JPS6243180Y2 - - 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.

A conventional double mechanical seal (hereinafter simply referred to as a "mechanical seal") generally has a configuration shown in FIG. 1 (schematic sectional view of main parts). That is, to briefly explain based on the drawings, 1 is the rotation axis, 2 is the rotation axis 1
Seal boxes 3a and 3b are seat rings that loosely fit around the rotating shaft 1 and are integrally disposed near both ends inside the seal box 2. Also 4
Both driven rings a and 4b rotate together with the rotating shaft 1, and the surfaces in contact with the seat rings 3a and 3b respectively serve as sealed end faces.
The rotation mechanism 4b has the following configuration.

That is, reference numeral 5 denotes a retainer fixed to the rotating shaft 1 with a screw 7, and driven ring holders 6a and 6b are provided on the left and right sides of the retainer 5, and between these driven ring holders 6a and 6b, respectively. A plurality of drive pins 8 and intermediate springs 9 are installed alternately along the circumferential direction. Further, driven rings 4a and 4b are fitted into the driven ring pressers 6a and 6b, respectively, and are fixed by rotation stop pins not shown in the figure. That is, the driven rings 4a, 4b are the driven ring pressers 6a, 6.
b Since it is fixed to the rotating shaft 1 via the drive pin 8, retainer 5, and screw 7, it rotates as the rotating shaft 1 rotates, while the intermediate spring 9 moves the driven ring in the direction in which it leaves the driven ring pressers 6a and 6b, respectively. By applying pressure to the driven rings 4a and 4b, the driven rings 4a and 4b are always in contact with the seat rings 3a and 3b, respectively, so that a stable double-sealed end surface is obtained. By the way, as shown above, mechanical seals generally have a working pressure condition of 90
It is designed considering the case of ~100Kg/cm ² or less, and it is especially designed for cases of 90 to 100Kg/cm ² or more.
When used to seal the rotating shaft of a chemical device, etc. that handles high-pressure fluids of around 200 kg/ ^cm2 , the sealing effect deteriorates rapidly over time due to the reasons described below. There has been a strong desire to develop a mechanical seal that can provide a sufficient sealing effect even at the bottom.

The inventors of the present invention have been working diligently to develop high-pressure mechanical seals in response to such demands, and after closely observing the behavior of conventional mechanical seals in a high-pressure fluid atmosphere, they found that:
The following facts were discovered. That is, to explain based on FIG. 1, the seat ring 3a and the driven ring 4a
A gap 10 between each inner circumferential surface of and the outer circumferential surface of the rotating shaft 1
high pressure from the container body 12 (e.g. 100Kg/
cm ² ) fluid is loaded, and in order to maintain the seal surface stably under such conditions, the seal box 2 must have at least a pressure higher than that (e.g. 120 kg/cm ^{2 )} .
before and after). Note that the space 13 is at atmospheric pressure. At this time, as shown in Figure 2 (an enlarged view of Figure 1), a large bending stress is applied to the leading end A of the driven ring 4a, and the rear end B is strongly applied to the side peripheral surface Y of the driven ring holder 6a. Being pushed. Incidentally, the side circumferential surface Y forms the bottom surface of the character-shaped groove in the driven ring presser 6a, and so-called lap finishing cannot be applied to finish such a bottom surface, and the finishing accuracy is low. For example, by grinding or precision boring, the surface roughness μ can be processed to a maximum of about 0.003 (mm). For this reason, when the bending stress increases, a large strain occurs at the rear end B of the driven ring 4a, and when the tip A is also strained by the amount of this strain, the entire sealing surface is in contact from a microscopic perspective. In particular, the higher the pressure, the smaller the proportion of the entire surface contact, and the sealing performance will rapidly decrease. Therefore, in order to absorb such distortion and still ensure full contact on the sealing surface, it may be possible to make the tip A thicker (of course, the seat ring 3a should have the same thickness), but in this case, The thickness must be at least five times that of the case where the thickness is, for example, 50 kg/cm ² or less, and the diameter of the driven ring retainers 6a and 6b must also be enlarged, resulting in a change in the structure of the mechanical seal. This is not a good solution because it increases the size and production cost.

In view of this point, the present invention has a structure that does not cause distortion in the rear end B of the driven ring 4a even under high pressure, so that the sealed end surface can be maintained without particularly increasing the thickness of the tip A of the ring 4a. It was completed as a result of further research in order to provide a compact and economical mechanical seal that can maintain a sufficiently good sealing effect. It is formed into a flat surface, and the opposite end surfaces of the driven rings are brought into contact with each other, and O-rings are arranged on the surfaces in close contact between the outer circumferential surface of each driven ring and the inner circumferential surface of the driven ring presser. The main points are as follows.

The configuration and effects of the present invention will be explained below with reference to the drawings. Figure 3 shows the mechanical seal according to the present invention in a polymerization reaction vessel (pressure conditions are approx.
200Kg/cm ² ) is a longitudinal cross-sectional view of the main part when applied to the rotation shaft of a stirring blade, 31 is the rotation shaft, 3
2 is a seal box for the rotary shaft 31. Also 3
3a and 33b are seat rings disposed within the seal box 32 at predetermined intervals. In this arrangement, stationary ring receivers 34a and 34b fixed at both ends inside the seal box 32 are used.
Stationary rings 35a and 35b are fitted along the circumferential direction with a plurality of pins 36 and springs 37 interposed alternately, and the stationary rings 35a and 35b are
Also seat rings 33a, 33 via pins 38.
b, and seat ring 33b to seat ring 33a and stationary ring 35a.
and a cover 39a for the stationary ring 35b, respectively.
39b and stationary ring receivers 34a, 3
It is attached to 4b. The pins 36 and 38 are loosely fitted into each pin hole, forming a loose pin connection. That is, stationary rings 35a, 35
b are attached so as to be able to move slightly back and forth and up and down relative to the stationary ring receivers 34a and 34b, respectively, and the seat rings 33a and 33b are also mounted to be able to swing slightly relative to the stationary rings 35a and 35b, respectively. installed as possible. The seat rings 33a and 33b come into 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 rotating shaft 3 to
1, and its mounting structure is as described below, which is also a feature of the present invention. That is, both side surfaces of the retainer 41 are formed into perfect planes, and driven rings 40a and 4 are provided on both planes, respectively.
The opposite end surfaces of the two driven rings 40a and 40b are brought into contact with each other via locking pins not shown in the figure, and these driven rings 40a and 40b are connected to the upper driven ring retainer 4.
4 and the lower driven ring retainer 43
It is integrally arranged on the left and right sides of 1. 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 = 0.0003 mm).
The flatness is approximately 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 retainer 41 having the left and right driven rings 40a 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 the sleeve 45 and the screw 46.

Further, 47a and 47a' are high-pressure cooling liquid inlets, and 47b is a high-pressure cooling outlet, and a pressure (approximately 220 kg/cm ² ) slightly higher than the high-temperature sealing fluid (pressure approximately 200 kg/cm ² ) is applied to the space 48 within the seal box 32. In addition to applying a load to prevent thermal distortion of the sealed end surface as much as possible,
The stationary ring 35a, the seat ring 3a, the stationary ring 35b, and the seat ring 33b are sufficiently pressed against the driven rings 40a, 40b, respectively, so that a stable sealed end surface is formed.

As mentioned above, the space 49 is loaded with a sealing fluid with a pressure of about 200 kg/cm ² , and the space 50 is loaded with atmospheric pressure, so an O-ring is placed in an appropriate place to isolate them from each other except at the sealed end surface. It is set up. In particular, 51 to 54 are O-rings arranged in consideration of sealing between sealing fluid of about 200 Kg/cm ² and high-pressure cooling liquid of about 220 Kg/cm ² , and 55 to 58 are O-rings of 220 Kg/cm 2.
This O-ring is designed to provide a seal between the high-pressure coolant of Kg/cm ² and atmospheric pressure.

By the way, in the mechanical seal configured as described above, as shown in FIG. 4 (enlarged view of FIG. 3), a large bending stress is applied to the leading end A' of the driven ring 40a, and the rear end B' is It is strongly pressed against the side peripheral surface Ya' of the retainer 41. However, since both the rear end B' side end surface and the side circumferential surface Ya' of the driven ring 40a are lapped, the distortion generated on this contact surface can be reduced to an almost negligible level, and as a result, It is possible to suppress the distortion occurring at the tip end A' to a range that does not affect the sealing effect of the sealed end face. However, since the sliding precision at the close contact surface between the outer peripheral surface of the driven ring 40a and the inner peripheral surface Xa' of the upper driven ring holder 44 is not so high, the outer peripheral surface of the driven ring 40a, especially the tip
The problem is the distortion that occurs at the outer periphery C' in the direction approaching A', but as mentioned above, there is no
Since the ring 56 is arranged, a seal of about 220 kg/cm ² is created between the high-pressure coolant and the atmospheric pressure, that is, the space is passed from the space 48 through the inner circumferential surface Xa' of the upper driven ring holder 44 and the side circumferential surface Xa' of the retainer 41. Coolant leakage that continues in the 50s can be completely prevented.

The mounting structure and the effects of the driven ring 40b, retainer 41, and lower driven ring holder 43 are the same as described above, and the sealing effect of the sealed end surface is maintained, and the inner circumference of the lower driven ring holder 43 is removed from the space 48. Leakage of the coolant into the space 49 via the surface and the side peripheral surface of the retainer 41 can be completely prevented.

As mentioned above, the space 48 inside the seal box 32
Even when loaded with high-pressure coolant of approximately 220 kg/cm ² ,
Although the sealing effect of the sealed end face can be sufficiently maintained, this effect can be achieved by making the sliding surfaces of the driven rings 40a, 40b and the retainer 41 extremely high in precision, so that the rear end of each driven ring 40a, 40b is This was achieved without causing distortion and without particularly increasing the thickness of the tip, and furthermore, the driven rings 40a and 40b are formed using the collar-shaped retainer 4.
Since the structure is arranged in contact with both sides of 1, it is very compact. Further, the close contact surfaces of the driven ring 40a and the upper driven ring presser 44 and the driven ring 4
The O-rings 56 and 52 are arranged in the direction of the space 48 on the close contact surface of the lower driven ring holder 43 and the O-rings 56 and 52, respectively, so that the length of protrusion from the O-ring at each tip can be made as short as possible, which also makes it more compact. It can be said that it is a component that contributes to Such a compact mechanical seal is therefore also very economical.

The above embodiment is a representative example and does not limit the present invention, and any changes to the design of the material, shape, etc. of each part in accordance with the above-mentioned purpose are within the technical scope of the present invention. .

Furthermore, the mechanical seal of this invention is not limited to application to the rotating shaft of the above-mentioned chemical equipment, but can be applied to the rotating shaft of any industrial machine, automobile, aviation turbine, etc., and the sealed fluid is also aqueous solution,
This can be applied to any type of material, including lubricating oils and gases.

The present invention is constructed as described above, and it has become possible to provide a compact and economical stationary double mechanical seal for high pressure.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of the main part showing a conventional mechanical seal, FIG. 2 is an enlarged view of the part shown in FIG. 1, FIG. The figure is an enlarged view of a portion of FIG. 3. 1, 31... Rotating shaft, 2, 32... Seal box, 3a, 3b, 33c, 33b... Seat ring, 4a, 4b, 40a, 40b... Driven ring, 5, 41... Retainer, 6a, 6b ,43,
44... Driven ring presser.

Claims (1)

[Scope of utility model registration request] The seat rings are integrally arranged by the opposite end surfaces of the seat rings arranged at predetermined intervals in the seal box of the rotating shaft, and driven ring holders on the left and right sides of the retainer fixed to the rotating shaft. In a stationary compound mechanical seal in which each of the sealed end surfaces is formed by contacting the rear side end surfaces of each driven ring, both side surfaces of the retainer are formed into perfect flat surfaces, and the driven rings are formed on both flat surfaces. The opposite end surfaces are brought into contact with each other, and the contact surface between the outer circumferential surface of each driven ring and the inner circumferential surface of the driven ring presser is provided with an O.
A stationary double-acting mechanical seal characterized by an arrangement of rings.