JPS6316931Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compact and economical stationary dual mechanical seal mainly used for high pressure applications.

In stationary double-acting mechanical seals (hereinafter simply referred to as double-acting seals) for sealing rotary shafts built into various types of chemical industrial equipment, the amount of strain in the fluid-side seal increases as the pressure of the fluid to be sealed increases. As a result, the contact condition of the sealed end surfaces deteriorates and the sealing performance deteriorates, which is a problem.
That is, an example of the case where this type of double seal configuration is applied to the rotating shaft of a stirring blade in a polymerization reaction vessel (pressure condition is about 200 kg/cm ² , for example) is as shown in Figure 3 A (explanatory longitudinal cross-sectional view of the main part). It is. In the figure, 31 is a rotating shaft, and 32 is a seal box for the rotating shaft 31. Further, 33a and 33b are seat rings arranged within the seal box 32 at predetermined intervals. And regarding this arrangement,
Stationary rings 35a and 34b are fixed to both ends of the seal box 32, respectively.
35b are fitted along the circumferential direction with a plurality of pins 36 and springs 37 interposed alternately, and seat rings 33a, 33b are also attached to the stationary rings 35a, 35b via pins 38,
For the seat ring 33a and stationary ring 35a, also for the seat ring 33b and stationary ring 35b.
Covers 39a and 39b are fitted over these, respectively, and are attached to stationary ring receivers 34a and 34b. The pins 36 and 38 are loosely fitted into each pin hole, forming a loose pin connection.
That is, the stationary rings 35a, 35b are attached to the stationary ring receivers 34a, 34b, respectively, so that they can move up and down to some extent, and the seat rings 33a, 33b are also attached to the stationary rings 35a, 35, respectively.
Similarly, it is mounted so that it can swing somewhat relative to b. and seat ring 33a, 3
3b is in contact with driven rings 40a and 40b, which will be described later, to form a double-sealed end surface.

The driven rings 40a and 40b are both connected to the rotating shaft 3.
1 by integrally attaching the rotary shaft 31 to
The mounting structure is as follows. That is, both side surfaces of the retainer 41 are formed to be completely flat, and the opposing side end surfaces of the driven rings 40a and 40b are brought into contact with these flat surfaces via detent pins (not shown in the figure), respectively. The driven rings 40a and 40b are integrally disposed on the left and right sides of the retainer 41 by an upper driven ring holder 44 and a lower driven ring holder 43. In addition, both sides of the retainer 41 are lapped in advance to create an ultra-precise flat surface (in terms of surface roughness, μ=
It is finished to a flatness of about 0.0003mm (about 0.7μm or less). It goes without saying that the opposing end faces and sealed end faces of the driven rings 40a and 40b are lapped. In this way, the driven ring 40
The retainer 41 having left and right portions a and 40b is further fitted onto the stepped portion 31a of the rotary shaft 31 for positioning, and is fixed to the rotary shaft 31 by a sleeve 45 and a screw 46.

Further, 47a and 47a' are inlets for high-pressure cooling liquid (hereinafter referred to as sealing liquid), and 47b is an outlet for sealing liquid, and the space 48 in the seal box 32 is filled with sealing liquid to maintain the gas pressure to be sealed (approximately 200 kg/kg). cm ² ) is applied to prevent the occurrence of thermal distortion on ^the sealed end surface as much as possible, and the stationary ring 35a, seat ring 33a, stationary ring 35b, seat ring 33b Consideration has been made to sufficiently press and urge the husband and follower rings 40a and 40b to stabilize the sealed end surface.

As mentioned above, the space 49 is loaded with gas at a pressure of about 200 kg/cm ² and the space 50 is loaded with atmospheric pressure, so O-rings are placed at appropriate locations to isolate them from each other except at the sealed end faces. It is set up. In particular, 51 to 54 are about 200Kg/cm ² of gas and about
200Kg/cm ² This is an O-ring arranged in consideration of the sealing fluid, and 55 to 58 are 220Kg/cm2.
This O-ring is designed to provide a seal between the Kg/cm ² sealing liquid and atmospheric pressure. With the above-described configuration, consideration has been given to ensuring sealing performance at the double-sealed end face.

By the way, as already mentioned, the problem with such high-pressure compound seals is that as the pressure of the fluid to be sealed increases as the operating pressure of the device increases, the sealing performance deteriorates rapidly. It is. This is because the gas pressure in the space 49 is
When the temperature rises to ^more than 100Kg/cm2, the retainer 41
This is due to the fact that the thrust force (axial force as shown by the arrow in the figure) acting on the retainer 41 becomes too large to be ignored, and the amount of strain on the retainer 41 also increases. Almost the same degree of distortion occurs in the driven ring 40b held in the same manner, and the gas side sealed end face becomes an open state as shown in the figure, so that the leakage of the sealed fluid increases rapidly. It is.

The following is a summary of the methods that have been proposed so far to solve these inconveniences.

The axial thickness of the retainer 41 is increased.

The retainer 41 and the rotating shaft 31 are made integral.

The gas side end surface of the driven ring 40b is tapered in advance.

However, in this proposal, the mechanical seal structure becomes large and the manufacturing cost becomes high. In the other plan, it becomes difficult to lap finish the side surface of the retainer 41, and the finishing accuracy as described above cannot be obtained. Therefore, even if it is possible to reduce the amount of gas leakage under high-pressure operation, this cannot be a solution because the sealing performance during operation at intermediate pressure or lower conversely deteriorates. It is also undesirable in that the material cost increases. In the further proposal, a stress concentration part is formed on the gas side sealing end face, which accelerates wear of the stress concentration part, leading to early deterioration of sealing performance, which is also undesirable.

The present invention was developed with attention to these circumstances, and was completed after intensive study in order to develop a double seal that can ensure long-term stability of sealing performance without particularly increasing the structure of the mechanical seal part. Such a double seal of the present invention has the feature that at least the end face of the driven ring on the side of the fluid to be sealed on the retainer side is formed and arranged so as to correspond in advance to the side shape of the fluid to be sealed of the retainer when the fluid to be sealed is pressurized. The main points are as follows.

The configuration and effects of the present invention will be explained below with reference to the drawings of the embodiments, but the basic configuration that is the same as the conventional example will not be repeatedly explained, and the characteristic configuration of the present invention will be mainly explained.

FIG. 1 is a drawing corresponding to the enlarged view of the opening in FIG. 3A, and shows the set state of the multiple seal before pressurizing the polymerization reaction vessel. It can be seen that the retainer side end surfaces of the gas side driven ring 40b are arranged in a shape that corresponds in advance to the shape of the gas side surfaces of the retainer 41 under pressurized operation, which will be described later. Also, the optimum value of Δl in the figure varies depending on the load conditions, but according to experimental examples, the value of Δl varies depending on the gas pressure.
Under the conditions of 200Kgf/cm ² , seal side 240mm, and retainer axial thickness 40mm, 4 to 6.5μm is appropriate; similarly, when the gas pressure is set to 100Kgf/cm ² , 2 to 3μm is appropriate. It has been confirmed that Furthermore, it has been confirmed that if the value of Δl is too large, it becomes difficult to maintain the flatness of the sealed end surface when pressurizing the gas side. Considering these circumstances and processing accuracy, it is preferable to set the Δl value to 2 to 10 μm. Note that a vertical surface is formed on the sealed end surface as in the conventional case.

When the pressurized operation of the polymerization reaction vessel is started, the space 49 is loaded with high-pressure gas, and the space 48 is further loaded with a high-pressure sealing liquid. Therefore, a large thrust force acts in the axial direction, and the retainer 41 is greatly distorted as shown. At this time, the gas side driven ring 4
The retainer-side end surface of 0b contacts the gas-side end surface of the retainer 41, and this contact is, so to speak, in a state of uniform contact over the entire surface based on the above-described configuration. Therefore, the vertical flatness of the gas-side sealed end face is maintained sufficiently uniform, eliminating the risk of gas leakage.

Since the driven ring 40a on the atmospheric side is distorted to the same extent as the retainer 41, the sealed end surface is open at the bottom as shown in the figure. Therefore, leakage of the sealing liquid does not particularly increase due to the surface pressure effect. However, there is a risk that the driven ring 40a will wear out quickly, and if this is a concern, for example, the end surface of the driven ring 40a on the retainer side,
By forming the retainer 41 in advance to have a shape similar to the shape of both sides of the retainer 41 in the atmosphere during pressurized operation, the sealed end face on the atmospheric side can have almost the same vertical flatness as the sealed end face on the gas side, thereby extending the life of the retainer 41. It is also possible to

The above embodiment is a representative example and does not limit the present invention. All changes in the design of the materials, shapes, etc. of each part in accordance with the above-mentioned spirit are within the technical scope of the present invention.

In addition, the mechanical seal of the present invention is not limited to application to the rotating shafts of chemical equipment as described above, but can be applied to the rotating shafts of all kinds of industrial machinery, automobiles, aviation turbines, etc., and the sealing fluid can be aqueous solution,
Lubricating oil, gas, etc. can all be applied.

The present invention is constructed as described above, but the point is that at least the driven ring on the side of the fluid to be sealed has a cross-sectional shape that is highly adaptable, so that the sealing performance can be stably maintained over a long period of time. It has now become possible to provide a compact and economical stationary double-acting mechanical seal for high pressure.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a dual sealing end face illustrating a mechanical seal according to the present invention, Fig. 2 is a schematic operational diagram of the same, and Fig. 3A is a schematic sectional configuration diagram of main parts showing a conventional mechanical seal. Figure 3B is an enlarged view of the mouth of Figure 3A. 31... Rotating shaft, 32... Seal box, 3
3c, 33d... Seat ring, 40a, 40b
... Driven ring, 41 ... Retainer.

Claims (1)

[Scope of utility model registration request] Driven on the left and right sides of a retainer, which has opposing side end surfaces of seat rings arranged at predetermined intervals in a seal box of a rotating shaft, and both side surfaces fixed to the rotating shaft and formed into almost perfect planes. In a stationary double-acting mechanical seal in which each sealed end surface is formed by contacting the end surfaces of each driven ring integrally arranged with the rear side end surfaces of each driven ring by a ring retainer, the driven rings are configured to at least seal the fluid to be sealed. A stationary double mechanical seal characterized in that the retainer-side end surfaces of the ring on the sides are formed and arranged so as to correspond in advance to the shape of the side surfaces of the sealing fluid of the retainer when the sealing fluid is pressurized.