Axial force balancing structure for centrifugal pump
By incorporating external bosses, L-shaped through holes, and internal bosses into the centrifugal pump, the problem of axial force imbalance between the impeller rear cover plate and the pump cover rear cavity is solved, achieving dynamic axial force balance in the centrifugal pump and improving its reliability and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI KAIQUAN PUMP IND GROUP
- Filing Date
- 2025-05-23
- Publication Date
- 2026-05-15
AI Technical Summary
In centrifugal pumps, the rear cavity formed by the impeller rear cover and the pump cover becomes unbalanced in axial force due to the entry of high-pressure medium, causing axial movement and vibration, reducing service life and increasing maintenance costs.
By setting an outer boss on the pump cover to form a first axial seal with the impeller rear cover plate, and opening multiple L-shaped through holes near the outer boss to counteract the pressure of the high-pressure medium, the pressure of the cavity is adjusted by combining the inner boss and the balance hole to achieve dynamic balance of axial force.
It effectively prevents high-pressure medium from entering the impeller rear chamber at the impeller outlet, reduces the pressure in the impeller rear chamber, achieves axial force balance, and improves the reliability and stability of the centrifugal pump.
Smart Images
Figure CN224245141U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a balancing structure, specifically an axial force balancing structure for centrifugal pumps that can effectively suppress the entry of high-pressure medium at the impeller outlet into the impeller rear cavity while ensuring the hydraulic performance of the centrifugal pump, thereby reducing the pressure in the impeller rear cavity, and can achieve dynamic balance of axial force, thus ensuring the reliable operation of the centrifugal pump. Background Technology
[0002] In the field of centrifugal pump technology, axial force balance is a critical issue. During operation, the impeller rotation generates water pressure at the front and rear cover plates. The presence of the impeller inlet means the rear cover plate experiences a larger area of water force than the front cover plate. Furthermore, due to manufacturing precision issues or pump structure considerations, the rear sealing ring of the impeller has a relatively large gap. This allows more high-pressure media to enter the rear cavity formed by the impeller rear cover plate and the pump cover, resulting in an imbalance of forces acting on the front and rear cover plates. This creates an axial force that consistently points from the rear cover plate towards the front cover plate, especially when the gap in the rear sealing ring is large, leading to a greater difference in axial forces between the front and rear cover plates. This axial force causes axial movement of the pump shaft, resulting in wear and vibration, reducing the service life of the centrifugal pump, and increasing maintenance and replacement costs. Utility Model Content
[0003] To address the aforementioned problems, the main objective of this invention is to provide an axial force balancing structure for centrifugal pumps that can effectively suppress the entry of high-pressure medium at the impeller outlet into the impeller rear chamber while ensuring the hydraulic performance of the centrifugal pump, thereby reducing the pressure in the impeller rear chamber, and can achieve dynamic balance of axial force, thus ensuring the reliable operation of the centrifugal pump.
[0004] This utility model solves the above-mentioned technical problems through the following technical solution: an axial force balancing structure for a centrifugal pump, the axial force balancing structure for a centrifugal pump includes: a centrifugal pump body, an impeller, and a pump cover. The impeller is located in the pump body. The outer diameter of the rear cover plate of the impeller is smaller than the outer diameter of the front cover plate. The front cover plate of the impeller has a front sealing ring, and the rear cover plate of the impeller has a rear sealing ring and a balancing hole. The pump cover has an outer boss near the impeller outlet, and the outer boss and the rear cover plate of the impeller form a first axial seal. The pump cover has a groove on the side near the impeller, and the groove and the rear sealing ring of the impeller form a second axial seal and a third axial seal. The pump cover has multiple through holes near the outer boss, and the through holes connect the pump body cavity, the first axial seal, and the second axial seal. The pump cover has an inner boss near the balancing hole of the impeller.
[0005] In a specific embodiment of this utility model, the outer diameter D of the impeller rear cover plate 2h The value range is: 1.1D k2 ≤D 2h ≤0.9D2, where D k2D1 is the outer diameter of the impeller rear sealing ring, and D2 is the outer diameter of the impeller front cover plate.
[0006] In a specific embodiment of this utility model, the minimum axial distance between the outer boss of the pump cover and the impeller blade is 0.5-3mm.
[0007] In a specific embodiment of this utility model, the through hole is an L-shaped through hole. The center line of the outlet channel on the pump shaft side of the L-shaped through hole is aligned with the center line of the first axial seal. The through holes are evenly distributed along the circumferential direction, and the total flow area of the through holes is not less than the flow area formed by the first axial seal.
[0008] In a specific embodiment of this utility model, there is a cavity C between the through hole and the first axial sealing end face, and the axial distance of the cavity C is not less than the diameter of the through hole.
[0009] In a specific embodiment of this utility model, the outer diameter D of the impeller rear sealing ring k2 The range of values for is: D k1 ≤D k2 ≤0.85D², where D k1 This refers to the outer diameter of the impeller front sealing ring.
[0010] In a specific embodiment of this utility model, the total flow area of the balance holes is not less than the flow area of the third axial seal.
[0011] In a specific embodiment of this utility model, the pump cover has an inner boss near the impeller balance hole. The inner boss is located outside the balance hole, and the design gap between it and the impeller rear cover plate is greater than the axial movement of the pump impeller.
[0012] The positive and progressive effects of this utility model are as follows: Compared with common technologies, the axial force balancing structure for centrifugal pumps provided by this utility model has the following advantages: This utility model effectively suppresses the high-pressure medium at the impeller outlet from entering the cavity formed by the impeller rear cover plate and the pump cover through multiple structural combinations, and can achieve dynamic axial force balance, solving the unstable operating state such as rotor movement caused by excessive axial force on the impeller rear cover plate, thereby improving the reliability of the centrifugal pump. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the overall structure of this utility model.
[0014] Figure 2 for Figure 1 A magnified view of a portion of the image.
[0015] The following are the names corresponding to the reference numerals in this utility model:
[0016] 1. Pump body, 2. Impeller, 3. Pump cover, 4. Main shaft, 5. Transmission key, 6. Screw, 7. Balance hole, 8. Through hole, 9. Cavity A, 10. Cavity B, 11. Cavity C, 12. Cavity D, 13. Outer boss, 14. Inner boss, 15. First axial seal, 16. Second axial seal, 17. Third axial seal, 18. Impeller rear sealing ring, 19. Impeller front sealing ring. Detailed Implementation
[0017] The preferred embodiments of this utility model are given below with reference to the accompanying drawings to illustrate the technical solution of this utility model in detail.
[0018] Figure 1 This is a schematic diagram of the overall structure of this utility model. Figure 2 for Figure 1 A magnified view of a portion, such as Figure 1-2 As shown, this utility model proposes an axial force balancing structure for a centrifugal pump. The axial force balancing structure for a centrifugal pump includes: a centrifugal pump body 1, an impeller 2, and a pump cover 3. The impeller 2 is located inside the pump body 1. The outer diameter of the impeller rear cover plate is smaller than the outer diameter of the front cover plate. The impeller front cover plate has an impeller front sealing ring 15, and the impeller rear cover plate has an impeller rear sealing ring 14 and a balancing hole 7. The pump cover 3 has an outer boss 9 near the impeller outlet. The outer boss 9 and the impeller rear cover plate form a first axial seal 11. The pump cover 3 has a groove on the side near the impeller 2. The groove and the impeller rear sealing ring 14 form a second axial seal 12 and a third axial seal 13. The pump cover 3 has multiple through holes 8 near the outer boss 9. The through holes 8 connect the pump body cavity, the first axial seal 11, and the second axial seal 12. The pump cover 3 has an inner boss 10 near the balancing hole 7 of the impeller.
[0019] like Figure 1 As shown, during pump operation, the impeller 2 is connected to the main shaft 4 via a transmission key 5 and fixed to the main shaft with screws 6, rotating at high speed together with the main shaft 4. The rotating impeller 2 transfers energy to the medium passing through the impeller channel, forming a high-pressure medium at the impeller outlet. The high-pressure medium enters from the impeller outlet into cavity A formed by the impeller front cover plate and the pump body, and cavity D formed by the impeller rear cover plate and the pump cover. In traditional designs, due to the lower impeller inlet pressure and the larger area of the rear cover plate subjected to hydraulic pressure than the front cover plate, coupled with the problem of a large gap in the impeller rear sealing ring due to machining precision or pump structure considerations,
[0020] This causes a large amount of high-pressure medium to enter the rear cavity formed by the impeller rear cover plate and the pump cover, resulting in an imbalance of forces acting on the front and rear cover plates. This generates an axial force from the impeller rear cover plate to the front cover plate, causing axial movement of the rotor.
[0021] This invention provides an axial force balancing structure for a centrifugal pump. Firstly, by reducing the outer diameter of the rear cover plate, the difference in the effective area between the front and rear cover plates is reduced. Simultaneously, to ensure the performance of the centrifugal pump and suppress the entry of high-pressure fluid into cavity D, an outer boss 9 is added to the pump cover to cooperate with the impeller rear cover plate to form a first axial seal 11. However, due to the existence of gaps, high-pressure medium can still enter cavity B. This invention addresses this by opening multiple L-shaped through holes 8 near the outer boss 9. The end face of the through hole 8 and the end face of the first axial seal form cavity C. Cavity B and cavity C are connected through the through holes 8. Since the flow direction of the medium entering cavity C from the outer circumference of the impeller rear cover plate is opposite to the flow direction of the medium entering cavity C from the through holes 8, the pressure of the high-pressure medium is partially reduced. By offsetting and suppressing the pressure reduction, the medium, after its pressure is lowered, experiences further pressure reduction as it passes through the second axial seal 12 and the third axial seal 13, thereby reducing the medium pressure entering cavity D and balancing the axial forces of the front and rear cover plates. Furthermore, to achieve dynamic balance of axial forces under different operating conditions, an inner boss 10 is provided on the pump cover, and a balance hole 7 is provided on the impeller rear cover plate. When the impeller axial force direction is from the front cover plate to the rear cover plate, the impeller moves towards the rear cover plate, reducing the gap a. This decreases the amount of low-pressure medium entering cavity C through the balance hole 7, increasing the pressure in cavity C. Conversely, when the impeller axial force is from the rear cover plate to the front cover plate, the impeller moves towards the front cover plate, increasing the amount of low-pressure medium entering cavity C through the balance hole 7, decreasing the pressure in cavity C. This invention effectively suppresses the entry of high-pressure medium into the impeller rear cavity through multiple combined measures, thereby reducing the axial force in the impeller rear cavity and achieving dynamic balance, thus solving this technical problem.
[0022] Below are some specific parameter examples from the design process:
[0023] The outer diameter D of the impeller rear cover plate of this utility model 2h The value range is: 1.1D k2 ≤D 2h ≤0.9D2, where D k2 D1 is the outer diameter of the impeller rear sealing ring 14, and D2 is the outer diameter of the impeller front cover plate. The purpose of D2 is to reduce the force-bearing area of the impeller rear cover plate, thereby reducing the difference in force-bearing area between the front and rear cover plates of the impeller.
[0024] In order to suppress the high-pressure medium in cavity B from entering cavity C and to ensure the performance of the centrifugal pump, the minimum axial distance between the outer boss of the pump cover and the blade is 0.5-3mm, and not less than the axial movement of the impeller. Under the premise of ensuring the safety margin of axial movement, the smaller value is preferred.
[0025] The pump cover of this utility model has an L-shaped through hole 8 near the outer boss 9. The center line of the outlet channel on the pump shaft side of the through hole 8 is aligned with the center line of the first axial seal 11. The through holes are evenly distributed along the circumference. The total flow area of the through holes 8 is not less than the flow area formed by the first axial seal 11. There is a cavity C between the through hole and the end face of the first axial seal 11. The axial distance of the cavity C is not less than the diameter of the through hole. The high-pressure medium enters the through hole 8 from the cavity B, and the flow direction is opposite to that of the medium flowing through the first axial seal 11, thereby inhibiting the direct flow of the high-pressure medium into the second axial seal 12, the third axial seal 13 and the cavity D.
[0026] This utility model relates to an impeller rear sealing ring with an outer diameter D of 14. k2 The range of values for is: D k1 ≤D k2 ≤0.85D², where D k1 The outer diameter of the impeller front sealing ring 15 is given. The axial clearance between the impeller rear sealing ring 14 and the bottom of the pump cover groove is not less than the axial movement of the impeller. The impeller rear sealing ring 14 and the pump cover groove form a second axial seal 12 and a third axial seal 13, which can further reduce the pressure of the medium flowing from cavity C to cavity D.
[0027] The pump cover of this utility model has an inner boss 10 near the impeller balance hole 7. The inner boss 10 is located outside the balance hole 7. The design gap a between the inner boss 10 and the impeller rear cover plate is greater than the axial movement of the pump impeller. The total flow area of the impeller balance hole 7 is greater than the flow area of the third axial seal 13, so as to adjust the pressure of the cavity D and achieve dynamic balance of axial force under different operating conditions.
[0028] This invention, through a combination of various methods, can effectively balance the axial force of a centrifugal pump, improve rotor operating stability, extend the service life of bearings and mechanical seals, and enhance pump reliability.
[0029] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection of this utility model as defined by the appended claims and their equivalents.
Claims
1. An axial force balancing structure for a centrifugal pump, characterized in that: The centrifugal pump axial force balancing structure includes: a centrifugal pump body, an impeller, and a pump cover. The impeller is located within the pump body. The outer diameter of the impeller rear cover plate is smaller than that of the front cover plate. The impeller front cover plate has an impeller front sealing ring, and the impeller rear cover plate has an impeller rear sealing ring and a balancing hole. The pump cover has an outer boss near the impeller outlet, which forms a first axial seal with the impeller rear cover plate. The pump cover has a groove on the impeller side, which forms a second and third axial seal with the impeller rear sealing ring. The pump cover has multiple through holes near the outer boss, which connect the pump body cavity, the first axial seal, and the second axial seal. The pump cover has an inner boss near the balancing hole of the impeller.
2. The axial force balancing structure for a centrifugal pump according to claim 1, characterized in that: Impeller rear cover outer diameter D 2h The value range is: 1.1D k2 ≤D 2h ≤0.9D2, where D k2 D1 is the outer diameter of the impeller rear sealing ring, and D2 is the outer diameter of the impeller front cover plate.
3. The axial force balancing structure for a centrifugal pump according to claim 1, characterized in that: The minimum axial distance between the outer boss of the pump cover and the impeller blades is 0.5-3mm.
4. The axial force balancing structure for a centrifugal pump according to claim 1, characterized in that: The through hole is an L-shaped through hole. The center line of the outlet channel on the pump shaft side of the L-shaped through hole is aligned with the center line of the first axial seal. The through holes are evenly distributed along the circumference, and the total flow area of the through holes is not less than the flow area formed by the first axial seal.
5. The axial force balancing structure for a centrifugal pump according to claim 4, characterized in that: There is a cavity C between the through hole and the first axial sealing end face, and the axial distance of the cavity C is not less than the diameter of the through hole.
6. The axial force balancing structure for a centrifugal pump according to claim 2, characterized in that: The outer diameter D of the impeller rear sealing ring k2 The range of values for is: D k1 ≤D k2 ≤0.85D², where D k1 This refers to the outer diameter of the impeller front sealing ring.
7. The axial force balancing structure for a centrifugal pump according to claim 1, characterized in that: The total flow area of the balance holes shall not be less than the flow area of the third axial seal.
8. The axial force balancing structure for a centrifugal pump according to claim 1, characterized in that: The pump cover has an inner boss near the impeller balance hole. The inner boss is located outside the balance hole, and the design clearance between the inner boss and the impeller rear cover plate is greater than the axial movement of the pump impeller.