JPH0512529Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a shaft sealing device used under high pressure conditions, which is equipped with a mechanism for reducing the pressure of the shaft sealing portion.

[Conventional technology]

Conventionally, mechanical seals have been widely used as shaft seal devices for rotating equipment such as pumps.

If the object to be sealed is high pressure, make sure that the high liquid pressure does not act directly on the mechanical seal.
The shaft seal is characterized by roughly dividing the high-pressure space inside the machine and the shaft seal space around the mechanical seal, and adjusting the pressure in the shaft seal space by flowing clear liquid at an appropriate pressure and flushing it. This is effective in maintaining good performance.

[The problem that the idea aims to solve]

However, in this case, it is important that the sealing means that partitions the high-pressure space and the shaft seal space around the mechanical seal be kept out of contact with the rotating shaft to avoid power loss due to friction. Despite the contact, it is necessary to have sufficient sealing performance to efficiently adjust the pressure reduction in the shaft seal space by flushing.

Therefore, the present invention was devised for the purpose of solving such problems.

[Means to solve the problem]

A shaft seal device according to the present invention includes a mechanical seal and a floating ring provided in a floating state between a housing and a rotating shaft on the high-pressure space side of the mechanical seal, and the mechanical seal is attached to the rotating shaft. a fixed mating ring, a non-rotating seal ring that is supported by a bellows so as to be freely movable in the axial direction and is in close contact with the mating ring from the opposite side of the floating ring, and this seal ring is concentric with the inner periphery of the housing. a support ring that supports the floating ring, and a notch that penetrates in the axial direction is formed in the support portion of the support ring, and is opened in the housing facing a space on the floating ring side from the support ring, and is connected to a suction means. a channel for extracting flushing liquid;
A flushing liquid supply guide hole is provided facing the space on the bellows side from the support ring.

[Effect]

The floating ring receives the pressure of the high-pressure space and the spring load, and the end face facing the mechanical seal is in close contact with the end wall of the collar, so no leakage occurs from this part. In addition, since there is no contact between the floating ring and the rotating shaft, leakage from the high pressure space to the shaft seal space occurs in this area, but since the floating ring is floating in the radial direction, the rotating shaft The gap between the mechanical seal and the shaft seal can be made extremely small, ensuring sufficient sealing performance, and the fluid pressure in the shaft seal space applied to the mechanical seal can be adjusted appropriately by the flushing fluid flowing through the guide hole. The mechanical seal can perform a good shaft sealing action.

〔Example〕

Next, one embodiment of the shaft sealing device according to the present invention is as follows.
This will be explained with reference to FIG.

1 is a housing of the pump, and 2 is a rotating shaft inserted into a shaft hole of the housing 1. Reference numeral 5 denotes a mechanical seal located near the outer end of the shaft hole and interposed between the housing 1 (seal cover 1') and the rotating shaft. A non-rotating seal ring 9 is airtightly supported via a retainer 8, and a flange 4 is airtightly supported via a packing 10 on a flange 4, which is integrated with a sleeve 3 externally mounted on the rotating shaft 2, and is connected to a pin 11. A mating ring 12, which rotates together with the rotating shaft 2 due to engagement, faces each other to form a sealed sliding portion 13. Reference numeral 14 denotes a support ring made of PTFE fixed to the inner periphery of the seal cover 1', and is attached to the outer periphery of the retainer 8 fitted with the seal ring 9 to prevent the seal ring 9 of the mechanical seal 5 from being eccentric due to the bending of the bellows 7. The retainer 8 slidably supports the surface and is in contact with the support ring 14.
A required number of notches 15 are formed on the outer circumferential surface of the holder to allow flow of flushing liquid, which will be described later.

Reference numeral 16 denotes a floating ring made of carbon that forms a non-contact sealing mechanism that divides the inside of the shaft hole of the housing 1 into a shaft seal space S1 around the mechanical seal 5 and a high pressure space S2 inside the pump; They are in a non-contact state with a slight gap G between them and the outer circumferential surface, and are not fixed in the radial direction. This floating ring 16 is secured by a metal ring 17 integrally joined to its outer circumferential surface engaging with a pin 20 protruding from a collar 19 fixed to the inner circumferential surface of the housing 1 using a set screw 18. a coil spring 2 supported by another collar 22 which is rotating and also engages the collar 19 via a pin 21;
3 from the high pressure space S2 side, the end surface 16a facing the mechanical seal 5 comes into close contact with the opposing end wall of the collar 19, forming a contact seal portion.

The housing 1 including the seal cover 1' has a conduit hole 24 for extracting the flushing liquid and a conduit hole 25 for supplying the flushing liquid. It opens facing the shaft seal side space S1 which is closer to the floating ring 16 than the contact part between the retainer 8 and the support ring 14 of No. The inner end of the hole 25 opens on the side opposite to the floating ring 16 with respect to the contact portion, that is, into the outer circumferential space of the bellows 7. The flushing liquid extraction conduit 24 is connected to a low-pressure part inside the machine (not shown) or to another suction pump outside the machine, and the flushing liquid supply conduit 25 is connected to a not-shown low-pressure part inside the machine or to another suction pump outside the machine, and a flushing liquid supply conduit 25 is used to store cooled clear flushing liquid. Not connected to a tank etc.

In the above configuration, the operation is explained as follows.
The floating ring 16 is pressed in the axial direction under the load of the coil spring 23 and the hydraulic pressure of the high pressure space S2, and the end surface 16 on the mechanical seal 5 side
Since part a is in close contact with the collar 19, there is no leakage from the high pressure space S2 through this part, but the inner peripheral surface of this floating ring 16 is not in contact with the outer peripheral surface of the sleeve 3 of the rotating shaft 2. Therefore, leakage through the gap G is allowed. However, since the floating ring 16, including the metal ring 17 joined to its outer peripheral surface, is not fixed in the radial direction, for example, the rotating shaft 2 rotates eccentrically with respect to the floating ring 16. In this case, the gap G is not uniform in the circumferential direction, and the dynamic pressure generated in the narrow part of the gap G becomes large, so that the floating ring 16 is pressed in the radial direction. , is supported floating so that it is always balanced at a position concentric with the rotating shaft 2. Therefore, it is not necessary to make the gap G large considering the eccentric movement of the rotating shaft 2. In other words, the gap G can be made extremely small. Even if the directional dimension is small, sufficient sealing performance can be obtained.

Further, a flushing liquid flows through a shaft seal space S1 that is roughly separated from the high pressure space S2 by a seal mechanism using the floating ring 16. More specifically, the flushing liquid in the shaft seal space S1 is sucked up and discharged from the guide hole 24, and the cooled and clear flushing liquid is transferred to the shaft seal space S1, which has a low pressure. It is designed to flow in from the hole 25. Therefore, this shaft seal space S1 is in a constant reduced pressure state, and the mechanical seal 5 is hardly affected by the hydraulic pressure in the high pressure space S2. The flushing liquid flowing from the guide hole 25 passes between the notch 15 of the retainer 8 and the support ring 14, and flows through the shaft seal space S1 into the guide hole 2.
4 side, absorbs the sliding heat generated in the sliding part 13 when passing the outer periphery of the sealing sliding part 13 of the mechanical seal 5, and also
Remove pollutants, etc. that leaked from the tank. In addition, an appropriate differential pressure is generated on both sides of the contact portion between the retainer 8 and the support ring 14 in the axial direction (slightly higher pressure on the guide hole 25 side), and the frictional force of the flushing liquid passing through the notch 15 is applied to the seal ring 9. mating ring 12
By adjusting the suction force from the flushing liquid extraction hole 24,
The surface pressure of the sealing sliding portion 13 of the mechanical seal 5 can be freely set, and a large differential pressure does not act on the bellows 7 from the outer periphery. Moreover, the shaft seal space S1 sealed by the sealing sliding surface 13 of the mechanical seal 5 is connected to the flushing liquid extraction guide hole 24.
Because it is maintained at a low pressure by suction from
The amount of flushing liquid leaking from the sealing sliding surface 13 can be extremely reduced.

[Effect of idea]

As described above, according to the present invention, a non-contact type sealing mechanism using a floating ring separates the shaft seal space from the high pressure space and maintains the shaft seal space at a low pressure by suctioning the shaft seal space. Therefore, high pressure does not act on the mechanical seal and its sealing sliding surface, and its sealing performance and durability can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view showing an embodiment of the shaft sealing device according to the present invention. DESCRIPTION OF SYMBOLS 1... Housing, 2... Rotating shaft, 3... Sleeve, 5... Mechanical seal, 13... Sealing sliding surface, 16... Floating ring, 16a...
... end face, 19 ... collar, 23 ... coil spring,
24, 25... Guide hole, G... Gap, S1... Shaft seal space, S2... High pressure space.

Claims (1)

[Scope of utility model registration request] It is equipped with a mechanical seal and a floating ring provided in a floating state between the housing and the rotating shaft on the high pressure space side of the mechanical seal,
The mechanical seal includes a mating ring fixed to a rotating shaft, a non-rotating seal ring supported movably in the axial direction by a bellows and in close contact with the mating ring from the opposite side to the floating ring, and this seal ring. a support ring concentrically supported on the inner periphery of the housing, a notch penetrating in the axial direction is formed in the support portion of the support ring, and a notch is formed in the housing on the floating ring side from the support ring. A shaft sealing device characterized by comprising a flushing liquid extraction conduit opened facing the shaft and connected to a suction means, and a flushing liquid supply conduit opened facing a space on the bellows side from the support ring.