Ship stern shaft sealing device with pressure equalization

Abstract

This utility model discloses a pressure-balanced stern shaft sealing device for ships, including a stern shaft sealing sleeve, a stern shaft sealing seat, and four stern shaft sealing rings installed on the stern shaft. The outer annular cavity between the two outermost stern shaft sealing rings is filled with lubricating fluid. A liquid bladder device is provided outside the stern shaft sealing seat. A flexible liquid bladder and a liquid bladder pressurizing piston are sequentially arranged inside the outer shell of the liquid bladder device. The outer annular cavity communicates with the inner cavity of the flexible liquid bladder, and the outer side of the liquid bladder pressurizing piston communicates with the outer side of the liquid bladder shell. The inner annular cavity between the two innermost stern shaft sealing rings is filled with cooling lubricating oil, and compressed air is injected into the intermediate annular cavity between the two middle stern shaft sealing rings. This pressure-balanced stern shaft sealing device can automatically maintain the pressure difference between the two sides of the stern shaft water seal rings within a certain range regardless of changes in draft, thus ensuring the stern shaft sealing device is in a relatively ideal working state.

Description

Technical Field

[0001] This utility model relates to a marine accessory, and more particularly to a sealing device for a ship's stern shaft. Background Technology

[0002] A stern shaft sealing device is used to seal the stern shaft, which extends beyond the hull, to prevent water from entering the hull and to prevent the lubricating oil of the stern shaft bearing from leaking out. A commonly used stern shaft sealing device employs a four-lip seal ring structure. These four seal rings are spaced apart between the stern shaft sealing seat, which is fixed to the hull, and the stern shaft sealing sleeve, which is fixed to the stern shaft. The two seal rings adjacent to the propeller are water seal rings to prevent water from entering the ship, while the other two seal rings adjacent to the stern shaft tube are oil seal rings to prevent the lubricating oil of the stern shaft bearing inside the stern shaft tube from leaking out. A lip seal mainly consists of an elastic sealing body and its inner sealing lip. The lip seal forms a seal by relying on the elasticity of the elastic sealing body to bring the lip into contact with the shaft surface. The opening of the lip seal faces the side containing the liquid to be sealed. Normally, the liquid to be sealed is not pressurized, and the other side of the seal is in a natural state at atmospheric pressure. When the weight of the liquid to be sealed acts between the seal and the shaft, the elasticity of the elastic sealing body presses the sealing lip against the shaft, preventing leakage. However, if the liquid to be sealed has a large pressure, it will exert a large force on the elastic sealing body of the seal. This large force will force the lip of the elastic sealing body to deform, and in severe cases, the lip may flip over, thus failing to achieve a seal. Therefore, lip seals require that the pressure on both sides be similar during operation, and the pressure difference between the two sides must not exceed the specified range. To improve the pressure resistance of lip seals, a structure with reinforcing ribs can be used, embedding the highly rigid reinforcing ribs into the elastic sealing body, making the elastic sealing body less prone to deformation under high pressure. However, such lip seals still have certain limitations in terms of pressure resistance, and the reinforcing ribs embedded in the elastic sealing body reduce its elasticity, affecting the elastic force of the lip on the shaft, which is not ideal for applications with inconsistent pressure. For the sealing conditions of ship stern shafts, especially large transport ships, due to the difference in draft between full load and empty load, the water depth pressure of the external water body borne by the water seal adjacent to the propeller is frequently and significantly varied. Therefore, the commonly used structure of ship stern shaft sealing devices mentioned above still needs improvement. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a ship stern shaft sealing device with pressure balance, which can automatically maintain the pressure difference on both sides of the ship stern shaft water seal ring within a certain range regardless of the change of draft, so that the stern shaft sealing device is in a more ideal working state.

[0004] To solve the above-mentioned technical problems, this utility model provides a pressure-balanced ship stern shaft sealing device, including a stern shaft sealing sleeve and a stern shaft sealing seat sealed and installed on the stern shaft. Four stern shaft sealing rings are disposed between the stern shaft sealing sleeve and the stern shaft sealing seat. The outer annular cavity between the two outermost stern shaft sealing rings is filled with lubricating fluid. A liquid bladder device is provided outside the stern shaft sealing seat. A flexible liquid bladder is housed inside the outer shell of the liquid bladder device. The outer annular cavity communicates with the inner cavity of the flexible liquid bladder. A liquid bladder pressurizing piston is also provided inside the liquid bladder shell. The flexible liquid bladder is located in the cavity between the inner side of the liquid bladder pressurizing piston and the liquid bladder shell. The outer side of the liquid bladder pressurizing piston communicates with the outer side of the liquid bladder shell. The inner annular cavity between the two innermost stern shaft sealing rings is filled with cooling lubricating oil, and compressed air is injected into the intermediate annular cavity between the two middle stern shaft sealing rings.

[0005] In the above structure, since the outer end annular cavity between the two outermost stern shaft seals is filled with lubricating fluid, and a liquid bladder device is provided outside the stern shaft seal seat, and a flexible liquid bladder is provided inside the liquid bladder shell of the liquid bladder device, the outer end annular cavity and the inner cavity of the flexible liquid bladder device are connected, the flexible liquid bladder of the liquid bladder device and the outer end annular cavity are filled with lubricating fluid. This flowing oil can lubricate the water seals on both sides of the outer end annular cavity, and can also have a certain pressure to provide support and balance for the outermost water seal, so that the pressure difference on both sides of the outermost water seal is maintained at a certain level to ensure that the water seal can work normally.

[0006] Furthermore, since a liquid-filled bladder pressurizing piston is also provided inside the liquid-filled bladder shell, and the flexible liquid-filled bladder is located in the cavity between the inner side of the pressurizing piston and the liquid-filled bladder shell, and the outer side of the pressurizing piston is connected to the outer side of the liquid-filled bladder shell, the outer side of the pressurizing piston will bear the pressure of the water depth at which the ship's stern shaft is located outside the liquid-filled bladder shell. Under the action of this water depth pressure, the pressurizing piston will press against the flexible liquid-filled bladder, and the lubricating fluid inside the flexible liquid-filled bladder will be compressed, thus increasing the pressure of the lubricating fluid. Due to the frictional resistance between the pressurizing piston and the liquid-filled bladder shell, as well as the deformation resistance of the flexible liquid-filled bladder itself, the pressure of the lubricating fluid will be less than the pressure at the water depth at which the ship's stern shaft is located. This means the pressure difference between the outermost water seal ring and the water depth at the stern shaft is less than the pressure exerted by the outermost water seal ring. This ensures that the pressure difference between the inner and outer sides of the water seal ring is within the allowable pressure difference range of the lip seal ring. This pressure difference can be maintained regardless of whether the ship is fully loaded or empty, without the need for manual or special control devices to adjust the pressure difference. This ensures that the water seal ring is always in ideal working condition, avoiding the possibility of the lip seal ring being flipped, deformed, or damaged due to a large pressure difference on both sides. This improves the service life of the water seal ring and effectively prevents water from outside the stern shaft from entering the ship through the sealing device.

[0007] Furthermore, since the inner end annular cavity between the two innermost stern shaft seals is filled with cooling lubricating oil, and the middle annular cavity between the two middle stern shaft seals is filled with compressed air, the compressed air injected into the middle annular cavity can increase the pressure on one side of the inner water seal, thereby balancing the pressure of the lubricating fluid in the outer annular cavity. Moreover, the pressure difference between the two sides of the inner water seal can be maintained within the allowable range by adjusting the pressure value of the compressed air. Similarly, the cooling lubricating fluid filled in the inner end annular cavity has a certain pressure, and its pressure value can be adjusted to be lower than the pressure of the compressed air in the middle annular cavity, so that the pressure difference between the two sides of the outer oil seal can be maintained within the allowable range. For the innermost oil seal, its inner side contains the lubricating oil of the ship's stern shaft bearing, which itself has a certain pressure. Under normal circumstances, the pressure of the lubricating oil injected into the inner end annular cavity can balance it. In this way, by adjusting the pressure of the lubricating fluid pressurized by the external water in the outer ring cavity, the pressure of the compressed air injected into the middle ring cavity, and the pressure of the cooling lubricating oil injected into the inner ring cavity, the pressure difference on both sides of each water seal ring and oil seal ring can be maintained within a certain range, and the entire stern shaft sealing device can be in a relatively ideal working state.

[0008] In a preferred embodiment of this invention, the lubricant is water. Using water as the lubricant for the water seal ring in this embodiment provides both lubrication and cooling, while eliminating the risk of contamination after leakage, thus meeting the usage requirements.

[0009] In another preferred embodiment of this invention, the outer annular cavity is connected to the inner cavity of the flexible liquid bladder via a lubricating fluid communication hole, which is radially disposed on the side wall of the stern shaft seal. This embodiment facilitates the connection between the outer annular cavity and the inner cavity of the flexible liquid bladder, as well as the installation and connection of the outer liquid bladder device.

[0010] In another preferred embodiment of this invention, the outer annular cavity is connected to a fluid replenishment device inside the ship's compartment. This embodiment allows for timely replenishment of lubricating fluid in the outer annular cavity should there be leakage, ensuring sufficient lubricating fluid in the fluid bladder and enabling the lubricating fluid in the outer annular cavity to provide adequate pressure balance support for the water seal ring.

[0011] In a further preferred embodiment of this invention, the fluid replenishment connection hole connecting the outer annular cavity to the fluid replenishment device inside the ship's compartment is located within the side wall of the stern shaft seal. With this embodiment, the connection channel between the fluid replenishment device and the outer annular cavity is unaffected by any objects, ensuring unobstructed passage.

[0012] In another preferred embodiment of this invention, a drain hole is provided at the bottom of the stern shaft sealing seat in the intermediate annular cavity. The drain hole is connected to a drain container inside the hull via a corresponding drain connecting hole. With this embodiment, regardless of which side of the sealing ring leaks or is damaged, the leaked oil or water can flow to the drain container inside the hull. Monitoring the drain window allows for timely detection of the stern shaft sealing device's operating status, and timely maintenance can be performed if problems arise.

[0013] In another preferred embodiment of this invention, the outer side of the liquid bladder pressurizing piston is connected to the outer side of the liquid bladder housing via a filter mounted on the liquid bladder housing. This embodiment prevents impurities in the water from entering the piston chamber, ensuring the normal operation of the liquid bladder pressurizing piston.

[0014] In a further preferred embodiment of this invention, the outer periphery of the liquid bladder pressurizing piston is sealed to the inner wall of the liquid bladder shell via two piston sealing rings. This embodiment effectively prevents potential leakage between the liquid bladder pressurizing piston and the inner wall of the liquid bladder shell.

[0015] In another further preferred embodiment of this invention, the piston seal is an O-ring with a rectangular cross-section. Using this embodiment, the rectangular O-ring provides better leak-proof performance than a circular O-ring.

[0016] In a further preferred embodiment of this invention, the inner annular cavity is connected to a lubricating oil supply device within the ship's hold, and the intermediate annular cavity is connected to a compressed air source within the ship's hold. This embodiment ensures a reliable supply of cooling lubricating oil to the inner annular cavity and lubricating fluid to the intermediate annular cavity, as well as pressure regulation. Attached Figure Description

[0017] The following detailed description of the pressure-balanced ship stern shaft sealing device of this utility model, with reference to the accompanying drawings and specific embodiments, is provided in further detail.

[0018] Figure 1 This is a schematic diagram of a specific embodiment of the pressure-balanced ship stern shaft sealing device of this utility model;

[0019] Figure 2 yes Figure 1 An enlarged schematic diagram of the liquid bladder device in the structure shown.

[0020] In the diagram: 1-Stern shaft, 2-Stern shaft sealing sleeve, 3-Stern shaft sealing seat, 4-Stern shaft sealing ring, 5-Outer end annular cavity, 6-Lubricating fluid connecting hole, 7-Liquid bladder device, 8-Flexible liquid bladder, 9-Liquid bladder outer shell, 10-Liquid bladder pressurizing piston, 11-Intermediate annular cavity, 12-Inner end annular cavity, 13-Replenishment fluid connecting hole, 14-Drainage hole, 15-Drainage connecting hole, 16-Piston sealing ring, 17-Filter. Detailed Implementation

[0021] exist Figure 1 In the pressure-balanced stern shaft sealing device shown, the stern shaft sealing sleeve 2 is sealed and fixedly installed on the stern shaft 1. A stern shaft sealing seat 3 is fitted around the outer periphery of the stern shaft sealing sleeve 2. The stern shaft sealing seat 3 is sealed and fixedly installed on the hull of the ship. Four stern shaft sealing rings 4 are installed between the stern shaft sealing sleeve 2 and the stern shaft sealing seat 3. The stern shaft sealing rings 4 are lip sealing rings. In order to facilitate the installation of the stern shaft sealing rings 4, the stern shaft sealing seat 3 is composed of several seat sections that are sealed and connected along the axial direction by sealing gaskets or sealing rings. Each seat section is fixedly connected as a whole by connecting bolts. Each stern shaft sealing ring 4 is installed in the corresponding seat section. The two outermost stern shaft sealing rings 4 are water-sealing rings. The outer annular cavity 5 between the two outermost stern shaft sealing rings 4 is filled with lubricant, preferably water. A liquid bladder device 7 is provided outside the stern shaft sealing seat 3. The liquid bladder device 7 is mounted and fixed to the stern shaft sealing seat 7. A flexible liquid bladder 8 is provided inside the liquid bladder shell 9 of the liquid bladder device 7. The outer annular cavity 5 communicates with the inner cavity of the flexible liquid bladder 8 through a lubricant communication hole 6 radially provided on the side wall of the stern shaft sealing seat 7 and a corresponding interface. See also... Figure 2 A liquid bladder pressurizing piston 10 is also provided inside the liquid bladder shell 9. The outer periphery of the liquid bladder pressurizing piston 10 is sealed to the inner wall of the liquid bladder shell 9 through two piston sealing rings 16. The piston sealing rings 16 are preferably O-rings with a rectangular cross-section. The flexible liquid bladder 8 is located in the cavity between the inner side of the liquid bladder pressurizing piston 10 and the liquid bladder shell 9. The outer side of the liquid bladder pressurizing piston 10 is connected to the outer side of the liquid bladder shell 9 through a filter 17 installed on the liquid bladder shell 9. The filter 17 can simply be a mesh filter. The outer end annular cavity 5 is connected to the liquid replenishment device (not shown in the figure) in the ship's tank. The liquid replenishment communication hole 13 between the outer end annular cavity 5 and the liquid replenishment device in the ship's tank is provided in the side wall of the stern shaft sealing seat 7.

[0022] The two innermost stern shaft seals 4 are oil seals. The inner annular cavity 12 between the two innermost stern shaft seals 4 is filled with cooling lubricating oil, and the inner annular cavity 12 is connected to the lubricating oil supply device (not shown in the figure) in the ship's hold. Compressed air is injected into the intermediate annular cavity 11 between the two middle stern shaft seals 4, and the intermediate annular cavity 11 is connected to the compressed air source (not shown in the figure) in the ship's hold. A drain hole 14 is provided at the bottom of the stern shaft seal seat 7 at the intermediate annular cavity 11, and the drain hole 14 is connected to the drain container (not shown in the figure) in the ship's hold through a corresponding drain connecting hole 15.

[0023] The above are only some preferred embodiments of this utility model, but this utility model is not limited thereto, and many improvements and modifications can be made. Any improvements and modifications made based on the basic principles of this utility model should be considered to fall within the protection scope of this utility model.

Claims

1. A pressure-balanced stern shaft sealing device for a ship, comprising a stern shaft sealing sleeve (2) and a stern shaft sealing seat (3) sealed and installed on the stern shaft (1), and four stern shaft sealing rings (4) disposed between the stern shaft sealing sleeve (2) and the stern shaft sealing seat (3), characterized in that: The outer end annular cavity (5) between the two outermost stern shaft seals (4) is filled with lubricating fluid. A liquid bladder device (7) is provided outside the stern shaft seal seat (3). A flexible liquid bladder (8) is provided inside the liquid bladder shell (9) of the liquid bladder device (7). The outer end annular cavity (5) is connected to the inner cavity of the flexible liquid bladder (8). A liquid bladder pressurizing piston (10) is also provided inside the liquid bladder shell (9). The flexible liquid bladder (8) is located in the cavity between the inner side of the liquid bladder pressurizing piston (10) and the liquid bladder shell (9). The outer side of the liquid bladder pressurizing piston (10) is connected to the outer side of the liquid bladder shell (9). The inner end annular cavity (12) between the two innermost stern shaft seals (4) is filled with cooling lubricating oil. Compressed air is injected into the middle annular cavity (11) between the two middle stern shaft seals (4).

2. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: The lubricant is water.

3. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: The outer end annular cavity (5) is connected to the inner cavity of the flexible liquid bladder (8) through the lubricating fluid communication hole (6), and the lubricating fluid communication hole (6) is radially disposed on the side wall of the stern shaft seal seat (3).

4. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: The outer end annular cavity (5) is connected to the liquid replenishment device inside the ship's cabin.

5. The pressure-balanced ship stern shaft sealing device according to claim 4, characterized in that: The fluid replenishment connection hole (13) connecting the outer end annular cavity (5) with the fluid replenishment device in the ship's cabin is located inside the side wall of the stern shaft sealing seat (3).

6. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: A drain hole (14) is provided at the bottom of the stern shaft seal seat (3) in the intermediate annular cavity (11). The drain hole (14) is connected to the drain container in the cabin through the corresponding drain connecting hole (15).

7. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: The outer side of the liquid bladder pressurizing piston (10) is connected to the outer side of the liquid bladder housing (9) through a filter (17) installed on the liquid bladder housing (9).

8. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: The outer periphery of the liquid bladder pressurizing piston (10) is sealed to the inner wall of the liquid bladder shell (9) through two piston sealing rings (16).

9. The pressure-balanced ship stern shaft sealing device according to claim 8, characterized in that: The piston seal (16) is an O-ring with a rectangular cross-section.

10. The pressure-balanced ship stern shaft sealing device according to claim 1, characterized in that: The inner end annular cavity (12) is connected to the lubricating oil supply device in the cabin, and the middle annular cavity (11) is connected to the compressed air source in the cabin.

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