A stern shaft sealing device for a ship

Abstract

The application discloses a marine stern shaft sealing device and relates to the technical field of ship equipment. The device comprises a stern shaft cylinder, a stern shaft, a silt interception assembly, a first sealing unit and a pipeline system. The stern shaft penetrates through the stern shaft cylinder and is rotationally connected through a bearing, and a sealing structure is arranged in the interval between the two. The first sealing unit comprises four sealing cups arranged in the axial direction, which divide the interval into a first mounting cavity, a gas cavity, a second mounting cavity and a cooling liquid cavity. The pipeline system is in communication with the gas cavity and the cooling liquid cavity respectively to maintain pressure. The core lies in a buffer structure in the first mounting cavity and the second mounting cavity, which comprises a sealing ring, an adjusting assembly and an abutting assembly. When the seawater pressure suddenly increases, the buffer structure converts the impact kinetic energy into elastic potential energy and gas compression potential energy through elastic deformation, pressure conduction and the like, realizes pressure buffering, dynamically enhances the sealing performance, prevents seawater from flowing back, guarantees the safety of ship navigation, and improves the reliability and stability of the sealing device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of stern shaft sealing machinery, and relates to a marine stern shaft sealing device. BACKGROUND

[0002] The marine stern shaft sealing device is a key barrier between the marine power system and the watertight cabin, and its core function is to prevent seawater outside the ship from penetrating into the ship body and to prevent lubricating oil, cooling liquid and other media inside the ship from leaking into the marine environment, which is directly related to the navigation safety of the ship, the service life of the equipment and the ecological environmental protection.

[0003] The current mainstream stern shaft sealing technology mainly adopts a multi-layer sealing skin bowl combined structure to realize sealing through close adhesion of the skin bowl lip to the rotating stern shaft.

[0004] However, in the actual operation of the ship, the combined structure has the following problems: when the ship is sailing, the stern shaft sealing area always bears a complex pressure environment. In severe sea conditions (typhoon, huge waves, etc.) or ship maneuvering operation (emergency acceleration, deceleration, turning, etc.), the seawater pressure outside the ship will instantaneously increase, far exceeding the bearing limit of the conventional sealing skin bowl. At this time, the sealing skin bowl lip may be deformed and warped due to the instantaneous pressure difference, causing seawater to quickly flow back through the gap; at least the ship's internal medium is contaminated, increasing the equipment maintenance cost; at most the cabin is flooded, threatening the buoyancy and stability of the ship. SUMMARY

[0005] To solve the problems in the background art, the present application provides a marine stern shaft sealing device.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a marine stern shaft sealing device, comprising a stern shaft cylinder and a stern shaft rotatably installed therein, wherein the stern shaft cylinder is provided with an air duct and a liquid duct; there is a gap between the stern shaft cylinder and the stern shaft, and a first sealing unit is installed in the gap;

[0007] The first sealing unit comprises four sealing skin bowls, which are sequentially arranged in the axial direction and divide the cavity between the stern shaft cylinder and the stern shaft into a first installation cavity, a gas cavity, a second installation cavity and a cooling liquid cavity; the air duct is in communication with the gas cavity, and the liquid duct is in communication with the cooling liquid cavity;

[0008] The first sealing unit further comprises two buffer structures, which are respectively installed in the first installation cavity and the second installation cavity, and the buffer structures are used to buffer the increased seawater pressure, so that the gas cavity and the cooling liquid cavity are dynamically balanced with the external seawater pressure;

[0009] The buffer structure comprises a sealing sleeve ring, an adjusting assembly and an abutting assembly;

[0010] The sealing ring is coaxially sleeved outside the stern shaft; the adjusting assembly is sleeved outside the sealing ring and is used for adjusting the buffer damping; the abutting assembly is installed on the sealing ring and is used for keeping the sealing ring abutting against the stern shaft;

[0011] The sealing ring comprises an elastic sealing sleeve; the elastic sealing sleeve is coaxially sleeved on the stern shaft;

[0012] Two sealing plates are respectively fixed at two ends of the elastic sealing sleeve along the axial direction;

[0013] Two elastic sleeves correspond to the two sealing plates, the two elastic sleeves are fixedly connected with the corresponding sealing plates, and the elastic sleeves are fixedly connected with the stern shaft sleeve.

[0014] Preferably, the sealing cup has a concave opening, the concave openings of the three sealing cups closest to the outside of the ship body face the outside of the ship body, and the concave opening of the sealing cup closest to the ship body faces the ship body.

[0015] Preferably, the adjusting assembly comprises an outer sleeve, the outer sleeve is coaxially sleeved outside the sealing ring and is fixedly connected with the stern shaft sleeve;

[0016] An inner sleeve is fixedly connected with the outer sleeve in a coaxial manner, and an annular chamber is formed between the inner sleeve and the outer sleeve;

[0017] An annular piston plate is slidably installed in the annular chamber between the inner sleeve and the outer sleeve, and the annular piston plate divides the annular chamber into a first buffer cavity and a second buffer cavity.

[0018] Preferably, a first connecting pipe is arranged on the annular piston plate, and an end portion of the outer sleeve is provided with a second connecting pipe; the axes of the first connecting pipe and the second connecting pipe are parallel to the axis of the stern shaft;

[0019] In the buffer structure of the first mounting cavity, the second connecting pipe is in communication with the gas cavity; in the buffer structure of the second mounting cavity, the first connecting pipe is in communication with the gas cavity.

[0020] Preferably, a first spring is sleeved on the first connecting pipe, one end of the first spring is fixed to the annular piston plate, and the other end of the first spring is fixed to the end portion of the outer sleeve.

[0021] Preferably, there is a gap between the sealing ring and the adjusting assembly, and the abutting assembly is installed in the gap between the sealing ring and the adjusting assembly.

[0022] Preferably, the abutting assembly comprises an annular elastic sleeve, the annular elastic sleeve is installed in the gap between the sealing ring and the adjusting assembly, and the two ends of the gap between the sealing ring and the adjusting assembly abut against the sealing plates;

[0023] A plurality of top rods are arranged, a plurality of sleeves are arranged on the middle circumferences of the annular elastic cylinders and arranged along the radial direction of the stern shaft, the top rods correspond to the sleeves one by one, the top rods are slidably arranged in the sleeves through the second springs, and the end of the top rod abuts against the inner wall of the sealing sleeve ring.

[0024] Preferably, the end of the top rod abutting against the inner wall of the sealing sleeve ring is in the form of an elastic member.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1. The impact of seawater pressure is effectively buffered: by arranging a unique buffering structure between the sealing cups, the impact kinetic energy of seawater can be quickly converted into elastic potential energy and gas compression potential energy when the seawater pressure suddenly increases, thereby greatly relieving the impact of high-pressure seawater on the sealing device and preventing seawater from flowing into the ship body, thereby ensuring the safety of ship navigation.

[0027] 2. The pressure balance of the sealing device is maintained: the optimized pipeline system and pressure control mode ensure that the pressure of the gas cavity and the cooling liquid cavity is always stable and reasonable during normal ship operation, and can be automatically adjusted according to the change of seawater pressure, thereby maintaining the good sealing effect of the sealing cup and timely treating the infiltrated seawater and cooling liquid to avoid the adverse effects of mixed liquid on the sealing device.

[0028] 3. The sealing performance is enhanced: the cooperation of the sealing sleeve ring and the abutting assembly can ensure good sealing effect under normal working conditions and dynamically enhance the sealing performance when the seawater pressure suddenly increases, thereby further preventing seawater leakage and improving the reliability and stability of the stern shaft sealing device. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the three-dimensional structure of the present application;

[0030] Figure 2 is a schematic diagram of the main view cross-sectional structure of the present application;

[0031] Figure 3 is a schematic diagram of the structure of the connection between the sealing cup and the stern shaft of the present application;

[0032] Figure 4 is a schematic diagram of the structure of the connection between the first sealing unit and the stern shaft of the present application;

[0033] Figure 5 is a schematic diagram of the structure of the installation between the sealing sleeve ring and the adjusting assembly of the present application;

[0034] Figure 6 is a schematic diagram of the structure of the sealing sleeve ring of the present application;

[0035] Figure 7is a structural schematic diagram of the installation between the adjusting assembly and the abutting assembly of the present application;

[0036] Figure 8 is a cross-sectional structural schematic diagram of the installation between the adjusting assembly and the abutting assembly of the present application;

[0037] Figure 9 is a structural schematic diagram of the abutting assembly of the present application Figure 8 is an enlarged view of the cross-sectional structure at A in the present application;

[0038] Figure 10 is a structural schematic diagram of the abutting assembly of the present application;

[0039] Figure 11 is a working state schematic diagram of the buffer structure in the present application.

[0040] In the figure: 1, stern shaft tube; 101, bearing; 102, first installation slot; 103, second installation slot; 2, stern shaft; 21, first installation cavity; 22, gas cavity; 23, second installation cavity; 24, cooling liquid cavity; 3, first sealing unit; 31, sealing cup; 311, first sealing cup; 312, second sealing cup; 313, third sealing cup; 314, fourth sealing cup; 32, sealing collar; 321, sealing plate; 3211, first sealing plate; 3212, second sealing plate; 3213, third sealing plate; 3214, fourth sealing plate; 322, elastic sealing sleeve; 323, elastic cylinder; 33, adjusting assembly; 331, outer cylinder; 332, inner cylinder; 333, first connecting pipe; 334, second connecting pipe; 335, annular piston plate; 3351, first annular piston plate; 3352, second annular piston plate; 336, liquid outlet hole; 337, first spring; 338, first buffer cavity; 3381, seawater buffer cavity; 3382, second gas buffer cavity; 339, second buffer cavity; 3391, first gas buffer cavity; 3392, cooling liquid buffer cavity; 34, abutting assembly; 341, annular elastic cylinder; 342, sleeve; 343, top rod; 344, second spring; 4, silt interception assembly; 5, air inlet pipe; 6, air outlet pipe; 7, liquid inlet pipe; 8, liquid outlet pipe. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0042] As Figures 1 to 11As shown, the technical solution adopted by the present invention is as follows: a marine stern shaft sealing device. It includes a stern shaft cylinder 1, a stern shaft 2, a sediment interception assembly 4, a first sealing unit 3, and related piping systems. The stern shaft cylinder 1 is fixedly connected to the hull as a fixed component. The stern shaft 2 passes through the stern shaft cylinder 1 and is rotatably connected to the stern shaft cylinder 1 via a bearing 101. A gap exists between the stern shaft cylinder 1 and the stern shaft 2, and a sealing structure is installed within this gap.

[0043] The stern shaft cylinder 1 has a second mounting groove 103, and the mud and sand interception component 4 is mounted on the second mounting groove 103. The mud and sand interception component 4 is used to intercept mud and sand or impurities, preventing them from entering the gap between the stern shaft 2 and the stern shaft cylinder 1, thereby protecting the first sealing unit 3. The mud and sand interception component 4 is prior art and will not be described in detail here.

[0044] like Figure 3 As shown, the first sealing unit 3 includes four sealing cups 31. The four sealing cups 31 are detachably installed on the inner wall of the stern shaft cylinder 1, and are arranged sequentially along the axial direction of the stern shaft cylinder 1. The four sealing cups 31 are named sequentially from the side closest to the seawater outside the ship to the inside of the ship: first sealing cup 311, second sealing cup 312, third sealing cup 313, and fourth sealing cup 314.

[0045] The sealing cup 31 is existing technology. Each sealing cup 31 has a concave opening, which forms the lip of the sealing cup 31. The lips of the first sealing cup 311, the second sealing cup 312, and the third sealing cup 313 all face the seawater outside the ship, while the lip of the fourth sealing cup 314 faces the inward direction of the ship.

[0046] When the stern shaft 2 rotates, the lips of these sealing cups 31 remain in contact with the shaft surface of the stern shaft 2 under the action of their own elastic force. At the same time, for the first sealing cup 311, the second sealing cup 312, and the third sealing cup 313 with their lips facing the seawater outside the ship, the pressure of the external seawater will further press the lips against the shaft surface, enhancing the sealing effect; the fourth sealing cup 314 facing the inside of the ship will be subjected to the pressure of the medium inside the ship, which will also make the lips fit more tightly against the shaft surface, thereby preventing seawater from seeping into the ship or the medium inside the ship from leaking out into the sea.

[0047] like Figure 3As shown, the four sealing cups 31 divide the cavity between the stern shaft tube 1 and the stern shaft 2 into multiple chambers. From the side close to the seawater outside the ship, the chamber between the first sealing cup 311 and the second sealing cup 312 is the first installation cavity 21, and the chamber between the second sealing cup 312 and the third sealing cup 313 is the gas cavity 22. The chamber between the third sealing cup 313 and the fourth sealing cup 314 is the second installation cavity 23. The chamber away from the side close to the ship body of the fourth sealing cup 314 is the cooling liquid cavity 24.

[0048] As shown in Figure 2 , Figure 3 , the pipeline system includes a gas pipeline and a cooling liquid pipeline. The gas pipeline includes an air inlet pipe 5 and an air outlet pipe 6. The air inlet pipe 5 and the air outlet pipe 6 are both in communication with the gas cavity 22 and are both in communication with a gas supply system. The cooling liquid pipeline includes a liquid inlet pipe 7 and a liquid outlet pipe 8. The liquid inlet pipe 7 and the liquid outlet pipe 8 are both in communication with the cooling liquid cavity 24 and are both in communication with a cooling liquid system. Among them, the gas supply system and the cooling liquid system are prior art, and will not be described in detail here.

[0049] When the ship is normally running, inert gas is introduced into the gas cavity 22, and the inert gas can be selected as nitrogen. The inert gas pressure is set to be 0.1-0.3 MPa lower than the external seawater pressure. Under the action of this pressure difference, the seawater pressure will push the lip of the first sealing cup 311 to tightly fit the stern shaft 2. At the same time, the pressure in the cooling liquid cavity 24 is set to be higher than that in the gas cavity 22. Under the action of the pressure difference between the cooling liquid cavity 24 and the gas cavity 22, the cooling liquid pressure will push the lip of the fourth sealing cup 314 to tightly fit the stern shaft 2, forming an inner sealing barrier.

[0050] Because there is dynamic friction between the lip of the sealing cup 31 and the stern shaft 2 during the running of the ship, and there is a small gap between the sealing surfaces, a small amount of seawater will inevitably penetrate from the fitting surface between the first sealing cup 311 and the stern shaft 2 into the first installation cavity 21, and further into the gas cavity 22 through the gap of the second sealing cup 312. At the same time, the cooling liquid in the cooling liquid cavity 24 will also penetrate into the gas cavity 22 through the gap between the fourth sealing cup 314 and the third sealing cup 313 due to the pressure difference, so that the seawater and the cooling liquid are mixed in the gas cavity 22. After the seawater and the cooling liquid are mixed in the gas cavity 22, they are timely transported to the on-board treatment system through the air outlet pipe 6, so as to maintain the stable pressure environment of the gas cavity 22.

[0051] It should be noted that the cooperation of the sealing cup 31 and the gas pipeline and the cooling liquid pipeline is a common sealing technology in the prior art, and only a brief description of the above sealing technology is made in this application, and no detailed description is made.

[0052] The core of this application is: a buffer structure is set between the sealing cups 31. When the seawater pressure on the stern shaft 2 suddenly increases, the buffer structure buffers the seawater in time to prevent seawater from flowing back into the hull from the installation point of the stern shaft cylinder 1 and the stern shaft 2, thereby affecting normal navigation.

[0053] Specifically, such as Figure 2 As shown, a buffer structure is installed in both the first mounting cavity 21 and the second mounting cavity 23. A first mounting groove 102 is provided on the inner wall of the stern shaft cylinder 1 corresponding to the first mounting cavity 21 and the second mounting cavity 23, and the two buffer structures are respectively installed in these two first mounting grooves 102.

[0054] The buffer structure includes a sealing ring 32, an adjusting component 33, and an abutment component 34. The buffer structure is primarily used to absorb the impact of high-pressure seawater and prevent seawater from flowing back into the hull. Seawater impact or acceleration of the hull can generate locally high-pressure seawater.

[0055] like Figures 4 to 6 As shown, the sealing ring 32 is coaxially sleeved on the stern shaft 2. The sealing ring 32 includes two sealing plates 321, one elastic sealing sleeve 322, and two elastic cylinders 323.

[0056] The elastic sealing sleeve 322 is fitted onto the stern shaft 2. Two sealing plates 321 are located at both ends of the elastic sealing sleeve 322 along its axis and are fixedly connected to the corresponding ends of the elastic sealing sleeve 322. The sealing plates 321 are slidably connected to the stern shaft cylinder 1. Two elastic cylinders 323 correspond one-to-one with the two sealing plates 321. Two flanges are fixedly installed inside each first mounting groove 102 by bolts. The two flanges in each first mounting groove 102 correspond one-to-one with the two elastic cylinders 323 in the corresponding first mounting groove 102. One end of the elastic cylinder 323 is fixedly installed on the flange on the corresponding side, and the other end is coaxially fixedly connected to the corresponding sealing plate 321. The elastic cylinder 323 is elastic in the axial direction and can expand and contract under axial pressure. The elastic cylinder 323 can be made of rubber.

[0057] The sealing plate 321 and the elastic sealing sleeve 322 together form an auxiliary seal, which can effectively prevent the medium from leaking through the gap between the elastic sealing sleeve 322 and the stern shaft 2. When the seawater pressure in the first mounting cavity 21 increases suddenly, the seawater pressure will act on the right sealing plate 321, pushing the sealing plate 321 to the left. During this process, the elastic sealing sleeve 322 will be axially deformed by pressure. At the same time, the elastic cylinder 323 near the seawater side is stretched, and the elastic cylinder 323 away from the seawater side is compressed, thereby converting part of the impact force of the seawater into elastic potential energy, achieving a preliminary buffering effect. When the seawater pressure decreases, the elastic cylinder 323 will return to its original shape and drive the sealing ring 32 to reset.

[0058] The adjusting assembly 33 is sleeved outside the sealing ring 32 and located between the two sealing plates 321. The adjusting assembly 33 comprises an outer cylinder 331, an inner cylinder 332 and an annular piston plate 335.

[0059] As shown in Figure 4 , Figures 7 to 10 , the outer cylinder 331 is coaxially sleeved outside the elastic sealing sleeve 322 and fixedly connected with the stern shaft cylinder 1. The inner cylinder 332 is coaxially fixedly installed in the outer cylinder 331. An annular chamber is formed between the outer cylinder 331 and the inner cylinder 332. The annular piston plate 335 is slidingly installed in the annular chamber. The annular piston plate 335 divides the annular chamber into two buffer chambers, i.e. a first buffer chamber 338 and a second buffer chamber 339.

[0060] The annular piston plate 335 is fixedly installed with a first connecting pipe 333 which is parallel to the outer cylinder 331. The first connecting pipe 333 penetrates the annular chamber and the corresponding sealing plate 321 and is fixedly connected with the corresponding sealing plate 321. The first connecting pipe 333 is provided with a liquid outlet hole 336 which communicates the first buffer chamber 338 and the first connecting pipe 333. The first connecting pipe 333 is sleeved with a first spring 337, one end of which is fixed on the end face of the annular chamber and the other end of which is fixed on the annular piston plate 335.

[0061] A second connecting pipe 334 is fixedly installed on the side of the annular chamber away from the first connecting pipe 333. The axis of the second connecting pipe 334 is parallel to the axis of the first connecting pipe 333. The second connecting pipe 334 penetrates the annular chamber and is fixedly connected with the corresponding sealing plate 321.

[0062] For convenience of description, as shown in Figure 11 , for the buffer structure installed at the first installation cavity 21, the second buffer chamber 339 close to the gas cavity 22 is named as the first gas buffer chamber 3391 and the first buffer chamber 338 away from the gas cavity 22 is named as the seawater buffer chamber 3381. For the buffer structure installed at the second installation cavity 23, the first buffer chamber 338 close to the gas cavity 22 is named as the second gas buffer chamber 3382 and the second buffer chamber 339 away from the gas cavity 22 is named as the cooling liquid buffer chamber 3392.

[0063] The sealing plate 321 installed on the right side in the first installation cavity 21 is named as the first sealing plate 3211 and the sealing plate 321 installed on the left side in the first installation cavity 21 is named as the second sealing plate 3212. The sealing plate 321 installed on the right side in the second installation cavity 23 is named as the third sealing plate 3213 and the sealing plate 321 installed on the left side in the first installation cavity 21 is named as the fourth sealing plate 3214.

[0064] The annular piston plate 335 installed in the buffer mechanism within the first mounting cavity 21 is designated as the first annular piston plate 3351. The annular piston plate 335 installed in the buffer mechanism within the second mounting cavity 23 is designated as the second annular piston plate 3352.

[0065] In the buffer mechanism installed in the first mounting cavity 21, one end of the first connecting pipe 333 is connected to the seawater buffer cavity 3381, and the other end of the first connecting pipe 333 is connected to the chamber formed by the first sealing cup 311 and the sealing plate 321. The second connecting pipe 334 connects the first gas buffer cavity 3391 and the gas cavity 22. In the buffer mechanism installed in the second mounting cavity 23, the first connecting pipe 333 connects the second gas buffer cavity 3382 and the gas cavity 22. The second connecting pipe 334 connects the coolant buffer cavity 3392 and the coolant cavity 24.

[0066] It should be noted that during normal ship navigation, even if the pressure inside the gas chamber 22 is 0.1 MPa to 0.3 MPa lower than the external seawater pressure, the annular piston plate 335 can still remain stationary. The specific reasons are as follows: Figure 11 As shown, taking the first annular piston plate 3351 in the first mounting cavity 21 as an example, the forces acting on it include: a leftward thrust exerted by the seawater pressure in the seawater buffer cavity 3381, a rightward thrust exerted by the gas pressure in the first gas buffer cavity 3391, and the elastic force generated by the first spring 337. Since the pressure in the seawater buffer cavity 3381 is equal to the external seawater pressure, and the pressure in the first gas buffer cavity 3391 is the same as the pressure in the gas cavity 22, the leftward thrust caused by the seawater pressure should be greater than the rightward thrust caused by the gas pressure. However, the first spring 337 is in a pre-compressed state, which can provide additional rightward elastic force, which precisely compensates for the imbalance caused by the aforementioned pressure difference, thereby keeping the first annular piston plate 3351 stationary under the condition that the resultant force on both sides is zero.

[0067] Similarly, in the second mounting cavity 23, the forces acting on the second annular piston plate 3352 also include multiple components: the thrust generated by the gas pressure in the second gas buffer cavity 3382, the thrust generated by the liquid pressure in the coolant buffer cavity 3392, and the elastic force corresponding to the first spring 337. Under the combined action of these forces, the second annular piston plate 3352 can also achieve force balance and remain stationary.

[0068] When the ship is sailing normally, the pressure in the seawater buffer chamber 3381 is equal to the external seawater pressure; the pressure in the first gas buffer chamber 3391 and the second gas buffer chamber 3382 is the same as the pressure in the gas chamber 22; and the pressure in the coolant buffer chamber 3392 is equal to the pressure in the coolant chamber 24.

[0069] likeFigure 11 As shown, taking the buffer structure in the first installation cavity 21 as an example, when the seawater pressure suddenly increases and rushes into the first installation cavity 21, the seawater pushes the first sealing plate 3211 to move in the direction of the ship body, i.e., to move to the left. The movement of the first sealing plate 3211 increases the volume between the first sealing plate 3211 and the first sealing cup 311, and the preliminary expansion of the volume achieves the preliminary buffering of the seawater pressure.

[0070] At the same time, the left movement of the first sealing plate 3211 pushes the first annular piston plate 3351 to move to the left through the first connecting pipe 333. The movement of the first annular piston plate 3351 causes the chamber volume of the seawater buffer cavity 3381 to increase, and seawater flows into the seawater buffer cavity 3381; at the same time, the volume of the first gas buffer cavity 3391 correspondingly decreases, and the gas in the first gas buffer cavity 3391 is pressed into the gas cavity 22. In this process, the kinetic energy of the seawater impact is converted into the compression potential energy of the gas, and further buffering of the seawater pressure is achieved. In addition, the first spring 337 is stretched with the movement of the first annular piston plate 3351, and stores elastic potential energy, thereby enhancing the buffering effect.

[0071] Similarly, the working principle of the adjusting assembly 33 in the second installation cavity 23 is similar to that of the adjusting assembly 33 in the first installation cavity 21, and the difference lies in that the pipeline connection objects are different: the second gas buffer cavity 3382 is connected with the gas cavity 22 through the first connecting pipe 333, and the cooling liquid buffer cavity 3392 is connected with the cooling liquid cavity 24 through the second connecting pipe 334, which is used to balance the pressure fluctuation between the gas cavity 22 and the cooling liquid cavity 24, and to ensure that the pressure in the cooling liquid cavity 24 changes synchronously with the seawater pressure.

[0072] Specifically, when the gas pressure in the gas cavity 22 rises, the gas pressure pushes the third sealing plate 3213 to move to the left, which increases the volume between the third sealing plate 3213 and the third sealing cup 313, and preliminarily relieves the pressure change. At the same time, the third sealing plate 3213 pushes the second annular piston plate 3352 to move to the left through the first connecting pipe 333, which increases the volume of the second gas buffer cavity 3382, and the gas enters the second gas buffer cavity 3382; the volume of the cooling liquid buffer cavity 3392 decreases, and the cooling liquid in the cooling liquid buffer cavity 3392 is pressed into the cooling liquid cavity 24.

[0073] Through the above linkage mechanism, the increased seawater pressure is sequentially transmitted to the gas cavity 22 and the cooling liquid cavity 24, so that the pressures of the three increase synchronously, adapt to the change of the external seawater pressure, and maintain the dynamic balance of the system, thereby effectively preventing the high-pressure seawater from flowing into the ship body.

[0074] When the seawater impact subsides, the pressure of the cooling liquid cavity 24, the pressure of the gas cavity 22, and the energy storage release of the first spring 337 will act together to drive the annular piston plate 335 to move reversely, so that it returns to the initial position.

[0075] The abutting assembly 34 is installed between the elastic sealing sleeve 322 and the annular chamber. The abutting assembly 34 comprises an annular elastic cylinder 341, a sleeve 342 and a top rod 343.

[0076] The annular elastic cylinder 341 is arranged in a waist-shaped cylinder structure with a smaller middle diameter than the diameters of the two ends. The two ends of the annular elastic cylinder 341 abut against the corresponding sealing plates 321. The sleeve 342 is arranged in multiple and is circumferentially distributed on the inner wall of the annular elastic cylinder 341 on the side close to the elastic sealing sleeve 322. The axis of the sleeve 342 is arranged in the radial direction of the stern shaft 2. The top rod 343 corresponds to the sleeve 342 one by one. The top rod 343 is in sliding connection with the corresponding sleeve 342. The sleeve 342 is fixedly installed with a second spring 344, one end of the second spring 344 is fixed on the top rod 343, and the other end is fixed on the sleeve 342.

[0077] The end of the top rod 343 close to the elastic sealing sleeve 322 is provided with a rubber elastic member. Under the elastic force of the second spring 344, the top rod 343 is pressed against the outer wall of the elastic sealing sleeve 322 through the elastic member at the end in the radial direction of the elastic sealing sleeve 322. When subjected to pressure, the elastic member at the end of the top rod 343 can be deformed, thereby fully adhering to the outer wall of the elastic sealing sleeve 322, thereby increasing the contact area and enhancing the auxiliary sealing effect. The annular elastic cylinder 341 has elasticity. When the elastic sealing sleeve 322 is axially compressed, the two ends of the annular elastic cylinder 341 will move with the movement of the sealing plates 321, the middle part of the annular elastic cylinder 341 will be elastically deformed, so that the middle diameter of the annular elastic cylinder 341 is further reduced, so that the sleeve 342 moves to the side close to the stern shaft 2, the pressure of the second spring 344 increases, and then the pressure of the top rod 343 on the elastic sealing sleeve 322 is increased, further preventing seawater from flowing into the ship body.

[0078] Take the abutting assembly 34 installed in the first installation cavity 21 as an example. When the ship is normally running, the elastic cylinders 323 connected with the two sealing plates 321 are all in the state of extreme compression. Limited by the first installation groove 102, the sealing plate 321 away from the seawater side cannot move to the left, and the sealing plate 321 close to the seawater side cannot move to the right. When the seawater impacts the sealing plate 321 close to the seawater side and moves it to the left, it will push the right end of the annular elastic cylinder 341 to move to the left. Since the left end of the annular elastic cylinder 341 always abuts against the sealing plate 321 away from the seawater side, the left side of the annular elastic cylinder 341 cannot continue to move to the left. At this time, the right end of the annular elastic cylinder 341 deforms under pressure: the right side moves to the left, and the middle part deforms in the direction of reducing the diameter. The deformation pushes the sleeve 342 to move to the side of the stern shaft 2, so that the pressure of the second spring 344 increases, thereby enhancing the pressing force of the top rod 343 on the elastic sealing sleeve 322, further effectively preventing seawater from flowing into the ship body.

[0079] The overall working process is as follows: when the ship is sailing normally, the propeller shaft 2 rotates continuously in the propeller shaft cylinder 1. The gas supply system continuously supplies inert gas, such as nitrogen, into the gas cavity 22 through the gas inlet pipe 5, and the pressure is controlled to be in the range of 0.1-0.3 MPa lower than the external seawater pressure. At the same time, the cooling liquid system injects cooling liquid into the cooling liquid cavity 24 through the liquid inlet pipe 7, and maintains the pressure at a level higher than that of the gas cavity 22.

[0080] Under this stable pressure environment, the lips of the first, second, and third sealing cups 311, 312, and 313 tightly adhere to the rotating propeller shaft 2 under the combined action of their own elastic force and the external seawater pressure, forming multiple sealing barriers towards the outside of the ship. The lip of the fourth sealing cup 314 tightly adheres to the propeller shaft 2 under the action of its own elasticity and the higher pressure of the cooling liquid cavity 24, forming a sealing barrier towards the inside of the ship.

[0081] Due to the dynamic clearance between the sealing cup 31 and the propeller shaft 2, a small amount of seawater can overcome the sealing force of the first sealing cup 311 and seep in through the microscopic gap between the lip of the first sealing cup 311 and the propeller shaft 2, accumulating in the first installation cavity 21. This part of seawater may further seep into the gas cavity 22 through the gap of the second sealing cup 312. At the same time, under the action of the pressure difference, a small amount of cooling liquid in the cooling liquid cavity 24 can also seep into the gas cavity 22 through the gap between the fourth sealing cup 314 and the third sealing cup 313. These two media mix in the gas cavity 22. In order to maintain the set pressure stability of the gas cavity 22 and prevent the accumulation of the mixed liquid, the gas outlet pipe 6 connected to the gas supply system continuously extracts these mixed liquids and transports them to the treatment system on the ship for treatment.

[0082] During normal driving, the two buffer structures are in standby balance state. Taking the buffer structure at the first installation cavity 21 as an example. The annular piston plate 335 is subjected to the leftward thrust from the seawater pressure in the seawater buffer cavity 3381, the rightward thrust from the gas pressure in the first gas buffer cavity 3391, and the rightward elastic force provided by the first spring 337 in the pre-compressed state. These three forces are balanced with each other, so that the annular piston plate 335 remains stationary. The two sealing plates 321 of the sealing sleeve 32 also remain in place under the combined support of the medium pressure on both sides and the elastic cylinder 323. The ball end of the top rod 343 continuously presses against the outer wall of the elastic sealing sleeve 322 in the radial direction under the pre-pressure of the second spring 344, achieving the function of auxiliary sealing.

[0083] When the ship encounters rough working conditions, such as sea wave impact, the sudden and sharp increase of the sea water pressure outside the ship causes the first installation cavity 21 to be impacted by the suddenly increased sea water pressure. The high-pressure sea water first acts on the first sealing plate 3211, pushing it to move to the left. The elastic sealing sleeve 322 fixedly connected with the first sealing plate 3211 is then axially compressed and deformed.

[0084] The leftward movement of the first sealing plate 3211 increases the volume of the cavity between the first sealing plate 3211 and the first sealing bowl 311, generating a certain pressure relief effect. The moving sealing plate 321 pushes the annular piston plate 335 to move synchronously to the left through the first connecting pipe 333.

[0085] The leftward movement of the first annular piston plate 3351 causes the volumes of the two buffer cavities to change: the volume of the sea water buffer cavity 3381 increases, and the volume of the first gas buffer cavity 3391 correspondingly decreases. The sea water is sucked into the expanding sea water buffer cavity 3381 through the liquid outlet hole 336 on the first connecting pipe 333. At the same time, the first gas buffer cavity 3391 with a reduced volume compresses part of the inert gas inside it back into the gas cavity 22 through the pipeline. In this action process, the huge impact kinetic energy of the sea water is converted into the compression potential energy of the gas and the elastic potential energy stored by the further compression of the first spring 337, thereby achieving extremely effective second-stage buffering and flattening the pressure peak.

[0086] At the same time of the action of the sealing sleeve ring 32, the abutting assembly 34 starts to work cooperatively. When the sealing plate 321 moves to cause the elastic sealing sleeve 322 to be axially compressed, the middle part of the annular elastic cylinder 341 abutting against the sealing plate 321 elastically deforms, and the diameter further shrinks. This shrinkage drives the sleeve 342 fixed on the inner wall thereof to move toward the radial center of the stern shaft 2, compressing the second spring 344 in the sleeve 342, thereby increasing the radial pressure of the top rod 343 acting on the elastic sealing sleeve 322. This enhanced pressure forces the elastic sealing sleeve 322 to more closely adhere to the stern shaft 2, dynamically strengthening the sealing effect at this position and effectively preventing the high-pressure sea water from entering at the moment.

[0087] For the buffer structure at the second installation cavity 23, the working principle is similar to the above process. If the pressure fluctuation of the gas cavity 22 caused by the sea water pressure impact affects the balance relationship between the gas cavity 22 and the cooling liquid cavity 24, the adjusting assembly 33 at this position will change the volumes of the second gas buffer cavity 3382 and the cooling liquid buffer cavity 3392 through the movement of the second annular piston plate 3352, thereby absorbing and compensating for the pressure fluctuation, ensuring that the pressure difference on both sides of the fourth sealing bowl 314 remains stable and maintaining the sealing effect.

[0088] When the abnormal seawater impact pressure subsides, the whole system starts to reset under the action of the stored potential energy. The pressure of the gas cavity 22 and the compressed first spring 337 release its stored elastic potential energy, jointly pushing the annular piston plate 335 to move to the right, returning to the initial equilibrium position. The stretched elastic cylinder 323 also returns to its original state, driving the sealing plate 321 and the elastic sealing sleeve 322 of the sealing ring 32 to reset. The annular elastic cylinder 341, the sleeve 342, the top rod 343 and the second spring 344 of the abutting assembly 34 also return to the normal pre-tightening state.

[0089] At this point, the entire device has completed a complete working cycle of coping with pressure impact, and each part cooperates to ensure the reliability of the stern shaft 2 seal.

[0090] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A marine stern shaft sealing device, comprising a stern shaft sleeve (1) and a stern shaft (2) rotatably mounted therein, wherein the stern shaft sleeve (1) is provided with a vent pipe and a liquid pipe; characterized in that: There is a gap between the stern tube (1) and the stern shaft (2), and a first sealing unit (3) is installed in the gap; The first sealing unit (3) includes four sealing cups (31), which are arranged sequentially along the axial direction and divide the cavity between the stern tube (1) and the stern shaft (2) into a first mounting cavity (21), a gas cavity (22), a second mounting cavity (23), and a coolant cavity (24). The vent pipe is connected to the gas cavity (22), and the liquid pipe is connected to the coolant cavity (24). The first sealing unit (3) also includes two buffer structures, which are respectively installed in the first mounting cavity (21) and the second mounting cavity (23). The buffer structures are used to mitigate the increasing seawater pressure, so that the gas cavity (22) and the coolant cavity (24) are dynamically balanced with the external seawater pressure. The buffer structure includes a sealing ring (32), an adjusting component (33), and an abutment component (34). The sealing ring (32) is coaxially sleeved on the outside of the stern shaft (2); the adjusting component (33) is sleeved on the outside of the sealing ring (32) and used to adjust the buffer damping; the abutting component (34) is installed on the sealing ring (32) to keep the sealing ring (32) in contact with the stern shaft (2); The sealing ring (32) includes an elastic sealing sleeve (322); the elastic sealing sleeve (322) is coaxially sleeved on the stern shaft (2); Two sealing plates (321) are fixed at both ends of the elastic sealing sleeve (322) along the axial direction, respectively; Two elastic cylinders (323) correspond one-to-one with two sealing plates (321). The two elastic cylinders (323) are fixedly connected to the corresponding sealing plates (321), and the elastic cylinders (323) are fixedly connected to the stern shaft cylinder (1).

2. The marine stern shaft sealing device according to claim 1, characterized in that: The sealing cup (31) has a concave opening. The concave openings of the three sealing cups (31) closest to the outside of the hull face the outside of the hull, and the concave opening of the sealing cup (31) closest to the hull faces the hull.

3. A marine stern shaft sealing device according to claim 1, characterized in that: The adjustment assembly (33) includes an outer cylinder (331), which is coaxially sleeved on the outside of the sealing ring (32) and fixedly connected to the stern shaft cylinder (1). The inner cylinder (332) is coaxially and fixedly connected to the outer cylinder (331), and an annular cavity is formed between the inner cylinder (332) and the outer cylinder (331); An annular piston plate (335) is slidably installed in the annular cavity between the inner cylinder (332) and the outer cylinder (331), and the annular piston plate (335) divides the annular cavity into a first buffer cavity (338) and a second buffer cavity (339).

4. A marine stern shaft sealing device according to claim 3, characterized in that: The annular piston plate (335) is provided with a first connecting pipe (333), and the end of the outer cylinder (331) is provided with a second connecting pipe (334); the axes of the first connecting pipe (333) and the second connecting pipe (334) are both parallel to the axis of the stern shaft (2); In the buffer structure located in the first mounting cavity (21), the second connecting pipe (334) is connected to the gas cavity (22); in the buffer structure located in the second mounting cavity (23), the first connecting pipe (333) is connected to the gas cavity (22).

5. A marine stern shaft sealing device according to claim 4, characterized in that: A first spring (337) is sleeved on the first connecting pipe (333). One end of the first spring (337) is fixed to the annular piston plate (335), and the other end is fixed to the end of the outer cylinder (331).

6. A marine stern shaft sealing device according to claim 1, characterized in that: There is a gap between the sealing ring (32) and the adjusting component (33), and the abutting component (34) is installed in the gap between the sealing ring (32) and the adjusting component (33).

7. A marine stern shaft sealing device according to claim 6, characterized in that: The abutment component (34) includes an annular elastic cylinder (341), which is installed in the gap between the sealing ring (32) and the adjusting component (33); both ends of the gap between the sealing ring (32) and the adjusting component (33) abut against the sealing plate (321). Multiple push rods (343) are provided. Multiple sleeves (342) are evenly distributed and fixed in the middle circumference of the annular elastic cylinder (341). The sleeves (342) are arranged radially along the stern shaft (2). The push rods (343) correspond one-to-one with the sleeves (342). The push rods (343) are slidably installed in the sleeves (342) by the second spring (344), and the end of the push rods (343) abuts against the inner wall of the sealing ring (32).

8. A marine stern shaft sealing device according to claim 7, characterized in that: The end of the top rod (343) that abuts against the inner wall of the sealing ring (32) is an elastic element structure.

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