JPH0227730Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] The present invention relates to a shaft sealing technology for equipment, and more specifically, to a pressure equalization mechanism of a mechanical seal that prevents mutual leakage of two fluids.

Examples of mechanical seals that seal two fluids include those used in turbo drills that seal both the lubricating oil inside the machine and the muddy water that rotates the turbine. When the pressure and volume of (for example, muddy water) change and the pressure between the two fluids becomes unbalanced, the differential pressure acts on the fixed ring and rotating ring that make up the mechanical seal, causing the sliding state of both rings to change. changes and the sealing becomes unstable.
It was desired to devise an appropriate pressure equalization mechanism.

In view of this point, the present invention provides a pressure equalization mechanism for suppressing the influence on the sliding part of the mechanical seal due to relative pressure fluctuations of both fluids sealed together by the mechanical seal. With the goal.

[Structure of the idea]

To achieve this objective, the mechanical seal pressure equalization mechanism according to the present invention includes a mechanical seal that airtightly partitions a sealed space and other spaces around the shaft, an annular space formed inside a housing, and a mechanical seal that airtightly partitions a sealed space and other spaces around the shaft. a communication hole extending inside the housing from both ends in the axial direction and opening to each of the sealed space on one axial side of the mechanical seal and the space on the other axial side;
and an annular packing inserted into the annular space airtightly and slidably in the axial direction.

In the present invention, when a pressure difference occurs between the sealed space on one side and the space on the other side, which are airtightly partitioned by a mechanical seal, the pressure difference is transmitted to the annular space of the housing through the communication hole opening in each of the two spaces. The packing slides in the annular space toward the low pressure side in the axial direction, thereby contracting the volume on the low pressure side and expanding the volume on the high pressure side. This volume change absorbs the pressure difference between the sealed space and the other side space, and within a predetermined pressure change limit (which varies depending on the size of the annular space, the sliding range of the packing, etc.), the mechanical seal The pressures acting on both sides of the sliding part are almost balanced.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings.

Reference numeral 1 denotes a housing constituted by annular case members 2, 3, 4, and 5 hermetically joined to each other;
6 is a rotating shaft loosely inserted into the inner periphery of the shaft hole 1' of the housing 1, and 7 is a non-rotating fixing ring 8 that is airtightly supported and fixed to the inner periphery of the housing 1 (case member 3).
and rotates while being airtightly supported on the outer periphery of the rotating shaft 6,
This is a mechanical seal composed of a rotary ring 10 and the like that is biased by a spring 9 and slides closely against the fixed ring 8. An annular space 11 is formed between the case members 3 and 4 of the housing 1, and the annular space 11 has a plurality of communication holes 12, which are equally spaced in the circumferential direction and penetrate through each of the case members 3 and 4. 13, the housing 1 and the rotating shaft 6
The sealed space A, which is an oil chamber separated by the mechanical seal 7, and the space B on the other side, which is the muddy water side, are in communication with each other. Furthermore, in the annular space 11, the annular space 11 is connected to the space A.
An O-ring 14 is attached airtightly and slidably in the axial direction so as to separate the pressure receiving space a on the side and the pressure receiving space b on the side of the space B.

The above device is used, for example, as a shaft sealing device for a turbo drill, that is, the mechanical seal 7 and the O-ring 14 are used for both lubricating oil sealed in the space A and muddy water filling the space B and rotating a turbine (not shown). If the pressure of the muddy water in space B increases relatively, the increased pressure in space B that communicates with the inner peripheral side of the sealing sliding surfaces of fixed ring 8 and rotating ring 10 will be The rotary ring 10 is separated from the fixed ring 8 and acts in the direction of opening the sealing sliding surface, but at the same time, the pressure receiving space b in the annular space 11 into which the pressure of the space B is introduced through the communication hole 13 and the communication hole 12 Due to the pressure difference generated between the pressure receiving spaces a in the annular space 11 through which the pressure of the space A is introduced, the O-ring 14 moves the annular space 11 in a direction that contracts the volume of the pressure receiving space a, which has a relatively low pressure. Since it slides inside, the increased pressure is transmitted from the pressure receiving space a to the space A through the communication hole 12. Therefore, the muddy water pressure in the space B and the lubricating oil pressure in the space A are balanced with each other, and the differential pressure between the spaces A and B, which acts as an opening force on the sealing sliding surface of the mechanical seal 7, is eliminated. Furthermore, when the pressure of muddy water in space B decreases relatively, the O-ring 14 slides to the right in the figure, and as in the above case,
Since the pressure between the two spaces A and B is balanced by the pressure transmission, no pressure difference occurs in the rotating ring 10 from the space A side that would cause an excessive load on the sealing sliding surface.

Note that the pressure balancing ability according to this embodiment differs depending on the allowable amount of change in volume of the pressure receiving space a or b due to sliding of the O-ring 14, in other words, depending on the size of the annular space 11.

[Effect of idea]

As described above, in the pressure equalization mechanism of the mechanical seal according to the present invention, even if a relative pressure fluctuation occurs in the spaces on both sides of the mechanical seal, the packing in the annular space communicating with the spaces on both sides is able to compensate for the pressure fluctuation. By sliding according to the degree of pressure fluctuation, the pressure in the spaces on both sides is always the same, and no pressure difference that would cause surface opening or overload on the sliding surface of the mechanical seal occurs. Regardless,
Stable sealing surface pressure is maintained. Therefore, by implementing the pressure equalization mechanism of the present invention in a shaft seal under severe conditions such as a turbo drill where the pressure between both sealing fluids fluctuates relatively,
The sealing performance and durability of the mechanical seal can be greatly improved, and the conditions for designing and manufacturing the mechanical seal are extremely advantageous.

[Brief explanation of the drawing]

The drawing is a half-cut side sectional view showing an embodiment of the pressure equalizing mechanism of the mechanical seal according to the present invention. DESCRIPTION OF SYMBOLS 1... Housing, 1'... Shaft hole, 6... Rotating shaft, 7... Mechanical seal, 8... Fixed ring, 10... Rotating ring, 11... Annular space, 1
2, 13...Communication hole, 14...O ring, A, B
……space.

Claims (1)

[Scope of utility model registration request] A fixed ring airtightly supported on the inner periphery of the shaft hole of the housing, and a rotating ring that closely slides with the fixed ring and airtightly supported on the rotating shaft side, airtightly partitioning the sealed space and other spaces around the shaft periphery. a mechanical seal, an annular space formed inside the housing, extending inside the housing from both axial ends of the annular space, and each of the sealed space on one axial side and the space on the other axial side of the mechanical seal; 1. A pressure equalization mechanism for a mechanical seal, comprising a communication hole opening into the annular space, and an annular packing inserted airtightly and slidably in the axial direction into the annular space.