JPH0341171Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to shaft seal technology, and is particularly used for shaft seals that require shaft sealing only when stopped and do not require shaft sealing during operation. This relates to a shutdown seal.

[Conventional technology]

Due to the structure of the equipment, the shaft seals of conventionally used self-priming vertical pumps generate shaft sealing pressure through the effects of back blades, etc. No mechanism is required and a simple dust seal is generally provided.

[Problem that the invention attempts to solve]

However, with the above-mentioned shaft seal structure with only a dust seal,
This method has the disadvantage that it cannot be used when the pump is stopped and pressure is applied to force the liquid into the shaft seal.

The present invention eliminates the above-mentioned drawbacks and provides a shutdown seal that performs a shaft sealing action only during stoppage, and opens the shaft seal portion during operation, in the shaft sealing portion where liquid pushing pressure is applied during stoppage. This is the purpose.

[Means for solving problems]

The shutdown seal according to the present invention is slidably and airtightly supported with an appropriate axial stroke on the housing side with respect to the sliding surface of the mating ring that is airtightly mounted on the rotating shaft. The sliding ends of the seal ring are separated and opposed to each other so as to be included in the stroke, and the seal ring is elastically biased toward the mating ring, and positive pressure is applied between the seal ring and the housing side member. An annular pressure chamber is formed by pressing the seal ring in a direction away from the mating ring against the pressing elasticity, and when the rotation shaft is driven, the annular pressure chamber is pressed against the pump, or The gist of this is to have a structure that applies positive fluid pressure from an external pressurizing device.

[Effect]

Therefore, the seal ring acts on and off the mating ring due to the relative pressure difference between the fluid pressure applied to the annular pressure chamber and the pressing elastic force, and when the seal ring is stopped, the fluid pressure in the annular pressure chamber disappears, the elastic pressing force prevails, and the seal ring slides toward the mating ring, and the liquid to be sealed with pressure enters the back pressure chamber of the seal ring, causing the seal ring to close to the mating ring. Maintains a shaft sealing state by coming into close contact with the bearing ring.

In addition, during driving, the positive pressure fluid applied from the driving pump or external device generates an opposite pressure in the annular pressure chamber that is greater than the elastic pressing force, so the seal ring is separated from the mating ring. Move back and maintain a non-contact situation.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a shutdown seal according to the present invention is applied to a shaft seal portion of a vertical pump will be described below with reference to the drawings.

FIG. 1 shows a sectional view of the shaft seal in a state where the pump is stopped, and FIG. 2 shows a sectional view of the shaft seal in a state where the pump is rotating.
Reference numeral 1 denotes a rotating shaft having a back blade b of a pump a attached to one end thereof, and the housing 5 side faces the sliding surface 2a of a mating ring 2 which is externally fitted onto the rotating shaft 1. A sliding end 4a of a seal ring 4 is airtightly supported in a shaft hole 3 formed in a shaft sealing portion of the shaft sealing portion. The mating ring 2 is airtightly inserted onto the small-diameter stepped portion 1a of the rotary shaft 1 via an O-ring 9, and fixed by a sleeve 6 fitted over the small-diameter stepped portion 1a. Further, the seal ring 4 has a large diameter portion 4c having a diameter D2 continuous to a small diameter portion 4b having a diameter D1 that constitutes the sliding end 4a, and a flange portion 7 at the end of the large diameter portion 4c. The shaft hole 8 is loosely fitted and externally inserted into the sleeve 6, and the small diameter portion 4b is airtightly slidable in the axial direction via the stomach of the O-ring 1 supported on the small diameter portion 3a of the shaft hole 3. The large diameter portion 4c is inserted airtightly and slidably in the axial direction via the O ring 12 supported on the large diameter portion 3b of the shaft hole 3, and the large diameter portion 4c is inserted between the inner wall of the shaft hole 3 and the outer periphery of the seal ring 4. An annular pressing chamber 10 is formed between them. Further, the seal ring 4 has a small hole 1 formed in the flange portion 7 in response to a detent pin 13 protruding from the step surface 3c of the large diameter portion 3c of the shaft hole 3.
4 is slidably extrapolated and rotation is prevented. The sliding stroke L2 of this part is the sliding end 4 of the seal ring 4 relative to the sliding surface 2a of the mating ring 2.
It is configured to have a larger backward stroke L1 than the backward stroke L1 of the locking pin 13, and is pressed in the direction of the arrow A by a coil spring 15 having an appropriate elastic force inserted between the head 13a of the locking pin 13 and the flange portion 7.
Reference numeral 16 designates a pressure supply path that opens between the O-rings 11 and 12 fitted in the shaft hole 3 and communicates with the annular pressure chamber 10 formed by diameters D1 and D2, The positive pressure fluid communicates with the positive pressure part of the coil spring 15 (arrow A) when the pump a is in operation.
Generates greater reverse pressure (arrow B).

The mating ring 2 and the seal ring 4 are made of a material having corrosion resistance and heat resistance, such as cemented carbide, silicon ceramic, carbon, or Teflon.
It is also possible to use a composite material in which only the sliding surface 2a and the sliding end 4a are made of these materials.

The shaft down seal with the above configuration is used for pump a
When stopped, the annular pressure chamber 10 as shown in FIG.
The pressing force (in the direction of arrow B) due to the fluid disappears,
The seal ring 4 slides in the direction of the mating ring 2 due to the pressing force (in the direction of arrow A) by the coil spring 15, and in addition to the pressing force, a liquid with pressure enters the chamber 7 of the flange portion of the seal ring 4. The sliding end 4a of the seal ring 4 touches the sliding surface 2a of the mating ring 2.
maintains a shaft-sealed state by being in close contact with the shaft.

Furthermore, when the pump a is driven, the positive pressure fluid W of the pump a is applied to the annular pressure chamber 10 via the pressure supply path 16 in the opposite direction (in the direction of the arrow B), which is greater than the pressing force (arrow A) by the coil spring 15. In order to generate pressure, the sliding end 4a of the seal ring 4 retreats from the sliding surface 2a of the mating ring 2 to maintain a non-contact state. At this time, negative pressure is generated in the chamber 7 of the flange portion of the seal ring 4 due to the action of the back blade b as the pump a is driven, and the liquid with the pressure that had entered when the pump was stopped is discharged. Therefore, it becomes a negative pressure gas state and does not require a shaft seal.

In addition, in the above embodiment, the positive pressure fluid W applied to the annular pressure chamber 10 was described using the output pressure of the driven pump, but the positive pressure fluid W can also be obtained from another pressurizing device. It is.

[Effect of idea]

As described above, the shutdown seal according to the present invention retracts the seal ring from the mating ring by the positive pressure fluid generated when the pump is driven, and when the pump is not driven, by stopping the fluid pressure. Since it has a structure in which the seal ring is elastically pressed against the mating ring, it has the feature that it can be implemented even in shaft seals where liquid pressure is applied during stoppage, and the practical effects of the present invention are as follows. Extremely large.

[Brief explanation of drawings]

The drawings show an embodiment of the shutdown seal according to the present invention, and FIG. 1 shows the pump in a stopped state;
FIG. 2 is a sectional view of each shaft seal portion in a rotating state of the pump. 1...Rotation axis, 2...Mating ring, 4
... Seal ring, 5 ... Housing, 10 ...
Annular pressure chamber, 13... anti-rotation pin, 15... coil spring, 16... pressure supply path, a... pump, b... back blade.

Claims (1)

[Scope of utility model registration request] The sliding end of the sealing ring, which is slidably and airtightly supported on the housing side with an appropriate axial stroke against the sliding surface of the mating ring airtightly mounted on the rotating shaft, Further, the seal ring is pressed and elastically biased toward the mating ring, and positive pressure is applied between the seal ring and the housing side member to cause the seal ring to resist the pressing elasticity. A shutdown seal comprising an annular pressure chamber formed by applying pressure in a direction away from a mating ring, and fluid pressure is applied to the annular pressure chamber when a rotation shaft is driven.