JP3813842B2 - Water lubricated stern tube sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water-lubricated stern tube sealing device.
[0002]
[Prior art]
As a stern tube sealing device used for a relatively small ship, for example, a water-lubricated stern tube sealing device described in Japanese Patent Publication No. 8-6818 is known.
This conventional stern tube sealing device includes a cylindrical casing in which a propulsion shaft is coaxially inserted and an inner / outer pair fixed to an inner peripheral portion of the casing so that a lip slidably contacting the propulsion shaft faces an outer side of the ship. And seal the back side of the outer seal ring by filling the chamber defined by the outermost seal ring and the innermost seal ring with lubricating water. The durability is improved.
[0003]
[Problems to be solved by the invention]
In the above conventional stern tube sealing device, since the lubricating water is only sealed without being pressurized in one chamber defined by the seal ring on the outside of the ship and the seal ring on the inside of the ship, The differential pressure from the ship's air pressure is always applied to the outermost seal ring, and the lubricating water is sealed in the chamber so that it cannot be replaced. The cooling effect on the seal ring is poor, and the seal ring is easily worn by frictional heat accompanying sliding on the propulsion shaft.
[0004]
For this reason, in the conventional stern tube sealing device, there is a high possibility that the seal ring on the outside of the ship will be damaged most with the increase of the draft pressure, and there is a problem in the durability of the sealing function in this point. There is a drawback that it is difficult to use for large-sized ships.
On the other hand, in the conventional stern tube sealing device, even if the outermost seal ring breaks, the next inner seal ring prevents leakage of outboard water into the ship to some extent. Since the back side of the seal ring is exposed to the space inside the ship, if the seal ring on the outside of the ship breaks, the seal ring on the inside of the ship is likely to break immediately.
[0005]
For this reason, with the conventional stern tube sealing device, once the seal ring on the outside of the ship fails, the sealing function for the rotating propeller shaft can no longer be effectively maintained, and the emergency inflatable seal is immediately activated to operate the system. Since it must be stopped, there is a problem with the durability of the sealing function during operation in this respect as well, and it has been difficult to use it for relatively large ships.
In view of such a situation, the present invention reduces the load on the outermost seal ring during operation and improves the cooling effect on the ring, and propulsion that rotates even if the outermost seal ring is damaged. An object of the present invention is to provide a water-lubricated stern tube sealing device that can maintain the sealing function for the shaft and can improve the durability of the sealing function during operation.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention takes the following technical means.
That is, according to the present invention, in the above-described water-lubricated stern tube sealing device, one or a plurality of intermediate seal rings fixed to the inner peripheral portion of the casing so that the lip faces the outer side of the ship is the outermost seal ring. The chamber is divided into a plurality of water-lubricating chambers arranged in the axial direction by disposing them between the innermost seal ring and the lubricating water in each of these water-lubricating chambers is pressurized at a pressure lower than the draft pressure. A water circulation circuit that circulates in the ship is provided, and this water circulation circuit includes a supply pipe that supplies lubricating water of the same pressure to each water lubrication chamber and a discharge pipe that discharges the lubricating water from each water lubrication chamber. A water supply circuit for supplying ship water higher than the draft pressure to the front side of the outermost seal ring, and a water supply branch pipe branched from the water supply circuit and having a normally closed first valve in the middle The most outboard Is connected to a water lubrication chamber on the back side of the seal ring, and a second valve that is normally open is provided on the supply pipe line leading to the lubrication chamber on the back side of the outermost seal ring. In addition, a normally open third valve is provided in a pipe line leading to the lubrication chamber on the back side of the outermost seal ring of the discharge pipe .
[0007]
In this case, since the lubricating water in each water lubrication chamber is pressurized by the water circulation circuit at a pressure lower than the draft pressure, the load on the outermost seal ring during operation is reduced. In addition, since the lubricating water in each water lubrication chamber circulates in the ship, even if the seal ring on the outermost side of the ship generates heat as it slides on the propulsion shaft, the frictional heat is transferred to the inside of the ship via the lubricating water. Heat is dissipated, thereby improving the cooling effect on the ring.
On the other hand, each water lubrication chamber includes an outermost seal ring, an innermost seal ring, and one or more intermediate seal rings fixed to the inner periphery of the casing so that the lip faces the outer side of the ship. Therefore, even if the seal ring on the outermost side of the ship is broken, leakage of outboard water to the inner side of the ship is prevented by one of the intermediate seal rings on the inner side of the ship.
[0008]
In this case, a water lubrication chamber defined by the intermediate seal ring and the intermediate seal ring on the inner side of the ship or the innermost seal ring on the inner side of the ship remains, and the back side of the intermediate seal ring on the outer side of the ship is on the water circulation circuit. Since the ring is filled with the pressurized lubricating water, the ring does not break immediately and the sealing function for the rotating propulsion shaft is effectively maintained.
Further, in the above-mentioned present invention, if each water lubrication chamber by water circulation circuit Let 's respectively to set the same pressure, the intermediate sealing ring is maintained in the idling state of no load during normal operation, most ship outside It is possible to prevent an unexpected situation that the intermediate seal ring does not function in an emergency where the seal ring is damaged.
[0009]
In the present invention, a water supply circuit for supplying ship water is provided on the front side of the outermost seal ring in the casing, and a water supply branch pipe branched from the water supply circuit and having a normally closed first valve is provided. It is connected to the water lubrication chamber on the back side of the outermost seal ring .
In this case, the first valve is set in a closed state during normal times when the outermost seal ring is healthy. If the first valve is opened when the seal ring is damaged, the inboard water sent from the water supply circuit can immediately apply pressure to the front side of the intermediate seal ring. The secondary leakage prevention function by the intermediate seal ring can be surely exhibited.
[0010]
Further, in the present invention, if an inflatable seal is provided in a portion on the outer side of the ship with respect to each seal ring in the inner peripheral portion of the casing, and a pressure circuit for pressing the seal against the propulsion shaft in an emergency is provided, It is possible to effectively cope with an emergency situation in which not only the outermost seal ring but also the intermediate seal ring is broken.
Furthermore, in the present invention, a tray for receiving lubricating water leaked from the innermost seal ring is fixed to the casing, and a recovery pipe for collecting the leaked water received by this tray in a water tank in the water circulation circuit is provided. If provided, the leaked water leaked from the respective seal rings to the inside of the ship can be used as lubricating water for the water circulation circuit.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the stern tube sealing device 1 of this embodiment includes a cylindrical casing 3 that is fixed to the rear tail of a hull (not shown) and that has a propulsion shaft 2 inserted coaxially therein, and its propulsion. A total of three seal rings 4, 5 and 6 fixed to the inner peripheral part of the casing 3 are provided so that the lip slidingly contacting the shaft 2 faces the outside of the ship.
Among these, the propulsion shaft 2 includes a hollow cylindrical shaft 7 and a sliding liner 8 that is spline-fitted to a portion corresponding to the inside of the casing 3 in the axially intermediate portion of the shaft 7. In the illustrated example, the lips of the seal rings 4, 5, 6 are brought into sliding contact with the sliding liner 8, but the liner 8 is omitted and the lips of the seal rings 4, 5, 6 are attached to the shaft 7. Direct sliding contact is also possible.
[0012]
The casing 3 includes a fixed cylinder 10 that is bolted to the inner side end of the base cylindrical body 9 projecting from the rear wall of the hull, and a bolt that is triple-plyed on the inner side end of the fixed cylindrical body 10. The holding ring 11 is fastened, and the outer peripheral edge of each of the seal rings 4, 5, 6 is fitted in a circumferential groove formed in the inner peripheral portion of the joint of each holding ring 11.
Further, a flange 12 is integrally formed on the inner peripheral surface of the fixed cylindrical body 10 located on the outer side of the ship relative to the seal rings 4, 5, 6 so that the inner peripheral edge is close to the shaft 7. And
An inflatable seal 13 is accommodated in a circumferential groove formed on the inner peripheral edge of the flange 12.
[0013]
Of the three seal rings 4, 5, 6, a first water lubrication chamber 14 is formed between the outermost outer seal ring 4 and the intermediate seal ring 5, and the intermediate seal ring 5 A second water lubrication chamber 15 on the inner side of the ship is formed between the inner seal ring 6 on the innermost side of the ship, and thereby, the chamber between the outer seal ring 4 and the inner seal ring 5 is aligned in the axial direction. It is divided into two water lubrication chambers 14 and 15.
The stern tube sealing device 1 of the present embodiment further includes a water circulation circuit 16 that circulates the lubricating water in the water lubrication chambers 14 and 15 in the ship while pressurizing the lubricating water at a pressure lower than the draft pressure, and the most in the casing 3. A water supply circuit 17 for supplying inboard water to the front side of the seal ring 4 on the outer side of the ship and a pressurizing circuit 18 for pressing the inflatable seal 13 toward the propulsion shaft 2 in an emergency are provided.
[0014]
As shown in FIG. 2, the water circulation circuit 16 includes a water tank 20 disposed in the ship, a supply pipe 21 for supplying lubricating water sucked up from the water tank 20 to the water lubrication chambers 14 and 15, A discharge pipe 23 for sending the lubricating water discharged from each water lubrication chamber 14, 15 to the gravity tank 22, and a return pipe 24 for returning the lubricating water overflowing from the gravity tank 22 to the water tank 20. I have.
A water pump 25 is provided in the middle of the supply pipe 21, and the portion of the supply pipe 21 that extends from the water pump 25 is bifurcated. Each branch pipe is connected to the first and second water lubrications. The chambers 14 and 15 are connected respectively. Further, the discharge pipe 23 is also provided with branch pipes connected to the first and second water lubrication chambers 14 and 15, respectively. These branch pipes are gathered together on the way and connected to the gravity tank 22. ing.
[0015]
The gravity tank 22 is disposed at a predetermined installation height H (about 2 m in the present embodiment) arbitrarily set from the axis of the propulsion shaft 2. The water pressure in the one water lubrication chamber 14 and the second water lubrication chamber 15 is set to be the same pressure.
As shown in FIG. 2, in the present embodiment, a tray 32 for receiving lubricating water leaked from the inner seal ring 6 inside the ship is fixed to the innermost holding ring 11 constituting the casing 3. The tray 32 is connected to a recovery line 33 for recovering leaked water to the water tank 20 in the water circulation circuit 16, thereby leaking from the seal rings 4, 5, 6 to the inside of the ship. Water is used as lubricating water for the water circulation circuit 16.
[0016]
On the other hand, the water supply circuit 17 includes a main pump (not shown) disposed in the ship and a water supply pipe 26 for feeding the ship water from the main pump into the casing 3. The water supply pipe 26 is connected to a bore formed in the fixed cylinder 10 of the casing 3, and supplies inboard water to the front side of the outer seal ring 4 in the casing 3.
A water supply branch pipe 27 is connected to the middle portion of the water supply pipe 26, and the water supply branch pipe 27 is a first water lubrication chamber 14 of two branch pipes constituting the discharge pipe 23 of the water circulation circuit 16. It is connected to the branch pipe that leads to The water supply branch pipe 27 is provided with a normally closed first valve 28, and the branch pipe leading to the first water lubrication chamber 14 of the supply pipe 21 is provided with a normally open second valve 29, A normally opened third valve 30 is provided on the branch pipe that leads to the first water lubrication chamber 14 of the discharge pipe 23.
[0017]
The pressurizing circuit 18 includes an unillustrated compressed air source (compressor) disposed in the ship, and an air supply conduit 31 that sends the compressed air from the air source into the circumferential groove portion in which the inflatable seal 13 is accommodated. I have. In addition, this pressurization circuit 18 may send in pressurized water instead of compressed air in a circumferential groove part.
Next, a shaft sealing method that can be performed by the stern tube sealing device 1 having the above-described configuration will be described together with its operation.
First, in this embodiment, the feed water pressure from the main pump of the feed water circuit 17 must be set higher than the draft pressure. Since the lubricating water supplied here flows out of the ship through the bearing gap, the water pressure measured in the ship is about 0.2 (kg / cm 2) higher than the draft pressure. The installation height H of the gravity tank 2 is set to about 2 m.
[0018]
In the normal operation in which the outer seal ring 4 is healthy, as shown in FIG. 2, the first valve 28 of the water supply circuit 17 is closed, and the water supply pressure from the water supply circuit 17 is reduced in the outer seal ring 4. The second valve 29 and the third valve 30 of the water circulation circuit 16 are opened, and the inside of the water lubrication chambers 14 and 15 is lower than the draft pressure by 0. The pressure is applied to 2 (kg / cm 2).
Thus, according to the stern tube sealing device 1 of the present embodiment, the lubricating water in each of the water lubrication chambers 14 and 15 is pressurized by the water circulation circuit 16 at a pressure (0.2 kg / cm 2) lower than the draft pressure. Therefore, the load on the outer seal ring 4 outside the ship during operation is reduced. Further, since the lubricating water in each of the water lubrication chambers 14 and 15 circulates in the ship through each pipe of the water circulation circuit 16, the outer seal ring 4 on the outer side of the ship generates heat as it slides on the propulsion shaft 2. However, the frictional heat is radiated to the inner side of the ship through the lubricating water, thereby improving the cooling effect on the ring 4.
[0019]
In the present embodiment, since the inside of each of the water lubrication chambers 14 and 15 is set to the same pressure during the normal operation, the intermediate seal ring 5 is maintained in an unloaded idling state. In an emergency where the outer seal ring 4 on the outside of the ship is damaged, an unexpected situation in which the intermediate seal ring 5 does not function is prevented in advance.
Next, when the outer seal ring 4 outside the ship is broken, the first valve 28 of the water supply circuit 17 is switched to the open state, and the second valve 29 and the third valve 30 of the water circulation circuit 16 are switched to the closed state. As a result, the water supply pressure from the water supply circuit 17 is also applied to the back side (the first water lubrication chamber 14) of the outer seal ring 4, and only the second water lubrication chamber 15 is pressurized by the water circulation circuit 16.
[0020]
In this case, the draft pressure outside the ship acts on the front side of the intermediate seal ring 5, but since the lip of the intermediate seal ring 5 is directed to the outside of the ship, the intermediate seal ring 5 causes the outboard water to flow to the inside of the ship. Leakage is prevented. The second water lubrication chamber 15 defined by the intermediate seal ring 5 and the inner seal ring 6 inside the ship remains, and the back side of the intermediate seal ring 5 is filled with lubricating water pressurized by the water circulation circuit 16. Therefore, the ring 5 is not damaged immediately, and the sealing function for the rotating propulsion shaft 2 is effectively maintained.
[0021]
In the present embodiment, when the outer seal ring 4 is damaged, the first valve 28 is opened, so that the inboard water sent from the water supply circuit 17 immediately applies pressure to the front side of the intermediate seal ring 5. Therefore, the secondary leakage prevention function by the ring 5 can be surely exhibited.
If the intermediate seal ring 5 is damaged, the inflatable seal 13 may be operated by the pressurizing circuit 18 to stop the entire system including the propulsion shaft 2.
[0022]
The present invention is not limited to the above embodiment. For example, the second water lubrication chamber 15 is set to a pressure higher than that of the first water lubrication chamber 14 using two gravity tanks having different heights. It may be.
Further, a plurality of intermediate seal rings 5 may be provided, and two or more water lubrication chambers may be provided.
[0023]
【The invention's effect】
As described above, according to the present invention, the load on the outermost seal ring during operation can be reduced and the cooling effect on the outer ring can be improved, and the outermost seal ring can be damaged. However, since the sealing function for the rotating propulsion shaft can be maintained, the durability of the sealing function during operation can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a seal structure of a stern tube sealing device according to the present invention.
FIG. 2 is a circuit configuration diagram of the apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stern tube sealing apparatus 2 Propulsion shaft 3 Casing 4 Outer seal ring 5 Intermediate seal ring 6 Inner seal ring 13 Inflatable seal 14 First water lubrication chamber 15 Second water lubrication chamber 16 Water circulation circuit 17 Water supply circuit 18 Pressurization circuit 20 Water Tank 27 Water supply branch pipe 27 First valve (open / close valve)
32 Tray 33 Collection line

Claims (3)

A cylindrical casing (3) in which a propulsion shaft (2) is coaxially inserted, and an inner peripheral portion of the casing (3) so that a lip slidably contacting the propulsion shaft (2) faces the outside of the ship. A plurality of fixed seal rings (4, 6) are provided, and lubricating water is filled in a chamber defined by the outermost seal ring (4) and the innermost seal ring (6). In the water lubricated stern tube sealing device,
One or a plurality of intermediate seal rings (5) fixed to the inner periphery of the casing (3) so that the lip faces the outer side of the ship are connected to the outermost seal ring (4) and the innermost seal ring. (6), the chamber is divided into a plurality of water lubrication chambers (14, 15) arranged in the axial direction, and the lubricating water in each of the water lubrication chambers (14, 15) is drawn. A water circulation circuit (16) that circulates in the ship while being pressurized at a pressure lower than the water pressure is provided. The water circulation circuit (16) supplies supply water of the same pressure to each of the water lubrication chambers (14, 15). A passage (21) and a discharge pipe (23) for discharging lubricating water from each of the water lubrication chambers (14, 15), and a draft pressure on the front side of the outermost seal ring (4). There is a water supply circuit (17) that supplies higher inboard water. A water supply branch pipe (27) branched from the water circuit (17) and having a normally closed first valve (28) is provided in the water lubrication chamber (14) on the back side of the outermost seal ring (4). A normally open second valve (29) is connected to the pipe line connected to the lubrication chamber (14) on the back side of the outermost seal ring (4) of the supply pipe (21). A normally open third valve (30) is provided in a pipe line that leads to the lubrication chamber (14) on the back side of the outermost seal ring (4) of the discharge pipe (23). and water-lubricated stern tube sealing apparatus, characterized in that are. An inflatable seal (13) is provided on the outer side of each seal ring (4, 5, 6) in the inner peripheral part of the casing (3) to press the seal (13) against the propulsion shaft in an emergency. The water-lubricated stern tube sealing device according to claim 1, wherein a pressure circuit (18) is provided. A tray (32) for receiving lubricating water leaked from the innermost seal ring (6) is fixed to the casing (3), and the leaked water received by the tray (32) is passed through the water circulation circuit (16). The water-lubricated stern tube seal device according to claim 1 or 2 , wherein a recovery conduit (33) for recovery is provided in the water tank (20).

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