Maintenance-free sealing system and electric transmission equipment

Abstract

The invention discloses a maintenance-free sealing system and electric transmission equipment, and relates to the technical field of electric transmission equipment.The maintenance-free sealing system comprises a main shaft sleeve, a body and two sealing assemblies, each sealing assembly comprises a movable sealing ring and a static sealing ring, the main shaft sleeve is used for being fixedly arranged on a main shaft in a sleeving mode, and the main shaft sleeve is used for being fixedly arranged on the main shaft in a sleeving mode; the body is used for being fixedly arranged on a turret shell, the main shaft sleeve is sleeved with the movable sealing rings at intervals in the axial direction of the main shaft sleeve and can rotate along with a main shaft, and the static sealing rings correspond to the movable sealing rings one by one and are arranged on the body and have the freedom degree of moving in the axial direction. The static sealing ring is attached to the end face of the movable sealing ring under the action of preset elastic force to form a sealing pair. A sealing cavity is formed among the two sealing assemblies, the main shaft sleeve and the body; the sealing cavity is used for containing spacer fluid in advance, and the movable sealing ring and the static sealing ring are made of ceramic or hard alloy materials. According to the invention, the long-term, reliable and stable operation of the power transmission channel of the single-point mooring system can be realized.

Description

Technical Field

[0001] This invention relates to the field of electrical transmission equipment technology, and in particular to a maintenance-free sealing system and electrical transmission equipment. Background Technology

[0002] Single-point mooring systems are core equipment in offshore floating production storage and offloading (FPSO) facilities and offshore wind power operation and maintenance. Their turrets require a rotating connection between the hull and underwater cables. High-voltage electrical energy is transmitted through a slip-ring device installed within the turret, which is crucial for ensuring the operation of the upper structure. Since such equipment is typically located at sea level, its electrical transmission channels are filled with insulating media for safety. Therefore, extremely stringent requirements are placed on the sealing performance of the rotating connections: they must be able to effectively seal the internal insulating media for extended periods and withstand the corrosive effects of harsh marine environments such as high salt spray, ultraviolet radiation, and large temperature differences.

[0003] Currently, existing technologies for this type of rotary seal generally employ rotary sealing rings. The most common are seals based on elastic materials (such as rubber), such as skeleton oil seals and O-rings, or packing seals using materials like graphite. To further improve reliability, multiple sealing structures have also emerged, such as combining high-performance polymers with metal seals (such as 316 stainless steel housings) to form multiple sealing barriers.

[0004] However, these existing technical solutions have significant limitations. First, in terms of sealing pressure, traditional sealing structures are typically only suitable for low-pressure conditions (generally below 0.2 MPa), making it difficult to meet the higher medium pressure sealing requirements of higher-power power transmission. Second, in terms of durability, conventional sealing materials are highly susceptible to aging, wear, and failure under long-term salt spray corrosion, ultraviolet aging, high and low temperature alternation, and the uncertain oscillation of the turret, failing to achieve the same design lifespan as the main equipment (e.g., 25 years).

[0005] Therefore, there is an urgent need in this field for an integrated sealing solution that can adapt to high pressure and harsh environments and achieve ultra-long-life maintenance-free operation, in order to overcome the above-mentioned defects of the prior art and ensure the long-term, reliable and stable operation of the electrical transmission channel of the single-point mooring system. Summary of the Invention

[0006] The purpose of this invention is to provide a maintenance-free sealing system and electrical transmission equipment to solve the problems existing in the prior art, and to enable the long-term, reliable and stable operation of the electrical transmission channel of the single-point mooring system.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides a maintenance-free sealing system, including a main shaft sleeve, a body, and two sealing assemblies. Each sealing assembly includes a dynamic sealing ring and a static sealing ring. The main shaft sleeve is fitted and fixed onto a main shaft, and the body is fixedly mounted on a turret housing. The dynamic sealing rings are fitted onto the main shaft sleeve at intervals along its axial direction and can rotate with the main shaft. One static sealing ring corresponds to one dynamic sealing ring. The static sealing ring is disposed on the body and has the freedom to move axially. Under the action of a pre-set elastic force, the static sealing ring fits against the end face of the dynamic sealing ring to form a sealing pair. A sealing cavity is constructed between the two sealing assemblies, the main shaft sleeve, and the body. The sealing cavity is used to pre-fill a separating fluid. The dynamic and static sealing rings are made of ceramic or hard alloy materials.

[0008] Preferably, it further includes a bearing for providing rotational support for the spindle; the bearing is disposed within or outside the sealing cavity; when the bearing is disposed within the sealing cavity, the bearing is located between the two sealing assemblies.

[0009] Preferably, it further includes a sliding bushing, the bearing is disposed in the sealed cavity, the sliding bushing is slidably fitted onto the outside of the main bushing along the axial direction of the main bushing, the sliding bushing is connected to the main bushing via a key; the sliding bushing and the inner ring of the bearing are fixedly connected by an interference fit, the body and the outer ring of the bearing are fixedly connected by an interference fit, the sliding bushing and the inner ring of the bearing form a rotating assembly, the rotating assembly can slide axially on the main bushing to compensate for the thermal expansion and contraction caused by temperature changes between the main bushing and the rotating assembly, at least one of the sealing assemblies has a force transmission structure between the dynamic sealing ring and the rotating assembly, and its installation method allows it to undergo axial displacement to adapt to deformation when subjected to the axial thrust generated by the thermal expansion of the rotating assembly.

[0010] Preferably, it also includes a constant pressure dynamic suppression system, which is used to supply and maintain a pressure of isolation fluid higher than that of the sealed medium to the sealed cavity.

[0011] Preferably, the bearing is disposed in the sealed cavity, and the two sealing assemblies are arranged one above the other, with an isolation ring provided between the upper sealing assembly and the bearing.

[0012] Preferably, the separating fluid is lubricating oil.

[0013] Preferably, the pre-set elastic force comes from a spring built into the body. Under normal conditions, the spring is in a compressed state and one end abuts against the side of the static sealing ring away from the dynamic sealing ring.

[0014] Preferably, the end of the main shaft sleeve closest to the medium has an integrally formed an annular groove facing the static sealing ring, one of the dynamic sealing rings is disposed in the annular groove, and a sealing ring is disposed between the wall of the annular groove and the wall of the dynamic sealing ring; the end of the main shaft sleeve closest to the outside atmosphere is fitted with a drive ring, and the main shaft sleeve and the drive ring are connected to the main shaft by bolts; one end of the drive ring abuts against the end of the sliding shaft sleeve; a limiting part is formed on the drive ring, and the other dynamic sealing ring is fitted on the drive ring and its axial movement away from the static sealing ring is restricted by the limiting part.

[0015] Preferably, the constant pressure dynamic suppression system includes a storage tank, a pressure compensator, a replenishment pump, an isolation fluid tank, monitoring instruments, and a control system; the outlet of the storage tank is connected to the isolation fluid inlet of the sealed cavity via a supply pipeline; the pressure compensator is connected to the storage tank or the supply pipeline for pre-pressurizing and maintaining the stability of the system's base pressure; the inlet of the replenishment pump is connected to the isolation fluid tank, and its outlet is connected to the storage tank; the monitoring instruments include a pressure transmitter, a temperature sensor, and a level sensor; the pressure transmitter is installed on the supply pipeline and / or the storage tank for real-time detection of the isolation fluid pressure; the temperature detection end of the temperature sensor is connected to the isolation fluid outlet of the sealed cavity for real-time monitoring. The system continuously monitors the temperature of the isolation fluid within the sealed cavity; a level sensor is installed inside the isolation fluid tank to monitor the liquid level of the isolation fluid in real time; the control system is signal-connected to the pressure transmitter, temperature sensor, level sensor, and replenishment pump; the control system is configured to: receive signals from the monitoring instruments and control the operation of the replenishment pump accordingly; when the pressure value detected by the pressure transmitter is lower than a first pressure setpoint, control the replenishment pump to start, drawing isolation fluid from the isolation fluid tank and pumping it into the storage tank; when the pressure value reaches a second pressure setpoint higher than the first pressure setpoint, control the replenishment pump to stop; when the level sensor detects that the liquid level is lower or higher than a set range, the control system issues an alarm signal.

[0016] The present invention also provides an electrical transmission device for a single-point mooring system, comprising a turret housing, a main shaft, and a maintenance-free sealing system as described above. The turret housing is filled with a sealing medium, which is an insulating medium. The turret housing has a mounting opening extending along its thickness direction, and the main shaft passes through the mounting opening. The maintenance-free sealing system is sleeved on the main shaft located at the mounting opening and is used to seal the mounting opening.

[0017] The present invention achieves the following technical effects compared to the prior art: First, because the dynamic and static sealing rings are made of ceramic or hard alloy materials, these materials possess extremely high hardness, compressive strength, and resistance to deformation, enabling them to withstand higher medium pressures without irreversible deformation or damage. Furthermore, the static sealing ring has axial freedom of movement and, under preload, fits tightly against the end face of the dynamic ring, ensuring good tracking and contact of the sealing pair even during pressure fluctuations, preventing the sealing interface from opening and leaking due to increased pressure. Therefore, this invention is stably applicable to higher-pressure insulating medium environments (e.g., ≥0.8 MPa), removing the limitations of traditional seals on increasing electrical transmission power and providing higher power transmission assurance for single power generation equipment.

[0018] Secondly, ceramics and cemented carbides are naturally inert to salt spray corrosion and ultraviolet radiation, and their performance will not degrade due to these environmental factors, thus solving the fundamental defects of elastic materials such as easy aging, embrittlement, and cracking. In addition, ceramics and cemented carbides have low coefficients of thermal expansion and good dimensional stability under alternating high and low temperature conditions, avoiding thermal deformation or thermal cracking of the sealing surface due to excessive temperature differences, and ensuring the reliability of sealing performance.

[0019] Third, integrating the bearings and two sets of sealing assemblies into a single unit ensures extremely high coaxiality and installation accuracy, fundamentally reducing uneven wear and abnormal wear caused by alignment errors. Therefore, the sealing assembly system described in this invention has an exceptionally long service life in harsh marine environments, enabling "maintenance-free" operation with the same lifespan as the main equipment, completely avoiding the huge operating costs and production losses caused by frequent shutdowns for seal replacement. Furthermore, the integrated design ensures the concentricity of the bearings and seals; even with oscillations, the entire rotating assembly moves as a whole, with minimal internal relative displacement, protecting the delicate sealing interface. Therefore, the system described in this embodiment can better adapt to the uncertain directional oscillations during turret operation, exhibiting higher operational stability and reliability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a maintenance-free sealing system provided in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a maintenance-free sealing system provided in another embodiment of the present invention; Figure 3 For the turret and Figure 1 and Figure 2 A schematic diagram of the maintenance-free sealing system in the diagram; Figure 4 This is a schematic diagram of the constant pressure dynamic suppression system in the maintenance-free sealing system provided in an embodiment of the present invention; Figure 5 for Figure 3 A magnified view of a section at point A in the middle; Figure 6 for Figure 3 A magnified view of a section at point B in the middle; Figure 7 for Figure 2 A schematic diagram of the structure of the drive ring and the sealing assembly on the atmospheric side; Figure 8 for Figure 7 A sectional view; Figure 9 for Figure 2 A schematic diagram of the structure of the central spindle sleeve and the sealing assembly on the medium side; Figure 10 for Figure 9 A sectional view; Figure 11 This is a schematic diagram of the structure of the drive ring, main shaft sleeve, and sealing assembly on the medium side; Figure 12 for Figure 1 In the middle, a cross-sectional view of the overall structure of the main shaft sleeve, drive ring, and sealing assembly on the medium side, and dynamic sealing ring on the atmospheric side; In the diagram: 1-Body; 11-Medium side body; 12-Atmosphere side body; 2-Bearing; 3-Sealing assembly; 31-Static sealing ring; 32-Dynamic sealing ring; 33-Spring; 4-Main shaft sleeve; 41-Key; 42-Annular groove; 5-Sliding shaft sleeve; 6-Isolation ring; 7-Drive ring; 71-Fixing bolt; 81-Isolation fluid outlet; 82-Isolation fluid inlet; 100-Main shaft; 200-Turret housing; 91-Reservoir tank; 92-Pressure compensator; 93-Isolation fluid tank; 94-Make-up pump. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The following is combined with Figures 1 to 12 The following describes embodiments of the present invention.

[0025] This invention provides a maintenance-free sealing system, including a main shaft sleeve 4, a body 1, and two sealing assemblies 3. Each sealing assembly 3 includes a dynamic sealing ring 32 and a static sealing ring 31. The main shaft sleeve 4 is used to be sleeved and fixed on the main shaft 100, and the body 1 is used to be fixedly mounted on the turret housing 200. The dynamic sealing ring 32 is sleeved on the main shaft sleeve 4 at intervals along the axial direction and can rotate with the main shaft 100. One static sealing ring 31 corresponds to one dynamic sealing ring 32. The static sealing ring 31 is disposed on the body 1 and has the freedom to move along the axial direction. Under the action of a pre-set elastic force, the static sealing ring 31 fits with the end face of the dynamic sealing ring 32 to form a sealing pair. A sealing cavity is constructed between the two sealing assemblies 3, the main shaft sleeve 4, and the body 1. The sealing cavity is used to pre-fill the isolation fluid. The dynamic sealing ring 32 and the static sealing ring 31 are made of ceramic or hard alloy material. A sealing ring is provided between the main shaft sleeve 4 and the main shaft 100.

[0026] In this embodiment, both the dynamic sealing ring 32 and the static sealing ring 31 are made of ceramic or hard alloy materials. These materials possess extremely high hardness, compressive strength, and deformation resistance, enabling them to withstand higher medium pressures without irreversible deformation or damage. Furthermore, the static sealing ring 31 has axial freedom of movement and, under preload, tightly fits the end face of the dynamic ring, ensuring good tracking and contact of the sealing pair even during pressure fluctuations, preventing opening and leakage of the sealing interface due to increased pressure. Therefore, this invention is stably applicable to higher-pressure insulating medium environments (e.g., ≥0.8MPa), removing the limitations of traditional seals on increasing electrical transmission power and providing higher power transmission guarantees for single power generation equipment. Moreover, ceramics and hard alloys are naturally inert to salt spray corrosion and ultraviolet radiation, and their performance will not degrade due to these environmental factors, solving the fundamental defects of elastic materials such as easy aging, embrittlement, and cracking. Ceramic and cemented carbide have low coefficients of thermal expansion and good dimensional stability under alternating high and low temperature conditions. This avoids thermal deformation or cracking of the sealing surface due to excessive temperature difference, thus ensuring the reliability of the sealing performance.

[0027] In some embodiments, the present invention further includes a bearing 2, which provides rotational support for the main shaft 100; the bearing 2 is disposed inside or outside the sealed cavity; when the bearing 2 is disposed inside the sealed cavity, the bearing 2 is located between two sealing assemblies 3.

[0028] This embodiment includes two specific embodiments. The first is that the bearing 2 is disposed on the outside of the integral structure formed by the two sealing assemblies 3, and the second is that the bearing 2 is disposed between the two sealing assemblies 3.

[0029] In the second embodiment, the bearing 2 and two sets of sealing assemblies 3 are integrated into a single body 1, ensuring extremely high coaxiality and installation accuracy, fundamentally reducing uneven wear and abnormal wear caused by alignment errors. Therefore, the sealing system described in this invention has an extremely long service life in harsh marine environments, enabling "maintenance-free" operation with the same lifespan as the main equipment, completely avoiding the huge operating costs and production losses caused by frequent shutdowns for seal replacement. Furthermore, the integrated design ensures the concentricity of the bearing 2 and the seal; even with oscillation, the entire rotating assembly moves as a whole, with minimal internal relative displacement, protecting the delicate sealing interface. Therefore, the system described in this embodiment can better adapt to the uncertain directional oscillations during turret operation, exhibiting higher operational stability and reliability.

[0030] In some embodiments, the isolation fluid is lubricating oil.

[0031] In this embodiment, the lubricating oil flows in the gap between the sealed cavity and the bearing 2, which not only isolates the medium but also lubricates the bearing 2, simplifying the system structure (eliminating the need for a separate bearing lubrication system) and improving overall reliability.

[0032] In some embodiments, the present invention further includes a sliding bushing 5, with the bearing 2 disposed in the sealed cavity. The sliding bushing 5 is slidably fitted onto the outside of the main bushing 4 along the axial direction of the main bushing 4. The sliding bushing 5 is connected to the main bushing 4 via a key 41. The inner ring of the sliding bushing 5 and the bearing 2 are fixedly connected by an interference fit, and the outer ring of the body 1 and the bearing 2 are fixedly connected by an interference fit. The sliding bushing 5 and the inner ring of the bearing 2 form a rotating assembly. The rotating assembly can slide axially on the main bushing 4 to compensate for the thermal expansion and contraction caused by temperature changes between the main bushing 4 and the rotating assembly. At least one dynamic sealing ring 32 in the sealing assembly 3 has a force transmission structure with the rotating assembly, and its installation method allows it to undergo axial displacement to adapt to deformation when subjected to the axial thrust generated by the thermal expansion of the rotating assembly.

[0033] In this embodiment, the rotating assembly consisting of the sliding bushing 5 and the inner ring of the bearing can slide axially on the main bushing 4, directly compensating for the macroscopic dimensional changes (typically on the order of 0.2-0.8 mm) caused by the difference in the coefficients of thermal expansion of the materials between the main shaft 100, the main bushing 4, and the rotating assembly, effectively avoiding the risk of structural jamming or loss of clearance in the bearing 2. Furthermore, through a force transmission structure (such as the drive ring 7 in the following embodiment), the axial stress on the rotating assembly is transmitted to the dynamic sealing ring 32, allowing it to undergo micron-level elastic displacement. This ensures that under extreme temperature shocks, the end face pressure of the sealing pair remains within the optimal range, avoiding abnormal wear caused by excessive pressure on the sealing surface or leakage due to separation.

[0034] In some embodiments, a constant-pressure dynamic suppression system is also included, which provides and maintains a pressure of isolation fluid above that of the sealed medium in the sealed cavity.

[0035] In this embodiment, the constant pressure dynamic suppression system continuously injects a pressure-higher-than-the-pressure insulating fluid (such as lubricating oil) into the sealed cavity, forming a stable "pressure wall" on the inner side of the dynamic and static ring sealing pair. This ensures that the sealed medium (insulating medium) is subjected to a net pressure difference pointing inwards under any operating condition, fundamentally eliminating the possibility of media leakage and achieving active suppression rather than passive sealing. Furthermore, the sealing pair will experience normal wear during long-term operation, resulting in a slight decrease in preload. The constant pressure dynamic suppression system can monitor and maintain a constant pressure within the sealed cavity in real time, effectively and automatically compensating for the potential decrease in sealing force due to wear, ensuring stable sealing performance throughout its entire lifespan. This is key to achieving "maintenance-free" operation.

[0036] In some alternative embodiments, oil can also be added manually, i.e., by detecting the pressure of the fluid in the sealed cavity in real time, and when it is less than a set threshold, oil can be added manually.

[0037] In some embodiments, the bearing 2 is disposed in the sealed cavity, and two sealing assemblies 3 are arranged one above the other, with an isolation ring 6 provided between the upper sealing assembly 3 and the bearing 2.

[0038] In this embodiment of the invention, the isolation ring 6 forms a physical barrier between the upper sealing assembly 3 and the bearing 2. It can effectively intercept and collect trace amounts of metal or ceramic wear debris generated by the normal wear of the moving and stationary ring friction pair of the upper sealing assembly 3, preventing these hard and sharp particles from entering the bearing 2 cavity downwards, thereby greatly extending the service life of the bearing 2 and ensuring operational accuracy and reliability.

[0039] Furthermore, wear debris will gradually accumulate within the cavity formed by the isolation ring 6. The health status and wear rate of the sealing pair can be indirectly assessed by inspecting or analyzing the content and morphology of the wear debris at this location during maintenance cycles, thus achieving condition monitoring.

[0040] In some embodiments, the pre-set elastic force comes from a spring 33 built into the body 1. Under normal conditions, the spring 33 is in a compressed state and one end abuts against the side of the static sealing ring 31 away from the dynamic sealing ring 32.

[0041] Multiple springs 33 are provided, and all of them are positioned on the main body 1.

[0042] In some embodiments, the end of the main shaft sleeve 4 closest to the medium is integrally constructed with an annular groove 42 facing the static sealing ring 31, and one of the dynamic sealing rings 32 is disposed in the annular groove 42. A sealing ring is disposed between the wall of the annular groove 42 and the wall of the dynamic sealing ring 32. The end of the main shaft sleeve 4 closest to the outside atmosphere is fitted with a drive ring 7. The main shaft sleeve 4 and the drive ring 7 are connected to the main shaft 100 by bolts. One end of the drive ring 7 abuts against the end of the sliding shaft sleeve 5. A limiting part is constructed on the drive ring 7. Another dynamic sealing ring 32 is fitted on the drive ring 7 and its axial movement away from the static sealing ring 31 is restricted by the limiting part.

[0043] In this embodiment, the complex positioning and fixing functions of the dynamic sealing ring 32 near the medium are integrated into a single machined part. The dynamic sealing ring 32 can be precisely positioned simply by embedding it into the annular groove 42, greatly simplifying the assembly process and reducing reliance on operator skills. Simultaneously, the integrated design avoids the poor sealing problems that may result from using multiple separate fasteners (such as screws). Furthermore, this embodiment allows for positioning on one side of the system, with one end of the drive ring 7 abutting against the end of the sliding sleeve 5. When the sliding sleeve 5 generates axial thrust due to thermal expansion, this thrust acts directly on the drive ring 7 through the abutment surface. Since the drive ring 7 is fixed to the main shaft 100 by bolts, this connection pair allows for micron-level elastic deformation or slight slippage under enormous thrust. The bearing 2 also drives the body 1 and the static sealing ring 31 to slide axially, thereby enabling the dynamic sealing ring 32 and the static sealing ring 31 to slide synchronously, avoiding abnormal pressure between the two components caused by slippage of only one component within the sealing pair.

[0044] In some examples, when the dynamic sealing ring 32 on the atmospheric side is located above the static sealing ring 31, the limiting part is a fixing bolt 71 for fixing the drive ring 7. Specifically, the drive ring 7 is fixed to the main sleeve 4 and the main shaft 100 by a plurality of fixing bolts 71 arranged sequentially along the axial direction. Some of the fixing bolts 71 protrude from the outer wall of the drive ring 7. The upper edge of the dynamic sealing ring 32 is provided with a groove, and the fixing bolts 71 are located in the groove, thereby achieving the purpose of restricting the upward movement of the dynamic sealing ring 32.

[0045] In some examples, when the dynamic sealing ring 32 on the atmospheric side is located below the static sealing ring 31, a groove for accommodating the dynamic sealing ring 32 is provided on the drive ring 7, and the bottom surface of the groove is the limiting part.

[0046] In some examples, when the dynamic sealing ring 32 on the medium side is located above the static sealing ring 31, it is necessary to restrict the downward movement of the dynamic sealing ring 32 on the medium side. In this example, an annular groove coaxially with the main shaft sleeve 4 is opened on the outer wall below the dynamic sealing ring 32, and an arc-shaped limiting plate is engaged in the annular groove. The upper surface of the arc-shaped limiting plate abuts against the lower surface of the dynamic sealing ring 32, thereby achieving the purpose of restricting the downward and upward movement of the dynamic sealing ring 32.

[0047] In some examples, the static sealing ring 31 is achieved by cooperating with a pin set on the body 1: the static sealing ring 31 and the body 1 are relatively fixed in circumferential position and can slide relative to each other in axial direction; the dynamic sealing ring 32 is achieved by cooperating with a pin set on the drive ring 7 or the main shaft sleeve 4: the dynamic sealing ring 32 and the drive ring 7 or the main shaft sleeve 4 are relatively fixed in circumferential position and can slide relative to each other in axial direction.

[0048] In some embodiments, the constant pressure dynamic suppression system includes a storage tank 91, a pressure compensator 92, a replenishment pump 94, an isolation fluid tank 93, monitoring instruments, and a control system; the outlet of the storage tank 91 is connected to the isolation fluid inlet 82 of the sealed cavity via a supply pipeline; the pressure compensator 92 is connected to the storage tank 91 or the supply pipeline for pre-pressurizing and maintaining the stability of the system's base pressure; the inlet of the replenishment pump 94 is connected to the isolation fluid tank 93, and its outlet is connected to the storage tank 91; the monitoring instruments include a pressure transmitter, a temperature sensor, and a level sensor; the pressure transmitter is installed on the supply pipeline and / or the storage tank 91 for real-time detection of the isolation fluid pressure; the temperature sensor's temperature detection end is connected to the isolation fluid outlet 82 of the sealed cavity. A connection is established for real-time detection of the temperature of the isolation fluid within the sealed cavity; a level sensor is installed inside the isolation fluid tank 93 for real-time monitoring of the isolation fluid level; the control system is connected to a pressure transmitter, a temperature sensor, a level sensor, and a replenishment pump 94; the control system is configured to: receive signals from the monitoring instruments and control the operation of the replenishment pump 94 accordingly; when the pressure value detected by the pressure transmitter is lower than the first pressure set value, the replenishment pump 94 is started to draw isolation fluid from the isolation fluid tank 93 and pump it into the storage tank 91; when the pressure value reaches a second pressure set value higher than the first pressure set value, the replenishment pump 94 is stopped; when the level sensor detects that the liquid level is lower or higher than the set range, the control system issues an alarm signal.

[0049] In this embodiment, a closed-loop control circuit consisting of real-time monitoring by a pressure transmitter, intelligent decision-making by the control system, and precise execution by the replenishment pump 94 enables the system to maintain the pressure of the isolation fluid in the sealing cavity at a stable margin (e.g., 0.15 MPa) higher than the pressure of the sealed medium, regardless of changes in operating conditions and normal wear. This proactively establishes and maintains an insurmountable pressure barrier, fundamentally preventing leakage of the sealed medium. Furthermore, this embodiment incorporates a two-stage pressure maintenance mechanism. Minor daily pressure fluctuations are absorbed and compensated instantaneously and without power consumption by the pressure compensator 92 (e.g., an accumulator); only when the leakage is significant, causing the pressure to continuously drop to the first set value, is the replenishment pump 94 activated for energy-intensive pressure replenishment. This design significantly reduces the number of starts and stops of the replenishment pump 94, saving energy and extending the pump's lifespan.

[0050] In some embodiments, the body 1 includes a medium-side body 11 and an atmospheric-side body 12. After the two phases are stacked, they are fixed to the turret housing 200 by the same set of bolts. Sealing rings are provided between the contact surfaces of the medium-side body 11 and the turret housing 200, and between the contact surfaces of the medium-side body 11 and the atmospheric-side body 12.

[0051] The present invention also provides an electrical transmission device for a single-point mooring system, comprising a turret housing 200, a main shaft 100, and a maintenance-free sealing system as described above. The turret housing 200 is filled with a sealing medium, which is an insulating medium. The turret housing 200 has a mounting opening extending along its thickness direction, through which the main shaft 100 passes. The maintenance-free sealing system is fitted onto the main shaft 100 located at the mounting opening to seal the mounting opening.

[0052] Specifically, such as Figure 4 As shown, the turret housing 200 is used for electrical transmission. This specification focuses on the sealing structure between the spindle 100 and the turret housing 200; therefore, the electrical transmission structure within the turret is not shown in the figure. In this embodiment, since both the upper and lower parts of the turret housing 200 need to be sealed, the structures of the two sealing parts are largely the same. The main difference is that the upper and lower structures are reversed. This is because the positions of the medium side and the atmospheric side are reversed. To adapt to the positions of the medium side and the atmospheric side, the structure of the sealing part is also reversed accordingly. In addition, some detailed structures have been modified to conform to the reversed structure. See details below. Figure 5 and Figure 6 The structure shown.

[0053] This embodiment possesses all the advantages of the above embodiments, and will not be repeated here.

[0054] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A maintenance-free sealing system, characterized in that: The system includes a main shaft sleeve, a body, and two sealing assemblies. Each sealing assembly includes a dynamic sealing ring and a static sealing ring. The main shaft sleeve is fitted and fixed onto the main shaft, and the body is fixedly mounted on the turret housing. The dynamic sealing rings are fitted onto the main shaft sleeve at intervals along its axial direction and can rotate with the main shaft. One static sealing ring corresponds to one dynamic sealing ring. The static sealing ring is mounted on the body and has the freedom to move along its axial direction. Under the action of a pre-set elastic force, the static sealing ring fits against the end face of the dynamic sealing ring to form a sealing pair. A sealing cavity is constructed between the two sealing assemblies, the main shaft sleeve, and the body. The sealing cavity is used to pre-fill a separating fluid. The dynamic and static sealing rings are made of ceramic or hard alloy materials.

2. The maintenance-free sealing system according to claim 1, characterized in that: It also includes a bearing for providing rotational support for the spindle; the bearing is disposed within or outside the sealed cavity; when the bearing is disposed within the sealed cavity, the bearing is located between the two sealed assemblies.

3. The maintenance-free sealing system according to claim 2, characterized in that: It also includes a sliding bushing, the bearing being disposed within the sealed cavity, the sliding bushing being slidably fitted onto the outside of the main bushing along the axial direction, the sliding bushing being connected to the main bushing via a key; the sliding bushing and the inner ring of the bearing are fixedly connected by an interference fit, the body and the outer ring of the bearing are fixedly connected by an interference fit, the sliding bushing and the inner ring of the bearing form a rotating assembly, the rotating assembly being able to slide axially on the main bushing to compensate for the thermal expansion and contraction caused by temperature changes between the main bushing and the rotating assembly, at least one of the dynamic sealing rings in the sealing assembly having a force transmission structure with the rotating assembly and its installation method allowing it to undergo axial displacement to adapt to deformation when subjected to the axial thrust generated by the thermal expansion of the rotating assembly.

4. The maintenance-free sealing system according to claim 2, characterized in that: It also includes a constant pressure dynamic suppression system, which is used to supply and maintain a pressure of isolation fluid higher than that of the sealed medium to the sealed cavity.

5. The maintenance-free sealing system according to claim 2, characterized in that: The bearing is disposed in the sealed cavity, and the two sealing assemblies are arranged one above the other, with an isolation ring between the upper sealing assembly and the bearing.

6. The maintenance-free sealing system according to claim 3, characterized in that: The isolation fluid is lubricating oil.

7. The maintenance-free sealing system according to claim 3, characterized in that: The pre-set elastic force comes from a spring built into the body. Under normal conditions, the spring is in a compressed state and one end abuts against the side of the static sealing ring away from the dynamic sealing ring.

8. The maintenance-free sealing system according to claim 6, characterized in that: The end of the main shaft sleeve closest to the medium has an integrally formed annular groove facing the static sealing ring. One of the dynamic sealing rings is disposed in the annular groove, and a sealing ring is provided between the wall of the annular groove and the wall of the dynamic sealing ring. The end of the main shaft sleeve closest to the outside atmosphere is fitted with a drive ring. The main shaft sleeve and the drive ring are connected to the main shaft by bolts. One end of the drive ring abuts against the end of the sliding shaft sleeve. A limiting part is constructed on the drive ring, and the other dynamic sealing ring is fitted on the drive ring and its axial movement away from the static sealing ring is restricted by the limiting part.

9. The maintenance-free sealing system according to claim 4, characterized in that: The constant pressure dynamic suppression system includes a storage tank, a pressure compensator, a replenishment pump, an isolation fluid tank, monitoring instruments, and a control system. The outlet of the storage tank is connected to the isolation fluid inlet of the sealed cavity via a supply pipeline. The pressure compensator is connected to the storage tank or the supply pipeline for pre-pressurization and maintaining the stability of the system's base pressure. The inlet of the replenishment pump is connected to the isolation fluid tank, and its outlet is connected to the storage tank. The monitoring instruments include a pressure transmitter, a temperature sensor, and a level sensor. The pressure transmitter is installed on the supply pipeline and / or the storage tank for real-time detection of the isolation fluid pressure. The temperature sensor's temperature detection end is connected to the isolation fluid outlet of the sealed cavity for real-time detection... The system measures the temperature of the isolation fluid within the sealed cavity; a level sensor is installed inside the isolation fluid tank to monitor the liquid level of the isolation fluid in real time; the control system is signal-connected to the pressure transmitter, temperature sensor, level sensor, and replenishment pump; the control system is configured to: receive signals from the monitoring instruments and control the operation of the replenishment pump accordingly; when the pressure value detected by the pressure transmitter is lower than a first pressure setpoint, control the replenishment pump to start and pump isolation fluid from the isolation fluid tank into the storage tank; when the pressure value reaches a second pressure setpoint higher than the first pressure setpoint, control the replenishment pump to stop; when the level sensor detects that the liquid level is lower or higher than a set range, the control system issues an alarm signal.

10. An electrical transmission device for a single-point mooring system, characterized in that, The invention includes a turret housing, a main shaft, and a maintenance-free sealing system as described in any one of claims 1-9. The turret housing is filled with a sealing medium, which is an insulating medium. The turret housing has a mounting opening that extends through its thickness, and the main shaft passes through the mounting opening. The maintenance-free sealing system is fitted onto the main shaft located at the mounting opening and is used to seal the mounting opening.

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