JP5123371B2 - mechanical seal - Google Patents

Description

  The present invention relates to a mechanical seal.

  The general rule of the mechanical seal that seals the gap between the rotating shaft and the housing is defined in JIS-B2405. The mechanical seal is fitted to the outer periphery of the rotating shaft and is hermetically attached to a sleeve that rotates together with the rotating shaft. The mechanical seal is hermetically attached to a rotating ring that rotates together with the sleeve and a seal cover that is fixed to the housing. And having a ring. The rotating ring and the fixed ring are in sliding contact with each other on a sliding surface perpendicular to the shaft, one of which is a mating ring that does not move in the axial direction, and the other is movable in the axial direction and spring-biased mating. It is a seal ring pressed against the ring.

  In the mechanical seal, a shaft seal fluid such as lubricating oil is present on the sliding surface, so that the clearance between the sliding surfaces is completely sealed. If the temperature of the sliding surface rises due to friction between the rotating ring and the stationary ring, the shaft seal fluid may deteriorate, or impurities such as process gas dissolved in the shaft seal fluid may denature, resulting in solid deterioration. is there. When such a deteriorated material adheres to the sliding surface, it causes damage called blistering on the sliding surface. In addition, when the deteriorated material adheres to the periphery of the sliding surface, it forms a secondary sliding surface that pseudo-expands the sliding surface to reduce the contact pressure between the rotating ring and the stationary ring, and seal the mechanical seal. There is a problem of losing ability.

  In order to prevent the generation of deteriorated products, it is effective to reduce the calorific value by reducing the pressure contact force between the rotating ring and the stationary ring or by reducing the sliding contact area between the rotating ring and the stationary ring. As a result, there is a problem that the shaft sealing ability is lowered.

  In addition, in order to efficiently cool the rotating ring and the stationary ring with the shaft seal fluid, for example, as described in Patent Document 1, a method of providing a shaft seal fluid channel called hydrocut is known. Yes. However, this method has a problem that the amount of leakage of the shaft seal fluid to the low pressure side increases.

  Patent Document 2 discloses an invention for forcibly supplying a quenching fluid such as steam around a sliding surface for cooling. However, in order to supply the quenching fluid, an incidental facility is required, and an increase in cost is inevitable.

JP 2004-293765 A JP 2003-74712 A

  Then, in view of the said problem, this invention makes it a subject to provide the mechanical seal | sticker in which the deteriorated material produced | generated on the sliding surface does not accumulate.

In order to solve the above problems, a mechanical seal according to the present invention extends a sleeve that rotates with a shaft, a seal cover fixed to a housing through which the shaft passes, and an outer side of the seal cover so as to surround the sleeve. An outer cover; a rotating ring attached to the sleeve; and a fixed ring attached to the seal cover and in sliding contact with a sliding surface perpendicular to the rotating ring and the shaft, the outer cover and the sleeve The outer cover seals a space formed by the sleeve, the rotating ring, the fixed ring, and the seal cover to form a sealed space, and a solvent is formed in the sealed space. or an inert gas is sealed, the rotating ring and there is lubricating shaft sealing fluid to the sliding surface of the fixed ring, high professional than the internal pressure of the sealed space The Sugasu shall seal the interior of the housing.

  According to this configuration, it is possible to prevent the shaft seal fluid and impurities from being oxidized by the inert gas and suppress the generation of the deteriorated material, or to prevent the deteriorated material from being dissolved and deposited by the solvent. Thereby, the pressure contact force of the sliding surface does not change, and the shaft sealing ability does not decrease.

  As described above, according to the present invention, the deteriorated material is not deposited on the inner edge of the sliding surface of the mechanical seal, so the shaft sealing ability is not lowered.

It is sectional drawing of the mechanical seal of 1st Embodiment of this invention. It is sectional drawing of the mechanical seal of 2nd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Mechanical seal 2 Rotating shaft 3 Housing 4 Sleeve 5 Seal cover 6 Rotating ring (mating ring)
7 Fixed ring (seal ring)
8 O-ring 9 Sliding surface 10 Spring 15 External cover 16 Lip seal 17 Sealed space

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows a mechanical seal 1 according to a first embodiment of the present invention. The mechanical seal 1 seals a gap between the rotating shaft 2 and the housing 3 through which the rotating shaft 2 passes. The mechanical seal 1 is fitted to the outer periphery of the rotary shaft 2, rotates with the rotary shaft 2, fixed to the housing 3, and fixed to the stationary seal cover 5, and fixed to the outer periphery of the sleeve 4. A rotating ring (mating ring) 6 that rotates, and a fixed ring (seal ring) 7 that is slidable in the axial direction but non-rotatably attached to the seal cover 5.

  The rotating shaft 2, the sleeve 4, and the rotating ring 6 are airtightly fixed to each other by an O-ring 8, and the housing 3, the seal cover 5, and the fixing ring 7 are also airtightly fixed to each other by the O-ring 8. The rotating ring 6 and the fixed ring 7 are in sliding contact with each other at a sliding surface 9 perpendicular to the rotating shaft 2. The fixed ring 7 is urged in the direction of the rotating ring 6 by a spring 10 and is pressed against the rotating ring 6 with a predetermined force by a sliding surface 9.

  Further, the mechanical seal 1 is provided with an outer cover 15 extending so as to surround the sleeve 4 on the outside of the seal cover 5, and a lip seal 16 is disposed between the outer cover 15 and the sleeve 4. The outer cover 15 seals the space formed by the sleeve 4, the rotating ring 6, the stationary ring 7 and the seal cover 5 to form a sealed space 17, and a solvent (for example, an alcohol-based solution) is contained in the sealed space 17. ) Is enclosed.

Then, the effect | action of the mechanical seal 1 which consists of the above structure is demonstrated.
The mechanical seal 1 seals process gas having a pressure higher than that of the outside existing inside the housing 3 (left side in the drawing) inside the housing 3. Since the rotary shaft 2, the sleeve 4, and the rotary ring 6 are hermetically sealed by the O-ring 8, and the housing 3, the seal cover 5, and the stationary ring 7 are also hermetically sealed, the process gas flows between the rotary ring 6 and the stationary ring 7. It is possible to flow out to the atmosphere through the gap between the sleeve 4 and the seal cover 5 only from the gap between the sliding surfaces. The spring 10 presses the stationary ring 7 against the rotating ring 6 so that the gap between the sliding surfaces 9 does not become large. Further, a shaft seal fluid such as lubricating oil is supplied to the sliding surface 9 so that the sliding surface 9 slides. A slight gap in the moving surface 9 is sealed. As a result, the mechanical seal 1 slightly leaks the shaft seal fluid from the sliding surface 9 into the gap between the sleeve 4 and the seal cover 5, but does not allow the process gas in the housing 3 to leak outside.

  In the mechanical seal 1, frictional heat is generated by the sliding contact between the rotating ring 6 and the fixed ring 7, so that impurities of the lubricating fluid may be denatured by the heat to produce a solid deterioration product. The generated deteriorated material leaks from the sliding surface 9 together with the shaft seal fluid to the inside where the pressure is low (between the sleeve 4 and the seal cover 5). The deteriorated material leaking from the sliding surface 9 is dissolved by the solvent, so that the secondary sliding surface is not formed and the shaft sealing ability is not lowered. The lip seal 16 does not have a strong sealing ability like the sliding surface 9, and the solvent leaks out from the lip seal 16 little by little. Therefore, it is necessary to add the solvent appropriately.

  Instead of the lip seal 16, another sealing method such as a segment seal may be used. Moreover, you may provide the apparatus which circulates a solvent.

Further, FIG. 2 shows a mechanical seal 1 according to a second embodiment of the present invention.
In the mechanical seal 1 of the present embodiment, an inert gas (for example, nitrogen) is supplied to the sealed space 17 sealed with the external cover 15. The inert gas is released into the atmosphere from the gap between the sleeve 4 and the outer cover 15.

  In the present embodiment, the supply of oxygen to the shaft seal fluid of the sliding surface 9 can be shut off, and the oxidation of impurities can be prevented to suppress the generation of deteriorated products.

Claims (1)

A sleeve that rotates with the shaft;
A seal cover fixed to a housing through which the shaft passes;
An outer cover extending outside the seal cover so as to surround the sleeve;
A rotating ring attached to the sleeve;
A fixed ring attached to the seal cover and in sliding contact with the rotating ring and a sliding surface perpendicular to the axis;
A seal is disposed between the outer cover and the sleeve, and the outer cover seals a space formed by the sleeve, the rotating ring, the fixed ring, and the seal cover to form a sealed space. , A solvent or an inert gas is sealed in the sealed space ,
A lubrication shaft sealing fluid exists on the sliding surface of the rotating ring and the stationary ring, and a process gas having a pressure higher than the pressure inside the sealed space is sealed inside the housing. mechanical seal.

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