An isobaric seal and pressure balance structure for a deep sea pump

Abstract

The application discloses an isobaric sealing and pressure balancing structure for a deep-sea pump, wherein the isobaric sealing structure takes the seawater pressure itself as a control signal source, realizes the self-dynamic balance of the pressure inside and outside the bearing cavity through the mechanical pressure following of a pressure correction elastic film, the oil feeding layout of a shaft center and a multifunctional integrated pressure boosting valve, and does not need external energy supply, and the self-adaptation is strong and the integration degree is high, so that the problems of sealing failure and lubrication shortage of a bearing body of the deep-sea pump caused by a huge pressure difference are effectively solved, and meanwhile, the axial force balancing device of the high-efficiency impeller upper cover plate pressure balancing structure and the impeller lower cover plate pressure balancing structure offsets the axial load generated by the impeller, and the risk of bearing overheating and burning and pump shaft fracture is avoided.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery technology, specifically to a deep-sea pump, and more specifically to an isobaric sealing and pressure balancing structure for a deep-sea pump. Background Technology

[0002] Deep-sea pumps operate in extreme environments thousands of meters below the surface, facing multiple challenges such as high pressure, seawater corrosion, and low lubricity. Their reliability hinges on effectively addressing two major issues: bearing housing pressure balance and impeller axial force balance. Failure in either can trigger a chain reaction of damage. The bearing housing is filled with lubricating oil and subjected to deep-sea pressures of tens of megapascals. Without pressure compensation, the enormous pressure difference can, at best, force lubricating oil to leak along the shaft seal, causing the bearing to burn out due to high temperatures from dry friction; at worst, it can deform and crush the casing, or allow high-pressure seawater to intrude. The corrosiveness and suspended sediment of seawater can rapidly damage precision components, even causing short circuits in the motor and rendering the entire pump unusable. The impeller, due to uneven pressure distribution between the front and rear cover plates, generates an axial force pointing towards the inlet. In multi-stage pumps, this force can reach tens of tons; without balancing, it can directly damage the bearing, causing overheating and burnout. In severe cases, the axial force can also tear the shaft seal, break the pump shaft, and cause a catastrophic accident involving rotor-stator collision. Pressure balance and axial force balance are the dual safeguards ensuring the reliable operation of deep-sea pumps. The former isolates seawater through a compensation device to maintain lubrication; the latter relies on structures such as a balance disc to offset axial loads. Without effective measures, even minor imbalances can be amplified dramatically under high pressure, causing irreparable damage. Therefore, there is an urgent need for an improved deep-sea pump structure.

[0003] This invention addresses the core problems of deep-sea pumps, such as the easy failure of bearing seals and the difficulty in balancing impeller axial forces under high pressure, corrosive, and low-lubrication environments. It employs a hydraulically optimized design based on the overall pump structure. Through an innovative isobaric sealing structure, the significant pressure difference between the inside and outside of the bearing body is effectively eliminated, preventing lubricant leakage and seawater intrusion, ensuring stable bearing lubrication. Simultaneously, a highly efficient axial force balancing device counteracts the tens of tons of axial load generated by the impeller, avoiding the risk of bearing overheating and burnout, and pump shaft breakage. This structure significantly improves the sealing reliability, operational stability, and service life of deep-sea pumps under extreme operating conditions, reduces maintenance costs, and optimizes the overall system performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and to propose an isobaric sealing and pressure balancing structure for deep-sea pumps.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An isobaric sealing and pressure balancing structure for a deep-sea pump includes an inlet section, a motor stator, a motor rotor, an impeller, an outlet section, a shaft, bearings, an outlet section sealing ring, a rotor sealing ring, a bearing cover, a shaft sleeve, a mechanical seal, a spring washer, and a key. The inlet section, impeller, and outlet section are arranged sequentially along the fluid flow direction. An impeller is fixedly mounted on one end of the shaft via a key, and the outlet section is mounted on the other end via a bearing. A bearing cover is located at the inlet end of the outlet section to fix the bearing, and the inner ring of the bearing cover is fixedly mounted on the shaft via a shaft sleeve and a mechanical seal. One end of the shaft sleeve abuts against the bearing, and the other end is secured by a spring washer. The impeller is abutted; a water outlet section sealing ring and a rotor sealing ring are provided between the motor rotor and the water outlet section; the motor rotor is fixedly installed on the outside of the impeller upper cover plate, and the motor stator is located on the radial outside of the motor rotor and its axial ends are fixedly connected to the water inlet section and the water outlet section respectively; the feature is that it also includes an equal pressure sealing structure, an impeller upper cover plate pressure balancing structure, and an impeller lower cover plate pressure balancing structure; the equal pressure sealing structure uses the pressure balancing principle to make the pressure inside the bearing structure consistent with the seawater pressure; the impeller upper cover plate pressure balancing structure and the impeller lower cover plate pressure balancing structure are efficiently linked to achieve dynamic pressure balance of the impeller.

[0007] Furthermore, the isobaric sealing structure includes a pressurizable oil tank, an oil inlet pipe, a pressure correction body, an inlet one-way pressure boosting valve, a return one-way valve, and a return oil pipe; an oil inlet channel is provided at the shaft center, and the oil inlet channel is connected to the bearing chamber through an oil inlet hole; the water outlet section includes a spatial guide vane inner cover plate, the spatial guide vane inner cover plate, the bearing, the bearing cover, and the shaft sleeve to form the aforementioned bearing chamber, and a return oil hole is provided at the outlet end of the spatial guide vane inner cover plate; the return oil hole is connected to the pressurizable oil tank through a return oil pipe and a return one-way valve.

[0008] Furthermore, the pressure correction body includes a pressure correction shell, a pressure correction elastic membrane, and a connecting hole. The pressure correction shell surrounds the outside of the pressure correction elastic membrane and its surface is uniformly provided with through connecting holes. The connecting holes are connected to seawater during pressure correction, and the pressure correction elastic membrane is connected to the oil inlet pipe.

[0009] Furthermore, the diameter of the connecting hole gradually decreases from the radially outer side to the radially inner side.

[0010] Furthermore, the liquid inlet one-way pressure boosting valve includes a valve body, a valve core, a valve ball, a valve body spring, and a valve outlet seat. The valve core is installed inside the valve body, and the valve ball, valve body spring, and valve outlet seat are arranged sequentially inside the valve core. Multiple three-dimensional twisted forward-tilting blades are arranged on the outer circumference of the valve outlet seat. A gradually narrowing pressure boosting hole is arranged at the axis of the valve outlet seat, and a through jet hole inclined towards the axis is arranged inside the valve outlet seat body.

[0011] Furthermore, the impeller includes an upper impeller cover plate, inlet blades, and a lower impeller cover plate. The outlet section also includes a spatial guide vane outer cover plate. The pressure balancing structure of the upper impeller cover plate is located in the cavity enclosed by the spatial guide vane outer cover plate, the motor rotor, and the upper impeller cover plate. It includes a balancing body disposed in the cavity and a first upper cover plate balancing ring, a first upper cover plate water outlet hole, a second upper cover plate balancing ring, and a second upper cover plate water outlet hole arranged sequentially at the outlet end of the upper impeller cover plate. The side of the balancing body near the impeller is provided with two auxiliary balancing rings that cooperate with the first upper cover plate balancing ring and the second upper cover plate balancing ring, respectively. There is an axial clearance between the two auxiliary balancing rings and the first upper cover plate balancing ring and the second upper cover plate balancing ring. The cavity between the balancing body and the upper impeller cover plate is divided into a first balancing cavity that is axially closer to the motor rotor and a second balancing cavity that is farther away from the motor rotor. The first upper cover plate water outlet hole is in fluid communication with the first balancing cavity, and the second upper cover plate water outlet hole is in fluid communication with the second balancing cavity.

[0012] Furthermore, the diameter of the water outlet hole of the first upper cover plate is greater than the diameter of the water outlet hole of the second upper cover plate.

[0013] Furthermore, a back guide plate that mates with the motor rotor slot is provided on the side of the balancing body away from the impeller to achieve auxiliary balancing and circulation guidance.

[0014] Furthermore, a first balance spring is provided between the side of the balance body away from the impeller and the motor rotor, and a second balance spring is provided between the balance body and the outer cover plate of the space guide vane.

[0015] Furthermore, the spring constant of the first balance spring is smaller than that of the second balance spring.

[0016] Furthermore, the pressure balancing structure of the impeller lower cover plate is located in the cavity enclosed by the inner cover plate of the space guide vane and the lower cover plate of the impeller. It includes an axial cylinder and a planar annulus disposed on the inner side wall of the inner cover plate of the space guide vane. The axial cylinder and the planar annulus are fixedly connected at one end and form a triangular balancing chamber with the inner cover plate of the space guide vane. The side of the axial cylinder near the inner cover plate of the space guide vane is fixedly connected to the inner cover plate of the space guide vane through a third balancing spring away from the planar annulus and a fourth balancing spring near the planar annulus.

[0017] Furthermore, the spring constant of the third balance spring is greater than that of the fourth balance spring.

[0018] Furthermore, the planar annular body is provided with an axially penetrating flow hole, and the inner cover plate of the spatial guide vane is provided with a swirling hole that penetrates and communicates with the triangular-like balance chamber. The swirling direction of the swirling hole is consistent with the swirling direction of the spatial guide vane.

[0019] Furthermore, centrifugal blades are provided on the side of the impeller lower cover plate near the triangular balance chamber, and the centrifugal blades correspond to the planar annular body.

[0020] Furthermore, a concave wear-resistant ring is provided at the outlet end of the impeller lower cover plate, and a convex wear-resistant ring is provided at the inlet end of the space guide vane inner cover plate. The two form a concave-convex fit to achieve the balance of liquid backflow in the triangular balance chamber.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The isobaric sealing structure of this invention comprises a pressurizable oil tank, an oil inlet pipe, a pressure correction body, an inlet one-way pressure boosting valve, a return one-way valve, and a return oil pipe, forming a closed-loop oil circuit system. An oil inlet channel is located at the pump shaft center, connecting to a bearing chamber formed by a spatial guide vane inner cover plate, bearing, bearing cap, and shaft sleeve via an oil inlet hole. A return oil hole is located at the outlet end of the spatial guide vane inner cover plate, connecting to the pressurizable oil tank via a return oil pipe and a return one-way valve. This layout forms a directional circulation path of "oil inlet at the shaft center → lubrication in the chamber → oil return from the cover plate," ensuring that lubricating oil preferentially reaches the bearing friction pair, effectively improving lubrication and cooling efficiency.

[0023] The pressure correction unit consists of a pressure correction shell, a pressure correction elastic diaphragm, and connecting holes evenly distributed on the shell surface. The diameter of the connecting holes gradually decreases from the radially outer side to the radially inner side. During pressure correction, the holes are connected to seawater. The pressure correction elastic diaphragm is connected to the oil inlet pipe. This structure uses the elastic diaphragm as a pressure sensing element to transmit seawater pressure to the bearing chamber through the oil inlet pipe. This enables the bearing chamber oil pressure to follow the deep-sea environment pressure in real time, passively, and without external control devices, eliminating the huge pressure difference between the inside and outside, and preventing lubricating oil leakage and seawater intrusion.

[0024] The inlet one-way pressure boosting valve integrates a valve housing, valve core, valve ball, valve body spring, and valve outlet seat. Multiple three-dimensional twisted forward-inclined blades are located on the outer circumference of the outlet seat to guide and accelerate flow. A tapered pressure boosting orifice is located at the axis to achieve localized pressure boosting. A through-jet orifice inclined towards the axis is located within the seat to achieve directional and enhanced pressure boosting. This valve integrates four functions—one-way check valve, flow guidance, pressure boosting, and jet injection—into a single component. It ensures unidirectional oil flow while achieving localized pressure boosting and precise lubrication of bearing components, significantly enhancing the sealing reliability and operational stability of the system under extreme deep-sea conditions.

[0025] 2. The impeller upper cover pressure balancing structure of the present invention is disposed within a cavity enclosed by a spatial guide vane outer cover plate, a motor rotor, and an impeller upper cover plate. It mainly includes a balancing body and a first upper cover plate balancing ring, a first upper cover plate water outlet, a second upper cover plate balancing ring, and a second upper cover plate water outlet, sequentially disposed at the outlet end of the impeller upper cover plate. Two auxiliary balancing rings are disposed on the side of the balancing body near the impeller, respectively cooperating with the first and second upper cover plate balancing rings, with axial clearance maintained between the two sets of balancing rings. The cavity between the balancing body and the impeller upper cover plate is divided into a first balancing cavity near the motor rotor and a second balancing cavity away from the motor rotor. The first upper cover plate water outlet is in fluid communication with the first balancing cavity, and the second upper cover plate water outlet is in fluid communication with the second balancing cavity. This structure establishes a graded pressure regulation mechanism at the impeller upper cover plate through the cooperation of the two balancing rings and the two balancing cavities.

[0026] This invention utilizes a differentiated orifice design between the first and second upper cover plate outlet holes—the first outlet hole diameter is larger than the second—to create a controllable pressure difference between the media in the two balancing chambers. This generates a balancing force on the balancing body that is opposite to the axial force of the impeller. When the high-pressure medium at the impeller's upper cover plate enters the corresponding balancing chamber through outlet holes of different diameters, the pressure in the two chambers is adjusted to different levels due to the different outflow capacities. This pressure difference acts on the balancing body and its auxiliary balancing ring, generating a reverse axial thrust, thus achieving adaptive cancellation of the enormous axial force on the impeller. This structure requires no external power source, relying entirely on the pump's own hydraulic parameters to achieve graded balancing and precise control of the axial force.

[0027] A back guide plate, matching the motor rotor slot, is installed on the side of the balancing body away from the impeller. This utilizes the hydrodynamic pressure effect generated by the rotor rotation to achieve auxiliary balancing and circulation guidance, further enhancing balance stability. Simultaneously, a first balancing spring is installed between the balancing body and the motor rotor, and a second balancing spring is installed between the balancing body and the outer cover plate of the spatial guide vane. The stiffness coefficient of the first balancing spring is smaller than that of the second. This differentiated dual-spring design allows the balancing body to adaptively adjust the balancing gap with minute axial displacements when axial force fluctuates, resulting in excellent dynamic response performance. In extreme operating conditions or sudden pressure changes, the second balancing spring, with its larger stiffness coefficient, acts as a rigid limiter, preventing excessive displacement of the balancing body that could lead to collisions or jamming, ensuring structural safety. The two work together to achieve a balance between flexible adaptive adjustment and rigid safety limiting. Furthermore, the recirculation structure also enables efficient cooling of the motor rotor.

[0028] 3. The impeller lower cover pressure balancing structure of this invention is disposed within a cavity enclosed by the inner cover plate of the spatial guide vane and the impeller lower cover plate. It mainly includes an axial cylinder and a planar annulus fixedly connected to the inner wall of the inner cover plate of the spatial guide vane. The two are fixedly connected at one end and, together with the inner cover plate of the spatial guide vane, form a triangular-like balancing chamber. The side of the axial cylinder near the inner cover plate of the spatial guide vane is fixedly connected to the inner cover plate of the spatial guide vane via a third balancing spring away from the planar annulus and a fourth balancing spring near the planar annulus, with the stiffness coefficient of the third balancing spring being greater than that of the fourth balancing spring. This differentiated spring design causes the axial cylinder and the planar annulus to deflect or tilt when subjected to axial force, thereby adaptively adjusting the volume and pressure of the triangular-like balancing chamber to achieve a dynamic balance response.

[0029] This invention features a swirling orifice connected to a triangular-shaped balance chamber within the inner cover plate of a spatial guide vane. The swirling orifice rotates in the same direction as the guide vane, allowing the high-pressure medium from the guide vane outlet to enter the balance chamber in the same swirling direction as the mainstream. The centrifugal effect of the swirling flow establishes a pressure gradient within the chamber. Simultaneously, an axially penetrating flow hole is provided on the planar annular body, and centrifugal blades corresponding to the planar annular body are positioned on the lower cover plate of the impeller near the triangular-shaped balance chamber. As the impeller rotates, the centrifugal blades exert centrifugal pressure on the liquid within the chamber, guiding the fluid to circulate and exit. This, combined with the swirling pressure introduced by the swirling orifice, creates a reverse axial thrust, effectively counteracting part of the axial force in the direction of the lower cover plate. The flow hole also serves as a throttling and pressure-relief channel, regulating the pressure level within the chamber and preventing excessive pressure from causing balance failure.

[0030] This invention features a concave wear-resistant ring at the outlet end of the impeller's lower cover plate and a convex wear-resistant ring at the inlet end of the inner cover plate of the spatial guide vane, forming a concave-convex axial sealing structure. This concave-convex wear-resistant ring fit not only serves as a balanced sealing interface for liquid backflow within the triangular-shaped balance chamber, effectively controlling leakage of high-pressure liquid into the low-pressure area and ensuring the pressure-building capacity of the balance chamber, but also extends the leakage path by utilizing the tortuous gap formed by the concave-convex fit, further reducing the leakage amount. Furthermore, the wear-resistant rings are made of a hard, wear-resistant material, significantly improving the structure's wear resistance in deep-sea sandy environments and extending the service life of the balance structure. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0032] Figure 1This is a schematic diagram of an isobaric sealing and pressure balancing structure for a deep-sea pump according to the present invention.

[0033] Figure 2 for Figure 1 Schematic diagram of the structure of the inlet liquid one-way pressure booster valve;

[0034] Figure 3 for Figure 1 A schematic diagram of the improved pressure balance structure of the impeller upper cover plate in region A of the middle section;

[0035] Figure 4 for Figure 1 A schematic diagram of the improved pressure balance structure of the impeller lower cover plate in section B of the diagram.

[0036] The reference numerals in the above figures are as follows: 1. Inlet section; 2. Motor stator; 3. Motor rotor; 4. Impeller; 5. Outlet section; 6. Shaft; 7. Bearing; 8. Outlet section sealing ring; 9. Rotor sealing ring; 10. Bearing gland; 11. Shaft sleeve; 12. Mechanical seal; 13. Spring washer; 14. Key; 15. Isobaric sealing structure; 16. Impeller upper cover pressure balance structure; 17. Impeller lower cover pressure balance structure; 18. Pressurizable oil tank; 19. Oil inlet pipe; 10. Pressure correction body; 11. Liquid inlet one-way pressure boosting valve; 12. Liquid return one-way valve; 13. Oil return pipe; 14. Oil return channel; 15. Oil inlet hole; 15. Inner cover plate of spatial guide vane; 15. Outer cover plate of spatial guide vane; 15. Oil return hole; 16. Pressure correction housing; 17. Pressure correction elastic diaphragm; 18. Connecting hole; 19. Valve housing; 10. 541, Valve inner core 1542, Valve ball 1543, Valve body spring 1544, Valve outlet seat 1545, Three-dimensional twisted forward-inclined blade 15451, Jet hole 15452, Pressure boosting hole 15453, Impeller upper cover plate 41, Inlet blade 42, Impeller lower cover plate 43, First upper cover plate balance ring 1611, First upper cover plate water outlet hole 1612, Second upper cover plate balance ring 1613, Second upper cover plate water outlet hole 1614, Balance body 1615, First balance spring 1616, Second balance spring 1617, Axial cylinder 171, Planar ring 172, Third balance spring 173, Fourth balance spring 174, Flow hole 175, Swirl hole 176, Centrifugal blade 177, Concave wear-resistant ring 178, Convex wear-resistant ring 179. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0038] The present invention will now be described in further detail with reference to the accompanying drawings.

[0039] like Figure 1-4 As shown, an isobaric sealing and pressure balancing structure for a deep-sea pump includes an inlet section 1, a motor stator 2, a motor rotor 3, an impeller 4, an outlet section 5, a shaft 6, a bearing 7, an outlet section sealing ring 8, a rotor sealing ring 9, a bearing cover 10, a shaft sleeve 11, a mechanical seal 12, a spring washer 13, and a key 14. The inlet section 1, impeller 4, and outlet section 5 are arranged sequentially along the fluid flow direction. One end of the shaft 6 is fixedly mounted with the impeller 4 via the key 14, and the other end is mounted with the outlet section 5 via the bearing 7. The bearing cover 10 is located at the inlet end of the outlet section 5 to fix the bearing 7. The inner ring of the bearing cover 10 is fixedly mounted on the shaft 6 via the shaft sleeve 11 and the mechanical seal 12. One end of the shaft sleeve 11 abuts against the bearing 7. The other end abuts against the impeller 4 via a spring washer 13; an outlet section sealing ring 8 and a rotor sealing ring 9 are provided between the motor rotor 3 and the outlet section 5; the motor rotor 3 is fixedly installed on the outside of the upper cover plate of the impeller 4, and the motor stator 2 is located radially outside the motor rotor 3 and its two axial ends are fixedly connected to the inlet section 1 and the outlet section 5 respectively; the feature is that it also includes an equal pressure sealing structure 15, an impeller upper cover plate pressure balancing structure 16, and an impeller lower cover plate pressure balancing structure 17; the equal pressure sealing structure 15 uses the pressure balancing principle to make the pressure inside the bearing structure consistent with the seawater pressure; the impeller upper cover plate pressure balancing structure 16 and the impeller lower cover plate pressure balancing structure 17 are linked efficiently to achieve dynamic pressure balance of the impeller.

[0040] Furthermore, the isobaric sealing structure 15 includes a pressurizable oil tank 151, an oil inlet pipe 152, a pressure correction body 153, an inlet one-way pressure boosting valve 154, a return one-way valve 155, and an oil return pipe 156; an oil inlet channel 61 is provided at the shaft center of the shaft 6, and the oil inlet channel 61 is connected to the bearing 7 chamber through an oil inlet hole 62; the water outlet section 5 includes a spatial guide vane inner cover plate 51, the spatial guide vane inner cover plate 51, the bearing 7, the bearing cover 10, and the bushing 11 enclose the bearing 7 chamber, and an oil return hole 53 is provided at the outlet end of the spatial guide vane inner cover plate 51; the oil return hole 53 is connected to the pressurizable oil tank 151 through the oil return pipe 156 and the return one-way valve 155.

[0041] Furthermore, the pressure correction body 153 includes a pressure correction housing 1531, a pressure correction elastic membrane 1532, and a connecting hole 1533. The pressure correction housing 1531 surrounds the outside of the pressure correction elastic membrane 1532 and its surface is uniformly provided with through connecting holes 1533. The connecting holes 1533 are connected to seawater during pressure correction, and the pressure correction elastic membrane 1532 is connected to the oil inlet pipe 152.

[0042] Furthermore, the diameter of the connecting hole 1533 gradually decreases from the radially outer side to the radially inner side.

[0043] Furthermore, the liquid inlet one-way pressure boosting valve 154 includes a valve body 1541, a valve core 1542, a valve ball 1543, a valve body spring 1544, and a valve outlet seat 1545. The valve core 1542 is installed inside the valve body 1541. The valve ball 1543, the valve body spring 1544, and the valve outlet seat 1545 are arranged sequentially inside the valve core 1542. Multiple three-dimensional twisted forward-inclined blades 15451 are arranged on the outer circumference of the valve outlet seat 1545. A gradually narrowing pressure boosting hole 15453 is arranged at the axial center of the valve outlet seat 1545. A through jet hole 15452 inclined towards the axial center is arranged inside the valve outlet seat 1545.

[0044] Furthermore, the impeller 4 includes an upper impeller cover plate 41, inlet blades 42, and a lower impeller cover plate 43. The outlet section 5 also includes a spatial guide vane outer cover plate 52. The pressure balancing structure 16 of the upper impeller cover plate is located in the cavity enclosed by the spatial guide vane outer cover plate 52, the motor rotor 3, and the upper impeller cover plate 41. It includes a balance body 1615 disposed in the cavity and a first upper cover plate balance ring 1611, a first upper cover plate water outlet hole 1612, a second upper cover plate balance ring 1613, and a second upper cover plate water outlet hole 1614 sequentially disposed at the outlet end of the upper impeller cover plate 41. The balance body 1615 is close to the blades. The side of the wheel 4 is provided with two auxiliary balancing rings that cooperate with the first upper cover plate balancing ring 1611 and the second upper cover plate balancing ring 1613 respectively. There is an axial gap between the two auxiliary balancing rings and the first upper cover plate balancing ring 1611 and the second upper cover plate balancing ring 1613. The cavity between the balancing body 1615 and the impeller upper cover plate 41 is divided into a first balancing cavity that is axially closer to the motor rotor 3 and a second balancing cavity that is farther away from the motor rotor 3. The water outlet hole 1612 of the first upper cover plate is in fluid communication with the first balancing cavity, and the water outlet hole 1614 of the second upper cover plate is in fluid communication with the second balancing cavity.

[0045] Furthermore, the diameter of the water outlet hole 1612 of the first upper cover plate is greater than the diameter of the water outlet hole 1614 of the second upper cover plate.

[0046] Furthermore, the side of the balance body 1615 away from the impeller 4 is provided with a back guide plate that cooperates with the groove of the motor rotor 3 to achieve auxiliary balancing and circulation guidance.

[0047] Furthermore, a first balance spring 1616 is provided between the side of the balance body 1615 away from the impeller 4 and the motor rotor 3, and a second balance spring 1617 is provided between the balance body 1615 and the outer cover plate 52 of the space guide vane.

[0048] Furthermore, the spring constant of the first balance spring 1616 is smaller than that of the second balance spring 1617.

[0049] The second balancing chamber mainly relieves pressure and balances pressure through the gap between the balancing body 1615 and the impeller upper cover plate 41. In addition to maintaining pressure balance, the first balancing chamber also circulates, cools, and relieves pressure through the gap between the first upper cover plate balancing ring 1611 and the auxiliary balancing ring, the gap between the balancing body 1615 and the motor rotor 3, and the gap between the balancing body 1615 and the outer cover plate 52 of the space guide vane, so as to ensure the efficient operation of the motor rotor 3.

[0050] Furthermore, the impeller lower cover plate pressure balancing structure 17 is located in the cavity enclosed by the space guide vane inner cover plate 51 and the impeller lower cover plate 43. It includes an axial cylinder 171 and a planar annulus 172 disposed on the inner side wall of the space guide vane inner cover plate 51. The axial cylinder 171 and the planar annulus 172 are fixedly connected at one end and enclose the space guide vane inner cover plate 51 to form a triangular-like balancing chamber. The side of the axial cylinder 171 near the space guide vane inner cover plate 51 is fixedly connected to the space guide vane inner cover plate 51 by a third balancing spring 173 away from the planar annulus 172 and a fourth balancing spring 174 near the planar annulus 172.

[0051] Furthermore, the spring constant of the third balance spring 173 is greater than that of the fourth balance spring 174.

[0052] Furthermore, the planar annular body 172 is provided with an axially penetrating flow hole 175, and the inner cover plate 51 of the spatial guide vane is provided with a penetrating swirling hole 176 that communicates with the triangular-like balance chamber. The swirling hole 176 rotates in the same direction as the spatial guide vane.

[0053] Furthermore, a centrifugal blade 177 is provided on the side of the impeller lower cover plate 43 near the triangular balance chamber, and the centrifugal blade 177 corresponds to the planar annular body 172.

[0054] Furthermore, a concave wear-resistant ring 178 is provided at the outlet end of the impeller lower cover plate 43, and a convex wear-resistant ring 179 is provided at the inlet end of the space guide vane inner cover plate 51. The two form a concave-convex fit to achieve the balance of liquid backflow in the triangular balance chamber.

[0055] The fluid flows back through the gap between the swirling orifice 176, the triangular-shaped balance chamber, the flow passage 175, the centrifugal blade 177, the concave wear-resistant ring 178, and the convex wear-resistant ring 179 in sequence to maintain pressure balance.

[0056] Furthermore, filtration structures can be installed at the inlet ends of the swirl hole 176, the first upper cover plate outlet hole 1612, and the second upper cover plate outlet hole 1614 to improve flow efficiency.

[0057] The isobaric sealing structure of this invention comprises a pressurizable oil tank, an oil inlet pipe, a pressure correction body, an inlet one-way pressure boosting valve, a return one-way valve, and a return oil pipe, forming a closed-loop oil circuit system. An oil inlet channel is located at the pump shaft center, connecting to the bearing chamber formed by the inner cover plate of the spatial guide vane, the bearing, the bearing cap, and the shaft sleeve via an oil inlet hole. A return oil hole is located at the outlet end of the inner cover plate of the spatial guide vane, connecting to the pressurizable oil tank via a return oil pipe and a return one-way valve. This layout forms a directional circulation path of "oil inlet at the shaft center → lubrication in the chamber → oil return from the cover plate," ensuring that the lubricating oil preferentially reaches the bearing friction pair, effectively improving lubrication and cooling efficiency.

[0058] The pressure correction unit consists of a pressure correction shell, a pressure correction elastic diaphragm, and connecting holes evenly distributed on the shell surface. The diameter of the connecting holes gradually decreases from the radially outer side to the radially inner side. During pressure correction, the holes are connected to seawater. The pressure correction elastic diaphragm is connected to the oil inlet pipe. This structure uses the elastic diaphragm as a pressure sensing element to transmit seawater pressure to the bearing chamber through the oil inlet pipe. This enables the bearing chamber oil pressure to follow the deep-sea environment pressure in real time, passively, and without external control devices, eliminating the huge pressure difference between the inside and outside, and preventing lubricating oil leakage and seawater intrusion.

[0059] The inlet one-way pressure boosting valve integrates a valve housing, valve core, valve ball, valve body spring, and valve outlet seat. Multiple three-dimensional twisted forward-inclined blades are located on the outer circumference of the outlet seat to guide and accelerate flow. A tapered pressure boosting orifice is located at the axis to achieve localized pressure boosting. A through-jet orifice inclined towards the axis is located within the seat to achieve directional and enhanced pressure boosting. This valve integrates four functions—one-way check valve, flow guidance, pressure boosting, and jet injection—into a single component. It ensures unidirectional oil flow while achieving localized pressure boosting and precise lubrication of bearing components, significantly enhancing the sealing reliability and operational stability of the system under extreme deep-sea conditions.

[0060] The impeller upper cover pressure balancing structure of this invention is located within a cavity enclosed by a spatial guide vane outer cover, a motor rotor, and an impeller upper cover. It mainly includes a balancing body and a first upper cover balance ring, a first upper cover water outlet, a second upper cover balance ring, and a second upper cover water outlet, sequentially arranged at the outlet end of the impeller upper cover. Two auxiliary balance rings are provided on the side of the balancing body near the impeller, respectively cooperating with the first and second upper cover balance rings, with axial clearance maintained between the two sets of balance rings. The cavity between the balancing body and the impeller upper cover is divided into a first balance cavity near the motor rotor and a second balance cavity away from the motor rotor. The first upper cover water outlet is in fluid communication with the first balance cavity, and the second upper cover water outlet is in fluid communication with the second balance cavity. This structure, through the cooperation of the two balance rings and two balance cavities, establishes a graded pressure regulation mechanism at the impeller upper cover.

[0061] This invention utilizes a differentiated orifice design between the first and second upper cover plate outlet holes—the first outlet hole diameter is larger than the second—to create a controllable pressure difference between the media in the two balancing chambers. This generates a balancing force on the balancing body that is opposite to the axial force of the impeller. When the high-pressure medium at the impeller's upper cover plate enters the corresponding balancing chamber through outlet holes of different diameters, the pressure in the two chambers is adjusted to different levels due to the different outflow capacities. This pressure difference acts on the balancing body and its auxiliary balancing ring, generating a reverse axial thrust, thus achieving adaptive cancellation of the enormous axial force on the impeller. This structure requires no external power source, relying entirely on the pump's own hydraulic parameters to achieve graded balancing and precise control of the axial force.

[0062] A back guide plate, matching the motor rotor slot, is installed on the side of the balancing body away from the impeller. This utilizes the hydrodynamic pressure effect generated by the rotor rotation to achieve auxiliary balancing and circulation guidance, further enhancing balance stability. Simultaneously, a first balancing spring is installed between the balancing body and the motor rotor, and a second balancing spring is installed between the balancing body and the outer cover plate of the spatial guide vane. The stiffness coefficient of the first balancing spring is smaller than that of the second. This differentiated dual-spring design allows the balancing body to adaptively adjust the balancing gap with minute axial displacements when axial force fluctuates, resulting in excellent dynamic response performance. In extreme operating conditions or sudden pressure changes, the second balancing spring, with its larger stiffness coefficient, acts as a rigid limiter, preventing excessive displacement of the balancing body that could lead to collisions or jamming, ensuring structural safety. The two work together to achieve a balance between flexible adaptive adjustment and rigid safety limiting. Furthermore, the recirculation structure also enables efficient cooling of the motor rotor.

[0063] The impeller lower cover pressure balancing structure of this invention is located within a cavity enclosed by the inner cover plate of the spatial guide vane and the impeller lower cover plate. It mainly includes an axial cylinder and a planar annulus fixedly connected to the inner wall of the inner cover plate of the spatial guide vane. Both are fixedly connected at one end and, together with the inner cover plate, form a triangular-like balancing chamber. The side of the axial cylinder closest to the inner cover plate of the spatial guide vane is fixedly connected to the inner cover plate via a third balancing spring away from the planar annulus and a fourth balancing spring closer to the planar annulus, with the stiffness coefficient of the third balancing spring being greater than that of the fourth balancing spring. This differentiated spring design causes the axial cylinder and the planar annulus to deflect or tilt when subjected to axial force, thereby adaptively adjusting the volume and pressure of the triangular-like balancing chamber to achieve a dynamic balance response.

[0064] This invention features a swirling orifice connected to a triangular-shaped balance chamber within the inner cover plate of a spatial guide vane. The swirling orifice rotates in the same direction as the guide vane, allowing the high-pressure medium from the guide vane outlet to enter the balance chamber in the same swirling direction as the mainstream. The centrifugal effect of the swirling flow establishes a pressure gradient within the chamber. Simultaneously, an axially penetrating flow hole is provided on the planar annular body, and centrifugal blades corresponding to the planar annular body are positioned on the lower cover plate of the impeller near the triangular-shaped balance chamber. As the impeller rotates, the centrifugal blades exert centrifugal pressure on the liquid within the chamber, guiding the fluid to circulate and exit. This, combined with the swirling pressure introduced by the swirling orifice, creates a reverse axial thrust, effectively counteracting part of the axial force in the direction of the lower cover plate. The flow hole also serves as a throttling and pressure-relief channel, regulating the pressure level within the chamber and preventing excessive pressure from causing balance failure.

[0065] This invention features a concave wear-resistant ring at the outlet end of the impeller's lower cover plate and a convex wear-resistant ring at the inlet end of the inner cover plate of the spatial guide vane, forming a concave-convex axial sealing structure. This concave-convex wear-resistant ring fit not only serves as a balanced sealing interface for liquid backflow within the triangular-shaped balance chamber, effectively controlling leakage of high-pressure liquid into the low-pressure area and ensuring the pressure-building capacity of the balance chamber, but also extends the leakage path by utilizing the tortuous gap formed by the concave-convex fit, further reducing the leakage amount. Furthermore, the wear-resistant rings are made of a hard, wear-resistant material, significantly improving the structure's wear resistance in deep-sea sandy environments and extending the service life of the balance structure.

[0066] The above embodiments are illustrative of the present invention and not intended to limit the invention. It is understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An isobaric sealing and pressure balancing structure for a deep-sea pump, comprising an inlet section (1), a motor stator (2), a motor rotor (3), an impeller (4), an outlet section (5), a shaft (6), a bearing (7), an outlet section sealing ring (8), a rotor sealing ring (9), a bearing cover (10), a shaft sleeve (11), a mechanical seal (12), a spring washer (13), and a key (14); the inlet section (1), impeller (4), and outlet section (5) are arranged sequentially along the fluid flow direction; one end of the shaft (6) is fixedly mounted with the impeller (4) via the key (14), and the other end is mounted with the outlet section (5) via the bearing (7); the bearing cover (10) 10) A bearing (7) is fixed at the inlet end of the outlet section (5). The inner ring of the bearing cover (10) is fixedly installed on the shaft (6) through the bushing (11) and the mechanical seal (12). One end of the bushing (11) abuts against the bearing (7), and the other end abuts against the impeller (4) through the spring washer (13). An outlet section sealing ring (8) and a rotor sealing ring (9) are provided between the motor rotor (3) and the outlet section (5). The motor rotor (3) is fixedly installed on the outside of the cover plate of the impeller (4). The motor stator (2) is located on the radial outside of the motor rotor (3) and its axial ends are fixedly connected to the inlet section (1) and the outlet section (5) respectively. The feature is that: It also includes an isobaric sealing structure (15), an impeller upper cover pressure balance structure (16), and an impeller lower cover pressure balance structure (17); the isobaric sealing structure (15) uses the pressure balance principle to make the pressure inside the bearing structure consistent with the seawater pressure; the impeller upper cover pressure balance structure (16) and the impeller lower cover pressure balance structure (17) are linked efficiently to achieve dynamic pressure balance of the impeller.

2. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 1, characterized in that, The isobaric sealing structure (15) includes a pressurizable oil tank (151), an oil inlet pipe (152), a pressure correction body (153), an inlet one-way pressure boosting valve (154), a return one-way valve (155), and a return oil pipe (156); an oil inlet channel (61) is provided at the shaft center of the shaft (6), and the oil inlet channel (61) is connected to the bearing (7) chamber through an oil inlet hole (62); the water outlet section (5) includes a space guide vane inner cover plate (51), the space guide vane inner cover plate (51), the bearing (7), the bearing cover (10), and the bushing (11) enclose the bearing (7) chamber, and a return oil hole (53) is provided at the outlet end of the space guide vane inner cover plate (51); the return oil hole (53) is connected to the pressurizable oil tank (151) through the return oil pipe (156) and the return one-way valve (155).

3. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 2, characterized in that, The pressure correction body (153) includes a pressure correction housing (1531), a pressure correction elastic membrane (1532), and a connecting hole (1533). The pressure correction housing (1531) surrounds the outside of the pressure correction elastic membrane (1532) and its surface is uniformly provided with through connecting holes (1533). The connecting holes (1533) are connected to seawater during pressure correction. The pressure correction elastic membrane (1532) is connected to the oil inlet pipe (152). The diameter of the connecting holes (1533) gradually decreases from the radial outer side to the radial inner side.

4. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 3, characterized in that, The liquid inlet one-way pressure boosting valve (154) includes a valve body (1541), a valve core (1542), a valve ball (1543), a valve body spring (1544), and a valve outlet seat (1545). The valve core (1542) is installed inside the valve body (1541). The valve ball (1543), valve body spring (1544), and valve outlet seat (1545) are arranged in sequence inside the valve core (1542). Multiple three-dimensional twisted forward-inclined blades (15451) are arranged on the outer circumference of the valve outlet seat (1545). A gradually narrowing pressure boosting hole (15453) is arranged at the axis of the valve outlet seat (1545). A through jet hole (15452) inclined towards the axis is arranged inside the valve outlet seat (1545).

5. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 4, characterized in that, The impeller (4) includes an upper impeller cover plate (41), inlet blades (42), and a lower impeller cover plate (43). The outlet section (5) also includes a space guide vane outer cover plate (52). The pressure balance structure (16) of the upper impeller cover plate is located in the cavity enclosed by the space guide vane outer cover plate (52), the motor rotor (3), and the upper impeller cover plate (41). It includes a balance body (1615) set in the cavity and a first upper cover plate balance ring (1611), a first upper cover plate water outlet hole (1612), a second upper cover plate balance ring (1613), and a second upper cover plate water outlet hole (1614) set sequentially at the outlet end of the upper impeller cover plate (41). The side of the balance body (1615) near the impeller (4) is provided with the first upper cover plate balance ring (1611) and the second upper cover plate balance ring (1613) respectively. Two auxiliary balancing rings are provided to cooperate with the first upper cover plate balancing ring (1611) and the second upper cover plate balancing ring (1613). The cavity between the balancing body (1615) and the impeller upper cover plate (41) is divided into a first balancing cavity that is axially close to the motor rotor (3) and a second balancing cavity that is far away from the motor rotor (3). The water outlet hole (1612) of the first upper cover plate is in fluid communication with the first balancing cavity, and the water outlet hole (1614) of the second upper cover plate is in fluid communication with the second balancing cavity. The diameter of the water outlet hole (1612) of the first upper cover plate is greater than the diameter of the water outlet hole (1614) of the second upper cover plate. The side of the balancing body (1615) away from the impeller (4) is provided with a back guide plate that cooperates with the groove of the motor rotor (3) to achieve auxiliary balancing and circulation guidance.

6. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 5, characterized in that, A first balance spring (1616) is provided between the side of the balance body (1615) away from the impeller (4) and the motor rotor (3), and a second balance spring (1617) is provided between the balance body (1615) and the outer cover plate (52) of the space guide vane.

7. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 6, characterized in that, The spring constant of the first balance spring (1616) is smaller than that of the second balance spring (1617).

8. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 7, characterized in that, The impeller lower cover pressure balance structure (17) is located in the cavity enclosed by the space guide vane inner cover plate (51) and the impeller lower cover plate (43). It includes an axial cylinder (171) and a planar ring (172) set on the inner side wall of the space guide vane inner cover plate (51). The axial cylinder (171) and the planar ring (172) are fixedly connected at one end and enclosed by the space guide vane inner cover plate (51) to form a triangular balance chamber. The side of the axial cylinder (171) near the space guide vane inner cover plate (51) is fixedly connected to the space guide vane inner cover plate (51) through a third balance spring (173) away from the planar ring (172) and a fourth balance spring (174) near the planar ring (172).

9. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 8, characterized in that, The spring constant of the third balance spring (173) is greater than that of the fourth balance spring (174).

10. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 9, characterized in that, The planar annular body (172) is provided with an axially penetrating flow hole (175), and the inner cover plate (51) of the space guide vane is provided with a penetrating swirling hole (176) that communicates with the triangular balance chamber. The swirling hole (176) has the same swirling direction as the space guide vane.

11. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 10, characterized in that, Centrifugal blades (177) are provided on the side of the impeller lower cover plate (43) near the triangular balance chamber, and the centrifugal blades (177) correspond to the planar annular body (172).

12. The isobaric sealing and pressure balancing structure for a deep-sea pump as described in claim 11, characterized in that, The outlet end of the impeller lower cover plate (43) is provided with a concave wear-resistant ring (178), and the inlet end of the space guide vane inner cover plate (51) is provided with a convex wear-resistant ring (179). The two form a concave-convex fit to achieve the balance of liquid reflux in the triangular balance chamber.

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