A pump thrust device for balancing axial forces

Abstract

The present application relates to vertical multi-stage centrifugal pump technical field, especially to a kind of pump thrust device for balancing axial force, including dynamic ring assembly and the static ring assembly being arranged below dynamic ring assembly, high-pressure seal structure is also arranged between dynamic ring assembly and static ring assembly, high-pressure seal structure includes buoyancy control unit, buoyancy control unit is arranged in the inner cavity of static ring assembly, buoyancy control unit includes the high-pressure water channel being communicated with high-pressure water cavity;Sealing unit, sealing unit includes a high-pressure chamber, high-pressure chamber bottom is connected with buoyancy control unit, high-pressure chamber top is equipped with the water film isolation part being connected with dynamic ring assembly.This application optimizes the specific structure of dynamic ring assembly and static ring assembly and the cooperation between them, solves the problem of weakened sealing between dynamic ring assembly and static ring assembly due to long-term friction pair between dynamic ring assembly and static ring assembly, protects vertical multi-stage centrifugal pump under the assistance of pump thrust device, balances axial force, and has longer service life.

Description

Technical Field

[0001] This invention relates to the field of vertical multistage centrifugal pump technology, and in particular to a pump thrust device for balancing axial forces. Background Technology

[0002] Lightweight vertical multistage centrifugal pumps are industrial pumps mainly used in high-rise pressurization, industrial cleaning systems, and cooling systems. In the existing structure of vertical multistage centrifugal pumps, the axial force points towards the impeller outlet. The lower stages experience smaller axial forces, which act on the motor bearings, with the bearings partially balancing the axial force. Higher stages experience larger axial forces; relying solely on the bearings for this load would severely impact their lifespan, potentially damaging the entire pump, reducing customer satisfaction, and harming the company's quality and reputation. To address this issue, axial force balancing devices are typically installed in the inlet and outlet sections of lightweight vertical multistage centrifugal pumps to prevent pump damage caused by relying solely on the motor bearings for axial force balancing.

[0003] For example, the domestic invention patent with application number CN202110175033.X discloses a novel axial force balancing device for a multi-stage pump, which relates to the field of vertical multi-stage centrifugal pumps. It includes a dynamic ring assembly and a stationary ring assembly. The dynamic ring assembly has a cavity at the bottom to accommodate the dynamic ring. The top of the transmission seat has a pump shaft hole that communicates with the cavity. The pump shaft is inserted into the pump shaft hole and connected and fixed to the inner wall of the transmission seat to drive the dynamic ring assembly. The stationary ring assembly has a stationary ring embedded in the upper part of the sealing seat in a slotted manner. One end of the anti-rotation pin is inserted into the sealing seat, and the other end of the anti-rotation pin is inserted into the stationary ring to prevent relative rotation between the stationary ring and the sealing seat. A high-pressure liquid chamber is provided in the sealing seat. Several connecting holes are radially opened on the outer wall of the sealing seat. One end of the connecting hole communicates with the high-pressure liquid chamber, and the other end communicates with the outlet. Although a friction pair is generated between the fixed stationary and rotating rings to seal the low-pressure liquid at the inlet and the high-pressure liquid at the outlet; the rotating ring assembly rotates with the pump shaft, while the stationary ring assembly connects to the inlet and outlet sections to form a bottom seal. The high-pressure liquid at the outlet returns to the outlet of the inlet and outlet section through the pressure-resistant cylinder, and then reaches the high-pressure liquid chamber through the connection hole on the sealing seat, creating a pressure difference with the low-pressure liquid at the inlet. The direction of the pressure is opposite to the direction of the axial force, thus achieving the effect of balancing part of the axial force. However, due to wear between the rotating and stationary ring assemblies, the sealing performance between the rotating and stationary ring assemblies weakens over long-term use, causing the axial force balancing device to cease normal operation. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a pump thrust device and a vertical multistage centrifugal pump for balancing axial forces. By optimizing the specific structure and matching relationship between the dynamic and static ring assemblies, the invention solves the problem of weakened sealing between the dynamic and static ring assemblies due to long-term friction between them. This protects the vertical multistage centrifugal pump, allowing it to balance axial forces with the assistance of the pump thrust device, and also extends its service life.

[0005] To achieve the above objectives, the present invention provides a pump thrust device for balancing axial forces, comprising a dynamic ring assembly and a stationary ring assembly disposed below the dynamic ring assembly. The dynamic ring assembly includes a thrust disc, a dynamic ring rubber ring, a dynamic sealing ring, and a fixing sleeve. A high-pressure sealing structure is further provided between the dynamic ring assembly and the stationary ring assembly. The high-pressure sealing structure includes:

[0006] A buoyancy control unit is disposed in the inner cavity of the static ring assembly, and the buoyancy control unit includes a high-pressure water channel communicating with the high-pressure water inlet chamber;

[0007] A sealing unit, the sealing unit including a high-pressure chamber, the bottom of the high-pressure chamber being connected to the buoyancy control unit, and the top of the high-pressure chamber being provided with a water film isolation part connected to the dynamic ring assembly.

[0008] Furthermore, the buoyancy control unit is a buoyancy base plate with the high-pressure water inlet. The buoyancy control unit has an upwardly protruding connecting ring near its outer periphery. After the buoyancy control unit floats upward under the high-pressure thrust of the high-pressure water inlet, it is connected to the slot.

[0009] Furthermore, the stationary ring assembly includes an upper sealing part and a lower sealing base. The upper sealing part and the lower sealing base are assembled to form multiple high-pressure water inlet channels and a high-pressure water inlet cavity. The multiple high-pressure water inlet channels are connected to the high-pressure water inlet cavity. The high-pressure sealing structure is connected in the inner cavity of the upper sealing part, and the high-pressure sealing structure can move up and down relative to the inner cavity of the upper sealing part.

[0010] Furthermore, the upper end of the inner cavity of the upper sealing part is provided with a downwardly recessed support groove, the support groove is provided with a central anti-rotation pin, the sealing unit is provided with a static sealing ring that protrudes outward and is connected to the support groove, and the static sealing ring is provided with a stop recess that is recessed inward and is connected to the central anti-rotation pin.

[0011] Furthermore, the connection between the sealing unit and the dynamic ring assembly is provided with a multi-stage pressure regulating section. The multi-stage pressure regulating section includes a primary pressure reducing groove and a final pressure reducing groove that are connected to each other from bottom to top. The primary pressure reducing groove forms a primary pressure reducing channel, and the final pressure reducing groove forms a final pressure reducing channel.

[0012] Furthermore, the inner diameter of the primary step-down channel is smaller than the inner diameter of the ultimate step-down channel.

[0013] Furthermore, the inner diameter of the ultimate pressure reduction channel is larger than the inner diameter of the connection between the dynamic sealing ring and the multi-stage pressure regulating part.

[0014] Furthermore, the portion of the dynamic sealing ring extending beyond the top of the multi-stage pressure regulating section at the connection point with the multi-stage pressure regulating section is provided with a protruding or recessed guide vane facing the multi-stage pressure regulating section.

[0015] Furthermore, the guide vane rotates and retracts toward the central axis of the sealing unit.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention solves the problem of weakened sealing between the dynamic and static ring components due to long-term friction between them by optimizing the specific structure and fit between the dynamic and static ring components. This protects the vertical multistage centrifugal pump, balances axial force with the assistance of the pump thrust device, and has a longer service life.

[0018] 2. This invention adds a high-pressure sealing structure through optimized design. By using a buoyancy control unit in conjunction with the stationary ring assembly, the high-pressure water zone in the stationary ring assembly provides an upward thrust to the buoyancy control unit, ensuring a stable connection between the high-pressure sealing structure and the moving ring assembly. This avoids the problem of reduced sealing performance between the moving and stationary ring assemblies due to wear during long-term use, which could prevent the axial force balancing device from continuing to function properly.

[0019] 3. The part of the dynamic sealing ring that extends out of the top of the multi-stage pressure regulating part and faces the multi-stage pressure regulating part is provided with a protruding or recessed guide vane. When two water bodies with different pressures come into contact, the guide vane structure guides the liquid flow and forms a stable water film.

[0020] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of a pump thrust device for balancing axial force according to the present invention;

[0022] Figure 2 This is a cross-sectional view of the dynamic ring assembly in a pump thrust device for balancing axial force according to the present invention;

[0023] Figure 3 This is a cross-sectional view of a high-pressure sealing structure in a pump thrust device for balancing axial force according to the present invention;

[0024] Figure 4This is a cross-sectional view of the stationary ring assembly in a pump thrust device for balancing axial force according to the present invention;

[0025] Figure 5 This is a bottom view of the dynamic sealing ring in a pump thrust device for balancing axial forces according to the present invention.

[0026] In the diagram: 1. Dynamic ring assembly; 101. Thrust disc; 102. Dynamic ring rubber ring; 103. Dynamic sealing ring; 1031. Guide vane; 104. Fixing sleeve; 2. High-pressure sealing structure; 201. Buoyancy control unit; 2011. High-pressure water inlet; 2012. Connecting ring; 202. Sealing unit; 2021. High-pressure chamber; 2022. Slot; 2023. Static sealing ring; 2024. Stop recess; 2025. Multi-stage pressure regulating section; 2025a. Primary pressure reducing groove; 2025b. Final pressure reducing groove; 203. Water film isolation section; 3. Static ring assembly; 3a. Upper sealing section; 3a1. Support groove; 3a2. Middle anti-rotation pin; 3b. Lower sealing base; 3D. High-pressure water inlet channel; 3Q. High-pressure water inlet chamber. Detailed Implementation

[0027] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings. However, the scope of protection of the present invention is not limited to the scope described below.

[0028] The thrust structure in a vertical multistage centrifugal pump serves the following functions:

[0029] Axial force: Centrifugal pumps generate axial force during operation, which is the thrust generated by the liquid flow. The thrust structure can withstand these axial forces, preventing them from adversely affecting the pump's stability and lifespan. Thrust balance: In vertical multistage centrifugal pumps, the thrust generated within the pump is often unbalanced due to the action of multiple impellers. A properly designed thrust structure can balance the pump's positive and negative thrust, thereby avoiding instability and vibration within the pump.

[0030] Reference Figure 1-5 The diagram shows a pump thrust device for balancing axial forces.

[0031] A pump thrust device for balancing axial forces includes a dynamic ring assembly 1 and a stationary ring assembly 3 disposed below the dynamic ring assembly 1. The dynamic ring assembly 1 includes a thrust disc 101, a dynamic ring rubber ring 102, a dynamic sealing ring 103, and a fixing sleeve 104. A high-pressure sealing structure 2 is further provided between the dynamic ring assembly 1 and the stationary ring assembly 3. The high-pressure sealing structure 2 includes:

[0032] The buoyancy control unit 201 is disposed in the inner cavity of the stationary ring assembly 2. The buoyancy control unit 201 includes a high-pressure water channel communicating with the high-pressure water inlet chamber 3Q. The buoyancy control unit 201 is a buoyancy base plate with a high-pressure water inlet 2011. The buoyancy control unit 201 has an upwardly protruding connecting ring 2012 near its outer periphery. After the buoyancy control unit 201 floats upward under the high pressure thrust of the high-pressure water inlet, it cooperates with the slot 2022 for connection.

[0033] refer to Figure 1 As shown in the diagram, the straight line indicated by the arrows indicates the direction of water flow. Water enters through multiple high-pressure inlet channels 3D, passes through the high-pressure inlet chamber 3Q, and applies an upward thrust to the buoyancy control unit 201. Simultaneously, high-pressure water is injected into the inner cavity of the sealing unit 202 through the high-pressure water inlet 2011, forming a high-pressure water zone within the sealing unit 202. The inner cavity of the rotating ring assembly 1 is a low-pressure zone. A water film isolation section 203 is formed at the connection between the rotating ring assembly 1 and the sealing unit 202. The water film isolation section 203 isolates the high-pressure water zone, preventing water from flowing from the high-pressure water zone inside the sealing unit 202 into the low-pressure zone inside the rotating ring assembly 1. Simultaneously, the water film in the vertical multistage centrifugal pump protects the bearings, reduces leakage, and regulates axial force.

[0034] This invention adds a high-pressure sealing structure 2 through optimized design. The buoyancy control unit 201 works in conjunction with the stationary ring assembly 3. The high-pressure water zone in the stationary ring assembly 3 provides an upward thrust to the buoyancy control unit 201, which makes the high-pressure sealing structure 2 and the moving ring assembly 1 stably connected. This avoids the problem that wear between the moving ring assembly 1 and the stationary ring assembly 3 will weaken the sealing performance between the moving ring assembly and the stationary ring assembly during long-term use, thus preventing the axial force balancing device from continuing to work normally.

[0035] The stationary ring assembly 3 includes an upper sealing part 3a and a lower sealing base 3b. The upper sealing part 3a and the lower sealing base 3b are assembled to form multiple high-pressure water inlet channels 3D and a high-pressure water inlet cavity 3Q. The multiple high-pressure water inlet channels 3D are connected to the high-pressure water inlet cavity 3Q. The high-pressure sealing structure 2 is connected in the inner cavity of the upper sealing part 3a, and the high-pressure sealing structure 2 can move up and down relative to the inner cavity of the upper sealing part 3a.

[0036] The sealing unit 202 includes a high-pressure chamber 2021. The bottom of the high-pressure chamber 2021 is connected to the buoyancy control unit 201, and the top of the high-pressure chamber 2021 is provided with a water film isolation part 203 connected to the dynamic ring assembly 1.

[0037] This application optimizes the specific structure of the dynamic ring assembly 1 and the stationary ring assembly 3 and their matching relationship, solves the problem of weakened sealing between the dynamic ring assembly 1 and the stationary ring assembly 3 due to long-term friction between them, protects the vertical multistage centrifugal pump, balances axial force with the assistance of the pump thrust device, and has a longer service life.

[0038] The upper end of the inner cavity of the upper sealing part 3a is provided with a downwardly recessed support groove 3a1. A central anti-rotation pin 3a2 is provided on the support groove 3a1. A static sealing ring 2023 protrudes outward on the sealing unit 202 and is connected to the support groove 3a1. A stop recess 2024 is recessed inward on the static sealing ring 2023 and is connected to the central anti-rotation pin 3a2. The central anti-rotation pin 3a2 and the stop recess 2024 are connected to each other to limit the sealing unit 202, preventing the rotating ring assembly 1 connected to the motor shaft from rotating during the operation of the vertical multistage centrifugal pump, which would cause the high-pressure sealing structure 2 connected to the rotating ring assembly 1 to rotate as well, thus keeping the high-pressure sealing structure 2 and the static ring assembly 3 relatively stationary.

[0039] The sealing unit 202 is provided with a multi-stage pressure regulating section 2025 at the connection between it and the dynamic ring assembly 1. The multi-stage pressure regulating section 2025 includes a primary pressure reducing groove 2025a and a final pressure reducing groove 2025b that are connected to each other from bottom to top. The primary pressure reducing groove 2025a forms a primary pressure reducing channel, and the final pressure reducing groove 2025b forms a final pressure reducing channel.

[0040] Since the water area of ​​the multi-stage pressure regulating section 2025 is a high-pressure area and the area of ​​the dynamic sealing ring 103 is a low-pressure area, a water film can be formed between the multi-stage pressure regulating section 2025 and the dynamic sealing ring 103. In this application's technical solution, the water film achieves the following effects: protection of the bearing, reduction of leakage, and adjustment of axial force.

[0041] Bearing protection: The water film in the thrust structure forms a protective layer in front of the bearing, preventing high-pressure liquid from entering the bearing area. This prevents direct impact and wetting of the bearing by the liquid, reducing wear and damage. The water film also provides some cooling, lowering the bearing temperature and extending its service life.

[0042] Reduced leakage: The water film in the thrust structure forms a sealing layer, effectively reducing liquid leakage from high-pressure areas to low-pressure areas. The water film acts as a barrier against high-pressure liquid leakage, preventing energy waste and environmental pollution. Furthermore, by controlling the thickness and pressure of the water film, leakage can be further reduced, improving pump efficiency and performance.

[0043] Adjusting Axial Force: The axial force can be adjusted by changing the thickness and pressure of the water film in the thrust structure. By increasing or decreasing the thickness and pressure of the water film, the force exerted by the liquid on the thrust structure can be changed, thereby adjusting the pump's axial force. This allows the pump to maintain a stable axial force under different operating conditions, avoiding the adverse effects of excessively large or small axial forces on the pump's performance and lifespan.

[0044] In summary, the water film in the structure plays a crucial role in vertical multistage centrifugal pumps by protecting bearings, reducing leakage, and regulating axial force. It prevents liquid from flowing from high-pressure areas to low-pressure areas, protects bearings, reduces leakage, and regulates axial force, providing additional protection and regulation for the normal operation and performance of the centrifugal pump. The water film forms a protective and sealing layer, effectively blocking liquid impact and leakage from the bearings. Furthermore, by adjusting the thickness and pressure of the water film, the axial force can be rationally regulated. These measures all contribute to improving the pump's performance, stability, and lifespan.

[0045] The inner diameter of the primary pressure-reducing channel is smaller than that of the ultimate pressure-reducing channel.

[0046] The inner diameter of the ultimate pressure reduction channel is larger than the inner diameter of the connection between the dynamic sealing ring 103 and the multi-stage pressure regulating part 2025.

[0047] By designing the primary and final pressure-reducing channels with different inner diameters, when...

[0048] refer to Figure 5 As shown, the portion of the dynamic sealing ring 103 extending out of the top of the multi-stage pressure regulating part 2025 at the connection between the dynamic sealing ring 103 and the multi-stage pressure regulating part 2025 is provided with a protruding or recessed guide vane 1031 facing the multi-stage pressure regulating part 2025.

[0049] The guide vane 1031 rotates and retracts toward the central axis of the sealing unit 202.

[0050] At the connection point between the dynamic sealing ring 103 and the multi-stage pressure regulating unit 2025, the portion extending beyond the top of the multi-stage pressure regulating unit 2025 has a protruding or recessed guide vane 1031 facing the multi-stage pressure regulating unit 2025. When two water bodies with different pressures come into contact, the guide vane 1031 guides the liquid flow and forms a stable water film. The inclination angle of the guide vane is designed according to specific production conditions to adapt to different production requirements and produce water films of different thicknesses.

[0051] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A pump thrust device for balancing axial force, comprising a dynamic ring assembly (1) and a stationary ring assembly (3) disposed below the dynamic ring assembly (1), wherein the dynamic ring assembly (1) comprises a thrust disc (101), a dynamic ring rubber ring (102), a dynamic sealing ring (103), and a fixing sleeve (104), characterized in that, A high-pressure sealing structure (2) is also provided between the dynamic ring assembly (1) and the stationary ring assembly (3). The high-pressure sealing structure (2) includes: a buoyancy control unit (201), which is disposed in the inner cavity of the stationary ring assembly (3) and includes a high-pressure water channel communicating with the high-pressure water inlet chamber (3Q); and a sealing unit (202), which includes a high-pressure chamber (2021) and the bottom of the high-pressure chamber (2021) is connected to the buoyancy control unit (201). The high-pressure chamber (2021) is provided with a water film isolation part (203) connected to the moving ring assembly (1) at the top; the buoyancy control unit (201) is a buoyancy base plate with a high-pressure water inlet (2011). The buoyancy control unit (201) is provided with an upwardly protruding connecting ring (2012) near the outer periphery. After the buoyancy control unit (201) floats upward under the high pressure thrust of the high-pressure water inlet, it is connected to the slot (2022). Thus, the adaptive floating mechanism of the buoyancy control unit maintains a stable connection between the high-pressure sealing structure and the moving ring assembly, and extends the service life.

2. The pump thrust device for balancing axial force according to claim 1, characterized in that, The stationary ring assembly (3) includes an upper sealing part (3a) and a lower sealing base (3b). The upper sealing part (3a) and the lower sealing base (3b) are assembled to form multiple high-pressure water inlet channels (3D) and a high-pressure water inlet cavity (3Q). The multiple high-pressure water inlet channels (3D) are connected to the high-pressure water inlet cavity (3Q). The high-pressure sealing structure (2) is connected in the inner cavity of the upper sealing part (3a) and the high-pressure sealing structure (2) can move up and down relative to the inner cavity of the upper sealing part (3a).

3. A pump thrust device for balancing axial force according to claim 2, characterized in that, The upper end of the inner cavity of the upper sealing part (3a) is provided with a downwardly recessed support groove (3a1), and a central anti-rotation pin (3a2) is provided on the support groove (3a1). The sealing unit (202) is provided with a static sealing ring (2023) that is connected to the support groove (3a1) and protrudes outward. The static sealing ring (2023) is provided with a stop recess (2024) that is recessed inward to stop the central anti-rotation pin (3a2).

4. A pump thrust device for balancing axial force according to claim 1 or 3, characterized in that, The sealing unit (202) is provided with a multi-stage pressure regulating section (2025) at the connection between it and the dynamic ring assembly (1). The multi-stage pressure regulating section (2025) includes a primary pressure reducing groove (2025a) and a final pressure reducing groove (2025b) that are connected to each other from bottom to top. The primary pressure reducing groove (2025a) forms a primary pressure reducing channel, and the final pressure reducing groove (2025b) forms a final pressure reducing channel.

5. A pump thrust device for balancing axial force according to claim 4, characterized in that, The inner diameter of the primary step-down channel is smaller than the inner diameter of the ultimate step-down channel.

6. A pump thrust device for balancing axial force according to claim 5, characterized in that, The inner diameter of the ultimate pressure reduction channel is larger than the inner diameter of the connection between the dynamic sealing ring (103) and the multi-stage pressure regulating part (2025).

7. A pump thrust device for balancing axial force according to claim 6, characterized in that, The portion of the dynamic sealing ring (103) extending beyond the top of the multi-stage pressure regulating part (2025) at the connection point with the multi-stage pressure regulating part (2025) is provided with a protruding or recessed guide vane (1031) facing the multi-stage pressure regulating part (2025).

8. A pump thrust device for balancing axial force according to claim 7, characterized in that, The guide vane (1031) rotates and retracts toward the central axis of the sealing unit (202).

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