JPH059664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention can be used to replace a main shaft sealing device for normal operation, such as a gland packing, cannical seal, end face lip seal, etc., in an emergency when an abnormality occurs. The present invention relates to an emergency shaft sealing device for a rotary shaft used to perform shaft sealing, and which is suitable as a shaft sealing device for various liquid devices, stern tubes, etc.

(Conventional Example) A typical emergency shaft sealing device of this kind for a rotary shaft, which is used in conjunction with a main shaft sealing device in a stern tube sealing device or a pump shaft sealing device, for example, has a By attaching the outer periphery of an annular hollow elastic seal member along the outer periphery of the rotating shaft, and sending pressurized fluid such as air into the hollow part of this seal member, the inner periphery of the seal member is attached to the outer periphery of the rotating shaft. Some seals are configured to elastically bulge and deform in order to come into pressure contact with a surface, thereby creating a seal between the inner peripheral portion of the seal housing and the rotating shaft.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional emergency shaft sealing device for a rotating shaft, the outer periphery of the sealing member is attached to the seal housing, and the inside of the sealing member is damaged by pressurized fluid. Since the amount of bulging deformation of the peripheral portion is approximately constant in the circumferential direction, if the rotating shaft is eccentric in the radial direction, the bulging deformed inner peripheral portion of the seal member will be 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 their nature, emergency shaft seal devices used in various fluid equipment such as pumps are required to have a simple structure that is easy to maintain and inspect, and to be able to be made compact. In recent years, it has become mandatory for stern tube seal devices to be equipped with an emergency shaft seal device from the perspective of vessel safety, but with the configuration described above, the structure tends to become complicated. Moreover, it not only has the disadvantage that it requires a large installation space, making it difficult to downsize, but also has the disadvantage of lacking safety.

The present invention has been made in view of the above circumstances, and although it has a simple structure and can be made compact, even if the rotating shaft is eccentric in the radial direction, the entire circumference of the seal ring can be moved around the rotating shaft in an emergency. It is an object of the present invention to provide an emergency shaft sealing device for a rotating shaft that can be brought into uniform pressure contact with the outer circumferential surface and can reliably and satisfactorily exhibit a predetermined shaft sealing function.

(Means for Solving the Problems) In order to achieve the above object, the emergency shaft sealing device for a rotating shaft of the present invention, which performs shaft sealing in place of the main shaft sealing device in the event of an emergency of the main shaft sealing device, is provided. An annular storage groove is formed in the inner circumferential portion of the housing along the outer periphery of the rotating shaft, and both side walls are parallel to each other and perpendicular to the axis of the rotating shaft. A solid seal ring made of an elastic material and made of an incompressible material with a diameter larger than the diameter is placed between the rotating shaft and the inner circumferential surface of the seal ring, which is smaller than (1/2) the wall thickness of the seal ring. The seal ring is accommodated in a loosely fitted state with a gap between the seal ring and the seal ring, 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. A narrow protruding portion is formed on the pressure contact surface of the seal ring to protrude toward the circumferential surface of the rotating shaft.

Note that the above-mentioned solid seal ring made of an elastic material made of an incompressible substance refers to a solid seal ring whose volume remains the same even when the pressure is increased and the seal ring is elastically deformed.

(Function) According to the present invention configured as described above, when an abnormality occurs in the main shaft sealing device, the pressing means is activated to apply pressurized fluid to the back surface of the seal ring, thereby preventing the problem from occurring. A solid seal ring made of a compressible material is pressed uniformly over its circumferential direction, and is deformed to reduce its diameter so as to wrap around the outer peripheral surface of the rotating shaft. Here, the amount of deformation of the seal ring is large, about (1/2) of its wall thickness, and the narrow protrusion of the pressure contact surface of the seal ring is in pressure contact with the circumferential surface of the rotating shaft. Therefore, it is possible to concentrate the pressurizing force of the pressurized fluid on the narrow width protrusion, and to exert a very high sealing force in relation to the pressurizing force. In addition, since the seal ring itself is solid and made of an incompressible material, even if the rotating shaft is slightly eccentric in the radial direction, the seal ring will follow it and will be able to rotate around the entire circumference in the circumferential direction. This results in uniform and strong pressure contact, allowing the shaft sealing function to be reliably and satisfactorily exerted in an emergency.

(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, with both side walls parallel to each other and perpendicular to the line of the rotating shaft 2. , the housing groove 11 is made of an elastic but incompressible material, i.e., synthetic rubber (for example, NBR, BR, SBR, EPDN), the inner diameter of which is appropriately larger than the outer diameter of the rotating shaft 2.
Alternatively, a solid seal ring 12 made of an elastomer material such as natural rubber is housed in a loosely fitted state without contact with the rotating shaft 2, and pressure is applied to the seal housing 1 side to press the seal ring 12 against the rotating shaft 2. It is constructed by disposing a pressing means 13 that deforms the compressed diameter by using a pressurized fluid.

In FIGS. 1 to 3, the seal ring 12 has a substantially rectangular cross section, and is in contact with the bottom surface 11a of the housing groove 11, as well as on both side wall surfaces 11b of the housing groove 11.
It is accommodated in the accommodation groove 7 in a substantially recessed state in a slightly compressed state between the sections 11b. Further, each side wall surface 11b of the housing groove 7 is coated with a lubricant such as fluororesin.
Coated by baking, housing groove 1
The seal ring 12 housed in the rotary shaft 1 is deformed to reduce its diameter, that is, moved in the direction of the rotating shaft 2, smoothly. Furthermore, the gap S between the entrance portion of the housing groove 11, that is, the inner peripheral portion 1b of the seal housing 1 and the rotating shaft 2, is such that even when the seal ring 12 is deformed to reduce its diameter, the seal ring 12 is removed from the housing groove 7. It is necessary to set it so that it does not separate, and it is set smaller than 1/2 of the wall thickness W of the seal ring 8. 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.
A pressurized fluid supply hole 14 for applying back pressure is formed on the outer peripheral surface of the seal ring 12 of the housing groove 11, and a pressurized fluid supply device such as an air compressor (not shown) is connected to this supply hole 14. It is configured such that air pressurized to a pressure P ₂ that is appropriately higher than the fluid pressure P ₁ of the sealing fluid B can be supplied from the supply hole 14 to the outer circumferential surface of the seal ring.

Therefore, when air at a pressure P ₂ is supplied to the housing groove 11, the air is applied to the outer circumferential surface of the seal ring 12, and the seal ring 12 is pressed toward its center. As a result, the seal ring 12 becomes circular. The diameter is uniformly reduced in the entire circumferential direction, and the pressure contact surface 15 on the inner peripheral side 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 ring 12 is The space between the seal housing 1 and the rotating shaft 2 is hermetically sealed (see FIGS. 2 and 3).

Furthermore, in order to make the sealing effect during the above-mentioned pressure welding remarkable, the pressure contact surface 15 of the seal ring 12 is formed into a tapered shape whose width is gradually reduced toward the outer peripheral surface of the rotating shaft and whose tip protrudes in a triangular shape. Therefore, during the press-contact process, the pressure is concentrated on the narrow protrusion 16 at the tip of the press-contact surface. The increase in the sealing effect due to the tapered shape of the pressure contact surface is not limited to the above-mentioned triangular surface, but can also be achieved by, for example, the modified shape shown in Fig. 4 A to E. A concave part 17 is carved in the part, and narrow protrusions 16a, 16a are formed on both sides of the concave part 17.
A raised protrusion 16b is formed in the center of the 5b,
In C, the cross section of the seal ring 12 is made circular, and fin-like protrusions 16c, 16c are expanded on the compression side, and in D, the cross section itself of the seal ring 12 is made triangular, so that the tapered protrusions 16d are formed. In E, the inner circumferential surface which is the pressure contact surface is formed into a wave shape, and the ridges are formed into narrow protrusions 16.
e, 16e.

By the way, the air pressure P ₂ that is applied to the outer peripheral surface of the seal ring 12 to reduce the diameter of the seal ring 12 is set to be higher than the sealing fluid pressure P ₁ that is applied to the inner peripheral part of the seal ring 12. Of course, it is necessary to set
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 is
It is desirable to set the pressure value so that it is equal to or higher than the lower limit value taking into account the safety factor.

With the above configuration, if any abnormality occurs in the main shaft sealing device 3, air at a pressure of P ₂ is supplied from the pressurized fluid supply hole 14 and applied to the outer circumference of the seal ring 12. 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 14 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, in the embodiment, the seal ring 1
In order to smoothly move or reduce the diameter of the seal ring 12, each side wall surface 11b of the housing groove 11 is coated with a lubricant. It is not always necessary depending on the conditions such as the size of the

Further, the pressing means 13 for deforming the seal ring 12 to reduce its diameter is not limited to the above-mentioned embodiments. (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) can be applied with a pressurized fluid having 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, since the seal ring is incompressible and solid, even if it is deformed to reduce its diameter, the seal ring itself does not change in volume.
The entire ring is uniformly deformed in diameter in the circumferential direction, and wraps around the outer periphery of the rotating shaft to close the gap between the ring and the rotating shaft. Therefore,
The fluid pressurizing force applied to the back surface of the seal ring directly acts as a pressurizing force on the seal ring's rotating shaft without loss, and the pressurizing force is concentrated on the narrow protrusion, making it extremely effective in comparison to the pressurizing force. can exhibit high sealing power. Moreover, even if the rotating shaft is eccentric, the seal ring is displaced in the radial direction by the amount of eccentricity, and as described above, the narrow protrusion of the seal ring is uniformly distributed throughout the circumferential direction. By making a strong pressure contact, the specified shaft sealing function can be reliably and satisfactorily exerted. Furthermore, compared to the conventional structure in which pressurized fluid such as air is supplied and extracted from the hollow part of the seal member to expand and contract the seal member, the structure is simpler and the installation space is smaller. , it has the effect of being able to be made smaller.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the emergency shaft sealing device for a rotary shaft according to the present invention. FIG. 3 is a longitudinal side view showing the operating state when the rotating shaft is eccentric, and FIGS. 4A to 4E 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... Seal ring, 13... Pressing means, 15...
... Pressure contact surface, 16, 16a to 16e... Narrow protrusion portion.

Claims (1)

[Claims] 1 An emergency shaft sealing device for a rotating shaft that performs shaft sealing in place of the main shaft sealing device in the event of an emergency of the main shaft sealing device,
This emergency shaft sealing device for a rotating shaft has an annular storage groove formed in the inner circumference of the seal housing, along the outer periphery of the rotating shaft, with both side walls parallel to each other and perpendicular to the axis of the rotating shaft. A solid seal ring made of an elastic material and made of an incompressible material and whose inner diameter is larger than the outer diameter of the rotating shaft is placed in the storage groove between the rotating shaft and the inner peripheral surface of the seal ring. The seal ring is housed in a loosely fitted state with a gap smaller than (1/2) of the wall thickness of the seal ring, and is pressed against the seal housing side with pressurized fluid to press the seal ring against the rotating shaft. An emergency shaft sealing device for a rotating shaft, characterized in that a pressing means for compressing and deforming the diameter is provided, and a narrow protrusion protruding toward the circumferential surface of the rotating shaft is formed on the pressure contact surface of the seal ring. .