force at 6a and is urged by the rotating ring 2, the spring 15 can be made very weak.

The V gaskets 11 and 14 are made of fluorine resin, and numerals 16 and 17 are gasket holders.

A buffer chamber 8 having a triangular cross section is formed in the circumferential direction of the contact surface between the inner circumferential surface of the outer ring 7 and the outer circumferential surface of the inner ring 6 at a portion facing the sealed end surface 5, and a buffer chamber 8 is formed in the outer ring 6. The buffer chamber 8 is connected to the fixed ring 1 through the communication hole 20.
communicates with the outside.

A sealing liquid supply source is connected to the communication hole 20 through a liquid supply line 19 made of polyethylene pipe, and a pressure pump and a pressure regulating valve (not shown) interposed in the liquid supply line 19 are used to seal the buffer chamber 8 to be filled. Set the liquid pressure slightly higher than the sealing fluid pressure.

Thereby, the sealing fluid that tries to enter the sealed end face 5 can be pushed back into the hollow shaft by the sealing fluid.

In this case, the polyethylene pipe 19 is easily connected to and detached from the nozzle 21 fixed to the communication hole 20 via the one-touch joint 22.

The sealing end surfaces 5 of the inner ring 6 and the outer ring 7 are both formed as smooth surfaces, but the sealing width A of the inner ring 6 is set smaller than the sealing width B of the outer ring 7.

As a result, the amount of foreign matter adhering to the sealed end surface 5 of the inner ring 6 can be reduced, and the sealing width of the outer ring 7 can be increased.
can be maintained with a clean sealant at all times.

FIG. 2 is a longitudinal sectional front view of the essential parts of an internal flow type mechanical seal showing a second embodiment of the present invention, in which the sealing end surface 5 of the outer ring 7 is formed into a smooth surface with a large sealing width, and the inner ring The sealed end surface 5 of the rotary ring 6 is formed into an edge shape along its circumferential direction so that the inner ring 6 is brought into line contact with the rotating ring 2.

In this embodiment, the sealing width of the inner ring 6 can be significantly reduced, and the amount of foreign matter attached can be significantly suppressed.

Therefore, the embodiment may be further modified, for example:
Three or more protrusions may be formed along the circumferential direction on the sealed end surface 5 of the inner ring 6 to bring the inner ring 6 into point contact with the rotating ring 2.

FIG. 3 shows a third embodiment of the present invention.
In the first and second embodiments described above, the buffer chamber 8 was formed on the side of the fixed ring 1, whereas in this embodiment, it was formed on the side of the rotating ring 2 so as to face the bisected surface of the fixed ring 1. It is.

However, the sealing width A between the inner ring 6 and the rotating ring 2 is kept smaller than the sealing width B between the outer ring 7.

In this case, the rotating ring 2 is formed into a smooth, edging or protruding shape along its circumferential direction, and the inner ring 2
can be brought into contact with.

FIG. 4 is a longitudinal sectional front view of an external flow type mechanical seal showing a fourth embodiment of the present invention, in which a rotating ring 2 fixed to a solid rotating shaft 3 and a fixed ring 1 fixed to a casing 4 are shown. The outer ring 7 of the fixed ring 1 faces the sealing end surface 5 and faces the sealing fluid flowing outside the rotating shaft 3 (that is, inside the main body cover 10) S, while the inner ring 6 do not have.

Therefore, it is the sealing end surface 5 of the outer ring 7 that the sealing fluid tries to enter first, so that the outer ring 7
The sealing width A with the rotating ring 2 at the sealed end surface 5 of
The sealing width B is set smaller than the sealing width B of the inner ring 6, so that the amount of foreign matter adhering to the outer ring 7 can be suppressed.

[Brief explanation of drawings]

1 to 4 show embodiments of the present invention.
The figure is a longitudinal sectional front view of an internal flow type mechanical seal showing the first embodiment, FIG. 2 is a longitudinal sectional front view of the main part of the same mechanical seal showing the second embodiment, and FIG. Figure 4 is a diagram equivalent to Figure 1, and Figure 5 is a diagram equivalent to Figure 1 of the external flow type mechanical seal showing the fourth embodiment.
The figure is a diagram equivalent to Figure 2 showing the prior art, Figure 6 is a diagram showing changes over time in the amount of leakage of the sealing fluid, Figure 7 is a diagram equivalent to Figure 2 showing the conventional technology involving flushing, and Figure 8 is a diagram showing flushing. FIG. 2 is a diagram corresponding to FIG. 2 showing a prior art without the above. 1... Fixed ring, 2... Rotating ring, 3... Rotating shaft,
4...Casing, 5...Sealed end face, 6...Inner ring, 7...Outer ring, 8...Buffer chamber, A...Sealing width at the sealed end face on the side facing the sealing fluid, B...
Seal width at the seal end facing away from the sealing fluid.

Claims (1)

[Claims for Utility Model Registration] 1. A rotating ring provided on the rotating shaft and movable in the axial direction, and a fixed ring provided on the casing, facing each other with sealed end surfaces perpendicular to the rotating shaft, and fixed to the rotating ring. by bringing the rings into pressure contact with each other,
In a mechanical seal that seals the sealing fluid at the sealed end surface, the fixed ring is composed of two members, an inner ring and an outer ring,
A buffer chamber is formed in the area where the split surfaces of the inner and outer rings face the sealed end surface, and the cross section of this buffer chamber is formed into a triangle with one side on the sealed end surface, so that the pressure of the sealed fluid is lower than the pressure of the sealed fluid. The buffer chamber is filled with sealing liquid at high pressure, and the sealing width at the sealing end face on the side facing the sealing fluid of each sealing end face of the inner and outer rings is equal to the sealing width on the sealing end face on the side not facing the sealing fluid. A mechanical seal that is characterized by being smaller than the stop width. 2. The mechanical seal according to claim 1, which is a registered utility model, characterized in that the mechanical seal is formed into an internal flow type, and one inner ring of the fixed ring faces the sealing fluid. 3. The mechanical seal according to claim 1, which is a registered utility model, characterized in that the mechanical seal is formed into an external flow type, and one outer ring of the fixed ring faces the sealing fluid. 4. The mechanical device according to claim 2 of the utility model registration, characterized in that the sealed end surface of the inner ring is formed into an edge shape along its circumferential direction so that the inner ring is in line contact with the rotating ring. sticker. 5. According to claim 2 of the utility model registration claim, which is characterized in that three or more protrusions are formed along the circumferential direction on the sealed end surface of the inner ring so that the inner ring is brought into point contact with the rotating ring. Mechanical seal as described. 6. The mechanical seal according to any one of claims 1 to 5 of the utility model registration claim, characterized in that a buffer chamber is formed in the fixed ring. 7. The mechanical seal according to any one of claims 1 to 5 of the utility model registration claim, characterized in that a buffer chamber is formed in the rotating ring.