JP2005041348A - Shaft seal device and shaft seal method for propeller shaft for ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain positive sealing capability for a long period. <P>SOLUTION: A propeller shaft 2 is surrounded by a casing 5 fixed at a stern tube 3, an air seal chamber 15 is formed in the casing 5, a non-rotating type seal 7 and a rotating type seal 6 for water seal are provided between the air seal chamber 15 and the outboard side. A non-rotating type seal 8 for oil seal is provided between the air seal chamber 15 and a lubrication oil chamber 16 in the stern tube 3, a rotating type seal 9 is provided between the non-rotating type seal and the lubrication oil chamber 16, a seal air supply means A for supplying air for seal to the water seal side is connected with the air seal chamber 15, and a work control means B for switching between a seal working condition and a waiting condition is connected with the rotating type seal 9 on the lubrication chamber 16 side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a shaft sealing device and a shaft sealing method for a marine propulsion shaft.

  In a ship, a stern tube that rotatably holds a propulsion shaft (screw shaft) is provided with a shaft seal device on the outer side of the stern tube. By this shaft seal device, lubricating oil in the stern tube is transmitted along the propulsion shaft. While preventing leakage to the outside of the ship, inundation into the ship is prevented. There exists what is called an air seal system in this kind of shaft seal device. In this air seal system, a plurality of seal rings are skewered with respect to the propulsion shaft, and an air seal chamber that is independent in the axial direction is formed between two seal rings adjacent to each other. Air that is higher in pressure than the outside water pressure (hereinafter referred to as “draft pressure”) is supplied, thereby maintaining the state in which air blows out from the air seal chamber along the propulsion shaft 2 to the outside of the ship. Or fresh water) (see Patent Document 1).

  By the way, the seal ring employed in this air seal type shaft seal device makes the inward lip portion slidable while generating a tightening force on the outer surface of the propulsion shaft, and its outer peripheral portion is fixed in the casing. Usually, it is a “non-rotating seal”. In this non-rotating type seal, even if the propulsion shaft moves, the sealing function is not adversely affected. However, the non-rotating seal has one aspect that the followability is poor with respect to the movement of the propulsion shaft in the radial direction. This non-rotating seal is therefore beneficial for oil-lubricated stern tubes where the bearing portion is hardly worn. Such oil-lubricated stern tubes are often equipped with large ships that have a high draft and therefore a high draft pressure (bearing load) and require high load resistance. Was often used on large ships. For this reason, the non-rotating seal is sometimes called an “oil seal” or the like.

  On the other hand, a seal ring called a “water seal” is known, which is fixed to the propeller shaft so as to be integrally rotatable, and against an annular seal surface provided around the propeller shaft in the casing. This is a “rotary seal” in which the lip portion is slidable while generating an axial pressing force. With this rotary seal, it is possible to follow even if the propulsion shaft moves in the radial direction. However, since the shape of the lip portion is a thin sheet, the lip portion is likely to be worn under a large pressure. Therefore, such a rotary seal has a shallow draft and does not act on a large draft pressure, such as a small ship. It was used in water-lubricated bearings (propulsion shaft diameter is small).

Some shaft seals use a non-rotating seal (oil seal) as the oil-side seal near the stern tube, and a rotating seal (water seal) as the water-side seal near the stern tube. Known (for example, see Patent Documents 2 to 4).
Japanese Patent No. 3155505 Japanese Patent No. 2909948 Japanese Patent No. 3117332 JP 2002-340199 A

Oil-lubricated bearings tend to use non-polluting oils such as biodegradable oils in recent years because the leakage of lubricating oil in the stern tube to the outside of the ship leads to marine pollution. Therefore, it is inferior in lubricity, and therefore there is a concern about the occurrence of wear in the resin bearing. This is an important problem especially for large ships where the draft is deep and therefore the draft pressure and the hydraulic pressure in the stern tube are high. That is, if radial movement of the propulsion shaft occurs due to wear of the bearing, the non-rotating seal alone has a limit in maintaining the sealing performance.
By the way, in order to cope with this, a shaft seal device in which a non-rotating seal is used as an oil-side seal near the stern tube and a rotating seal is used as a water-side seal near the stern tube (Patent Documents 2 to 5). Suppose that the document 4) was adopted by a large ship. However, in large ships, as the draft pressure is high, the lip part of the rotary seal wears out quickly and its life is significantly shortened. As a result, radial movement occurs in the rotation of the propulsion shaft. Sometimes the sealing performance cannot be maintained.

In view of the above circumstances, an object of the present invention is to provide a shaft sealing device and a shaft sealing method for a marine propulsion shaft that can maintain good sealing performance.
According to the present invention, a non-rotating seal and a rotating seal are provided on the outside of the air seal chamber and the lubricating oil chamber, respectively, and by using each rotating seal as a spare, reliable sealing performance can be maintained over a long period of time. An object of the present invention is to provide a shaft sealing device and a shaft sealing method for a marine propulsion shaft.

Specific means for solving the problems in the present invention are as follows.
First, the propulsion shaft 2 is surrounded by a casing 5 fixed to the stern tube 3, an air seal chamber 15 is formed in the casing 5, and a non-rotating seal 7 for water sealing is provided between the air seal chamber 15 and the outside of the ship. Between the air seal chamber 15 and the lubricating oil chamber 16 in the stern tube 3, and a non-rotating seal 8 for oil seal is provided between the non-rotating seal and the lubricating oil chamber 16. A rotary seal 9 is provided in between,
A seal air supply means A for supplying sealing air to the water seal side is connected to the air seal chamber 15, and an action control means B for switching between a sealing action state and a standby state is connected to the rotary seal 9 on the lubricating oil chamber 16 side. Is.

  As a result, a hydraulic pressure for reducing the differential pressure with respect to the hydraulic pressure in the lubricating oil chamber 16 is added to the rotary seal 9 on the lubricating oil chamber 16 side via the action control means B to enter a standby state. The mold seal 6 is in a quasi-seal action state by supplying sealing air, and the two rotary seals 6 and 9 on both sides of the air seal chamber 15 are in a standby state as spare parts. The shaft of the propulsion shaft 2 is sealed with the two non-rotating seals 7 and 8, and the shaft of the propulsion shaft 2 is sealed using the two rotating seals 6 and 9 after the non-rotating seals 7 and 8 are worn. be able to.

Secondly, the rotary seal 6 on the outer side of the ship is located on the outer side of the ship or on the air seal chamber 15 side with respect to the non-rotary seal 7 for water seal, and the seal is applied to the rotary seal 6 from the air seal chamber 15 side. That is, the action control means C is connected to reinforce the sealing action by applying a water pressure larger than the air pressure.
As a result, the rotary seal 6 on the outside of the ship is always supplied with sealing air and is in a semi-sealing state, and after the non-rotating seal 7 for water sealing is worn, the propulsion shaft is substituted for the non-rotating seal 7. If the shaft seal is not sufficient, the action control means C applies a large water pressure to the rotary seal 6 to strengthen the sealing action, thereby ensuring a more reliable shaft seal. Can do.

Thirdly, the action control means B of the rotary seal 9 on the lubricating oil chamber 16 side performs lubrication to add a hydraulic pressure for reducing the differential pressure with respect to the hydraulic pressure of the lubricating oil chamber 16 applied to the rotary seal 9. It is an oil supply stop means.
As a result, the rotary seal 9 always receives the hydraulic pressure of the lubricating oil chamber 16, but when a differential pressure is reduced by applying a hydraulic pressure that opposes the hydraulic pressure, the quasi-seal action is achieved. The oil pressure in the oil chamber 16 results in a sealing action state, and the sealing action state and the standby state can be switched easily and easily.

Fourth, the drain means 50 is connected to the air seal chamber 15.
As a result, when water, oil or the like leaks from the water seal and oil seal seals to the air seal chamber 15, they can be processed in the ship without being discarded into the sea.
Fifth, as a shaft sealing method, the propulsion shaft 2 is surrounded by a casing 5 fixed to the stern tube 3, an air seal chamber 15 is formed in the casing 5, and a water seal is formed between the air seal chamber 15 and the outside of the ship. A non-rotating seal 7 and a rotating seal 6 are provided, a non-rotating seal 8 for oil seal is provided between the air seal chamber 15 and the lubricating oil chamber 16 in the stern tube 3, and the non-rotating seal and lubrication are provided. A rotary seal 9 is provided between the oil chamber 16 and
While supplying sealing air from the air seal chamber 15 to the non-rotating seal 7 and the rotating seal 6 for water sealing,
After the non-rotating seal 8 has been used (bearing), a hydraulic pressure for reducing the differential pressure with respect to the hydraulic pressure in the lubricating oil chamber 16 is applied to the rotating seal 9 on the lubricating oil chamber 16 side to set the standby state. When the non-rotating seal 8 becomes difficult to seal due to wear of the rotating seal 9), the additional hydraulic pressure of the rotating seal 9 is canceled and the standby state is switched to the sealing action state.
After the non-rotating seal 7 is used (when it becomes difficult to seal with the non-rotating seal 7 due to bearing wear), the sealing state is strengthened by applying a water pressure greater than the pressure of the sealing air to the rotating seal 6. It is to be.

  Thus, immediately after service or immediately after repair, the propulsion shaft 2 is sealed with the two non-rotating seals 7 and 8 on both sides of the air seal chamber 15, and the seal by the non-rotating seals 7 and 8 is caused by the wear of the bearings. After it becomes difficult, the propulsion shaft 2 is sealed using the two rotary seals 6 and 9 that have been in a standby state, and it is possible to prevent the intrusion of seawater and the leakage of oil overboard for a long period of time. The sealing action of the two rotary seals 6, 9 at the time can also be ensured.

  According to the present invention, the shaft seal of the marine propulsion shaft can be reliably maintained over a long period of time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a first embodiment of a shaft seal device 1 for a marine propulsion shaft according to the present invention. The shaft seal device 1 is provided at the outer end portion of the stern tube 3 that rotatably holds the propulsion shaft 2 and has a casing 5 surrounding the propulsion shaft 2. Inside, a plurality of seal rings 6 to 9 are provided in a state of being skewered with respect to the propulsion shaft 2. It should be noted that a sleeve-shaped liner 12 is extrapolated on the propulsion shaft 2 so as to rotate integrally therewith, and the propulsion shaft including the liner 12 is shown. However, the extrapolation of the liner 12 is not limited.

In the first embodiment, there are four seal rings 6 to 9, and among these, the seal rings 6 and 9 on both sides in the axial direction are “rotary seals (shaft fixing seals)”, and two are sandwiched between them. The seal rings 7 and 8 are “non-rotating type seals (hole fixing seals)”. The two seal rings 7 and 8 which are the non-rotating seals form an air seal chamber 15 which is independent in the axial direction around the propulsion shaft 2 between them.
A seal ring 9, which is a rotary seal arranged on the stern tube 3 side of the air seal chamber 15, partitions between the lubricating oil chamber 16 and the air seal chamber 15 formed in the stern tube 3. An intermediate lubricating oil chamber 17 is formed near the chamber 15. At this time, a stern tube side seal storage chamber 19 is formed on the stern tube 3 side of the intermediate lubricant chamber 17 so as to surround the propulsion shaft 2 while communicating with the lubricant chamber 16 in the stern tube 3. The seal ring 9 is accommodated in the stern tube side seal storage chamber 19.

Further, the seal ring 6, which is a rotary seal disposed on the outer side of the ship relative to the air seal chamber 15, forms an intermediate seal chamber 18 near the air seal chamber 15 by partitioning the outside of the ship and the air seal chamber 15. ing. At this time, an outboard seal storage chamber 20 is formed outside the intermediate seal chamber 18 so as to surround the propulsion shaft 2 while communicating with the outside of the ship, and the seal is sealed in the outboard seal storage chamber 20. The ring 6 can be accommodated.
Accordingly, a non-rotating seal 7 and a rotating seal 6 for sealing the seawater are provided between the air seal chamber 15 and the outside of the boat, and the lubricant chamber 16 in the air seal chamber 15 and the stern tube 3 is provided. A non-rotating seal 8 and a rotating seal 9 for sealing oil are provided between them.

Sealed air supply means A having an air supply line 22, action control means B having a lubricating oil supply line 23, and action control means C having a water supply line 24 are connected to the casing 5.
The sealing air supply means A supplies air to the air seal chamber 15 in order to supply sealing air to the water seal side. The air supply line 22 has a pressure higher than the draft pressure from the air pressure control unit 25. Sealing air is always supplied. The sealing air applies air pressure not only to the water seal side but also to the oil seal side.

The action control means B supplies lubricating oil to the intermediate lubricating oil chamber 17 to switch the rotating seal 9 on the lubricating oil chamber 16 side between the sealing action state and the standby state. Is supplied with lubricating oil from a hydraulic unit (not shown) for supplying lubricating oil to the lubricating oil chamber 16 in the stern tube 3.
In this hydraulic unit, the supply pressure that is necessarily higher than the internal pressure of the air seal chamber 15 by adding the air pressure generated by the air pressure control unit 25 to the head pressure generated by installing the oil tank at a predetermined height. On the lubricating oil.

Therefore, by supplying this lubricating oil to the intermediate lubricating oil chamber 17, it is possible to set the intermediate lubricating oil chamber 17 and the stern tube 3 (lubricating oil chamber 16) to the same pressure (small differential pressure). Moreover, these internal pressures can be made higher than the internal pressure of the air seal chamber 15. The lubricating oil supply line 23 is provided with a control valve 26, which can supply or stop the lubricating oil. The action control means B of the rotary seal 9 on the lubricating oil chamber 16 side is a lubricating oil supply stop means for adding a hydraulic pressure for reducing the differential pressure with respect to the hydraulic pressure of the lubricating oil chamber 16 applied to the rotary seal 9. That is, the action control means B of the rotary seal 9 on the lubricating oil chamber 16 side is a lubrication that adds a hydraulic pressure for reducing the differential pressure with respect to the hydraulic pressure of the lubricating oil chamber 16 applied to the rotary seal 9. Oil supply stopping means.

The action control means C applies seawater or fresh water to the outboard seal storage chamber 20 in order to apply a water pressure larger than the pressure of the sealing air applied from the air seal chamber 15 side to the rotary seal 6 to enhance the sealing action. The water supply line 24 is provided with an opening / closing valve 27, and opening the opening / closing valve 27 allows the outboard seal storage chamber 20 to be equal to or higher than the internal pressure of the air seal chamber 15. it can.
The seal rings 7 and 8 which are non-rotating type seals are of the same shape and are used in reverse directions, and are inwardly slidably in contact with the outer surface of the propulsion shaft 2 as shown in FIG. A lip portion 30, a cushion portion 31 projecting radially outward from the lip portion 30, and a mounting rib 32 provided on the ring outer periphery side of the cushion portion 31. And fixed to the inner peripheral surface of the casing 5. The cushion portion 31 is bent into a “<” shape in cross section, has flexibility within a predetermined range in the radial direction, and receives pressure on the back side of the lip portion 30 by this bent shape. The recess 33 can be formed. A ring spring 34 is provided on the back of the lip portion 30 so as to surround the entire circumference. As a result, a predetermined tightening force is generated in the lip portion 30 against the outer surface of the propulsion shaft 2.

These seal rings 7 and 8 are used such that each pressure receiving recess 33 faces the outside with the air seal chamber 15 as a center. That is, in the seal ring 7 that divides the air seal chamber 15 and the intermediate seal chamber 18, the pressure receiving recess 33 is directed toward the intermediate seal chamber 18, and in the seal ring 8 that divides the air seal chamber 15 and the intermediate lubricating oil chamber 17. The pressure receiving recess 33 is directed to the intermediate lubricating oil chamber 17 side.
As for the seal rings 6 and 9 which are rotary seals, the same shape of the seal rings 6 and 9 are used in the reverse direction, and as shown in FIG. A shoulder portion 38 having a hook-shaped cross-sectional shape projecting on the outer peripheral side of the mounting seat 37, and a trumpet shape around the propulsion shaft 2 in the hook-shaped inner side of the shoulder portion 38 gradually. The lip portion 39 has an enlarged diameter, and is fixed so as to be integrally rotatable by pressing the mounting seat 37 around the propulsion shaft 2. Further, a ring spring 40 is provided on the back portion of the mounting portion 37 so as to surround the entire circumference thereof, whereby a predetermined urging force is applied to the mounting on the propulsion shaft 2. The surface of the lip portion 39 facing the inside of the trumpet-shaped mouth is brought into contact with an annular seal surface 42 provided around the propulsion shaft 2 inside the casing 5 to form a slidable contact surface 39a. At this time, the portion opposite to the sliding contact surface 39 a is the pressure receiving recess 43.

These seal rings 6 and 9 are used such that each pressure receiving recess 43 faces the outside with the air seal chamber 15 as a center. That is, in the seal ring 6 that partitions the intermediate seal chamber 18 and the outside of the ship, the pressure receiving recess 43 is directed to the outboard seal storage chamber 20, and the seal ring that partitions the intermediate lubricant chamber 17 and the lubricant chamber 16. 9, the pressure receiving recess 43 is directed to the stern tube-side seal housing portion 19.
A wall surface 45 is provided inside the casing 5 so as to face the annular seal surface 42 with a predetermined interval. The stern tube-side seal storage chamber 19 and the outboard seal storage chamber are provided between the both surfaces 42, 45. 20 is formed. Between the stern tube side seal storage chamber 19 and the seal ring 6 housed here, and between the outboard seal storage chamber 20 and the seal ring 6 housed here, the distance between both surfaces 42 and 45 is L0, When the thickness dimension including the shoulder portion 38 in the seal ring 6 is L1, and the thickness dimension including the lip portion 39 is L2, a dimensional relationship of L1 <L0 <L2 is obtained. That is, from the relationship of L1 <L0, a clearance for water or air is secured between the inner surface of the outboard seal storage chamber 20 and the outer surface of the seal ring 6, and from the relationship of L0 <L2. A predetermined axial pressing force against the annular seal surface 42 is generated at the lip 39 of the seal ring 6. The wall surface 45 has a hole in the axial direction so as not to hinder the flow of oil, water and air.

By reducing (including zero) the differential pressure between the pressure applied to both sides of the lip portion 39 (water pressure and air pressure or hydraulic pressure and hydraulic pressure, which are front pressure and back pressure), the lip portion 39 is a natural body and forms an annular seal surface 42. Abutment can seal water and oil, and if the pressure in the abutment direction becomes high, the sealing action becomes large and strong, and the pressure in the abutment direction is applied or the applied pressure is eliminated. Thus, the rotary seals 6 and 9 can be switched between the sealing action state and the standby state.
The rotary type seals 6 and 9 are in a non-sealing state in which the standby state is not used for positively sealing the shaft, and are in a semi-sealing state because they contact with a natural body even in an unloaded state.

The propulsion shaft 2 is provided with a drain means 50 for removing water or lubricating oil collected in the air seal chamber 15 from the water seal side, and leaked from the seawater entering from the water seal side and from the oil seal side. The oil can be recovered on board without being abandoned to the sea.
In the shaft seal device 1 having such a configuration, initially, air having a pressure higher than the draft pressure is supplied from the air pressure control unit 25 to the air seal chamber 15 through the air supply line 22, and the lubricating oil chamber in the stern tube 3 is supplied. 16 and the stern tube side seal storage chamber 19 are supplied with lubricating oil from the hydraulic unit at a supply pressure higher than the air supply pressure to the air seal chamber 15, and the intermediate seal chamber 18 is filled with grease. The seal storage chamber 20 is in a state where seawater or fresh water outside the ship has entered.

  When the ship is just after launching or just after receiving a bearing replacement by repair at the dock, the propeller shaft 2 hardly moves in the radial direction when the bearing is not worn. Therefore, the control valve 26 of the lubricating oil supply line 23 is opened, and lubricating oil is supplied to the intermediate lubricating oil chamber 17. As described above, since the lubricating oil is supplied to the lubricating oil supply line 23 in the same manner from the hydraulic unit that supplies the lubricating oil to the lubricating oil chamber 16 and the like in the stern tube 3, The internal pressure and the internal pressure of the stern tube 3 are equivalent, and the differential pressure is zero. Therefore, the seal ring 9, which is a rotary seal on the stern tube 3 side, receives the front pressure received from the intermediate lubricating oil chamber 17 side and the back pressure received from the lubricating oil chamber 16 side via the pressure receiving recess 43 at the lip portion 39. Balance and no load.

  The on-off valve 27 of the water supply line 24 is closed (disconnected). The air seal chamber 15 is higher than the draft pressure, the outboard seal storage chamber 20 is balanced with the draft pressure, and the intermediate seal chamber 18 is balanced with an internal pressure between the internal pressure of the air seal chamber 15 and the draft pressure. From the air seal chamber 15, a small amount of air is blown out of the ship through the intermediate seal chamber 18 while pushing a part of the lip portion 30 of the seal ring 7 and a part of the lip portion 39 of the seal ring 6. Maintained. However, since the tightening force to the outer surface of the propulsion shaft 2 of the seal ring 7 itself acts on the lip portion 30 of the seal ring 7, air, water, and oil from the intermediate seal chamber 18 toward the air seal chamber 15. Etc., backflow is prevented.

For this reason, at this stage, the seal ring 7 which is a non-rotating type seal arranged on the outside of the ship in the air seal chamber 15 and the seal ring 8 which is a non-rotating type seal arranged near the stern tube 3 are shafts. The seal ring 6 is responsible for the sealing function of the sealing device 1, and the seal ring 6, which is a rotary seal that partitions the intermediate seal chamber 18 from the outside of the ship, and the rotation that partitions the intermediate lubricant chamber 17 and the stern tube 3. About the seal ring 9 which is a type | mold seal | sticker, it waits in a substantially no-load state.
Here, it is assumed that radial movement occurs in the propulsion shaft 2 due to wear of the bearing. For this reason, it is assumed that the sealing performance of the seal ring 8 which is a non-rotating seal disposed on the stern tube 3 side in the air seal chamber 15 is not secured. That is, the lubricating oil in the intermediate lubricating oil chamber 17 leaks to the air seal chamber 15 (the seal ring 8 has been used).

  At this time, the control valve 26 of the lubricating oil supply line 23 is closed to stop the supply of lubricating oil to the intermediate lubricating oil chamber 17. Then, the internal pressure of the intermediate lubricating oil chamber 17 is only the pressure of the sealing air from the air seal chamber 15 leaking from the worn seal ring 8, and becomes lower than the internal pressure of the lubricating oil chamber 16, so that it is a rotary seal. In the seal ring 9, the back pressure from the stern tube 3 side against the lip portion 39 exceeds the front pressure from the intermediate lubricating oil chamber 17 side. As a result, the seal ring 9 is operated at this point. As a result, the seal ring 8 that is the non-rotating seal on the stern tube 3 side can compensate for the fact that the sealing performance is no longer ensured.

  On the other hand, it is assumed that the sealing performance of the seal ring 7 which is a non-rotating seal disposed outside the ship is not ensured in the air seal chamber 15 due to the radial movement of the propulsion shaft 2 described above (the seal ring 7 is used). ). Since the air blown out from the air seal chamber 15 to the intermediate seal chamber 18 is slightly higher than the draft pressure, the seal ring 6 seals the shaft in a substantially no-load state while leaking air. However, if this shaft seal function does not function sufficiently, water equal to or higher than the internal pressure of the air seal chamber 15 from the water supply line 24 toward the outboard seal storage chamber 20 on the outer side of the seal ring 6 can be obtained. Supply.

  As a result, the back pressure, which has been dominated only by the draft pressure, is increased, and the seal ring 6 is in a state of being balanced against the front pressure received from the intermediate seal chamber 18 side. At this time, since the axial pressing force against the annular seal surface 42 of the seal ring 6 itself is acting on the lip portion 39 of the seal ring 6, the water in the outboard seal storage chamber 20 is transferred to the intermediate seal chamber 18. Intrusion is prevented, and a sealing action is achieved. As a result, the seal ring 6 is activated, and the seal ring 7 which is a non-rotating seal on the outside of the ship can compensate for the fact that the sealing performance is not ensured. However, even in this sealed state, a part of the lip portion 39 is pushed back in the seal ring 6 and a small amount of air is allowed to blow out from the intermediate seal chamber 18 to the outside of the ship.

  Thus, at the stage where the propulsion shaft 2 starts to move in the radial direction, the seal ring 6 that is a rotary seal that partitions the intermediate seal chamber 18 and the outside of the ship, and the intermediate lubricant chamber 17 and the stern tube 3 are partitioned. Sealing performance is ensured by using a seal ring 9 which is a rotary seal. Even if these seal rings 9 and 6 which are rotary seals are operated, the differential pressure acting on the seal ring 9 on the stern tube 3 side should be kept as small as 0.3 bar as long as the air supply to the air seal chamber 15 is continued. In addition, the differential pressure acting on the seal ring 6 on the outside of the ship can be kept at zero, so that the seal rings 9 and 6 are not worn out immediately after the operation and the sealing performance is not lost.

  FIG. 4 shows a second embodiment of the shaft seal device 1 for a marine propulsion shaft according to the present invention. In the shaft seal device 1 of the second embodiment, the seal ring on the oil seal side is the seal ring 8 with the non-rotating seal on the air seal chamber 15 side and the rotary type on the lubricating oil chamber 16 side, as in the first embodiment. In contrast to the seal ring 9 of the seal, the seal ring on the outboard water seal side is opposite to that of the first embodiment, the air seal chamber 15 side is the seal ring 6 of the rotary seal, and the outer side of the ship is the non-rotation type. The seal ring 7 is a seal, and an intermediate seal chamber 72 is formed between the seal rings 6 and 7.

  In order to accommodate the seal ring 6 disposed on the outer side of the ship from the air seal chamber 15, a seal storage chamber 20 is formed in the casing 5, and this seal storage chamber 20 communicates with the intermediate seal chamber 72 through the communication hole 75. It has become. And the water supply line 24 which supplies water, such as seawater or fresh water, with respect to this seal | sticker storage chamber 20, is provided, and this water supply line 24 is provided with the on-off valve 27, and the action control means C is comprised by these. . By opening the on-off valve 27, the seal storage chamber 20 and the intermediate seal chamber 72 can be made equal to or higher than the internal pressure of the air seal chamber 15.

  In the shaft seal device 1 according to the second embodiment, when the bearing is not worn and the radial movement of the propulsion shaft 2 hardly occurs, the water supply line 24 is closed (disconnected). In the seal ring 6, which is a rotary seal disposed on the outside of the ship in the air seal chamber 15, a part of the lip portion 39 is pushed back by receiving the internal pressure of the air seal chamber 15, so that the air seal chamber 15 moves to the intermediate seal chamber 72. In order to allow air to blow out, the internal pressure of the intermediate seal chamber 72 is balanced by an internal pressure substantially equal to the internal pressure of the air seal chamber 15 and is in a standby state. However, since an axial pressing force against the annular seal surface 42 of the seal ring 6 itself acts on the lip portion 39 of the seal ring 6, air directed from the intermediate seal chamber 72 to the air seal chamber 15, Backflow of water, oil, etc. is prevented. Needless to say, the internal pressure of the air seal chamber 15 is set higher than the draft pressure.

On the other hand, in the seal ring 7 which is a non-rotating seal that divides the intermediate seal chamber 72 and the outside of the ship, a part of the lip portion 30 is received in response to the internal pressure of the intermediate seal chamber 72 being higher than the draft pressure outside the ship. A small amount of air is allowed to blow out from the intermediate seal chamber 7 to the outside of the ship. However, since the fastening force to the outer surface of the propulsion shaft 2 included in the seal ring 7 itself is acting on the lip portion 30, the inundation from the outside of the ship toward the intermediate seal chamber 72 is prevented.
As a result, in this stage, the shaft seal device 1 waits in a substantially unloaded state with the seal ring 6, which is a rotary seal disposed on the outside of the ship in the air seal chamber 15, and from this, the non-rotation is disposed on the outside of the ship. The seal ring 7 which is a mold seal maintains the sealing action state.

Here, it is assumed that radial movement occurs in the propulsion shaft 2 due to wear of the bearing. Then, seawater enters the intermediate seal chamber 72 from the outside of the ship beyond the seal ring 7 which is a non-rotating seal on the outer side of the ship, but the seal air from the air seal chamber 15 is received in the seal ring 6 which is a rotary seal. In addition to passing, it seals the ingress of seawater with its own sealing force. When the sealing force is insufficient, the on-off valve 27 of the water supply line 24 is opened and pressurized water is supplied through the water supply line 24, thereby ensuring the operation of the seal ring 6.
Thus, at the stage where the propulsion shaft 2 starts to move in the radial direction, the sealing performance is secured by using the seal ring 6 which is a rotary seal disposed on the outer side of the air seal chamber 15.

In the present invention, the shape of each member and the positional relationship between the front, rear, left, and right in the embodiment are best configured as shown in FIGS. However, it is not limited to the said embodiment, A member, a structure can be variously deformed, and a combination can also be changed.
For example, a non-rotating seal 7 and a rotating seal 6 are arranged for a water seal, and a non-rotating seal 8 and a rotating seal 9 are arranged for an oil seal, respectively. Three or more seal rings may be arranged, and each seal ring 6, 7, 8, 9 may be arranged in twin.

It is the principal part expanded sectional view which showed 1st Embodiment of the shaft-seal apparatus which concerns on this invention. It is an expanded sectional view showing a seal ring which is a non-rotating type seal. It is an expanded sectional view showing a seal ring which is a rotary seal. It is a principal part expanded sectional view which showed 2nd Embodiment of the shaft-seal apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft seal device 2 Propulsion shaft 3 Stern tube 5 Casing 6 Seal ring (rotary seal)
7 Seal ring (non-rotating seal)
8 Seal ring (non-rotating seal)
9 Seal ring (Rotary seal)
DESCRIPTION OF SYMBOLS 15 Air seal chamber 17 Intermediate lubricating oil chamber 18 Intermediate seal chamber 50 Drain means A Seal air supply means B Action control means C Action control means

Claims (5)

The propulsion shaft (2) is surrounded by a casing (5) fixed to the stern tube (3), an air seal chamber (15) is formed in the casing (5), and water is placed between the air seal chamber (15) and the outside of the ship. A non-rotating seal (7) and a rotating seal (6) are provided for sealing, and a non-rotating oil seal is provided between the air seal chamber (15) and the lubricating oil chamber (16) in the stern tube (3). A mold seal (8) is provided, and a rotary mold seal (9) is provided between the non-rotating mold seal and the lubricating oil chamber (16).
Seal air supply means (A) for supplying sealing air to the water seal side is connected to the air seal chamber (15), and the rotary seal (9) on the lubricating oil chamber (16) side has a sealing action state and a standby state. A shaft seal device for a marine propulsion shaft, characterized in that an action control means (B) for switching between the two is connected.   The rotary seal (6) on the outer side of the ship is located on the outer side of the ship or on the air seal chamber (15) side with respect to the non-rotary seal (7) for water seal, and the air seal chamber (15) is connected to the rotary seal (6). 2. A shaft seal for a marine propulsion shaft according to claim 1, further comprising an action control means (C) for applying a water pressure larger than the pressure of the sealing air applied from the side to strengthen the sealing action. apparatus.   The action control means (B) of the rotary seal (9) on the lubricating oil chamber (16) side reduces the differential pressure with respect to the hydraulic pressure of the lubricating oil chamber (16) applied to the rotary seal (9). 3. A shaft seal device for a marine propulsion shaft according to claim 1 or 2, characterized in that the oil supply stop means applies a hydraulic pressure of.   The shaft sealing device for a marine propulsion shaft according to any one of claims 1 to 3, wherein a drain means (50) is connected to the air seal chamber (15). The propulsion shaft (2) is surrounded by a casing (5) fixed to the stern tube (3), an air seal chamber (15) is formed in the casing (5), and water is placed between the air seal chamber (15) and the outside of the ship. A non-rotating seal (7) and a rotating seal (6) are provided for sealing, and a non-rotating oil seal is provided between the air seal chamber (15) and the lubricating oil chamber (16) in the stern tube (3). A mold seal (8) is provided, and a rotary mold seal (9) is provided between the non-rotating mold seal and the lubricating oil chamber (16).
While supplying sealing air from the air seal chamber (15) to the non-rotating seal (7) and the rotating seal (6) for water sealing,
A hydraulic pressure for reducing a differential pressure with respect to the hydraulic pressure in the lubricating oil chamber (16) is added to the rotating seal (9) on the lubricating oil chamber (16) side to set a standby state. 8) After the use of the rotary seal (9) to release the additional hydraulic pressure and switch from the standby state to the sealing action state,
A shaft of a marine propulsion shaft characterized in that after the non-rotating seal (7) on the outside of the ship is used, the sealing state is strengthened by applying a water pressure larger than the pressure of the sealing air to the rotating seal (6). Sealing method.

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