JPH0215087Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of application of the invention) The invention is designed to perform shaft sealing in place of a main shaft sealing device such as a mechanical seal in an emergency when an abnormality occurs in the main shaft sealing device for normal operation. This invention relates to an emergency shaft sealing device.

(Conventional example) In a typical emergency shaft sealing device of this type, an annular hollow elastic seal member is attached to the inner circumference of the seal housing along the outer circumference of the rotating shaft, and the hollow elastic seal member is attached to the inner circumference of the seal housing. By sending pressurized fluid such as air into the inner circumference of the seal housing, the inner circumference of the seal member is elastically expanded and deformed so as to be brought into pressure contact with the outer circumference of the rotating shaft. It is configured to create a seal between it and the rotating shaft.

(Problems to be solved by the invention) However, in the conventional emergency shaft seal device described above, the outer circumference of the seal member is attached to the seal housing, and the inner circumference of the seal member is damaged by pressurized fluid. Since the amount of bulging deformation is approximately constant in the circumferential direction, if the rotating shaft is eccentric in the radial direction, the inner circumferential portion of the seal member that has been bulged deformed will spread over the entire circumferential direction. There is a risk that the seal will not be properly pressed against the rotating shaft, and therefore the sealing function will not be reliably exerted.

Moreover, if cracks or cracks occur in the sealing member during use, there is a risk that the sealing performance will drop sharply and significantly.

Furthermore, due to its nature, the emergency shaft sealing device is required to have a simple structure that can be easily maintained and inspected, and to be able to be made compact. There are disadvantages in that it tends to be complicated, requires a large installation space, and is difficult to miniaturize.

(Means for solving the problem) The present invention forms an annular housing groove along the outer circumference of the rotating shaft in the inner peripheral part of the seal housing, and the inner diameter of the housing groove is larger than the outer diameter of the rotating shaft. A large-diameter seal ring made of elastic material is housed in a loosely fitted state without contacting the rotating shaft, and the seal ring is placed on the seal housing side.
In order to bring the seal ring into pressure contact with the rotating shaft, a pressing means is provided to compress and deform the diameter using pressurized fluid, and a lubricant film is formed by baking or coating on the surface of the seal ring. To provide an emergency shaft sealing device which has a simple structure and is miniaturized, and which can reliably exhibit a sealing action.

(Function) According to the present invention, if the pressing means is activated in the event of an abnormality in the main shaft sealing device, the diameter of the seal ring is reduced by the back pressure of the pressurized fluid acting between the inner bottom of the housing groove and the seal ring. The seal ring is deformed and presses against the circumferential surface of the rotating shaft so as to tighten it, thereby sealing between the seal ring and the rotating shaft. Since a lubricating film is formed on the surface of the seal ring, this diameter reduction deformation of the seal ring is carried out smoothly regardless of whether it is tightly fitted into the housing groove, and the pressure contact is performed well. Power is expanded dramatically.
Similarly, when the pressure from the pressurized fluid is released, the seal ring quickly expands in diameter due to its lubricating film and moves back, releasing the emergency seal.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 1 onwards.

In FIGS. 1 to 4, 1 is a seal housing, 2 is a rotating shaft passing through the seal housing, and 3
4 is a main shaft sealing device, and 4 is an emergency shaft sealing device.

The main shaft sealing device 3 is a mechanical seal as an example, and includes a rotary sealing ring 6 that is fitted and supported on the rotary shaft 2 via an O-ring 5 etc. so as to be slidable in the axial direction but not rotatable. A stationary sealing ring 8 is fixedly supported by the seal housing 1 via a retainer 7 and is interposed between a spring retainer 9 fixedly attached to the rotating shaft 2 and the rotating sealing ring 6. It is composed of a spring 10 that presses the sealing ring 6 against the stationary sealing ring 8, and is configured to shield and seal the atmosphere side A and the sealed fluid side B by the relative rotational sliding contact between the sealing rings 6 and 8. ing.

The emergency shaft sealing device 4 is disposed near the main shaft sealing device 3 at a location immersed in the sealing fluid, and is constructed as follows according to the present invention.

That is, an annular housing groove 11 is formed in the circular inner peripheral portion 1b of the seal housing 1 along the outer peripheral surface of the rotating shaft 2, and the housing groove 11 has an inner diameter that is appropriately larger than the outer diameter of the rotating shaft 2. Made of elastic material with large diameter, i.e. synthetic rubber (for example, NBR, BR, SBR,
A seal ring 12 made of an elastomer material such as EPDN) or natural rubber is accommodated in a loosely fitted state in a non-contact manner to the rotating shaft 2, and pressure is applied to the seal housing 1 side to press the seal ring 12 to the rotating shaft 2. It is constructed by disposing a pressing means 13 that deforms the compressed diameter by using a pressurized fluid.

The seal ring 12 has a circular cross section, and is in contact with the groove bottom surface 11a of the accommodation groove 11, and is slightly compressed between both side wall surfaces 11b of the accommodation groove 11, so that it is substantially recessed into the accommodation groove 11. is housed in. Furthermore, a lubricant such as fluororesin is applied to the surface of the seal ring 12, and a coating (for example, Teflon coating, μ=
0.02), and due to the presence of this lubricating film 14, the diameter reduction deformation of the seal ring 12 within the housing groove 11 and its return movement are performed smoothly. Furthermore, the accommodation groove 11
In other words, the inner circumference 1b of the seal housing 1
The gap S between the rotating shaft 2 and the seal ring 12 must be set so that the seal ring 12 does not come off from the housing groove 11 even when the seal ring 12 is deformed to reduce its diameter. It is desirable to set the thickness to be smaller than 1/2 of the thickness W. However, this gap S is unlimited in order to prevent interference between the rotating shaft 2 and the seal housing 1 due to eccentricity in the radial direction of the rotating shaft 2 and corrosion due to a potential difference between the seal housing 1 and the rotating shaft 2. It is not something that can be kept small.

Further, the pressing means 13 is applied to the seal housing 1.
Groove bottom surface 11a and both side wall surfaces 11b of accommodation groove 11,
A pressurized fluid supply hole 16 communicating with the closed space 15 surrounded by the seal ring 11b and the seal ring 12 is formed, and a pressurized fluid supply device such as an air compressor (not shown) is connected to the supply hole 16. Seawater pressure on the sealed fluid side B flows from the supply hole 16 into the closed space 15.
It is configured to be able to supply air pressurized to a pressure _P2 that is appropriately higher than _P1 .

Therefore, when air at a pressure P ₂ is supplied to the closed space 15, this acts on the outer peripheral surface of the seal ring 12 facing into the closed space 15, pressing the seal ring 12 toward its center. The seal ring 12 is deformed to reduce its diameter, and the inner peripheral part of the seal ring 12 is brought into pressure contact with the outer peripheral surface of the rotating shaft 2 over its entire circumference, and the seal housing 1 and the rotating shaft 2 are connected through the seal ring 12. (Fig. 2 and 3)
(see figure).

Note that the cross section of the seal ring is not limited to a circular shape;
The seal ring 12 may have a trapezoidal shape as shown in FIG. 4A or a substantially rectangular shape as shown in FIG.
For a and 12b, the pressure contact surfaces 17 and 17 with respect to the rotating shaft 2 are tapered as shown in A or carved with a concave portion 18 as shown in B to reduce the contact area. For example, during sealing, the pressure from the pressurized fluid acts concentratedly on a narrow pressure contact area, so the sealing force increases significantly.

By the way, the air pressure P ₂ acting on the outer circumference of the seal ring 12 in order to deform the seal ring 12 to reduce its diameter is set to be higher than the sealing fluid pressure P ₁ acting on the inner circumference of the seal ring 12. Of course, in this case, in order to fully demonstrate the sealing function of the seal ring 12, the difference ΔP between both pressures P ₁ and P ₂ should be set as a pressure value with a safety factor taken into account. It is desirable to set it so that it is equal to or higher than the lower limit value.

With the above configuration, if any abnormality occurs in the main shaft sealing device 3, air at pressure P ₂ is supplied from the pressurized fluid supply hole 14, and the seal ring 12 acts on the outer circumference. As a result, the seal ring 12 is deformed to reduce its diameter, and its inner circumferential portion is pressed against the outer circumferential surface of the rotary shaft 2 over its entire circumference, thereby achieving good shielding and sealing from the sealed fluid side B.

At this time, the entire seal ring 12 is covered with the housing groove 11.
As shown in FIG.
2 can follow this, and the inner circumferential portion of the seal ring 12 is brought into good pressure contact with the outer circumferential surface of the rotary shaft 2 over its entire circumference, and there is no possibility that the sealing function will be impaired.

Furthermore, even if a crack or the like occurs in the seal ring 12, the entire seal ring 12 is deformed to a reduced diameter and is brought into pressure contact with the rotating shaft 2, thereby exerting its sealing function. Therefore, the sealing function does not deteriorate in any way due to the cracks and the like. Moreover, since the seal ring 12 is made of an elastic material such as synthetic rubber, its sealing performance is extremely good.

Furthermore, since the seal ring 12 is simply accommodated in the accommodation groove 11 formed in the inner peripheral portion 1b of the seal housing 1, the structure of the emergency shaft sealing device 4 is extremely simple. The installation space is also significantly reduced, allowing for miniaturization. This is an extremely important advantage for the emergency shaft sealing device 4, which is not normally used.

Furthermore, since the seal ring 12 is not hollow and its volume does not change at all even when it is deformed to reduce its diameter, the air pressure P ₂ applied to the outer circumference of the seal ring 12 is directly transferred to the rotating shaft 2. It acts as a pressure contact force, that is, a sealing force,
There is no need to set the air pressure _P2 higher than necessary.

When the sealing action by the emergency shaft sealing device 4 is no longer required, the supply of air from the supply hole 16 is stopped and the pressure acting on the outer circumference of the seal ring 12 is brought to atmospheric pressure. Then, the seal ring 12 is restored to its original shape by its own elastic force and returned to the position shown in FIG. ₁ by the sealing fluid pressure P1 acting on its inner circumference. I am forced to do it.

The emergency shaft sealing device according to the present invention can be effectively used in all devices that can use a seal ring made of an elastic material such as synthetic rubber.

Further, the pressing means 13 for reducing the diameter of the seal ring 12 is not limited to the above-mentioned embodiments, and in short, the pressing means 13 is used to apply a sealing fluid that acts on the outer circumference side of the seal ring 12 to the inner circumference thereof. (The fluid with a higher pressure among the fluids on both sides A and B that is shielded and sealed by the main shaft sealing device 3) may be used as long as it can act on a pressurized fluid with a higher pressure. Of course, the pressurized fluid is not limited to air, but may also be water or the like.

Furthermore, the cross-sectional shape of the seal ring 8 is not limited to the substantially rectangular, circular, and triangular shapes described in the embodiments, but hollow shapes are excluded.

(Effects) According to the present invention, in an emergency when an abnormality occurs in the main shaft sealing device, the seal ring is deformed in diameter by the pressure of the pressurized fluid and brought into pressure contact with the rotating shaft, thereby replacing the main shaft sealing device. Therefore, the seal ring can provide a seal between the seal housing and the rotating shaft. In this case, the volume of the seal ring does not change at all even if it is deformed to reduce its diameter, so the fluid pressure applied to the seal ring directly acts as a pressing force on the rotation shaft of the seal ring, that is, as a sealing force. As a result, the sealing action by the seal ring is effectively performed. In addition, even if the rotating shaft is eccentric, the seal ring can follow this, and the inner circumferential portion of the seal ring is brought into good pressure contact with the outer circumferential surface of the rotating shaft over its entire circumference. Good sealing function is exhibited.

Moreover, since a lubricating film is formed on the surface of the seal ring, the diameter reduction deformation and return movement of the seal ring within the accommodation groove during the above-mentioned emergency sealing and release are smooth, and the emergency shaft Proper operation of the sealing device can be expected, and the lubricating film also improves the corrosion resistance of the seal ring.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the emergency shaft sealing device according to the present invention, in which FIG. 1 is a longitudinal sectional side view, and FIG. 2 is a main part showing an operating state different from that in FIG. 1. FIG. 3 is a longitudinal side view showing the operating state when the rotating shaft is eccentric, and FIGS. 4A and 4B are sectional views showing modified examples of the seal ring. DESCRIPTION OF SYMBOLS 1...Seal housing, 1b...Inner peripheral part of seal housing, 2...Rotating shaft, 3...Main shaft sealing device, 4...Emergency shaft sealing device, 11...Accommodating groove, 1
2, 12a, 12b... Seal ring, 13...
Pressing means, 14...lubricating film.

Claims (1)

[Scope of utility model registration request] An annular housing groove is formed in the inner circumference of the seal housing along the outer circumference of the rotating shaft, and a seal ring made of an elastic material whose inner diameter is larger than the outer diameter of the rotating shaft is inserted into this housing groove. The seal ring is accommodated in a loosely fitted state without contacting the shaft, and a pressing means is disposed on the seal housing side for compressing and deforming the seal ring with pressurized fluid in order to bring the seal ring into pressure contact with the rotating shaft. An emergency shaft sealing device formed by baking or applying a lubricating film to the surface of the shaft.