JPS6317897Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a stern tube shaft sealing device, and particularly aims to improve sealing performance against seawater and slurry resistance.

Conventionally, a mechanical seal has been used as a type of stern tube shaft sealing device, but
This type of shaft seal device has a structure in which the mechanical seal directly seals seawater and in-machine oil, so there is a risk that the sliding surface may be damaged by the slurry contained in the seawater, making it unstable. In addition to making it difficult to maintain a good seal, there is a risk that seawater may leak into the inside of the ship (bearings) or oil inside the ship may leak out of the ship.

In view of the above points, the present invention aims to improve the sealing performance and slurry resistance by arranging a limited leakage seal member on the outside (seawater side) of the mechanical seal, and in addition The system is constructed so that pressurized fluid is fed into the system, and the effective effect is achieved through the cooperation of these three parties.

Hereinafter, one embodiment of the stern tube shaft sealing device of the present invention will be described with reference to the drawings. In FIG. The sleeve 2 is attached to the opening of the shaft hole of the ship body 3 so as to seal between the sleeve 2 and the ship body 3 into which the shaft is inserted. 4 indicates a part of the propeller attached to the tip of the shaft.

In this stern tube shaft sealing device 1, a first casing 5 is fixed to the end surface of the ship body 3 via a gasket 6, and a second casing 5 is attached to the seawater A side of the first casing 5. (Adapter ring) 7. Third casing (Aft cover)
8 is airtightly fixed using an appropriate O-ring 9 or the like. On the inner peripheral surface of the second casing 7,
An annular recess 10 is formed by the second casing 7 and the first casing 5 closer to the inside of the machine, and a segment seal 11 as a limited leak seal is installed in the annular recess 10. This segment seal 11, which is divided into a plurality of parts in the circumferential direction, is tightened by a garter spring 12 fitted on the outer periphery and closely slides on the circumferential surface of the sleeve 2, and is also held by a coil spring 13 arranged inside the machine. Thus, it is brought into close contact with the wall surface 7a of the second casing 7. Note that each dividing element of the segment seal 11 is connected to the first or second casing 5, 7 by a pin (not shown) protruding from the first or second casing 5, 7.
It is prevented from rotating relative to 7. 14 is the second
and a lip seal sandwiched and fixed between the third casings 7 and 8, which includes a garter spring 15.
The pressure-receiving surface 14a, which has been tightened with the pressure-receiving surface 14a, faces the seawater A and slides closely against the outer periphery of the sleeve 2. A back-up spring portion 7b is provided on the back surface of the lip seal 14 of the second casing 7 to prevent excessive deformation of the lip seal 14. Reference numeral 16 denotes a mechanical seal disposed on the inner periphery of the shaft hole of the first casing 5 at a position close to the in-machine oil B, which is fitted into the stepped portion of the first casing 5 and is secured by an O-ring 18. A stationary sliding ring 17 that is kept airtight and is prevented from rotating with respect to the casing 5 by a pin (not shown), and a cover ring 19 that is fixed to the sleeve 2 by a pin (not shown).
and a rotating-side sliding ring 20 that is prevented from rotating by a pin (not shown) with respect to the cover ring 19 and rotates following the shaft. A sealing sliding surface 22 is formed on the contact surface with the moving ring 17. 2
3 is a segment seal 11 from the ship body 3 side.
A pressurized fluid feed line that feeds pressurized fluid toward an annular shaft hole space 24 formed between the main body 3 and the mechanical seal 16, and is a pressurized fluid feed line that feeds pressurized fluid from the ship body 3 through the first casing 5 to the space. A pipeline opening at 24 is disposed, and feeding equipment (not shown) is provided within the three ship bodies.

The stern tube shaft sealing device configured as described above uses the lip seal 14 and segment seal 11 arranged on the outside (seawater side) of the mechanical seal 16, and pressurized fluid to seal the mechanical seal 16 into seawater and seawater contained in the seawater. It is configured to prevent slurry from entering, and during sealing, the feeding device is operated as the original side to feed pressurized fluid. That is, firstly, the lip seal 14 and the segment seal 11 are responsible for preventing the leakage of seawater A, and especially the segment seal 1
1 is brought into pressure contact with the circumferential surface of the sleeve 2 and the wall surface 7a of the second casing 7 by the pressurized fluid introduced into the space 24 behind and on the outer periphery, thereby enhancing the sealing effect. Furthermore, when the pressure of the pressurized fluid reaches a certain level or higher for the segment seal 11, which is a limited leakage type, the pressurized fluid flows out toward the lip seal 14, but the pressurized fluid also balances with the seawater pressure. It becomes effective as a seal. When the space between the lip seal 14 and the segment seal 11 is filled with this pressurized fluid, the pressurized fluid applies back pressure to the lip seal 14, leaving the lip seal 14 in an idling state balanced with seawater pressure. Early wear, deformation, etc. due to sliding contact between the lip seal 14 and the sleeve 2 can be prevented. This lip seal 14 also functions as a dust seal to prevent foreign matter from entering the inside of the machine, but if the pressure of the pressurized fluid behind it decreases for some reason, it will be pushed by seawater pressure and , and automatically functions as the first seawater seal. Note that depending on the pressure, the pressurized fluid may expand the lip seal 14 and leak out of the ship. Therefore, it is recommended to use air, nitrogen gas, fresh water, etc. that will not cause problems such as pollution even if leaked into seawater. It is preferable to use Furthermore, the mechanical seal 16, which has improved sealing durability due to the above structure, can completely seal off the in-machine oil B.

Next, FIGS. 2 to 4 show the segment seal 1 as a limited leak type seal in the above embodiment.
1, an integral (not circumferentially divided) floating ring seal 25 (Fig. 2), an end face rubber seal 27 (Fig. 3), or a hollow pressure ring 30 (Fig. 4) may be used. ) is shown below. That is, the floating ring seal 25 shown in FIG.
The rotation is prevented by the coil spring 26.
The second casing 7 is pressed against the wall surface 7a of the second casing 7, and a minute gap is maintained between the sleeve 2 and the circumferential surface of the sleeve 2, thereby sealing the pressurized fluid in a limited leak type. Also, the end face type rubber seal 27 shown in FIG.
is externally fixed to the sleeve 2 by a garter spring 28, and the wall surface 7 of the second casing 7
A sealing sliding surface is formed between the surface and the surface to seal the fluid, and the flushing line 29 is connected from the second casing 7 side to the annular groove 27a formed on the surface. Open it. This flushing line 29 is the pressurized fluid feed line 2.
3, and the sliding surface is lubricated by using fresh water as the inlet fluid. A hollow pressurizing ring 30 shown in FIG. 4 is closely fitted between the first and second casings 5 and 7 so as to fill the annular recess 10, and is isolated from the pressurized fluid supply line 23 to the hollow portion 30a. Pressurized air is sent from a branched or separately piped line 31 to expand the sleeve 2 in the radial direction, so that it slides closely against the circumferential surface of the sleeve 2. When this pressurized hollow ring 30 is used, it is possible to change the state of close contact with the circumferential surface of the sleeve 2 by controlling the amount of pressurized air supplied, and adjust the amount of leakage of the pressurized fluid. Become. Further, wear resistance can be improved by constructing the inner peripheral surface of the hollow ring 30, which is usually made of synthetic rubber or the like, with a sliding material such as fluororesin.

As explained above, the stern tube shaft sealing device of the present invention has a limited leakage seal member placed outside the mechanical seal placed inside the vessel, and a pressure fluid that opposes the seawater pressure between the two seals. The system is designed to prevent seawater and the slurry contained in the seawater from reaching the mechanical seal, which prevents damage to the sliding surface of the mechanical seal due to the slurry and improves sealing performance. can be done. Furthermore, since the pressurized fluid is basically kept sealed between the two seals, even if some leakage occurs overboard, the consumption of the pressurized fluid can be minimized. With these features, the practical effects of the present invention are extremely large.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a half-cut sectional view of a stern tube shaft sealing device, and FIGS. 2 to 4 are sectional views of essential parts showing modifications of the same. 1...Stern tube shaft sealing device, 2...Sleeve, 3...
... Ship body, 4 ... Propeller, 5 ... First casing, 7 ... Second casing, 7a ... Wall surface, 8 ... Third casing, 10 ... Annular recess, 11 ... Segment seal, 12,15,2
8... Garter spring, 13, 21, 26...
Coil spring, 14...Lip seal, 16
... Mechanical seal, 17 ... Fixed side sliding ring,
19... Cover ring, 20... Rotating side sliding ring,
22... sealed sliding surface, 23... pressurized fluid feed line, 24... annular space, 25... integrated floating ring seal, 27... end face type rubber seal, 29... flushing line, 30... ...Hollow pressure ring, 30a...Hollow part.

Claims (1)

[Scope of utility model registration request] A case member having an annular shape is disposed around the outer periphery of the shaft, and a mechanical seal for axially sealing between the case member and the shaft circumferential surface is disposed at a position near the inside of the machine on the inner circumference of the case member. An annular recess is formed on the outer side of the mechanical seal, a limited leakage seal that slides on the shaft peripheral surface is fitted into the annular recess, and an annular space between the limited leakage seal and the mechanical seal is fitted. A stern tube shaft sealing device characterized by being provided with a pressurized fluid feed line that is open and feeds pressurized fluid.