JPH0131817Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bellows-type mechanical seal related to shaft sealing technology.

[Conventional technology]

Conventionally, as shown in FIG. 3, the fixed ring 5
A bellows-type mechanical seal is used in which a primary seal portion is formed by closely sliding the bellows 54 between the fixed ring 52 and the housing 53 side, and a secondary seal portion is formed by interposing a bellows 54 between the fixed ring 52 and the housing 53 side.

[Problem that the invention attempts to solve]

However, in this type of bellows-type mechanical seal, when the bellows 54 is damaged, sealing liquid leaks from the secondary seal portion constituted by the bellows 54. However, since this leakage cannot be detected from the outside, the bellows 54 Damage could not be detected early, and sealing fluid leaked out, sometimes resulting in serious accidents.

The present invention was developed in view of the above problems, and is a bellows that detects the occurrence of leakage due to damage to the bellows and prevents the leakage of sealing liquid to the atmosphere, which would be fatal due to damage to the bellows. The purpose is to provide type mechanical seals.

[Means for solving problems]

The bellows-type mechanical seal of the present invention has a sleeve on the inner diameter of the secondary seal part constituted by the bellows, and detects breakage of the bellows by changes in internal pressure between the bellows and the sleeve. Therefore, the main purpose is to prevent leakage of the sealing liquid, and the primary seal part slides the fixed ring closely against the rotating ring that is airtightly inserted on the rotating shaft side, and the fixed ring and the housing side. In a bellows-type mechanical seal configured with a secondary seal part consisting of a bellows interposed in between,
A sleeve whose one end is airtightly fixed to the housing side is positioned between the bellows of the secondary seal portion and the rotating shaft, and the other end is slidably and airtightly inserted in the axial direction into the inner diameter of the fixed ring. At the same time, the pressure sensing means is connected to the annular space between the bellows and the sleeve.

[Effect]

In the bellows type mechanical seal described above, the pressure detection means is communicated with the annular space formed by the sleeve formed on the inner diameter of the bellows of the secondary seal part, so if the bellows is damaged, the seal will be removed from the damaged part. Liquid flows in, and the pressure sensing means detects an increase in pressure in the annular space to detect "breakage". At this time, the sealing liquid is prevented from flowing out to the atmosphere by the sleeve, so that the shaft sealing effect can be maintained.

〔Example〕

An embodiment of the bellows type mechanical seal of the present invention will be described below with reference to the drawings.
The figure is a front sectional view of the secondary seal portion.

Reference numeral 1 denotes a rotating ring which is fitted and fixed in an airtight manner to the shaft sealing portion of the rotating shaft 2, and a fixed ring 3 is slidably and closely attached to the rotating ring 1 from the axial direction to form a primary sealing portion. It consists of The fixed ring 3 is fitted and fixed to the end of an annular end plate 5 fixed to one end of the bellows 4, and is attached to the end of the housing 7 via a cylindrical holder 6 fixed to the other end of the bellows 4. A secondary seal is formed by being hermetically fastened and secured to the inner end of the shaft hole of a flange 8 fixedly attached to the shaft hole with bolts 9.
Reference numeral 10 denotes a sleeve inserted between the bellows 4 of the secondary seal portion and the rotating shaft 2, and one end of which is hermetically fixed to the shaft hole of the flange 8.
The other end is slidably and airtightly inserted in the axial direction into the shaft hole of the annular end plate 5 on which the fixed ring 1 is fixed via an O-ring 11, and an annular ring is inserted between the bellows 4 and the sleeve 10. It consists of space A. Also code 1
Reference numeral 2 denotes a pressure detection communication hole communicating with the annular space A, which communicates with a tank 13 formed outside the shaft sealing part via a pressure switch 14, a shutoff valve 15, and a throttle valve 16, and also communicates with a sealing liquid communication hole. The shaft sealing portion is filled with a sealing liquid at an appropriate pressure through the shaft sealing portion 17.

The bellows-type mechanical seal having the above structure performs a shaft sealing action by a primary seal portion formed between the sliding surfaces of the rotating ring 1 and the stationary ring 3 and a secondary seal portion formed by the bellows 4.

If the bellows 4 is damaged during use, the sealing fluid will leak from the damaged area to the bellows 4 and the sleeve 1.
In order to invade the annular space A between 0, the annular space A
Turn on the pressure switch 14 connected to the
It is possible to detect the occurrence of leakage. Furthermore, by closing the shutoff valve 15 when this leakage is detected, the sleeve 10 can prevent a large amount of sealing liquid from flowing out into the atmosphere, thereby avoiding serious accidents caused by leakage of the sealing liquid.

[Effect of idea]

As described above, the bellows-type mechanical seal of the present invention has a structure in which a sleeve is inserted into the inner diameter of the bellows to form an annular space, so that leakage of sealing liquid at the secondary seal due to breakage of the bellows can be easily detected. In addition, even if the bellows is damaged, the sleeve seals the sealing liquid that leaks from the damaged part of the bellows, thereby avoiding serious accidents caused by leakage of the sealing liquid. Yes, the practical effects of this invention are extremely large.

[Brief explanation of the drawing]

Figure 1 is a front sectional view showing an embodiment of the bellows type mechanical seal of the present invention, the detection section piping section, and the second
The figure is a front sectional view of the secondary seal portion, and FIG. 3 is a half-cut sectional view of the main part showing a conventional bellows type mechanical seal. 1... Rotating ring, 2... Rotating shaft, 3... Fixed ring,
4... Bellows, 7... Housing, 8... Flange, 10... Sleeve, 11... O-ring, 1
2... Communication hole for pressure detection, 14... Pressure switch, 15... Shutoff valve, 16... Throttle valve.

Claims (1)

[Scope of utility model registration request] It consists of a primary seal part that closely slides a fixed ring against a rotating ring that is airtightly inserted onto the rotating shaft side, and a secondary seal part that consists of a bellows interposed between the fixed ring and the housing side. In a bellows-type mechanical seal, a sleeve is positioned between the bellows of the secondary seal portion and the rotating shaft, with one end hermetically fixed to the housing side, and the other end slidable in the axial direction relative to the inner diameter of the fixed ring. A bellows-type mechanical seal characterized in that the bellows-type mechanical seal is airtightly inserted and a pressure detection means is communicated with the annular space between the bellows and the sleeve.