JPS6146287Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a leakage prevention device for a mechanical seal.

As is well known, for conventional mechanical seals, the sealing load is fixedly determined by the design specifications of the mechanical seal and the conditions of the rotating equipment such as the pump to which it is attached. It is virtually impossible to predict this and adjust the load force acting on the sealed end face from the outside.

Therefore, the load force acting on the sealed end face is drastically reduced due to changes in the operating conditions of the rotating equipment, etc., and a large amount of fluid leaks from the sealed end face, resulting in a state in which the mechanical seal is unable to perform its sealing function at all. The reality is that even when it happens, it is impossible to prevent it from happening.

This invention was developed in view of the above-mentioned circumstances. When the amount of fluid leaking from the sealed end surface becomes too large to perform the sealing function, this invention is detected in advance and the sealing load is adjusted externally. In addition, the present invention provides a novel leakage prevention device for a mechanical seal that is devised to maintain the sealing function of the mechanical seal well.

Next, an example thereof will be explained with reference to the drawings. This embodiment relates to an example in which the present invention is applied to a mechanical seal attached to a pump.

In the figure, 1 is a seal housing, 2 is a rotary shaft extending from the pump chamber and penetrating through the seal housing 1, and 3 and 4 are rotating seal rings and stationary seals disposed in the seal housing 1, respectively. It is a ring. The rotating sealing ring 3 is fitted and fixed to the rotating shaft 2, and the stationary sealing ring 4 is supported by a sleeve 5 that is fitted onto the rotating shaft 2 so as to be movable in the axial direction. The rotary ring 3 is also biased by a compression coil spring 7 interposed between the rotary ring 3 and a seal case 6 attached to the rotary ring 3. Note that 8 is a nut screwed onto the rotating shaft 2.

A main sealed chamber 10 is formed in the seal housing 1 so as to face the sealed end surfaces 9 of the rotating sealing ring 3 and the stationary sealing ring 4. This main sealed chamber 10 is communicated with a sealed fluid side 12, which is the suction side of the pump chamber, via a communication passage 11 formed between the seal housing 1 and the rotating shaft 2.
Further, in a portion of the seal housing 1 that substantially opposes the sealed end surface 9, a high pressure source of the pump, such as a discharge port 1, is provided.
4 is connected to the main sealed chamber 10 through a communicating pipe 15 and has an inflow hole 13 that opens into the main sealed chamber 10 . The fluid thus released is discharged to a sealing fluid side 12 which is a low pressure side, and the sealing end face 9 is cooled during this time.

Also, a first sub-sealing ring, which is independent of the main sealed chamber 10, is provided facing the back side of the sealing ring on the side that applies a load force to the sealing end face 9, that is, the stationary sealing ring 4, among the two sealing rings 3, 4. A sealed chamber 16 is formed. That is, this first sub-sealed chamber 16 is connected to the stationary sealing ring 4
A sealed space surrounded by the seal housing 1, stationary seal ring 4, and seal case 6 is formed by sealing between the seal housing 1 and the seal case 6 using O-ring packings 17 and 18. , a fluid at a predetermined pressure is supplied by a fluid supply mechanism 29, which will be described later.

Therefore, the fluid pressure acting in both sealed chambers 10 and 16 causes a predetermined load force to be applied to the sealed end face 9, thereby sealing the sealed fluid side 12 from the atmospheric side 19. being done. In this sealed state, the fluid in the main sealed chamber 10 lubricates the sealed end surface 9.

Furthermore, there is a space between the sleeve 5 and the seal case 6 that is connected to the leak passage 23 which is a gap formed between the stationary seal ring 4 and the sleeve 5, and is independent of both the sealed chambers 10 and 16. A second sub-sealed chamber 24 is formed, and fluid leaking from the sealed end face 9 is guided into the second sub-sealed chamber 24 through the leak passage 23. In addition, 2
Reference numeral 5 denotes a mechanical seal interposed between the sleeve 5 and the seal case 6. The stationary seal ring 26 is attached to the seal case 6, and the stationary seal ring is slidably fitted onto the sleeve 5 and is connected to the stationary seal ring by a compression coil spring 27. 26 and a rotary sealing ring 28 which is biased to press the second sub-sealed chamber 24 to the atmosphere side 19.
It is to be sealed from

Further, a fluid supply mechanism 29 that supplies fluid into the first sub-sealed chamber 16 and can adjust the fluid pressure, a pressure detection mechanism 30 that detects the pressure within the second sub-sealed chamber 24, and a 2 sub-sealed chamber 24
First, the fluid supply mechanism 29 is provided with a control mechanism 31 that controls the fluid supply mechanism to adjust the difference between the fluid pressures in the sealed chambers 10 and 16 to a set differential pressure according to the pressure inside the sealed chambers 10 and 16. I will explain about it.

That is, a supply pump 32 separate from the pump to which the mechanical seal is attached, which is operated to keep the discharge pressure constant at all times, is provided, and this supply pump 3
The second suction pipe 33 is led to a suitable water source 34, and the discharge pipe 35 is branched, and one branch pipe, a supply pipe 35a, is formed in the seal housing 1 and opens into the sub-sealed chamber 16. Inflow hole 36
The reflux pipe 35b, which is the other branch pipe, is connected to the water source 34, and the reflux pipe 35b is connected to the water source .
A pressure regulating valve 37 is provided at b.

Therefore, according to this fluid supply mechanism 29,
Fluid is supplied from the discharge pipe 35 to the sub-sealed chamber 16 via the supply pipe 35b and the inflow hole 36, and surplus fluid is returned to the water source 34 from the reflux pipe 35b, so the supply pump 31 is operated at a constant discharge pressure. In conjunction with this, the fluid pressure within the sub-sealed chamber 16 is maintained at a constant pressure. By operating the pressure regulating valve 37 to adjust the pressure of the fluid flowing into the reflux pipe 35b, the fluid pressure within the sub-sealed chamber 16 can be increased or decreased.

Further, the pressure detection mechanism 30 includes a pressure tank 39 connected to the second sub-sealed chamber 24 via a communication path 38 formed in the seal case 6.
A pressure switch 41 equipped with a safety valve 40 is attached to 9, and the amount of fluid flowing out from the sealed end face 9 is detected by pressure.

That is, in a proper lubrication state in which the amount of fluid leaking from the sealed end face 9 is within a predetermined allowable range, the pressure tank 39 contains an amount corresponding to the amount of fluid that can flow into the second sub-sealed chamber 24 from the sealed end face 9. An orifice 42 is provided for discharging the fluid in the pressure tank 39 to a suitable discharge tank, such as the water source 34. Therefore, the orifice 42 maintains the water level in the pressure tank 39, that is, the pressure in the pressure tank 39, which is the pressure in the second sub-sealed chamber 24, at a predetermined set pressure. Note that this set pressure is set to be an appropriate amount lower than the pressure inside the main sealed chamber 10, and the mechanical seal 25 is designed so that it can exhibit a sufficiently good sealing function not only at this set pressure but also under higher pressures. It is configured.

The pressure switch 41 has a sealed end face 9
When the amount of leakage is within the allowable range (the range of leakage amount when proper lubrication is performed), that is, when the pressure in the pressure tank 39 is maintained at the set pressure, it is held in the OFF state. It is configured to be turned on when the amount of leakage exceeds the allowable range and the water level, that is, the pressure in the pressure tank 39 exceeds the set pressure.

Therefore, this pressure detection mechanism 30 operates the pressure switch 41 on and off in order to detect whether the amount of fluid leaking from the sealed end face 9 exceeds the permissible range based on the pressure inside the pressure tank 39. It is.

Furthermore, the control mechanism 31 includes a differential pressure transmitter 43
and a controller 44. Differential pressure transmitter 43
is interposed in a connecting pipe 45 that connects the communication pipe 15 and the supply pipe 35a, and both pipes 15, 35a are connected to each other.
The difference in the pressure inside the pipe, that is, the difference in the fluid pressure in both the sealed chambers 10 and 16 is detected, and the differential pressure value data is inputted to the controller 44.

Then, the controller 44 controls the pressure switch 41
ON-OFF control is performed by the ON-OFF of
The pressure regulating valve 37 is adjusted and controlled so that the differential pressure of 0 and 16 becomes the set differential pressure, and the first sub-sealed chamber 16
It automatically adjusts the fluid pressure inside the tank. Note that this set differential pressure is calculated from the total axial pressure that the stationary seal ring 4 receives from the fluid in the first sub-sealed chamber 16 to the total axial pressure that the stationary seal ring 4 receives from the fluid in the main sealed chamber 10 (sealed end surface 9 The differential pressure is set at which the total pressure (including the total pressure applied to the seal), that is, the load force acting on the sealing end face 9 exhibits the best sealing function.

Next, the operation of the leakage prevention device according to the present invention will be explained with reference to the above embodiment.

In a sealed state in which the load force acting on the sealed end face 9 is appropriate and the sealed end face 9 is properly lubricated, the amount of fluid leaking from the sealed end face 9 is within the permissible range. The fluid in the pressure tank 39 is discharged from the orifice 42 by an amount corresponding to the amount of fluid flowing into the second sub-sealed chamber 24 from the second sub-sealed chamber 9, and the pressure in the second sub-sealed chamber 24, that is, the pressure tank 39, reaches the set pressure. is held and pressure switch 4
1 is kept in the OFF state.

However, if, for example, the fluid pressure in the main sealed chamber 10 increases due to changes in pump operating conditions and the load force acting on the sealed end face 9 decreases below the allowable load force, the sealing function is impaired and the sealed end face 9 An unacceptable amount of fluid begins to leak.

In such a leakage state, the orifice 42
Since the amount of fluid discharged from the pressure tank 39 does not increase above a certain level, the water level in the pressure tank 39 rises, that is, the pressure in the pressure tank 39 rises above the set pressure, and the pressure switch 41 is turned on. Controller 44 is activated.

Then, based on the data inputted by the differential pressure transmitter 43, the pressure regulating valve 37 is adjusted and controlled by the controller 44 so that the differential pressure between the two sealed chambers 10 and 16 becomes the set differential pressure. The fluid pressure within the first sub-sealed chamber 16 is adjusted.

When the differential pressure between the sealed chambers 10 and 16 is adjusted to the set differential pressure, the load force acting on the sealed end face 9 is appropriately increased and adjusted, and a large amount of leakage from the sealed end face 9 is prevented. A good sealing function by the sealing end face 9 is now exhibited.

When the sealed state is restored, the amount of leakage from the sealed end face 9 falls within the allowable range, the fluid in the pressure tank 39 is gradually discharged from the orifice 42, and the pressure in the pressure tank 39 is set again. The pressure is returned to normal, the pressure switch 41 is turned off, and the operation of the controller 44 is stopped.

Therefore, if the amount of leakage from the sealed end face 9 exceeds the level of lubrication, this can be detected by the pressure in the second sub-sealed chamber 24 and the load force on the sealed end face 9 can be adjusted to be appropriate. , a good sealing function is always maintained.

Note that the leakage prevention device according to the present invention is not limited to the above-mentioned embodiments. For example, the leakage prevention device according to the present invention is not limited to the above-mentioned embodiment. Alternatively, the discharge pressure may be adjusted, thereby increasing or decreasing the fluid pressure within the first sub-sealed chamber 16. In this case, the control mechanism 31 controls the rotation speed of the supply pump 32.

Further, the pressure detection mechanism 30 detects the amount of leakage from the sealed end face 9 using the pressure in the second sub-sealed chamber 24, but this pressure, that is, the pressure in the pressure tank 39, is not detected by the pressure switch 41. The water level in the pressure tank 39 may be detected using an electrode rod or the like. In other words, the controller 44 of the control mechanism 31 is turned on and off in response to fluctuations in the water level of the pressure tank 39.
You may also do so.

Furthermore, the control mechanism 31 may not be fully automatic as in the embodiment described above, but may be partially or entirely manual. For example, pressure detection mechanism 3
0, the second sub-sealed chamber 24 (or pressure tank 39)
A pressure detector capable of detecting the internal pressure may be attached to the controller 44, and the controller 44 may be manually turned on and off by visually detecting the pressure detector. Alternatively, the controller 44 may be eliminated, and a differential pressure detector may be provided in the connecting pipe 45 in place of the differential pressure transmitter 43, and the pressure may be determined while visually detecting the differential pressure detector and the pressure detector. Adjustment valve 3
7 may be manipulated artificially.

The components of the fluid supply mechanism 29, pressure detection mechanism 30, and control mechanism 31 described above are all conventionally known.

Furthermore, the leakage prevention device according to the present invention can be applied not only to mechanical seals attached to pumps as in the above embodiments, but also to mechanical seals attached to all other rotating equipment. The present invention can also be applied to a mechanical seal of the type in which one sealing ring 3 is rotated and the other sealing ring 4 is stationary in the above embodiment. Further, the first sub-sealed chamber 16 is not sealed with O-ring gaskets 17 and 18 as in the previous embodiment;
It is also possible to form the second sub-sealed chamber 24 using a metal bellows or the like, and the second sub-sealed chamber 24 is not limited to being formed as in the above embodiment.

In any case, as is clear from the above explanation, according to the mechanical seal leakage prevention device of the present invention, whether or not the amount of leakage from the sealed end face exceeds the permissible range is detected in the second sub-sealed chamber. This can be predicted by detecting pressure fluctuations in the sealed end surface, and by making it possible to adjust the fluid pressure in the first sub-sealed chamber, the load force acting on the sealed end surface can be adjusted from the outside, so the load force acting on the sealed end surface is drastically reduced. If a situation occurs in which the amount of leakage from the sealed end face exceeds the level of lubrication, the load force can be adjusted appropriately to prevent abnormalities such as a large amount of leakage from the sealed end face, which may impair the sealing function. It is possible to prevent such a situation from occurring, and the good sealing function of the mechanical seal can be maintained for a long period of time.

[Brief explanation of the drawing]

The figure is a schematic longitudinal sectional view showing an embodiment of the mechanical seal leakage prevention device according to the present invention. 3... Rotating sealing ring, 4... Stationary sealing ring, 9... Sealing end surface, 10... Main sealed chamber, 12... Sealing fluid side, 16...
First sub-sealed chamber, 24... Second sub-sealed chamber, 29... Fluid supply mechanism, 30... Pressure detection mechanism, 31... Control mechanism.

Claims (1)

[Scope of utility model registration request] A main sealed chamber facing the sealed end faces of the stationary sealing ring and the rotating sealing ring and connected to the sealed fluid side, and facing the back side of one of the sealing rings that applies a load force to the sealed end face. a second sub-sealed chamber, which forms a first sub-sealed chamber independent of the main sealed chamber, and a second sub-sealed chamber which is independent of the main sealed chamber and the first sub-sealed chamber and into which fluid leaking from the sealed end surface can flow; A fluid supply mechanism is provided to supply fluid into the first sub-sealed chamber and to change the fluid pressure, and the amount of leakage from the sealed end surface is determined by the pressure in the second sub-sealed chamber. A pressure detection mechanism is provided to detect the pressure in the second sub-sealed chamber, and the difference between the fluid pressures in the main sealed chamber and the first sub-sealed chamber is adjusted to a set differential pressure according to the pressure in the second sub-sealed chamber detected by the pressure detection mechanism. A leakage prevention device for a mechanical seal, characterized in that a control mechanism is provided to control the fluid supply mechanism.