JP2022181469A - Bow side sealing structure of stern tube and vessel - Google Patents

Abstract

To make it possible to detach a seal liner from a propeller shaft in a state with the propeller shaft left as it is in a bow side sealing structure of a stern tube provided on a vessel.SOLUTION: A bow side seal structure 10 of a stern tube 5 provided on a vessel and causing a propeller shaft 1 to go through from an engine room in a hull to the outside of the hull includes: a seal liner 11 attached on the outer periphery surface of the propeller shaft 1; a seal casing 25 coupled to the stern tube 5 and surrounding the seal liner 11; and a seal member 27 attached to the seal casing 25 and surrounding the seal liner 11 to seal a gap between the seal casing 25 and the seal liner 11. The seal liner 11 has a plurality of liner partition units coupled to be separable from each other in the peripheral direction around the propeller shaft 1.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a bow-side seal structure provided on the bow side of a stern tube of a ship.

In a ship, a stern tube is provided where the propeller shaft passes through the hull. A bearing that rotatably supports the propeller shaft is provided in the stern tube.

A seal structure is provided on each of the stern and bow sides of the stern tube. The stern side seal structure prevents the lubricating oil supplied to the bearings of the stern tube from leaking outboard and prevents water (seawater) from entering the ship. The bow seal structure prevents the lubricating oil supplied to the bearings of the stern tube from leaking into the inboard engine room, and prevents water (seawater) from entering the engine room.

Each of the aft seal structure and the bow seal structure has a seal liner and a seal casing. The seal liner is attached to the outer circumference of the propeller shaft so as to rotate together with the propeller shaft. A seal casing is coupled to the stern tube to surround the seal liner. The seal casing is provided with a seal member for sealing a gap between the seal casing and the seal liner. Such a seal structure is described in Patent Document 1, for example.

International publication WO2011/004456

As the ship operates, wear occurs in the portion of the seal liner that slides against the seal member. Remove the worn seal liner from the propeller shaft, and attach a new seal liner or a ground seal liner to the propeller shaft.

When replacing the seal liner in this way, it is necessary to remove the seal liner from the propeller shaft. This work can be done as follows for the seal liner of the bow seal structure.

Since the bow-side end of the propeller shaft is connected to the intermediate shaft on the bow side of the bow-side seal structure, the connection between the propeller shaft and the intermediate shaft is released. After that, the intermediate shaft and its attendant mechanism are moved toward the bow side, or the propeller shaft is moved toward the stern side, and then the seal liner is extracted from the bow side end of the propeller shaft. Moving the intermediate shaft and its accessory mechanism or the propeller shaft in this manner is a heavy work load.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to remove a seal liner from a propeller shaft in a bow side seal structure for a stern tube, while the propeller shaft remains as it is (without releasing the connection between the propeller shaft and the intermediate shaft). It's about making it possible.

In order to achieve the above-described object, the bow seal structure according to the present invention is a bow seal structure for a stern tube provided in a ship for allowing a propeller shaft to pass from an engine room inside the hull to the outside of the hull,
a seal liner attached to the outer peripheral surface of the propeller shaft;
a seal casing coupled to the stern tube and surrounding the seal liner;
a seal member attached to the seal casing and surrounding the seal liner so as to block a gap between the seal casing and the seal liner;
The seal liner has a plurality of liner segments separably connected to each other in a circumferential direction around the propeller shaft.

Also, in order to achieve the above objects, the ship according to the invention is:
a stern tube through which the propeller shaft passes from the engine room inside the hull to the outside of the hull;
and the bow-side seal structure that prevents lubricating oil supplied to bearings provided on the inner circumference of the stern tube from leaking into the engine room in the hull.

In the bow seal structure according to the present invention, the seal liner has a plurality of liner splits that are separably connected to each other in the circumferential direction. Therefore, when the seal liner wears, the seal liner is moved toward the bow side so as to be displaced from the seal casing, and the connection between the plurality of liner divisions is released. Can be removed outside. Therefore, the seal liner can be removed from the propeller shaft while the propeller shaft remains as it is.

1 shows the vicinity of a stern tube in a ship provided with a bow-side seal structure according to an embodiment of the present invention; FIG. 2 is a partially enlarged view of FIG. 1 showing a bow seal structure according to an embodiment of the present invention; FIG. 3 is a cross-sectional view IIIA-IIIA of FIG. 2, but showing only the seal liner; In FIG. 3A, the first and second liner halves forming the seal liner are shown separated from each other. FIG. 3 is an IVA-IVA view of FIG. 2, but showing only the seal liner; In FIG. 4A, the first and second liner halves forming the seal liner are shown separated from each other. FIG. 3 is a cross-sectional view taken along line VV of FIG. 2, showing only the clamp ring; FIG. 2 shows a state in which the seal liner and clamp ring are slid toward the bow. An example of modification of the bow side seal structure is shown. FIG. 7 shows the inflatable seal inflated.

Preferred embodiments of the present invention will be described based on the drawings. In addition, the same code|symbol is attached|subjected to the part which is common in each figure, and the overlapping description is abbreviate|omitted.

FIG. 1 shows the vicinity of a stern tube 5 in a ship provided with a bow-side seal structure 10 according to an embodiment of the present invention. As shown in FIG. 1, the ship is provided with a stern tube 5 at a predetermined position on the stern side for passing the propeller shaft 1 from the engine room inside the hull to the outside of the hull. A propeller 3 is coupled to the propeller shaft 1 outside the hull. The propeller shaft 1 is rotationally driven by a main engine (not shown) provided in an engine room inside the hull. Bearings 6 and 7 that rotatably support the propeller shaft 1 are provided on the inner circumference of the stern tube 5 . In addition, in FIG. 1, the right side is the bow side, and the left side is the stern side.

The stern tube 5 is provided with a bow-side seal structure 10 and a stern-side seal structure 20 . The bow-side seal structure 10 prevents the lubricating oil supplied to the bearings 6 and 7 on the bow side of the stern tube 5 from leaking into the engine room in the hull. The stern seal structure 20 prevents water (seawater) from entering the stern tube 5 from outside the hull on the stern side of the stern tube 5, and prevents lubricating oil supplied to the bearings 6 and 7 from entering the stern tube 5. prevent leakage.

FIG. 2 is a partially enlarged view of FIG. 1 showing a bow seal structure 10 according to an embodiment of the present invention. The bow seal structure 10 includes a seal liner 11 , a clamp ring 17 , a seal casing 25 and a seal member 27 .

(Structure of seal liner)
The seal liner 11 is attached to the outer peripheral surface of the propeller shaft 1 as shown in FIG. FIG. 3A is a cross-sectional view taken along IIIA-IIIA of FIG. 2, but shows only the seal liner 11. FIG. 4A is an IVA-IVA view of FIG. 2, but shows only the seal liner 11. FIG. The seal liner 11 has an annular shape surrounding the central axis C (propeller shaft 1 ) when viewed from the direction of the central axis C of the propeller shaft 1 .

The seal liner 11 has first and second liner divisions 11a, 11b. FIG. 3B shows a state in which the first and second liner divisions 11a and 11b constituting the seal liner 11 are separated from each other in FIG. 3A. FIG. 4B shows a state in which the first and second liner divisions 11a and 11b constituting the seal liner 11 are separated from each other in FIG. 4A. The first and second liner divisions 11 a and 11 b are separably connected to each other in the circumferential direction around the central axis C of the propeller shaft 1 to form a seal liner 11 . In the example of FIG. 3A , each of the liner divisions 11 a and 11 b has a length of half the circumference in the circumferential direction around the central axis C of the propeller shaft 1 . In the following, each "circumferential direction" means a circumferential direction around the central axis C, and each "axial direction" means a direction parallel to the central axis C.

As shown in FIGS. 2-4B, each of the first and second liner segments 11a, 11b has a bonding surface 11a1, 11b1. The connecting surface 11a1 of the first liner divided portion 11a and the connecting surface 11b1 of the second liner divided portion 11b contact and are connected to each other in the circumferential direction. Each coupling surface 11a1, 11b1 is a surface facing the circumferential direction. As shown in FIGS. 2 to 4B, bolt hole forming portions 12 are provided at two locations on the bow side (two locations on the top and bottom in FIG. 3A) and two locations on the stern side of the connecting surfaces 11a1 and 11b1 of the liner split portions 11a and 11b. It is formed at two locations (two locations above and below in FIG. 4A). A bolt hole is formed in the bolt hole forming portion 12 . For example, the bolt hole may pass through the bolt hole forming portion 12 .

One circumferential end surface of each bolt hole forming portion 12 forms a part of the corresponding coupling surfaces 11a1 and 11b1. The bolt hole is opened in the one end face in the circumferential direction. A space 13 is provided on the other circumferential end surface side of each bolt hole forming portion 12 in each of the liner dividing portions 11a and 11b. Space 13 is space 13 for arranging bolt 15a or nut 15b. In each of the liner divisions 11a and 11b, the space 13 is formed only in part of the entire circumference in the circumferential direction. As shown in FIG. 3B, the space 13 may be open radially outward. Each of such bolt hole forming portions 12 may be formed integrally with other portions of the corresponding liner division portions 11a and 11b.

The bolt holes of the bolt hole forming portions 12 of the first and second liner dividing portions 11a and 11b are aligned with the bolt hole forming portions 12 aligned in the circumferential direction as shown in FIGS. 3A and 4A. are connected by a bolt 15a and a nut 15b. As a result, the first and second liner divisions 11a and 11b are separably joined together in the circumferential direction to form an annular seal liner 11. As shown in FIG.

In addition, as shown in FIGS. 2 and 3B and the like, a plurality of knock pins 16 may be provided on the coupling surface 11b1 so as to protrude from the coupling surface 11b1. The plurality of knock pins 16 are inserted into the plurality of pin holes formed in the connecting surface 11a when connecting the connecting surfaces 11a1 and 11b1, whereby the connecting surfaces 11a1 and 11b1 are positioned relative to each other.

(Structure of clamp ring)
A clamp ring 17 is provided to fix the seal liner 11 to the propeller shaft 1 . The seal liner 11 is axially slidable with the first and second liner segments 11a and 11b attached to the propeller shaft 1 with the first and second liner segments 11a and 11b coupled together in the circumferential direction. The clamp ring 17 is fixed to the propeller shaft 1 by tightening the propeller shaft 1 . The seal liner 11 is fixed to the propeller shaft 1 by fixing the seal liner 11 to the clamp ring 17 .

FIG. 5 is a cross-sectional view taken along line VV of FIG. 2, showing only the clamp ring 17. As shown in FIG. The clamp ring 17 is clamped and fixed to the outer peripheral surface of the propeller shaft 1 (columnar portion 1a to be described later) by connecting the first and second split ring portions 17a and 17b with bolts 23a (and nuts 23b). be done. The seal liner 11 is axially fixed to the clamp ring 17 by a plurality of bolts 21 on the stern side of the clamp ring 17 .

A plurality of bolt holes penetrate through the clamp ring 17 in the circumferential direction. A bolt 21 axially passes through these bolt holes. The tip end portions of these bolts 21 are respectively screwed into a plurality of female threaded holes provided in the enlarged diameter portion 14 forming the bow end portion of the seal liner 11 . As a result, the clamp ring 17 is sandwiched between the heads of the bolts 21 and the enlarged diameter portion 14 . The seal liner 11 is thereby fixed to the clamp ring 17 .

Each of the ring divisions 17a and 17b has a length of half the circumference in the circumferential direction. Each of the first and second ring divisions 17a and 17b has bolt hole formations 19 at both ends in the circumferential direction. A bolt hole penetrates each bolt hole forming portion 19 . The first and second ring divisions 17a and 17b are inserted into the bolt holes of the bolt hole forming portions 19 with the bolt hole forming portions 19 aligned in the circumferential direction as shown in FIG. It is connected by a bolt 23a and a nut 23b. A space 24 for arranging a bolt 23a and a nut 23b is formed in each of the ring divisions 17a and 17b.

(Structure of Seal Casing and Seal Member)
The seal casing 25 is joined to the stern tube 5 so as to be positioned on the bow side of the stern tube 5 and surrounds the seal liner 11 .

The seal member 27 is attached to the inner circumference of the seal casing 25 and surrounds the seal liner 11 so as to close the gap between the seal casing 25 and the seal liner 11 . The seal member 27 has a ring shape when viewed from the axial direction, and has an inner peripheral surface that contacts the seal liner 11 .

As shown in FIG. 2, the seal casing 25 may have a plurality of axially divided casing divisions 25a, 25b, and 25c. A plurality of casing divisions 25a, 25b, 25c may be axially connected to each other by bolts. The sealing member 27 may be axially sandwiched between the casing divisions 25a, 25b, and 25c that are axially adjacent to each other.

(Configuration of propeller shaft)
The propeller shaft 1 has a cylindrical portion 1a. A cross section of the columnar portion 1a taken along a plane perpendicular to the central axis C is circular with a constant radius regardless of the axial position of the cross section. The cylindrical portion 1a extends continuously in the axial direction from its stern end to its bow end. The stern end of the cylindrical portion 1 a may be, for example, the point where the propeller shaft 1 is coupled to the propeller 3 . The bow-side end of the columnar portion 1a is at a predetermined position on the bow side of the seal liner 11 (joint position with the tapered portion 1b, which will be described later).

The cylindrical portion 1a has a casing-facing portion 1af and a parallel portion 1ap on the bow side of the stern tube 5. As shown in FIG. The casing facing portion 1af is a portion facing the seal casing 25 in the radial direction of the propeller shaft 1 . The parallel portion 1ap extends from the bow-side end of the casing-facing portion 1af toward the bow side to the predetermined position. The bow-side end of the parallel portion 1ap is the bow-side end of the cylindrical portion 1a.

The axial dimension of the parallel portion 1 ap is larger than the axial dimension of the seal liner 11 . In this case, the axial dimension of the parallel portion 1 ap may be greater than the sum of the axial dimension of the seal liner 11 and the axial dimension of the clamp ring 17 .

The propeller shaft 1 has a tapered portion 1b located on the bow side of the cylindrical portion 1a. The bow-side end of the cylindrical portion 1a is joined to the stern-side end of the tapered portion 1b. The tapered portion 1b has a smaller cross section (circular cross section) toward the bow. The columnar portion 1a and the tapered portion 1b may be formed integrally with each other.

A flange 2 is provided at the bow side end of the tapered portion 1b. As shown in FIG. 1, the propeller shaft 1 is coaxially coupled to the intermediate shaft 9 on the bow side via the flange 2 of the tapered portion 1b. The stern end of the intermediate shaft 9 is provided with flanges 2 and 9a. The propeller shaft 1 and the intermediate shaft 9 are connected to each other by connecting the flanges 2 and 9a with bolts and nuts. Rotational driving force from a main engine (not shown) is transmitted to the propeller shaft 1 via an intermediate shaft 9 .

(Removal procedure 1 of seal liner 11)
The seal liner 11 can be removed from the propeller shaft 1 in the order of (A) to (D) below.

(A) The clamp ring 17 is released from the cylindrical portion 1a. That is, the clamp ring 17 weakens the force that clamps the propeller shaft 1 so that the clamp ring 17 can slide on the propeller shaft 1 in the axial direction. In the case of the examples shown in FIGS. 2 and 5, the bolt 23a is slightly turned so as to weaken the fastening force between the ring divisions 17a and 17b.

(B) Next, the clamp ring 17 is slid forward along with the seal liner 11 with respect to the cylindrical portion 1a. As a result, the seal liner 11 is moved to the parallel portion 1 ap on the bow side of the seal casing 25 so as not to radially overlap the seal casing 25 . For example, the seal liner 11 is moved from the position of FIG. 2 to the position of FIG. At this time, since the axial dimension of the parallel portion 1ap is larger than the sum of the axial dimension of the seal liner 11 and the axial dimension of the clamp ring 17, the seal liner 11 and the clamp ring 17 are formed into the cylindrical parallel portion 1ap. It can be stably slid up. Therefore, the seal casing 25, the clamp ring 17, and the propeller shaft 1 are prevented from colliding with each other and being damaged during sliding.

(C) Next, the fixing between the seal liner 11 and the clamp ring 17 is released. For example, the fixation of both by bolts 21 is released.

(D) After that, the clamp ring 17 is separated into a plurality of ring divisions (first and second ring divisions 17a and 17b), and each ring division is removed radially outward from the parallel portion 1ap. , the seal liner 11 is separated into a plurality of liner divisions (first and second liner divisions 11a, 11b), and each liner division is removed radially outwardly from the parallel portion 1ap.

After the seal liner 11 is removed from the propeller shaft 1 (parallel portion 1ap) as described above, the new seal liner 11 or the seal liner 11 that has undergone refining (grinding) is subjected to (A) to (D) described above. It is attached and fixed to the propeller shaft 1 so as to be placed in a position surrounded by the seal casing 25 by reversing the procedure.

(Removal procedure 2 of seal liner 11)
The seal liner 11 can also be removed from the propeller shaft 1 in the order of (a) to (d) below.

(a) As in (A) above, the clamp ring 17 is released from the cylindrical portion 1a.

(b) Next, the fixation between the seal liner 11 and the clamp ring 17 is released in the same manner as in (C) above.

(c) After that, the clamp ring 17 is separated into a plurality of ring divisions (first and second ring divisions 17a and 17b), and each ring division is removed radially outwardly from the parallel portion 1ap.

(d) Next, the seal liner 11 is slid forward with respect to the cylindrical portion 1a. As a result, the seal liner 11 is moved to the parallel portion 1 ap on the bow side of the seal casing 25 so as not to radially overlap the seal casing 25 . At this time, since the axial dimension of the parallel portion 1ap is larger than the axial dimension of the seal liner 11, the seal liner 11 can be stably slid on the cylindrical parallel portion 1ap. Therefore, when sliding, the seal casing 25 and the propeller shaft 1 are prevented from colliding with each other and being damaged.

(e) Thereafter, the seal liner 11 is separated into a plurality of liner divisions (first and second liner divisions 11a and 11b), and each liner division is removed radially outward from the parallel portion 1ap.

After the seal liner 11 is removed from the propeller shaft 1 (parallel portion 1ap) as described above, the new seal liner 11 or the seal liner 11 that has undergone refining (grinding) is removed as described above (a) to (e). It is attached and fixed to the propeller shaft 1 so as to be placed in a position surrounded by the seal casing 25 by reversing the procedure.

(Effects of Embodiment)
In the bow-side seal structure 10 according to the embodiment of the present invention, the seal liner 11 has a plurality of liner divisions (first and second liner divisions 11a and 11b) that are divided from each other in the circumferential direction. The plurality of liner divisions form the seal liner 11 by being connected in the circumferential direction. Therefore, when the seal liner 11 wears, the seal liner 11 is moved to the bow side so as to be displaced from the seal casing 25, and the plurality of liner split portions (the first and second liner split portions 11a and 11b) are connected together. By releasing, each liner split portion can be removed radially outward with respect to the propeller shaft 1 . Therefore, with the propeller shaft 1 left as it is (for example, without releasing the connection between the propeller shaft 1 and the intermediate shaft 9), and with the entire seal casing 25 coupled to the stern tube 5, the seal liner 11 can be removed from the propeller shaft 1 .

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the present invention. For example, any one of Modifications 1 to 3 below may be employed alone, or two or more of Modifications 1 to 3 may be employed in arbitrary combination. In this case, the points not described below are the same as those described above.

(Modification 1)
Although the seal liner 11 is divided in the circumferential direction into the first and second liner divisions 11a and 11b in the above description, the present invention is not limited to this. That is, the seal liner 11 has a plurality of liner divisions that are divided from each other in the circumferential direction. It is sufficient if it is formed. In this case, the liner split portions adjacent to each other in the seed direction may be connected by the same configuration (the bolt hole forming portion 12, the bolt 15a and the nut 15b) as described above. That is, the bolt hole forming portion 12 and the space 13 may be formed at the circumferential end portion of each liner dividing portion.

(Modification 2)
Although the clamp ring 17 is divided in the circumferential direction into the first and second ring divisions 17a and 17b in the above description, the present invention is not limited to this. That is, the clamp ring 17 has a plurality of ring divisions that are divided from each other in the circumferential direction. It is sufficient if it is formed. In this case, the ring divisions adjacent to each other in the seed direction may be connected by the same configuration (the bolt hole forming portion 19, the bolt 23a and the nut 23b) as described above. That is, the bolt hole forming portion 19 and the space 24 may be formed at the circumferential end portion of each ring division portion.

(Modification 3)
FIG. 7 is a diagram corresponding to FIG. 2, but shows the configuration in the case of modification 3. In FIG. In Modification 3, the bow seal structure 10 includes an inflatable seal portion 31 . The inflatable seal portion 31 is attached to the inner circumference of the seal casing 25 (the casing split portion 25 c in the example of FIG. 7) and surrounds the propeller shaft 1 . The inflatable seal portion 31 is an annular member when viewed from the axial direction, and extends continuously in the circumferential direction to make one turn. The inflatable seal portion 31 is positioned aft of the seal liner 11 .

The inflatable seal portion 31 has an internal space 31a that is annular when viewed axially. By supplying pressurized gas (for example, pressurized air) to the internal space 31a, the inflatable seal portion 31 expands so as to close the gap between the seal casing 25 and the seal liner 11, as shown in FIG. That is, the inner peripheral surface of the inflatable seal portion 31 is brought into contact with and pressed against the outer peripheral surface of the propeller shaft 1 .

A gas supply line 33 (for example, a tube) is provided to supply pressurized gas to the internal space 31a. The gas supply passage 33 communicates with the internal space 31a of the inflatable seal portion 31 and extends from the inflatable seal portion 31 to the outside of the seal casing 25 (the casing dividing portion 25c in the example of FIG. 7).

In this modification, in order to remove the seal liner 11 from the propeller shaft 1, before the seal liner 11 is moved to the parallel portion 1ap on the bow side of the seal casing 25 (for example, the above (B) in the removal procedure 1 described above). or before (d) above in removal procedure 2 above), the inflatable seal 31 is inflated. As a result, the gap between the seal casing 25 and the outer peripheral surface of the propeller shaft 1 is sealed by the expandable seal portion 31 . Therefore, even if the seal liner 11 is removed from the propeller shaft 1, the lubricating oil is prevented from leaking from inside the stern tube 5 into the engine room.

1 propeller shaft 1a cylindrical portion 1af casing facing portion 1ap parallel portion 1b tapered portion 2 flange 3 propeller 5 stern tube 6, 7 bearing 9 intermediate shaft 9a flange 10 bow side seal structure 20 stern side seal structure 11 seal liner 11a, 11b first and second liner divisions 11a1, 11b1 joining surface 12 bolt hole forming portion 13 space 14 enlarged diameter portion 15a bolt 15b nut 16 knock pin, 17 clamp ring, 17a, 17b first and second ring divisions, 19 bolt hole forming portion, 21 bolt, 23a bolt, 23b nut, 24 space, 25 seal casing, 25a, 25b, 25c casing division, 27 seal member 31 inflatable seal portion 31a internal space 33 gas supply passage C central axis

Claims (6)

A bow-side seal structure for a stern tube provided in a ship and passing a propeller shaft from an engine room inside the hull to the outside of the hull,
a seal liner attached to the outer peripheral surface of the propeller shaft;
a seal casing coupled to the stern tube and surrounding the seal liner;
a seal member attached to the seal casing and surrounding the seal liner so as to block a gap between the seal casing and the seal liner;
The bow-side seal structure, wherein the seal liner has a plurality of liner divisions separably connected to each other in a circumferential direction around the propeller shaft. comprising the propeller shaft;
The propeller shaft has a cylindrical portion,
The cylindrical portion includes a casing-facing portion facing the seal casing in the radial direction of the propeller shaft and a parallel portion extending from the bow-side end of the casing-facing portion toward the bow,
2. The bow-side seal structure according to claim 1, wherein the axial dimension of the parallel portion is greater than the axial dimension of the seal liner, where the length of the propeller shaft in the axial direction is the axial dimension. Having a clamp ring fixed to the outer peripheral surface of the cylindrical portion on the bow side of the seal liner,
the seal liner attached to the outer peripheral surface of the cylindrical portion is fixed to the clamp ring fixed to the cylindrical portion;
3. A bow seal arrangement according to claim 2, wherein the axial dimension of the parallel portion is greater than the sum of the axial dimension of the seal liner and the axial dimension of the clamp ring. the propeller shaft has a tapered portion located on the bow side of the cylindrical portion;
the bow end of the parallel portion is coupled to the stern end of the tapered portion;
3. The bow-side seal structure according to claim 2, wherein the tapered portion has a cross-sectional size that decreases toward the bow. an inflatable seal attached to the seal casing and surrounding the propeller shaft;
The inflatable seal portion has an internal space, and when pressurized gas is supplied to the internal space, the inflatable seal portion expands so as to close the gap between the seal casing and the seal liner. 5. The bow side seal structure according to any one of Items 1 to 4. a stern tube through which the propeller shaft passes from the engine room inside the hull to the outside of the hull;
and a bow-side seal structure according to any one of claims 1 to 5, which prevents lubricating oil supplied to bearings provided on the inner periphery of the stern tube from leaking into the engine room in the hull. vessel.

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